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OPERATIVE MECHANIC, 
 
 % 
 
 AND 
 
 BRITISH machinist; 
 
 BEING A 
 
 ^practical ©i^jjlag 
 
 OF THE 
 
 MANUFACTORIES AND MECHANICAL ARTS 
 
 OF THE 
 
 UNITED KINGDOM. 
 
 By JOHN NICHOLSON, Esu. 
 
 CIVIL ENGINEER. 
 
 LONDON : 
 
 PRINTED FOR KNIGHT AND LACEY, 
 
 PATERNOSTER-ROW ; 
 
 AND WESTLEY AND TYRRELL, DUBLIN. 
 
Printed by D. Sidney, and Co, 
 Northumbei land-street, Strand. 
 
 THE GETTY C£»v{TER 
 LIBRARY 
 
GEORGE BIRKBECK, Esq. M.D. 
 
 PRESTDBNT OF THE LONDON MECHANICS* INSTITUTION, 
 (§*C. 
 
 Sir, 
 
 In an age like the present, when the rich and the 
 powerful identify their interests with the welfare of the 
 poor and uninformed, when the wise and the good com- 
 bine in furthering the diffusion of sound principles and 
 useful knowledge among those who constitute the most 
 important, though hitherto the most neglected, portion of 
 the community, there is not one who can view the future 
 in the past but must anticipate with such data before 
 him, a change as brilliant in its effects, as it is honour- 
 able to those who are engaged in promoting it. 
 
 The advanced state of science, and the comprehen- 
 sive views of a just and liberal philosophy, animate 
 those who for many years have compared theory with 
 practice to come forward in the hope of being able to 
 offer something in aid of the common cause. 
 
iv 
 
 DEDICATION. 
 
 Such feelings. Sir, have encouraged me to publish the 
 following pages, which, as an earnest of their future suc- 
 cess, I am permitted to dedicate to yourself. 
 
 A Work of this kind, combining in the most condensed 
 form the acknowledged principles and recent improve- 
 ments in Mechanical Science, and professing to be 
 adapted in every possible way to the use of the Me- 
 chanic and Machinist, could not well find a Patron more 
 congenial to its Spirit than one, who, during a long 
 series of years, has laboured with no common devotion 
 in promoting their benefit. 
 
 I am, 
 
 Sir, 
 
 Your most obedient, and 
 
 much obliged humble Servant, 
 
 JOHN NICHOLSON. 
 
PREFACE. 
 
 The discoveries of Watt and Arkwright, which 
 yielded atonce such immense national as well as individual 
 prosperity, must ever be regarded as forming a new era 
 in the arts of life and the domestic policy of nations. 
 The riches, extraordinary as unprecedented, inexhaus- 
 tible as unexpected, thus acquired by a skilful system of 
 mechanical arrangement for the reduction of labour, 
 gave the impetus which has led to the numerous dis- 
 coveries, inventions, and improvements, in every de- 
 partment of our manufactures, and raised them to their 
 present state of perfection. 
 
 With respect to our primary and most elaborate pieces 
 of mechanism, however intricate and incomprehensible 
 they may appear to the inexperienced, they are in the 
 eye of the practical man mere elegant modifications and 
 combinations of a few simple principles. These princi- 
 ples, after some necessary observations on the Forces 
 acting on Matter, on Friction, and the Centre of Gravity, 
 are fully elucidated in the account of The Mechani- 
 cal Powers.” 
 
 These are followed by what is indispensably necessary 
 to the proper construction of Mill-work, viz, a descrip- 
 tion of Bevel and Spur Geer, the longitudinal connex- 
 tion of Shafts, termed Coupling, the most approved 
 
VI 
 
 PREFACE. 
 
 method of Disengaging and re-engaging machinery, 
 and of the Equalization of Motion, with some general 
 Practical Observations, given under the article “ Mill 
 Geering.” 
 
 The reader who attentively peruses these articles will 
 be in possession of the primary points of Mill* work ; 
 we have, therefore, next introduced to his notice, under 
 Animal Strength, Water, Wind, and Steam, the 
 best modes of applying the Moving Powers ; and to 
 them is annexed a short, though concise, account of 
 Brown's V acuum or Pneumatic Engine, which may, 
 with improvements, be made most effective for loco- 
 motion and other light purposes. 
 
 As the reduction of wheat into flour forms so essential 
 a part of domestic (economy, and as the force which 
 gives a rotatory motion to the upper mill-stone is almost 
 invariably imparted either by wind or water, we have 
 thought it no deviation from scientific arrangement, to 
 introduce at the end of these two articles a description 
 of a Flour-mill ; as, by that means, the reader will 
 be enabled to form a tolerably correct notion of the man- 
 ner of imparting motion from the water-wheel, or leader, 
 to the other parts of machinery. And while upon this 
 subject we have, with a view to make the Work gene- 
 rally useful, described the hand and foot methods of 
 grinding corn, that those who live not in the vicinity of a 
 mill, or who do not choose to submit to the impositions 
 said to be practised by many millers, may, at a compa- 
 ratively trifling expense, have the work performed at 
 home. 
 
 A knowledge of the strength of materials being 
 
PREFACE. 
 
 Vll 
 
 at all times important in the construction of Mill- work, 
 more particularly in those parts which have to sus- 
 tain the greatest force, or put the whole of the other parts 
 of the machinery in motion, we have, next to the Moving 
 Powers, inserted a letter from Mr. Rennie, jun. to Dr. 
 Young, describing a series of very satisfactory experi- 
 ments made on this subject. 
 
 A description of Hydraulic Engines next follows > 
 and these are succeeded by certain Simple Machines 
 acting as accessories to our manufactures. So that, by the 
 time the reader has advanced thus far, he will have be- 
 come so thoroughly intimate with machinery, as easily 
 to comprehend and appreciate the several excellencies 
 of our Staple Manufactures, which are next unfolded 
 to his view. 
 
 The whole was intended to be concluded with an ex- 
 amination of those arts termed Manual, in a Treatise 
 on the Art of Building; except, indeed, with the 
 addition of an Appendix, containing a short and concise 
 treatise on Practical Geometry and Mensuration, 
 with a Collection of approved Receipts, and a Glos- 
 sary ; but the interest which has lately been excited re- 
 specting Railways and Locomotive Engines has led 
 to the extension of the Work, about thirty pages, witli an 
 article on those constructions. 
 
 Although there are several very excellent treatises on 
 Mechanics and Mill-work now extant, yet, presuming 
 on an arrangement widely different to that of others, by 
 which the least erudite and most inexperienced may ac- 
 quire something more than a mere Superficial Knowledge 
 of Machinery, the Author trusts that the following pages 
 will meet with a favourable reception. 
 
Vlll PREFACE. 
 
 In the course of his labours he has derived mate- 
 rial assistance from many of his scientific friends, to 
 whom he thus publicly expresses his acknowledgments ; 
 and more particularly to that Gentleman to whom the 
 volume is dedicated. 
 
 In a Work of such a nature it is generally understood 
 that extracts are justified, as the description of many 
 things not new are requisite, and the language could not 
 in general be improved. In such cases, however, the 
 authority has, in general, been acknowledged, and in a 
 way calculated to advance the honour and interest of 
 every improver and discoverer. 
 
 The volume in its design and execution is offered as a 
 companion to the workshop, consequently abstract 
 and theoretical principles have been allowed to mingle 
 no further than has been indispensably necessary to the 
 perfect illustration of the use and application of the 
 object described. The Work has, therefore, no simi- 
 larity to the Mathematical Illustrations of Wood, Gre- 
 gory, or Emerson, each of which, and more particu- 
 larly that of Dr. Olinthus Gregory, deserves to be 
 spoken of with great respect. 
 
 A Book comprehensive and practical, embracing the 
 whole subject as living and contemporaneous, and as 
 connected with private profit and public glory, instruc- 
 tive to individuals and illustrative of the genius of the 
 age in its best direction, has been the object of the 
 Author, and he hopes he has not laboured in vain. 
 
 London, 
 
 March , 1825. 
 
CONTENTS. 
 
 OWERS 
 
 ON MATTER. 
 
 Of the Action of Forces 
 
 Friction .... 
 
 the Centre of Gravity. 
 
 MECHANICAL 
 
 The Lever 
 
 Wheel and Axle 
 Pulley . 
 
 Inclined Plane 
 Wedge . 
 
 Screw 
 
 Simple Combinations of the Mechanical Powers. 
 
 MILL GEERING, 
 
 Definition of Terms 
 To describe the Cycloid and Epicycloid 
 On Teeth of Wheels, Spur Geer 
 Bevel Geer 
 
 Couplings. Square couplings with double bearings 
 Clutches or Glands 
 Boring IMill-Clutchcs . 
 
 Self-easing Coupling . 
 
 Bolton and Watt's Coupling Link 
 Hook's Universal Joint 
 ' Double Universal Joint 
 Disengaging and Re-engaging Machinery 
 Sliding Pulley 
 Fast and Loose Pulley 
 Bayonet .... 
 
 I^ever 
 
 Tightening Roller 
 Friction Clutch 
 Friction Cone 
 
 Self-disengaging Coupling . 
 
 On Equalizing the IMotion of Machinery 
 Steam-Engine Governor 
 Water-Wheel Governor 
 Wind-Mill Governor 
 Tachometer, by Donkin 
 General Observations 
 
 Page. 
 
 G 
 
 15 
 
 7 
 
 10 
 
 11 
 
 T2 
 
 13 
 
 ih. 
 
 IG 
 
 20 
 
 21 
 
 23 
 
 28 
 
 30 
 
 31 
 ib. 
 ib. 
 
 32 
 ib. 
 ib. 
 
 32 
 
 33 
 ib. 
 ib. 
 31 
 ib. 
 ib. 
 
 35 
 ib. 
 ib. 
 
 36 
 
 37 
 
 38 
 
 39 
 13 
 
X 
 
 CONTENTS 
 
 ANIMAL STRENGTH. 
 
 Page. 
 
 Immediate Force of Men, without deducting fot Friction . . 52 
 
 Performance of Men by Machines 54 
 
 Force of Horses ih. 
 
 W ork of Mules 55 
 
 Extraordinary Feats of Strength . 56 
 
 How extraordinary Feats may be performed by Men of ordinary 
 
 Strength. 01 
 
 WATER. 
 
 Water-Mills 64 
 
 Undershot- Wheels 65 
 
 Smeaton’s Experiments on ib. 
 
 by Lambert 72 
 
 Overshot Wheels 75 
 
 by Burns 76 
 
 Smeaton’s Experiments on .... 79 
 by Burns, without a Shaft . . . .84 
 
 Chain of Buckets 85 
 
 Breast-Wlieels . . 87 
 
 in which the water runs over the Shuttle . . 89 
 
 Lloyd and Ostell’s ih. 
 
 with two Shuttles 90 
 
 Barker’s Mill 92 
 
 Tide-Mills 94 
 
 Wheel-race and Water-course 104 
 
 Mill-Courses 105 
 
 Water-courses and Dams 107 
 
 Penstock 109 
 
 Pentrough by Smeaton 110 
 
 Nouaille Ill 
 
 Method of laying on Water in Yorkshire 112 
 
 Sluice Governor 113 
 
 Rules for constructing Undershot Wheels, by Ferguson . . .114 
 
 Brewster . .119 
 
 Treatises on Mill-Work 120 
 
 WIND. 
 
 Vertical Windmills 122 
 
 Post Mill ^ ib. 
 
 Smock Mill ........ 123 
 
 Smeaton’s Experiments on, ..... 125 
 
CONTENTS. 
 
 Vertical Windmill. Modelling" of Sails 
 
 
 
 
 XI 
 
 Page. 
 . 128 
 
 Clothing- and unclothing- Sails while in motion 
 
 
 . 130 
 
 Baines’s Sails .... 
 
 
 . 
 
 
 . 132 
 
 Equalizing the motion of Sails 
 
 
 . 
 
 
 . 133 
 
 Avith eight quadrangular Sails 
 
 
 . 
 
 
 . 135 
 
 Horizontal Windmill 
 
 
 
 
 . 139 
 
 STEAM. 
 
 Steam-Engine 
 
 
 9 
 
 
 . 164 
 
 by Savary .... 
 
 
 
 
 . 166 
 
 Newcomen 
 
 
 
 
 . 168 
 
 Watt .... 
 
 
 
 
 . 170 
 
 Hornblowcr 
 
 
 
 
 . 182 
 
 Woolf . . . -. 
 
 
 
 
 . 191 
 
 Bell-Crank Engine 
 
 
 
 
 . 205 
 
 Vibratory Engine 
 
 
 
 
 . 206 
 
 Rotatory Engine 
 
 
 
 
 . ib. 
 
 High-Pressure Engine 
 
 
 
 
 . 207 
 
 Lean’s Reports 
 
 
 
 
 . 209 
 
 General Observations 
 
 
 
 
 . 212 
 
 Brown’s vacuum, or pnuematic engine. 
 
 
 
 
 . 216 
 
 FLOUR-MILLS. 
 
 Flour-Mills 
 
 
 
 
 . 142 
 
 Mill-Stones .... 
 
 
 
 
 . 144 
 
 FenAvick’s Tables 
 
 
 
 
 . 148 
 
 Family Mill 
 
 
 
 
 . 158 
 
 Hand-Mill 
 
 
 
 
 . 160 
 
 Foot-Mill 
 
 
 
 
 . 161 
 
 Kneading-Mill * 
 
 
 
 
 . 162 
 
 Rennie on the strength of materials 
 
 
 
 
 . 218 
 
 HYDRAULIC ENGINES. 
 
 The Tympanum . . , . 
 
 
 
 
 . 228 
 
 De la Faye’s Wheel 
 
 
 
 
 . 229 
 
 The Noria 
 
 
 
 
 . 230 
 
 The Persian Wheel 
 
 
 
 
 . lb. 
 
 Paternoster Work 
 
 
 
 
 . 231 
 
 Hiero's Fountain 
 
 
 
 
 . lb. 
 
 Darwin’s Engine ...... 
 
 
 
 
 . 232 
 
 Hungarian Machine 
 
 
 
 
 . 233 
 
 BosAvell’s improvement of ditto. 
 
 
 
 
 . 235 
 
Xii CONTENTS. 
 
 The Spiral Pump at Zurich . 
 
 
 
 
 
 Page. 
 . 237 
 
 Desagulief s Drawer and Bucket 
 
 . 
 
 
 . 
 
 
 . 242 
 
 Sarjeant’s Machine 
 
 . 
 
 
 
 
 . 213 
 
 Dearborn’s Pump-Engine 
 
 . 
 
 
 
 
 . 244 
 
 Archimedes’ Screw 
 
 . 
 
 
 
 
 . 246 
 
 Pressure Engine .... 
 
 
 
 
 
 . ib. 
 
 Treatises on Hydraulic Engines 
 
 . 
 
 
 
 
 . 249 
 
 Pumps. The Common Pump 
 
 . 
 
 
 
 
 . 250 
 
 Pump with little Friction . 
 
 . 
 
 
 
 
 . 255 
 
 Pumps. Sucking-Pump, by Taylor 
 
 . 
 
 
 
 
 . 256 
 
 Todd’s improvement of the Common Pump 
 Lifting-Pump 
 
 
 
 
 . ib. 
 
 . 257 
 
 Forcing-Pump 
 
 . 
 
 
 
 
 . 258 
 
 Ctesebes’ Pump 
 
 . . 
 
 
 
 
 . 259 
 
 Stevens’ Pump. 
 
 . 
 
 
 
 
 . ib. 
 
 Tyror’s Pump 
 
 . 
 
 
 
 
 . 261 
 
 Franklin’s Pump 
 
 . 
 
 
 
 
 . 262 
 
 Brunton’s Force Pump 
 
 . 
 
 
 • 
 
 
 . 253 
 
 Smeaton’s three Barrel ditto 
 
 . 
 
 
 
 
 . 265 
 
 Chain Pump 
 
 . 
 
 
 9 
 
 
 . 267 
 
 by Coles 
 
 . 
 
 
 
 
 . ib. 
 
 Leslie’s method of working Ship’s Pumps 
 
 
 
 
 . 269 
 
 Hand-Purnp by Martin . 
 
 . . 
 
 
 
 
 . ib. 
 
 Jekyl 
 
 . 
 
 
 
 
 . 270 
 
 Clarke’s mode of applying manual force to 
 
 pumps 
 
 
 . 273 
 
 Pump-Pistons, by Bonnard 
 
 . . 
 
 
 
 
 . 274 
 
 Belidor 
 
 . 
 
 
 
 
 . 276 
 
 Fire-Engine, byNewsham 
 
 . 
 
 
 
 
 . 277 
 
 Rowntree 
 
 . 
 
 
 
 
 . 281 
 
 SIMPLE MACHINES ACTING AS iVCCESSORS TO MANU- 
 
 FACTURES. 
 
 Jacks for Lifting Weights .... 
 
 
 
 
 
 Cranes 
 
 
 
 
 
 . 283 
 
 Presses. Cider-Press 
 
 , . 
 
 
 
 
 . 291 
 
 Screw-Press, for paper-mill 
 
 . 
 
 
 
 
 . ib. 
 
 Peek’s Press 
 
 , , 
 
 
 
 
 . 292 
 
 Bramah’s Hydrostatic Press 
 
 » • 
 
 
 
 
 . ib. 
 
 Bank-note Press 
 
 , , 
 
 
 
 
 . 305 
 
 Printing-press, by Earl Stanhope 
 
 
 
 
 . 294/ 
 
 De Haine 
 
 
 
 
 
 . 298 
 
CONTENTS 
 
 xiii 
 
 Page. 
 
 Presses. Printing press by Ruthven * . . . . 298 
 
 Bacon and Donkin .... 301 
 
 Pile-Engines, by Vauloue 309 
 
 Bunce 310 
 
 Boring Machine 311 
 
 File Cutting Machine 314 
 
 Ramsden’s Dividing Machine 315 
 
 Lathes and Turning Apparatus by Maudesley .... 323 
 
 Smart 263 
 
 MANUFACTURE OF METALS. 
 
 Iron 328 
 
 Steel 340 
 
 Wire ........... 344 
 
 Lead 356 
 
 MANUFACTURE OF FIBROUS MATERIALS. 
 
 Paper 365 
 
 Cotton 378 
 
 Wool 388 
 
 Silk 392 
 
 Flax 400 
 
 Weaving 410 
 
 Hemp and Rope - 4ig 
 
 SUNDRY MANUFACTURES. 
 
 Saw-Mills - 441 
 
 Bark-Mill - 445 
 
 Oil-Mill 447 
 
 Colour-Mill - 454 
 
 Indigo-Mill - 455 
 
 Pottery - -- -- 456 
 
 HOROLOGY. 
 
 Clocks - 486 
 
 with three Wheels and two Pinions, by Dr. Franklin - - 490 
 
 J. Ferguson - - ib. 
 
 for exhibiting the apparent daily motions of the Sun and 
 
 Moon, and state of the Tides, &c. - - - - 492 
 
 Striking part of an eight day Clock - - - . _ 496 
 
 description of curious Clocks 497 
 
 Watch 500 
 
 Table of Trains - . 504 
 
XIV 
 
 CONTENTS. 
 
 Pa 2 ;e. 
 
 Chronometer - 507 
 
 Escapements - *. - - 515 
 
 Recoiling-, or Crown-wheel 510 
 
 by (himining - - - - - - - -517 
 
 for Watch - -- -- -- - 518 
 
 by Prior - -- -- -- - 519 
 
 by Reid - - - - - - - - 520 
 
 by De la Foils ------- 523 
 
 Pendulums - 524< 
 
 Mercurial, by Graliam ------ 525 
 
 Gridiron, by Harrison ------ 523 
 
 Lever, by Ellicott - - - - - - - ib. 
 
 Tubular, by Troughton ------ 527 
 
 by Reid --------- 27/. 
 
 by Ward - -- -- -- -- 528 
 
 Sympathy of the Pendulums of Clocks. - ib. 
 
 RUILDING. 
 
 Prefatory Observations - -- -- -- - 529 
 
 IMortar - -- -- -- -- 530 
 
 Brick-making - -- -- -- - 532 
 
 Masonry - -- -- -- -- -- 536 
 
 Bricklaying - -- -- -- -- - 547 
 
 Carpentry - -- -- -- -- - 5 qq 
 
 Joinery - -- -- -- -- -- 581 
 
 Plastering - C 03 
 
 Slating 621 
 
 Plumbing - 628 
 
 Painting - -- -- -- -- - 639 
 
 Glazing - -- -- -- -- -- 635 
 
 Rail-Roads and Locomotive Engines. ------ 643 
 
 APPENDIX. 
 
 Geometry - -- -- -- -- - 673 
 
 Mensuration - -- -- -- -- - 688 
 
 Useful Receipts - 707 
 
 Glossary - -- -- -- -- - 772 
 
( XV ) 
 
 DESCRIPTION OF THE FRONTISPIECE. 
 
 
 This Plate represents a front view of a Steam-Engine con- 
 nected with a Sugar-Mill, as constructed by Messrs. Taylor 
 and Martineau, who liave kindly permitted our draftsman 
 to make a drawing of it. 
 
 This Engine, being only twelve times larger than the 
 drawing, is, from its compactness and simplicity of con- 
 struction, peculiarly applicable to most of the manufactures 
 round the metropolis, where power of a moderate amount 
 is in general required. 
 
 It works horizontally, at from 30 to 401bs. pressure per 
 square inch, without condenser, having metallic pistons 
 and slide-valves, and only requires eight screw-bolts to 
 fasten it to oak sleepers, or frame-work of moderate scant- 
 ling. 
 
 A is a crank connected with the piston-rod, which, as it works in the 
 cylinder horizontally, cannot be seen. B is the cylinder, into which 
 steam is admitted from the boiler, by means of the pipe C C C. The 
 amount of steam flowing- into the cylinder is regulated by the throttle 
 valve at D, which is opened and shut at proper intervals by the rod E E 
 E. F F is the governor, or regulator, consisting of two heavy balls, 
 with the sliding collar a, suspended from the top of a vertical spindle d b. 
 at the axis c. This spindle is connected with the main shaft, by a strap 
 passing over the sheeves or pullies, G G G, which cause it to revolve ; and 
 as its speed varies with that of the main shaft, the governors F F, ac- 
 cording as its speed increases or decreases, have a tendency either to fly 
 from, or approach to, the spindle. This rise or depression of the go- 
 vernor affects the rod E E E, to which it is connected, and regulates the 
 quantity of steam flowing from the boiler into the cylinder. 
 
 H is a piece to connect the top part of the piston-rod with the rod I, 
 so that by the motion of the crank the rod I is also moved, which rod 
 moves the slide valves in the cylinder K. By the action of these valves, 
 steam is alternately admitted on the opposite sides of the piston ; and as 
 the engine does not condense its steam, there are two pipes, placed 
 one at each end of the cylinder, to carry it off. One of these pipes is 
 seen at N. When the piston has been driven by the force of the 
 steam to the other extremity of the cylinder, the steam, by the action of 
 the slide valves, is shut off from this end, and allowed to flow into the 
 
( XVI ) 
 
 opposite end of the cylinder ; the orifice of the pipe N being- at the same 
 time opened, the steam at this end is, by the returning- action of tlic 
 piston, driven through the pipe N, and conveyed away under ground, 
 leaving this end of the cylinder ready for a fresh supply. 
 
 The power generated by this simple arrangement is made to effect the 
 required purpose by means of the shafting 0 0 0. On this shafting, at 
 a little distance from the engine, is an eccentric, L, to raise the rod ]M, 
 to pump water into the boiler when required : and at nearly the further 
 end of the shafting is another eccentric, W, which imparts motion to the 
 rod V, for the purpose which we shall hereafter describe. 
 
 The rotatory motion which the crank has received from the engine is 
 imparted to the shafting, to the eccentric L, the coupling-box d, the 
 fly-wheel P, the eccentric W, and the pinion Q, which plays in the large 
 cog-wheel, R, on the shaft S, and thence is imparted to the rollers of a 
 sugar-mill, which rollers are moved at equal speeds by the pinions U U. 
 
 In this, and most other Sugar-mills, there are three rollers, 
 two at the bottom, and one lying between the other two at 
 the top. Through these rollers sugar canes are passed, and 
 the compressed juice falls into a receiver, from whence it 
 is pumped, by the movement of the rod V, into a copper, or 
 other receiver. At that part of the shafting marked e c, 
 sufficient space is left to allow of play when the canes are 
 passed through the rollers, otherwise the shafting would 
 be very apt to snap and be destroyed. 
 
THii 
 
 OPERATIVE 
 
 MECHANIC AND MACHINIST. 
 
 OF THE ACTION OF FORCES. 
 
 Aiu i. 
 
 which, if acting upon i q y> newly created force 
 
 maiiitain.it in a state of rest. ,neh an 
 
 act upon a body . g ^nder’ whose action that 
 
 extent, as to overcome the ^tte exists, the result 
 
 body, in common with all ^“r m 
 
 will be motion created force exceeded the 
 
 exact Pijortmn ' previously acting upon it in the 
 amount ot forces ^ ^ ^ pound 
 
 opposite^direction. „r,mnd, the amount of motion 
 
 weight three feet fiom |>ouno, 
 
 created by that action * thJ force of gravity or weight 
 ,ewly ciTated 
 
 which acted on the ma^ ; . motion could not 
 
 the force of gravity, ^ f gravity had not existed, 
 
 have been created; and If the ,,ould be 
 
 it is again manifest tha ynt of the whole of the force 
 
 exactly m F°P“vtion exactly equalled, 
 
 he had applied. Again, it 1 ' . .ion motion could not 
 
 and did not exceed the force of at rest. 
 
 '‘7hL .nt?”’re>.. n»tot.iil«4 b, the c«»ir»y,»=tlon •( 
 
 the f<^vm equilibiimn - h gravitation, main- 
 
 or more '’“^les are by the rest: thus, if a bar of 
 
 tamed in a state of q ? centre C, it will balance, 
 
 iron, A B, tig. 1, J “u^tity of matter in C A is 
 
 “ T'^'laUo thafin C B and the amount of the gravitating 
 exactly that in ^^^tter that is in each 
 
 force proportional to tl q J ^ ^ 
 
 equilibrious. ^ 
 
 / 
 
2 
 
 THE OPERATIVE MECHANIC 
 
 In the common operations of mechanics, the former 
 state of equilibrium frequently occurs ; the latter rarely, 
 and never with any permanent duration; by the term 
 equilibrium, therefore, in general, is understood, the position 
 first cited. 
 
 Upon duly considering that matter, when between forces 
 acting in opposite directions, is in a state of equilibrious 
 quiescence, it will be manifest, that motion cannot be 
 obtained without destroying the equilibrium. It must 
 not therefore be supposed, that the forces of gravitation 
 or adhesive attraction can produce motion, as has been 
 erroneously urged by some, but rather that all the mo- 
 tion these powers are capable of producing was primarily 
 exerted to bring matter into that state of equilibrium in 
 which we find it. Wherever that equilibrium is disturbed 
 by extraneous causes, the resultant motion, attainable by 
 such disturbance of the general equilibrium, has long since 
 been known, and applied to useful purposes. We may with 
 propriety, therefore, deduce from these considerations, the 
 perfect fallacy of that most ruinous and speculative notion of 
 a perpetually moving force. Many who have wasted their 
 time in attempts to attain that object, have either supposed 
 that the force of gravitation could obtain motion, or that 
 motion once obtained could of itself increase its force ; which 
 was about as rational as to suppose that any substance could 
 of itself increase its own bulk. The powers with which 
 nature has supplied us, have, as far as we are aware of, 
 been already applied ; and should there be others existing of 
 which we are ignorant, or which we have not reduced to our 
 command, the search for, and developement of such objects, 
 are praiseworthy and valuable: but let us with confidence 
 hope, that the labours of ingenuity will no longer be drawn 
 aside from the paths of prolific study, by this destructive 
 phantasy. 
 
 Returning from this digression, when a body is operated 
 upon by a force, and acquires motion, that motion, taking 
 into account the amount of space through which the body 
 passes in a given time, is called the velocity of the body ; 
 and according as the extent of distance increases or decreases 
 in a greater or less period of time, the velocity is said to 
 increase or decrease. 
 
 If a force acting upon any body, and causing motion, 
 shall continue to act upon it in the same direction, so as 
 to continue to increase that motion, the body, under such 
 circumstances, is said to attain accelerated velocity. And 
 
MiEC’^[iA:^]i'r A'L 'P o\yy.'K]KS 
 
 PL.l. 
 
 From 1 to L7. 
 
 y<Yir ^ '*Vnm<f 
 
AND MACHINIST. 
 
 3 
 
 if a body be put in motion by a certain force, and another 
 force operate upon it in a contrary direction, so as to tend 
 to bring it to a state of equilibrium^ such motion is called 
 retarded motion.* 
 
 * The simplest example of accelerated motion, is exhibited in the 
 action of the force of gravitation upon a falling body, where the force 
 continues to act during its descent, and regularly increases in velocity ; 
 so that if a body A, fig. 3, be allowed to fall from that position towards 
 the earth, it will pass through sixteen feet during the first second of 
 time, forty-eight feet during the next, and eighty feet during the third. 
 Had its motion been regular during these three seconds of time, it would 
 have passed through only three times sixteen, or forty-eight feet, whereas 
 it has passed through one hundred and forty-four feet, by reason of the 
 force which first caused its motion continuing to act upon it. Now as 
 its velocity increases regularly, we may conclude, that during the per- 
 formance of the first half of the sixteen feet, it was not proceeding at the 
 rate of sixteen feet per second; and if we suppose it was proceeding 
 only at half that velocity, then it must have travelled through the second 
 half at the rate of thirty-two feet per second ; or, if the first eight feet 
 took three quarters of the second, the second eight feet must have been 
 performed in the remaining quarter, therefore, when the body arrived at 
 B, it would be proceeding at the rate of thirty-two feet per second ; to which, 
 if we add the force that continues to urge it at the rate of sixteen 
 feet per second, it will exhibit, for the second space, a velocity of forty- 
 eight feet per second ; and if for the third space we double its increasing 
 velocity of thirty-two feet, and add that created by the continued force, 
 we shall have twice thirty-two, and sixteen, are eighty, which is the 
 result of experiment. . The velocity of bodies under the continuous action 
 of any given force, will, it appears, increase as the odd numbers 1, 3, 5, 
 7, 9, &c., that is, sixteen feet during the first second, thrice sixteen feet 
 during the next second, five times sixteen during the third second, and 
 so on; or, as the relative portions of the superficial space under equal 
 parts of the perpendicular in a right angled triangle, as represented 
 at fig. 3 : where 0 to 1 represents the first second of time, 1 to 2 the second, 
 and 2 to 3 the third. It will be perceived, that under each of these por- 
 tions, the space contained in the triangle will be as 1, 3, 5 ; such is uniform 
 accelerated motion. But if the continuous force, which has been shown 
 to increase the velocity, vary in its action upon the body, it is plain the 
 increase will be no longer uniform. 
 
 From a clear comprehension of the acceleration of motion in bodies 
 the retardation of motion will be easily conceived: for example, if a 
 body be cast perpendicularly from the earth, as in the firing of a shot 
 from a cannon upwards, the force of the powder, overcoming the force 
 of gravitation, will cause the ball to rise with a certain velocity, whilst 
 that attraction continuing to operate in the opposite direction, checks 
 by regular gradations the created force, and eventually destroys it. 
 Tlius the distance which the shot would have accomplished during the 
 first second of time, is reduced by sixteen feet; that which it would 
 have accomplished during the next second, by forty-eight; and so on 
 until the created power is counterbalanced by the force of gravity, and 
 the ball arrives at a state of rest ; when the force of gravity acting upon 
 it solely, will cause it to move in the opposite direction, till it descends to the 
 earth 
 
4 
 
 THE OPERATIVE MECHANIC 
 
 When a ball^ attached to a centre by a flexible cord^ is put 
 in motion by any one force, which, in common with all other 
 forces, acts in a right line, the motion will be circular. The 
 tendency which such body has to fly from the centre, is 
 called the centrifugal force j and that exerted by the cord to 
 draw it towards the centre, the centripetal force. 
 
 When a body is set in motion by any force, it is enabled, 
 to a certain extent, to act on other bodies, and create 
 motion in them ; and, as the velocity it obtained was as 
 the power expended to create that motion, so is the power 
 of transmitting that motion to its velocity. This power 
 of communicating motion, or, in other w^ords, this force 
 possessed by matter in motion, is termed momentum, or 
 the moving force; and the mode of transmitting it, impact: 
 as this force is proportional to the velocity possessed by 
 every particle of matter composing any body, the mo- 
 mentum must be represented by the quantity of matter 
 multiplied by its velocity. For instance, suppose one hun- 
 dred particles of matter were moving at the rate of one foot 
 per second, the power requisite to overcome their force 
 is exactly the same as that which would be necessary to arrest 
 the motion of one particle moving at the rate of one hundred 
 feet per second : for the velocity of the hundred particles 
 being one foot per second each, their total force would be 
 the force existing in one of them multiplied by one hundred : 
 and again, as the force is in proportion to the velocity, one 
 particle moving at the rate of one foot per second, multipled 
 by one hundred in regard to velocity, will produce a similar 
 result. Also, if a body of one pound weight be moving at 
 the rate of one foot per second, it will possess a certain 
 momentum, and if either its weight or its velocity be doubled, 
 its momentum will be likewise doubled ; if both be doubled, 
 the momentum will be quadrupled. 
 
 Having now considered the action of one and two forces 
 acting together in opposite and similar directions, we will 
 proceed to examine the action of two forces upon a body, 
 acting neither in the same, nor in contrary directions. Thus, 
 if the line A B, fig. 4, represent a force sufficient to carry 
 the body A to the point B, and A C represent another 
 force sufficient to carry the body A to the point C, then 
 AC and A B being equal to CD and B D, and those two 
 forces act upon the body subsequently to each other, Ave 
 may conceive that the body would, by passing over the 
 lines A B and B D, or iV C and C D, be carried to the point 
 D. Now, if they act upon the body at the same instant, 
 
AND MACHINIST. 
 
 5 
 
 the result will be the same, and the total expenditure of the 
 forces will place the body, passing by the line A D, at the 
 point D. Likewise, if the forces A B and A C be not at right 
 angles, as in fig. 5, still as C D and B D are equal, and in 
 similar directions to A B and A C, the motion received from 
 them by A will be represented in amount and direction by 
 the line AD. But supposing AB shall be twice or thrice 
 the power of A C, then the effect will be the same as is shown 
 in fig. 6, \vhere the line AB represents thrice the power of 
 A C. The separate actions of A B and A C wall be repre- 
 sented as before by B D and C D, which would place the 
 body A at the point D ; therefore their combined force will 
 cause it to pass by the diagonal line AD, as in the former 
 instance. This pioves that any number of forces acting 
 upon a body in however many lines, not directly opposite 
 to each other, will be compounded into one force : for suppose 
 three forces, A B, AC, and A F, fig. 7? to operate in their 
 several directions at the same instant, on the body A, they 
 will be compounded into the force represented by A I ; for if 
 w'e describe a parallelogram as before by the lines A B and 
 A C, those two forces will be compounded into a force repre- 
 sented by A D ; and again, if we do the same with the t^vo 
 forces A C and A F, we shall have the force A H composed of 
 them. We have therefore two forces A D and A H com- 
 pounded of the three original forces. If we proceed with 
 these two in the same manner, they will be compounded into 
 the force represented by Al; DI and HI completing the 
 parallelogram of which A I is the diagonal : so that any num- 
 ber of forces acting in any number of directions, excepting 
 in opposite ones, may be compounded into one, wLich is 
 termed their composant, and which is always represented by 
 the diagonal of a parallelogram, like that already shown. 
 
 The resolution of forces is exhibited by reversing this 
 problem ; for as any number of forces may be combined 
 into one force, so may one force be resolved into any 
 number. If a single force be represented by a ball mov- 
 ing with a certain velocity in the direction of the line A B, 
 fig. 8, when it shall come in contact with and act upon the balls 
 C and D, these two balls will each of them move with one 
 half of the velocity with which B was impelled, and in the 
 direction of the lines C H and D I, drawn from the centre of B 
 through each of their centres : so that if the force of B be 
 divided into two equal portions, each of those portions 
 may, by a similar process, be again divided, resolving the 
 original force to infinity. 
 
6 
 
 THE OPERATIVE MECHANIC 
 
 The next effect of forces upon bodies producing motion, 
 is that in which a body receives motion from one force, 
 whilst it is under the continuous action of another force, not 
 acting upon it in an opposite direction. Suppose the ball A, 
 fig. 9, to be ejected from the mouth of a cannon, the in- 
 stant it has left it at A, it will be under the influence of the 
 force of gravitation, which will cause it to descend towards 
 the earth in the manner already shown when speaking of 
 accelerated motion, and ultimately will bring it to a state of 
 rest at the point B : for supposing that the ball, by the 
 force of the powder, leaves A, and travels in the first second 
 of time a given number of feet, expressed by the line A C, 
 the gravitating force during such action will cause it to 
 descend sixteen feet, expressed by the line C D ; and during 
 the next second, supposing the powder to have impelled it 
 the distance expressed by the line D E, the gravitating force 
 will cause it to fall forty-eight feet, as is shown by E F ; and 
 during the next portion of its horizontal motion, expressed 
 by F G, its descent by gravitation will amount to eighty 
 feet, represented by G B. The line, therefore, in which 
 the body would move when acted upon by these two forces 
 only, would be that of a parabolic curve ; but as the re- 
 sistance of the air is to be taken into account in all practical 
 cases, the line of motion changes very considerably, and assumes 
 one that involves a problem of exceeding complexity ; which, 
 together with many other results of the effects of combined 
 forces, is of such intricacy as to demand much more room for 
 their solution than the limits of this work will permit us to give. 
 
 OF FRICTION. 
 
 The surfaces of bodies, however smooth they may ap- 
 pear to be, will be found, upon a minute inspection, to possess 
 certain irregularities : so that if the body A B, fig. 10, have 
 to move upon the surface of the body CD, and the lower 
 surface of A B possesses prominences which enter into 
 cavities in C D, it is manifest that A B cannot be moved 
 along unless it either rises and falls the height of the several 
 prominences, or breaks them off : in the first, it will have 
 to overcome the attraction of gravitation ; in the second, the 
 attraction of cohesion. Again, if the body A B, fig. 11, be 
 placed between C D and E F, which arc pressed against its 
 sides by any applied force, and their surfaces be similar to 
 those in the former instance, to effect the movement of A B, 
 the attraction of cohesion must be overcome, as before 
 shown, or the applied force must be conquered. Such is the 
 
AND MACHINIST. 
 
 7 
 
 almost universal nature of that resistance called friction ; for 
 although the irregularities upon the surfaces of bodies are by 
 no means so manifest as those here represented, still, upon 
 minute examination, we are enabled to discover that the 
 smoothest surfaces contain them ; and as the amount of resist-- 
 ance increases in direct proportion as the irregularities present 
 themselves, we are warranted in concluding that all resistance 
 arising from friction owes its origin solely to this cause. 
 
 OP THB MECHANICAL POWERS. 
 
 The mechanical powers are six in number, the lever, 
 the wheel and axle, the pulley, the inclined plane, the 
 WEDGE, and the screw. A perfect knowledge and thorough 
 appreciation of which should be clearly understood by those 
 who purpose to examine into the effects of mechanical com- 
 binations ; the whole of which, however intricate, originate 
 from, and are reducible to, one or more of the laws which 
 govern these simple machines. 
 
 In demonstrating the mechanical powers, that which is not 
 strictly true must be admitted : the force of gravitation, the 
 retardation of friction, the resistance of the atmosphere, 
 and the irregularity arising from the partial elasticity of the 
 substances of which they are formed, must be excluded, and 
 supposed not to exist. 
 
 The first-mentioned power is the lever ^ which is divided 
 into three classes. In fig. 12, A B is a lever, and C the 
 fulcrum, or immovable point on which it rests : now, if 
 a force be applied at B, and the resistance, or the force or 
 weight to be overcome, is at A, then, with the fulcrum so 
 situate between the forces, it is called a lever of the first 
 class ; and the operation of the force at B to overcome the 
 resistance at A, will be in proportion as the distance A C is 
 to the distance B C ; that is to say, if B C be four times the 
 distance of A C, the force applied at B will be exactly equal 
 to four times the same amount of force at A ; or one pound 
 weight at B will counterbalance four pounds weight at A ; 
 but to whatever height (suppose one foot) the weight at A 
 be raised, B must descend four times that space, and con- 
 sequently, to place B in its original position, the force applied 
 must be equal to the raising of four single pounds one foot 
 each, which is the same as the raising of four pounds one 
 foot, as was effected at A. 
 
 An actual gain of power does not exist, but the gain in 
 convenience is great; for, by the operation of one pound, 
 four pounds is moved, which, but for the invention of the 
 
8 
 
 THE OPERATIVE MECHANIC 
 
 lever, could not have been effected. A man whose utmost 
 strength could lift no more than one hundred and fifty- 
 pounds is by this means rendered capable of giving motion 
 to four times that weight, although he is obliged to exert his 
 strength through four times the distance. A lever of the 
 second class may be represented by supposing A to be the 
 fulcrum, B the force applied, and C the weight, or resistance 
 to be overcome. The effect of this lever must be estimated 
 by comparing the distances C B to A B ; the power will in- 
 crease or diminish exactly in proportion as A B exceeds C B, 
 and the distance that B moves through will increase exactly 
 in the same proportion. 
 
 Suppose, in reference to the same figure, C to be the force 
 applied, A the fulcrum, and B the resistance, it will then 
 represent a lever of the third class. The effect of levers 
 of this class is to lose power for the purpose of gaining either 
 motion or distance. For if, in the last mode, the power ap- 
 plied at B increased as the length of A B became greater 
 than C B, it is plain that in the present case, the resistance 
 at B is placed in a position to gain by the same law : there- 
 fore, the nearer the force is placed to B the greater will be 
 the effect ; and when applied at B, the greatest ; but when 
 the force is at B, it is applied direct to the resistance, and 
 the lever is abandoned; consequently C, in every position 
 between A and B, loses power to a greater or less extent. 
 As the movement of C, in the last case, was one lialf that 
 of B, so in the present case will the movement of B be twice 
 that of C. 
 
 In particular operations, levers of each of these classes 
 have their particular uses. The simplest application of the 
 first sort may be seen in scissors, shears, forceps, &c. the 
 pin in the joint is the fulcrum, the hand is the force applied, 
 and the substance to be cut or pinched is the resistance to 
 l)e overcome ; the second sort of lever is presented to us in 
 the cutting knives used by last-makers, where the hand is 
 the power, the ring into which the other end of the knife 
 is hooked is the fulcrum, and the object to be cut is the 
 resistance. Common fire-tongs are levers of the third class, 
 as they possess a capability of being extended at the ex- 
 tremities : in using them the motion of the hand produces, 
 perhaps, six times its own motion in the extremities, and a 
 loss of power exists in a similar proportion ; but as they 
 have to be used only for a short period, the loss of power 
 is of less importance than the convenience gained. This 
 last class of lever is frequently introduced in machinery, 
 
AND MACHINIST. 
 
 9 
 
 for the purpose of obtaining a rapid motion ; and as the same 
 ‘ object has been aimed at in the construction of almost all 
 animals^ we find that nature has introduced it most fre- 
 quently. 
 
 We have considered the operations of the lever by the 
 different dispositions of the acting and resisting forces and 
 the fulcrum, under the supposition that the lines of the 
 direction of the forces were at right angles to the arms on 
 which they operated, or formed tangents to the arcs which 
 the movements of those arms described ; but if we alter the 
 form of a lever from that of a right line, and the two forces 
 still maintain their parallel direction, the action on their 
 respective arms will be no longer at right angles, and their 
 effects will in consequence be varied ; the mode of estimating 
 those effects must be also changed. Fig. 13, ABC repre- 
 sents a bent lever resting upon its fulcrum B, and having 
 appended to each of its arms the weights D and E, which 
 are equal to each other and in equilibrium, notwithstanding 
 the arm B A is longer than the arm B C. Draw the hori- 
 zontal line G H, passing through the fulcrum B, then the 
 weights D and E acting in perpendicular lines, we may 
 imagine that D is suspended at the point 1, andE at the point 
 K, at which points they will operate similarly. Suppose K I 
 to be the lever, the arms I B and B K will then be equal, 
 and if their distances are multiplied into E and D, which 
 are equal forces, their effects will be equal. The action of 
 parallel forces upon levers, that do not receive the action at 
 right angles to their respective arms, should be estimated 
 by the force multiplied into a line drawn from the fulcrum, 
 perpendicular to the line of direction of each respective force ; 
 and vyhatever may be the form of the lever, it is apparent, 
 that, if the lines of direction vary from being tangents to 
 tne arcs described by its arms, their effects must be esti- 
 mated by the length of perpendiculars let fall upon the lines 
 of direction in a similar maimer. Recurring to fig. 13, it 
 will be seen, that if the arm B A rise to the position B L, the 
 perpendicular B I, if allowed to fall upon the line of direc- 
 tion, will be increased from B I to B M, and that the effect 
 of the force D over E will be augmented. This peculiarity 
 is brought into operation in a balance that has a graduated 
 scale on an arc, as A G, the divisions of which arc decreases 
 as it rises in such a manner as to exhibit, by the movement 
 of A, equal portions of force acting upon E. There is how- 
 ever a case of common occurrence, namely, that of drawing a 
 nail with the fang of a hammer, wherein the effects of the 
 
10 
 
 THE OPERATIVE MECHANIC 
 
 applied and resisting forces, being the hand and the nail, 
 although acting with a lever bent at right angles, still ope- 
 rate as though the lever were straight ; for the direction of 
 the forces being changed to the exact amount of the same 
 angle as that to which the lever is bent, they continue to act 
 at right angles to their respective arms, which arms will con- 
 sequently represent perpendiculars let fall from the fulcrum 
 on their respective lines of direction. 
 
 The principle of the bent lever is not unfrequently intro- 
 duced into machinery in order to gain a greater degree of 
 power. Suppose ABC, fig. 14, to represent a bent lever 
 moving on its fulcrum B, the operating force at A acting in 
 the direction of A D, and the resistance at C in the direc- 
 tion C E : now, as the line of direction of the force C falls 
 upon the fulcrum, it is evident, that no perpendicular can be 
 let fall from the fulcrum upon it, and consequently, the power 
 of C can be nothing in comparision to that of A, whose 
 perpendicular upon its line of direction is BA; for the in^ 
 stant the lever begins to move, suppose to A 1, C 1, then the 
 perpendicular on the line of direction of the force C, as- 
 sumes a mensurable form, as B, B 1, whilst the power of A 
 has only decreased from BA to B F. From this it will be 
 seen that at the commencement of the action of A, its 
 power over C was indefinite, but instantly after the corn- 
 mencenient of that action by the movement of C out of the 
 perpendicular E B, resistance likewise commenced, as the 
 perpendicular from the fulcrum then assumed a mensurable 
 amount. 
 
 THE WHEEL AND AXLE. 
 
 The next simple machine classed as a mechanical power, 
 is termed the wheel and axle, and is represented at fig. 15. 
 A the wheel, B a circular bar called the axle, both turning 
 upon one centre, at C. In general, the force is applied by 
 fixing a rope to the outer rim of the wheel, as represented 
 by D, whilst the resistance, or the weight, or force to be 
 overcome, is represented by E, attached by a rope to the 
 axle. By a simple analysis, this machine will be found to 
 be merely a method of obtaining a continual action of 
 levers of the first class ; for if we suppose the radius of the 
 wheel to be the longer arm of the lever, the radius of the 
 axle the shorter arm, and the centre on which they turn the 
 fulcrum, v/e have a lever of the first class ; but from these 
 two members being circular, their radii are an indefinite 
 number of levers, and, by the revolving of the wheel, a 
 
AND MACHINIST. 
 
 11 
 
 number of levers of this class are continually brought into 
 operation. The effective power of the wheel and axle must 
 therefore be calculated by the same mode as a lever of the 
 first class ; for as the radius of the wheel exceeds that of 
 the axle, so increases the power, and so increases the distance 
 that the operative force has to pass through. 
 
 The wheel and axle is applied in the apparatus for raising 
 water from wells, and is introduced in many machines, which 
 shall be shown as we proceed. 
 
 THE PULLEY. 
 
 The pulley, represented at fig. 16, is the third mechanic 
 power. It is of a circular form, fixed upon a pin that runs 
 through its centre at C, and round which it revolves. The 
 mode of applying the pulley is by placing a rope over its 
 outer rim, to the extremities of which, at A and B, the force 
 to be applied, and the weight or resistance to be overcome, 
 are indiscriminately attached, the centre C being supported 
 by the strap D. The operations of this instrument are re- 
 ferable also to the action of a lever of the first class ; the 
 pin on which it revolves is the fulcrum, and the radii of the 
 circle E F the two arms, which, being equal, no augmenta- 
 tion or diminution of power can arise. 
 
 When used in this manner, the pulley is but a method 
 of aHering the direction of the applied force. But if in- 
 verted, as shown in fig. 17, where the end of the line A is 
 attached to a fixed point, the weight or resistance being 
 at C, and the applied force acting upwards, the line from 
 A being permanently fixed, it will become a fulcrum ; and 
 the horizontal radii of the circle assume the position of 
 that of a lever of the second class ; which gains in power as 
 the respective forces of application and resistance are distant 
 from the fulcrum ; as B, for instance, is twice as far from 
 A as C, the weight or force applied at B will raise twice its 
 weight at C. 
 
 The combined action of several pullies is called a tackle, 
 see fig. 18, where A and B are two pullies fixed in the position 
 represented, and C D two others, capable of being either 
 raised or lowered ; the rope E passes over A, under over 
 B, and under C, and is permanently fixed at F. It is there- 
 fore apparent that if the weight G be suspended from the 
 centres of C and D, (both of which are in the position de- 
 scribed at fig. 17 ,) that each of them will divide its force by 
 two, and that one quarter of the weight G, placed at E, 
 
12 
 
 THE OPERATIVE MECHANIC 
 
 will counterbalance G. The pullies A and B being used only 
 to change the direction of the action. 
 
 The construction of tackles, consisting of four pullies, or, 
 as they are sometimes called, sheeves, is very similar to that 
 represented by fig. 19. 
 
 For a rule to estimate the force which is necessary to 
 overcome any force acting at G, take half the force at G 
 and divide it by the number of lower pullies in the tackle, 
 and it will give the amount necessary to counterbalance it 
 at E. 
 
 THE INCLINED PLANE. 
 
 The inclined plane is the fourth mechanical power. It is 
 represented at fig. 20, where A B is supposed to be a plain 
 surface, supported at one end, so that it may lay obliquely 
 to the horizon. By this power a heavy weight can be raised 
 with much less force than would be required to elevate it 
 perpendicularly. The manner of using it for the raising of 
 weights, is, to cause the applied force to act in a direction 
 parallel to the plane AB, and in the direction from A to 
 B, as represented by the line A E acting on the body E ; 
 the power gained is in proportion to the length of the line 
 A C, which is the base, compared to the perpendicular C B : 
 now if A C be twenty feet, and C B five, then A C being 
 four times C B, the power gained will be as four to one, 
 that is, the force equal to the raising of one pound perpen- 
 dicularly, will raise four pounds along the inclined pla,ne A B, 
 which being four times the length of C B, the force will have 
 to move through four times the distance, asAvas shown to 
 be the case in the use of the lever. This mechanical con- 
 struction, then, offers but another mode of effecting, by the 
 application of a small force for a longer period of time, that 
 which would otherwise require a much more considerable 
 force to accomplish it. The power gained in an inclined 
 plane may be always estimated by dividing the length of 
 the base of the plane by the perpendicular height of its most 
 elevated end. The application of the simple inclined plane, 
 in mechanical combinations, is not very frequ^ent in respect 
 to its power ; but its introduction is by no means uncom- 
 mon for the purpose of obtaining a. regularly ascending motion. 
 The gradual ascent of roads and railways to gain the summits 
 of hills, and the slide-ladder used by brewers in loading and 
 unloading their carts, are well known applications of it§ 
 principle. 
 
(T!FLA.^Jl(r AIL iP ©WiE jRS 
 
 I’L^. 
 
 L.^<9 
 
 J'iff. If* 
 
 From 18 to JJ. 
 
 fi‘ Sh\'klt^ Str'anJ 
 

and machinist 
 
 x3 
 
 THD wedcp:. 
 
 The fifth mechanical power is the wedge; one form of 
 which is shown at fig. 21. It operates in a' similar manner 
 to the inclined |)lane ; but instead of the resistance or force 
 to be overcome being moved along its surface^ the plane 
 itself, which is now called the wedge, is forced beneath the 
 object to be raised. Thus, if the wedge AB move upon a 
 level plane to the position A 1, the weight D will be raised 
 from its position to the height D 1 ; and, consequently, 
 will pass over the whole upper plane of the wedge A B, and 
 ultimately attain the perpendicular height B C. If A B be 
 divided by B C, the quotient, as in the inclined plane, will 
 represent the power which the wedge is capable of exerting ; 
 or if A B is four times B C, the power forcing forward the 
 wedge to A 1 is capable of raising the body D four times 
 its own amount to the position D 1. The wedge represented 
 in fig. 22, is most generally applied to the purpose of di- 
 viding wood, where the resisting force to be overcome acts 
 on both sides of it. To estimate the amount of power gained 
 by this form of the instrument, we must consider it as two 
 inclined planes, ABC and C B D conjoined ; and as the 
 forces operating at E and F are equal, we shall have, as A C 
 is to C B, so is the resistance F to the force necessary to 
 overcome it ; and as the force E and the other portion of the 
 wedge are similarly opposed, the total AD is to C B, as 
 the total resistance F and E is to the power necessary to be 
 exerted to counterbalance that resistance ; or, as many times 
 as AD will go into C B, so many times may the resistance 
 contain the amount of the applied force. 
 
 THE SCREW. 
 
 The screw is the sixth and last of the mechanical 
 powders. In the manner of its construction it is in general 
 said to bear reference to an inclined plane wound about a 
 cylinder ; but as the -power of the inclined plane corres- 
 ponds with that of the wedge, and the mode of applying 
 the facilities they possess, alone forms their difference, and 
 as the screw is almost universally moved to effect the same 
 purposes as the wedge, it w^ould, with greater propriety, 
 as regards its action, bear reference to that instrument. 
 
 Fig. 23 represents a cylinder E E, upon which w^e will 
 suppose the wedge-shaped piece, ABC, is capable of being- 
 wound 5 when wrapped round such cylinder, it will, by its 
 
14 
 
 THE OPERATIVE MECHANIC 
 
 upper edge B C, represent spiral lines, similar to B D 
 and F G. Now, as the piece ABC is in the shape of a 
 wedge or inclined plane, it should have its power esti- 
 mated by the line A C compared to the height A B ; 
 and if the line B C, wound in its spiral direction, shall 
 just circumscribe the cylinder, the point C will be found 
 directly beneath B, and the distance between C and B, when 
 thus lapped on the cylinder, will represent the line A B, on 
 the perpendicular of the inclined plane or wedge ; which, when 
 compared with A C, now represented by the circumference 
 of the cylinder, will give the same data from which the 
 power of the screw, so formed, should be calculated. Con- 
 sequently the comparison of the circumference of the screw, 
 and the distance between one thread and another, measured 
 on a line parallel to the axis of the screw, is that from which 
 its power should be calculated, or as the distance between 
 the two threads is to the circumference, so the power to be 
 applied is to the resistance to be overcome ; or if the 
 circumference be three, and the power one, the force equal 
 to one shall overcome a force equal to three. 
 
 Fig. 24 represents a screw of more perfect formation ; 
 but the general construction of the screw is so familiar to 
 every one, that we conceive it to be almost needless to 
 enter upon a more minute description. A B represents the 
 acclivity of the plane from which such screw is formed, and 
 the distance between B and C represents what should be 
 compared to the circumference in order to discover the 
 power it possesses. 
 
 The screw is applied to mechanical purposes chiefly to 
 obtain great pressures in small distances; and upon exa- 
 mination it will be seen, that they afford a method of using 
 a wedge of an extremely small inclination, and by con- 
 sequence of great power. The screw is sometimes used 
 for raising exceedingly heavy weights. The hollow screw, 
 or the counterpart in which a screw operates, when in the 
 form of a small movable piece, is called a nut, and the cavity 
 is termed a female screw, the properties of which are, as 
 respects power, exactly similar to the screw. 
 
 We have now duly considered the nature and properties 
 of the mechanical powers when in a state of uncombined 
 action ; and shall, in the next place, previously to repre- 
 senting them in some of the simplest forms in which they 
 are combined, examine into one more attribute of matter, 
 resulting from gravity. 
 
AND MACHINIST. 
 
 15 
 
 THE CENTRE OF GRAVITY. 
 
 The force of gravitation, as we have already shown, acts 
 upon matter in proportion to its quantity : thus, if a line be 
 drawn through any body in such manner, that the quantity 
 of matter multiplied into its distance from the line on one 
 side shall equal the quantity of matter multiplied into its 
 distance on the opposite side, and if another line be drawn 
 passing through the body in another direction, dividing it 
 in a similar manner, the point where those two lines meet, 
 whether it be situated within or about the body, is the 
 centre of gravity ; and if that point or centre, supposing it 
 within the body, be supported, the body will remain in a 
 state of equilibrium. Suppose the body D, fig. 25, to be 
 suspended by a line from C, then the point H, which is 
 called the point of suspension, and at which the body is 
 suspended in a state of rest, will be directly above the 
 centre of gravity. For if the perpendicular line H I be drawn, 
 and the quantity of matter multiplied into the distance on 
 one side of the line be not equal to the quantity of matter 
 multiplied into the distance on the other side, the body will 
 not be at rest ; but as the body is at rest, the quantity of 
 matter multiplied into its distance on the one side, is exactly 
 equal to the quantity of matter multiplied into its distance 
 on the other. Again, suspend the body as at fig. 26, and let 
 a perpendicular fall similarly from K, the point of suspension, 
 to L, the body will be again divided in like manner, and 
 the point E, where the perpendicular K L intercepts the line 
 H I, will be the centre of gravity. 
 
 If any force acting in a direct line pass through the 
 centre of gravity of a body, it will produce uniform motion in 
 that body ; but if the force so impressed do not pass through 
 the centre of gravity, that motion will be unequally com- 
 municated. Thus, if at fig. 26, M I represent a force 
 striking the irregularly shaped body D, in a line of direction 
 passing through its centre of gravity E, the force so impressed 
 on that body will cause it to proceed with a uniform velocity, 
 as regards all its parts ; but should the force M I be impressed 
 at the point F, as M 1 , the line of direction not being through 
 the centre of gravity, an irregular motion will be communi- 
 cated, and the body will acquire a revolving motion round its 
 centre of gravity. 
 
 As the centre of gravity is the most advantageous point for 
 
IG 
 
 THE OPERATIVE MECHANIC 
 
 giving to a l)ody uniform motion, so also it is the best to 
 apply resistance to arrest the progress of that motion. 
 
 Most writers on Mechanics speak of the common centre of 
 gravity as of more than one body, or as a system of bodies ; 
 but as they mean that those bodies should be conjoined, or 
 their relative position maintained by some force, they may 
 properly be considered as but one body, and the centre of 
 gravity of the whole assemblage may be estimated in a 
 similar manner to that of one. Thus, if the bodies A and B, 
 hg. 27 , be conjoined by a line, their common centre of 
 gravity will be the point E ; for if a line be drawn through 
 that point in any direction, the masses of matter, multiplied 
 into their respective distances on each side, will equal each 
 other. 
 
 What has been said concerning the centre of gravity, is 
 also applicable to practical points ; as no body can be sup- 
 ported in a state of equilibrium, if the point of suspension 
 be not exactly above or beneath its centre of gravity 
 
 SIMPEE COMBINATIONS OF THE MECHANICAL POWERS. 
 
 Having considered the capacities of the mechanical powers, 
 and the modes used for calculating their effects, we will 
 now turn our attention to them in a state of combination ; 
 and as all of these instruments are in themselves gainers of 
 power, power must be considerably increased when they 
 become adjuncts to each other. Thus, in fig. 28, we have 
 a combination of three levers, each of them, by the dis- 
 proportion of their arms, gainers of power as three to one ; 
 G G G being their several fulcrums, the weight H will 
 operate with thrice its power at B, by means of the lever 
 A B ; the effect will be again trebled by C D ; and that 
 amount again trebled by the action of the lever E F. Con- 
 sequently, if we call H one, by A B it will be raised to three, 
 by C D to nine, and by E F to twenty-seven ; so that a 
 weight of one pound at A will support twenty-seven pounds 
 at F. 
 
 The combination of the action of levers may thus be ex- 
 tended to the gain of almost any amount of power ; and 
 when bent levers are introduced, their powers, which in 
 peculiar situations have been shown to be very great, may in 
 like manner be multiplied. 
 
 The wheel and axle is an implement not frequently used in 
 its simple state. In machinery, wheels are mostly turned 
 by means of prominences upon their peripheres, called 
 
AND MACHINIST. 
 
 17 
 
 cogs, or teeth, which being acted upon by any applied force, 
 cause the wheel to revolve ; and the axle being similarly fur- 
 nished with teeth, or cogs, is termed a pinion. The wheel 
 and pinion, therefore, bear a similar relationship to each other 
 as the wheel and axle, and their power must be calculated in 
 the same manner. Suppose A B, fig. 29, to be a shaft on 
 which the handle A C, of twelve inches radius, and the pinion 
 
 D, of one inch radius, are fixed 5 and the teeth of the wheel 
 
 E, of twelve inches radius, acting in those of the pinion D, 
 and upon the shaft of E is fixed the pinion F, of one inch 
 radius, communicating with the wheel G, of twelve inches 
 radius, upon the shaft of which the pulley H, of one inch 
 radius, is fastened ; we shall then have the handle A C repre- 
 senting the radius of a wheel, and the pinion D in the situa- 
 tion of the axle ; so that there will be a gain of twelve to one : 
 and the wheel E, bearing the same proportion to the pinion F, 
 will also gain in a similar ratio, and G being to H, as* E to F, 
 the gain will again be augmented to the same extent ; so a force 
 equal to one at C will operate as twelve at D ; and twelve at 
 D will operate as a hundred and forty-four at F ; and at H as 
 seventeen hundred and twenty-eight. Thus one pound at 
 C will raise seventeen hundred and twenty-eight pounds at 
 H, and the handle C will have to pass through seventeen 
 hundred and twenty-eight times the distance through which 
 the weight I will move. By this form and disposition of 
 wheels and pinions, an accession of power is obtained ; but if 
 velocity be required at the expense of power, this train 
 should be inverted. For, if we suppose the pulley H to be 
 turned by a force so as to cause the weight I to pass through 
 one foot, the periphery of the wheel G will have passed 
 through twelve feet, and the periphery of the pinion will have 
 gone through the same distance ; but the wheel E being 
 twelve times the diameter of F, it will have passed through 
 twelve times that distance, or a hundred and forty-four feet ; 
 and the pinion D, in like manner, will cause C to pass through 
 twelve times that amount of space, or seventeen hundred 
 and twenty- eight feet ; whilst the force required at H to 
 cause this motion, must be seventeen hundi’ed and twenty- 
 eight times the resistance at C. 
 
 As the circumferences of wheels are proportionate to the 
 circumferences of the pinions they have to act upon, or be 
 acted upon by, so must the number of teeth in the one be 
 to those in the other, otherwise the size of the teeth would 
 not be similar ; thus, a wheel that is twelve inches diameter, 
 and a pinion one inch, the circumferences of circles being 
 in proportion to their diameters, the wheel should have 
 
 c 
 
18 
 
 THE OPERATIVE MECHANIC 
 
 twelve times as many teeth as the pinion, therefore, in prac- 
 tice, the number of teeth may be taken as data to estimate 
 the power or velocity. Suppose a pinion has five teeth, and 
 a wheel sixty, their power will be as twelve to one, as five 
 will go twelve times in sixty; that is, the pinion will 
 have to turn twelve times to move the wheel once ; and if 
 turned by a handle A C, whose radius is equal to the wheel, 
 the power gained will be in the same ratio ; and if the 
 pinion is driven by the wheel, the velocity obtained will, in 
 like manner, increase ; consequently the velocities, or powers 
 of any combination of wheels, may be estimated by their dia- 
 meters, circumferences, or number of teeth. 
 
 Although this mode of communicating motion is used to 
 a very great extent in applying wheel-work to machinery, 
 yet, in peculiar cases, straps, chains, and cordage, of vari- 
 ous descriptions, are beneficially introduced to transfer the 
 action of wheels. 
 
 Combinations of the wedge are not very common : but 
 its properties are introduced under several modifications, 
 and afibrd methods of obtaining power of considerable pres- 
 sure in short distances. For instance, that common and 
 well-known part of mechanical construction, called the 
 camb, or eccentric, is a wedge applied by one of its faces to 
 a cylinder, which, by being turned by means of a lever, is 
 capable of producing a powerful action. Fig. 30 represents 
 a cylinder A, with a wedge B wound round it, but which, in 
 this position, is denominated a camb, or eccentric piece ; by 
 the motion of the lever C to the situation Cl, the cylinder 
 A, with the camb B, is brought into the position B 1 ; thereby 
 raising the obstacle D to D 1. The power gained in this 
 operation may be ascertained thus ; as the length of the lever 
 C from the center of A exceeds the radius of A, so will the 
 force applied at C be increased, at the point E, where it may 
 be supposed to act, against the wedge or camb B ; and the 
 effort to raise D may be known by considering the proportion 
 of E F to E H, which is the portion of the circumference that 
 must be considered as its base. Thus, if we call the length 
 of the lever C three, and the radius of A one, if the force 
 acting at C be one, its power at E will be three; and should 
 the height E F be one third of the base of the camb B, 
 this power will be again raised by three ; thus, 1 at C will 
 counterbalance 9 at D This movement is extremely com- 
 mon in order to obtain power, or a regular direct motion. 
 It is quicker than a screw, and capable of considerable 
 accuracy. 
 
 Fig. 31 is another modification of the wedge, placed on 
 
AND MACHINIST. 
 
 19 
 
 the internal face of the circle E, acting with its face F, 
 and causing by its movement the obstacle I to approach 
 nearer to the centre G ; this is called the snail movement^ 
 and might with propriety be termed a concentric. 
 
 Another method of placing a wedge, so as to apply its 
 effects to a revolving motion, is represented in a side and 
 top view at fig. 32, where the w^edge A B is placed upon a 
 circular plate C D, turning upon the axis E, and conse- 
 quently creating motion in the obstacle upon which it acts 
 to the amount of the line G A. 
 
 Another movement of considerable accuracy is obtained 
 by the turning of a cone, the principle of whose action is 
 referable to the wedge. Fig. 33 represents a cone fixed 
 upon its axis ^ k. If an obstacle he presented at a, and the 
 cone be caused to pass forward in the direction ki, the 
 surface a c will operate as a wedge at a b c, raising the 
 obstacle to c ; but if during that direct motion the cone is 
 likewise caused to revolve on its axis, the obstacle, instead of 
 passing over ac, will pass over the spiral line aegd, to the 
 point d; by this means the operation of a wedge, whose line 
 of inclination is equal to the spiral line a e g d, and w’hose 
 height is equal to b c, is brought into action ; and if the 
 number of revolutions of the cone be increased during its 
 direct motion, it is plain that the effect of a wedge of 
 infinite elongation may be produced. 
 
 The screw is introduced both singly and in a state of combi- 
 nation in many parts of machinery. The combined action of two 
 screws, which avoid the necessity of using a screw of greater 
 fineness, in which the threads would be weakened, is repre- 
 sented at fig. 34, where they are applied to a press. Suppose 
 A A to be a screw’ fitted in a female screw in the rail B C; 
 and D, a screw that w’orks in the inside of A, having its 
 lower end joined to the upper board of the press H, so that 
 it shall not turn round : now if the screw A A, and the screw 
 D, contain exactly the same number of threads in the inch, 
 by turning A A one revolution, it will proceed downwards 
 exactly the same amount that the screw D will, by the same 
 action, proceed upwards, and the board H will not be moved. 
 But we will suppose that the screw A A contains four threads 
 in the inch, and the screw D six, then, by one revolution, 
 A A will move downwards one quarter of an inch, and D will 
 at the same time, and by the same action, be raised one- 
 sixth of an inch, therefore the board H will move downwards 
 the difference between one quarter and one-sixth, or one- 
 twelfth part of an inch,, by every single revolution : which 
 
20 
 
 THE OPERATIVE MECHANIC 
 
 effect is similar to that which would be produced by using 
 a screw of twelve threads to the inch. 
 
 For further elucidation we shall refer the action of each 
 screw to that of a wedge from which the screw has been 
 shown to be derived Fig. 35 represents two wedges^ a b h 
 and ec each of which may be supposed to represent one 
 lap of a screw of the respective fineness which their heights 
 h h and e c denote. If the wedge ah h be caused to pass 
 to the situation a’ a and is supposed to operate upon the 
 level surface c/,the line ae will be compressedto the line Id c, 
 by that movement; but if^ whilst this action takes place, the 
 wedge e c c/ be moved to the position c, and the effect 
 takes place upon its upper surface e d, the line a e will only 
 be reduced to the line e, equal to h d, and will conse- 
 quently only be compressed to the amount a, which is in 
 effect equal to what a wedge of the fineness oi ah g would 
 have produced, whose height or line ^ 5 is just equal to the 
 difference between e c and h h, as was the case with the screws. 
 
 As a gain of power is attainable by two screws or 
 w'edges of unequal fineness, performing equal numbers of 
 revolutions, so is the same effect attainable by the unequal 
 revolutions of two screws or wedges of equal fineness. 
 
 MILL GEEPJNG. 
 
 Under this head w^e purpose to treat of the best form- 
 ation of the teeth of wheels, of the coimection of shafts, 
 termed couplings, of the disengaging and reengaging of 
 the moving parts, and of the equalization of motion ; and to 
 them we shall annex some further observations upon the 
 general construction of Machinery. To avoid unnecessary 
 repetition, we shall, previously to entering upon the form- 
 ation of the teeth of wheels, give a general definition of the 
 terms most commonly in use. 
 
 Cog-wheel is the general name of any wheel which has a 
 number of teeth or cogs placed round its circumference. 
 
 Pinion is a small cog-wheel that has not in general more 
 than twelve teeth ; though, when two-toothed wheels act upon 
 one another, the smallest is not unfrequently distinguished by 
 this term ; as is also the trundle, lantern, or wallower, when 
 talking of the action of two wheels. 
 
 Trundle, lantern, or ivalloiver, is sometimes used in 
 lieu of a pinion. It is represented at fig. 36. 
 
AND MACHINIST. 
 
 21 
 
 When the teeth of a wheel are made of the same material, 
 and formed of one piece with the body of the wheel, they 
 are called teeth ; when of wood, or some other material, and 
 affixed to the outer rim of the wheel, cogs; in a pinion 
 they are called leaves ; in a trundle staves. 
 
 When speaking of the action of wheel-work in general, 
 the wheel which acts as a mover is called the leader, and 
 the one upon which it acts the follower. 
 
 If a wheel and pinion are to be so constructed that the 
 one shall give, and the other receive, impulse, so that the 
 pinion shall perform four revolutions in the time that the 
 wheel is performing one, they must be represented by two 
 circles, which are in proportion to each other as four is to 
 one. When these two circles are so placed that their outer 
 rims shall touch each other, a line drawn from the centre of 
 the one to the centre of the other is termed the line of 
 centres; and the radii of the two circles the proportional 
 radii. These circles are sometimes called proportional 
 circles, but by mill-wrights in general pitch lines. 
 
 The teeth which are to communicate motion must be 
 formed upon these two circles. The distance from the cen- 
 tres of two circles to the extremities of their respective teeth, 
 is called the real radii; and, in practice, the distance be- 
 tween the centres of two contiguous teeth, that is, the dis- 
 tance from the centres of two teeth measured upon their 
 pitch line, is called the pitch of the ivheel. The straight part 
 of a tooth which receives the impulse is called the flank, and 
 the curved part that imparts the impulse, the face. 
 
 Two wheels acting upon one another in the same plane, 
 having their axes parallel to each other, are called spur geer ; 
 when their axes are at right, or other angles, bevelled geer, 
 
 TO DESCRIBE THE CYCLOID AND EPICYCLOID. 
 
 Fig. 37 . If the circle 1, having a point a marked on its 
 circumference, moves along the straight line A C, and at the 
 same time revolves on its axis, the curved line which the point 
 a describes is called the cycloid. The point a in circle 1 is 
 at its starting place, at B it has reached its greatest height, 
 and at C its lowest depth ; and the curved line ABC described 
 by that point, is the cycloid. 
 
 Fig. 38. If the circle 1 rolls on another circle, as on the 
 circumference of circle 2, the point a describes, in a similar 
 manner to the preceding, the curve a g h d e, and the circle^ 
 3, 4, 5, 6, exhibit the point a in the several positions of a\ 
 a?, ca^ the portion of circle 3 being equal to c a, c*® 
 
22 
 
 THE OPERATIVE MECHANIC 
 
 to c® a, c’ to c'^ a, and to c** a : the line which is 
 
 thus described is called an exterior epicycloid. But if the 
 circle rolls within another circle, as the circle 1, fig. 39, rolls 
 in the inside of circle 2^ the line described by the point a 
 is then called an interior epicycloid. 
 
 In fig. 38, the circle a m n is called the generating circle 
 of the epicycloid^ and that portion of the larger circle over 
 which the generating circle rolls in one revolution the base 
 of the epicycloid. In the interior epicycloid the generating 
 circle of the epicycloid rolls within the circle of its base. 
 
 An epicycloid, either internal or external, may be conceived 
 to be formed of numerous small portions of circles, whose 
 radii are lines drawn from the several points of contact, as 
 c, c®, c^y c being the centre of one, c® of another, and 
 the centre of another, so that these lines are, as respects those 
 several positions, radii of each circle, and perpendiculars to 
 the epicycloid j if, therefore, a line be drawn from any point 
 where the generating circle is in contact with the base to the 
 point which traces the epicycloid, it will fall perpendicular 
 to the epicycloid. 
 
 As the several lines drawn from the points of contact of the 
 generating circle are, in all cases, the varying radii for gene- 
 rating the epicycloid, it is plain that when the generating cir- 
 cle shall have passed over half of its base, and consequently 
 have performed half of a revolution, the diameter of the ge- 
 nerating circle shall be a line drawn from the point of con- 
 tact to the generating point, and which line shall, if prolonged, 
 pass through the centre of the circle of the base, so that the 
 tracing point in that part of the epicycloidal line shall be far- 
 ther from, and in all other points nearer to, the base, as the 
 perpendiculars that fall upon the epicycloid from the points of 
 contact shall in every other position be shorter. Suppose the 
 circle 1, fig. 40, to be a generating circle, and circle 2 to be 
 the circle of the base, if the diameter of circle 1 be equal to 
 the radius of circle 2, the point a shall trace the line a i6 c as 
 an interior epicycloid ; for if the diameter of circle 1 be equal 
 to half of the diameter of circle 2, so will the circumference 
 of circle 1 be equal to half of the circumference of circle 2, 
 and consequently, when the generating circle 1 shall have 
 performed one revolution upon the circle 2, as its base, the 
 point a shall be exactly opposite to the place from where it 
 started ; now the diameter of circle 1 is equal to the radius of 
 circle 2 when half way, and the tracing point is exactly in the 
 centre of circle 2, which proves, that the epicycloid traced 
 by the circle 1 is a straight line, and the diameter of circle 2, 
 
(&JEEIE.WO 
 
 From J6' to 40 
 
AND MACHINIST. 
 
 23 
 
 ON THE TEETH OF WHEELS. 
 
 If two cylinders be placed in close contact, motion cannot 
 be communicated to the one without that motion, by means 
 of the irregularities of their surfaces, (of which we have spoken 
 under the article Friction,) being communicated to the other, 
 and the smaller cylinder shall perform exactly as many revolu- 
 tions to one revolution of the larger cylinder, as the larger 
 cylinder contains upon its circumference so many measured 
 circumferences of the smaller cylinder. 
 
 Wheels, however, which act by their surfaces only, are ill- 
 calculated to transmit motion to any considerable extent, as 
 the motion which the follower has acquired is not of sufficient 
 power to overcome the great resistance which would, in such 
 case, be opposed to it ; consequently it becomes necessary to 
 have projections or teeth, and that form of the teeth will be 
 the best which causes the wheel to act as though the motion 
 were communicated by contact of the pitch lines. 
 
 Spur geer, fig. 39*. If the three circles 1, 2, 3, in contact 
 at the point a, be made to revolve about their centres, so that 
 they shall continually touch at the point «, their motions will 
 be similar to what would have been generated by one com- 
 municating motion to the other two by contact ; and circle 3 
 will move as though rolling on the external surface of circle 1, 
 and internal surface of circle 2, and consequently become the 
 generating circle of the exterior epicycloid on circle 1, and the 
 generating circle of the interior epicycloid on circle 2. As the 
 diameter of circle 3 is equal to the radius of circle 2, the in- 
 terior epicycloid will be a straight line passing through B the 
 centre of circle 2 ; and, supposing the point a to have per- 
 formed that portion of a revolution which places it at K, a 
 portion of the exterior epicycloid will be represented by the 
 line E K, and a portion of the interior epicycloid by D K. 
 Therefore, as the epicycloids D K and E K are both generated 
 by one motion of the same point on the same circle, they will 
 continually touch at the generating point, and the total sur- 
 face of E K will pass over the total surface of D K ; and if 
 the epicycloid E K be affixed to the external surface of cir- 
 cle 1, and act upon the portion of the epicycloid .D K, it will 
 transmit motion to circle 2, as though that motion were com- 
 municated by contact of the pitch lines \ which proves that 
 E K presents us with the best form of tooth, and which tooth 
 would, when acting upon the radii of the wheel to be driven, 
 move it as though the motion wei'e communicated by contact. 
 
24 
 
 THE OPERATIVE MECHANIC 
 
 Fig. 40=* represents a mode of forming the teeth of wheels 
 wlien they are to act upon a trundle. Circle ] represents the 
 pitch line of the wheel ; and circle 2 the pitch line of the trun- 
 dle ; which are supposed to act by contact at the point 
 When a arrives at a*, it will have traced that portion of an 
 epicycloid represented by a* and as a is the generating 
 point of the epicycloid^ the distance from a to from 
 
 a to will be equal : and the epicycloid bein^ ge- 
 
 nerated by the proportional circle or pitch line of the trundle, 
 presents us with the properest form for the tooth of a wheel 
 that is to drive a trundle with circular staves posited in its 
 pitch line. 
 
 We shall now proceed to the practical mode of applying 
 these rules. Let circle 2 be the proportional circle or pitch 
 line of a trundle ; and circle 1 the pitch line of a wheel which 
 is to drive that trundle ; and by the revolutions of these two 
 circles let the portion of an epicycloid be generated, 
 
 so that when a line is drawn from to the centre of circle 1 , 
 it will intersect that circle at Z>, whose distance from is 
 such, that when the semi- diameter of a staff of the trundle 
 is subtracted from it, the remainder will be equal to half the 
 intended thickness of the tooth of the wheel. Set off per- 
 pendicularly to the epicycloid inwards, the semi-diameter of 
 one of the staves at so many points that you will be able to 
 trace through the points thus set off, a line parallel to the 
 epicycloid which line will be the face of the tooth of 
 
 the wheel, being less than the tooth formed by the epicy- 
 cloid by the semi-diameter of a staff of the trundle, 
 
 indeed the diminution must be rather more, as the width 
 g g must be made sufficient for the staves to clear them- 
 selves, as the whole of the epicycloidal line must act upon 
 their surface. 
 
 Fig. 41. To describe the teeth of a wheel for a trundle, 
 by means of circular arcs, let us suppose A B to be the line of 
 centres, C D the pitch line of the wheel, E F the pitch line ci 
 the trundle, and the centre of the staff’ G to be in the line of 
 centres A B ; then by placing one foot of the compasses in 
 the centre of the staff G, we can describe the arc m n, which 
 is the form of the face of a tooth sufficiently near that of an 
 epicycloid for common purposes. 
 
 Fig. 42. To find the form for the teeth of a wheel and the 
 leaves of a pinion which are to act together, we must set off on 
 the pitch lines the points m n a, and p q r, &c., according to 
 the proper thickness of and distance between the teeth and 
 leaver, and from these points draw radii, to serve as the 
 
AND MACHINIST. 
 
 25 
 
 flanks of the teeth. The spaces must be of sufhcient depth to 
 allow for the action of the curved part of the teeth and leaves. 
 
 Then with the generating circle 1, whose diameter is equal 
 to the proportional radius of the pinion, describe upon the 
 extremities of the sides of each tooth, and upon the circum- 
 ference of the proportional circle of the wheel as a base, the 
 epicycloids a Z>, 5 n; and with the generating circle 2, describe 
 upon the proportional circle of the pinion as a base, the epi- 
 cycloid q I), which will give the required form of the teeth 
 and leaves. 
 
 For if the projecting epicycloid a h push against the ra- 
 dius /r of the proportional pinion, the wheel and pinion will 
 move with equal velocity ; and a similar effect will be produced 
 by the epicycloid p D being pushed by the radius o m of the 
 wheel towards the line of centres. 
 
 Fig. 43. When one wheel is to conduct another, it is not 
 necessary that the wheel to be conducted should have teeth 
 of an epicycloidal form ; and were the teeth not- subject to 
 w'ear by friction, there would be no occasion to extend the 
 teeth of the conducted wheel beyond the pitch line ; but such 
 being the case, it becomes necessary to form the teeth of the 
 conducted wheel in the manner represented in the figure by 
 the dotted lines. 
 
 Mr. Buchanan, in his Essay on the Teeth of Wheels,’ ' 
 objects to this mode of forming the teeth of the conducted 
 wheel, and recommends that a trundle or wheel with cylin- 
 drical staves should be adopted, as it will be less acted upon 
 in approaching the line of centres, and consequently have less 
 friction than a pinion or wheel, the sides of whose teeth tend 
 to the centre. 
 
 This will appear,” says he, by fig. 44, which repre- 
 sents a staff, «, of a trundle, and a leaf, h, of a pinion, 
 turning round on the same centre A, and a tooth adapted to 
 each, turning on a common centre B. The thickness of each 
 of the teeth, and the proportional circle of both wheels, are 
 the same, and the proportional circles of the pinions are also 
 equal, and teeth are each made of the greatest length which 
 the intersection of the curves will admit, which turns out con- 
 siderably greater in the tooth adapted to the staff. The shaded 
 parts represent the tooth adapted to, and acting upon, the 
 staff ; and the dotted lines represent the tooth adapted to, 
 and acting upon, the leaf. The teeth, in both cases, are re- 
 presented as just at the point where they would cease to 
 move the leaves or staves uniformly; and it appears the staff 
 
26 
 
 THE OPERATIVE MECHANIC 
 
 is conducted considerably further beyond the line of centres 
 than the leaf ; hence the staff will be less acted upon in 
 approaching the line of centres.” 
 
 As the trundle in common use is very weak and imperfect, 
 Mr. Buchanan conceived, that a wheel might be made, which 
 would combine the advantages of both the pinion and trun- 
 dle, and accordingly had some wheels made, which appeared 
 to answer every expectation. 
 
 These wheels,” says he, were made of cast iron. They 
 were each cast of one solid mass. Fig. 46, No. 1, repre- 
 sents the edge view, and No. 2, a section of one of them; 
 whereby is shown the manner in which the teeth are sup- 
 ported, like the staves of a trundle at each end, and like the 
 leaves of a pinion at the roots, but so very thin there, as to’ 
 run no risk of having the common fault of pinions, just now 
 noticed. They were difficult to mould : but were they to 
 come more into use, I have no doubt ingenious workmen 
 would soon get over this obstacle.” * “I mentioned,” he 
 continues, ‘‘ in cases Avhere the pinion had few teeth, that in 
 the conducted, whether wheel or pinion, staves should be pre- 
 ferred; but it is obvious, that the method just described, 
 of making a small trundle of cast iron, would not apply to a 
 wheel of a great number of staves. Nor is it in that case so 
 necessary, as the greater the number of teeth are, the longer 
 they will be in losing their proper figure. In such cases, 
 therefore, staves, strictly speaking, should not be used, but 
 teeth made so as to produce the same effect — -that is, having 
 their acting parts of the figure of a staff. What is meant 
 will be better understood by inspecting fig. 46, where the 
 lines show the alteration necessary on the tooth A, in order 
 to make it produce the effect of a staff ; which staff is repre- 
 sented by the faint dots. The dotted lines on d represent 
 the alteration requisite to adapt it to the staff, it being neces- 
 sary, as formerly proved, to have it a different epicycloid from 
 what is required to adapt it to a tooth whose acting part is a 
 straight line, tending to the centre of its proportional circle.” 
 
 ‘‘ Teeth,” says Mr.Tredgold, in the second edition of Mr. 
 Buchanan’s work, seem to be very well adapted for va- 
 
 ^ By casting separate plates with indents to fix the teeth, and bolting 
 them together, the pinion might be made sufficiently strong : such a method 
 indeed is used frequently in crane-work, where it has the important advan- 
 tage of preventing the wheels getting out of geer. 
 
 N. B. This note is by Mr. Tredgold, editor of the second edition of Bu- 
 chanan’s “ Practical Essays on Mill- work.” 
 
MJGLIL (^EJElipi^G 
 
 From 40 to JJ. 
 
 Pl.-t. 
 
 f 
 
AND MACHINIST. 
 
 27 
 
 rioiis purposes, when formed on the principle recommended 
 in the preceding article. I therefore will endeavour to show 
 a simple method of describing such teeth. 
 
 ‘‘ It must be observed, that the teeth to resemble staves are 
 to be always on the conducted wheel or pinion ; thus afford- 
 ing the peculiar advantage of the wheel and trundle in either 
 increasing or diminishing velocity. 
 
 Fig. 38=^. Let the teeth be divided as usual on the pitch 
 lines, EE, F F 3 and on the conducted wheel C describe cir- 
 cles, as though there were to be staves. Conceive the centre 
 of one of these staff teeth to be in the line of centres at A, 
 and draw the line A B joining the centres of the staff teeth. 
 Then the radius A Z>, from the centre A, will describe the 
 curved side h c oi the tooth of the conductor, and the curved 
 part ba oi the conducted wheel. And since this radius is 
 equal to the pitch diminished by half the diameter of the cir- 
 cle of the staff teeth, and the centres will always be in the 
 pitch lines of the wheels, all the other teeth may be easily 
 described."' 
 
 The editor then enters into some calculations, which the 
 limits of our work will not permit us to pursue, we therefore 
 refer our readers to the work itself, which embraces much 
 useful information. 
 
 Fig. 47. When a pinion is required to have but a slow 
 motion, an internal pinion, which has less friction than the 
 external one, may, in many cases, be adopted with advantage. 
 
 To illustrate this, let A, fig. 48, be the proportional circle 
 or pitch line of a wheel, B that of an external pinion, and C 
 that of an internal pinion, all at contact at the point a : now, 
 if motion be communicated to the wheels, so that they 
 move uniformly, it will be seen, that when the point a has 
 arrived at bed, each of the wheels having travelled over an 
 equal distance from the line of centres D, the space from btoc 
 is much less than that from c to d, and consequently had the 
 wheels moved by means of teeth, the tooth of the internal 
 pinion C would have slid over a smaller part of a tooth of the 
 wheel A, than a tooth of the external pinion B, wdiich proves 
 it would have had le^s velocity and less friction. 
 
 Fig. 49 represents a rack and pinion, recommended by 
 Mr. Tredgold. A B the pitch line of the rack, B C the 
 pitch line of the pinion, and the form of the tooth C D is 
 the involute of a circle ; but when the rack impels the 
 pinion, the curved face of each of the teeth of the rack 
 should be a portion of a cycloid, (as A, a, fig. 37,) and the 
 leaves of the pinion straight lines radiating from the centre 
 
38 THE OPERATIVE MECHANIC 
 
 of the pillion ; the diameter of the generating circle for 
 describing the cycloidal teeth should be half the proportional 
 diameter of the pinion. See Buchanan" s Practical Essays 
 on Mill-work, Tredgold’s edition. 
 
 Bevel geer. — We have already stated^ that when the axes 
 of wheels are angular to each other^ they are called 
 bevel geei% in order to distinguish them from spur geer, 
 whose axes are parallel •, it therefore now remains for us 
 to describe in what manner the teeth of bevel geer differ 
 from the teeth of spur geer. 
 
 Bevel geer is represented by the two cones at fig. 50, 
 where A B and B C are the axes, and D E and £ F their 
 proportional diameters or pitch lines. 
 
 If these two cones are placed in close contact, and motion 
 is communicated to the one, that motion will, as is already 
 stated, be communicated to the other, and the motion of 
 both, as w^e have shown, when speaking of spur geer, 
 will be equal. 
 
 The epicycloid for forming the teeth of bevel geer, is 
 generated by one cone rolling upon the surface of another, 
 while their summits coincide : for example, if a cone C, 
 fig. 51, having a point a, move upon the surface of the 
 cone D, the point a will, in its revolutions, describe the 
 line A E F, A being the place from where it starts, E its 
 greatest height, and F its lowest depth ; therefore a curved 
 line drawn from A to E, and continued from E to F, 
 gives what is called a sj^lierical epicycloid ; and the base 
 of the cone C is the generating circle of the spherical 
 epicycloid. The method of using the spherical epicycloid 
 for forming the teeth of bevel geer is, in every respect, 
 similar to the method of using the exterior and interior 
 epicycloid for forming the teeth of spur geer, consequently it 
 wall be needless to repeat it. 
 
 Fig. 52. To construct bevel geer we must calculate the 
 proportional diameters or pitch lines of the wheel and 
 pinion that are to act upon each other, and then draw 
 their axes AB and B C. Draw parallel to the axis AB 
 of the wheel the line D E, and the line F D parallel to 
 the axis of the pinion, and from the point D, where these 
 tw'o lines intersect, draw the line D G perpendicular to 
 A B, and D H perpendicular to B C, and make 1 G equal to 
 D I, and K H equal to D K 5 then D G gives, what is called 
 the principal diameter, or diameter of the pitch line of the 
 %vheel, and D FI that of the pinion. 
 
 Froceed to draw the teeth of the w'heel, by fixing onq 
 
AND MACHINIST. 
 
 29 
 
 foot of the compasses in the point at A, and^ having ex- 
 tended the other foot to the distance sweep the small 
 arc G then set off the length of the tooth from G to /;, 
 draw the line h c, tending to a, and sweep the arc c e, con- 
 centric to h a. Set off from G to / part of the required 
 length of the toothy from the principal diameter to the root ; 
 and draw the line f g tending to A, which gives the root 
 of the tooth. Parallel to fg, draw ae, and cifge will 
 represent a section of the solid ring of the wheel. 
 
 In an excellent article on mill-work^ in Dr. Rees’s Cyclo- 
 pedia^ the author states^ that the manner of setting out 
 the teeth of cog-wheels, in such a form that they shall act in 
 the most equable manner upon each other, and with the 
 least friction, has been a subject of much investigation 
 among mathematicians and theoretic mechanics ; but the 
 practice and observation of the mill-wrights have produced a 
 method of forming cog-wheels, which answers nearly, if not 
 fully, as well in practice, as the geometrical curves which 
 theory has pointed out to be the most proper. This they 
 have effected by making the teeth of the modern wheels ex- 
 tremely small and numerous. In this case, the time of action 
 in each pair of teeth is so small, that the form of them be- 
 comes comparatively of slight importance ; and the practical 
 methods of the mill-wrights (using arcs of circles for the 
 curves) approximates so nearly to the truth, that the dif- 
 ference is of no consequence : and this method is the best, 
 because it so easily gives the means of forming all the cogs 
 exactly alike, and precisely the same distance asunder, which, 
 by the application of any other curve than the circle, is not 
 so easy. The method, which is extremely simple, is explained 
 in lig. 53. The wheel being made, and the cogs fixed in 
 much larger than they are intended to be, a circle, a «, is 
 described round the face of the rough cogs upon its pitch 
 diameter, that is, the geometrical diameter, or acting line of 
 the cogs ; so that when the two wheels are at work together, 
 the pitch circles, a a, of the two are in contact. Another 
 circle, b b, is described within the pitch circle for the bottom 
 of the teeth, and a third, dd, without it, for the extremities. 
 After these preparations, the pitch circle is accurately di- 
 vided into the number which the wheel is intended to have ; 
 a pair of compasses are then opened out to the extent of one 
 and a quarter of these divisions, and with this radius arcs are 
 struck on each side of every division, from the pitch line a, 
 to the outer circle d d. Thus the point of the compasses 
 being set in the division e, the curve f g, on one side of the 
 
30 
 
 THE OPERATIVE MECHANIC 
 
 cog, and no on one side of the other, are described ; then 
 the point of the compasses being set on the adjacent divi- 
 sion k, the curve I m is described. This completes the 
 curved portion of the cogs c, and this being done all round 
 completes every tooth ; the remaining portion of the cog 
 within the circle a, is bounded by two straight lines drawn 
 from the points g and m towards the centre ; this being 
 done to the cogs all round, the wheel is set out, and the cogs, 
 being dressed or cut down to the lines, will be formed ready 
 for work, every cog being of the same breadth ; and the space 
 between every one and its neighbour is exactly equal to the 
 breadth, provided the compasses are opened to the extent of 
 one division and a quarter as first described.’^ 
 
 COUPLINGS. 
 
 Coupling boxes are used to connect the shafts of wheels ; 
 they are either round or square, and with single or double 
 bearings. The square coupling with double bearings, is 
 represented in fig. 54, where B, between the bridges C D, 
 is a square shaft with the coupling box resting upon it, ready 
 to be thrust, when occasion requires it, upon the shaft A, 
 which is out of geer, and to which it can be fastened by means 
 of a pin, as shown at F, where the shafts are in geer. The 
 round coupling, represented in fig. 55, is, when fastened on the 
 shafts, engaged by two bolts A B, and C, which pass through 
 the box at right angles to each other, and one of them 
 through each of the shafts. As it is almost impracticable to 
 form the axes of two shafts with such accuracy that they shall 
 present one truly straight line ; and as the shafts will, though 
 made never so accurate, wear unequally, both these couplings 
 have been found to be somewhat disadvantageous in mill- 
 work. The square coupling with one bearing, is decidedly 
 superior to either of the above-mentioned, as it possesses, to 
 a certain degree, the property of being flexible in all directions. 
 In conveying motion through a great length of shafts, where 
 there is but little lateral pressure, it can be used to great advan- 
 tage ; but where there is much lateral pressure the sockets are 
 found to wear away and get loose, which occasions a hobbling 
 and inaccurate motion. A longitudinal section of this coupling 
 is represented in fig. 56, where A is the square of one shaft, 
 B the square of the other, C C the coupling box, and D D 
 two pins, one of which passes through each square of the 
 shafts, in order to support the square B in a line with the 
 square A. Sometimes the square B is held in a line with the 
 square A by means of a round projection F, from the centri 
 
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 n.:> . 
 
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 rn 
 
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 Fiq.oH. 
 
 W k H 
 
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 J'/q 
 
 
 
 
 Fitj.S4. 
 
 Fuf. 69 . 
 
 
 r 
 
 r 
 
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 Fig. 66 . 
 
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 'i/4 
 
AND MACHINIST. 31 
 
 of the square A, entering into a round hole in the centre of 
 the square B. 
 
 Clutches or glands may be used with much advantage as 
 a coupling for double bearings. Fig. 5J represents a coup- 
 ling of this kind ; it consists of two crosses, A A and B B, 
 
 < one fixed to each shaft ; B B has its ends bended forward, 
 and lays hold of A A, which turns that shaft round.^ 
 
 In boring-mills two kinds of clutches are used. The one 
 for the smaller kinds of work is represented in fig. 58. 
 A B is a round plate of cast iron fixed firmly on the shaft C ; 
 D E a lever fixed to the shaft H by the bolt F, and capable 
 of being moved in the direction of the plate A B, so that it 
 can lay hold of the projections G G GG, which will admit the 
 boring shaft H to be thrown in and out of geer at pleasure. 
 
 The second kind of boring-mill clutch, or the one that is 
 used to bore the largest cylinders, is represented in fig. 59. 
 The only difference between this clutch and the one just 
 described, consists in having the lever D E to turn on a bolt 
 at F in a cast iron plate IKE, instead of hanging from the 
 shaft H. Three spare sets of ears, which are cast on the 
 plate, to be used in case of those in action breaking, support 
 the lever near the point of pressure, and take the stress 
 entirely off the bolt F. 
 
 When an engine is started, it frequently happens that the 
 crank is on the wrong side of the axis of the fly-wheel, so that 
 both that and the shaft make one or two, and, if the attend- 
 ant is negligent, several, revolutions in the wrong direction. 
 To prevent the mischief that would accrue from such an oc- 
 currence, a coupling, as is represented in fig. 60, is intro- 
 duced. A and B are two vertical shafts, maintained in the 
 same line by a small circular pin, which passes from the shaft 
 B into a cavity on the shaft A, which cavity is large enough 
 to admit the pin to lay in it without communicating motion 
 to the shaft A. The shaft B, which is connected with the 
 moving power, has a coupling piece with prominences or 
 teeth, perpendicular on the one side, and inclined on the 
 other, fixed on its upper end. The coupling or catch box 
 C, which is capable, of sliding freely up and down the square 
 part of the shaft A, has a correspondent set of teeth ; by 
 which it is evident, that when the shaft B turns the right 
 way, the perpendicular sides of the teeth of the respective 
 coupling pieces will act together, and carry round the upper 
 
 * For a method of constructing glands we must refer our readers to 
 Buchanan’s Essays on Mill-work. 
 
32 
 
 THE OPERATIVE MECHANIC 
 
 shaft A ; but when B turns in a contrary direction^ the in- 
 clined sides of the teeth of the catch-box will slide over the 
 inclined sides of the teeth of the piece on the shaft B. and 
 cause the catch-box C to move up and down without com- 
 municating motion to the shaft A. 
 
 o 
 
 Fig. 61 represents the coupling link used by Messrs. Boul- 
 ton and Watt in their portable steam-engines. A, a strong 
 iron pin^ projecting from one of the arms of the fly-wheel B ; 
 D a crank connected with the shaft C ; and E a link to couple 
 the pin A and the crank D together, so that motion may be 
 communicated to the shaft C. 
 
 Hook’s universal joints are sometimes used to communi- 
 cate motion obliquely instead of conical wheels. Fig. 62 
 represents a single universal joint, which may be employed 
 where the angle does not exceed forty degrees, and when the 
 shafts are to move with equal velocity. The shafts A and B, 
 being both connected with a cross, move on the rounds at 
 the points C E and D F, and thus, if the shaft A is turned 
 round, the shaft B will likewise turn with a similar motion in 
 its respective position. 
 
 The double universal joint, fig. 63, conveys motion in 
 different directions when the angle is between 50 and 90 
 degrees. It is at liberty to move on the points G, H, I, K, 
 connected with the shaft B ; also on the points L, M, N, I, 
 connected with the shaft A : thus the two shafts are so con- 
 nected, that the one cannot turn without causing the other to 
 turn likewise. These joints may be constructed by a cross 
 of iron, or with four pins fastened at right angles upon the 
 circumference of a hoop or of a solid ball ; they are of great 
 use in cotton mills, where the tumbling shafts are continued 
 to a great distance from the moving power j for by applying 
 a universal joint, the shafts maybe cut into convenient lengths, 
 and so be enabled to overcome a greater resistance. 
 
 OF DISENGAGING AND REENGAGING MACHINERY. 
 
 A KNOWLEDGE of the best methods of disengaging and re- 
 engaging machinery, or, as the workmen call it, throwing in 
 and out of geer, is found to be highly necessary in most manu» 
 factories ; and yet it frequently happens that the workmen are 
 either very ignorant of, or very inattentive to, this important 
 subject. 
 
 Matter possesses a certain property termed inertia^ which 
 has a tendency to maintain it in the state in which it actually 
 is; that is to say, if a body is set in motion, this property has 
 a tendency to maintain it for ever in that state, and certainly 
 
AND MACHINIST. 
 
 33 
 
 would, were it not gradually overcome by friction, or suddenly 
 stopped by some stronger power ; the same may be said of a 
 body in a state of rest, as this property would ever maintain 
 it in that state, were not some stronger force applied to set it 
 in motion. Such being the case, it frequently occurs, when 
 powerful machinery is moving with some velocity, and another 
 part, which is out of geer, is suddenly connected with it, or 
 thrown in geer, that the shock proceeding from inertia 
 snaps the teeth of the wheels, or causes destruction to some 
 other part of the machinery. To obviate this as much as 
 possible, such means should be resorted to, as have been 
 found in practice to answer best. The risk of breaking 
 the teeth may be considerably lessened by first setting 
 the wheel, that is to be thrown in geer, in motion by the 
 hand. 
 
 The methods that have been adopted for throwing ma- 
 chinery in and out of geer are various ; some of the principal 
 of which we shall now proceed to notice. 
 
 Fig. 64 represents the sliding pulley. P a pulley, having 
 a hollow cylindrical bush made so that it can revolve easily 
 upon the axle and slide backward and forward upon it ; B a 
 part of the bush projecting on one side of the pulley, having 
 a groove sufficiently large to admit the lever L to lay in it 
 without impeding its motion ; C G a cross or gland fixed 
 firm to the axle; and I, one or more teeth, projecting from 
 the pulley on the side opposite to the bush. When the axle 
 AD is required to be put in motion, the lever L must be 
 moved towards the cross or gland C G, so that the teeth 
 upon the pulley may catch hold of and carry it round with it. 
 
 The fast and loose pulley is represented in fig. 65. B is a 
 pulley firmly fixed on the axle A, and C a pulley with a bush, 
 so that it can revolve upon the axle A without communicating 
 motion to it. This contrivance is remarkable for its beauti- 
 ful simplicity, as the axle A can be thrown in and out of 
 geer at pleasure, without the least shock, by simply passing 
 a strap from the one pulley to the other. 
 
 The bayonet, in its construction, somewhat resembles the 
 sliding pulley. It is shown in fig. 66. A is a pulley or 
 binder, connected with the moving machinery by means of a 
 strap, and revolving upon the horizontal shaft B C, which is 
 out of geer ; D E is a pulley or wheel, made of either metal 
 or wood, fixed firmly to the horizontal shaft, and having two 
 holes to allow the legs of the bayonet to pass through ; F G 
 is the bayonet, having a bush, and capable of being moved 
 
 D 
 
34 
 
 THE OPERATIVE MECHANIC 
 
 backward and forward upon the horizontal shaft by pushing 
 the handle H H 5 so that when the shaft B C is required 
 to be put in motion, the attendant has only to push the 
 bayonet into the pulley D E, which will immediately carry it 
 round. 
 
 Fig. 67 represents one of the simplest ways of disengaging 
 and reengaging wheels. A B, the bridge of the wheel, j| 
 No. 1, acts as a lever, having its fulcrum at A ; the other 
 end of the bridge B is capable of being lifted by the key » 
 K K. When the wheel. No. 2, is required to be thrown out 
 of geer, the key K K is pressed downwards, and the end of 
 the bridge B rests upon the extreme end of the key, as shown 
 by the dotted lines. 
 
 The tightening roller is represented in fig. 68 . A and B 
 are two pullies, the one to receive, and the other to transmit, 1 
 motion, by means of the strap C : D is the tightening roller, 1 
 fastened to a movable arm E, and connected with a lever 
 G F. When the moving pulley (suppose A) is required to ' 
 give motion to the other pulley B, the lever G F must be 
 pushed downwards, which will tighten the strap by placing 
 the tightening roller in the position represented by the dotted ^ 
 lines, and cause the pulley A to carry the pulley B round i 
 with it. - 
 
 The friction clutch, represented in fig. 69, is used to dis- 
 engage and reengage machinery, when the velocity of the 
 moving parts is very great. A is a pulley, having a bush, 
 and revolving freely on the shaft S S : B is another pulley, 
 having a similar bush, and also capable of revolving on the 
 shaft : C C is a dish-spring, secured in its place by the pin 
 p p, and forcing the pulley B against the collar D, which is 
 fixed permanently to the shaft. When motion is required 
 to be communicated to the shaft S S, the pulley A is moved 
 towards the pulley B, and the teeth projecting from the side 
 of the pulley A, clasps those of the pulley B, and carries it 
 round with it ; and the friction of the pulley B against the 
 collar D, gradually overcomes the inertia, and carries the 
 shaft and connecting machinery also round. 
 
 The friction clutch, represented in fig. 70, is a very excellent 
 contrivance, as it prevents all those injurious shocks which 
 the machinery is apt to receive upon being thrown into geer. 
 
 C C is a cross fixed firm on the moving shaft A ; and 
 E is a pulley or drum fixed firm on the shaft to be moved, B. 
 When the shaft B is required to be moved, the clutch or 
 bayonet K is made to pass through the arms of the cross C C, 
 
AND MACHINIST. 
 
 S5 
 
 and clasp the screw-hoop 1 1, which is by that means carried 
 round with the shaft A, and the friction caused by the screw- 
 hoop 1 1, turning upon the drum or pulley E, causes the drum 
 and the shaft B, to which it is attached, to turn likeadse. 
 
 The friction cone is very similar in its effects to the fric- 
 tion clutch. On the moving shaft A, fig. 71? is fixed a cone 
 C ; and on the shaft B is another cone D, made to fit in the 
 cone C. The cone D is movable on a square part of the 
 shaft B, and may, by a lever, be moved in and out of geer. 
 When the cone I) is moved forward, the cone C receives 
 motion by its internal surface. 
 
 In fig. 72 is represented the self-disengaging coupling. 
 Two shafts, A and B, have each of them a cast iron wheel, with 
 four oblique wrought iron teeth ; but the wheel on the shaft 
 B is movable, on A it is fixed. When the coupling is en- 
 gaged, the teeth of 'the wheel C lay hold of the teeth of the 
 wheel D, and carry it, and the shaft A, round with the shaft 
 B. E F G is a bent lever, having its fidcrum at F, which, 
 during the ordinary stress on B, keeps forward the bayonet C, 
 by the weight of the part F G ; but when a more than usual 
 stress comes on the shaft B, the pressure on the oblique 
 teeth forces the bayonet back, and disengages the coupling, 
 and the lever is held by a catch until the coupling is re- 
 engaged by the hand of the workman. 
 
 ON EQUALIZING THE MOTION OF MACHINERY. 
 
 The regulation of the velocity of a mill is a matter of very 
 great importance to preserve an uniformity of motion, either 
 when the force of the first mover is fluctuating, or when the 
 resistance or work of the mill varies in its degree : either or both 
 of these causes will occasion the mill to accelerate or diminish 
 its velocity; and in many instances it will have a very injurious 
 effect upon the operations of the mill. Thus, in a mill for 
 spinning cotton, wool, flax, &c., driven by a water-wheel, are 
 a multiplicity of movements, many of which are occasionally 
 disengaged, in different parts of the mill, for various purposes. 
 This tends to diminish the resistance to the first mover, and 
 the whole mill accelerates. Or, on the other hand, the head 
 of water, which drives the wheel, may be liable to rise and 
 fall suddenly, from many causes, which great and rapid rivers 
 are subject to, and cause similar irregularities in the speed of 
 the wheel. For such cases judicious mechanics have adopted 
 contrivances, or regulators, which counteract all these causes 
 of irregularity ; and a large mill, so regulated, will move like 
 a clock, with regard to its regularity of velocity. These 
 
 D 2 
 
36 
 
 THE OPERATIVE MECHANIC 
 
 regulators are usually called called goveriiors, and are made 
 on different principles. Those most generally used are called 
 flying-balls^ operating by the centrifugal force of two heavy 
 balls, which are connected and revolve with a vertical axis. 
 Fig. 189^ steam-engine, is the simplest form of this ingenious 
 apparatus : A A is the vertical axis, which is constantly revolv- 
 ing by the machinery; at a a two arms or pendulums, ab, a b, 
 are jointed, and carry at their extremities a heavy metal ball 
 each, as b, b; from the pendulum two chains or iron rods, 
 d r/, proceed, and suspend a collar c, which slides freely up 
 and down the axis, and has a groove formed all round it, in 
 which the end of a forked lever, D, is received; and thus the 
 rising and the falling of the collar e, produces a corresponding 
 motion of the end of the lever D; but the collar is always at 
 liberty to turn round with the axis freely within the fork, 
 at the extremity of the lever. The operation of the governor 
 is this : when the vertical axis is put in motion, the centri- 
 fugal force of the balls Z», Z>, causes them to recede from the 
 centre; and as this is done both together, they cause the 
 collar c, and the end of the lever, to rise up ; the balls fly out 
 to a certain height, and there they continue as long as the 
 axis preserves the same velocity ; as it is the property of a 
 pendulous ball, like Z», to make a greater effort to return to 
 the perpendicular, in proportion as it is removed farther from 
 it, in consequence of the suspending rod being more inclined, 
 and bearing less of its weight. The weight of the balls to 
 return to the axis may be considered as a constantly increasing 
 quantity; while the quantity of the centrifugal force, causing 
 them to recede from the axis, depends exactly upon the 
 velocity given them. But this velocity increases as they open 
 out, independently of any increased velocity of the axis, in 
 consequence of their describing a larger circle. The com- 
 bination of these oppositely acting forces causes the governor 
 to be a most sensible and delicate regulator. Thus : suppose 
 the balls hanging perpendicular put the axis in motion with 
 a certain velocity, the centrifugal force will cause the balls 
 to fly out; and this increasing their velocity, (by putting 
 them farther from the centre, and causing them to revolve in 
 a larger circle,) gives them a greater centrifugal force, which 
 would carry them still farther from the centre, but for the 
 counteracting force, viz, the weight of the balls tending to 
 return. This is, as before stated, an increasing quantity, 
 and consequently these opposite forces come to a point where 
 they balance each other; that is, the balls fly out till their 
 weight to return balances the centrifugal force. But if the 
 
PI. 6. 
 
 From 70 to 78 . 
 
 71 
 
 ^aU k .^toMiy si-se^ Strand. 
 
AND MACHINIST. 
 
 37 
 
 slightest alteration takes place in the velocity of the axis, 
 the equilibrium is destroyed by the increase or diminution cf 
 the centrifugal force, and the balls alter their distance from 
 the centre accordingly, and, by elevating or depressing the 
 end of the lever, operate upon some part of the mill to rectify 
 the cause of the irregularity. In a steam-engine, the lever 
 acts upon a vane or door situated in the passage of the steam 
 from the boiler to the cylinder ; and if the mill loses in velo- 
 city, from an increase of resistance, the balls fall together a 
 little, and the consequent fall of the lever opens the door or 
 throttle- valve a little wider, and gives a stronger supply of 
 steam to restore the mill to its original velocity. On the 
 other hand, if the mill accelerates, the balls open out and 
 then close the vane, so as to moderate the supply of steam. 
 
 A water-wheel is not so easily regulated by the governor, 
 because the shuttle of a large wheel requires a much greater 
 force to raise or lower it, when the water is pressing against 
 it, than the lever O, can at any time possess^ it therefore 
 becomes requisite to introduce some additional machinery, 
 which has sufficient power to move the shuttle, and this is 
 thrown in or out of action by the flying balls. The simplest 
 contrivance, and that which we believe was the regulator first 
 used for a water-wheel, was erected at a cotton-mill at 
 Belper, in Derbyshire, belonging to Mr. Strutt. A square 
 well, or large cistern, was situated close by the water-wheel ; 
 it had a pipe leading from the mill-dam into it, to admit 
 water; and another pipe from it to the mill-tail, to take the 
 water away: both were closed at pleasure by cocks or sluices. 
 Within the well was a large floating chest, very nearly filling 
 up the space : it of course rose and fell with the water in the 
 cistern, and liad a communication by rack and wheel-work 
 with the machinery for drawing the shuttle, so that the rise 
 and fall of the floating chest elevated and depressed the 
 shuttle of the wheel. The lever of the governor was con- 
 nected with the cocks in the two pipes in such a manner, 
 that when the mill was going at its intended velocity, both of 
 the cocks were shut; but if the water-wheel went too slowly, 
 the falling of the bails and descent of their lever D, opened 
 the cock in the pipe of supply, and, by letting water into the 
 well, raised the float, and, with it, the shuttle, to let more 
 water upon the wheel, till it acquired such a velocity that the 
 balls began to open out again, and thus shut the cock : on 
 the other hand, if the mill went too fast, the balls opened the 
 pipe of exit from the well, and then the sinking of the float 
 closed the shuttle till the true velocity was restored. 
 
38 
 
 THK OPERATIVE MECHANIC 
 
 Since this first application of the regulator to the water- 
 wheel, the manner of its operation has been greatly varied; 
 and as the same mechanism is applicable to any kind of 
 mill-work, we shall give a slight sketch of it. Suppose A, 
 fig. 74, an axis, receiving its motion from the mill by wheel- 
 work; it is provided with a pair of governors, ab, a b, con- 
 structed like those before described ; and at the lower part of 
 the spindle is a bevelled wheel, R, turning two others, B and 
 
 C, situated upon one spindle, D, which goes away, and 
 communicates motion to the racks of the shuttle; the wheels, 
 B and C, are neither of them fixed to the spindle D, but both 
 slip round freely upon it, turning in contrary directions, as 
 they receive motion from the opposite sides of the wheel R. 
 A locking clutch, c?, is fitted upon the spindle between these 
 two wheels, B, C, and can, by moving it one way or the 
 other, be made to lock either one of the wheels to the spindle 
 
 D, at the same time that it leaves the other disengaged. 
 The locking-box is moved by means of a lever, shown in 
 fig. 73, the arm m having a fork to embrace a groove in the 
 box ; the lever is fixed on a vertical axis w, which has at the 
 upper end two other levers, o, p; these lay one at each side 
 of the vertical axis A, but at different heights, as is evident 
 from the figure. The collar c, which is raised up when the 
 balls fly out, is fitted upon a square part of the spindle A, 
 and is formed like a snail or camm, which will act upon either 
 of the levers, o or according to the height at which it 
 hangs upon its spindle. Now when the mill is going with 
 its true velocity, this camm e is at such a height that it is 
 beneath one lever, o, and above the other, p, so as to inter- 
 fere with neither; consequently the locking-box, c?, remains 
 detached : but on any alteration in the velocity of the mill 
 and the axis A, the balls open or shut, as before explained, 
 and the camm, c, either rises or falls, and then it presses against 
 one of the levers, o or jo, and by pushing it away from the 
 axis, it moves the lever m, and the locking-box up to one 
 of the wheels, B or C, which it locks to the axis D, and turns 
 it round in the direction of that wheeFs motion, by which it 
 either raises or depresses the v/ater-wheeFs shuttle, as is 
 required. This apparatus may, it is plain, be applied to any 
 other kind of mill-work. 
 
 Governors or flying-balls are very frequently used in the 
 wind-mills employed for grinding flour : the variable force of 
 this first mover renders some such regulator necessary, to 
 increase the resistance, by allowing a greater feed of corn, 
 when the mill moves too quickly, and thus in some degree 
 
AND MACHINIST. 
 
 39 
 
 counteracting the irregularity. If the mill moves too slowly, 
 the balls tend to diminish the feed, and at the same time 
 they raise the upper stone, to set them at a greater distance 
 asunder, that they may require less power to drive them, and 
 consequently suffer the mill, as nearly as it can, to retain its 
 full velocity, though the motive force is greatly diminished. 
 This application of the governor was, we believe, first made 
 by the ingenious captain Hooper of Margate, who invented 
 the horizontal wind-mill. It is a very great advantage, and 
 no wind-mill should be without them. Many wind-mills are 
 provided with flying-balls, which, by very ingenious me^ 
 chanism, clothe and unclothe the sails just in proportion to 
 the strength of the wind. 
 
 In many mills it is of consequence to be able to detect 
 small variations in the velocity, and to ascertain the quantity 
 of them; for the governor only corrects the irregularities, 
 without showing any scale of them. In cases where this is 
 required, it may be done by a very ingenious instrument, 
 invented by Mr. Bryan Donkin, of Fort-place, Bermondsey, 
 He received a gold medal from the Society of Arts, Manu- 
 factures, and Commerce, in 1810, for this instrument, which 
 he calls a tachometer. 
 
 A front view of Mr, Donkin^ s tachometer^ or instru- 
 ment for indicating the velocity of Machinery^ is represented 
 in fig. 70 , and a side view in fig. 77* X Y Z, fig. 70, is the 
 vertical section of a wooden cup, made of box, which is 
 drawn in elevation at X, fig. 77 * The whiter parts of the 
 section, in fig. 76, represent what is solid, and the dark parts 
 what is hollow. This cup is filled with mercury up to the 
 level L L, fig. 76. Into the mercury is immersed the lower 
 part of the upright glass tube A B, which is filled with 
 coloured spirits of wine, and open at both ends, so that some 
 of the mercury in the cup enters at the lower orifice, and 
 when every thing is at rest, supports a long, column of spirits, 
 as represented in the figure. The bottom of the cup is 
 fastened by a screw to a short vertical spindle D, so that when 
 the spindle is whirled round, the cup (whose figure is a solid 
 of revolution) revolves at the same time round its axis, which 
 coincides with that of the spindle. 
 
 In consequence of this rotation, the mercury in the cup 
 acquires a centrifugal force, by which its particles are thrown 
 outwards, and that with the greater intensity, according as 
 they are more distant from the axis, and according as the 
 angular velocity is greater. Hence, on account of its fluidity, 
 the mercury rises higher and higher as it recedes from the 
 
40 
 
 THE OPERATIVE MECHANIC 
 
 axis, and consequently sinks in the middle of the cup ; this 
 elevation at the sides and consequent depression in the 
 middle increasing always with the velocity of rotation. Now 
 the mercury in the tube, though it does not revolve with the 
 cup, cannot continue higher than the mercury immediately 
 surrounding it, nor indeed so high, on account of the super- 
 incumbent column of spirits. Thus the mercury in the tube 
 will sink, and consequently the spirits also ; but as that part 
 of the tul3e which is within the cup is much wider than the 
 part above it, the depression of the spirits will be much 
 greater than that of the mercury, being in the same propor- 
 tion in which the square of the larger diameter exceeds the 
 square of the smaller. 
 
 Let us now suppose, that by means of a cord passing round 
 a small pulley F, and the wheel G or H, or in any other 
 convenient way, the spindle D is connected with the machine 
 whose velocity is to be ascertained. In forming this con- 
 nection, we must be careful to arrange matters so, that when 
 the machine is moving at its quickest rate, the angular 
 velocity of the cup shall not be so great as to depress the 
 spirits below C into the wider part of the tube. We are 
 also, as in the figure, to have a scale of inches and tenths 
 applied to A C, the upper and narrower part of the tube, the 
 numeration being carried downwards from zero, which is to 
 be placed at the point to which the column of spirits rises 
 when the cup is at rest. 
 
 Then the instrument will be adjusted, if we mark on the 
 scale the point to which the column of spirits is depressed, 
 when the machine is moving with the velocity required. 
 But, as in many cases, and particularly in steam-engines, 
 there is a continued oscillation of velocity, in those cases we 
 have to note the two points between which the column 
 oscillates during the most advantageous movement of the 
 machine. 
 
 Here it is proper to observe, that the height of the column 
 of spirits will vary with the temperature, when other cir- 
 cumstances are the same. On this account the scale ought 
 to be movable, so that, by slipping it upwards or downwards, 
 the zero may be placed at the point to which the column 
 reaches when the cup is at rest ; and thus the instrument 
 may be adjusted to the particular temperature with the utmost 
 facility, and with sufficient precision. The essential parts of 
 the tachometer have now been mentioned, as well as the 
 method of adjustment 5 but certain circumstances remain tQ 
 be staled, 
 
AND MACHINIST. 
 
 41 
 
 The form of the cup is adapted to render a smaller quantity 
 of mercury sufficient, than what must have been employed 
 either with a cylindrical or hemispherical vessel. In every 
 case two precautions are necessary to be observed : — first, 
 that when the cup is revolving with its greatest velocity, the 
 mercury in the middle shall not sink so low as to allow any 
 of the spirits in the tube to escape from the lower orifice, 
 and that the mercury, when most distant from the axis, shall 
 not be thrown out of the cup. Secondly, that when the cup 
 is at rest, the mercury shall rise so high above the lower end 
 of the tube, that it may support a column of spirits of the 
 proper length. 
 
 Now in order that the quantity of mercury, consistent 
 with these conditions, may be reduced to its minimum, it is 
 necessary — first, that if M M, fig. 7^, is the level of the 
 mercury at the axis, when the cup is revolving with tlie 
 greatest velocity, the upper part M M X Y of the cup should 
 be of such a form as to have the sides covered only with a 
 thin film of the fluid ; and, secondly, that for the purpose of 
 raising the small quantity of mercury to the level L L, which 
 may support a proper height of spirits when the cup is at 
 rest; the cavity of the cup should be in a great measure 
 occupied by the block K K, having a cylindrical perforation 
 in the middle of it for the immersion of the tube, and 
 leaving sufficient room within and around it for the mercury 
 to move freely both along the sides of the tube and of the 
 vessel. 
 
 The block K K is preserved in its proper position in the 
 cup or vessel X Y Z, by means of three narrow projecting 
 slips or ribs placed at equal distances round it, and is kept 
 from rising or floating upon the mercury by two or three 
 small iron or steel pins inserted into the under side of the 
 cover, near the aperture through which the tube passes. 
 
 It would be extremely difficult, however, nor is it by any 
 means important, to give to the cup the exact form which 
 would reduce the quantity of mercury to its minimum ; but 
 we shall have a sufficient approximation, which may be exe- 
 cuted with great precision, if the part of the cup above M M 
 is made a parabolic nonoid, the vertex of the generating para- 
 bola being at that point of the axis to which the mercury 
 sinks at its lowest depression, and the dimensions of the 
 parabola being determined in the following manner. Let 
 V G, fig. 78, represent the axis of the cup, and V the point 
 to which Ihe mercury sinks at its lowest depression ; at any 
 point G above V, draw G H perpendicular to V G ; let n be 
 
42 
 
 THE OPERATIVE MECHANIC 
 
 the number of revolutions which the cup is to perform in 
 
 at its quickest motion ; let v be the number of inches 
 which a body would describe uniformly in 1", with the velo- 
 city acquired in falling from rest, through a height = to 
 
 V 
 
 G V, and make G H = . Then, the parabola to be 
 
 6 n 
 
 determined is that which has v for its vertex, V G for its 
 axis, and G H for its ordinate at G. The cup has a lid to 
 prevent the mercury from being thrown out of it, an event 
 which would take place with a very moderate velocity of 
 rotation, unless the sides were raised to an inconvenient 
 height ; but the lid, by obstructing the elevation at the sides 
 of the cup, will diminish the depression in the middle, and 
 consequently the depression of spirits in the tube ; on this 
 account a cavity is formed in the block immediately above 
 the level L/L, where the mercury stands when the cup is at 
 rest ; and thus a receptacle is given to the fluid, which would 
 otherwise disturb the centrifugal force and impair the sensi- 
 bility of the instrument. 
 
 It will ])e observed, that the lower orifice of the tube is 
 turned upwards. By this means, after the tube has been 
 filled with spirits by suction, and its upper orifice stopped 
 with the finger, it may easily be conveyed to the cup and 
 immersed in the quicksilver without any danger of the spirits 
 escaping ; a circumstance which otherwise it would be ex- 
 tremely difficult to prevent, since no part of the tube can be 
 made capillary, consistently with that free passage to the 
 fluids, which is essentially necessary to the operation of the 
 instrument. 
 
 We have next to attend to the method of putting the 
 tachometer in motion whenever we wish to examine the velo- 
 city of the machine. The pulley F, which is continually 
 w’hirling during the motion of the machine, has no connec- 
 tion whatever with the cup, so long as the lever Q R is left 
 to itself. But when this lever is raised, the hollow cone T, 
 which is attached to the pulley and whirls along with it, is 
 also raised, and embracing a solid cone on the spindle of the 
 cup, communicates the rotation by friction. When our ob- 
 servation is made, we have only to allow the lever to drop by 
 its own weight, and the two cones will be disengaged, and 
 the cup remain at rest. 
 
 The lever Q R is connected by a vertical rod to another 
 lever S, having, at the extremity S a valve, which, when the 
 lever Q R is raised, and the tachometer is in motion, is 
 lifted up from the top of the tube, so as to admit the external 
 
AND MACHINIST. 
 
 43 
 
 air upon the depression of the spirits ; on the other hand, 
 when the lever Q R falls, and the cup is at rest, the valve 
 at S closes the tube, and prevents the spirits from being 
 wasted by evaporation. 
 
 It is lastly to be remarked, that both the sensibility and 
 the range of the instrument may be infinitely increased ; for, 
 on tlie one hand, by enlarging the proportion between the 
 diameters of the wide and narrow parts of the tube, we 
 enlarge in a much higher proportion the extent of scale cor- 
 responding to any given variation of velocity ; and on the 
 other hand, by deepening the cup so as to admit when it is 
 at rest a greater height of mercury above the lower end of 
 the tube, we lengthen the column of spirits which the mer- 
 cury can support, and consequently enlarge the velocity, 
 which, with any given sensibility of the instrument, is re- 
 quisite to depress the spirits to the bottom of the scale. 
 Hence the tachometer is capable of being employed in very 
 delicate philosophical experiments, more especially as a 
 scale might be applied to it, indicating equal increments of 
 velocity. But in the present account it is merely intended 
 to state how it may be adapted to detect in machinery every 
 deviation from the most advantageous movement. 
 
 General Observations . — In setting out the geering of a 
 mill, it should be the object of the engineer to place the 
 heaviest machinery nearest the moving power, as, in trans- 
 mitting motion to a great distance, not only the weight of 
 shafting is to be taken into consideration, but the friction 
 which exists in all the different bearings, and which is 
 greatly increased by a small obstacle placed beyond those 
 bearings. 
 
 Care likewise should be taken to make as few bearings as 
 possible, still keeping in view that the shafts must not be 
 allowed to swag. Rules might be given for the distances of 
 the bearings of the shafting, if the shafting had only to move 
 itself, but having to carry various sized pullies, both their 
 weight and the weight of the machinery they turn must be 
 taken into consideration, which compel us to forego the at- 
 tempt 3 it is, however, necessary to state, that it is better to 
 have a bearing too many than to allow a shaft to bend, as it 
 cannot then run true in its steps or journals. 
 
 In forming couplings, great care should be taken to make 
 them fit, so that the coupled shaft may move as though of 
 the same piece with the driving shaft : nor can simplicity be 
 too strongly recommended, that the coupled shaft may, in 
 .case of an accident, be instantaneously disengaged, for the 
 
44 
 
 THE OPERATIVE MECHANIC 
 
 loss of time arising from any accident is of serious im- 
 portance to the manufacturer. Couplings should be placed 
 near the bearings, as there is there the least swag, and the 
 shaft is of course the weakest at the couplings. The same 
 observation is applicable to the disposing of wheels and 
 pullies. 
 
 Pullies have been sometimes formed in two halves for 
 putting upon the shaft without taking the shaft down, but 
 their adoption is by no means general, as there is some 
 difficulty in fixing them true whilst the shaft is in its place. 
 
 Straps to drive geering should be avoided whenever wheels 
 can be substituted, as they are very liable to stretch and 
 break, and do not transmit regular motion. In fixing the 
 wheels and pullies upon a shaft, which is mostly done b)^ 
 driving wedges in the bush of the wheel or pulley, called 
 staking them on, great pains should be taken to have them 
 true, which can only be done by driving the wedges regu- 
 larly on each side to the same degree of tightness. It most 
 generally happens when one wedge is over-driven, the work- 
 men, rather than take the trouble to alter it, will let it re- 
 main ; but this is of more importance than is generally 
 imagined, for if a wheel is not true, it cannot work in the 
 pitch line, all round, and where it is out it will shake, or have, 
 what is called, hack-lash, which, happening always in the 
 same place, will wear the ".vhecls irregularly. If a pulley is 
 not true, it will communicate irregular motion by its strap, 
 and likewise cause an irregular stress upon the shaft on which 
 it works, much to the detriment of the bearing. 
 
 Chains have been beneficially introduced as substitutes 
 for straps in driving heavy geer. 
 
 Shafts should be circular, as they are less likely to catch 
 any thing, and have a much neater appearance. The same 
 may be said of couplings. The wheels of the geering 
 should be always enclosed in a casing of wood, called boxing 
 o//, to prevent any thing failing in between them, or accidents 
 occurring to the people who maybe working near them. The 
 wheels should be furnished with brushes resting upon their 
 faces, to distribute the'grease equally and to keep it between 
 the teeth : and on starting a new pair of wheels, a little 
 emery may be put on with the gi*ease, to bring them to a 
 smooth face. 
 
 The following general observations on the construction 
 of Machines, and on the regulating of their motions, appear 
 to be highly worthy of the Mill-wrighCs attention ; we 
 have, therefore, extracted them from jJr. Robison’s article 
 
AND MACHINIST. 45 
 
 on Machinery^ inserted in the Supplement to the Encydo 
 pcjcdia Britannica. 
 
 When heavy stampers are to be raised, in order to 
 drop on the matters to be pounded, the wipers by which 
 they are lifted should be made of such a form, that the 
 stamper may be used by a uniform pressure, or with a 
 motion almost perfectly uniform. If this is not attended 
 to, and the wiper is only a pin sticking out from the axis, 
 the stamper is forced into motion at once. This occasions 
 violent jolts to the machines, and great strains on its moving 
 parts and their points of support ; whereas, when they are 
 gradually lifted, the inequality of desultory motion is never 
 felt at the impelled point of the machine. We have seen 
 pistons moved by means of a double rack on the piston 
 rod. A half wheel takes hold of one rack, and raises it to 
 the required height. The moment the half wdieel has quit- 
 ted that side of the rack, it lays hold of the other side, and 
 forces the piston down again. This is proposed as a great 
 improvement ; connecting the unequable motion of the 
 piston moved in the common w^ay by a crank. But it is far 
 inferior to the crank motion. It occasions such abrupt 
 changes of motion, that the machine is shaken by jolts. 
 Indeed, if the movement were actually executed, the machine 
 would be shaken to pieces, if the parts did not give w^ay by 
 bending and yielding. Accordingly, we have ahvays observed 
 that this motion soon failed, and was changed for one that 
 was more smooth. A judicious engineer will avoid all such 
 sudden changes of motion, especially in any ponderous part 
 of a machine. 
 
 When several stampers, pistons, or other reciprocal 
 movers, are to be raised and depressed, common sense teaches 
 us to distribute their times of action in a uniform manner, so 
 that the machine may always be equally loaded with work. 
 When tins is done, and the observations in the preceding 
 paragraph attended to, the machine may be made to move 
 almost as smoothly as if there ^vere no reciprocations in it. 
 Nothing shows the ingenuity more than the artful yet simple 
 and effectual contrivances for obviating those difficulties 
 that unavoidably arise from the very nature of the w^ork 
 that must be performed by the machine, and of the power 
 employed. 
 
 There is also great room for ingenuity and good choice 
 in the management of the moving power, when it is such as 
 cannot immediately produce the kind of motion required for 
 effecting the purpose. We mentioned the conversion of the 
 
46 
 
 THE OPERATIVE MECHANIC 
 
 continued rotation of an axis into the reciprocating motion 
 of a piston^ and the improvement which was thought to have 
 been made on the common and obvious contrivance of a 
 crank, by substituting a double rack on the piston-rod, and 
 the inconvenience arising from the jolts occasioned by this 
 change. We have seen a great forge, where the engineer, 
 in order to avoid the same inconvenience arising from the 
 abrupt motion given to the great sledge hammer of seven 
 hundred weight, resisting with a five-fold momentum, formed 
 the wipers into spirals, which communicated motion to the 
 hammer almost without any jolt whatever; but the result 
 was, that the hammer rose no higher than it had been raised 
 in contact with the wiper, and then fell on the iron bloom 
 with very little effect. The cause of its inefficiency was not 
 guessed at; but it was removed, and wipers of the common form 
 were put in place of the spirals. In this operation, the rapid 
 motion of the hammer is absolutely, necessary. It is not 
 enough to lift it up ; it must be tossed up, so as to fly higher 
 than the wiper lifts it, and to strike with great force the strong 
 oaken spring which is placed in its way. It compresses this 
 spring, and is reflected by it with a considerable velocity, so 
 as to hit the iron as if it had fallen from a great height. 
 Had it been allowed to fly to that height, it would have 
 fallen upon the iron with somewhat more force, (because no 
 oaken spring is perfectly elastic,) but this would have re- 
 quired more than twice the time. 
 
 In employing a power which of necessity reciprocates, td 
 drive machinery which requires a continuous motion (as in 
 applying the steam-engine to a cotton or grist mill,) there 
 also occur great difficulties. The necessity of reciprocation 
 in the first mover wastes much power ; because the instru- 
 ment which communicates such an enormous force must be 
 extremely strong, and be well supported. The impelling 
 power is wasted in imparting, and afterwards destroying, a 
 vast quantity of motion in the working beam. The skilful 
 engineer will attend to this, and do his utmost to procure the 
 necessary strength of this first mover, without making it a 
 vast load of inert matter. He will also remark, that all the 
 strains on it, and on its supports, are changing their direc- 
 tions in every stroke. This requires particular attention to 
 the manner of supporting it. If we observe the steam- 
 engines which have been long erected, we see that they have 
 uniformly shaken the building to pieces. This has been 
 owing to the ignorance or inattention of the engineer in this 
 particular. They are much more judiciously erected now. 
 
AND MACHINIST. 
 
 47 
 
 experience having taught the most ignorant that no building 
 can withstand their desultory and opposite jolts, and that 
 the great movements must be supported by a frarne-w'ork 
 independent of the building of masonry wdiich contains it.* 
 
 The engineer will also remark, that when a single-stroke 
 steam-engine is made to turn a mill, all the communications 
 of motion change the direction of their pressure twice every 
 stroke. During the working stroke of the beam, one side of 
 the teeth of the intervening wheels is pressing the machinery 
 forward; but during the returning stroke, the machinery, 
 already in motion, is dragging the beam, and the wheels are 
 acting with the other side of the teeth. This occasions a 
 rattling at every change, and makes it proper to fashion 
 both sides of the teeth with the same care. 
 
 It will frequently conduce to the good performance of an 
 engine, to make the action of the resisting work unequable, 
 accommodated to the inequalities of the impelling powder. 
 This will produce a more uniform motion in machines in 
 which the momentum of inertia is inconsiderable. There 
 are some beautiful specimens of this kind of adjustment in 
 the mechanism of animal bodies. 
 
 It is very customary to add what is called a fly to ma- 
 chines. This is a heavy disk or hoop, or other mass of 
 matter balanced on its axis, and so connected with the 
 machinery as to turn briskly round wdth it. This may be 
 done with the view of rendering the motion of the whole 
 more regular, notwithstanding unavoidable inequalities of the 
 accelerating forces, or of the resistances occasioned by the 
 work. It becomes a regulator. Suppose the resistance ex- 
 tremely unequal, and the impelling power perfectly constant ; 
 as when a bucket-wheel is employed to one pump. When 
 the piston has ended its working stroke, and while it is going 
 down the barrel, the powder of the wheel being scarcelj^ op- 
 posed, it accelerates the wdiole machine, and the piston 
 arrives at the bottom of the barrel with a considerable velo- 
 city. But in the rising again, the wheel is opposed by the 
 column of water now pressing on the piston. This imme- 
 diately retards the wheel ; and when the piston has reached 
 
 * The gudgeons of a water-wheel should never rest on the wall of the 
 building. It shakes it; and if set up soon after the building has been 
 erected, it prevents the mortar from taking firm bond ; perhaps by shatter- 
 ing the calcareous crystals as they form. When the engineer is obliged to rest 
 the gudgeons in this way, they should be supported by a block of oak laid a 
 little hollow. This softens all tremors, like springs of a wheel carriage. 
 This practice would be very serviceable in many other parts of the con- 
 struction. 
 
48 
 
 THE OPERATIVE MECHANIC 
 
 tiie top of the barrel, all the acceleration is undone, and is to 
 begin again. The motion of such a machine is very hob- 
 bling : but the superplus of accelerating force at the begin- 
 ning of a returning stroke will not make such a change in 
 the motion of the machine if we connect the fly with it. For 
 the accelerating momentum is a determinate quantity. There- 
 fore, if the radius of the fly be great, this momentum will be 
 attained by communicating a small angular motion to the ma- 
 chine. 
 
 The momentum of the fly is as the square of its radius ; 
 therefore it resists acceleration in this proportion ; and 
 although the overplus of power generates the same momen- 
 tum of rotation in the whole machine as before, it makes but 
 a small addition to its velocity. If the diameter of the fly 
 be doubled, the augmentation of rotation wdll be reduced to 
 one-fourth. Thus, by giving rapid motion to a small quan- 
 tity of matter, the great acceleration during the returning 
 stroke of the piston is prevented. This acceleration conti- 
 nues, however, during the whole of the returning stroke, and 
 at the end of it the machine has acquired its greatest velo- 
 city. Now the working stroke begins, and the overplus of 
 power is at an end. The machine accelerates no more ; but 
 if the power is just in equilibrio with the resistance, it keeps 
 the velocity which it has acquired, and is still more accele- 
 rated during the next returning stroke. But now, at the be- 
 ginning of the subsequent working stroke, there is an over 
 plus of resistance, and a retardation begins, and continues 
 during the whole rise of the piston ; but it is inconsiderable 
 in comparison of what it would have been without the fly ; 
 for the fly, retaining its acquired momentum, drags forward 
 the rest of the machine, aiding the impelling power of the 
 wheel. It does this by all the commumcations taking into each 
 other in the opposite direction. The teeth of the interven- 
 ing wheels are heard to drop from their former contact on 
 one side, to a contact on the other. By considering this pro- 
 cess with attention, we easily perceive that, in a few strokes, 
 the overplus of power during the returning stroke comes to 
 be so adjusted to the deficiency during the working stroke, 
 that the accelerations and retardations exactly destroy each 
 other, and every succeeding stroke is made with the same 
 velocity, and an equal number of strokes is made in every 
 succeeding minute. Thus the machine acquires a general 
 uniformity with periodical inequalities. It is plain, that by suf- 
 ficiently enlarging either the diameter or the weight of the fly> 
 the irregularity of the motion may be rendered as small as we 
 
AND MACHINIST. 
 
 49 
 
 please. It is much better to enlarge the diameter. This 
 preserves the friction more moderate, and the pivot wears 
 less. For these reasons a fly is in general a considerable im- 
 provement in machinery, by equalizing many exertions that 
 are naturally very irregular. Thus, a man working at a com- 
 mon windlass exerts a very irregular pressure on the winch. 
 In one of his positions, in each turn he can exert a force of 
 near 70 lbs. without fatigue, but in another he cannot exert 
 above 25 lbs 3 nor must he be loaded with much above this 
 in general. But if a large fly be connected properly with 
 the windlass, he will act with equal ease and speed against 
 30 lbs. 
 
 This regulating power of the fly is without bounds, and 
 may be used to render uniform a motion produced by the 
 most desultory and irregular power. It is thus that the most 
 regular motion is given to mills that are driven by a single- 
 stroke steam-engine, wdiere, for two, or even three seconds, 
 there is no force pressing round the mill. The communica- 
 tion is made through a massive fly of very great diameter, 
 whirling with great rapidity. As soon as the impulse ceases, 
 the fly, continuing its motion, urges round the whole ma- 
 chinery with almost unabated speed. At this instant all the 
 teeth, and all the joints, between the fly and the first mover, 
 are heard to catch in the opposite direction. 
 
 If any permanent change should happen in the impelling 
 power, or in the resistance, the fly makes no obstacle to its 
 producing its full effect on the machine; and it will be observed 
 to accelerate or letard uniformly, till a new general speed is 
 acquired exactly corresponding with this new pouer and 
 resistance. 
 
 Many machines include, in their construction, movements 
 which are equivalent with this intentional regulator. A 
 flour mill, for example, cannot be better regulated than by 
 its mill-stone ; but in the Albion Mills, a heavy fly was added 
 with great propriety ; for if the mills had been regulated by 
 their mill-stones only, then, at every change of stroke in the 
 steam-engine, the whole train of communications between 
 the beam, which is the first mover, and the regulating mill- 
 stone, which is the very last mover, would take in the oppo-. 
 site direction. Although each drop in the teeth and joints 
 be but a trifle, the whole, added together, would make a con- 
 siderable jolt. This is avoided by a regulator immediately 
 adjoining the beam. This continually presses the working 
 machinery in one direction. So judiciously were the move- 
 ments of that noble machine contrived, and so nicely were 
 
 a 
 
5Q 
 
 THK OPERATIVE MECHANIC 
 
 they executed, that not the least noise was heard, nor the 
 slightest tremor felt in the building. 
 
 Mr. Valoue’s beautiful pile engiiie, employed at Westmin- 
 ster bridge, is another remarkable instance of the regulating 
 power of a fly. When the ram is dropped^ and its follower 
 disengaged immediately after it, the horses would instantly 
 tumble down, because the load, against which they had been 
 straining hard, is at once taken oft’ ; but the gin is connected 
 with a very large fly, wftiich checks any remarkable accelera- 
 tion, allowing the horses to lean on it during tiie descent of 
 the load ; after w^hich their draught recommences immedi- 
 ately. The spindles, cards, and bobbins, of a cotton mill, 
 are also a sort of flies. Indeed^ all bulky machines of the 
 rotative kind tend to preserve their motion with some degree 
 of steadiness, and their great momentum of inertia is as use- 
 ful in this respect as it is prejudicial to the acceleration or 
 any reciprocation when w^anted. There is another kind of 
 regulating fly, consisting of wings whirled briskly round, 
 till the resistance of the air prevents any great acceleration, 
 "i bis is a very bad one for a ivorking machine, for it produces 
 its effect by really wastmg a part of the moving powers. 
 Frequently it employs a very great and unknow^n part of it,. 
 and robs tlie proprietor of much work. It should never be 
 introduced into any machine employed in manufactures. 
 
 Some rare cases occur where a very dift’erent regulator is 
 required : where a certain determined velocity is found ne- 
 cessary. In this case the machine is furnished, at its ex- 
 treme mover, with a conical pendulum, consisting of two 
 heavy balls hanging by rods, which move in very nice and 
 steady joints at the top of a vertical axis. It is well known,, 
 that wdien this axis turns round, with an angular velocity 
 suited to the length of those pendulums, the time of a revolu- 
 tion is determined. Thus, if the length of each pendulum be 
 394- inches, the axis will make a revolution in two seconds 
 very nearly. If we attempt to force it more swdftly round, the 
 balls will recede a little from the axis, but it employs as long 
 time for a revolution as before ; and w^e cannot make it turn 
 swifter, unless the impelling power be increased beyond all 
 probability ; in which case the pendulum will fly out from the 
 centre till the rods are horizontal, after which every increase 
 of powder will accelerate the machine very sensibly. Watt 
 and Boulton have applied this contrivance with great inge- 
 nuity to their steam-engines, when they are employed for 
 driving machinery for manufactures which have a very change- 
 able resistance, and where a certain speed cannot be much 
 
and machinist. 
 
 51 
 
 departed from without great inconvenience. They have con- 
 nected this recess of the balls from the axis (which gives im- 
 mediate indication of an increase of power or a diminution 
 of resistance) with the cock which admits the steam to the 
 working cylinder. The balls, flying out, cause the cock to 
 close a little, and diminish the supply of steam. The impel- 
 ling power diminishes the next moment, and the balls again 
 approach the axis, and the rotation goes on as before, 
 although there may have occurred a very great excess or 
 deficiency of power. 
 
 A. fly is sometimes employed for a very different puqiose 
 from that of a regulator of motion — it is employed as a col- 
 lector of poiuer. Suppose all resistance removed from the 
 working point of a machine furnished with a very large or 
 heavy fly immediately connected with the working point. 
 When a small force is applied to the impelled point of this 
 machine, motion will begin in the machine and the fly begin 
 to turn. Continue to press, uniformly, and the machine will 
 accelerate. This may be continued till the fly has acquired a 
 very rapid motion. If at this moment a resisting body be 
 applied to the working point, it will be acted on with very 
 great force ; for the fly has now accumulated in its circum- 
 ference a very great momentum. If a body were exposed 
 immediately to the action of this circumference, it would be 
 violently struck. Much more will it be so, if the body be 
 exposed to the action of the 'working point, which, perhaps, 
 makes one turn while tlie fly makes a hundred. It will exert 
 a hundred times more force there (very nearly) than at its 
 own circumference. All the motion which has been accu- 
 mulated on the fly during the whole progress of its accumu- 
 lation, is exerted in an instant at the working point, multiplied 
 by the momentum depending on the proportion of the parts 
 of the machine. It is thus that the coining press performs 
 its office; nay, it is thus that the blacksmith forges a bar of 
 iron. Swinging the great sledge hammer round his head, 
 and urging it with force the whole way, this accumulated 
 motion is at once extinguished by impact on the iron. It 
 is thus also we drive a nail, &c. This accumulating power 
 of a fly has occasioned many to imagine that a fly really 
 adds power or mechanical force to an engine; and, not under- 
 standing on what its efficacy depends, they often place the 
 fly in a situation where it only adds a useless burden to the 
 machine. It should always be made to move with rapidity. 
 If intended for a mere regulator, it should be near the first 
 mover ; and if it be intended to accumulate force in the 
 
52 
 
 TMK OPERATIVE MKCPIANIC 
 
 working point, it should not !>e far separated from it. In a 
 certain sense, a fly may be said to add power to a machine, 
 because by accumulating into the exertion of one moment the 
 exertions of many, we can sometimes overcome an obstacle 
 that we never could have balanced by the same machine, 
 unaided by the fly. And it is this accumulation of force 
 M^hich gives such an appearance of power to some of our 
 first movers. 
 
 ANIMAL STRENGTH. 
 
 Animal strength has been very differently estimated by 
 different authors ; but this is not to be wondered at when we 
 consider the many difficulties that ever must attend any 
 attempt to subject it to an estimate. Physical causes must 
 sensibly affect the extent and duration of animal exertion, 
 either in man or beast ; and the only way of coming to any 
 thing like an accurate result, is to compare the experiments 
 of the different philosophers who have attended to the sub- 
 ject. This has been already done by Dr. Young, in the 
 second volume of his Philosophi/, whose valuable tables we 
 here present to our readers. 
 
 Comparative table of mechanical forces. 
 
 In order to compare the different estimates of the force of 
 moving powers, it will be convenient to take a unit which 
 may be considered as the mean effect of the labour of an 
 active man, working to the greatest possible advantage, and 
 v'ithout impediment. This will be found, on a moderate 
 estimation^ sufficient to raise lOpounds, 10 feet in a second, 
 for ten hours in a day; or to raise a 100 pounds, which is the 
 weight of twelve wine gallons of water, one foot in a second, 
 or 36,000 feet in a day ; or 3,600,000 pounds, or 432,000 
 gallons, one foot in a day. This we may call a force of one 
 continued 36,000'' 
 
 Immediate force of men, without deduction for friction. 
 
 A mnn, weigliing 133 pounds, Fr. ascended 62 feet, Fr, 
 by steps, in 34", but was completely exhausted.— 
 
 Aiuontons 
 
 A sawyer made 200 strokes of 18 inches, Fr. each, in 
 145", with a force of 25 pounds, Fr. He could not have 
 
 gune on above three minutes. — Amontons. 
 
 A man can raise 60 pounds, Fr. one foot, Fr. in 1", for 
 
 eight hours a day. — Bernouilii 
 
 A man of ordinary strength can turn a winch with a 
 force of 30 pounds, and with a velocity of 3$ feet in 1", 
 for 10 hours a day. — Desaguliers 
 
 Force. 
 
 Conti- 
 
 nuance. 
 
 Day’s 
 
 work. 
 
 00^ 
 
 W' 
 
 
 6 
 
 145 
 
 
 69 
 
 
 ,552 
 
 1,05 
 
 lOh 
 
 1,05 
 
AND MACHINIST. 
 
 ^3 
 
 , T\vo men working at a wimUass with handles at right 
 angles, can raise 70 pounds more easily than one can 
 
 raise 30. — Desaguliers 
 
 A man can exert a force of 40 pounds for a whole day, 
 with the assistance of a fly, when the motion is pretty quick, 
 at about four or five feet in 1".- -Desaguliers, Lect. iv. 
 But from the annotation it appears to be doubtful whether 
 
 the force is 40 pounds or 20 
 
 For a short time a man may exert a force of 80 pounds 
 wdth a fly, “ when the motion is pretty quick." — Desa- 
 
 guliers 
 
 A man going i:p stairs ascends 14 metres in I'. — Cou- 
 lomb 
 
 A man going up stairs for a day raises 205 chiliogrammes 
 
 to the height of a chilioinctre. — Coulomb 
 
 With a spade a man does ^ as much as in ascending 
 
 stairs. — Coulomb . . 
 
 With a winch a man does f as much as in ascending 
 
 stairs. — Coulomb 
 
 A man carrying wmod up stairs raises, together with 
 his own weight, 109 chiliogrammes to one chiliometre. — 
 
 Coulomb 
 
 A man weighing 150 pounds, Fr. can ascend by stairs 
 
 three feet, Fr. in 1" for 15" or 20".— Coulomb 
 
 For half an hour, 100 pounds, Fr. may be raised one 
 
 foot, Fr. in 1". — Coulomb 
 
 According to Mr. Buchanan’s comparison, the force 
 exerted in turning a winch being made equal to the unit, 
 
 the force in pumping will be 
 
 In ringing 
 
 In rowing 
 
 Allowing the accuracy of Euler’s formula, confirmed by 
 Schulze, supposing a man’s action to be a maximum when 
 he w’alks miles an hour, we have 7^ for his greatest 
 velocity, ,04f7f— r)" for the force exerted with any other 
 velocity, and ,0160(7^ — for the action in each case; 
 thus, when the velocity is one mile an hour, the action is 
 
 When two miles 
 
 When three 
 
 When four 
 
 And when five 
 
 Force. 
 
 Cunti- 
 
 nuance. 
 
 Daj’s 
 
 work. 
 
 1,22 
 
 
 1,22 
 
 ,2 
 
 
 ,2 
 
 ,3 
 
 1" 
 
 
 1,1 8;2 
 
 1' 
 
 ,4i2 
 
 'XV 1 
 
 
 
 ,258 
 
 
 
 ,219 
 
 5,22 
 
 20" 
 
 
 1,152 
 
 30' 
 
 
 ,61 
 
 1,36 
 
 1,43 
 
 
 
 ,676 
 
 ,964 
 
 ,972 
 
 ,784 
 
 >5 
 
 
 
 And the force in a state of rest becomes 2^, or about 
 70 pounds ; with a velocity of two miles, 36 pounds ; with 
 three, 24 pounds; and with four, 15. 
 
 It is obvious that in the extreme cases this formula is in- 
 accurate, but for moderate velocities it is probably a tolerable 
 approximation. 
 
 Coulomb makes the maximum of effect when a man, 
 weighing JO chiliogrammes, carries a w’eight of 53 up stairs, 
 but this appears to be too great a load ; he considers 145 
 chiliogrammes as the greatest ^^eight that can be raised. 
 He observes that in Martinique, where the thermometer is 
 seldom below 68°, the labour of Europeans is reduced to one 
 
54 
 
 THE OPERATIVE MECHANIC 
 
 Harriot asserts tliat his pump, with a horizontal motion, 
 enables a man to do one-third more work than the common 
 pump with a vertical motion. 
 
 Porters carry from 200 to 300 pounds at the rate of three 
 miles an hour ; chairmen walk four miles an hour with a load 
 ,of 150 pounds each; and it is said that in Turkey there are 
 porters who, by stooping forward, carry from 700 to 900 
 pounds placed very low on their backs. 
 
 The most advantageous weight for a man of common 
 strength to carry horizontally, is 1 1 1 pounds ; or if he returns 
 unladen, 135. With wheel-barrows, men will do half as 
 much more work as with hods. — Coulomb. 
 
 Performance of men by machines. 
 
 A man raised by a rope and pulley 25 pounds, Fr. 220 
 
 feet, Fr. in 145''. — Amontons 
 
 A man can raise, by a good common pump, a hogshead 
 of water 10 feet high in a minute, for a whole day.— 
 
 DesaguUers. 
 
 By the mercurial pump, or any other good pump, a man 
 may raise a hogshead 18 or 20 feet in a minute, for om 
 
 or two minutes 
 
 In a pile engine, 55^ pounds, Fr. were raised one'foot 
 Fr. in 1" for five hours a day, by a rope drawn horizon- 
 tally. — Coulomb 
 
 Robison says, that a feeble old man raised seven cubic 
 feet of water, 11§ feet in 1', for eight or ten hours a day, 
 by walking backwards and forwards on a lever. — Eiic. Br. 
 
 A young man weighing 135 pounds, and carrying 30, 
 raised 9^ cubic feet, 11^ feet high, for 10 hours a day, 
 
 without fatigue. — Robison 
 
 Wynner’s machine enables a man to raise a hogshead 20 
 feet in a minute.— Y 
 
 Force of horses. 
 
 Two horses, attached to a plough on moderate ground, 
 exerted each a force of 150, Fr. — Amontons. We may 
 suppose that they went a little more than two miles an 
 
 iiour, for eight hours 
 
 A horse draws with the greatest advantage when the line 
 of direction is level with his bteast ; and he can draw with 
 a force of 200 pounds, 2§ miles an hour, for eight hours 
 
 in the day 
 
 With a force of 240 only six hours. On a carriage, in- 
 deed, where friction alone is to be overcome, a middling 
 
 horse will draw 1000 pounds. — DesaguUers 
 
 The mean draught of four horses was 36 myriogrammes 
 each, or 794 pounds. — Regnier. This must have been mo- 
 mentary. Supposing the velocity two feet in a second, the 
 
 action would have been 
 
 By means of pumps a horse can raise 250 hogsheads of 
 water, 10 feet high, in an hour. — Smeaton’s Reports .... 
 
 Force. 
 
 Conti- 
 
 nuance. 
 
 Day ’3 1 
 work. 
 
 ,436 
 
 145 " 
 
 
 ,875 
 
 
 ,875 
 
 1,61 
 
 J/ 
 
 
 ,64 
 
 5 ^ 
 
 ,82 
 
 ,837 
 
 9 >* 
 
 ,753 
 
 1,106 
 
 lOh 
 
 1,106 
 
 1,75 
 
 1 ' 
 
 
 5,4 
 
 8 ^ 
 
 4,32 
 
 7,33 
 
 8 b 
 
 5,87 
 
 8,8 
 
 6 b 
 
 5,28 ' 
 
 15,88 
 
 1" 
 
 
 3,64 
 
 1 " 
 
 
AND MACHINIST. 
 
 55 
 
 A horse can in general draw no more up a steep hill than 
 three men can carry ; that is, from 450 to 750 pounds j but 
 a strong horse can draw 2000 pounds up a steep hill, which is 
 but short. Tlie worst way of applying the force of a horse, is 
 to make him carry or draw up hill ; for if the hill be steep, 
 three men will do more than a horse, each man climbing up 
 faster with a hurdeii of 100 pounds weight, than a horse that 
 is loaded with 300 pounds : a difference which is owing to 
 the position of the parts of the human body being better 
 adapted to climb than those of a horse. 
 
 On the other hand, the best way of applying the force of 
 a horse, is an horizontal direction, wherein a man can exert 
 least force; thus a man, weighing 140 pounds, and drawing 
 a boat along, by means of a rope coming over his shoulders, 
 cannot draw above 2J pounds, or exert above one-seventh 
 part of the force of a horse employed to the same purpose. 
 
 The very best and most effectual posture in a man is tliat 
 of rowing ; wherein he not only acts with more muscles at 
 once for overcoming the resistance than in any other position, 
 but as he pulls backwards, the weight of his body assists by 
 way of lever. — Desaguliers. 
 
 The diameter of a walk for a horse-mill ought to be at least 
 25 or 30 feet. — Desaguliers. 
 
 Some horses have carried 650 or /OO pounds, seven or 
 eight miles, without resting, as their ordinary work ; and a 
 horse at Stourbridge carried eleven hundred weight of iron, 
 or 1232 pounds, for eight miles. — Desaguliers, Experimental 
 Philosophy, vol. i. 
 
 Work of mules. 
 
 Force. 
 
 Cazancl s.ays, that a mule works in the West Indies two 
 hours out of about 18, with a force of about 150 pounds, 
 walking three feet in a second. — Dr. Young’s Philosophy 4,5 
 
 These examples exhibit the great advantages which may 
 be gained by directing the exertion of animals in a proper 
 course, their effects being plainly reducible to the operations 
 of mechanical powers. To describe the various modes of 
 applying animal strength, as a first mover of mechanical en- 
 gines, would greatly exceed our limits ; we shall therefore 
 merely state, that the most common machine for receiving 
 the force of animals is the horse-walk, w hich affords tiie means 
 of applying the action of that animal to create rotative motion. 
 The horse-walk is formed of an horizontal lever or arm, 
 attached to an upright spindle. The lever should not be less 
 
 Cr>nti- Day’s 
 nuance, woik. 
 
 40' 1,2 
 
66 
 
 THE OPERATIVE MECHANIC 
 
 than twelve feet^ as the labour of the animal is greatly in- 
 creased by a small curve^ which causes an unequal resistance 
 upon his two shoulders. The machine should be so regulated 
 that the horse may not be required to deviate from his usual 
 pace of two miles and a half, with a burthen, an hour. The 
 gives, in which the horse works, should not be immovably 
 fixed to the arms, but hung by a swivel joint, so that he 
 may place himself in the most comfortable position. The 
 work should be supplied to the machinery as regularly as 
 possible. 
 
 Having, in the preceding account, stated the mean results 
 of human exertion when applied to regular and uniform 
 labour, we shall in the next place proceed to notice some 
 extraordinary feats of strength, as well as some that had the 
 appearance of being such, but which were, in realit}', the 
 mere effects of contrivance and skill, and which might have 
 been performed by almost any men who were possessed 
 of that knowledge of their construction as would enable them 
 similarly to exert their strength to the best advantage. 
 
 M. de la Hire, in an Examination of the Force of Men ^ 
 (vide Memoirs of the Academy of Sciences for 1699,) says. 
 
 There are men whose spirits flow so abundantly into their 
 muscles, that they exert three or four times more strengtli 
 than others do ; and this seems to be the natural reason of 
 the surprising strength that we see in some men who carry 
 and raise weights which two or three ordinary men can 
 hardly sustain, though these men be sometimes but of a 
 moderate stature, and rather appear weak than strong. 
 There was a man in this country a little while ago, who 
 would carry a very large anvil, and of whom was reported 
 several wonderful feats of strength. But I saw another at 
 Venice, who was but a lad, and did not seem able to carry 
 above forty or fifty pounds, with all possible advantages; yet 
 this young fellow, standing upon a table, raised from the 
 earth, and sustained off the ground, an ass, by means of a 
 broad girth, which, going under the creature’s belly, w^as hung 
 upon two hooks that were fastened to a plat of small cords 
 coming down in tresses from the hair on each side of the 
 lad’s head, which were in no great quantity. And all this 
 great force depended only upon the muscles of the shoulders 
 and those of the loins: for he stooped at first whilst the 
 hooks w'ere fastened to the girth, and then raised himself, and 
 lifted up the ass from the ground, bearing with his hands 
 upon his knees. He raised also in the same manner other 
 weights that seemed heavier, and used to say he did with 
 
AND MACHINIST. 
 
 Diore ease, because the ass kicked and struggled when first 
 lifted from the gTound.” 
 
 Dr, Desaguliers, in some annotations upon De la Hire’s 
 paper, says, What he attributes here to the muscles of the 
 loins, -were really performed by the extensors of the legs ; for 
 the young man’s stooping with his hands upon his knees was 
 not with his body forwards and his knees stiff, but his body 
 upright and his knees bent, so as to bring the two cords with 
 which he lifted to be in the same plane with his ancles and 
 the heads of his thigh-bones ; by which means the line of 
 direction of the man and the whole weight came between the 
 strongest part of his two feet, which are the supports : then 
 as he extended his legs he raised himself, without changing 
 the line of direction. That this must have been the manner 
 I am pretty well assured of, by not only observing those that 
 perform such feats, but having often tried it myself. As for 
 the muscles of the loins, they are incapable of that strain, 
 being above six times weaker than the extensors of the legs ; 
 at least 1 found them so in myself. 
 
 “About the year IJIG, having the honour of showing a 
 great many experiments to his late majesty King George I., 
 his majesty was desirous to know wdiether there were any 
 fallacy in those feats of strength that had been shown half 
 a year before by a man, who seemed by his make to be no 
 stronger than other men : upon this I had a frame of wood 
 made to stand in, (and to rest my hands upon,) and with a 
 girdle and chain lifted an iron cylinder, made use of to roll 
 the garden, sustaining it easily when once it was up. Some 
 noblemen and gentlemen who were present -tried the ex- 
 periment afterwards, and lifted the roller; some with more 
 ease, and some with more difficulty, than I had done. This 
 roller weighed 1,900 pounds, as the gardener told us. 
 Afterwards I tried to lift 300 pounds with my hands, (viz., 
 two pails with 150 pounds of quicksilver in each,) which 
 I did indeed raise from the ground, but strained my back 
 so as to feel it three or four days ; which shows that, in the 
 «ame person, the muscles of the loins (which exerted their 
 force in this last experiment) are more than six times 
 weaker than the extensors of the legs ; for I felt no incon- 
 veniency from raising the iron roller.” 
 
 During the time that Dr. Desaguliers was occupied in 
 printing the second volume of his Philosophy, a man of great 
 natural strength exhibited himself in London, of whom the 
 doctor gives the following account. 
 
58 
 
 THE OPERATIVE MECHANIC 
 
 ‘‘ Thomas Popham, born in London, and now about thirty- 
 one years of age, five feet ten inches high, Avith muscles very 
 hard and prominent, was brought up a carpenter, which trade 
 he practised till within these six or seven years that he has 
 showed feats of strength; but he is entirely ignorant of any 
 art to make his strength more surprising. Nay, sometimes 
 he does things which become more difficult by his disadvan- 
 tageous situation ; attempting, and often doing, what he hears 
 other strong men have done, without making use of the same 
 advantages. 
 
 ‘‘About six years ago he pulled against a horse, sitting upon 
 the ground with his feet against Uvo stumps driven into the 
 ground, but without the advantages which might have been 
 attained by placing himself in a proper situation ; the horse, 
 however, was not able to move him, and he thought he was 
 in the right posture for drawing against a horse ; but when, 
 in the same posture, he attempted to draw' against two horses, 
 he was pulled out of his place by being lifted up, and had 
 one of his knees struck against the stumps, which shattered 
 it so, that, even to this day, the 'patella^ or knee-pan, is so 
 loose, that the ligaments of it seem either to be broken or 
 quite relaxed, which has taken aAvay most of the strength of 
 Slat leg.’’ 
 
 Dr. Desaguliers then relates the exploits which he saw him 
 perform. 
 
 “ 1. By the strength of his fingers, (only rubbed in coal 
 ashes to prevent them from slipping,) he rolled up a very 
 strong and large pewter dish. 
 
 “ 2. He broke seven or eight short and strong pieces of 
 tobacco-pipe with the force of his middle finger, having laid 
 them on the first and third finger. 
 
 “ 3. Having thrust in under his garter the bowl of a strong 
 tobacco-pipe, his legs being bent, he broke it to pieces by the 
 tendons of his hams, without altering the bending of his knee. 
 
 “ 4. He broke such another bowl between his first and 
 second finger, by pressing his fingers together sideways. 
 
 “ 5. He lifted a table six feet long, which had half a hundred 
 weight hanging at the end of it, with his teeth, and held it in 
 an horizontal position for a considerable time. It is true, 
 the feet of the table rested against his knees; but, as the 
 length of the table was much greater than its height, that 
 performance required a great strength to be exerted by the 
 muscles of his loins, those of his neck, the masseter and tem^ 
 poraly (muscles of the jaws,) besides a good set of teeth. 
 
AND MACHINIST 
 
 59 
 
 6. He took an iron kitchen poker, about a yard long, and 
 three inches in circumference, and, holding it in his right 
 hand, he struck upon his bare left arm, between the elbow 
 and the wrist, till he bent the poker nearly to a right angle. 
 
 7* He took such another poker, and holding the ends of it 
 in his hands, and the middle against the back of his neck, he 
 brought both ends of it together before him ; and, what was 
 yet more difficult, he pulled it almost straight again : because . 
 the muscles which separate the arms horizontally from each 
 other are not so strong as those that bring them together. 
 
 8. He broke a rope of about two inches in circumference, 
 which was in part wound about a cylinder of four inches 
 diameter, having fastened the other end of it to straps that 
 went over his shoulders. But he exerted more force to do 
 this than any other of his feats, from his awkwardness in 
 going about it; for the rope yielded and stretched as he stood 
 upon the cylinder, so that when the extensors of the legs and 
 thighs had done their office in bringing his legs and thighs 
 straight, he was forced to raise his heels from their bearings, 
 and use other muscles that are weaker. But if the rope had 
 been so fixed that the rope to be broken had been short, it 
 would have been broken with four times less difficulty. 
 
 9. I have seen him lift a rolling stone of about 800 
 pounds with his hands only, standing in a frame above it, 
 and taking hold of a chain that was fastened to it. By this, 
 I reckon, he may be almost as strong again as those who 
 are generally reckoned the strongest men, they generally 
 lifting no more than 400 pounds in that manner. The 
 weakest men who are in health, and not too fat, lift about 
 125 pounds, having about half the strength of the strongest. 
 
 N. B. This sort of comparison is chiefly in relation to the 
 muscles of the loins; because in doing this, one must stoop 
 forwards a little. We must also add the w^eight of the body 
 to the weight lifted. So that if the weakest man’s body 
 weighs 150 pounds, that, added to 125 pounds, makes the 
 whole weight lifted by him to be 275 pounds. Then, if the 
 strongest man’s body weighs also 150 pounds, the whole 
 weight lifted by him will be about 550 pounds, that is 400 
 pounds and the 150 pounds which his body weighs. Top* 
 ham weighs about 200 pounds, which, added to the 800 
 pounds that he lifts, makes 1000 pounds. But he ought to 
 lift 900 pounds besides the weight of his body, to be as 
 strong again as a man of 150 pounds weight w'ho can lift 
 400 pounds. 
 
 “ About thirty years ago, one Joyce^ a Kentish man, famous 
 
C') THE CTERATIVE MECHANIC 
 
 for his great strength, showed several feats in London and the 
 country, which so much surprised the spectators, that he was 
 ])y most people called the second Sampson, But though 
 tiie postures which he had learnt to put his body into, and 
 found out by practice, without any mechanical theory, were 
 such as would make a man of common strength do such feats 
 as would appear surprising to every one who did not know 
 the advantage of those positions of the body, yet nobody 
 then attempted to draw against horses, or raise great weights, 
 or to do any thing in imitation of him ; because, as he was 
 very strong in the arms, and grasped those that tried his 
 strength tnat way so hard that they were obliged immediately 
 to desire him to desist, his other feats (wherein his manner of 
 acting was chiefly owing to the mechanical advantage gained 
 by the position of his body,) were entirely attributed to his 
 extraordinary strength. 
 
 But when he had been gone out of England, or had ceased 
 to show his performances, for eight or ten years, men of 
 ordinary strength had found out the way of making such 
 advantage of the same postures as Joyce had put himself into, 
 as to pass for men of more than common strength, by draw- 
 ing against horses, breaking ropes, lifting vast weights, &c., 
 though they could in none of the postures really perform so 
 much as Joyce, yet they did enough to amaze and amuse, 
 and get a deal of money, so that every two or three years we 
 had a new second Sampson. 
 
 About fifteen years ago a German of middle size, and but 
 ordinary strength, showed himself at the lUue Posts, in the 
 Haymarket, and, by the contrivances above-mentioned, passed 
 for a man of uncommon strength, and gained considerable sums 
 of money by the daily concourse of spectators. After having 
 seen him once, I guessed at his manner of imposing upon the 
 multitude; and being resolved to be fully satisfied in th3 
 matter, I took four very curious persons with me to see him 
 again, viz., the Lord Marquis of Tullibardin, Dr. Alexander 
 Smart, Dr Pringle, and a mechanical workman who used to 
 assist me in my courses of experiments. We placed our- 
 selves in such manner round the operator, as to be able to 
 observe nicely all that he did; and found it so practicable, 
 that we performed several of his feats that evening by our- 
 selves, and afterwards I did the most of the rest, as 1 had a 
 frame to sit in to draw, and another to stand in and lift 
 weights, together with a proper girdle and hooks. I likewise 
 showed some of the experiments before the Royal Society; 
 and ever since, at my experimental lectures, I explain the 
 
AND MACHf^sfST. 
 
 6f 
 
 reason of such performances, and take any person of ordinary 
 strength that has a mind to try, who can easily do all that the 
 German above-mentioned used to do, without any danger or 
 extraordinary straining, by making use of my apparatus for 
 that purpose. 
 
 In order to explain how great feats may be performed by 
 men of no extraordinary strength, I have in fig. 79^ drawn 
 the lower part of a skeleton, containing so many of the bones 
 of the human body as are concerned in these operations, 
 making the figure pretty large, to show the better how the 
 girdle is to be applied. 
 
 “ The bones marked I Sx\PH I,* which compose the cavity 
 called the pelvis, contain a bony circle or double arch of such 
 strength, that it would require an immense force to break 
 them by an external pressure directed towards the centre of 
 the circle, or the middle of the pelvis. It is also to be 
 observed, that those parts of this bony circumference, which 
 receive the heads of the thigh-bone above, at, and below A, 
 called the ischium or coxendix, are the strongest of all, so 
 that a very great force may push the heads of the thigh-bones 
 upwards, or, which is the same thing, the upper parts of the 
 coxendix downwards, or towards each other in a lateral 
 direction from A to A, without doing any hurt to the human 
 body. 
 
 Now if the girdle above described be put round the body 
 in the manner represented in the figure, and be drawn dowui- 
 wards at G, by a great weight W, it wull press on the os 
 sacrum behind, and the ilium; then it will, by its pressure on 
 TT, the great trochanters of the thigh-bones, draw the round 
 heads the faster into their sockets, so as to make them less 
 liable to slip out and strain the ligament by a push directed 
 upwards. So that the semicircular part of the girdle, T C S C T, 
 presses together the bony arch denoted by the same letters, 
 which, according to the nature of arches, is the stronger for 
 that pressure. The abutments of the arch cannot come 
 nearer together by reason of the resistance of the strong 
 bones A P A, neither can they fly outwards, because the 
 girdle keeps them together. Then the thighs and legs T D B 
 are two strong columns, capable of sustaining 4000 or 5000 
 
 These bones are thns distinguished by anatomists : S, the os sacrum ; 
 1 1, the ilium; A A, the os ischium; whose strongest part has on each sido 
 an hemispherical concave, in which the round head of the thigh-bone is 
 received and turns round, being held by a strong ligament in its middle ; 
 those parts of the bone that join together before, betwixt A A and above P, 
 are called the os pubis, or ossa pubis. 
 
62 
 
 THE OPERATIVE MECHANIC 
 
 pounds at least, provided they stand quite upright. The 
 muscles here are put to no strain, being no farther concerned 
 than to balance each other; that is, the antagonist muscles, 
 extensors, and flexors, only keep the bones in their place, 
 which makes them resist like one entire bone formed into an 
 arch. 
 
 This shows how easily the man, fig. 80, may sustain a 
 cannon of 2000 or 3000 pounds weight. The same solution 
 will also serve for the resistance of the man, fig. 81, whom 
 five men, nay ten men, or two horses, cannot puli out of his 
 situation when he sits so as to have his legs and thighs in 
 the horizontal line P F, or in a line inclining downwards 
 towards A, for then, though there is a difterence in the sitting- 
 posture from the standing posture before described, yet by 
 reason of the mobility of the heads of the thigh-bones in the 
 acetabula or cavities of the coxendix, the arch is the same 
 and as strong as before, its abutments being equally sup- 
 ported by the legs and thighs. It is only the bending of the 
 back-bone above the girdle to bring up the body which makes 
 the difference of position in the man, though not sensibly in 
 the resisting parts. 
 
 In breaking a rope the muscles must act in extending the 
 legs; and that we may the better explain that action, we must 
 consider a man breaking the rope, as represented in fig. 82. 
 Suppose a rope fastened to a post at P, or any other fixed 
 point, is brought through an iron eye L, to the hook of the 
 girdle H, of the man H I, and so fixed to it by a loop, or 
 otherwise, as to be quite tight, whilst the man’s knees are so 
 bended as to want about an inch of having his legs and 
 thighs quite upright. Then if the man on a sudden stretches 
 his legs and sets himself upright, he will with ease break the 
 very same rope which held two horses exerting their whole 
 strength when they drew against him ; such as a cart rope, 
 or a rope of near three quarters of an inch diameter, which 
 may be broken by a man of middling strength, by the action 
 of the ten muscles * that extend the legs, five belonging to 
 each leg. 
 
 * The four muscles tliat extend eacli leg are described by anatomists 
 thus : — 1. The rectus, arising from the anterior inferior spine of the os ilium, 
 and inserted, through the medium of the patella, into the anterior tuberosity 
 of the tibia. 2. The oruralis, situated beneath the former, and arising from 
 the front surface of the os femoris for a considerable extent, and inserted 
 into the upper edge of the patella, and also, through the medium of that bone, 
 into the anterior tuberosity of the tibia. 3. The vastus externus, arising from 
 the root of the trochanter major, and outer side of the os femoris, and in- 
 serted into the outer edge of the patella, and again, through its medium, into 
 the anterior tuberosity of the tibia. 4. The vastus internus, which arises from 
 

 
AND MACHINIST. 
 
 G3 
 
 In brcaldng the rope one thing is to be observed, which 
 will much facilitate the performance ; and that is, to place the 
 iron eye L, through which the rope goes, in such a situation, 
 that a plane going through its ring shall be parallel, or nearly 
 parallel to the two parts of the rope; because then the rope 
 will in a manner be jammed in it, and not slipping through 
 it, the whole force of the man’s action will be exerted on 
 that part of the rope which is in the eye, M^hich will make it 
 break more easily than if more parts of the rope were acted 
 upon. So that the eye, though made round and smooth, may 
 be said in some measure to cut the rope. And it is after this 
 manner that one may break a whip-cord, nay, a small jack- 
 line, with one’s hand, without hurting it; only by bringing 
 one part of the rope to cut the other ; that is, placing it so 
 round one’s left hand, that, by a sudden jerk, the whole force 
 exerted shall act upon one point of the rope. See fig. 83, 
 where the cord to be broken at the point L in the left hand, 
 is marked according to its course, by the letters R T S L M 
 N O P Q, folding once about the right hand, then going under 
 the thumb into the middle of the left hand ; w^here crossing 
 under another part, it is brought back under the thumb again 
 to M, then round the back of the hand to N, so through the 
 loop at L to O, and three times round the little finger at P 
 and Q; which last is only that the loop N O may not give 
 way. Before the hands are jerked from one another, the left 
 hand must be shut, but the thumb must be' held loose, lest 
 pressing against the fore finger it should hinder the part T L 
 of the rope from carrying the force fully to the point L ; but 
 the little finger and that next to it must be held hard, to 
 keep the loop N O firm in its place. 
 
 There are several cases, wherein it would be of singular 
 use to apply the force of one or more men, by means of the 
 girdle or hook and chain, in the manner above-mentioned ; 
 as for example, wdien the resistance is very great, but the 
 bodies that resist are to be removed but a little way: if we 
 lift very heavy goods a small height, to remove any thing from 
 under them ; if we would draw a bolt or staple, and find we 
 cannot do it even with an iron crow, the hand pulling it 
 upwards at the end ; then the hook of the girdle being applied 
 at the end of the crow, the force exerted by stretching the 
 legs would be tenfold of what the hands were able to do, 
 without more help at the same place. 
 
 “ There may also be many occasions on board a ship. I will 
 
 the root of the trochanter minor, and inner surface of the os femoris, and 
 inserted into the inner edge of tlie patella, and likewise, through its medium, 
 into the anterior tuberosity of tire tibia with the former rauscles. 
 
04 
 
 THE OPERATIVE MECHANIC 
 
 instance but one. Let F G, fig. 84, be the tackle for raising 
 or lowering the main -top -mast, part of which is represented 
 by m 1, the block G is fixed below, and as the block F 
 comes down, it pulls along with it the top rope F B C, 7n 1 
 running over the block B, fixed at A, and round the block C 
 in the heel of the top-mast, so as to draw up the lower end 
 m 1 of the said main-top-mast, which, when hoisted up to its 
 due height, is made fast by the iron pin or fid I, which is 
 thrust through it, and then its own weight and the hole D of 
 the cap will keep it in its place. We will suppose that the 
 force required thus to raise the mast must be that of six men 
 pulling upon deck at the fall of the tackle, that is, at the 
 running rope F G K at K on the other side of the main-mast 
 L /. Now in order to let down this mast on the sudden, as 
 in case of hard weather, it is necessary the tackle and power 
 must be made use of, though it be but to lift it a very little 
 way, that a man may be able to get out the fid 1, before the 
 said mast can be let down and slip to N on the side of the 
 main-mast. I say, that if the hands are so employed other- 
 wise, that instead of six men there be only one man at the 
 rope K; if he has a strong girdle to which he fastens it, or 
 makes a bow in the rope itself, to fix it round the lower part 
 of his back, &c., he may exert much more force in the direc- 
 tion GK than the sLx men in the common way of pulling; 
 and if he draws to him, sitting on the ground, and pushing 
 his feet against the first firm obstacle that he finds, as against 
 O P, only two inches of the rope G K, he will raise up the 
 main-top-mast the third part of an inch, which will be sufii- 
 cient for the iron fid I to be drawui out.’' Desaguliers’ 
 Philosophy, vol. i. 
 
 VVATER- MILLS. 
 
 Water-mill is the name by w hich all mills are designated 
 that receive their motion from the impulse of the water. 
 As each of these mills wdll come under their respective heads, 
 w'e shall, in the present article, confine ourselves to a minute 
 description of the difterent kinds of water-wheels, by whose 
 axis the force wdth wdiich they have been impressed may be 
 transmitted to move any species of machinery, however simple 
 or complex. 
 
 But, notwithstanding the extensive signification of the 
 term water-mill when applied to the different branches of 
 manufacture carried on therein, we have another, and still 
 more simple division, arising from the peculiar construction 
 of the w'ater-wLeel, termed the undershot-mill, the overshot- 
 
AND MACHINIST. 
 
 65 
 
 mill, and the breast-mill. There is also another called the mill 
 \vith horizontal wheels ; but as this i^ very disadvantageous 
 in point of practical utility, we shall forbear to describe it. 
 The under shot-w heel is used only in streams, and is acted 
 upon by the water striking the float-boards at the lower 
 circumference of the wheel. In the over shot-wheel the water 
 is poured over the top of the wheel, and is received in buckets 
 fonned all round the w'heel for that purpose. And in the 
 hreast-ivheel the water falls down upon the wheel at right 
 angles to the float-boards, or buckets placed round the 
 circumference of the wheel to receive it. 
 
 UNDERSHOT-WHEELS. 
 
 Mr. John Smeaton has made mimerous experiments upon 
 tlie different kinds of w’ater- wheels, the results of which were 
 laid before the Royal Society. The time that has elapsed 
 since the period when they w ere first given to the world, has 
 been sufficient to prove their fallacy, if any had existed ; and 
 the high estimation in which they still continue to be held by 
 mathematicians and mechanics, is certain evidence of their 
 value and importance. 
 
 Mr. Smeaton prefaces a minute description of the machines 
 and models used by him for his experiments, wdth an observ- 
 ation, that what he has to communicate on the subject was 
 originally deduced from experiments, wffiich he looks upon 
 as the best means of obtaining the outlines in mechanical 
 inquiry. “ But in such cases,” says he, it is very necessary 
 to distinguish the circumstances in which a model differs 
 from a machine in large ; otherwise a model is more apt to 
 lead us from the truth than towards it : and, indeed, though 
 the utmost circumspection be used in this way, the best 
 structure of machines cannot be fully ascertained but by 
 making trials wnth them, when made of their proper size. 
 It was for this reason, though the models and experiments 
 referred to were made in the years 1752 and 1753, that I 
 have deferred offering them to the Society until I had an 
 opportunity of putting the deductions made therefrom in real 
 practice, in a variety of cases, and for various purposes, so as 
 to be able to assure the Society that I have found them to 
 answer.'" 
 
 Mr. Smeaton then remarks, that the v/oxd. power y as used in 
 practical mechanics, signifies the exertion of strength, gra- 
 vitation, impulse, or pressure, so as to produce motion; and 
 by means of strength, gravitation, impulse, or pressure, com- 
 pounded w ith motion, to be capable of producing an eflect ,■ 
 
66 
 
 THE OPERATIVE MECHANIC 
 
 and that no effect is properly mechanical, but what requires 
 such a kind of power to produce it. 
 
 Having described the models and machines used for making 
 his experiments, he observes that with regard to power, it is 
 most properly measured by the raising of a w^eight, the 
 relative height to which it can be raised in a given time 
 being the actual extent; or, in other words, if the weight 
 raised be multiplied by the height to which it can be raised 
 in a given time, the product is the measure of the power 
 raising it; and, consequently, all those powers are equal, 
 whose products, made by such multiplication, are the same ; 
 for if a power can raise twdce the weight to the same height, 
 or the same weight to twice the height, in the same time 
 that another power can, the first power is double the second ; 
 but if the power can only raise half the w'eight to double the 
 height, or double the weight to half the height, in the same 
 time that another can, those two powers are equal. This, 
 however, must be understood to be only in cases of slow and 
 equable motion, where there is no acceleration or retardation. 
 
 In comparing the effects produced by water-wheels with 
 the powers producing them, or, in other words, to know 
 what part of the original power is necessarily lost in the 
 application, we must previously know how much of the power 
 is spent in overcoming the friction of the machinery and the 
 resistance of the air; also, what is the real velocity of the 
 water at the instant that it strikes the wheel, and the real 
 quantity of water expended in a given time. 
 
 From the velocity of the water at the instant that it strikes 
 the wheel, the height of head productive of such velocity 
 can be deduced, from acknowledged and experimented prin- 
 ciples of hydrostatics: so that. by multiplying the quantity 
 or weight of water really expended in a given time, by the 
 height of a head so obtained, which must be considered as 
 the height from which that weight of water had descended 
 in such given time, we shall have a product equal to the 
 original power of the water, and clear of all uncertainty that 
 would arise from the friction of the water, in passing small 
 apertures, and from all doubts arising from the different 
 measure of spouting waters, assigned by different writers. 
 
 On the other hand, if the sum of the weights raised by the 
 action of this water, and of the weight required to overcome 
 the friction and resistance of the machine, be multiplied by the 
 height to which the weight can be raised in the time given, 
 the product will be equal to the effect of that power; and 
 the proportion of the two products will be in proportion of 
 
AND MACHINIST. 
 
 07 
 
 the poiver to the effect : so that by loading the wheel with 
 different weights successively, we shall be able to determine 
 at what particular load, and velocity of the wheel, the effect 
 is a maximum. 
 
 The experiments made by Mr. Smeaton may thus be 
 reduced. The circumference of the wheel, 75 inches, mul- 
 tiplied by 86 turns, gives 6450 inches for the velocity of the 
 water in a minute; of which will be the velocity in a 
 second, equal to 107.5 inches, or 8.96 feet, which is due to a 
 head of 15 inches; and this w^e call the virtual or effective 
 head. The area of the head being 105.8 inches, this mul- 
 tiplied by the weight of water of the cubic inch, equal to 
 the decimal 579 of the ounce avoirdupois, gives 61 .26 ounces 
 for the weight of as much water as is contained in the head, 
 upon one inch in depth, xV of which is 3.83 pounds; this 
 multiplied by the depth 21 inches, gives 80.43 pounds for 
 the value of 12 strokes ; and by proportion, 39^ (the number 
 made in a minute) will give 264.7 pounds, the weight of water 
 expended in a minute. 
 
 Now as 264.7 pounds of water may be considered as having 
 descended through a space of 15 inches in a minute, the 
 product of these two numbers 3970 will express potver 
 of the water to produce mechanical effects; which were as 
 follows : 
 
 The velocity of the wheel at the maximum, as appears 
 above, was 30 turns a minute ; which multiplied by nine 
 inches, the circumference of the cylinder, makes 270 inches ; 
 but as the scale was hung by a pulley and double line, the 
 weight was only raised half of this, viz. 135 inches. 
 
 lb. oz. 
 
 The weight in the scale at the maximum . . 8 — 
 
 The weight of the scale and pulley — 10 
 
 The counterweight, scale, and pulley .... — 12 
 
 Sum of the resistance . . 9 6 
 
 Or pounds . . 9.375 
 
 Now as 9.375 pounds is raised 135 inches, these two numbers 
 being multiplied together, the product is 1266, which ex- 
 presses the effect produced at a maximum ; so that the pro- 
 portion of the power to the effect is as 3970 : 1266, or as 
 10 : 3.18. 
 
 But though this is the greatest single effect producible 
 from the power mentioned, b^y the impulse of the water upon 
 
 f2 
 
THE OPEttATIVE MECHANIC 
 
 68 
 
 an undershot- wheel ; yet, as the whole power of the water is 
 not exhausted by it, this will not be the true ratio between 
 the poiver of the water, and the sum of all the effects pro- 
 ducible therefrom ; for, as the water must necessarily leave 
 the wheel with a velocity equal to the wheeFs circumference, 
 it is plain some part of the power of the water must remain 
 after quitting the wheel. 
 
 The velocity of the wheel at the maximum is 30 turns a 
 minute; and consequently its circumference moves at the 
 rate of 3.123 feet a second, which answers to a head of 1.82 
 inches; this being multiplied by the expense of water in a 
 minute, viz. 264.7 pounds produces 481 for the power 
 remainmg in the water after it has passed the wheel : this 
 being therefore deducted from the original power 3.9J0, 
 leaves 3.489, which is that part of the power spent in pro- 
 ducing the effect 1266; and, consequently, the part of the 
 power spent in producing the effect, is to the greatest 
 effect that it produces as 3489 : 1266 : : lO : 3.62, or as 
 
 11 to 4. 
 
 The velocity of the water striking the wheel has been 
 determined to be equal to 86 circumferences of the wheel per 
 minute, and the velocity of the wheel at the maximum to be 
 30 ; the velocity of the water will therefore be to that of the 
 wheel as 86 to 30, or as 10 to 3.5, or as 20 to 7» 
 
 The load at the maximum has been sh»wn to be equal to 
 nine pounds six ounces, and the wheel t;eased moving with 
 
 12 pounds in the scale ; to which if the weight of the scale 
 be added, viz. 10 ounces, the proportion will be nearly as 
 3 to 4 between the load at the maximum and that by 
 which the wheel is stopped. 
 
 It is somewhat remarkable, that though the velocity of the 
 wheel in relation to the water turns out greater than 4- of the 
 velocity of the water, yet the impulse of the water in the 
 case of a maximum is more than double of what is assigned 
 by theory ; that is, instead of 4 of the column, it is nearly 
 equal to the whole column. 
 
 It must be remembered, therefore, that, in the present 
 case, the wheel was not placed in an open river, where the 
 natural current, after it has communicated its impulse to the 
 float, has room on all sides to escape, as the theory supposes; 
 but in a conduit or race, to which the float is adapted, 
 the water cannot otherwise escape than by moving along 
 with the wheel. It is observable, that a wheel working in 
 this manner, so soon as the water meets the float, receives a 
 sudden check, and rises up against the float, like a wave against 
 
69 
 
 AND MACHINIST. 
 
 a fixed object; insomuch, that when a sheet of water is not 
 a quarter of an inch thick before it meets the float, yet this 
 ‘ sheet will act upon the whole surface of a float whose height 
 is three inches ; and, consequently, were the float no higher 
 than the thickness of the sheet of water, as the theory also 
 supposes, a great part of the force would have been lost by 
 the water dashing over the float. 
 
 Mr. Smeaton next proceeds to give tables of the velocities 
 of wheels with different heights of water ; and from the whole 
 deduces the following conclusions. 
 
 Maxim 1 . That the virtual or effective head of water, and 
 consequently its effluent velocity, being the same, the me- 
 chanical effect produced by a wheel actuated by this water 
 will be nearly in proportion to the quantity of water expended. 
 
 Note , — The virtual or effective head of any water which is 
 moving with a certain velocity, is that height from which a 
 heavy body must fall, in order to acquire the same velocity. 
 
 The height of the virtual head, therefore, may be easily 
 determined from the velocity of the water; for the heights 
 are as the square of the velocities, and the velocities, conse- 
 quently, as the square roots of the heights. Mr. Smeaton 
 observed the velocity of the effluent water in all his experi- 
 ments, and thence calculated the virtual head : he states, that 
 the virtual head bears no proportion to the real head or depth 
 of water; but that when either the aperture is greater, or 
 when the velocity of the water issuing therefrom less, they 
 approach nearer to a coincidence ; and consequently, in the 
 large openings of mills or sluices, where great quantities of 
 water are discharged from moderate heads, the actual head 
 of water, and the virtual head, as determined by theory from 
 the velocity, will nearly agree. 
 
 For example of the application of his first maxim. Suppose 
 a mill driven by a fall of water whose virtual head is five feet, 
 and which discharged 550 cubic feet of water per minute, 
 and that it is capable of grinding four bushels of wheat in 
 an hour. Now another mill, having the same virtual head, 
 but which discharges 1100 cubic feet of water per minute, 
 will grind eight bushels of corn in ail hour. 
 
 Maxim 2. That the expense of water being the same, the 
 effect produced by an undershot^wheel will be nearly in pro- 
 portion to the height of the virtual or effective head. This is 
 proved in the preceding example. 
 
 Maxim 3. That the quantity of water expended being the 
 same, the effect will be nearly as the square of the velocity of 
 the water; that is, if a mill driven by a certain quantity of 
 
70 the operative mechanic 
 
 water^ moving with the velocity of 18 feet per second, is 
 capable of grinding four bushels of corn in an hour, another 
 mill, driven by the same quantity of water, but moving with 
 the velocity of 22 J feet per second, will grind nearly seven 
 bushels of corn in an hour; because the square of 18 is 324, 
 and the square of 22 J is 506 J. Now, say, as 324 is to 4 
 bushels, so is 506 J to 6^ bushels; that is as 4 to 6^. 
 
 Maxim 4. The aperture through which the water issues 
 being the same, the effect will be nearly as the cube of the 
 velocity of the water issuing; that is, if a mill driven by water 
 rushing through a certain aperture with the velocity of 18 feet 
 per second will grind four bushels of corn in an hour, another 
 mill, driven by water moving through the same aperture, but 
 with the velocity of 22^ feet per second, will grind 51 bushels ; 
 for the cube of 18 is 5832, and the cube of 22J is 11390|; 
 then as 5832 is to 4, so is 11390| to 7i- 
 
 Maxim 5. The proportions between the power of the 
 water expended, and the effect produced by the wheel, were 
 3 to 1. Upon comparing several experiments, Mr. Smea- 
 ton fixed the proportions between them for large works; 
 that is, it the weight of the water which is expended in any 
 given time be multiplied by the height of the fall, and if the 
 weight raised be also multiplied by the height through which 
 it is raised, the first of these two products will be three times 
 that of the second. 
 
 Maxim 6. The best general proportions of velocities be- 
 tween the water and the floats of the wheels will be that of 
 5 to 2; for instance, if the water when it strikes the 
 wheel moves with a velocity of 18 feet per second, the wheel 
 must be so loaded that its float-boards will move with a 
 velocity of 7-2 feet per second, and the wheel will then 
 derive the greatest power from the water, because as 5 to 
 18, so is 2 to 7*2. 
 
 Maxim 7. There is no certain ratio between the load that 
 the wheel will carry when producing its maximum of effect, 
 and the load that will totally stop it; but it approaches 
 nearest to the ratio of 4 to 3, whenever the power ex- 
 erted by the wheel is greatest, whether it arise from an 
 increase of the velocity, or from an increased quantity of 
 water; and this proportion seems to be the most applicable 
 to large works. But when we know the effect which a wheel 
 ought to produce, and the velocity it ought to move with 
 whilst producing that effect, the exact knowledge of the 
 greatest load it will bear is of very little consequence in 
 practice. 
 
AND MACHINIST. 
 
 Maxim 8. The load that the wheel ought to have, in order 
 to work to the most advantage, can be always assigned thus : 
 ascertain the power of the whole body of water, by multiply- 
 ing the weight of the water expended in a minute by the 
 height of the fall ; take one-third of the product, and it gives 
 the effect of power which the wheel ought to produce : to 
 find the load, we must divide this product by the velocity 
 which the wheel should have, and that, as We have before 
 settled, should be two-fifths of the velocity with which the 
 water moves when it strikes the wheel. 
 
 In the application of these principles the first thing to 
 be done in a situation where an undershot-wheel is intended 
 to be fixed, is to consider whether the water can rim 
 off clear from the wheel, ^ so as to have no back-water to 
 impede its motion; and whether the fall which can be 
 obtained by constructing a proper dam to pen up the 
 water, and sluice for it to pass through, will cause it to 
 strike the float-boards of the wheel with sufficient velocity 
 to impel them forcibly forwards; and also, whether the 
 quantity of the supply will be sufficient to keep a wheel 
 at work for a certain number of hours each day. 
 
 When we have ascertained the height of the fall of water, 
 that is the height of the surface above the centre of the 
 opening of the sluice, we must find what will be the con- 
 tinual velocity of the water issuing from such opening. 
 
 In SQiue cases, we have the velocity of the water given 
 when it issues from the opening of the sluice, and we 
 then require to know what height of column will pro- 
 duce that velocity. These two things we may find by a 
 single rule, and an easy arithmetical operation, which is as 
 follows : 
 
 1st. The perpendicular height of the fall of water being 
 given in feet and decimals of feet, the velocity that the water 
 will acquire per second, expressed in feet and decimals, may 
 be, found by the following rule : 
 
 Multiply the constant number 64.2882 by the given 
 height, and the square root of the product is the velocity 
 required. 
 
 ILxample 1. If the height is two feet, the velocity will be 
 found 11.34 feet per second. 
 
 Example 2. If the height is 16.0913 feet, the velocity 
 will be 32.1826 feet per second. 
 
 Example 3. If the height is 60 feet, the velocity will be 
 56.68 feet per second. 
 
 Note . — The velocities thus obtained will be only the thco- 
 
THE OPERATIVE MECHANIC 
 
 72 
 
 retie velocity ; that is, the velocity any body would acquire 
 by falling through such height in vacuo; the velocity in 
 reality will be less, generally six or seven tenths. 
 
 The uniform velocity of a fluid being given, expressed in 
 feet and decimals of feet per second, the height of the column 
 or fall to produce such a velocity may be found by the 
 following rule : 
 
 Multiply the given velocity into itself, and divide the 
 product by 64.2882 ; the quotient will be the height required, 
 expressed in feet and decimals. 
 
 J^xample I . If the velocity given is three feet per second, 
 the height will be 0.139 of a foot. 
 
 Example 2. If the velocity given is 32.1826 feet per 
 second, the height will be found 16.0913 feet. 
 
 Example 3. Let the velocity be 100 feet per second, 
 the height will be 155.694 feet. 
 
 The knowledge of the foregoing particulars is absolutely 
 necessary for constructing an undershot water-wheel; but the 
 most advantageous method of setting it to work, and to find 
 out the utmost it could perform, would be very difficult, if 
 we were not furnished with the maximum which Mr. Smeaton 
 settled, by showing, that an undershot water-wheel will act 
 to the greatest advantage when the velocity of its float-boards 
 is equal to two-fifths of four-tenth parts of that of the water 
 which gives it motion. 
 
 Lambert’s water-wheel. 
 
 In 1819, Mr. Lambert, of Prince’s-street, Leicester-square, 
 obtained a patent for an improvement in the water-wheel, 
 which he thus describes; 
 
 “ My improved water-wheel, as shown in figs. 85, 86, and 
 87, represents the paddles standing in a vertical position to 
 the surface of the water through which they are to pass, and 
 in whatever situation or direction the wheel either rests or 
 moves, the paddles preserve the same vertical position. 
 The great advantage derived from the paddles of a water- 
 wheel entering and quitting the water through which such 
 wheel revolves in a perpendicular direction, has long been 
 admitted to be a most important and desirable measure in 
 that class of water-wheels known and called by engineers 
 undershot- wheels, either for water-mills or for navigable pur 
 poses. The benefit of working the paddles of such wheels 
 in a vertical position is not only the superior hold and pressure 
 which the water takes on the paddles or floats of such wheels. 
 hiii the very little back-water which they create on leaving 
 
AND MACHINIST. 
 
 73 
 
 it. The principle of this improvement is to make the lower 
 paddles recede from the centre of the axle and to the arms 
 to which they are attached, while the upper paddies proceed 
 I to the centre of the axle in equal distances as the others 
 t recede; and in the rotation of the wheel, every paddle passes 
 1 through the various evolutions and positions to which every 
 h revolution of the wheel subjects each paddle. The lower 
 I paddles describe a greater radius of a circle than the upper 
 
 L paddles, and thereby travel at an increased velocity, or rather 
 
 they pass at their extreme points through a greater space in 
 the same period of time ; this effect renders the lower half of 
 ^ the wheel heavier than the upper, by the eccentric position 
 of the paddles, and the flat ring of iron to which they are 
 attached, and it also increases the speed of any navigable 
 I body through the water to which such wheels are applied. 
 
 Figs. 85, 86, and SJ, are views of my improved wheel with 
 one paddle, as in fig. 85, at its greatest depth in the water; 
 
 I B, B, B, B, is one of the iron arm frames to which one end of 
 
 the paddles C, C, C, C, C, C, are attached by the joint-pins 
 D, D, D, D, D, D, to the arm frames B, B, B, B. EE is the 
 flat iron ring or eccentric circle, to which the other ends of 
 the paddles are attached by similar joint-pins F,F, F, F, F, F. 
 G G, are the iron guard or guide-rollers, a section of one of 
 which is shown at fig. 88, which may either revolve on fixed 
 axles, or these rollers may be fixed on revolving axles, which- 
 ever is most convenient. The object of these rollers is, to 
 keep the iron circle E E in its proper situation, which is an 
 equal distant position from the centre of the wheel- shaft in a 
 longitudinal direction, and eccentric in a vertical position to the 
 shaft A. These rollers must be placed apart from each other, 
 a distance exactly equal to the diameter of the iron circle 
 EE, consequently the rollers GG must be placed in a line 
 through the centre of the circle EE and which will allow 
 this circle to rub and give motion to the rollers G G, at the 
 speed it revolves. The circle E E, forms an eccentric course, 
 while it rubs on every part of its periphery against the rollers 
 G G. This circle E E may be formed with teeth like the rim 
 of a cog-wheel, and in that case the rollers G G may either 
 one or both of them be formed into spur pinions to fit the 
 teeth of the circle E E, which would be a quick and simple 
 mode for my improved water-wheel to work machinery. I 
 sometimes use two flat, hardened steel springs, as shown in 
 fig. 89, instead of the rollers G G, to keep the circle E E in 
 its proper place ; and in certain situations they will be found 
 
74 THE OPERATIVE MECHANIC 
 
 to answer very well. Great care must be taken to make the 
 joint pin-holes in the iron frames B, B, B, B, exactly an equal 
 distance apart from each other; and it must also be observed 
 in piercing or drilling the joint pin-holes in the circle EE^ 
 that they correspond with the holes made in the arm frames 
 B, B^ B^ B. It will be always advisable to drill both the 
 arm frames, B, B, B, B, and the circle E E, together, that the 
 joint pin-holes in all three may correspond exactly with each 
 other, and particularly from the centre of each. The joint 
 pin-holes, in the paddle-plates or floats, should also be made 
 to correspond with each other; and it is the distance of the 
 holes from D to F in the paddles C C, as shown at fig. 90, 
 which determine the eccentricity of the course of the iron 
 ring E E ; and it is by connecting these paddles at D to the 
 arm frames E, B, B, B, and at F to the ring E E, which in 
 the rotation of the whole by the axle A, and by keeping the 
 circle E E in its proper situation as before described, either 
 by the rollers G G, or when the springs H H are substituted 
 for the rollers, that the paddles always preserve a vertical 
 position to the surface of the water, and which cause the 
 upper paddles to approach, whilst the lower paddles recede 
 from the centre of the axle A. Fig. 86 represents a view of 
 the wheel combined with all the paddles connected to both 
 frames of the wheel, with the iron ring or circle E E placed 
 in the middle of the frames and between the sides of the 
 paddles, with the joint-pins in their proper places, with the 
 two lower paddles at their most extended distance from the 
 centre of axle A, whilst the two upper paddles are brought 
 to their nearest situation to that axle; the joint-pins must 
 either have nuts and screws, or other proper fastenings, to 
 keep them in their several places, or split keys, the latter of 
 which I decidedly prefer. The axle A must be properly 
 placed and secured in the iron frames B, B, B, B, in any of 
 the ordinary modes which an experienced and skilful workman 
 w'ill adopt. The number of sets of'paddles or floats for any 
 one wheel must be determined according to the magnitude 
 and duty of such wheel; it is the general construction and 
 combination as described, which constitute my improved 
 wheel, and not the number of the paddles or floats, or their 
 magnitude. I should, however, never recommend less than 
 six sets of paddles or floats to be combined in any wheel 
 made on the plan of my improved wheel, although I am aware 
 it would act with a less number, but not so advantageously. 
 The same letters in figs. 85, 86, and 87? represent the same 
 
WATJEJR WMJEIEJLS 
 
 From 85 to 93 ♦ 
 
 8.y 
 
 86 
 
 n.8 
 
 Fedt-iStockL^ se 35^SiranJ 
 
AND MACHINIST. 
 
 75 
 
 parts in either of these figures, and as far as any of the similar 
 parts are shown in figs. 88 , 89, and 90, the letters and 
 characters also distinguish them. 
 
 THE OVERSHOT-WHEEL, 
 
 This 'wheel consists of a frame of open buckets, placed 
 round the rim of a* vertical wheel, to receive the water 
 from a spout placed over it, so that the buckets on the 
 one side shall be always loaded, while those on the opposite 
 side are empty. The loaded side will of course descend, 
 and the wheel in its revolution will bring the empty buckets 
 under the spout, to be in their turn filled with water. 
 
 The principal thing to be attended to in the construction 
 of this wheel is to have the buckets of such a form as will 
 retain the water along the greatest circumference of the 
 wheel : and as this is a thing not easily to be accomplished, 
 numerous contrivances have been resorted to by mill-wrights 
 to determine the best possible form. 
 
 Fig. 91 is the outline of a wheel having 40 buckets. The 
 ring of board contained between the concentric circles Q D S 
 and PA R, making the ends of the buckets, is called the 
 shrouding, and Q P the depth of shrouding. The inner circle 
 P A R is called the sole of the wheel, and usually consists of 
 boards nailed to strong wooden rings of compass timber of 
 considerable scantling, firmly united with the arms or radii. 
 The partitions, which determine the form of the buckets, 
 consist of three different planes or boards, A B, B C, CD, 
 which are variously named by different artists. We have 
 heard them called the start or shoulder, the arm, and the 
 wrest : (probably for wrist, on account of a resemblance of 
 the whole line to the human arm:) B is also called the 
 elbow. 
 
 Fig. 92 represents a small portion of the same bucketing 
 on a larger scale, that the proportion of the parts may be 
 more distinctly seen. AG the sole of one bucket is made 
 about ^ more than the depth G H of the shrouding. The 
 start ^ A B is 4 of A I. The plane B C is so inclined to A B 
 that it would pass through H 3 but it is made to terminate in 
 C, in^ such a manner that F C is l^ths of G H or A I. Then 
 C D is so placed that H D is about ^th of I H. 
 
 By this construction it follows that the area F A B C is 
 very nearly equal to D AB C; so that the water which will 
 fill the space F A B C will all be contained in the bucket 
 when it shall come into such a position that A D is a hori- 
 zontal line; and the line AB will then make an angle of 
 
THE OrERATlVE MECHANIC 
 
 70 
 
 35° with the vertical, or the bucket will be 35° from the 
 perpendicular, passing through the axis of motion. If the 
 bucket descend so much lower that one half of the water runs 
 out, the line A B will make an angle of 25° or 24° nearly 
 with the vertical. Therefore the wheel, filled to the degree 
 now mentioned, will begin to lose water at about -^th of the 
 diameter from the bottom, and half of the vjater will be 
 discharged from the lowest bucket, about -rVth of the diame- 
 ter further down. Had a greater proportion of the buckets 
 been filled with water when they were under the spout, the 
 discharge would have begun at a greater height from the 
 bottom, and we should lose a greater portion of the whole 
 fall of water. The loss by the present construction is less 
 than Tuth, (supposing the water to be delivered into the wheel 
 at the very top,) and may be estimated at about i^Tth; for the 
 loss is the versed sine of the angle which the radius of the 
 bucket make with the vertical. The versed sine of 35® is 
 nearly i^th of the radius, being 0.18085, or Thrth of the dia- 
 meter. It is evident, that if only ^ of this water were supplied 
 to each bucket as it passes the spout, it would have been 
 retained for 10° more of a revolution, and the loss of fall 
 W’ould have only been about -rTth. 
 
 These observations serve to show in general, that an 
 advantage is gained by having the buckets so capacious that 
 the quantity of water which each can receive as it passes the 
 spout may not nearly fill it. This may be accomplished by 
 making them of a sufficient length, that is, by making the 
 wheel sufficiently broad between the two shroudings. 
 
 Mr. Robert Burns, of Cartside, in Renfrewshire, has made 
 what appeared to be a very considerable improvement in the 
 construction of the bucket. The principle of this improve- 
 ment consisted in dividing the bucket by a partition of such 
 a height, that the inner and outer portions of the bucket on 
 each side were nearly of equal capacity. See fig. 93. The 
 bucket consisted of a start A B, an arm B C, and a wrest C D, 
 concentric with the rim, and was divided by the partition LM, 
 concentric with the sole and rim. If these buckets be filled 
 one-third, they will retain the whole of the water at 18®, and 
 the half at 11°, from the bottom. These advantages how- 
 ever were found to be counterbalanced by disadvantages ; and 
 Mr. Burns did never, we believe, put the construction in 
 practice. 
 
 The velocity of an overshot- wheel is a matter of very great 
 nicety; and authors, both speculative and practical, have 
 arrived at very different conclusions respecting it. M. Be^ 
 
AND MACHINIST. 
 
 // 
 
 lidol very strangely maintains, that there is a certain velocity 
 related to that obtainable by the whole fall, which will 
 procure to an overshot-wheel the greatest performance. 
 Desaguliers, Smeaton, Lambert, De Parcieux, and others, 
 maintain, that there is no such relation, and that the perform- 
 ance of an overshot-wheel will be the greater, as it moves 
 more slowly by an increase of its load of work. Belidor 
 again states, that the active power of water lying in a bucket- 
 w'heel of any diameter is equal to the impulse of the same 
 water on the floats of an undershot-wheel, when the water 
 issues from a sluice in the bottom of the dam. The other 
 writers whom we have named assert, that the energy of an 
 undershot- wheel is but one half of that of an overshot, actuated 
 by the same quantity of water falling from the same height. 
 The most generally received opinion is, that the overshot- 
 wheel does the more work, as it moves slower 3 and the 
 following is the reasoning adduced to prove it. Suppose 
 that a wheel has 30 buckets, and that six cubic feet of water 
 are delivered in a second on the top of the wheel, and dis- 
 charged, without any loss by the way, at a certain height 
 from the bottom of the wheel. Let this be the case, whatever 
 is the rate of the wheel’s motion, the buckets being of a 
 sufficient capacity to hold all the water which falls into them. 
 Suppose this w’heel employed to raise a weight of any kind, 
 water for instance, in a chain of 30 buckets, to the same 
 altitude and with the same velocity. Suppose, further, that 
 when the load on the rising side of the machine is one half 
 of that on the wheel, the wheel makes four revolutions in a 
 minute, or one turn in 15 seconds. During this time 90 
 cubic feet of water will have flowed into the 30 buckets, and 
 each have received three cubic feet. In that case each of the 
 rising buckets contains IJ feet; and 45 cubic feet are deli- 
 vered into the upper cistern during one turn of the w^heel, 
 and 180 cubic feet in one minute. 
 
 Now, suppose the machine so loaded, by making the rising 
 buckets more capacious, that it makes only two turns in a 
 minute, or one turn in 30 seconds; then each descending 
 bucket must contain six cubic feet of water. If each bucket 
 on the rising side contained three cubic feet, the motion of the 
 machme would be the same as before. This is a point none 
 will controvert. When two pounds are suspended to one 
 end of a string which passes over a pulley, and one pound to 
 the other end, the velocity of descent of the two pounds will 
 be the same with that of a four pound weight, which is 
 employed in the same manner to draw up two pounds. Our 
 
THE OPERATIVE MECHANIC 
 
 78 
 
 machine would therefore continue to make four turns in a 
 minute, and woidd deliver 90 cubic feet during each turn, 
 and 360 in a minute. But, by supposition, it is making only 
 two turns in a minute ; which must proceed from a greater 
 load than three cubic feet of rising water in each rising 
 bucket. The machine must, therefore, be raising more than 
 90 feet of water during one turn of the wheel, and more than 
 180 in a minute. 
 
 Thus it appears that if the machine is turning twice as 
 slow as before, there is more than twice the former quantity 
 in the rising buckets ; and more will be raised in a minute Dy 
 the same expenditure of power. In like manner, if the 
 machine go three times as slow, there must be more than 
 three times the former quantity in the rising buckets, and 
 more work will be done. 
 
 But further we may assert, that the more we retard the 
 machine to a certain practical extent, by loading it with more 
 work of a similar kind, the greater will be its performance ; 
 and the truth of the assertion may be thus demonstrated. 
 Let us call the first quantity of water in the rising bucket, 
 Q ; the water raised by four turns in a minute will be 4 x 30 
 X Q = 120 Q. The quantity in this bucket, when the ma- 
 chine goes twice as slow, has been shown to be greater than 
 2Q; call it 2 Q + x; the water raised by two turns in a 
 minute will then be 2 x 30 x (2 Q + ^) = 120 + 60 x. 
 Suppose next, the machine to go four times as slow, making 
 but one turn in a minute ; the rising bucket must now 
 contain more than twice the quantity 2 Q + a’, or more than 
 4 Q 4- 2 call it4Q + 2x + y. The work done by one 
 turn in a minute will now be 30 x (4Q -h 2x + y) =120 
 Q + 60 ^ + 30 ?/. By such an induction of the work accom- 
 plished, with any rates of motion we choose, it is evident 
 that the performance of the machine increases with every 
 diminution of its velocity tliat is produced by the mere addi- 
 tion of a similar load of work, or that it does the more work 
 the slower it goes. This, however, is abstracting from the 
 effects of the friction upon the gudgeons of the wheel, a 
 cause of resistance which increases with the load, though 
 not in the same ratio. 
 
 We have also supposed the machine to be in its state of 
 ])ermanent uniform motion. If we consider it only in the 
 beginning of its motion, the residt is still more in favour of 
 slow motion : for, at the first action of the moving power, the 
 inertia of the machine itself consumes part of it, and it acquires 
 its permanent velocity by degrees, during which the resist- 
 
AND MACHINI.ST. 
 
 79 
 
 ances arising from the work^ friction^ &c., increase, till they 
 exactly balance the pressure of the water ; and after this the 
 machine no longer accelerates. Now, the greater the power 
 and the resistance arising from the work are, in proportion 
 to the inertia of the machine, the sooner, it is obvious, will it 
 arrive at its state of permanent velocity. 
 
 The preceding discussion only demonstrates in general the 
 advantage of slow motion j but does not point out in any 
 degree the relation between the rate of motion and the work 
 performed, nor even the principles on which it depends. But 
 this is not necessary for the improvement of practical me- 
 chanics. It is, however, manifest, that there is not, in the 
 nature of things, a maximum of performance attached to any 
 particular rate of motion which should, on that account, be 
 preferred. All, therefore, that we have to do, is to load the 
 machine, and thus to diminish its speed, unless other pli3^sical 
 circumstances throw obstacles in the way : for there are such 
 obstacles, as in all machines there are certain inequalities of 
 action that are unavoidable. In the action of a Avheel and 
 pinion, though made with the utmost judgment and care, 
 there are such inequalities. These increase by the changes 
 of form occasioned by the wearing of the machine ; and much 
 greater irregularities arise from the subsultory motions of 
 cranks, stampers, and other parts which move unequally or 
 reciprocally. A machine may be so loaded as just to be in 
 equilibrio with its work, in the favourable position of its 
 parts : and when this changes into one less favourable, the 
 machine may stop, or, at all events, hobble and work un- 
 equally. The rubbing parts thus bear long on each other, 
 with enormous pressures, cut deep into each other, and 
 increase friction : therefore such slow motions should be 
 avoided. A little more velocity enables the machine to over- 
 come those increased resistances by its inertia, or the great 
 quantity of motion inherent in it. Great machines possess 
 this advantage in a superior degree, and, consequently, will 
 work steadily with a smaller velocity. 
 
 Mr. Smeaton, in his Experimental Inquiry, previous to 
 examining into the power and application of water, when 
 acting by its gravity on over shot-wheels, says, In reasoning 
 without experiment, one might be led to imagine, that how- 
 ever different the mode of application is, yet that whenever 
 the same quantity of water descends through the same per- 
 pendicular space, that the natural effective power would be 
 equal, supposing the machinery free from friction, equally 
 calculated to receive the full effect of the power, and to make 
 
80 
 
 THE OPERATIVE MECHANIC 
 
 the most of it: for if we suppose the height of a column of 
 water to be 30 inches, and resting upon a base or aperture 
 one inch square, every cubic inch of water that departs there-- 
 from will acquire the same velocity or momentum, from the 
 uniform pressure of 30 inches above it, that one cubic inch 
 let fall from the top will acquire in falling down to the level 
 of the aperture : one would therefore suppose, that a cubic 
 inch of water, let fall through a space of 30 inches, and there 
 impinging upon another body, would be capable of producing 
 an equal effect by collision, as if the same cubic inch had 
 descended through the same space with a slower motion, and 
 produced its effects gradually. But however conclusive this 
 reasoning may seem, it will appear, in the course of the 
 following deductions, that the effect of the gravity of descend- 
 ing bodies is very different from the effect of stroke of such 
 as are non-elastic, though generated by an equal mechanical 
 power.^’ 
 
 When Mr. Smeaton had finished his experiments on under- 
 shot mills, he reduced the number of floats on the wheel, 
 which were originally 24, to 12; which caused a diminution in 
 the effect, on account of a greater quantity of water escaping 
 between the floats and the floor : but a circular sweep being 
 adapted thereto, of such a length, that one float entered the 
 curve before the preceding one quitted it, the effect came so 
 near that of the former, as not to give any hopes of advanc- 
 ing it by increasing the number of floats beyond 24 in this^ 
 particular wheel. 
 
 In these experiments the head was six inches, and the 
 lieight of the wheel 24 inches, so that the whole descent was 
 30 inches : the quantity of water expended in a minute was 
 96^ pounds, which, multiplied by 30 inches, gives the power 
 = 2900. After making the proper calculations, the effect was 
 computed at 1914; the ratio therefore of Xhe power and effect 
 will be as 2900 : 1914, or as 10 : 6.6, or as 3 to 2 nearly^ 
 But if we compute the power from the height of the wheel 
 only, we shall have 96f pounds, multiplied by 24 inches 
 = 2320 for the power, and this will be to the effect as 
 2320 : 1914, or as 10 : 82, or as 5 to 4 nearly. 
 
 From another set of experiments the following conclusions 
 were deduced: 
 
 1. The effective power of the water must be reckoned 
 upon the whole descent, because it must be raised that 
 height in order to produce the same effect a second time 
 The ratios between the powers so estimated, and the effects 
 at the maximum, differ nearly from that of 10 to to that 
 
AND MACHINIST, 
 
 81 
 
 of 10 to 5.2, that is nearly from 4.3 to 4.2. In those expe- 
 riments where the heads of water and quantities expended 
 are least, the proportion is nearly as 4 to 3 ; but where the 
 heads and quantities are greatest, it approaches nearer to 
 that of 4 to 2 ; and by a medium of the whole, the ratio is 
 that of 3 to 2 nearly. Hence it appears, that the effect of 
 overshot-wheels is nearly double to that of the undershot, 
 and, by consequence, that non- elastic bodies, when acting 
 by their impulse or collision, comniunicate only a part of 
 their original power, the remainder being spent in changing 
 their figure in consequence of the stroke. The ultimate 
 conclusion is, that the effects, as well as the powers, are as 
 the quantities of water and perpendicular heights multiplied 
 together respectively. 
 
 2. By increasing the head from 3 to 11 inches, that is, the 
 whole descent from 27 inches to 35, or in the ratio of 
 7 to 9 nearly, the effect is advanced no more than in the 
 ratio of 8.1 to 8.4, that is, as 7 to 7*26; and consequently 
 the increase of effect is not one- seventh of the increase of 
 perpendicular height. Hence it follows, that the higher the 
 wheel is in proportion to the whole descent, the greater will 
 be the effect ; because it depends less upon the impulse of 
 the head, and more upon the gravity of the water in the 
 buckets : and if we consider how obliquely the water issuing 
 from the head must strike the buckets, we shall not be at a 
 loss to account for the little advantage that arises from the 
 impulse thereof, and shall immediately see of how little con- 
 sequence this impulse is to the effect of an overshot- wheel. 
 This, however, like other things, is subject to limitation, for 
 it is desirable that the water should have somewhat greater 
 velocity than the circumference of the wheel, in coming 
 thereon ; otherwise the wheel will not only be retarded by 
 the buckets striking the water, but a portion of the power 
 will be lost by the water dashing over the buckets. 
 
 3. To determine the velocity which the circumference of 
 the wheel ought to have in order to produce the greatest 
 effect, Mr. Smeaton observes, that the slower a body descends, 
 the greater will be the portion of tht action of gravity appli- 
 cable to the producing a mechanical effect, and, in consequence, 
 the greater wdll be the effect. If a stream of water falls into 
 the bucket of an overshot-wheel, it is there retained till 
 the wheel by moving round discharges it, and consequently 
 the slower the wheel moves, the more water each bucket 
 will receive : so that what is lost in speed, is gained by the 
 pressure of a greater quantity of water acting in the buckets 
 
 G 
 
82 
 
 THE OPERATIVE MECHANIC 
 
 at once. From the experiments, however, it appeared, that 
 when the wheel made about 20 turns in a minute, the effect 
 was near upon the greatest. When it made 30 turns, the 
 effect was diminished about V^^th part; and that when it 
 made 40, it was diminished about J ; when it made less than 
 18j, its motion was irregular; and when it was loaded so as 
 not to admit its making 18 turns, the wheel was overpowered 
 by its load. It is an advantage in practice, that the velocity 
 of the wheel should not be diminished further than will pro- 
 cure some solid advantage in point of power, because ccEteris 
 paribus, as the motion is slower, the buckets must be made 
 larger, and the wheel being more loaded with water, the 
 stress upon every part of the work will be increased in pro- 
 portion. The best velocity for practice, therefore, will be 
 such, as when the wheel made 30 turns in a minute, that is, _^ 
 wdien the velocity of the circumference is a little more thaiiB 
 three feet in a second. Experience confirms that this velo^* 
 city of three feet in a second is applicable to the highest— 
 overshot- wheels, as well as the lowest ; and all other parts ofjji 
 the work being properly adapted thereto, wall produce very"*^ 
 nearly the greatest effect possible ; it is also determined by , 
 experience, that high wheels may deviate further from this 
 rule, before they will lose their power, by a given aliquot^; 
 part of the whole, than low ones can be admitted to do;jf 
 For a wheel of 24 feet high may move at the rate of six feet? 
 per second without losing any part of its power; and, on^ 
 the other hand, the author had seen a wheel of 33 feet high' . 
 that moved very steadily and well, with a velocity but little; 
 exceeding two feet. The reason of the superior velocity of 
 the 24 feet wheel seems to have been owing to the small* 
 proportion that the head, requisite to give the water the 
 proper velocity of the wheel, bears to the whole height. 
 
 4. The maximum load for an overshot-wheel, is that which^ 
 
 reduces the circumferences of the wheel to its proper velocity;' ^ 
 which will be known by dividing the effect it ought to pro- 
 duce in a given time, by the space intended to be described' jj 
 by the circumference of the wheel in the same time; the^ j 
 quotient will be the resistance overcome at the circumference^ | 
 of the wheel, and is equal to the load required, the friction^ 1 
 and resistance of the machinery included. * j 
 
 5. The greatest velocity of which the circumference of an'^ I 
 overshot- wheel is capable, depends jointly upon the diameter ' j 
 of the height of the wheel, and the velocity of falling bodies ; ' j 
 for it is plain that the velocity of the circumference can' j 
 never be greater than to describe a semi-circumference . 
 
AND MACHINIST. 
 
 83 
 
 while a body let fall from the top of the wheel will descend 
 through its diameter; nor even quite so great^ as a body 
 descending through the same perpendicular space cannot 
 perform the same in so small a time when passing through a 
 semi-circle as would be done in a perpendicular line. Thus, 
 if a wheel is 16 feet one inch in diameter, a body will fall 
 through it in one second: this wheel therefore can never 
 arrive at a velocity equal to the making one turn in two 
 seconds; but, in reality, an overshot-wheel can never come 
 near this velocity ; for when it acquires a certain speed, the 
 greatest part of the water is prevented from entering the 
 buckets, and the rest, at a certain point of its descent, is 
 thrown out again by the centrifugal force. As these circum- 
 stances depend chiefly upon the form of the buckets, the 
 utmost velocity of overshot-wheels caminot be generally 
 determined; and, indeed, it is the less necessary in practice, 
 as it is in this circumstance incapable of producing any 
 mechanical effect. 
 
 6. The greatest load an overshot-wheel will overcome, 
 considered abstractedly, is unlimited or infinite; for as the 
 buckets may be of any given capacity, the more the wheel is 
 loaded, the slow^er it turns, but the slower it turns, the more 
 will the buckets be filled with water; and, consequently, 
 though the diameter of the wheel and quantity of water 
 expended are both limited, yet no resistance can be assigned, 
 which it is not able to overcome ; but in practice we ahvays 
 meet with something that prevents our getting into infinitesi- 
 mals. For when we really go to work to build a wheel, the 
 buckets must necessarily be of some given capacity, and 
 consequently such a resistance will stop the wheel, as it is 
 equal to the effort of all the buckets in one semi-circum- 
 ference filled with water. The structure of the buckets 
 being given, the quantity of this efibrt may be assigned, but 
 is not of much consequence in practice, as in this case also 
 the wheel loses its power ; for though here is the exertion 
 of gravity upon a given quantity of water, yet being pre- 
 vented by a counterbalance from moving, is capable of 
 producing no mechanical effect, according to our definition. 
 But, in reality, an overshot-wheel generally ceases to be 
 useful before it is loaded to that pitch; for when it meets 
 with such a resistance as to diminish its velocity to a certain 
 degree, its motion becomes irregular ; yet this never happens 
 till the velocity of the circumference is less than two feet per 
 second, where the resistance is equable. 
 
 g2 
 
84 
 
 THE OPERATIVE MECHANIC 
 
 The reader having now become acquainted with the valu- 
 able course of experiments made by Mr. Smeaton^ we shall 
 next offer to his notice a few remarks upon the best mode of 
 delivering water upon an overshot-wheel. 
 
 In wheels of this construction^ it has been^ and still is, the 
 common practice, to allow the water to flow into the buckets 
 at the highest point of the wheel ; but this system is deci- 
 dedly bad ) for the centre of gravity of the upper bucket is 
 direct over the axle of the wheel, and, consequently, any 
 water poured into that bucket will, instead of creating a rota- 
 tory motion, cause a greater pressure upon the pivots of the 
 axle. The greatest advantage would be obtained by causing 
 the water to fall upon the wheel, at an angle of 42J or 
 45 degrees, as then the power of the wheel will be aug- 
 mented by the increased leverage. In constructing wheels 
 upon this principle, however, great care must be taken to 
 allow a sufficiency of room in buckets for the escape of air, 
 otherwise the wheel will not act. The same observation is 
 also applicable to breast- wheels ; for we were once present, 
 and witnessed an instance of this kind, at the first starting 
 of a breast-wheel, in which the millwright, in order to ob- 
 tain the greatest possible effect, had made the back-boards 
 to fit so tight that no water or air could escape ; the conse- 
 quence of which was, the necessity of reducing the whole of 
 the back-boards, to allow air enough to escape for the water 
 to act freely upon the floats. 
 
 burn’s overshot-wheel without a shaft. 
 
 This ingenious machine was invented and erected by the 
 late Mr. Burns, whose mechanical ingenuity we have already 
 had occasion to admire. It is represented in two different 
 sections, in figs. 95 and 96, and forms a large hollow cylinder 
 by its buckets and sole, without having any shaft or axle-tree. 
 
 This wheel is 12^ feet diameter, and seven feet broad over 
 all, and has 28 buckets. The gudgeon is 6 inches diameter, 
 by 9 inches long. The flaunch is 1 J inch thick at the ex- 
 treme points. The arms are of redwood fir, 6 inches square; 
 one piece making two arms in length, where they cross one 
 another at the wheel’s centre, 1 J inch of the wood remaining 
 in each, connecting the two opposite arms as one piece. The 
 wheels was made by first fitting the gudgeon into a large 
 piece of hard wood, with the flaunch parallel to the horizon, 
 and in that position the arms and rings were trained and 
 
AND MACHINIST. 
 
 85 
 
 bound fast to it. All the grooves for starts or raisers^ and 
 buckets, were cut out before it was remov ed ; first one piece 
 was bolted to the flaunch at a a, and so of the others, leaving 
 the distant openings for the cross bars that reach between 
 each arm and its opposite arm. These bars, or pieces, were 
 only 4 inches square, and were of good beech wood, turned 
 round in the body. They were 10 inches square at each end, 
 in which was fitted a strong nut for a bolt, 1 j inch thick, to 
 go through Z>, and connect the two sides together. 
 
 After the arms were trained and fixed right upon the gijd- 
 geons, the innermost ring was completed ; the tenons were 
 trained on the arms first, and the rings 4^ inches thick and 
 8 inches deep, put on by keys driven into the mortice. The 
 remaining tenons were then reduced from 1| to 1 inch thick, and 
 the outermost ring, only 3 inches thick by 6 inches deep, was 
 firmly wedged thereon, and bound fast at the other ends by three 
 strong wooden pins, as at C C ; to the lower ring, the outside 
 of the uppermost and undermost rings are flush, all the addi- 
 tional thickness of the lower ring projecting inside the buckets.' 
 
 Some difficulty was found in laying the water properly 
 into the buckets of this wheel, owing to the narrowness of 
 the mouths of the buckets, by the high start or raiser, which 
 was remedied by adopting the following plan. 
 
 4'he openings in the bottom of the troughing should be of 
 iron, and so distant from each other that the water from 
 them is thrown into two separate buckets. The iron curved 
 parts should also be movable, to adjust the openings to the 
 quantity of water necessary for the wheel. Unless the head 
 of water is 12 or 14 inches above these openings, it will be 
 difficult to give it the proper direction into the buckets, 
 especially if the openings are pretty wide for them; for then it 
 deviates the more do'wn from the line of direction, and tends 
 to retard the wheel, by striking on the outside of the bucket. 
 
 The openings from which the buckets are filled, ought to 
 oe 10 inches less in length than the buckets, f. c. five inches at 
 each side, otherwise the water is apt to jerk over on each 
 side of the wheel, as the edges of the bucket pass by. 
 
 The mode of making and finishing the wheel at Cartside 
 requires very little workmanship, compared to the usual 
 method 5 and any good joiner will do it as well as a mill- 
 wright. The joiner finished Cartside wheel in six or seven 
 weeks. The construction will be better understood from the 
 following reference to the figures. 
 
 Fig. 95 represents three distinct transverse views. The part 
 marked A supposes a part of the shrouding in section, showing 
 
86 
 
 THE OPERATIVE MECHANIC 
 
 the pins ; the part marked B is a section of the wheel through 
 any part of the buckets^ and showing three of the ties, 1 , 2 , 3 , 
 in section. Part D shows the manner in which the exterior 
 ends of the wheel are finished, also the gudgeons, flaunch, &c. 
 
 Fig. 96 is a longitudinal section of the wheel through one of 
 the arms, showing the projection of the shrouding, the manner 
 in which the arms of the wheel are connected together, and like- 
 wise the manner in which the ties are connected to the gudgeon. 
 
 CHAIN OF BUCKETS. 
 
 This is applicable in many situations where there is a 
 considerable fall of water. This sketch was taken from one 
 in Scotland used to give motion to a thrashing mill: the 
 fig. 97 is so obvious as to need little explanation. The 
 buckets t 5 D, G, H, &c. must be connected by several 
 chains to avoid the danger of breaking, and united into an 
 endless chain, which is extended over two wheels A and B, 
 the upper one being the axis which is to communicate motion 
 to the mill- work ; E is the spout to supply the water. The 
 principal advantage of this plan is, that no water is lost by 
 running out of the buckets before they arrive at the lowest 
 part, as is the case with the wdieel. Another is, that the 
 buckets being suspended over the wheel A of small diameter, 
 it may be made to revolve more quickly than a wheel of 
 large diameter, and without increasing the velocity of the 
 descending buckets beyond what is proper for them. This 
 saves wheel-work when the machine is to be employed, as in 
 a thrashing machine, to produce a rapid motion. On the 
 other hand, the friction of the chain in folding over the wheel 
 at the top, and seizing its cogs, will be very considerable; 
 these cogs must enter the spaces in the open links between 
 the buckets, to prevent the chain slipping upon the upper 
 wheel. We think this machine might be much improved by 
 contriving it so that the chain would pass through the centre 
 of gravity of each bucket, whereas in the present form, the 
 weight of each bucket tends to give the chain an extra bend. 
 
 The chain^pump reversed^ has been proposed as a substitute 
 for a water-wheel when the fall is very great, and we think 
 it would answer the purpose with some chance of success. 
 It would have an advantage over the chain-pump when em- 
 ployed for raising water, in the facility of applying cup 
 leathers to the pistons on the chain, in the same way as other 
 pumps, which leathers expand themselves to the inside of 
 the barrel, and are kept perfectly tight by the pressure of 
 the water. In the chain-pump such leathers cannot be 
 
& Stockl^ frojid 
 
 mk 
 
 
AND MACHINIST. 
 
 87 
 
 employed, because the edges of the leather cups would turn 
 down and stop the motion, when the cups were drawn 
 upwards into the barrel. It is the defective mode of leather- 
 ing the pistons of the chain-pump which occasions its great 
 friction. In the motion of a machine of this kind, the pistons 
 would descend into the barrel, and might therefore be lea- 
 thered with cups like other pumps, so as to be quite tight 
 without immoderate friction. This machine was proposed 
 by a Mr. Cooper in 1784, who obtained a patent for it, and 
 Dr. Robison has again proposed it with recommendation, 
 
 BREAST-WHEELS. 
 
 The breast-wheel partakes of the nature both of an over- 
 shot and an undershot: it is driven partly by impulse, but 
 chiefly by the weight of water. The lower part of the 
 wheel is surrounded by a curved wall or sweep of masonry, 
 which is made concentric with the wheel, and the float- 
 boards of the wheel are exactly adapted to the masonry, 
 so as to pass as near as possible thereto without touching it; 
 and the side walls are in like manner adapted to the end of 
 the float -boards or sides of the wheel, the intention being 
 to let the least possible quantity of water pass without causing 
 the float-boards to move before it. In fig. 98, the water is 
 poured upon the top of the wheel over the breasting at I, 
 the efflux from the mill-dam K being regulated by the sluice 
 or shuttle M, which is placed in the direction of a tangent to 
 the wheel, and is provided with the rack R, and pinion P, by 
 which it can be drawn up so as to make any required degree 
 of opening, and admit more or less water to flow on the wheel. 
 The water first strikes on the float, and urges it by its 
 impulse ; but when the floats descend into the sweep, they 
 form as it were close buckets, each of which will contain a 
 given quantity of water, and the water cannot escape from 
 these buckets except the wheel moves, at least this is the 
 intention, and the wheel is fitted as close as it can be to the 
 race with that view. Each of the portions of v/ater contained 
 in these spaces bears partly upon the wall of the sweep, and 
 partly upon the floats of the wheel ; and its pressure upon 
 the floats, if not exceeded by the resistance, will cause the 
 wheel to move; hence the action upon all the floats which 
 are within the sweep of the breasting is by the weight of the 
 water alone ; but the water is made to impinge upon the first 
 float-board with some velocity, because the surface of the 
 water in the dam K is raised considerably above the orifice 
 bei;eath the shuttle where the water issues. 
 
88 
 
 THE OPERATIVE MECHANIC 
 
 The Upper part of the fall at I is rounded off to a segment 
 of a circle, called the crown of the fall, and the water runs 
 over it. The lower edge of the shuttle when put down is 
 made to lit this curve, so as to make a tight joint; and in 
 consequence, when the shuttle is drawn up, the water will 
 run between its lower edge and the crown in a sheet or 
 stream which strikes upon the first float that presents itself, 
 nearly in a direction perpendicular to the plane of the float- 
 board, or of a tangent to the wheel. The float-boards of the 
 wheel are directed to the centre, but there are other boards 
 placed obliquely which extend from one float-board to the 
 rim of the wheel, and nearly fill the space between one float- 
 board and the next. These are called rising-boards, and the 
 use of them is to prevent the water flowing over the float- 
 board into the interior of the wheel; but the edges of these 
 boards are not continued so far as to join to the back of the 
 next float, because that would make all the boards of the 
 wheel close, and prevent the free escape of the air when the 
 water entered into the space between the floats. 
 
 As the water strikes with some force, the rising-boards are 
 very necessary to prevent the water from dashing over the 
 float-boards into the interior of the wheel. 
 
 This is the form of breast-wheel employed by Mr. Smeaton 
 in the great number of mills which he constructed ; but 
 although he speaks of the impulse of the water striking the 
 wheel, he always endeavoured to make the top of the breast- 
 ing, or crown of the fall, as high as possible ; so as to attain 
 the greatest fall and the least of the impulsive action. All 
 rivers and streams of water are subject to variation in height 
 from floods or dry seasons, and in some this is very consider- 
 able: it was therefore necessary to make the crown I of the 
 fall, at such a height as that, in the lowest state of the Avater 
 R, it Avould run over the crown in a sheet of three or four 
 inches in thickness, and work the wheel. When the water 
 rose higher in the mill-dam, it would then have a pressure to M 
 force it through, and in that case would strike the wheel solM 
 as to impel it by the velocity. 
 
 Mr. §meaton was well aware that the power communicated 
 by this impulse was very small. In some cases, where the « 
 water was very subject to variation, he used a false or mov- A 
 able crown, that is, a piece of wood which fitted to the crown * 
 I, and raised the surface thereof a foot or piore, so as to obtain 
 tlie greatest fall when the water stood at a mean height ; but I 
 when the water sunk too low to run over this movable I 
 crown, it‘ could be drawn up to admit the water beneath it, j 
 
AND MACHINIST. 
 
 89 
 
 This effect has since been produced in a more perfect manner 
 by making the crown of the fall a movable shuttle, to rise and 
 fall according to the height of the water in the mill-dam, by 
 which means the inconvenience before-mentioned is avoided. 
 
 IMPROVED BREAST-WHEEL, IN WHICH THE WATER RUNS OVER 
 THE SHUTTLE. 
 
 FiG.llOis a section of one of this kind. A is the water 
 which is made to flow upon the float-board B, and urges 
 the wheel by its weight only, the water being prevented 
 from escaping or flowing off the float-boards by the breast 
 or sweep D D, and the side-walls which enclose the floats 
 of the wheel. The upper part of the breast D D is made 
 by a cast-iron plate, curved to the proper sweep to line with 
 the stone-work. On the back of the cast-iron plate the 
 moving shuttle e is applied 3 it fits close to the cast-iron so as 
 to prevent the water from leaking between them, and the 
 water runs over its upper edge. F is an iron groove or 
 channel let into the masonry of the side-walls, and in these, 
 the ends of the sliding shuttle are received ; / is an iron rack, 
 which is applied at the back of the shuttle, and ascends above 
 the water-line where the pinion g is applied to it to raise or 
 lower the shuttle. The axis of the pinion is supported in a 
 frame of wood II, Z> H is a toothed sector and balance-weight, 
 which bears the shuttle upwards, or it might otherwise fall 
 down by its own weight, and put the mill in motion when 
 not intended. G is a strong planking, which is fixed across 
 between the two side- walls, and retains the water when it 
 rises very high, as in time of floods ; but in common times 
 the water rises only a few inches above the lower edge of the 
 planking. When the shuttle is drawn up to touch this lower 
 edge, the water cannot escape; but when the shuttle is 
 lowered down, it opens a space e through which the water 
 flows upon the float-boards of the wheel. 
 
 Fig. Ill is a section of the most improved form for a 
 breast- wheel, taken from the Royal Armoury Mills at Enfield 
 Lock, erected by Messrs. Lloyd and Ostel. The general 
 description of this, is like the former, but it is constructed in 
 a better manner, and unites strength with durability. The 
 breast of masonry is surmounted by a cast-iron plate A, 
 
 feet high, which is let into the masonry of the side- walls 
 at each end, and the lower part is formed with a flanch, by 
 which it is bolted to the stone breast at top, v This plate is 
 made straight at the back for the shuttle B to lie against, 
 ^pd it slides up and down. The ends of the gate are guided 
 
90 
 
 THE OPERATIVE MECHANIC 
 
 by iron groove pieces or channels which are let into the 
 stone-work of the side walls, and being made wedge-like, 
 they fix the ends of the cast-iron breast fast in its place. 
 Tlie grooves are not upright, but inclined to the perpendicular 
 so much, that the plane of the gate is at right angles to a 
 radius of the wheel drawn through the point where the water 
 falls upon the wheel. D is a strong plank of wood, extended 
 between the iron grooves just over the shuttle. When the 
 shuttle is drawn up it comes in contact with the lower side 
 of this piece of wood, and stops the water; but the piece D is 
 fixed at such a height, that the water will run clear beneath 
 it, unless its surface rises above its mean height. 
 
 The float-boards of the wheel do not point to the centre of 
 the wheel, but are so much inclined thereto that they are 
 exactly horizontal at the point where the water first flows 
 upon them. In this way, the gravity of the water has its full 
 effect upon the wheel, and the boards rise up out of the tail- 
 water in a much better position, than if they pointed to the 
 centre of the wheel; this is more particularly observable 
 when the wheel is flooded by tail-water penned up in the 
 lower part of the race, so that it cannot run freely away from 
 the wheel. The dimensions of this wheel are as follows; 
 diameter 18 feet to the points of the floats, and 14 feet 
 wide; the float-boards are 40 in number, each 16 inches 
 wide, and each rising-board 11 inches wide. The wheel is 
 formed of four cast-iron circles or wheels, each 14 feet 
 8 inches diameter, placed at equal distances upon the central 
 axis, which is 14 feet 8 inches long between the necks or 
 bearings, and 9 inches square; the bearing-necks are 9J 
 inches diameter. The wheel is calculated to make four revo- 
 lutioiis per minute, which gives near feet per second for 
 the velocity with which the float-boards move. The fall of 
 water is six feet, and the power of the wheel, when the 
 shuttle is drawn down one foot perpendicular, equal to 
 28-horse power. 
 
 BREAST-WHEEL WITH TWO SHUTTLES. 
 
 In this wheel the piece of wood marked D in the last 
 figure, is fitted into the groove of the shuttle, and is provided 
 with racks and pinions to slide up and down, independently of 
 the lower shuttle. This enables the lower shuttle to rise aifd 
 fall, according to the height of the water, so that the water shall 
 always run over the top of it, in the proper quantity to work 
 the mill with its required velocity, whilst the upper shuttle is 
 only used to stop the mill by shutting it down upon the 
 
AND MACHINIST. 
 
 91 
 
 lower shuttle, and preventing the water from running over it. 
 This plan is used when the mill is to be regulated by a 
 governor, or machine to govern its velocity ; in that case the 
 governor is made to operate upon the lower shuttle, and wdll 
 raise it up, or lower it down, according as the mill takes too 
 much or too little water, and this regulates the supply ; but 
 the upper shuttle is used to stop the mill, and by this means 
 the adjustment of the lower shuttle is not destroyed, but 
 when set to work again, it will move with its required 
 velocity. Fig. 101 is a section of one of the water-wheels 
 at the cotton-mills of Messrs. Strutt, at Helper, in Derby- 
 shire. The width of this wheel is very great, and to render 
 the shuttles A B firm, a strong grating of cast-iron is 
 fixed on the top of the breast K, and the shuttles are 
 applied at the back of the grating E, so as to slide up and 
 down against it, the strain occasioned by the pressure of the 
 water being borne by the grating. The lower shuttle is 
 moved by means of long screws, a, which have bevelled 
 wheels, b, at the upper ends, to turn them, by a connection 
 of wheel-work with the wheel- work of the mill. The upper 
 shuttle. A, is drawn up or down by racks and pinions, c, 
 which are turned by a winch, or handle. The bars of the 
 grating E are placed one above the other, like shelves, but 
 are not horizontal; they are inclined, so that the upper sur- 
 faces of all the bars form tangents to an imaginary circle of 
 one-third the diameter of the wheel described round the 
 centre thereof. These bars are not above half an inch thick, 
 and the spaces between them are 2^ inches. The bars are of 
 a considerable breadth, the object of them being to lead the 
 water, with a proper slope from the top of the lower shuttle 
 B, to flow upon the floats of the wheel. This disposition 
 allow^s the shuttles to be placed at such a distance from the 
 wheel as to admit very strong upright bars of cast-iron to 
 be placed between the wheel and the shuttles, for the shuttles 
 to bear against, and prevent them from bending towards the 
 wheel, as the great weight of water would otherwise occasion 
 them to do. These upright bars are very firmly fixed to 
 the stone-work of the breast at their lower ends, and the 
 upper ends are fastened to a large timber, D, which is sup- 
 ported at its ends in the side walls, and has a truss-framing 
 a*pplied to the back of it, like the framing of a roof, to prevent 
 it from bending towards the wheel. The upright bars are 
 placed at distances of five feet asunder, so as to support the 
 shuttles in two places in the middle of their length, as u eli 
 as at both ends ; and large rollers are applied m the shuttle. 
 
92 
 
 THE OPERATIVE MECHANIC 
 
 where it bears against these bars, to diminish the friction, 
 which would otherwise be very great. 
 
 These precautions will not appear unnecessary when the 
 size of the work is known. The wheel is 21i feet in dia- 
 meter, and 15 feet broad; the fall of water is 14 feet, when 
 it is at a mean height; the upper shuttle is feet high, and 
 15 feet long; the lower shuttle is five feet high, and the same 
 length, so that it contains 7^ square feet of surface exposed 
 to the pressure of the water; now taking the centre of 
 pressure at two-thirds of the depth, or 3^ feet, we find 
 the pressure equal to that depth of water acting on the whole 
 surface; that is, the weight of 3->- cubic feet of water = 208 
 pounds, bears on every square foot of surface, which is equal 
 to 15,^0 pounds, or near seven tons, on the lower shuttle 
 only ; but if we take the two shuttles together, the surface is 
 112 square feet, and the mean pressure 312 pounds upon 
 each, or 16 tons in the whole. The wheel has 40 float- 
 boards pointing to the centre. The wheel is made of cast-iron. 
 There are two wheels of the dimensions above stated, which 
 are placed in a line with each other, and are only separated 
 by a wall which supports the bearings ; for they work toge- 
 ther as one wheel, and the separation is only to obviate the 
 difficulty of making one wheel of such great breadth as 30 feet, 
 though this is not impossible, for there is a wheel in the same 
 works 40 feet in breadth, but it is of wood and not iron, and 
 is framed in a particular manner, — ^Dr. Rees’s Cyclopcedia, 
 
 DR. barker’s mill. 
 
 Dr. Desaguliers appears to have been the first who pub- 
 lished an account of this machine. He ascribes the invention 
 to Dr. Barker, in the following words : Sir George Savill says, 
 
 he had a mill in Lincolnshire to grind corn, which took up so 
 much water to work it, that it sunk his ponds visibly, for 
 which reason he could not have constant work ; but now, by 
 Dr. Barker’s improvement, the waste water only from Sir 
 George’s ponds keeps it constantly to work.” 
 
 Dr. Barker’s mill is shown in fig. 102, where CD is a 
 vertical axis, moving on a pivot at D, and carrying the upper 
 millstone m, after passing through an opening in the fixed 
 millstone C. Upon this axis is fixed a vertical tube T T, 
 communicating with a horizontal tube A B, at the extremities 
 of which. A, B, are two apertures in opposite directions. 
 When water from the millcourse M N is introduced into the 
 tube TT, it flows out of the apertures A, B, and, by the 
 reaction or counterpressure of the issuing water, the arm AB, 
 
AND MACHINIST. 
 
 93 
 
 and consequently the whole machine, is put in motion. 
 The bridgetree a b is elevated or depressed by turning the 
 nut c at the end of the lever c b. In order to understand 
 how this motion is produced, let us suppose both the aper- 
 tures shut, and the tube T T filled with water up to T. The 
 apertures A, B, which are shut up, will be pressed outwards 
 by a force equal to the weight of a column of water whose 
 height is TT, and whose area is the area of the apertures. 
 Every part of the tube AB sustains a similar pressure; but 
 as these pressures are balanced by equal and opposite 
 pressures, the arm A B is at rest. By opening the aperture 
 at A, however, the pressure at that place is removed, and 
 consequently the arm is carried round by a pressure equal to 
 that of a column T T, acting upon an area equal to that of 
 the aperture A. The same thing happens on the arm T B ; 
 and these two pressures drive the arm A B round in the 
 same direction. This machine may evidently be applied to 
 drive any kind of machinery, by fixing a wheel upon the 
 vertical axis C D. 
 
 In the preceding form of Barker’s mill, the length of the 
 axis C D must always exceed the height of the fall N D, 
 and therefore when the fall is very high, the difficulty of 
 erecting such a machine would be great. In order to remove 
 this difficulty, M. Mathon de la Cour proposes to introduce 
 the water from the millcourse into the horizontal arms A, B, 
 which are fixed to an upright spindle C T, but without any 
 tube T T. The water will obviously issue from the apertures 
 A, B, in the same manner as if it had been introduce-d at the 
 top of a tube TT as high as the fall. Hence the spindle 
 C D may be made as short as we please. The practical 
 difficulty which attends this form of the machine, is to give 
 the arms A, B, a motion round the mouth of the feeding pipe, 
 which enters the arm at D, without any great friction, or 
 any considerable loss of water. This form of the mill is 
 shown in fig. 103, where F is the reservoir, K the millstones, 
 K D the vertical axis, F E C the feeding pipe, the mouth of 
 which enters the horizontal arm at C. In a machine of this 
 kind which M. Mathon de la Cour saw at Bourg Argental, 
 A B was 92 inches, and its diameter three inches ; the dia- 
 meter of each orifice was 14- inch, F G was 21 feet ; the 
 internal diameter of D was two inches, and it was fitted into 
 C by grinding. This machine made 115 turns in a minute 
 when it was unloaded, and emitted water by one hole only. 
 The machine, when empty, weighed 80 pounds, and it was 
 half supported by the upward pressure of the water. 
 
94 
 
 THE OPERATIVE MECHANIC 
 
 This improvement^ which was first given by M. Mathon ile 
 la Cour, in the Journal de Physique^ 177^^ appeared twenty 
 years afterwards in the American Philosophical Transactions^ 
 as the invention of a Mr. Ramsey; and Mr. Waring, who in- 
 serted the account, contrary to every other philosopher, makes 
 the effect of the machine only equal to that of a good under- 
 shot wheel, moved with the same quantity of water falling 
 through the same height. 
 
 Dr. Gregory, in his Mechanics, vol. ii. has given this 
 paper with some corrections, and recommends it as the best 
 theory. The following rules, deduced from his calculus, 
 may be of use to those who wish to make experiments on 
 the effect of this interesting machine. 
 
 1 . Make each arm of the horizontal rotatory tube or arm 
 of any convenient length, from the centre of motion to the 
 centre of the apertures, but not less than one-third (one- 
 ninth, according to Mr. Gregory) of the perpendicular height 
 of the water’s surface above their centres. 
 
 2. Multiply the length of the arm in feet by .6136, and 
 take the square root of the product for the proper time of a 
 revolution in seconds, and adapt the other parts of the ma- 
 chinery to this velocity; or if the required time of a revolution 
 be given, multiply the square of this time by 1.629 for the 
 proportional length of the arm in feet. 
 
 3. Multiply together the breadth, depth, and velocity per 
 second, of the race, and divide the last product by 18.47 
 times (14.27, according to Mr. Gregory) the square root of 
 the height, for the area of either aperture. 
 
 4. Multiply the area of either aperture by the height of 
 the fall of water, and the product by 414 pounds (55. 77^, 
 according to Mr. Gregory) for the moving force, estimated 
 at the centres of the apertures in pounds avoirdupois. 
 
 5. The power and velocity at the aperture may be easily 
 reduced to any part of the machinery by the simplest me- 
 chanical rules. 
 
 TIDE-MILLS. 
 
 Tide-mills, as their name imports, are such as employ 
 for their first mover the flowing and ebbing tide, either in 
 the sea or a river. 
 
 Mills of this kind have not often, we believe, been erected 
 in England, though several of our rivers, and particularly 
 the Thames, the Humber, and the Severn, in which the tide 
 rises co a great height, furnish a very powerful mover to 
 drive any kind of machinery, and would allow of tide-mills 
 

 JFLio. 
 
 
 103 
 
 105 
 
 t'roni 102 t/)J03 
 
 102 
 
 H 
 
--S. 
 
AND MACHINIST. 
 
 95 
 
 being very advantageously constructed upon their banks. 
 The erection of such mills is not to be recommended uni- 
 versally, as they are attended with a considerable original 
 expense ; beside that, some of their parts will require frequent 
 repairs : but in some places, where coal is very dear, they 
 may, on the whole, be found less expensive than steam- 
 engines to perform the same work, and may, on that account, 
 be preferred even to them. 
 
 We have not been able to ascertain who was the first 
 contriver of a tide-mill in this country, nor at what time one 
 was first erected. The French have not been so negligent 
 respecting the origin of this important invention, as to let 
 it drop into obscurity ; but have taken care to inform us 
 that such mills were used in France early in the last century. 
 Belidor mentions the name of the inventor, at the same 
 time that he states some peculiar advantages of this species 
 of machine. L’on en attribue,” says he, la premiere 
 invention a un nomm^ Perse, maitre charpentier de Dun- 
 kerque, que merite assurement beaucoup d’eloge, n’y ayant 
 point de gloire plus digne d’un bon citoyen, que cede de 
 produire quelqu’invention utile a la societe. En effet, 
 combien n’y a-t’-il point de choses essentielles a la vie, dont 
 on ne connolt le prix que quand on en est prive : les 
 moulins en general sont dans ce cas-la. On doit s 9 avoir bon 
 gre a ceux qui nous ont mis en etat d’en construire partout : 
 par exemple, a Calais, comme il n’y serpente point de 
 rivieres, on n’y a point fait jusqu’ici de moulins a eau, et ceux 
 qui vont par le vent chomant une partie de I’annee, il y a des 
 terns ou cette ville se trouve sans farine, et j’ai vu la 
 gamison en 1730, oblige de faire venir du pain de Saint-Omer, 
 au lieu qu’en se servant du flux et reflux de la mer, on pour- 
 rait construire autant de moulins a eau que Ton voudroit ; il 
 y a d’autres villes dans le voisinage de la mer sujettes au 
 m^me inconvenient, parcecju’apparemment elles ignorent le 
 moyen d’y rem^dier.” 
 
 Mills to be worked by the rising and falling of the tide, 
 admit of great variety in the essential parts of their con- 
 struction ; but this' variety may perhaps be reduced to four 
 general heads, according to the manner of action of tlie 
 water-wheel. 1. The water-wheel may turn one way when 
 the tide rises, and the contrary when it falls. 2. The water- 
 wheel may be made to turn always in one direction. 
 3. The water-wheel may fall and rise as the tide ebbs and 
 flows. 4. The axle of the water-wheel may be so fixed as 
 that it shall neither rise nor fall, though the rotatory motion 
 
THE OPERATIVE MECHANIC 
 
 96 
 
 shall be given to the wheel, while at one time it is only;^ ! 
 partly, at another completely, immersed in the fluid. In the ^ i 
 mills we have examined, says Dr. Gregory, the first and third of < j 
 these idivisions have been usually exemplified in one machine ; ~ 
 
 and the second and fourth may readily be united in another : 
 we shall, therefore, speak of them under two divisions on y. 
 
 1. When the water-wheel rises and falls, and turns one^B 
 way with the rising tide, and the contrary when it ebbs. In^H 
 order to explain the nature of this species of tide-mills, we^K 
 shall describe one which has lately been erected on the^B 
 right bank of the Thames, at East- Greenwich, under the^ 
 direction of Mr. John Lloyd, an ingenious engineer of*' 
 Brewer *s-green, Westminster. 
 
 This mill is intended to grind com, and works eight pair S 
 of stones. The side of the mill-house parallel to the course^B 
 of the river, measures 40 feet within ; and as the whole of thi&^B 
 may be opened to the river by sluice-gates, which are carried 
 down to the low water- mark in the river, there is a 40 feet ^ 
 waterway to the mill : through the waterway the water X 
 presses during the rising tide into a large reservoir, which S 
 occupies about four acres of land ; and beyond this reservoir ^ 
 is a smaller one, in which water is kept, for the purpose of 
 being let out occasionally at low water to cleanse the whole t 
 works from mud and sediment, which would otherwise, in J| 
 time, clog the machinery. ® 
 
 The water-wheel has its axle in a position parallel to the 
 side of the river, that is, parallel to the sluice-gates which Jj; 
 admit water from the river ; the length of this wheel is 26 | 
 feet, its diameter 11 feet, and its number of float-boards 32. i: 
 These boards do not each run on in one plane from one end ® 
 of the wheel to the other, but the whole length of the wheel is jH 
 divided into four equal portions, and the parts of the float-boards, ^B 
 belonging to each of these portions, fall gradually one lower than 
 another, each by one-fourth of the distance from one board ^B 
 to another, measuring on the circumference of the wheel. 
 
 This contrivance, which will be better understood by refer- a 
 ring to fig, 104, is intended to equalize the action of water A 
 upon the wheel, and prevent its moving by jerks. The wheel, B 
 with its incumbent apparatus, weighs about 20 tons, the whole 
 of which is raised by the impulse of the flowing tide, when ^B 
 admitted through the sluice-gates. It is placed in the middle .^B 
 of the waterway, leaving a passage on each side of about six 9 
 feet, for the water to flow into the reservoir, besides that which, 9 
 in its motion, turns the wheel round. Soon after the tide has ,9 
 risen to the highest, (which at this mill is often 20 feet above, | 
 
AND MACHINIST. 
 
 97 
 
 the low water-mark,) the water is permitted to run back 
 again from the reservoir into the river, and by this means it 
 gives a rotatory motion to the water-wheel, in a contrary 
 direction to that with which it moved when impelled by the 
 rising tide : the contrivance by which the wheel is raised and 
 depressed, and that by which the whole interior motions of 
 the mill are preserved in the same direction, although that in 
 which the water-wheel moves is changed, are so truly inge- 
 nious as to deserve a distinct description, illustrated by 
 diagrams. Let, then, AB (fig 105) be a section of the 
 water-wheel, 1, 2, 3, 4, 5, &c. its floats ; C D the first cog- 
 wheel upon the same axis as the water-wheel ; the vertical 
 shaft F E carries the two equal wallower-wheels E and F, 
 which are so situated on the shaft that one or other of them 
 may, as occasion requires, be brought to be driven by the 
 first wheel C ID ; and thus the first wheel acting upon F and 
 E at points diametrically opposite, will, although its own 
 motion is reversed, communicate the rotatory motion to the 
 vertical shaft always in the same direction. In the figure 
 the wheel E is shown in geer, while F is clear of the cog- 
 wheel CD; and at the turn of the tide the wheel F is let 
 into geer, and E is thrown out ; this is effected by the lever 
 G, whose fulcrum is at H, the other end being suspended by 
 the rack K, which has hold of the pinion L on the same axle 
 as the wheel M ; into this wheel plays the pinion N, the 
 winch O, on the other end of whose axle, furnishes sufificient 
 advantage to enable a man to elevate or depress the wallower- 
 w^heels, as reqilfred. 
 
 The centre of the lever may be shown more clearly by 
 fig. 104, where «Z> is a section of the lever, which is com- 
 posed of two strong bars of iron, as « Z> ; there are two steel 
 studs or pins which w^ork in the grooves of the grooved wheel 
 I, this w^heel being fixed on the four rods surrounding the 
 shaft, of which three only can be shown in the figures, as 
 cde; the ends of these are screwed fast by bolts to the 
 sockets of the wallower-wheels, and they are nicely fitted 
 on the vertical shaft, so as to slide with little friction ; thus 
 the wallowers may be raised or lowered upon the upright 
 shaft, while the gudgeon, on which it turns, retains the same 
 position. 
 
 When the top wallower is in geer, it rests on a shoulder 
 that prevents it from going too far down ; and wLen the 
 bottom one is in geer, there is a bolt that goes through the 
 top wheel socket and shaft which takes the weight from the 
 lever G, at the same time that it prevents much friction on 
 
 H 
 
THE OPERATIVE MECHANIC 
 
 the stuas or pins of the lever v*^hich works in the grooved 
 wheel I. 
 
 When the tide is flowing, after the mill has stopped a suf- 
 ficient time to gain a moderate head of water, the fluid is 
 suffered to enter and fall upon the wheel at the sluice Q, 
 (fig. 105,) and the tail water to run out at the sluice R. 
 
 The hydrostatic pressure of the head of water acting against 
 the bottom of the wheel -frame S, and at the same time act- 
 ing between the folding-gates T W, which are thus converted 
 into very large hydrostatic bellows, buoys up the wheel and 
 frame, (though weighing, as before observed, nearly 20 tons,) 
 and makes them gradually to rise higher and higher, so that 
 the wheel is never, as the workmen express it, drowned in the 
 flowing water ; nor can the water escape under the wheel- 
 frame, being prevented by the folding-gates, which pass from 
 one end to the other of the wheel. In this way the wheel 
 and frame are buoyed up by a head of four feet ; and the mill 
 works with a head of 5 or 5.^ feet. 1 
 
 When the tide is ebbing, and the water from the reservoir 
 running back again into the river, it might, perhaps, be ex- 
 pected that in consequence of the gradual subsiding of the 
 water, the water-wheel should as gradually lower ; but lest 
 any of the water confined between the wheel-frame at S, and 
 the folding-gates T W, should prevent this, there are strong 
 rackworks of cast-iron, by which the wheel-frame can be 
 either suspended at any altitude, or gradually let down so as 
 to give the water returning from the reservoir an advantageous 
 head upon the wheel ; then the sluice R is shut, and V opened 
 as well as X, the water entering at X to act upon the wheel, 
 and flowing out at R. The upper surface of the wheel-frame 
 is quadrangular, and at each angle is a strong cast-iron bar, 
 which slides up and down in a proper groove, that admits of 
 the vertical motion, but prevents all sucli lateral deviation 
 as might be occasioned by the impulsion of the stream. 
 
 At each end of the water-wheel there is a vertical shaft, 
 with wallowers and a first cog-wheel, as F E, and C D ; and 
 each of these vertical shafts turns a large horizontal wheel at 
 a suitable distance above the wallowers, while each horizontal 
 wheel drives four equal pinions placed at equal or quadrantal 
 distances on its periphery, each pinion having a vertical 
 spindle, on the upper part of which the upper millstone of 
 its respective pair is fixed. Other wheels, driven by one or 
 other of these pinions, giving motion to the bolting and 
 dressing machines, and different suboi*dinate parts of the 
 mill. 
 
AND MACHINIST. 
 
 99 
 
 Although the vertical shaft at each end of the water-wheel 
 rises and falls with that wheel, yet the large horizontal wheel 
 turning with such shaft does not likewise rise and fall, but 
 remains always in the same horizontal plane, and in contact 
 with the four pinions it drives. The contrivance for this 
 purpose is very simple, but very efficacious ; each great 
 horizontal wheel has a nave, which runs upon friction-rollers, 
 and has a square aperture passing through it vertically, just 
 large enough to allow the shaft P to slide freely up and down in 
 it, but not to turn round without communicating its rotatory 
 motion to the wheel ; thus the weight of the wheel causes it 
 to press upon the friction-rollers, and retain the same hori- 
 zontal planes, and the action of the angles of the vertical shaft 
 upon the corresponding parts of the square orifice in the 
 nave causes it to partake of the rotatory motion, such motion 
 being always in one direction, in consequence of the con- 
 trivance by which one or other of the wallowers E F is 
 brought into contact with the opposite points of the first cog- 
 wheel C D. 
 
 Several of the subordinate parts of this mill are admir- 
 ably constructed 5 but we can only notice here the means by 
 which the direction of the motion in the dressing and bolt- 
 ing machines may be varied at pleasure. On a vertical 
 shaft are fixed^ at the distance of about 15 or 18 inches, two 
 equal cog-wheels, and another toothed-wheel, attached to a 
 horizontal axle, is made so as to be movable up and down by 
 a screw, and thus brought into contact with either the 
 upper or lower of the two cog-wheels on the vertical shaft ; 
 thus, it is manifest, the motion is reversed with great faci- 
 lity by changing the position of the horizontal axle so that 
 the wheel upon it may be driven by the two cog-wheels 
 alternately. A wheel and pinion working at the other end 
 of the horizontal axle will communicate the motion to the 
 dressing machines. 
 
 Mr. W. Dryden, Mr. Lloyd’s foreman, employed in the 
 erection of this mill, suggests that a nearly similar mode 
 may be advantageously adopted in working dressing ma- 
 chines in wind-mills ; three wheels, all of different diameters, 
 may be employed, two of them, as A and C, turning upon a 
 vertical shaft, and the third, B, upon an inclined one. In 
 fig. 106, the wheels A and B are shown in geer, while C is 
 out ; and if A be struck out by some such contrivance as is 
 adopted with regard to the first cog-wheel and wallowers, 
 (fig. 104 and 105,) C would come in contact with B, while, A 
 would be free, and so communicate a motion to B the reverse 
 
 H 2 
 
100 
 
 THE OPJERATIVTS MECHANIC 
 
 way. By this contrivance it would be easy^ when the winds 
 are strong and give a rapid motion to the vertical axle, to 
 bring C to drive B, the wheel on the axle of the dressing- 
 machines ; and on the contrary, when the wind is slack, 
 and the consequent motion of the machinery slow, let C be 
 thrown out of geer, and the wheel B driven by the larger 
 wheel A, as shown in the figure. 
 
 We should have been glad to see adopted in this well- 
 constructed mill, a contrivance, recommended and pursued 
 by the American mill-wrights, for raising the ground corn to 
 the cooling-boxes or beaches from which it is to be con- 
 veyed into the bolting-machine. In this mill, as in all we 
 have seen, the corn is put into bags at the troughs below the 
 mill-stones, and thence raised to the top of the mill-house by 
 a rope folding upon barrels turned by some of the interior 
 machinery of the mill. In the American method, a large 
 screw is placed horizontally in the trough which receives 
 the flour from the mill- stones. The thread or spiral line of 
 the screw is composed of pieces of wood about two inches 
 broad and three long, fixed into a wooden cylinder seven or 
 eight feet in length, which forms the axis of the screw. 
 When the screw is turned round this axis, it forces the meal 
 from one end of the trough to the other, where it falls into 
 another trough, from which it is raised to the top of the mill- 
 house by means of elevators, a piece of machinery similar to 
 the chain-pump. These elevators consist of a chain of buckets, 
 or concave vessels, like large tea-cups, fixed at proper 
 distances upon a leathern band, which goes round two wheels, 
 one of which is placed at the top of the mill-house, and the 
 other at the bottom, in the meal-trough. When the wheels 
 ,are put in motion, the band revolves, and the buckets, dip- 
 ping into the meal-trough, convey the flour to the upper story, 
 where they discharge their contents. The band of buckets 
 is enclosed in two square boxes, in order to keep them clean, ? 
 and preserve them from injury. 
 
 We shall now proceed, tMj 
 
 2. To tide-mills, in which the axle of the water-wheelW 
 neither rises nor falls, and in which that wheel is made always™ 
 to revolve in the same direction. A water-wheel of this kind 
 must, manifestly, at the time of high-tide, be almost, if not 
 entirely, immersed in the fluid ; and to construct a wheel to 
 work under such circumstances is, obviously, a matter which 
 requires no small skill and ingenuity. 
 
 The first person who devised a wheel which might be 
 turned by the tide, when completely immersed in it, were 
 
AND MACHINIST. 
 
 101 
 
 I Messrs. Gosset and De la Deuille. Their wheel is described 
 by Belidor in nearly the following terms. Suppose G H 
 (fig. 107 ) to denote the surface of the water at high-tide^ the 
 hne L M the surface at low- water, and that the current fol- 
 lows the direction of the arrow N ; the problem is to construct 
 I the wheel so that it may always turn upon its axis I K. 
 
 The figure just referred to is a profile of an assemblage of 
 I carpentry, which must be repeated several times along the 
 arbor, according to the length which it is proposed to give to 
 the float-boards ; and the planks or plates which compose 
 these floats, must be hung to the other parts of the frame by 
 as many joints as are necessary, to enable them to sustain 
 the impulse of the water without bending. The sole pecu- 
 liarity of this wheel consists in hanging upon the transverse 
 beams in the frame-work, by hinges, the planks which are to 
 compose the float-boards ; so that they may present them- 
 selves in face, as D, D, D, when they are at the bottom of the 
 wheel, to receive the full stroke of the stream ; and, on the 
 contrary^, they present only their edges, as A, A, A, when 
 they are brought towards the summit of the wdieel ; hence, 
 the water having a far greater effect upon the lower than the 
 upper parts of the wheel, compels it to revolve in the order 
 of the letters ; instead of which, if the float-boards were 
 fixed as in the usual way, the impulse of the fluid upon the 
 wheel would be nearly the same in all its parts, and it would 
 remain immovable. 
 
 We see, at once, that the boards D, D, D, having moved 
 towards M, then begin to float, as at E, E, E, and more still 
 I at F, F, F, but that it is not till they arrive at A, A, A, that 
 they attain the horizontal position ; after that, having arrived 
 at B, B, B, they begin to drop towards the beams to which 
 they are hooked, and as soon as they have passed the level of 
 the axle I K, the stream commences its full action upon 
 them, which it attains completely between C, C, C, and 
 E, E, E, and this, whether the surface of the w^ater be at 
 G H or at L M ; for even in the latter case it is manifest that 
 the float-boards are entirely immersed when in the vertical 
 position P Q. Belidor says, he was present at the first 
 trial of such a wheel at Paris, and that it was attended with 
 all the success that could be desired. 
 
 A water-wheel has been lately invented by Mr. Dryden, 
 which will work when nearly immersed in the water of a 
 flowing tide. Fig. 108 is an elevation of this wheel, its upper 
 parts being supposed to stand a foot or two higher than the 
 tide ever rises ; the axis of this wheel remains always in one 
 
102 
 
 THE OPERATIVE MECHANIC 
 
 place, and the wheel will work at high-water when the head 
 is at B, and the tail- water at the dotted line A ; it will also 
 perform nearly the same work when the head is at C, and the 
 tail- water level with the bottom of the wheel. The floats 
 are all set at one and the same angle, with the respective 
 radii of the wheel, as may be seen in the figure, and are made 
 so as to have an opening of at least an inch between each 
 float and the drum-boarding of the wheel. This opening is 
 intended to prevent the wheel from being impeded by the 
 tail- water; for as the bucket rises out of the water, there 
 can be no vacuum formed in it, there being a full supply of 
 air, in consequence of which the water leaves the wheel de- 
 liberately. The case is different with regard to wheels made 
 in the common way ; for if such are open wheels, the floats 
 are made in such a manner as to throw the tail-watei if they 
 are immersed any depth in it ; or, if they are close, the w'heel 
 wants proper vent for the air to prevent the formation of a 
 vacuum in the rising bucket, or what is called by the miller 
 
 sucking up the tail-water.” At D is planking made cir- 
 cular to fit the wheel pretty close for rather more than the 
 space of two floats, so as to confine the water nearly close to 
 the wheel. E, F, G, H, are sluices which are all connected 
 together by the iron bar I, • and lifted with the assistance of 
 the wheel, two pinions, and a winch, the first pinion working 
 into the rack K ; these sluices are merely for stopping the 
 wheel when occasion requires, although one might be suffi- 
 cient to supply the wheel. The rings of this wheel may be 
 made either of cast-iron or of wood ; the floats may be iron 
 plates rivetted together. The flanches on the arms of the 
 wheel, exhibited in the sketch, are intended to facilitate the 
 fixing of the first cog-wheels ; the ring of the wheel may be 
 fixed to the flanches at the extremity of the arms, and the 
 large flanch made fast to the axle will receive the middle part 
 of the wheel. 
 
 Fig. 109 is a plan of the house in which either of the two 
 latter wheels may be fixed, showing in what manner the 
 water may be conveyed always on one side of the wheel by 
 the assistance of the four gates A, B, C, and D. When the 
 mill is working from the river, A and B are open, the arrows 
 point out the way the water runs from the river to the basin ; 
 and the dotted lines on the contrary the course from the basin 
 to the river, when A, B, are shut, and C, D, opened. These 
 gates are made to turn on an axle, which is about six inches 
 from the middle of the gate, and on the top of the axle is a 
 half- wheel ; by some crane- work connected to it, the gate 
 
AND MACHINIST. 
 
 103 
 
 can be opened or bhiit at pleasure ; when a head of water 
 presses against the gates they will open great part of the 
 way of themselves, by only letting the catches that keep them 
 shut be lifted out of their place. X, Y, are two knees of 
 cast-iron, to support the posts that the gates are fixed to. 
 The walls of the building are represented at a, Z», c, and d. 
 
 The reader will now be able to form an estimate of the 
 comparative value and ingenuity of the two kinds of tide- 
 mills here described. The simplicity of construction of the 
 wheels of Gosset, De la Deuille, and Dryden, recommend 
 them strongly ; but we entertain some doubts of their being 
 completely successful in practice : had the curious wheel, 
 with the folding-gates, &c. fig. 104 and 106, been placed 
 with its axle perpendicular, instead of parallel, to the course 
 of the river, the water might then have always been admitted 
 to act upon the same side of it, and the hydrostatic pressure 
 would have operated as completely in lowering it continually 
 during the time of ebb, as in raising it continually during the 
 rising of the tide ; thus, as appears to us, would the labour 
 of a man be saved, who, according to the present construc- 
 tion, must attend the water-wheel; and all the additional 
 apparatus now requisite to shift the spur-wheels, would at 
 the same time be saved, and a consequent diminution of 
 original expense. Dr. Gregory's Mechanics, vol. ii. 
 
 In selecting a site for the erection of a mill, the engineer 
 must be careful not to make choice of a spot that is liable to 
 be flooded. When the water in the mill-tail will not run off 
 freely, but stands pent up in the wheel-race, so that the 
 wheel must work or row in it, the wheel is said to be tailed, 
 or to be in back-w^ater or tail-water ; wdiich greatly impedes 
 the velocity of the wheel, and, if the flood be great, com- 
 pletely stops it. 
 
 Every mill that is well and properly constructed, will clear 
 itself of a considerable depth of tail- water, provided there is, 
 at the time, an increase in the height of the water in the 
 mill-dam or head, and an unlimited quantity of water to draw 
 upon the wheel. Common breast-mills will bear two feet of 
 tail-water, when there is an increase of head, and plenty of 
 water to be drawn upon the wheel, without prejudice to their 
 performance ; and mills that are well constructed, with slow 
 moving wheels, will bear three and even four feet aud up- 
 wards of tail-water. Mr. Smeaton mentions having ?ten an 
 instance of six feet ; and it is a common thing in leve coun- 
 tries, where tail-water is most annoying, to lay the wheel 
 from six to twelve inches below the water's level ?f the 
 
104 
 
 THE OPERATIVE MECHANIC 
 
 pond below, in order to increase the fall of water 5 and, if 
 judiciously applied, is attended with good effect, as it in- 
 creases the diameter of the wheel, and though it must 
 always work in that depth of tail- water, it will perform full 
 as well, because the water ought to run off from the bottom 
 of the wheel, in the same direction as the wheel turns. 
 
 ON THE CONSTRUCTION OF THE WHEEL-RACE 
 WATER-COURSE. 
 
 AND 
 
 The wheel-race should always be built in a substantial 
 manner with masonry, and if the stones are set in Roman 
 cement, it will be much better than common mortar. The 
 earth, behind the masonry, should be very solid, and if it is 
 not naturally so, it should be hard rammed and puddled, to 
 prevent percolation of the water. This applies more parti- 
 cularly to breast-wheels, in which the water of the dam or 
 reservoir is usually immediately behind the wall or breast in 
 which the wheel works, a sloping apron of earth being laid 
 from the wall in the dam to prevent the water leaking. The 
 wall of the breast should have pile planking driven beneath, 
 to prevent the water from getting beneath, because that might 
 blow up the foundation of the race. The stones of the race 
 are hewn to a mould, and laid in their places with great care ; 
 but afterwards, when the side walls are finished, and the axis 
 of the wheel placed in its bearings, a gauge is attached to it 
 and swept round the curve, and by this the breast is dressed 
 smooth, and hewn to an exact arch of a circle ; the side w^alls, 
 in like manner, are hewn flat and true at the place where the 
 float-boards are to work. It is usual to make the space be-- 
 tween the side walls two inches narrower at each side, in the 
 circular part where the float acts, than in the other parts. 
 
 In some old mills the breast is made of wood planking, 
 but this method has so little durability that it cannot be 
 recommended. 
 
 In modern mills, the breast is lined with a cast-iron plate, 
 but we do not approve of this, because it is next to impossible 
 to prevent some small leakage of water through the masonry | 
 and this water, being confined behind the iron breast, cannot 
 escape, but its hydrostatic pressure to force up the iron is 
 enormous ; and if the water can ever insinuate itself behind 
 the whole surface of the plate, rarely fails to break it, if notj 
 to blow it up altogether. This is best guarded against by 
 making deep ribs projecting from the back of the plate, and 
 bedding them with great care in the masonry; these notj 
 only strengthen the plate, but also cut off the communication' 
 
AND MACHINIST. 
 
 105 
 
 of the water, so that it cannot act upon larger surfaces at 
 once, than the strength and weight of the plate can resist. 
 Stone is undoubtedly the best materials for a breasting. In 
 overshot-wheels the loss of water, by running out of the 
 buckets as they approach the bottom of the wheel, may be 
 considerably diminished by accurately forming a sweep or 
 casing round the lower portion of the wheel, so as to prevent 
 the immediate escape of the water, and causing it to act in 
 the manner of a breast-wheel. While this improvement 
 remains in good condition, and the wheel. works truly, it 
 produces a very sensible effect; but it is frequently objected 
 to, because a stick or a stone falling into the wheel would 
 be liable to tear off part of its shrouding, and damage the 
 buckets ; and again, a hard frost frequently binds all fast, 
 and totally prevents the possibility of working during its 
 continuance ; but we do not think the latter a great objection, 
 for the water is not more liable to freeze there than in the 
 buckets, or in the shuttle, and may be prevented by the same 
 means, viz. by keeping the wheel always in motion, a very 
 small stream of water left running all night will be sufficient. 
 Mr. Smeaton always used such sweeps, and with very good 
 effect ; it is certainly preferable to any intricate work in tiie 
 form of the buckets. 
 
 Mill-courses. — i\s it is of the highest importance to have 
 the height of the fall as great as possible, the bottom of the 
 canal or dam which conducts the water from the river should 
 have a very small declivity ; for the height of the water-fall 
 will diminish in proportion as the declivity of the canal is 
 increased ; on this account, it will be sufficient to make A B, 
 fig. 100, slope about one inch in 200 yards, taking care to 
 make the declivity about half an inch for the first 48 yards, 
 in order that the water may have a velocity sufficient to pre- 
 vent it from flowing back into the river. The inclination of 
 the fall, represented by the angle G C R, should be 25° 50' ; 
 or C R, the radius, should be to G R, the tangent of this 
 angle, as 100 to 48, or as 25 to 12 ; and since the surface 
 of the water S Z> is bent from a h into a c, before it is pre- 
 cipitated down the fall, it will be necessary to incurvate the 
 upper part B C D of the course into B D, that the water at 
 the bottom may move parallel to the water at the top of the 
 stream. For this purpose, take the points B, D, about 
 12 inches distant from C, and raise the perpendiculars B E, 
 D E ; the point of intersection E will be the centre, from 
 which the arch B D is to be described ; the radius being about 
 lOi^ inches. 
 
106 
 
 THE OPERATIVE MECKAMC 
 
 Now, ill order that the w^ater may act more advantageously 
 upon the float-boards of the wheel W W, it must assume a 
 horizontal direction H K, with the same velocity which it 
 would have acquired when it came to the point G : but, in 
 falling from C to G, the water will dash upon the horizontal 
 part H G, and thus lose a great part of its velocity ; it will 
 be proper, therefore, to make it move along F H, an arch of 
 a circle, to which D F and K H are tangents in the points F 
 and H. For this purpose, make GF and G H each equal to 
 three feet, and raise the perpendiculars HI, FI, which will 
 intersect one another in the points I, distant about four feet 
 nine inches and -rVths from the points F and H, and the 
 centre of the arch F II will be determined. The distance 
 H K, through which the water runs before it acts upon the 
 wheel, should not be less than two or three feet, in order that 
 the different portions of the fluid may have obtained a hori- 
 zontal direction ; and if H K be much larger, the velocity of 
 the stream would be diminished by its friction on the bottom 
 of the course. That no water may escape between the bot- 
 tom of the course K H and the extremities of the float- 
 boards, K L should be about three inches, and the extremity 
 o of the float-board o, should be beneath the line H K X, 
 suflicient room being left between o and M for the play of 
 the wheel, or K L M may be formed into the arch of a circle 
 K M, concentric with the wheel. The line L M V, called 
 by M. Fabre the course of impulsion, (le coursier d’impulsion,) 
 should be prolonged, so as to support the water as long as it if: 
 can act upon the float-boards, and should be about nine « 
 inches distant from O P, a horizontal line passing through O, 
 the lowest point of the fall ; for if O L were much less than^ 
 nine inches, the water, having spent the greater part of its^^ 
 force in impelling the float-boards, would accumulate below^j 
 the wheel and retard its motion. For the same reason, an-jH 
 other course, which is called by M. Fabre the course of dis-^B 
 charge, (le coursier de decharge,) should be connected with^H 
 L M V by the curve V N, to preserve the remaining velocitylH 
 of the water, which would otherwise be destroyed by falling.^; I 
 perpendicular from V to N. The course of discharge is re-||^ 
 presented by V Z, sloping from the point O. It should be*i' ^ 
 about 16 yards long, having an inch of declivity in every twoS [ 
 yards. The canal, w^hich reconducts the water from the.f, ^ 
 course of discharge to the river, should slope about four ‘ 
 inches in the first 200 yards, three inches in the second 200 .. j 
 yards, decreasing gradually till it terminates in the river. Butjf J 
 if the river, to wdiich the water is conveyed, should, whep' ^ 
 
AND MACHINIST. 
 
 107 
 
 swollen by the rains, force the water back upon the wheel, the 
 canal must have a greater declivity, in order to prevent this from 
 taking place. Hence it will be evident, that very accurate level- 
 ling is necessary for the proper formation of the mill-course. 
 
 ON SETTING OUT WATER-COURSES AND DAMS. 
 
 The most ancient mills were undershot-wheels placed in 
 the current of an open river, the building containing the mill 
 being set upon piles in the river. It would soon be observed 
 that the power of the mill would be greatly increased if all the 
 water of the river was concentrated to the wheel, by making an 
 obstruction across the river which penned up the water to a 
 required height; and also to form a pool or reservoir of water. 
 A sluice or shuttle would then become necessary to regulate 
 the admission of water to the wheel, and other sluices would 
 be necessary to allow the water to escape in times of floods ; 
 for though in ordinary times the water would run over the 
 top of the obstruction or dam, yet a very great body of water 
 running over might carry away the whole work, by washing 
 away the earth at the foot of the dam, and then overturning 
 it into the excavation. This is an accident which frequently 
 happens to milk so situated; and the dangei is so obvious, 
 that most water-mills are now removed to the side of the 
 river, and a channel is dug from the river to the mill to 
 supply it with water, and another to return the water from 
 the mill to the river. The difference of level between these 
 two channels is the fail of water to work the mill, and this is 
 kept up by means of a wear or dam entirely across the river, 
 but the water can run freely over this dam in case of floods, 
 without at all affecting the mill, because the entrance to the 
 channel of supply is regulated by sluices and side walls. 
 
 The dam should be erected across the river at a broad 
 part, where it will pen up the water so as to form a large 
 pond or reservoir, which is called the mill-pond or dam-head. 
 This reservoir is useful to gather the water which comes 
 down the river in the night, and reserve it for the next day’s 
 consumption : or for such mills as do not work incessantly, 
 but which require more water, when they do work, than the 
 ordinary stream of the river can supply in the same time. 
 The larger the surface of the pond is, the more efficient it 
 will be, but depth will not compensate for the want of 
 surface, because, as the surface sinks, when the water is 
 drawn off^ the fall on descent of the water, and consequently 
 the power of the water, diminishes. 
 
 The dam for a large river should be constructed with the 
 
108 
 
 THE OPERATIVE MECHANIC 
 
 utmost solidity; wood framing is very commonly used, but 
 masonry is preferable. Great care must be taken, by driving 
 pile planking under the dam, to intercept all .leakage of the 
 water beneath the ground under the dam, as that loosens the 
 earth, and destroys the foundation imperceptibly, when a 
 violent flood may overthrow the whole. It is a common 
 practice to place the dam obliquely across the river, with a 
 view of obtaining a greater length of wall for the water to run 
 over, and consequently prevent its rising to so great a height, 
 in order to give vent to the water of a flood. But this is 
 very objectionable, because the current of water constantly 
 running over the dam, always acts upon the shore or bank of 
 the river at one point, and will in time wear it away, if not 
 prevented by expensive works. This difficulty is obviated 
 by making the dam in two lengths which meet in an angle >, 
 the vertex pointing up the stream. In this way the currents 
 of water, coming from the two opposite parts of the dam, 
 strike together, and spend their force upon each other, 
 without injuring any part. A still better form is a segment 
 of a circle, which has the additional advantage of strength, 5|j 
 because if the abutments at the banks of the river are ^ j 
 firm, the whole dam becomes like the arch of a bridge laidJ? ' 
 down horizontally. This was the form generally used bv'^ ' 
 Mr. Smeaton. 
 
 The foot of the dam -where the water runs down should be 
 a regular slope with a curve, so as to lead the water down 
 regularly; and this part should be evenly paved with stone, 
 or planked, to prevent the -s^^ater from tearing it up when it 
 moves with a great velocity. » 
 
 When the fall is considerable, it may be divided into more 
 than one dam ; and if the lower dam is made to pen the water ^ 
 upon the foot of the higher dam, then the water running 
 over the higher dam, will strike into the water, and lose its 
 force. There is nothing can so soon exhaust the force of 
 rapid currents of water as to fall into other water, because 
 its mechanical force is expended in changing the figure of 
 the water ; but when it fails upon stone or wood, its force is 
 not taken away, but only reflected to some other part of the 
 channel, and may be made to act upon such a great extent of 
 surface as to do no very striking injury at any one time ; but ] 
 by degrees it wears away the banks, and requires constants]^, 
 repairs : for. it is demonstrable that, as much of the force of 
 the water as is not carried away by the rapid motion with ^ 
 which it flows, after passing the dam, must be expended^ 
 either in changing the figure of the water, or in washing ‘ 
 
AND MACHINIST. 109 
 
 away the banks, or in the friction of the water running over 
 the bottom. 
 
 The cotton- works of Messrs. Strutt, at Belper, in Derby- 
 shire, are on a large scale, and the most complete we have 
 evei'* seen, in their dams and water-works. The mills are 
 turned by the water of the river Derwent, which is very 
 subject to floods. The great wear is a semicircle, built of 
 very substantial masonry, and provided with a pool of water 
 below it, into which the water falls. On one side of the 
 wear are three sluices, each 20 feet wide, which are drawn 
 up in floods, and allow the water to pass sideways into the 
 same pool ; and on the opposite side is another such sluice, 
 22 feet wide. The water is retained in the lower pool by 
 some obstruction which it experiences in running beneath 
 the arches of a bridge; but the principal fall of the water is 
 broken by falling into the water of the pool, beneath the 
 great semicircular wear. 
 
 The water which is drawn off from the mill-dam above 
 the wear, passes through three sluices, 20 feet wide each, and 
 is then distributed by different channels to the mills, which 
 are situated at the side of the river, and quite secure from 
 all floods. There are six large water-wheels; one of them, 
 which is 40 feet in breadth, we have mentioned, from the 
 ingenuity of its construction ; and another, which is made in 
 two breadths of 15 feet each, we have also described. They 
 are all breast-wheels. The iron-works of Messrs. Walker, 
 at Rotherham, in Yorkshire, are very good specimens of 
 water-works; as also the Carron- works in Scotland. — Dr. 
 Rees's Cyclopcedia and Dr.- Brewster's Ferguson, 
 
 PENSTOCK, 
 
 The following is a description of a pentrough and stock for 
 equalizing the water falling on water-wheels, by Mr. Quayle. 
 
 To ensure a regular supply of w^ater on the wheel, and to 
 obviate the inconveniencies arising from the usual mode of 
 delivering it from the bottom of the pentrough, this method 
 is devised of regulating the quantity delivered by a float, and 
 taking the whole of the water from the surface. 
 
 Section of the pentrough. Fig. 99. A, the entrance of the 
 water; B, the float, having a circular aperture in the centre, 
 in which is suspended C, a cylinder, running down in the case 
 E below the bottom of the pentrough. This is made water- 
 tight at the bottom of the pentrough at F, by a leather collai* 
 placed between two plates, and screwed down to the bottom. 
 
 The cylinder is secured to the float so as to follow its rise 
 
110 
 
 THE OPERATIVE MECHANIC 
 
 and fall ; and the water is admitted into it through the opening 
 in its sides, and there, passing through the box or case E, 
 rises and issues at G on the wheel. By this means, a uniform 
 quantity of water is obtained at G ; which quantity can be 
 increased oi diminished by the assistance of a small rack 
 and pinion attached to the cylinder, which will raise or 
 depress the cylinder above or under the water line of the 
 float; and, by raising it up to the top, it stops the water 
 entirely, and answers the purpose of the common shuttle. 
 This pinion is turned by the handle H, similar to a winch- 
 handle; and is secured from running down by a ratchet- 
 wheel at the opposite end of the pinion axis. 
 
 K and L are two upright rods to preserve the perpendicular 
 rise and sinking of the float, running through the float, and 
 secured at the top by brackets from the sides. 
 
 M, a board let down across the pentrough nearly to the 
 bottom, to prevent the horizontal impulse of the water from 
 disturbing the float. 
 
 Fig. 99*. A transverse section, showing the mode of 
 fixing the rack and pinion, and their supports on the float. 
 The rack is inserted into a piece of metal running across the 
 cylinder near the top. That the water may pass more freely 
 when nearly exhausted, the bottom of the cylinder is not a 
 plane, but is cut away so as to leave two feet, as at C, 
 fig. 99. The float is also kept from lying on the pentrough 
 bottom by four small feet ; so that the water gets under it 
 regularly from the first. 
 
 Fig. 99**;, An enlarged view of the cylinder, showing the 
 rack and ratchet-wheel, with the clink, and one of the openings 
 on the side of the cylinder ; the winch or handle being on the 
 opposite side, and the pinion, by which the rack is raised, 
 enclosed in a box between them. 
 
 MR. SMEATON^S PENTROUGH. 
 
 Fig. 93*. G represents the pentrough through which the 
 water flows, and F F strong cross-beams on which it is sup- 
 ported ; the wheel is situated very close beneath the bottom of 
 the trough, as the figure shows. E E are two arms of the 
 wheel, which are put together, as shown in fig. 110. B D is 
 the wooden rim of the wheel; the narrow circle beyond this is 
 the section of the sole planking, and on the outside of this the 
 bucket-boards are fixed as the figure shows ; one of the bottom- 
 boards, b, of the trough at the end is inclined, and an opening 
 is left between that end and the other boards of the bottom, to 
 let the water pass through ; this opening is closed by a sliding 
 
AND MACHINIST. 
 
 HI 
 
 shuttle, c, which is fitted to the bottom of the trough, and 
 can be moved backwards and forwards by a rod d, and 
 lever e, which is fixed into a strong axis f; this axis has a 
 long lever on the end, which, being moved by the miller, 
 draws the shuttle along the bottom of the trough, and 
 increases or diminishes the aperture through which the 
 water issues. The extreme edge of the shuttle is cut 
 inclined, to make it correspond with the inclined part h, 
 and by this means it opens a parallel passage for the 
 water to run through, and this causes the w’ater to be 
 delivered in a regular and even sheet; and to contribute to 
 this the edges of the aperture where the water quits it are 
 rendered sharp by iron plates; the shuttle is made tight 
 where it lies upon the bottom of the trough, by leather, so as 
 to avoid any leakage -when the shuttle is closed. When the 
 wheel is of considerable breadth, the weight of the water 
 might bend down the middle of the trough until it touched 
 the wheel; to prevent this, a strong beam, O, is placed across 
 the trough, and the trough is suspended from this by iron 
 bolts which pass through grooves in the shuttle, so that they 
 do not interfere with the motion of the shuttle. 
 
 Mr, Nouaille took out a patent, in October, 1812, for a 
 new method of laying water upon an overshot-W’heel, (see 
 fig. 94,) which he thus describes : — In my new method of 
 applying water to water-wheels, I cause it to commence its 
 action upon a point of the wheel’s circumference, which is 
 about 53 degrees distant from the vertex, or the highest point 
 thereof, instead of applying it at the top of the wheel, as hereto- 
 fore commonh practised for overshot- w^heels. By these means 
 1 can have the advantages of a large wheel in situations where 
 the fall would only allow of a smaller, if the water was applied 
 at the top ; thus, if there be a perpendicular of 1 2 feet, I cause 
 a wheel of 15 feet diameter to be made, and of course the 
 water must be made to act upon it at a height of 12 feet, 
 which is three feet perpendicular below the top of the wheel, 
 and at about 53 degrees from the top, measured round its 
 circumference as above stated. I make the pentrough which 
 brings the water to the wheel of such a form that it delivers 
 the water from the bottom of it through the floor, and is 
 directed at such an angle as to fall into the buckets nearly 
 in the direction of the wheel’s motion, which will be at an 
 angle of 75 degrees with the horizon ; the shuttle or gate 
 slides upon the floor of the trough, so as to cover the aperture, 
 and determine the quardity of water to be let out upon the 
 wheel. 
 
112 
 
 THE OPERATIVE MECHANIC 
 
 The exact manner of carrying this principle into effect is 
 particularly explained by the annexed draft, which is a vertical 
 section of a water-wheel on my improved plan. In this the 
 dotted line A A, fig. 116, represents the level of the water 
 at its full head, and B the level of the tail- water ; therefore 
 A B is the extreme fall, A C is the depth of the water in the 
 pentrough. Now, instead of the common practice of making 
 a wheel of the diameter equal to B C, 1 make the wheel 
 D E F G one-fourth larger than B C, then the water will be 
 delivered upon it at the point E. The floor C of the pen- 
 trough C H Lj does not come up to meet the end H thereof, 
 but leaves a small space through which the water issues in 
 the direction of the dotted line 1 1, to the buckets of the 
 wheel. The breadth of this space is determined by the 
 shuttle K, which lays flat upon the floor of the pentrough, 
 and slides over the aperture. It is regulated by means of a 
 lever N, acted upon by a screw, rack, or other adjustment, at 
 M, and the water is thus delivered in a very thin and regular 
 sheet into the buckets."’ 
 
 Fig. 117 represents a method of laying on water which 
 has for several years been in common use in Yorkshire and 
 the north of England. In this the water is hot applied quite 
 at the top of the wheel, but nearly in the same position as 
 the last described; but the advantages of this wheel over all 
 others is, that the water can be delivered at a greater or less 
 height, according to the height at which the water stands in 
 the trough ; but in all the preceding methods, if the water is 
 subject to variations of height, as all rivers are, then the 
 wheel must be diminished, so that in the lowest state of the 
 water it will stand a sufficient depth above the orifice in the 
 bottom of the trough to issue with a velocity rather greater 
 than the motion of the wheel. In this case, when the water 
 rises to its usual height, or above it, the increase of fall thus 
 obtained is very little advantage to the wheel ; the improved 
 wheel can at all times take the utmost fall of the water, even 
 when its height varies from three to four feet. A A is the 
 pentrough made of cast-iron; the end of it is formed by a 
 grating of broad flat iron bars, which are inclined in the 
 proper position to direct the water through them into the 
 buckets of the wheel. The spaces between the bars are shut 
 up by a large sheet of leather, which is made fast to the 
 bottom of the iron trough at a, and is applied against the 
 bars ; and the pressure of the water keeps it in close contact 
 with the bars, so as to prevent any leakage. This is the 
 real shuttle, and to open it so as to give the required stream 
 
'Wbi:ekls 
 
 Fiom 109 to I'll 
 
 n.ii. 
 
 \ 
 
 yotU'Jh Jtr/md 
 
AND MACHINIST. 
 
 113 
 
 of water to the wheels the upper edge of the leather is 
 wrapped round a smaller roller^ h ; the pivots at the ends of 
 this roller are received in the lower ends of tw’o racks, which 
 are made to slide up and doum by the action of two pinions 
 fixed upon a common axis which extends across the trough ; 
 this axis being turned, raises up or lowers down the roller, 
 and the leather shuttle winds upon it as it descends, or 
 unwinds from it as it ascends, so as to open more of the 
 spaces between the bars, or close them, as it is required. In 
 order to make the roller take up the leather, and always draw 
 it tight, a strap of leather is wound round the extreme ends 
 of the rgllers, beyond the part w'here the leather shuttle rolls 
 upon it. These straps are carried above water and applied on 
 wheels, which Mind them up with a very considerable tension, 
 by the action of a band and weight wrapped on the circum- 
 ference of a wheel, which is on the end of the axis of those 
 wheels. 
 
 The water runs over the upper side of the roller, and flows 
 through the spaces between the grating into the buckets of 
 the wheel; the descent of the water passing through the 
 bars, and afterwards in falling before it strikes the bottom 
 of the bucket, is found fully sufficient to produce the neces- 
 sary velocity of the water, for a fall cd four inches produces 
 a velocity of more than four feet per second. 
 
 We recommend this as the best method of applying the 
 water, as we see in all other forms that a much greater 
 portion of the fall is given up in order to make the water 
 flow into the wheel; not that any such depth as is commonlv 
 given is at all necessaiy, but the aperture in the trough 
 must be placed so low that the water will run through it in 
 the very low’est states of the water, otherwise the wheel 
 must stop at such times. — Dr. Rees’s Cyclopcedia. Reper- 
 tory of Arts, 1813. 
 
 SLUICE GOVERNOR FOR REGULATING THE INTRODUCTION OF 
 WATER UPON WATER-WHEELS OF ALL KINDS. 
 
 The ingenious Mr. Burns actually constructed for the 
 Cartside Cotton Mills, the sluice governor, represented at 
 figs. 118, 119, 120, and 121, which was considered of such 
 advantage as to produce a saving of more than lOOf.per annum. 
 
 The motion of the w^ater- wheel is communicated bv a belt 
 or rope going round the pulley I to the axis E F* which 
 carries the balls G H, fig. 118. This motion is conveyed to 
 the upright shaft T, by the wheels and pinions Q, R, S, T, 
 and the v heel N at the bottom of the shaft drives the wheels 
 
 1 
 
114 THE OPERATIVE MECHANIC 
 
 P, figs. 119 and 120, in opposite directions. When the 
 velocity of the wheel is such as is required, the wheels O, P 
 move loosely about the axis, and carry the motion no farther. 
 But when the velocity of the wheel is too great, the balls 
 G, H, separated by the increase of centrifugal force, raise 
 the box a upon the shaft E F. An iron cross h c, see fig. 121, 
 is fitted into the box «. This cross works in the four prongs 
 of the fork eb c, fig. 1 19, at the end of the lever dqfe, which 
 moves horizontally round / as its centre of motion. When 
 the box a is stationary, which is when the wheel has its 
 proper velocity, the iron cross works within two of the 
 prongs so as not to affect the lever afc, but to allow the 
 clutch q q, fixed at the end of the lever, to be disengaged 
 from the wheels. When the cross be rises, it strikes in 
 turning round the prong 3, see fig. 121, which drives aside the 
 lever efa, and throws the clutch q into the arms of the 
 wheel P, figs. 119, 120. This causes it to drive round the shaft 
 DC in one direction. When the iron cross b c, on the 
 contrary, is depressed by any diminution in the velocity of 
 the wheel, it strikes in turning round the prong 4, which 
 pushes aside the lever efd, and throws the clutch q into the 
 wheel O. This causes the wheel O to drive the sWt in an 
 opposite direction to that in which it was driven by P. 
 Now the shaft D C, which is thus put in motion, drives, by 
 means of the pinion C and wheel B, the inclined shaft B W, 
 which, by an endless screw, X, working in the toothed 
 quadrant Z, elevates or depresses the sluice K L, and admits 
 a greater or a less quantity of water, according to the motion 
 given to the shaft by the wheel P or O. This change in 
 the aperture is produced very gradually, as the train of wheel- 
 work is made so as to reduce the motion at the sluice. The 
 centre in which the sluice turns should be one-third of its 
 height from the bottom, in order that the pressure of the 
 water on the part above the centre may balance the pressure 
 on the part below the centre. 
 
 MR. FERGUSOT^’s RULES FOR THE CONSTRUCTION OF 
 UNDERSHOT WATER-MILLS. 
 
 When the float-boards of the water-wheel move with 
 a third part of the velocity of the water that acts upon them, ■ 
 the water has the greatest power to turn the mill : and when ' 
 the mill-stone makes about 60 revolutions in a minute, it is^^ ; 
 found to do its work the best. For, when it makes but i 
 
 about 40 or 50 it grinds too slowly, and when it makes more ! 
 
 than 70 , it heats the meal too much, and cuts the bran so ? 
 
AND MACHINIST. 
 
 115 
 
 small, that a great part thereof mixes with the meal, and 
 cannot be separated from it by sifting or boiilting. Conse- 
 quently, the utmost perfection of mill-work lies in making 
 the train so, as that the mill-stone shall make about 60 turns 
 in a minute when the water-wheel moves with a third part 
 of the velocity of the water. To have it so, observe the 
 following rules : 
 
 1. Measure the perpendicular height of the fall of water, 
 in feet, above the middle of the aperture, where it is let out 
 to act by impulse against the float-boards on the lowest side 
 of the undershot-wheel. 
 
 2. Multiply this constant number 64.2882, by the height 
 of the fall in feet, and extract the square root of the product, 
 which shall be the velocity of the water at the bottom of the 
 fall, or the number of feet the water moves per second. 
 
 3. Divide the velocity of the water by 3, and the quotient 
 shall be the velocity of the floats of the wheel, in feet, per 
 second. 
 
 4. Divide the circumference of the wheel in feet, by the 
 velocity of its floats, and the quotient will be the number of 
 seconds in one turn or revolution of the great water-wheel 
 on whose axis the cog-wheel that turns the trundle is fixed. 
 
 5. Divide 60 by the number of seconds in a turn of the 
 water-wheel, or cog-wheel, and the quotient will be the 
 number of turns of either of these wheels in a minute. 
 
 6. By this number of turns divide 60, (the number of turns 
 the mill-stone ought to have in a minute,) and the quotient 
 will be the number of turns the mill-stone ought to have for 
 one turn of the water or cog wheel. Then, 
 
 7. As the required number of turns of the mill-stone in a 
 minute is to the number of turns of the cog-wheel in a 
 minute, so must the number of cogs in the wheel be to the 
 number of staves in the trundle on the axis of the mill- stone, 
 in the nearest whole number that can be found. By these 
 rules the following table is calculated ; in which the diameter 
 of the water-wheel is supposed to be 18 feet, (and conse- 
 quently its circumference 56|- feet,) and the distance of the 
 mill-stone to be five feet. • 
 
IIG 
 
 THE OPERATIVE MECHANIC 
 
 Perpendicular height of 
 the fall of water in feet. 
 
 Velocity of the water, in 
 feet, per second. 
 
 Velocity of the wheel, in 
 feet, per second. 
 
 Number of turns of the 
 wheel in a minute. 
 
 Required number of turns 
 of the rnill-stones for 
 each turn of the Avheel. 
 
 Nearest number of cogs 
 and staves for that 
 
 purpose. 
 
 Number of turns of the 
 mill-stone for one turn 1 
 of the wheel by these i 
 cogs and staves. | 
 
 Number of turns of the 
 mill-stone in a minute 
 by these cogs and 
 staves. 
 
 1 
 
 8-02 
 
 2*67 
 
 2-63 
 
 21*20 
 
 Coes. Staves. 
 
 127 6 
 
 21*17 
 
 59*91 
 
 2 
 
 11*40 
 
 3*72 
 
 4-00 
 
 15-00 
 
 105 
 
 7 
 
 15-00 
 
 60-00 
 
 3 
 
 13-89 
 
 4*63 
 
 4-91 
 
 12-22 
 
 98 
 
 8 
 
 12-25 
 
 60-14 
 
 4 
 
 16*04 
 
 5*35 
 
 5*67 
 
 10-58 
 
 95 
 
 9 
 
 10-56 
 
 59-87 
 
 5 
 
 17-93 
 
 5*98 
 
 6*34 
 
 9*46 
 
 85 
 
 9 
 
 9*44 
 
 59-84 
 
 6 
 
 19-64 
 
 6*55 
 
 6*94 
 
 8-64 
 
 78 
 
 9 
 
 8*66 
 
 60-10 
 
 7 
 
 21-21 
 
 7-07 
 
 7-50 
 
 8-00 
 
 72 
 
 9 
 
 8*00 
 
 6000 
 
 8 
 
 22-68 
 
 7-56 
 
 8-02 
 
 7-48 
 
 67 
 
 9 
 
 7-44 
 
 59-67 
 
 9 
 
 24*05 
 
 8-02 
 
 8 51 
 
 7-05 
 
 70 
 
 10 
 
 7-00 
 
 59-57 
 
 10 
 
 25*35 
 
 8-45 
 
 8-97 
 
 6*69 
 
 67 
 
 10 
 
 6-70 
 
 6009 
 
 11 
 
 26*59 
 
 8*86 
 
 9-40 
 
 6*38 
 
 64 
 
 10 
 
 6-40 
 
 60*16 
 
 12 
 
 27-77 
 
 9*26 
 
 9*82 
 
 6*11 
 
 61 
 
 10 
 
 6*10 
 
 69*90 
 
 13 
 
 28-91 
 
 9*64 
 
 10-22 
 
 5*87 
 
 59 
 
 10 
 
 5*90 
 
 60-18 
 
 14 
 
 30-00 
 
 1000 
 
 10-60 
 
 5-66 
 
 56 
 
 10 
 
 5-60 
 
 59*36 
 
 15 
 
 31*05 
 
 1035 
 
 10-99 
 
 5*46 
 
 55 
 
 10 
 
 5*40 
 
 50*48 
 
 lo- 
 
 32-07 
 
 10-69 
 
 11*34 
 
 5-29 
 
 53 
 
 10 
 
 5*30 
 
 60*10 , 
 
 ir 
 
 33-06 
 
 11*02 
 
 11-70 
 
 5-13 
 
 51 
 
 10 
 
 5*10 
 
 59*67 . 
 
 18 
 
 34-12 
 
 11*34 
 
 12-02 
 
 4*90 
 
 50 
 
 10 
 
 5-00 
 
 60*10 
 
 19 
 
 34*95 
 
 11-65 
 
 12-37 
 
 4-85 
 
 49 
 
 10 
 
 4-80 
 
 60-61 
 
 20 
 
 35*86 
 
 11-92 
 
 12-68 
 
 4*73 
 
 47 
 
 10 
 
 4-70 
 
 .59-59 : 
 
 1 
 
 2 
 
 1 
 
 3 
 
 4 
 
 5 
 
 e 
 
 
 7 
 
 B J 
 
 Fjxample , — Suppose an undershot-mill is to be built where ' J 
 the perpendicular height of the fall of water is nine feet ; it 
 is required to find how many cogs must be in the wheel, and h 
 how many staves in the trundle, to make the mill-stone go E 
 about 60 times round in a minute, while water-wheel floats 
 move with a third part of the velocity with which the 
 water spouts against them from the aperture at the bottom ofai i 
 the fall. 
 
 Find 9 (the height of the fall) in the first column of the 
 table ; then against that number, in the sixth column, is 7^ 
 for the number of cogs in the wheel, and 10 for the number 
 of staves in the trundle ; and by these numbers we find in 
 
AND MACHINIST. 
 
 U7 
 
 the eighth column that the mill- stone will make 59 turns 
 in a minute, which is within half a turn of 60, and near enough 
 for the purpose ; as it is not absolutely requisite that there 
 should be just 60 without any fraction : and throughout the 
 whole table the number of turns is not quite one more or 
 less than 60. 
 
 The diameter of the wheel being 18 feet, and the fall of 
 water nine feet, the second column shows the velocity of 
 the water at the bottom of the fall to be 24 t feet per 
 second ; the third column the velocity of the float-boards of 
 the wheel to be 8 t^it feet per second ; the fourth column shows 
 that the wheel will make 8-rW turns in a minute ; and the 
 sixth column shows that for the ^nill- stone to make exactly 
 60 turns in a minute, it ought to make 7 tw (or seven turns 
 and one-twentieth part of a turn) for one tu>rn of the wheel. 
 
 Dr. Brewster, in the valuable Appendix which he has 
 annexed to his edition of Mr. Ferguson’s works, shows, that 
 the principles upon which the above table is calculated, are 
 erroneous, owing to the author having, with Desagulier and 
 Maclaurin, embraced M. Parent’s theory, which Mr. Smeaton, 
 by repeated experiments, proved to be incorrect. 
 
 The constant number used by Mr. Ferguson for finding 
 the velocity of the water from the height of the fall, 64.2882, 
 appears to be also wrong. For, from some recent experi- 
 ments made by Mr. Whitehurst on pendulums, it is found, 
 that a heavy body falls 16.087 feet in a second of time : 
 consequently the constant number should be 64.348. 
 
 Dr. Brewster then states, that in Mr. Ferguson’s table, 
 the velocity of the mill-stone is too small ; and Mr. Imison, 
 in correcting this mistake, has made the velocity too great. 
 From this circumstance, the Mill-wrights’ Table, as hitherto 
 published, is fundamentally erroneous, and is more calculated 
 to mislead than to direct the practical mechanic. Proceed- 
 ing, therefore, upon the practical deductions of Smeaton, as 
 confirmed by theory, and employing a more correct constant 
 number, and a more suitable velocity for the mill- stone, we 
 may construct a new Mill-wrights’ Table by the following 
 rules : 
 
 1 . Find the perpendicular height of the fall of water in 
 feet above the bottom of the mill-course, at K, (fig. 100,) 
 and having diminished this number by one-half of the 
 natural depth of the water at K, call that the height of the 
 fall. 
 
 2. Since bodies acquire a velocity of 32* 174 feet in a 
 second, by falling through 16'087 feet, and since the velocities 
 
118 
 
 THE OPERATIVE MECHANIC 
 
 of falling bodies are as the square roots of the heiglits through 
 which they fall, the square root of 16‘087 will be to the 
 square roots of the height of the fall, as 32’ 174 to a fourth 
 number, which will be the velocity of the water. '^Therefore 
 the velocity of the water may be always found by multiply- 
 ing 32*174 by the square root of the height of the fall, and 
 ^ dividing that product by the square root of 16*087. C)r it 
 may be found more easily by multiplying the height of the 
 fall by the constant number 64*348, and extracting the 
 square root of the product, which, abstracting the effects of 
 friction, will be the velocity of the water required. 
 
 3. Take one-half of the velocity of the water, and it will 
 be the velocity which must be given to the float-boards, or 
 the number of feet they must move through in a second, in 
 order that the greatest effect may be produced. 
 
 4. Divide the circumference of the wheel by the velocity 
 of its float-boards per second, and the quotient will be the 
 number of seconds in which the wheel revolves. 
 
 5. Divide 60 by this last number, and the quotient will 
 be the number of revolutions which the wheel performs in a 
 minute. Or the number of revolutions performed by the 
 wheel in a minute, may be found by multiplying the velocity 
 of the float-boards by 60, and dividing the product by the 
 circumference of the wheel, which in the jiresent case is 
 47*12. 
 
 6. Divide 90 (the number of revolutions which a mill-stone 
 five feet diameter should perform in a minute) by the number 
 of revolutions made by the wheel in a minute, and the 
 ([uotient will be the number of turns which the mill-stone 
 ought to make for one revolution of the wheel. 
 
 7. Then, as the number of revolutions of the wheel in a 
 minute is to the number of the revolutions of the mill-stones 
 in a minute, so must the number of staves in the trundle be 
 to the number of teeth in the wheel, in the nearest whole 
 numbers that can be found. 
 
 8. Multiply the number of revolutions performed by the 
 wheel in a minute, by the number of revolutions made by 
 the mill-stone for one of the wheel, and the product will be 
 the number of revolutions performed by the mill-stone in a 
 minute. 
 
 In this manner the following table has been calculated for 
 a water- wheel 15 feet in diameter, which is a good medium 
 si/e, the mill-stone being five feet in diameter, and revolving 
 90 times in a minute. 
 
AND MACHINIST. 
 
 119 
 
 DR. BREWSTER’S MILL-WRIGHTS’ TABLE. 
 
 In which the velocity of the wheel is three- sevenths of the velocity of 
 the water, and the ^ects of friction on the velocity of' the stream 
 reduced to computation. 
 
 Height of the fall of 
 water. 
 
 Velocity of the watei 
 per second, friction 
 being considered. 
 
 Velocity of the wheel 
 per second, being 3- 
 7ths that of the water. 
 
 Revolutions of the wheel 
 per minute, its diame- 
 ter being 1 5 feet. 
 
 Revolutions for mill- 
 stone, for one of the 
 wheel. 
 
 Teeth in the wheel, and 
 staves in the trundles. 
 
 Revolutions of the mill- 
 stones per minute by 
 these staves and teeth. 
 
 
 100 parts 
 Feet, of a 
 foot. 
 
 100 parts 
 
 100 parts 
 
 100 parts 
 
 
 100 parts 
 
 Feet. 
 
 Feet, of a 
 foot. 
 
 Rev, of a 
 rev. 
 
 Rev. of a 
 rev. 
 
 Teeth. Staves. 
 
 Rev. of a 
 rev. 
 
 1 
 
 7*62 
 
 3-27 
 
 4-16 
 
 21-63 
 
 130 6 
 
 89-98 
 
 2 
 
 10-77 
 
 4-62 
 
 5-88 
 
 15-31 
 
 92 6 
 
 90-02 
 
 3 
 
 13-20 
 
 566 
 
 7-20 
 
 12-5Q 
 
 100 8 
 
 90-00 
 
 4 
 
 15-24 
 
 6-53 
 
 8-32 
 
 10-81 
 
 97 9 
 
 89-94 
 
 5 
 
 1704 
 
 7-30 
 
 9-28 
 
 9-70 
 
 97 10 
 
 90-02 
 
 6 
 
 18-67 
 
 8-00 
 
 10-19 
 
 8-83 
 
 97 11 
 
 89-98 
 
 7 
 
 20-15 
 
 8-64 
 
 1099 
 
 8-19 
 
 90 11 
 
 90-01 
 
 8 
 
 21-56 
 
 9-24 
 
 11-76 
 
 7-65 
 
 84 11 
 
 89-96 
 
 9 
 
 22-86 
 
 9-80 
 
 12-47 
 
 7-22 
 
 72 10 
 
 90-03 
 
 10 
 
 24-10 
 
 10-33 
 
 13-15 
 
 6-84 
 
 82 12 
 
 89-95 
 
 11 
 
 25-27 
 
 10-83 
 
 1379 
 
 6-53 
 
 85 13 
 
 90-05 
 
 12 
 
 26-40 
 
 11-31 
 
 14-40 
 
 6-25 
 
 72 12 
 
 90-00 
 
 13 
 
 27-47 
 
 11-77 
 
 14-99 
 
 6-00 
 
 72 12 
 
 89-94 
 
 14 
 
 28-51 
 
 12-22 
 
 15-56 
 
 5-78 
 
 75 13 
 
 89-94 
 
 15 
 
 29 52 
 
 12-65 
 
 16-13 
 
 5-58 
 
 67 12 
 
 9001 
 
 16 
 
 3048 
 
 13-06 
 
 16-63 
 
 5-41 
 
 65 12 
 
 89-97 
 
 17 
 
 31-42 
 
 13-46 
 
 17*14 
 
 5-25 
 
 63 12 
 
 89-99 
 
 18 
 
 32-33 
 
 13-86 
 
 17-65 
 
 5-10 
 
 61 12 
 
 90-01 
 
 19 
 
 33-22 
 
 14-24 
 
 18-13 
 
 4-96 
 
 64 13 
 
 89-92 
 
 20 
 
 34-17 
 
 14-64 
 
 18-64 
 
 4-83 
 
 58 12 
 
 89-84 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 i 
 
120 
 
 TllJi Ol'KRATIVK MECHANIC 
 
 TREATISES ON MILL -WORK. 
 
 Kiinsliche abriss Allcrhand, Wasser, Wind-ross, und Hand-muhlcn, &c., 
 von Jacob, de Strada a Rosberg, 1617. 
 
 Georg. Christoph Luerncr Machina toreutica nov'a ; oder bcschreibung dcr 
 neu erfundenen Drehmuhlen, 1661. 
 
 T.hcatrum Machinaruiu Novum ; das ist, neu vermehrter Schauplatz der 
 Mecbanischen Kiinste, handelt von Allerhand, Wasser, Wind, Ross, Gevvicht 
 und Hand-muhlen, von Geo. And. Bocklern, 1661. 
 
 Contenta discursus Mechanic!, concernentis Descriptionem Optimae formea 
 Velorum liorizontalium pro usu Molaruin, nec non fundamentum inclinatorum 
 Velorum in Navibus, habita coram Societate Regia, a R. H. translata ex 
 Collectionibus Philosophicis M. Dec. num. 3, pa. 61, 1681. 
 
 Dissertatio Historica de Molis, quam prseside Joh. Phil. Treuer defend. 
 Jo. Tob. Miihlberger Ratisbonens Jenae, 1695. 
 
 Martin Marten’s Wiskundige beschouwinge der Wind of Wadermoolens, 
 vergeleken met die van den heer Johann Lulofs Amsterdam 1700. 
 
 Vollstilndige Miihlen-baukunst, von Leonhard Christoph. .Sturm, 1718: 
 
 Jacob Leopold’s Theatrum Machinarum Molinarum, folio, 1724, 1725. 
 
 Remarques sur les Aubes ou Palettes des Moulins, et autres Machines mues 
 par le Courant des Rivieres, par M. Pitot, Mem. Acad. Roy. Paris, 1729. 
 
 Joh. van Zyl Theatrum Machinarum Universale of Groot Algemeen, Moolen- 
 bock, &c., Amsterdam, 1734. 
 
 Jo. Cai'al. Totens Disser. de Machinis Molaribus optime construendis, Lugd. 
 Batav. 1734. 
 
 Kurze, aber Deutliche anweisung zur construction der Wind und Wasscr- 
 muhlen, von Gottfr. Kinderliug, 1735 
 
 Desagulier’s Experimental Philosophy, 2 vols. 4to. 1735, 1744. 
 
 Architecture Hydraulique, par M. Belidor, 4 vols. 4to. 1737 — 1753. 
 
 Mr. W. Anderson, F. R. S. Description of a Water-wheel for Mills. Phil. 
 Trans, vol. 44, 1746. 
 
 Leonh. Euleri, De Constructione aptissima Molarum alatarum disp. Nor. 
 Com. Acad. Petrop. tom. 4, 1752. 
 
 M^moire dans lequel on d^montre que I’Eau d’une Chute, destin(?e a faire 
 mouvoir quelque Moulin ou autre Machine, pent toujours produire beaucoup 
 plus d’effet en agissant par son poids qu’en agissant par son choc, ct que le 
 roues a pots qui tournent vite, relativement aux chutes et aux d^penses d’eau, 
 par M. de Pareieux, Acad. Roy. Paris, 1754. 
 
 Jo. Alberti Euleri Enodatio Questionis : quo modo vis Aquae aluisve fluidi 
 cum maximo lucro ad Molas circumagendas, aliavc opera perficienda impendi 
 possit, praemio a Societate Regia. Sci. Getting. 1754. 
 
 An experimental Inquiry concerning the Natural Powers of Wind and Water 
 to turn Mills and other Machines depending on Circular Motion, by Mr. J. 
 Snieaton, F. R. S. Phil. Trans. 1759. 
 
 This, and Mr. Smeaton’s other papers are republished with his Reports, 1313, 
 in 4to. 
 
 M^moire dans lequel on prouve que les Aubes de Roues mues par les courans 
 de grandes Rivieres feroient beaucoup plus d’etfet si elles ^toient inclin(^es 
 aux I'ayons, qu’elles ne font 4tant appliqu^es contre les rayons monies, comme 
 elles sont aux Moulins pendans et aux Moulins sur Bateaux qui sont sur les 
 Rivieres de Seine, de Marne, de Loire, &c. par M. de Pareieux. Mem. Acad. Roy. 
 Paris, 1759. 
 
 Joh. Albert Euler’s Abhandlung von der bewegung ebeD<>r Flaehen, wen sie 
 vom Winde Getrieben Werden, 1765. 
 
 Schauplatz des Mechanischen Miihlenbaues, Darinnen von Verschiedenen 
 lIand,Trett, Ross, Gewicht, Wasser, und Wind-muhlen Gehandelt Wird, durch 
 Johan Georg. Scopp. J. C. iter Theil, 1766. 
 
 Theatrum Machinarum Molarium, oder schauplatz dcr Miihlenbaukunst, 
 £iL der Neunte theil von des sel hrn Jac. Leopolds, Theatro Machinarum, vop 
 Joh. Mathias Beyern, 1767, 1788, 1802. 
 
AND MACHINIST. 121 
 
 A Memoir concerning the most advantageous Construction of Water-wheels, 
 &c. by Mr. Mallet of Geneva, Phil, Trans. 1767. 
 
 Momoire sur les Roues Hydrauliques, par M. le Chevalier de Borda, Mem, 
 Acad. Roy. Paris, 1767. 
 
 Kurzer unterricht, allerley arten von Wind und Wasser-miihlen auf di 
 vortheilhafteste weise zu erbauen, nebst einigen gedanker iiber die verbessening 
 des rkderwerks, an den Miihlen, von Joh. Konig, 1767. 
 
 G. G. Bischolf’s Beytriige zur Mathesis der Miihlen, 1767. 
 
 Determination gen^rale de I’EfFet des Roues mues par le Choc de PEau, par 
 M. I’Abbe Bossui, Mem. Acad. Roy. Paris, 1769. 
 
 Andreas Kaovenhofer, Deutliche abhandlung von den rildern der Wasser- 
 miihlen, und von dem einrandigeu werke der Schneidemiihlen, 1770. 
 
 Manuel du Meunier et du Charpentier des Moullns, redige parEdm.Bcquillet, 
 177.5. 
 
 Remarques sur les Moulins et autres Machines, ou PEau tombe en dessus 
 de la Roue, par M. Lambert, 
 
 Experiences et Remarques sur les Moulins que PEau meut par en bas dans 
 line Direction horizontale, par M. Lambert, 
 
 Remarques sur les Moulins et autres Machines, dont les Roues prenant 
 PEau a line certaine Hauteur, par M. Lambert. 
 
 (The three last articles are inserted in Mem. Acad. Roy. Berlin, 1775. 
 
 Ausfiihrliche erkliiruag der Vorschlage fiir die Liingere dauer de Muhlen- 
 werk, nebst ahnlichen gegenstander, in ein gesprilch verfasset, von Johann 
 Christian Fullmann Muhlenmeister, 1780. 
 
 Tratado de los Granos y Modo de Molelos con Economic de la Conservation 
 de Astos y de las Haidnas; escr. en Fr. par M. Bcguillet y extract, y trad, al 
 Cast, conalgun Notas y un Supplem. por Ph. Marescaulchi, Madrid, 1786. 
 
 Suite de PArchitecture Hydraulique, par M. Fabre, 1786. 
 
 M^moires sur les Moyens de perfectionner les Moulins, et la Mouture 
 tconomique, par C. Bucquet, 1786. 
 
 Manuel ou Vocabulaire des Moulins a Pot, a Amst., 1786. 
 
 Die Nothigsten Kenntnisse zur Anlegung, Beurtheilung, und Berechnung 
 der Wasser-miihlen, and zwar der Mahl, Oehl, und Siige-Muhlen, siir Anfanger 
 und Liebhaber der Miihlenbaukunst, von Joh. Christ. Huth, 1787. 
 
 ^\n Essay proving Iron far superior to Stone of any kind for breaking and 
 grinding of Corn, &c. by W. Walton, 1788. 
 
 Miihlenpraktik, oder unterrjcht in dem Mahlen der Brodfriichte, fiir Polizey- 
 bcainte, Gaverksleute und Hauswirthe, von L. Ph. Hahn, 1790. 
 
 The Young Miil-wright and Miller’s Guide, by Oliver Evans, Philadelphia, 
 1790. 
 
 Manuel du Meunier, et du Constructeur des Moulins a Eau et a Grains, par 
 C. Bucquet, 1791. 
 
 Praktische anweisung zura Miihlen bau, von Lr. Clausen, 1792. 
 
 Beschreibung zweir Machinen zur Reinigung des Korns, von Lr. Clausen, 
 1792. 
 
 Instructions sur PUsage des Moulins a Bras, invent6s et perfectionn^s par 
 les Citoyens Duraud, P^re et Fils, M^chaniciens, 1793. 
 
 Theoretisch-praktische abhandlung iiber die Besserung der Miihlrader, von 
 dem Vertasser der Zweckmilssigen, Luftreiniger, &c, 1795. 
 
 ATreatise ou Mills, in four parts, by John Banks, 1795. 
 
 Flandbuck der Maschinenlehre, sur prakiker und akademische lehrer, von 
 Karl Christian Lanpdorf, 1797, 1799. 
 
 On the Power ol Machines; including Barker’s Mill, Westgarth’s Engine, 
 Cooper’s Mill, Horizontal Water-wheel, Ac. by John Banks, 1803. 
 
 The Experienced Mill-wright, by Andrew Gray, Miil-wrigbt, 1804. 
 
 The i ransactions of the Society of Arts and Manufactures ; several of the 
 volumes of which contain improvements in Mill-work. 
 
 See also the Repertory of Arts, first series 16 vols. and second series 31 vols» 
 
 Hachetto, Traitb Eldmentaire des Machines, 4to. Paris, 1811, 
 
 Buchanan’s Essay on Mill-work, 1811, 8vo. 
 
122 
 
 THE OPERATIVE MECHANIC 
 
 WINDMILLS. 
 
 The windmill derives its name from the motion it receives 
 from the impulse of the wind. 
 
 The date of its invention is not precisely knowTi, though 
 authors generally concur in believing it to have taken place 
 at no very distant period of time. Some state it to have 
 been first used in France in the sixth century: others, on the 
 contrary, assert, that at the time of the crusades it was 
 introduced into Europe from the east, where scarcity of 
 water gave the impetus that led to its discovery. 
 
 Windmills are of two kinds, horizontal and vertical, 
 
 THE VERTICAL WINDMILL 
 
 Consists of a strong shaft, or axis, inclining a little upwards 
 from the horizon, with four long yards, or arms, fixed to the 
 highest end, perpendicular to the shaft, and crossing each 
 other at right angles. Into these arms are mortised several 
 small cross-bars, and to them are fastened two, three, or four, 
 long bars, running in a direction parallel with the length of 
 the arms; so that the bars intersect each other, and form a kind 
 of lattice work, on which a cloth is spread to receive the action 
 of wind. These are called the sails, and are in the shape 
 of a trapezium, usually about nine yards long and two wide. 
 
 As the direction of the wind is very uncertain, and 
 perpetually changing, it becomes necessary to have some 
 contrivance for bringing the wdndshaft and sails into a 
 position proper for receiving its impression. To effect this, 
 two methods are in general use : the one called the post-mill ; 
 the other the smock-mill. 
 
 post-mills. 
 
 In the post-mill it is accomplished by driving perpendicularly 
 into the earth the trunk of a strong tree, that is held securely 
 upright by several oblique braces, which extend from a 
 platform on the ground to the middle of the tree, leaving 10 
 or 12 feet of the upper part free from the braces. The part 
 thus left free from obstruction is rounded, and made to pass 
 through a circular collar, formed in the flooring of the lower 
 chamber, and to enter into a socket fixed into the flooring of 
 the upper chamber, and to one of the strongest cross-beams, 
 which must sustain the whole weight of the mill-house, so 
 that, by means of a pivot, or gudgeon, fastened on that part 
 of the post which enters into the socket, the whole machine 
 can turn about horizontally to face the wjnd. A strong 
 
AND MACHINIST, 
 
 123 
 
 framing, united .by joints to the back part of the mill-house, 
 descends in a sloping direction till it touches the ground; 
 the bottom of it is very heavy, and is fastened by cords to 
 some short posts that are driven in a circle, at regular intervals 
 round the mill, to prevent the mill from turning about at 
 every sudden squall. This framing is furnished with steps 
 to serve as a ladder of ascent or descent. At the bottom of 
 it a rope is fastened, and carried thence in an inclined position 
 to the top of the mill, where, by a lever or tackle of pullies, 
 it can be shortened so as to raise the framing from the 
 ground, and then by pushing against it, in the manner of a 
 lever, the whole mill may be turned in any required direction, 
 To obtain more force, a small capstan is often provided to 
 draw a rope fixed to the end of the ladder : this capstan is 
 movable, and can be fastened at pleasure to anyone of the posts. 
 
 The internal mechanism of a post-mill is exhibited in fig. 123. WXY 
 the upper chamber; X YZ the lower one; AB the shaft, or axis, with the 
 cog-wheel G, moving round in order of the letters that describe the sails 
 CDEF, giving motion to the lantern H, and its spindle IK; LM is a 
 bridge to support the said spindle ; and N and O P are beams to sustain 
 the bridge. The top mill-stone Q is the only one that moves, and is fixed 
 on the spindle I K by a piece of iron, called the rynd, let in at the lower 
 part of the stone ; the lower mill-stone R, is somewhat larger than the 
 other. The corn is put into the hopper S, and runs from thence along the 
 spout T ; the spindle I K, being square, shakes in its revolutions the 
 spout T, and causes the corn to fall through the hole V between the stones, 
 where it is ground ; the flour then passes through the tunnel a h, and is 
 finally deposited in the chest c ; c? e is a string going round the pin d, and 
 serving to draw the spout T nearer to, or farther from, the spindle I K, that 
 the corn may be made to run out either faster or slower, according to the 
 velocity of the wind ; fg and h i are levers, whose centres of motion are f 
 and m; i Z re p is a cord going about the pins I and re to wind up and raise 
 the stone Q. By bearing down the end rh, g is raised, which raises the 
 perpendicular N O, the perpendicular raises the cross-beam O P, the cross- 
 beam the bridge L M and the spindle 1 K, together with the upper mill- 
 stone Q, so that the stones can be set at any required distance apart. The 
 com is drawn up to the top of the mill by means of a rope rolled about the 
 .axis A B ; qr is a ladder for ascending to the higher part of the mill. A 
 girt or gripe of pliable w’ood is fixed at one end s, and at the other tied to 
 the lever tv, movable about at w, which being pressed down stops the 
 motion of the mill at pleasure. When the wind is great, the sails are only 
 in part, or on one side covered, and sometimes only one-half of two 
 , opposite sails. The same shaft can have another cog-wheel fixed to the 
 end B, with trundle and mill-stones similar to those already described: 
 by which means the shaft can turn two pair of stones at once ; and when 
 one pair only is wanted to grind, the lantern H and spindle I K are taken 
 out from the other. 
 
 SMOCK-MILL. 
 
 The other method of bringing the windshaft and sails into 
 A position proper for receiving the impression of the wind is, 
 
124 
 
 THE OPERATIVE MECHANIC 
 
 by what is called the smock-mill. This mill is more expen 
 sive in the construction^ and more decidedly advantageous, 
 as it can be made of any required dimensions. It is built in 
 the form of a round turret, having at the top of it a wooden 
 ring with a groove in it, furnished with a number of brass 
 truckles, kept equi-distant from each other by their centre 
 pins being fixed into a circular hoop. Into this groove the 
 framing of the upper or movable part of the mill, which is 
 called the head, or cap, enters, and a very slight power is 
 alone sufficient to turn it about that the sails may receive the 
 action of the wind. The head or cap is very ingeniously 
 contrived to turn itself about whenever the wind changes, 
 by a small pair of sails, or fans, fixed up in a frame that 
 projects from the back part of the head. 
 
 Fig. 124, a the fans, having on its axis a pinion of 10 leaves b, which 
 gives motion to a cog-wheel of 60 teeth c, its axis d, and a pinion of 
 12 teeth at the lower end e, turning a bevelled wheel of 72 teeth/, a vertical 
 iron shaft g, having a pinion of 11 teeth h, that works in a circle of 120 
 cogs. Therefore, whenever the wind changes, it acts obliquely upon the 
 vanes of the fan, and turns it round, which, giving an impulse to the 
 connecting machinery, brings the main shaft of the sails slowly about to face 
 the direction of the wind, llie method of this operation is as follows : the 
 fans, having received the action of the wind, turn round, and the pinion h of 
 10 leaves, that is upon its axis, gives motion to the cog-wheel of 60 teeth 
 c, fixed on an inclined axis which has at the lower end the pinion of 
 12 leaves e, acting upon the bevelled wheel of 72 teeth/, fixed on a vertical 
 iron axis, and giving motion to the pinion of 1 1 teeth A, that works in the 
 circle of 120 cogs. A B two of the sails (the other two being endwise 
 cannot be seen) fixed on an iron shaft or axis C D, by screwing them to 
 an iron cross formed at one end of it. Upon this shaft is the cog-wheel E, 
 that acts upon the lantern F, fixed on a strong vertical shaft extending from 
 the top to the bottom of the mill, and having on the lower end the large 
 wheel i i, giving motion to the two opposite pinions k k, which turn the 
 spindles and the mill-stones G H. A wheel is fixed on the main axis at I, 
 to give action to the pinion on the horizontal roller »n, which has a rope 
 wrapped about it to wind up the sacks of corn. The same wheel I turns 
 another horizontal axis that has several wheels to receive endless ropes for 
 turning the bolting and dressing machines. On the middle part of the 
 vertical shaft K L is the wheel 1, which turns the roller w. to draw up the 
 sacks of corn from the lower part of the mill, which is used as a storehouse ; 
 being divided into as many compartments as the miller may require. To 
 the mill-stone spindle is attached a pair of regulating balls, to regulate the 
 velocity of the mill. For the manner of applying this regulator see 
 rig. 125, Za spindle, on which is fixed the pinion k, playing into the large 
 wheel that is attached to the vertical shaft ; the lower end of the spindle 
 enters into a square formed on the top of the mill-stone axis at m ,* imme- 
 diately beneath the pinion two iron rods are jointed, bending downwards, 
 having a heavy iron ball o o fastened to the end of each ; to these rods are 
 attached two links at pp, to suspend a collar capable of sliding freely up 
 and down upon the spindle 1; this collar is embraced by a fork, formed on 
 a steelyard, lying horizontal, and suspended by the fulcrum q ; r is an iron 
 i'od fixed at the extreme cud of the steelyard, and having at the bottom an 
 
Jmana 
 

AND MACHINIST. 
 
 125 
 
 iron hook to connect it with the lever s, whose fulcrum is t ; this, by means 
 of an iron rod, suspends one end of the bridge on which the lower pivot of 
 the mill-stone rests, the other end bearing on a fulcrum, or centre. 
 
 Whenever the mill acquires velocity, the iron balls, by their centrifugal 
 force, will fly out, and elevate the collar, which, acting upon the connecting 
 parts, will let the upper mill-Mone down nearer to the lower one, and the 
 resistance or friction thus caused will counteract the increased velocity of 
 the wind. On the contrary, if the wind decreases, the balls will fall 
 towards each other, and let down the sliding collar, which will raise the 
 top mill-stone, and by increasing the distance between it and the lower 
 one cause the mill to acquire greater velocity. For this purpose a weight v 
 is hung upon the steelyard, sufficient to raise the stone whenever the 
 descent of the collar will permit it so to do. Several notches are cut into 
 the steelyard for different positions of the fulcrum q and rod r, to regulate 
 more effectually the motion of the machinery. For instance, if the wind 
 should blow stronger, and the mill go slower, contrary to the effect expected, 
 it shows that the regulation is too strong : to remedy this, the leverage of the 
 balls must be increased by reducing the distance between the fulcrum q 
 and the rod r,by shifting either of them into different notches. On the other 
 hand, if the velocity of the mill should increase with the velocity of the 
 wind, it shows that the regulation is not strong enough, and that the 
 fulcrum q and the rod r must be set a greater distance apart. Sometimes 
 it happens that the whole limits of the notches on the steelyard is insuffi- 
 cient to effectuate the desired object ; in such case, the acting length of the 
 lever s s must be increased or diminished by removing the fulcrum i to a 
 greater or less distance from the suspended rod v. 
 
 ' In fig. 126 is shown the construction of the horizontal shaft or axis that 
 • bears the sails. It is an octagonal iron shaft, having two cylindrical necks, 
 c and d, where it rests upon its bearings. At the end it has a kind of box 
 which has two mortises, e and /, through it in perpendicular directions, to 
 receive the sails. At the back of one of these mortises, and the front of the 
 other, a projecting arm is left in the casting to receive screw bolts for 
 holding the sails secure in the mortises. The sails are braced to each arm 
 by a rope stay, proceeding from the end of a pole, fixed at the end of the 
 cast-iron axis. Each sail is formed of a sail cloth, spread upon a kind of 
 lattice work, similar to that described under the head of Post-mill. The 
 plane of this frame is inclined to the plane of the sail’s motion, at such an 
 angle, that the wind blowing in the direction of the axis acts upon the sails 
 as inclined planes, and turns them about with a power proportionate to the 
 size of the sails and the force of the wind. The cog-wheel is fixed on the 
 axis by bolting its arms against the stanch marked C. The mill-stones are 
 the same as those described under the head of Flour-mill. 
 
 Parent, Euler, and other geometricians have written much 
 upon the nature and construction of windmills; but as we 
 consider the experiments and researches made by our own 
 countryman Smeaton to be far superior in point of practical 
 utility, we shall content ourselves with giving his opinion 
 as to the shape, magnitude, and position of the sails. 
 
 By Mr. Smeaton’ s experiments it appears, that when the 
 sails were set at the angle of 55 degrees with the axis, 
 proposed as the best by M. Parent and others, they were the 
 most disadvantageous of any that were tried by him. 
 
!2G 
 
 THE OPERATIVE MECHANIC 
 
 On increasing the angle of the sails with the axis from J2 
 to 7^ degrees, an augmentation of power was produced in 
 the ratio of 31 to 45, and this proves to be the angle most 
 commonly in use when the surfaces of the sails are planes. 
 
 If nothing more were requisite than to make the mill 
 acquire motion from a state of rest, or to prevent it from 
 passing into rest from a state of motion, the position recom- 
 mended by M. Parent would be the best; but if the sails are 
 intended, with given directions, to jiroduce the greatest 
 effect possible in a given time, we must reject M. Parent’s 
 position; and, if use be made of planes, confine our angle 
 within the limits of 72 and Jb degrees with the axis. 
 
 The variation of a degree or two in the angle makes very little 
 difference in the effect, when the angle is near upon the best. 
 
 Mr. Smeaton made several experiments upon a large scale, 
 and found the following angles to answer as well as any^ 
 The radius is supposed to be divided into six parts, and one- 
 sixth, reckoning from the centre, is called one, the extremity 
 being denoted six. 
 
 No. 
 
 Angle with 
 the axis. 
 
 Angle with the 
 plane of the motion. 
 
 1 - - - 
 
 - - - 72'^ - 
 
 18 
 
 2 - - - 
 
 - - - 71 - 
 
 ----- 19 
 
 3 - - - 
 
 - - - 72 - 
 
 ----- 18 middle 
 
 4 _ _ - 
 
 - - - 74 - 
 
 16 
 
 5 - - - 
 
 - - - 77f - 
 
 m 
 
 6 - - - 
 
 - - - 83 - 
 
 ----- 7 extremity. 
 
 Having thus obtained the best position of the sails, or 
 manner of weathering, as it is called by the workmen^ 
 Mr. Smeaton next proceeded to try what advantage could be 
 made by an addition of surface upon the same radius. The 
 result was, that a broader sail requires a greater angle ; and 
 that when the sail is broader at the extremity than near the 
 centre, this shape is more advantageous than that of a 
 parallelogram. The figure and proportion of the enlarged 
 sails he found to answer best upon a large scale, where the 
 extreme bar is one-third of the radius, or whip, and is divided 
 by the whip in the proportion of 3 to 5. The triangular, or 
 leading sail, is covered with board, from the point downwards, 
 one-third of its height, the rest with cloth as usual. The 
 angles mentioned in the preceding article are found to be the 
 best for the enlarged sails also ; for in practice it is found, 
 that the sails had better have too little than too much wind. 
 
 Many persons have imagined that the more sail the greater 
 the advantage, and have therefore proposed to fill up the 
 whole area, and by making each sail a sector of an ellipsis. 
 
AND MACHTN’TST. 
 
 127 
 
 according to M. Parent, to Intercept the whole cylinder of 
 wind, and thereby to produce the greatest effect possible : 
 but from our author’s experiments it appears, that when the 
 surface of all the sails together exceeded seven-eighths of 
 the circular area containing them, the effect was rather 
 diminished than augmented; and consequently, he concludes, 
 that when the whole cylinder of wind is intercepted, it does 
 not then produce the greatest effect for want of proper 
 interstices to escape. 
 
 “ It is certainly desirable,’^ says Mr. Smeaton, that the 
 sails of windmills should be as short as possible, but at the 
 same time it is equally desirable the quantity of cloth should 
 be the least that may be, to avoid damage by sudden squalls 
 of wind. The best structure, therefore, for large mills, is 
 that where the quantity of cloth is the greatest in a given 
 circle that can be : on this condition, that the effect holds 
 out in proportion to the quantity of cloth; for otherwise the 
 effect can be augmented in a given degree by a lesser 
 increase of cloth upon a larger radius, than would be 
 required if the cloth were increased upon the same radius.” 
 
 The ratios between the velocities of windmill sails unloaded, 
 and when loaded to their maximum, turned out different in 
 different experiments, but the most general ratio of the whole 
 w’as as 3 to 2. In general, however, it appeared, w^here the 
 power was greater, whether by an enlargement of surface, or 
 a greater velocity of the wind, that the second term of the 
 ratio was less. 
 
 The ratio between the greatest load that the sails wdll bear 
 without stopping, or what is nearly the same thing, between 
 the least load that will stop the sails, and the load at the 
 maximum, were confined between that of 10 to 8, and of 10 
 to 9; and at a medium about 10 to 8.3, or of 6 to 5; though 
 it appeared on the whole, that where the angle of the sails or 
 quantity of cloth was greatest, the second term of the ratio 
 was less. 
 
 The following maxims have been deduced by Mr. Smeaton 
 from his experiments : 
 
 Maxim 1. The velocity of the windmill sails, whether unloaded or loaded, 
 so as to produce a maximum, is nearly as the velocity of the wind, their 
 shape and motion being the same, 
 
 Maxim 2. The load at the maximum is nearly, but somewhat less than, 
 as the square of the velocity of the wind, the shape and position of the 
 sails being the same. 
 
 Maxim 3. The effects of the same sails at a ma3.imum are iiea.Tly, but 
 somewhat less than, as the cubes of the velocity of the wind. 
 
 Maxim 4. The load of the same sails at the maximum is nearly as the 
 squares, and their effects as the cubes of their number of turns in a given time. 
 
THE OPERATIVE MECHANIC 
 
 i2B 
 
 Maxim 5. When the sails are loaded so as to produce a maximum at a I 
 given velocity, and the velocity of the wind increases the load containing j| 
 the same: first, the increase of effect, when the increase of the velocity of * 
 the wind is smaller, will be nearly as the squares of those velocities ; 
 secondly, when the velocity of the wind is double, the effects will be 
 nearly as 10 to 27^; but thirdly, when the velocities compared are more 
 than double of that where the given load produces a maximum, the effects 
 increase nearly in a simple ratio of the velocity of the wind. 
 
 Maxim 6. If sails are of a similar figure and position, the number of 
 turns in a given time will be reciprocally as the radius or length of the sail. 
 
 Maxim 7. The load at a maximum that sails of a similar figure and ■ 
 position will overcome, at a given distance from the centre of motion, will 
 be as the cube of the radius. 
 
 Maxim 8. The effect of sails of similar figure and position are as the 
 square of the radius. 
 
 Maxim 9. The velocity of the extremity of Dutch sails, as well as of the 
 enlarged sails, in all their usual positions when unloaded, or even loaded to a 
 maximum, are considerably quicker than the velocity of the wind. 
 
 Mr. Ferguson remarks, that it is almost incredible to 
 think with what velocity the tips of the sails move when 
 acted upon by a moderate wind. He several times counted 
 the number of revolutions made by the sails in 10 or 15 
 minutes ; and, from the length of the arms from tip to tip, 
 has computed, that if an hoop of the same size were to run 
 upon plain ground with equal velocity, it would go upwards 
 of 30 miles in an hour. 
 
 RULES FOR MODELLING THE SAILS OF WINDMILLS. 
 
 Fig. 127 is a fi'ont view of one of the four sails of a windmill. 
 The letters of reference will serve to explain the terms made 
 use of in the following description : 
 
 1. The length of the arm, or whip A A, reckoned from the centre of the 
 great shaft B to the outermost bar 19, governs all the rest. 
 
 2. The breadth of the face of the whip A, next the centre, is one-thirtieth 
 of the length of the whip, its thickness at the same end is three-fourths of 
 the breadth, and the back-side is made parallel to the face for half the 
 length of the whip, or to the tenth bar ; the small end of the whip is square, 
 and at its end is one-sixtieth of the length of the whip, or half the breadth 
 at the great- end. 
 
 3. From the centre of the shaft B to the nearest bar 1 of the lattice, is 
 one-seventh of the whip ; the remaining space of six-sevenths of the whip 
 is equally divided into 19 spaces, so as to make 19 bars ; one-ninth of one 
 of these spaces is equal to the mortises for the bars, the tenons of which 
 are made square where they enter and go through the whip, and conse- 
 quently the mortises must be square also. 
 
 4. To prepare the whip for mortising, strike a gage-score at about three- 
 fourths of an inch from the face on each side, and the gage-score, on the 
 leading side 4, 5, will give the face of all the bars on that side ; but on 
 the other side, the faces of all the bars will fall deeper than the gage-score, 
 according to a certain rule. To find the space to be set off for this purpose 
 for each bar, construct a scale in the following manner; 
 
 5. Extend the compasses to any distance at pleasure, so that six times 
 
AND MACHINIST. 
 
 129 
 
 that extent may be greater than the breadth of the whip at the seventh bar ; 
 set those six spaces off upon a straight line for a base, at the end of which 
 raise a perpendicular ; set off three spaces upon the perpendicular, and divide 
 the two spaces that are farthest from the base line into six equal parts each, 
 so that this quantity of two spaces may be equally divided into 12 spaces, 
 marked out by 1 3 points ; from each of these points draw a line to the 
 opposite end of the base, as so many rays to a centre, and the scale is finished. 
 
 6. To apply this scale to any given case, set off the breadth of the whip 
 at the last bar, (that is, the bar at the extremity of the sail,) from the 
 centre of the scale along the base towards the perpendicular; and at this 
 point raise a perpendicular to cut the ray nearest to the base ; also set off 
 the breadth of the whip at the seventh bar in the same manner, and at this 
 point erect another perpendicular to cut the thirteenth radius. From the 
 intersection of the perpendicular (drawn upon the breadth of the last bar) 
 with the first of the thirteen radii, to the intersection of the other perpendi- 
 cular with the thirteenth radius, draw an oblique line cutting all the rest, 
 and the distances of each of these last-mentioned points of intersection from 
 the base line is the space which the face of each bar is distant from the gage- 
 line on the driving side. 
 
 7. These distances give a difference set off for each bar till the seventh, 
 which same must be set off for all the rest to the first. 
 
 8. These mortises must be square to the leading side of the whip. 
 
 9. When the mortises are cut, let the face of the whip be sloped off so as 
 to agree with the face of the bars in every part. 
 
 10. Two-fifths of the whip are the length of the last or longest bar. 
 
 11. Five-eighths of the longest bar must be on the driving side of the 
 whip, and three-eighths on the leading side, each being reckoned from tlie 
 middle of the whip. 
 
 12. The proportion of the mortises already given determines the size of 
 the bars at the mortises, but their thickness must be diminished each way, 
 so as to be only one-half at the ends ; but the face must be kept of equal 
 breadth all the way. 
 
 13. The leading side goes no farther than the fourth bar, and there only 
 projects one-third of the projection of the last bar. 
 
 14. All the bars on the driving side are made hollowing in the arch of a 
 circle, which begins to spring one-third of the length of the bars on the 
 driving side from the whip ; and the sweep is such, that if a straight line be 
 applied to the face of the bar from the wmip to the end, the face of the bar 
 should leave the straight line about the breadth of the bar. 
 
 15. There ought to be three uplongs, as 3,2, 10, to the driving, and 
 
 two to the leading side, as 5, 4, to strengthen the lattice. Dr. Rees's Cyclopedia. 
 
 Mr. Richard Hall Gower, a gentleman in the sea-service of 
 the East India Company, has made some judicious experiments 
 with a view of determining the proper angles of weather which 
 ought to be given to the vanes of a vertical windmill : his 
 general conclusion is, that each vane should be a spiral, gene- 
 rated by the circular motion of a radius, and of a line moving 
 at right angles to the plane of a circular motion. Tlie con- 
 struction he deduces from his inquiries is simple, being this : 
 The length, breadth, and angle of weather at the extremity 
 of a vane being given ; to determine the angles of weather at 
 different distances from the centre, 
 
 K 
 
130 THE OPERATIVE MECHANIC 
 
 Let A B, fig. 129, be the length of the Tane; BC its breadth; and 
 BCD the angle of the weather at the extremity of the vane, equal to 
 20 degrees. With the length of the vane A B, and breadth B C, construct 
 t }'*3 isosceles triangle ABC: from the point 13 draw B D perpendicular to 
 C B, then B D is the proper depth of the vane. 
 
 Divide the line A B into any number of parts, (five for instance,) at those 
 divisions draw the lines 1 E, 2 F, 3 G, and 4 H, parallel to the line B C ; 
 also, from the points of division 1,2, 3, and 4, draw the lines 1 I, 2 K, 3 L, 
 and 4 M, perpendicular to 1 E, 2 F, 3 G, &c. all of them equal in length 
 to B D. Join E I, F K, G L, and HM; then the angles l EI, 2FK, 
 3 G L, and H M, are the angles of weather at those divisions of the vane ; 
 and if the triangles be conceived to stand perpendicular to the plane of the 
 paper, the angles I, K, L, M, and D, becoming the vertical angles, the 
 hypothenuse of these triangles Will, as before suggested, give a perfect idea 
 of the weathering of the vane as it recedes from the centre. 
 
 METHOD OF CLOTHING AND UNCLOTHING THE SAILS WHILE IN 
 
 MOTION. 
 
 Ma. John Bywater, of Nottingham, took out a patent in 
 1804, for a method of clothing and unclothing the sails of 
 windmills while in motion, by which the mill may be clothed 
 cither in whole or in part, in an easy and expeditious manner, 
 by a few revolutions of the sails, whether they be going fast 
 or slow, leaving the surface smooth, even, and regular in 
 ])readth from top to bottom; and in like manner the cloth, 
 or any part of it, may be rolled or folded up to the whip at 
 pleasure, by simple and durable machinery. 
 
 Fig. 130, Nos. 1, 2, 3, are front views of the sails as unclothed, half- 
 clothed, and clothed. 
 
 Fig. 131, a ring of iron, or other material, about 4 inches wide, and | of 
 an inch thick, whose diameter must be sufficient to embrace the shaft-head, 
 to which it must be well secured by the stays a a. 
 
 Fig. 132, a bevelled wheel, without arras, made of iron, stayed on the 
 edge of the ring so as to turn easily. ^ 
 
 Fig. 133, a spur wheel of iron, without arms, made to turn easily on four 
 pins fixed into four ears bbbb, 'm the back of the ring ; which pins ara 
 turned up at their ends to keep it steady. 
 
 Fig. 134 is one of the four spindles of iron, or other material, with a 
 spur nut a, and a bevelled nut b ; this spindle passes through fig. 131 at 
 c a cc, and the nut a works into the spur-wheel as seen in fig. 135, aaaa. 
 The four bevelled nuts (fig. 134) work into the bevelled wheels at the end 
 of four cylinders iiii fig. 130, Nos. 1, 2, 3, and so turn them ; and two 
 of these spindles must be shorter than the others when the stocks are net 
 flush. These cylinders are made of wood of about 3 inches diameter, 
 and are to be placed at the outside of the leading edge of each sail, round 
 which the cloth is rolled (one edge being fastened on for that purpose) 
 when the sail is unclothed. A gudgeon from the end of each cylinder 
 runs into an iron fastened to the shaft-head, and is kept in its place by a 
 nut screwed to its end. The other end has a gudgeon b, which turns in 
 the eye of the cross iron h, at the points of the whips ; ffff four cylinders, 
 similar to i i i i, placed on the inside the whips ; one behind each sail to 
 clothe the sails, by means of ropes o o oo, &c. fastened to them-and the edge 
 of the cloth. At the end of each of these four cylinders a nut or wheel is 
 
From 130 to 139 
 
 II.J3. 
 
 134 
 
 ><u>rldey Sti\md 
 
AND MACHINIST. 
 
 131 
 
 fixed, eeee^ to work into the bevelled wheel; fig. 133, whose teeth 
 decline from the centre in proportion as these work from it, which 
 declination must be reversed when the sails turn in the contrary way, and 
 gudgeons to run into irons either projecting from the ring or fastened to the 
 shaft-head like the other cylinders. The gudgeons g keep these cylinders 
 steady in the cross iron h at the point of the whips, and stays of any shape 
 or number will keep them from springing. 
 
 Now, suppose the mill fully clothed, as at 3, all the parts of the 
 machinery revolve with it undisturbed until a lever, fig. 136, which is 
 fastened to the braces or fencing, by the centre pin a, fig. 1 37, on which it 
 turns, and whose end h is weighted to hang down towards the breast of 
 the mill, is brought into an horizontal direction by pulling a string attached 
 to the end a within-side the mill, which end b stops the stud h, projecting 
 from the inner surface or back-front of the spur-wheel, fig. 135; conse- 
 quently the four spur-ntlts a, at the end of the spindle, fig. 134, and seen at 
 aaaa, fig. 135, roll round the spur-wheel, and the bevelled nuts b at the 
 other end of the spindle work into the bevelled wheels of the outside 
 cylinders at 1, 2, 3, in a straight direction behind them, and so 
 
 turning the cylinders roll the cloth on them till it is rolled up to the whip. 
 The lever is then driven sideways (its spring c returning it again) from 
 the stud in the back face of the spur-wheel by the following contrivance : 
 
 A screw, 5, fig. 138, is cut on the gudgeon of any one of the cylinders 
 behind the sail, and a piece of iron, c, is tapped to fit it. The end of this 
 iron runs into a slot in the iron d, made fast to the shaft-head, to prevent 
 the iron c from turning with the cylinder, but allows it to slide up and 
 down so as to press on that on the iron a, which has the eye in it, and 
 raises the end a just high enough to drive the lever aside when the cloth 
 is all rolled up, the thread of the screw adjusting it to what number of 
 revolutions you choose to employ for that purpose. The point-end of the 
 iron a, is that part of it which pushes aside and passes the lever, fig. 136, 
 and moves on its centre c, and must be carried under the spur-wheel so as 
 to act behind it for that purpose. By letting go the string the miller may 
 at any time leave the cloth on the sail where he chooses, likewise the sails 
 may be clothed, or any part thereof, by a lever, similar to a, stopping the 
 stud a, on the edge of the bevelled wheel, fig. 132, and driven off in a 
 manner similar to the spur-wheel. 
 
 Fig. 139 is a stay of wood, fixed to the stock or whip at n n n n, 1, 2, 3, 
 to prevent the cylinders from springing too much. In the inside there is 
 left room enough for the cloth to be rolled upon the cylinder through its 
 lips in the eye of this stay. In order to keep the strings, which go over the 
 edge of the shrouds oo o o, &c. tight in all weathers, a cord, passing over 
 a spring of any sort or shape, placed under the sail, is fastened to and 
 wound about the upper ends of the cylinders, in a direction contrary to the 
 strings and cloth. To prevent the strings frorn being driven downwards by 
 the centrifugal force, a ring or two are left on to run along the rods in the 
 old manner asp. Nos. 2, 3. 
 
 The width of the cloth, diameter of the cylinders, and 
 number of revolutions you choose to employ to roll up your 
 cloth, must determine the size of the wheels* In order to 
 fold the cloth instead of rolling it, one end of it must be 
 fastened to the whip and lines passed across the outside of it 
 through loops fastened to its edge, and consequently over 
 the edge of the shrouds, and connected with the cylinder or 
 
132 
 
 THE OPERATIVE MECHANIC 
 
 roller, of any shape, placed under the sail, or elsewhere, the 
 other ends of the lines must be connected with the said 
 cylinder or roller; and when the cloth is drawn up in folds 
 towards the whip, so much of these lines will be rolled on 
 the cylinder one way, and off from it the other, as will be 
 sufficient to let out the cloth again when the same cylinder, 
 turning the contrary w'ay, draws the cloth on the sail; By 
 this mode the patentee gets rid of fom* cylinders, with their 
 appendages, the work being in other respects the same as in 
 rolling the cloths ; but since folding gives a surface much 
 inferior in many respects to rolling, and induces incon- 
 veniences and accidents from which the rolled surface is free, 
 he advises the rolling, rather than for a small saving to endure 
 the inconveniences of folding. 
 
 If a sudden gust of wind should arise in the absence of the 
 miller, so as to drive the mill faster than a given velocity, a 
 pair of centrifugal balls, like the governor of a steam engine, 
 may be so placed as to adjust the lever so that it may 
 immediately unclothe itself. 
 
 Baines’s vertical windmill sails. 
 
 Mr. Robert Raines Baines, of Myton, Kingston upon 
 Hull, secured to himself in June 1815, by patent, an improve- 
 ment in the construction of vertical windmill sails. 
 
 Fig. 140 represents six sails; the stocks or arms marked A are the same 
 as used for common vertical windmills ; the sails marked B are made of 
 canvass, and fastened to the front sides of the said stocks or arms along the 
 edges marked a, a, and to the rods or bars marked D, at or near the point 
 marked h, and are also extended by the rods or bars marked E, which are 
 inserted into or fixed to the backs thereof, and by rods or bars marked m, 
 which are inserted into or fastened to the edges of thje said sails; each sail 
 is also connected by a bar or rod marked F, as hereinafter described, 
 with the next following sail. Tlie shafts or rods marked C are fastened to 
 the stocks or arms marked A, at or near d, d, by loops or otherwise, so as 
 to allow them to move as hinges do. Tlie bars or rods marked D are each of 
 them connected with the shafts or rods marked C by a joint, which will 
 allow the said bars or rods marked D to move from the wind independent 
 of the shafts or rods marked C, in case it should blow against the back sides 
 of the said sails, but will not allow the said bars or rods marked D to move 
 from the wind independent of the said shafts or rods marked C, when the 
 wind blows against the front sides of the said sails. The bars or rods 
 marked F connect the corners marked e of each sail with the corner of the 
 next following sail at or near the point marked b, leading behind such 
 following sail, and which bars or rods are fastened by hooks, or other proper 
 means, at or near their points, bent to such an angle that if the wind 
 should blow against the back sides of the said sails and force them forward, 
 the said bars or rods will be unhooked and set at liberty A rim or circle 
 marked G is fixed by screws or otherwise upon the said stocks or arms 
 marked A, for the purpose of supporting the fulcra or props marked H. 
 At I is represented the head or end of a rod or bar wliich passes through 
 
AND MACHINIST. 
 
 133 
 
 the centre of the axletree of the mill, and to which weight may be applied, 
 in the manner well known to mill-wrighls, to regulate the said sails 
 towards or from the wind. The bars or cranks marked K are fixed to the 
 shafts or rods marked C, at such an angle, and in such a manner as will, 
 when and as they are acted upon by the levers or bars marked L, either 
 suffer the said bars or rods marked D and the sails to recede from the wind 
 until the said sails present only their edges to it, or will force the said 
 bars or rods marked D towards the wind, until they present to it their 
 breadth. The levers or bars marked L are connected at one of their ends 
 with the head of the aforesaid rod marked and at the other ends with the 
 bars or cranks marked K, and form levers resting or acting upon the fulcra 
 or props marked H, and are governed or regulated in their action by the 
 said rod, the head of which is shown at I. The said rods, bars, cranks, 
 loops, and rim, may be made of iron, or other suitable material or materials, 
 and connected at their proper places by joints or otherwise, (so as to fix 
 them or allow their action,) by modes well known to raill-wrights. 
 
 cubitt’s method op equalizing the motion of the sails 
 
 OF WINDMILLS. 
 
 Mr. William Cubitt^ of North Walsham, Norfolk, en- 
 gineer, took out a patent for this invention in May 1807, 
 which the specification thus describes : 
 
 My invention consists in applying to windmills an appa- 
 ratus or contrivance which shall cause the vanes, constructed 
 or formed in a new and peculiar manner, to regulate them- 
 selves, so as to preserve an uniform velocity under those 
 circumstances in which the wind would otherwise irregularly 
 impel them, as is the case with the sails or vanes of mills of 
 the present construction. I accomplish this object by forming 
 the vanes (for the sake of lightness) with fewer cross bars or 
 shrouds than in the common method, and filling up the 
 remaining open space with small flat surfaces, formed either of 
 boards or sheet iron painted, or any other fit substance, (though 
 I prefer and recommend them to be made of a framing of 
 wood, covered over with canvass.) I hang or suspend the 
 same on their ends by gudgeons, pivots, centres, or any other 
 convenient method, so as to open and shut like valves, (for 
 w^hich reason I shall hereafter so call them,) preferring 
 always to have the centre of motion as near the upper longi- 
 tudinal edge of the valve as possible, as shown in the drawing, 
 h b, fig. 141, which exhibits a valve detached. I apply these 
 valves to vanes of the present construction, by suspending 
 them to the cross bars or shrouds of the vane by their longi- 
 tudinal edges, fastened thereto by joints or otherwise, as may 
 be preferred. These vanes, constructed of valves as above 
 .described, and which are represented in the drawing, fig. 142, 
 present a greater or less surface to the wind, according as it 
 acts with more or less force on them ; and if the wiiid be very 
 
134 
 
 THE OPERATIVE MECHANIC 
 
 strong or high, the valves, by its impulse, V’ould turn their 
 edges to it, and their surfaces parallel to the direction of the 
 wind^ the vanes would consequently remain stationary, or 
 at least have but little motion; but to obviate this circum- 
 stance taking place, I apply an apparatus which shall cause 
 the valves always to present their flat surfaces to the wind, 
 or such portion of their surfaces as may be desirable. The 
 apparatus which I have usually applied is exhibited in the 
 drawings, figs. 143 and 144, which last figure shows two 
 modes of performing this object; though it must be evident 
 that various other means may be applied to produce the same 
 effect on the valves, and I therefore do not mean to confine 
 myself to those precise modes of effecting it, but consider it 
 unnecessary here to detail others, as the examples exhibited 
 in the drawings fully ascertain the sort of apparatus requisite. 
 
 Fig. 142 represents a set of vanes, in which A A show the valves turned 
 to the wind, and their surfaces all exposed at right angles with the direction 
 of the wind ; B B exhibit the vanes as close reefed, or the valves with their 
 edges to the wind, so that it can have no effect upon them except on their 
 edges, which must be trifling. In the drawing, the vanes are exhibited as 
 having the whip down the middle, with valves on both sides ; but it is 
 evident that the vanes may be constructed with the whip placed in the 
 usual way, and have valves on one side only, which is the method I usually 
 adopt in applying them to vanes of the present form. 
 
 “Fig. 143 represents a side view of the apparatus for regulating the 
 valves; and fig. 144 is a section of the same, exhibiting two methods 
 of performing this operation. A represents the shaft, which is bored 
 through its centre to admit an iron rod B to pass freely through it ; one 
 end of this rod is made to turn in a box C, which is fastened to a toothed 
 rack D, wh 9 se teeth take into those of a pinion E, upon the axis of which is 
 a sheave F, with a groove on its circumference to receive a rope G, to 
 which is hung a weight, shown at H, fig. 143, and which must be sufficient 
 to regulate the force of the wind upon the valves, though no precise 
 quantity of weight can be herein specified, as the same must be adjusted 
 by experiment, or by the quantity of work to be performed by the mill. 
 On the top of the rack D is a roller I, which serves to keep the rack and 
 pinion in the proper depth of geer. The end of the rod B, which turns in 
 the box C, has a knob or onion on it, by which it can be moved endwise 
 while it is turning in the box C. In the other end of the rod is fixed a boss 
 or plate of iron K, with a gudgeon projecting from each side, on which are 
 the bridles or leaders LL, which permit the levers M M to describe a 
 curve with their ends while the iron rod B moves in a straight line. N N 
 are two studs or props fixed to the stock O of the sail ; on the ends of 
 which props the levers M M move, and communicate their motion to the 
 racks P P, the teeth of which take into the pinions Q Q, on the axis of 
 which, (according to one method herein exhibited, fig. 145,) is fixed a 
 strong iron stud R, which is attached to a rack or slider S. Iron studs or 
 levers are fixed at one end in this slider S by a pin or gudgeon, and at the 
 other made fast to the valves a, which move on gudgeons as before 
 described. 
 
 The other method of regulating the valves is shown at 
 
AND MACHINIST. 
 
 135 
 
 fig. 14G, where, instead of the studs or levers, the valves may 
 be moved by having pinions fixed to them, and working with 
 teeth in a rack or slider, as at T. V V are rollers to keep 
 the racks P in their geer. I’he operation of this apparatus 
 will be clearly comprehended by imagining that if the hook 
 4, on the rope G, be pulled down to 5, the sheave F with the 
 pinion £ will turn at the same time, putting in motion the rack 
 D with the rod B, which will bring the levers M M into the 
 position represented by the dotted lines : the racks P will 
 have turned the pinions Q till the sliders S and T, with the 
 studs or levers, or racks, (according to whichever method 
 may be used,) bring the valves into the position of the 
 dotted lines, in which position they are represented as having 
 all their surfaces to the wind ; therefore, if a sufficient weight 
 be hung to the hook 4, the weight will descend to 5, and 
 keep the valves in the situation of the dotted lines ; and 
 supposing the wind to blow upon them with too much force 
 ill this state, they will turn on their gudgeons, and raise the 
 weights, so that the superfluous wind will pass through or 
 between them, without exerting an irregular force upon the 
 vanes, so as to produce an unequal velocity.'" 
 
 MILL WITH EIGHT QUADRANGULAR SAILS. 
 
 This mill, which is the invention of Mr. James Verrier, is 
 represented in fig. 14J. 
 
 AAA are the three p.rincipal posts, 27 feet inches long, 22 inches 
 broad at their lower extremities, 18 inches at their upper, and 17 inches 
 thick. The column B is 12 feet 2^ inches long, 19 inches in diameter 
 at its lower extremity, and 16 inches at its upper: it is fixed in the 
 centre of the mill, passes through the first floor E, having its upper 
 extremity secured by the bars G G. E E E are the girders of the first 
 floor, one of which only is seen, being eight feet three inches long, 1 1 inches 
 broad, and nine thick ; they are mortised into the posts AAA and the column 
 B, and are about eight feet three inches distance from the ground floor. D D,D 
 are three posts, six feet four inches long, nine inches broad, and six inches 
 thick : they are mortised into the girders E F of the first and second floor, 
 at the distance of two feet four inches from the posts A, &c. F F F are the 
 girders of the second floor, six feet long, 1 1 inches broad, and nine thick : 
 they are mortised into the posts A, &c., and rest upon the upper extremities 
 of the posts D, &c. Tire three bars GGG are 3 feet 1§ inches long, 
 seven inches broad, and three thick : they are mortised into the posts D and 
 the upper end of the column B, four feet three inches above the floor. P 
 is one of the beams which support the extremities of the bray-trees or 
 brayers ; its length is two feet four inches, its breadth eight inches, and its 
 thickness six inches. I is one of the bray-trees into which the extremity of 
 one of the bridge-trees K is mortised. Each bray-tree is 4 feet 9§ inches 
 long, 9i inches broad, and seven thick, and each bridge-tree is four feet 
 six inches long, nine inches broad, and seven thick; being furnished 
 with a piece of brass on its upper surface to receive the under pivot of the 
 mill-stones. LL are two iron screw-bolts, which raise or depress the 
 
136 
 
 THE OPBRATIVB MECHANIC 
 
 extremities of the bray-trees. M M M are the three mill-stones, and 
 N N N the iron spindles or arbors on “which the turning mill-stones are 
 fixed. D is one of three wheels or trundles which are fixed on the upper 
 ends of the spindles NNN: they are 16 inches in diameter, and each is 
 furnished with 14 staves; /is one of the carriage-rails on which the upper 
 
 f )ivot of the spindle turns, and is four feet two inches long, seven inches 
 )road, and four thick. It turns on an iron bolt at one end, and the other 
 end slides in a bracket fixed to one of the joints, and forms a mortise in 
 which a wedge is driven to set the rail and trundle in or out of work : 
 t is the horizontal spur-wheel that impels the trundles ; it is five feet six 
 inches in diameter, is fixed to the perpendicular shaft T, and is furnished 
 with 42 teeth. The perpendicular shaft T is nine feet one inch long, and 
 14 inches in diameter, having an iron spindle at each of its extremities; the 
 under spindle turns in a brass block fixed into the higher end of the 
 column B ; and the upper spindle moves in a brass plate inserted into the 
 lower surface of the carriage-rail C. The spur-wheel r is fixed on the 
 upper end of the shaft T, and is turned by the crown-wheel v on the 
 wind shaft c ; it is three feet two inches in diameter, and is furnished with 
 15 cogs. The carriage-rail C, which is fixed on the sliding kerb Z, is 
 1 7 feet 2 inches long, one foot broad, and nine inches thick. Y Y Q is the 
 fixed kerb, 17 feet 3 inches diameter, 14 inches broad, and 10 thick, and 
 is mortised into the posts A A A, and fastened with screw-bolts. The 
 sliding kerb Z is of the same diameter and breadth as the fixed kerb, but its 
 thickness is only 7f inches; it revolves on 12 friction rollers fixed on the 
 upper surface of the kerb Y Y Q, and has four iron half-staples, Y, Y, &c., 
 fastened on its outer edge, whose perpendicular arms are 10 inches long, 
 two inches broad, and one inch thick, and embrace the outer edge of the 
 fixed kerb, to prevent the sliding one from being blown off. Tlie capsills 
 XV are 13 feet 9 inches long, 14 inches broad, and 1 foot thick : they 
 are fixed at each end with strong iron screw bolts to the sliding kerb, 
 and to the carriage-rail C. On the right hand of tv is seen the extremity of 
 a cross-rail, which is fixed into the capsills XV by strong iron bolts; <? is a 
 bracket 5 feet long, 16 inches broad, and 10 inches thick; it is bushed with 
 a strong brass collar, in which the inferior spindle of the windshaft turns, 
 and is fixed to the cross-rail tv ; b is another bracket, seven feet long, four 
 feet broad, and 10 inches thick; it is fixed into the fore ends of the capsills, 
 and in order to embrace the collar of the windshaft, it is divided into two 
 parts, which are fixed together with screw-bolts. The windshaft c is 15 feet 
 long, two feet in diameter at the fore end, and 18 inches at the other; its 
 pivot at the back end is six inches diameter ; and the shaft is perforated, 
 to admit an iron rod to pass easily through it. The vertical crown-wheel v 
 is six feet in diameter, and is furnished with 54 cogs, which drive the spur- 
 wheel r ; the bolster d, which is six feet three inches long, 13 inches broad, 
 and half a foot thick, is fastened into the cross-rail iv, directly under the 
 centre of the windshaft, having a brass pulley fixed at its fore end. On the 
 upper surface of this bolster is a groove in which the sliding bolt R moves, ! 
 having a brass stud at its fore end. This sliding bolt is not distinctly seen } i 
 in the figure, but the round top of the brass stud is visible below the i ' 
 letter h ; the iron rod that passes through the windshaft bears against this 
 brass stud. The sliding bolt is four feet nine inches long, nine inches j | 
 broad, and one-third of a foot thick. At its fore end is fixed a line which L.| 
 passes over the brass pulley in the bolster, and appears at a with a weight 
 attached to its extremity, sufficient to make the saib face the wind that is 
 strong enough for the number of stones employed ; and when the pressure 
 of the wind is more than sufficient, the sails turn on an edge and press back 
 ibe sliding bolt, which prevents them from moving with too great velocity • 
 
iiiiiiiiniitiii 
 
 lilies 
 
 from 147 to 15L 
 
 PLis. 
 
AND MACHINIST. 
 
 137 
 
 and as soon as the wind abates, the sails, by the weight «, are pressed up 
 to the wind till its force is sufficient to give the mill a proper degree of 
 velocity. By this apparatus the wind is regulated and justly proportioned 
 to the resistance, or work to be performed ; an uniformity of motion is also 
 obtained, and the mill is less liable to be destroyed by the rapidity of its 
 motion. 
 
 That the reader may understand how these effects are produced, we have 
 represented in fig. 148, the iron rod, and the arms which bear against the 
 vanes; a A is the iron rod which passes through the windshaft c, in fig. 147 ; 
 h ii the extremity which moves in the brass stud that is fixed upon the 
 sliding bolt; a i, are the cross-arms at right angles to ah, whose 
 
 extremities i, i, similarly marked in fig. 147, bear upon the edges of the 
 vanes. The arms a i are 6§ feet long, reckoning from the centre a, one foot 
 broad at the centre, and five inches thick ; the arms 7i, n, &c., that carry the 
 vanes or sails, are 18§ feet long, their greatest breadth is one foot, and their 
 thickness nine inches, gradually diminishing to their extremities, where they 
 are three inches in diameter The four cardinal sails, m, m, m, m, are each 
 13 feet long, eight feet broad at their outer end, and three feet at their lower 
 extiemities; p, p, &c., are the four assistant sails which have the same 
 dimensions as the cardinal ones, to which they are joined by the line S S S S. 
 Tlie angle of the sail’s inclination when first opposed to the wind js 
 45 degrees, and regularly the same from end to end. 
 
 It is evident from the preceding description of this machine, that the 
 windshaft c moves along with the sails ; the vertical crown-wheel v impels 
 the spur-wheel r, fixed upon the axis T, which carries also the spur-wheel 
 t. This wheel drives the three trundles H, one of which only is seen in 
 the figure, which being fixed upon the spindles N, &c. communicate motion 
 to the turning mill-stones. 
 
 That the wind may act with the greatest efficacy upon the 
 sails, the windshaft or principal axis must always have the 
 same direction as the wind. But as this direction is per- 
 petually changing, some apparatus is necessary for bringing 
 the windshaft and sails into their proper position. As both 
 the common methods of adjusting the windshaft require 
 human assistance, it would be very desirable that the same 
 effect should be produced solely by the action of the wind. 
 This may be done by fixing a large wooden vane or weather- 
 cock at the extremity of a long horizontal arm which lies in 
 the same vertical plane with the windshaft. By this means, 
 when the surface of the vane and its distance from the centre 
 of motion are sufficiently great, a very gentle breeze will 
 exert a sufficient force upon the vane to turn the machinery, 
 and will always bring the sails and windshaft to their proper 
 position. This weathercock, it is evident, may be applied 
 either to machines which have a movable roof, or to those 
 which revolve upon a vertical arbor. Prior to the French 
 revolution, windmills were more numerous in Holland and 
 the Netherlands than in any other part of the world, and 
 there they seem to have been brought to a very high state of 
 perfection. This is evident not only from the experiments 
 
138 
 
 the operative mechanic 
 
 of Mr. Smeaton, from which it appears that sails weathered 
 in the Dutch manner produced nearly a maximum effect, but 
 also from the observations of the celebrated Coulomb. This 
 philosopher examined above 50 windmills in the neighbour- 
 hood of Lisle, and found that each of them performed nearly 
 the same quantity of work when the wind moved with the 
 velocity of 18 or 20 feet per second, though there were some 
 trifling differences in the inclination of their windshafts, and 
 in the disposition of their sails. From this fact, Coulomb 
 justly concluded that the parts of the machine must have 
 been so disposed as to produce nearly a maximum effect. 
 
 In the windmills on which Coulomb’s experiments were 
 made, the distance from the extremity of each sail to the 
 centre of the windshaft or principal axis was 33 feet. The 
 sails were rectangular, and their width was a little more than 
 six feet, five of which were formed with cloth stretched upon 
 a frame, and the remaining foot consisted of a very light board. 
 The line which joined the board and the cloth formed, on the 
 side which faced the wind, an angle sensibly concave at the 
 commencement of the sail, which diminished gradually till it 
 vanished at its extremity. Though the surface of the cloth was 
 curved, it may be regarded as composed of right lines perpendi- 
 cular to the arm or whip which carries the frame, the extre- 
 mities of these lines corresponding with the concave angle 
 formed by the junction of the cloth and the board. Upon this 
 supposition, these right lines at the commencement of the sail, 
 which was distant about six feet from the centre of the 
 windshaft, formed an angle of 60 degrees with the axis or 
 windshaft, and the lines at the extremity of the wing formed 
 an angle increasing from 78 to 84 degrees, according as the 
 inclination of the axis of rotation to the horizon increased 
 from 8 to 15 degrees ; or in the mill-wright’s terms, the 
 greatest angle of weather was 30 degrees, and the least 
 varied from 12 to 6 degrees, as the inclination of the windshaft 
 varied from 8 to 15 degrees. A pretty distinct idea of the 
 surface of windmill sails may be conveyed by conceiving a 
 number of triangles standing perpendicular to the horizon, 
 in which the angle contained between the hypothenuse and 
 the base is constantly diminishing ; the hypothenuse of each 
 triangle will then be in the superficies of the vane, and they 
 would form that superficies if their number were infinite. 
 
AND MACHINIST. 
 
 139 
 
 ON HORIZONTAL WINDMILLS. 
 
 A VARIETY of opinions have been entertained respecting 
 the relative advantages of horizontal and vertical windmills. 
 Mr. Smeaton gives a decided preference to the latter; but^ 
 when he asserts that horizontal wind mills have only one-eighth 
 or one-tenth of the power of vertical ones, he certainly forms 
 too low an estimate of their power. Mr. Beatson, on the 
 contrary, who has a patent for the construction of a new 
 horizontal windmill, seems to be prejudiced in their favour. 
 From an impartial investigation, it will probably appear, 
 that the truth lies between these tw'o opposite opinions ; but 
 before entering on this discussion, we must first consider the 
 nature and form of horizontal windmills ; which we shall do 
 in presenting the reader with a description of the horizontal 
 mill erected at Margate by Captain Hooper, 
 
 Fig. 149 is an upright section, and fig. 150 a plan of the building. 
 H H are the side walls of an octagonal building which contains the 
 machinery. These walls are surmounted by a strong timber framing 
 G G, of the same form as the building, and connected at top by 
 cross-framing to support the roof, and also the upper pivot of the main 
 vertical shaft A A, which has three sets of arms, B B, C C, D D, framed 
 upon it at that part which rises above the height of the walls. The arms 
 are strengthened and supported by diagonal braces, and their extremities 
 are bolted to octagonal wood frames, round which the vanes or floats E E 
 are fixed, as seen in outline in fig. 150, so as to form a large wheel, resem- 
 bling a water-wheel, which is less than the size of the house by about 
 18 inches all round This space is occupied by a number of vertical 
 boards or blinds F F, turning on pivots at top and bottom, and placed 
 obliquely, so as to overlap each other, and completely shut out the wind, and 
 stop the mill, by forming a close case surrounding the wheel ; but they can 
 be moved altogether upon their pivots to allow the wind to blow in the 
 direction of a tangent upon the vanes on one side of the wheel, at the time 
 the other side is completely shaded or defended by the boarding. The 
 position of the blinds is clearly shown at F F, fig. 150. At the lower end 
 of the vertical shaft A A, a large spur-wheel a a is fixed, which gives motion 
 to a pinion c, upon a small vertical axis d, whose upper pivot turns in a 
 bearing bolted to a girdei of the floor n. Above the pinion c, a spur- 
 wheel e is placed, to give motion to two small pinions /, on the upper ends 
 of the spindles of the mill-stone h. Another pinion is situate at the 
 opposite side of the great spur-wheel a a, to give motion to a third pair of 
 mill-stones, which are used when the wind is very strong; and then the 
 wheel turns so quick as not to need the extra wheel e to give the requisite 
 velocity to the stones. The weight of the main vertical shaft is borne by a 
 strong timber 6, having a brass box placed on it to receive the lower pivot of 
 the shaft. It is supported at its ends by cross-beams mortised into the upright 
 posts h b, as shown in the plan, fig. 150. A floor or roof 1 1 is thrown across 
 the top of the brick-building to protect the machinery from the weather, and 
 to prevent the rain blowing down the opening through which the shaft descends, 
 a broad circular hoop K is fixed to the floor, and is surrounded by another hoop 
 or case L, which is fixed to the arms D D of the wheel, lliis last is of such a 
 
140 
 
 THE OPERATIVE MECHAMC 
 
 size, as exactly to go over the hoop K, without touching it when the wheel 
 turns round. By this means, the rain is completely excluded Crom the 
 upper room M, which serves as a granary, being fitted up wuth the bins 
 m m, to contain the different sorts of grain which is raised up by the sack- 
 tackle. A w'heel i is fixed on the main shaft, having cogs projecting from 
 both sides. Those at the under side work into a pinion on the end of the 
 roller K, which is for the purpose of drawing up sacks. Another pinion is 
 situated above the w^heel i, which has a roller projecting out over the flap- 
 doors seen at p, in fig. 150, to land the sacks upon. The two pinions m m, 
 fig. 150, are turned by the great wheel a a, and are for giving motion to the 
 dressing and bolting machines, which are placed upon the floor N, but are 
 not shown in the drawing, being exactly similar to the dressing machines 
 used in all flour-mills. The cogs upon the great wheel a are not so broad 
 as the rim itself, leaving a plain rim about three inches broad. Tliis is 
 encompassed by a broad iron hoop, which is made fast at one end to the 
 upright post b ; the other being jointed to a strong lever ?», to the extreme 
 end of which a purchase o is attached, and the fall is made fast to iron pins 
 on the top of a frame fixed to the ground. TTiis apparatus answers the 
 purpose of the brake or gripe used in common windmills to stop their 
 motion. By pulling the fall of the purchase o, it causes the iron strap to 
 embrace the great wheel, and produces a resistance sufficient to stop the 
 w'heel. The mill can be regulated in its motion, or stopped entirely, by 
 opening or shutting the blinds F, w’hich surround the fan- wheel. They are 
 all anoved at once by a circular ring of wood situated just beneath the 
 lower ends of the blinds upon the floor 1 1, being connected with each blind 
 by a short iron link. Tlie ring is moved round by a rack and spindle which 
 descend into the mill-room below, for the convenience of the miller. 
 
 The mode of bringing the sails back against the wind, which Mr. Beatson 
 invented, is, perhaps, the simplest and best for that end. He makes each 
 sail A I, fig. 151, to consist of six or eight flaps or vanes, A P, 51, 5 1, c 2, 
 &c., moving upon hinges represented by the dark lines, AP, 51, c2, &c., 
 so that the low^er side 5 1 of the first flap wraps over the hinge or higher 
 side of the second flap, and so on. "When the wund, therefore, acts upon 
 the sail A I, each flap will press upon the hinge of the one immediately 
 below it, and the whole surface of the sail will be exposed to its action. 
 But when the sail A I returns against the wind, the flaps will revolve round 
 upon their hinges, and present only their edges to the wind, as is repre- 
 sented at E G, so that the resistance occasioned by the return of the sail 
 must be greatly diminished, and the motion will be continued by the great 
 superiority of force exerted upon the sails in the position A I. In com- 
 puting the force of the wund upon the sail A I, and the resistance opposed 
 to it by the edges of the flaps in E G, Mr. Beatson finds, that when the 
 pressure upon the former is 1872 pounds, the resistance opposed by the 
 latter is only about 36 pounds, or part of the whole force ; but he 
 neglects the action of the wind upon the arms, C A, &c., and the frames 
 which carry the sails, because they expose the same surface in the position 
 A I, as in the position E G. This omission, however, has a tendency to 
 mislead us in the present case, as we shall now see; for w'e ought to 
 compare the whole force exerted upon the arms, as well as the sail, with 
 the whole resistance which these arms and the edges of the flaps oppose to 
 the motion of the windmill. By inspecting the figure it will appear, that if 
 the force upon the edges of the flaps, which Mr. Beatson supposed to be 
 1 2 in number, amounts to 36 pounds, the force spent upon the bars C D, 
 E) G, G F, F E, &c., cannot be less than CO pounds. Now, since these 
 bars are acted upon with an eoual force, when the sails have the position 
 
AND MACHINIST. 
 
 141 
 
 A 1, 1872 + 60 = 1932 will be the force exerted upon the sail A I and its 
 appendages, while the opposite force upon the bars and edges of the flaps 
 when returning against the wind will be 36 + 60 = 96 pounds, which is 
 nearly ^ of 1932, instead of as computed by Mr. Beatson. Hence we 
 may see the advantages which will probably arise from using a screen for 
 the returning sail instead of movable flaps, as it will preserve not only the 
 sails, but the arms and the frame which supports it, from the action of the 
 wind.* 
 
 Mr. Brewster makes also the following remark on the 
 comparative power of horizontal and vertical windmills. It 
 has been already stated, that Mr. Smeaton rather unden-ated 
 the former while he maintained that they have only one- eighth 
 or one-tenth the power of the latter. He observes, that when 
 the vanes of a horizontal and a vertical mill are of the same 
 dimensions, the power of the latter is four times that of the 
 former ; because, in the first case, only one sail is acted upon 
 at once; while, in the second case, all the four receive the 
 impulse of the wind. This, however, is not strictly true, 
 since the vertical sails are all oblique to the direction of the 
 wind. Let us suppose that the area of each sail is 100 square 
 feet; then the power of the horizontal sail may be called 
 100 X sin.^ 70 ° (which is the common angle of inclination) 
 = 88 nearly ; but since there are four vertical sails, the 
 power of them all will be 4 X 88 = 362 : so that the power 
 of the horizontal sail is to that of the four vertical ones as 
 1 to 3.52, and not as 1 to 4, according to Mr. Smeaton. 
 But Mr. Smeaton also observes, that if we consider the 
 further disadvantages which arises from the difficulty of 
 getting the sails back against the wind, we need not wonder 
 if horizontal windmills have only about or tV of the com- 
 mon sort. We have already seen that the resistance occa- 
 sioned by the return of the sails amounts to ^ of the 
 whole force which they received; by subtracting ^ there- 
 fore, from we shall find that the power of horizontal 
 windmills is only or little more than one-fourth less 
 than that of vertical ones. This calculation proceeds upon a 
 supposition that the whole force exerted upon vertical sails 
 is employed in turning them round the axis of motion; 
 whereas a considerable part of tliis force is lost in pressing 
 the pivot of the axis or windshaft against its gudgeon. 
 Mr. Smeaton has overlooked this circumstance, otherwise he 
 could never have maintained that the power of four vertical 
 
 * The sails of horizontal windmills are sometimes fixed like float-hoards on 
 the circumference of a large drum or cylinder. These sails move upon hinges 
 so as to stand at right angles to the drum, when they are to receive the impulse 
 of the wind ; and when they return against it, they fold down upon Its circum- 
 ference. 
 
142 
 
 THE OPERATIVE MECHANIC 
 
 sails was quadruple the power of one horizontal sail, the 
 dimensions of each being the same. Taking this circum- 
 stance into the account, we cannot be far wrong in saying 
 that, in theory at least, if not in practice, the power of a 
 horizontal windmill is about one-third or one-fourth of the 
 power of a vertical one, when the quantity of surface and the 
 form of the sails are the same, and when all the parts of the 
 horizontal sails have the same distance from the axis of 
 motion as the corresponding parts of the vertical sails. But 
 if the horizontal sails have the position A I, E G, in fig. 1.51, 
 instead of the position C A c? wz, CD on, their effect will be 
 greatly increased, though the quantity of surface is the same \ 
 because the part C P 3 m being transferred to B I 3 c?, has 
 much more power to turn the sails. Having this method, 
 therefore, of increasing the effect of horizontal sails, which 
 cannot be applied to vertical ones, we would encourage every 
 attempt to improve their construction, as not only laudable 
 in itself, but calculated to be of essential utility in a com- 
 mercial country. — See Dr. Brewster’s valuable Appendix to 
 Ferguson’s Lectures, 
 
 FLOUR-MILLS. 
 
 In fig. 152 we have given a section of a double flour-mill, 
 reduced from Gray’s Experienced Mill- wright, with the follow- 
 ing account : 
 
 A A, the water-wheel. R B, its shaft or axle. C C, a wheel fixed uport 
 the same shaft, containing 90 teeth or cogs, to drive the pinion No. 1, 
 having 23 teeth, which is fastened upon the vertical shaft D. No. 2, a 
 wheel fixed upon the shaft D, containing 82 teeth, to turn the two pinions 
 F F, having 15 teeth, which are fastened upon the iron axles or spindles 
 that carry the two upper mill-stones. E E, the beam or sill that supports 
 the frame on which the under mill-stones are laid. G G, the cases or 
 boxes that enclose the upper mill-stones ; they should be about two inches 
 distant from the stone all round its circumference. XT, the bearers, called 
 bridges, upon which the under end of the iron spindles turn. These 
 spindles pass upwards through a hole in the middle of the nether mill-stones, 
 in which is fixed a wooden bush that their upper ends turn in. The top 
 part of the spindles, above each wooden bush, is made square, and goes 
 into a square hole in an iron cross, which is admitted into grooves in the 
 middle and under surface of the upper mill-stone. By this means that stone 
 is carried round along with the trundles F F, when turned by the wheel 
 No. 2. One end of the bridges TT is put into mortises in fixed bearers; 
 and the other end into mortises in the bearers that move at one end on iron 
 bolts, their other ends hanging by iron rods having screwed nuts, as UU; 
 so that when turned forward or backward they raise or depress the upper 
 mill-stones, according as the miller finds it necessary. S S, the feeders, in 
 the under end of each of which is a square socket that goes upon the square of 
 
JFX.'OHJM MUL.l 
 
 FI. 16 . 
 
 From ISQ to JS 4 
 
 i 
 
 lo6 
 
 154 
 
 Falc / jc j,v Jcmnd 
 
AND MACHINIST. 
 
 143 
 
 the spindles above the iron cross or rind, and having three or four branches 
 that move the spout or shoe, and feed the wheat constantly from the 
 hoppers into the hole or eye of the upper mill-stone, where it is introduced 
 betwixt the stones, and by the circular motion of the upper stone acquires 
 a centrifugal force, and proceeding gradually from the eye of the mill- 
 stone towards the circumference, is at length thrown out in flour or meal. 
 11 R, the sluice, machine, and handle, to raise the sluice, and let the water 
 on the wheel A to drive it round. No. 3 is a wheel fixed upon the shaft D, 
 containing 44 teeth, to turn the pinion No. 4, having 15 teeth, which is 
 fastened upon the horizontal axle H. On this axle is also fixed the 
 barrel K, on which go the two leather belts that turn the wire engine and 
 bolting mill. L, an iron spindle, in the under end of which is a square 
 socket that takes in a square on the top of the gudgeon of the vertical shaft 
 D. There is a pinion M, of nine teeth, fixed on the upper end of the 
 spindle L, to turn the wheel M M, having 48 teeth, which is fastened 
 upon the axle round which the rope Z Z rolls, to carry the sacks of flour up 
 to the cooling benches. By pulling the cord O O a little, the wheel M M 
 and its axle are put into motion, in consequence of that wheel and its axle 
 being moved horizontally, until the teeth of the wheel are brought into 
 contact with those of the pinion at the top of the spindle L : and, on the 
 contrary, by pulling the cord P P, the wheel M and its axle are moved in 
 the opposite horizontal direction, till they are thrown out of geer with the 
 pinion, and the rotatory motion of that wheel stops. But when the sack of 
 flour is raised up to the lever Q, it pushes up that end of the lever, and of 
 course the other end down ; by which means the pinion M is disengaged, 
 and thus that part of the machine stops of itself. N N are two large 
 hoppers, into which the clean wheat is put to be conveyed down to the 
 hoppers S S, placed on the frame immediately above the mill-stones. 
 W W, the side wall of the mill-house. V, the couples or frame of the roof. 
 X X, windows to lighten the house. 
 
 Fig. 153 represents the surface of the under grinding mill-stone; the way 
 of laying out the roads or channels ; the wooden bush fixed into the hole 
 in its middle, in which the upper end of the iron spindle turns round ; and 
 the case or hoops that surround the upper one, which ought to be two inches 
 clear of the stone all round its circumference. 
 
 Fig. 154, the upper grinding mill-stone, and iron cross or rind in its 
 middle; in the centre of which is a square hole that takes in a square on the 
 top of the iron spindle, to carry round the mill-stone. When the working 
 sides or faces of the mill-stones are laid uppermost, the roads (or channels) 
 must lie in the same direction in both ; so that when the upper stone is 
 turned over, and its surface laid upon the under one, then the channels may 
 cross eadi other, which assists in grinding and throwing oat the flour, the 
 sharp edges of the two furrows then cutting against each other like scissars. 
 The roads are likewise laid out according to the way the upper stone 
 revolves. In those represented in the figures, the running mill-stone is 
 supposed to turn “ sunway,’’ or as in what is called a right-handed mill : 
 but if the stone revolves the other way, the channels must be cut the reverse 
 of this, and then the mill is termed a left-handed one. 
 
 The mill-stones are of the utmost importance in the con- 
 struction of flour-mills, as upon them principally depends the 
 quality of the meal ; we cannot, therefore, do better than to 
 annex Mr. Ferguson’s opinion upon them, as also some sub- 
 sequent remarks by his editor. Dr. Brewster, 
 
144 
 
 THE OPERATIVE MECHANIC 
 
 MM.L SONE. 
 
 The heavier the running mill-stone is, and the greater the 
 quantity of water that falls upon the wheel, so much the 
 faster will the mill bear to be fed, and consequently, so much 
 the more it will grind : and, on the contrary, the lighter the 
 stone, and the less the quantity of water, so much slower 
 must the feeding be. But when the stone is considerably 
 wore, and become light, the mill must be fed slowly at any 
 rate ; otherwise the stone will be too much borne up by the 
 corn under it, which will make the meal coarse. 
 
 The quantity of power required to turn a heavy mill-stone 
 is but very little more than what is sufficient to turn a light 
 one : for as it is supported upon the spindle by the bridge-* 
 tree, and the end of the spindle that turns in the brass foot 
 therein being but small, the odds arising from the weight is 
 but very inconsiderable in its action against the power or 
 force of the water ; and, besides, a heavy stone has the same 
 advantage as a heavy fly, namely, that it regulates the motion 
 much better than a light one. 
 
 In order to cut and grind the corn, both the upper and 
 under mill- stones have channels or furrows cut into them, 
 proceeding obliquely from the centre towards the circum- 
 ference: and these furrows are cut perpendicularly on one 
 side, and obliquely on the other, into the stone, which gives 
 each furrow a sharp edge, and in the two stones they come, 
 as it were, against one another like the edges of a pair of 
 scissars, and so cut the corn, to make it grind the easier 
 when it falls upon the places between the furrows. These 
 are cut the same way in both stones when they lie upon their 
 backs, which makes them run cross ways to each other when 
 the upper stone is inverted, by turning its furrowed surface 
 toward that of the lower. For, if the furrows of both stones 
 lay the same way, a great deal of the corn would be driven 
 onward in the lower furrows, and so come out from between 
 the stones without being either cut or bruised. 
 
 When the furrows become blunt and shallow by wearing, 
 the running stone must be taken up, and both stones new 
 dressed with a chisel and hammer ; and every time the stone 
 is taken up, there must be some tallow put round the spindle 
 upon the bush, which will soon be melted by the heat the 
 spindle acquires from its turning and, rubbing against the 
 bush, and so will get in between them, otherwise the bush 
 would take fire in a very little time. 
 
 The bush must embrace the spindle quite close, to prevent 
 
and machinist. 
 
 145 
 
 
 nny shake in the motion, wliich would make some parts of 
 the stones grate and fire against each other, while other parts 
 of them would be too far asunder, and by that means spoil 
 the meal in grinding. 
 
 Whenever the spindle wears the bush so as to begin to 
 shake in it, the stone must be taken up, and a chisel drove 
 into several parts of the bush; and when it is taken out, 
 wooden wedges must be driven into the holes; by which 
 means the bush will be made to embrace the spindle close 
 all round it again. In doing this, great care must be taken 
 to drive equal wedges into the bush on opposite sides of the 
 spindle, otherwise it will be thrown out of the perpendicular, 
 and so hinder the upper stone from being set parallel to the 
 under one, which is absolutely necessary for making good 
 work. When any accident of this kind happens, the perpen- 
 dicular position of the spindle must be restored by adjusting 
 the bridge-tree by proper wedges put between it and the 
 brayer. 
 
 It often happens that the rind is a little wrenched in 
 laying down the upper stone upon it, or is made to sink a 
 little lower upon one side of the spindle than upon the other 5 
 and this will cause one edge of the upper stone to drag all 
 round upon the other, while the opposite edge will not 
 touch. But this is easily set to rights, by raising the stone 
 a little with a lever, and putting bits of paper, cards, or thin 
 chips, between the rind and the stone. 
 
 The diameter of the upper stone is generally about six 
 feet, the lower stone about an inch more; and the upper 
 stone, when new, contains about 22 J cubic feet, which 
 weighs somewhat more than 19,000 pounds. A stone of 
 this diameter ought never to go more than 60 times round 
 in a minute, for if it turns faster it will heat the meal. 
 
 The grinding surface of the under stone is a little convex 
 from the edge to the centre, and that of the upper stone a 
 little more concave : so that they are farthest from one 
 another in the middle, and come gradually nearer towards 
 the edges. By this means, the corn at its first entrance 
 between the stones is only bruised ; but as it goes farther on 
 towards the circumference or edge, it is cut smaller and 
 smaller; but at last finely ground just before it comes out 
 from between them.* 
 
 * The upper mill-stone, when six feet in diameter, is generally hollowed 
 about one inch at the centre ; and the under one rises about three-fourths 
 of an inch. The com that falls from the hopper insinuates itself between 
 them as far as two-thirds of the radius where the grinding begins ; the 
 
 L 
 
146 
 
 THE OPERATIVE MECHANIC 
 
 When the furrows of mill-stones are worn shallow, and 
 consequently new dressed with the chisel, the same quantity 
 of stone must be taken from every part of the j^rinding 
 surface, that it may have the same convexity or concavity as 
 before. As the upper mill-stone should always have the 
 same weight when its velocity remains unchanged, it will be 
 necessary to add to it as much weight as it lost in the dressing. 
 This will be most conveniently done by covering its top with 
 a layer of plaster, of the same diameter as the layer of stone 
 taken from its grinding surface, and as much thicker than 
 the layer of stone, as the specific gravity of the stone exceeds 
 the specific gravity of the plaster. That the reader may 
 have some idea of the manner in which the furrows, or 
 channels, are arranged, we have represented, fig. 154, the 
 grinding surface of the upper mill-stone, upon the supposition 
 that it moves from east to west, or for w^hat is called a right- 
 handed mill. When the mill-stone moves in the opposite 
 direction, the position of the furrows must be reversed. 
 
 In fig. 156, we have a section of the mill-stone, spindle, and lantern. 
 The under mill-stone M P H G, which never moves, may be of any 
 thickness. Its grinding surface must be of a conical form, the point b being 
 about an inch above the horizontal line P 11, and M a and P b being straight 
 lines. The upper mill-stone E F P M, which is fixed to the spindle C D, at 
 C, and is carried round with it, should be so hollowed that the angle 
 O M a, formed by the grinding surfaces, may be of such a size that O n, 
 being taken equal to n M, n s may be equal to the thickness of a grain of 
 corn. The diameter O N of the mill-eye m C, should be between 8 and 
 14 inches; and the weight of the upper mill-stone E P, joined to the 
 weight of the spindle CD, and the trundle x, (the sum of which three 
 numbers is called the eqiujmge of the turning mill-stone,) should never be 
 less than 1550 pounds avoirdupois, otherwise the resistance of the grain 
 would bear up the mill-stone, and the meal be ground too coarse. 
 
 In order to find the weight of the equipage; divide the third of the 
 radius of the gudgeon by the radius of the water-wheel which it supports, 
 and having taken the quotient from 2,25 multiply the remainder by the 
 expense of the source, by the relative fall, and by the number 19,911, and 
 you will have a first quantity, which may be regarded as pounds. Multiply 
 tlie square root of the relative fall by the weight of the arbor of the water- 
 wheel, by the radius of its gudgeon, and by the number 1617, and a second 
 quantity will be had, which will also represent pounds. Divide the third 
 part of the radius of the gudgeon by the radius of the water-wheel, and 
 having augmented the quotient by unity, multiply the sum by 1005, and a 
 third quantity will be obtained. Subtract the second quantity from the 
 first, divide the remainder by the third, and the quotient will express the 
 number of pounds in the equipage of the mill-stone. 
 
 The weight of the equipage being thus found, extract its 
 
 distance between the stones being there about two-thirds or three-fourths 
 of the thickness of a grain of corn. This distance, however, can be altered 
 at pleasure, by raising or sinking the upper stone. — Dr. Brewster. 
 
AND MACHINIST. 
 
 147 
 
 square root, expressed in pounds, and multiply it oy 039, 
 and the product will be the radius of the mill-stone in feet. 
 
 In order to find the weight and thickness of the upper mill- 
 stone, the following rules must be observed : 
 
 1. To find the weight of a quantity of stone equal to the mill-eye ; 
 take any quantity which seems most proper for the weight of the spindle 
 C D, and the lantern X, and subtract this quantity from the weight of the 
 mill-stone’s equipage, for a first quantity. Find the area of the mill-eye, 
 and multiply it by the weight of a cubic foot of stone of the same kind as 
 the mill-stone, and a second quantity will be had. Multiply the area of 
 the mill-stone by the weight of a cubic foot of the same stone, for a third 
 quantity. Multiply the first quantity by the second, and divide the product 
 by the third, and the quotient will be the weight required. 
 
 2. To find the number of cubic feet in the turning mill-stone, supposing 
 it to have no eye ; from the weight of the spindle and lantern subtract tlie 
 quantity found by the preceding rule, for the first number. Subtract this 
 first number from the weight of the equipage, and a second number will 
 be obtained. Divide this second quantity by the weight of a cubic foot of 
 stone of the same quality as the mill-stone, and the quotient will be the 
 number of cubic feet in E M P F, m C being supposed to be filled up. 
 
 3. To find the quantities wjN and EM, i.e. the thickness of the mill- 
 stone at its centre and circumference; divide the solid content of the 
 mill-stone, as found by the preceding rule, by its area, and you :\vill have 
 the first quantity. Add b R, which is generally about an inch, 'to twice 
 the diameter of a grain of corn, for a second quantity. Add the first 
 quantity to one-third of the second, and the sum will be the thickness of the 
 mill-stone at the circumference. Subtract the third of the second quantity 
 from the first quantity, and the remainder will be its thickness at the centre. 
 
 The size of the mill-stone being thus found, its velocity is 
 next to be determined. M. Fabre observes, that the flour 
 is the best possible when a mill- stone five feet in diameter 
 makes from 48 to 61 revolutions in a minute. Mr. Ferguson 
 allows 60 turns to a mill- stone six feet in diameter; and 
 Mr. Imison 120 to a mill- stone 4^ feet in diameter. In 
 mills upon Mr. Imison’s construction, the great heat that 
 must be generated by such a rapid motion of the mill-stone, 
 must render the meal of a very inferior quality : much time, 
 on the contrary, will be lost, when such a slow motion is 
 employed as is recommended by M. Fabre and Mr. Ferguson. 
 In the best corn-mills in this country, a mill-stone five feet 
 in diameter revolves, at an average, 90 times in a minute. 
 The number of revolutions in a minute, therefore, which must 
 be assigned to mill-stones of a different size, may be found 
 by dividing 450 by the diameter of the mill-stone in feet. 
 
 The spindle c D, which is commonly six feet long, may be made eitlier 
 of iron or wood. When it is of iron, and the weight of the mill-stone 
 7558 pounds avoirdupois, it is generally three inches in diameter; and 
 when made of v/ood, it is 10 or 11 inches in diameter. For mill-stones of 
 a different weight, the thickness of the spindle may be found by propot i 
 
 L 2 
 
THE OPERATIVE MECHANIC 
 
 148 
 
 tioning it to the square root of tlie mill-stone’s weight, or which is nearly 
 the same thing, to the weight of the mill-stone’s equipage. 
 
 The greatest diameter* of the pivot D, upon which the mill-stone rests, 
 should be proportional to the square root of the equipage, a pivot half an 
 inch diameter being able to support an equipage of 5398 pounds. In 
 most machines, the diameter of the pivots is by far too large, being capable 
 of supporting a much greater weight than they are obliged to bear. 'I'lie 
 friction is therefore increased, and tiie performance of the machine 
 diminished. 
 
 The bridge-tree, A B, is generally from 8 to 10 feet long, and should 
 always be elastic, that it may yield to the oscillatory motion of the mill- 
 stone. When its length is nine feet, and the weight of the equipage 5182 
 pounds, it should be six inches square ; and when the length remains 
 unchanged, and the equipage varies, the thickness of the bridge-tree should 
 be proportional to the square root of the equipage. 
 
 Although the mechanism of a flour-mill is exceedingly 
 simple, the profitable manufacture of flour requires consider- 
 able experience and attention. We shall therefore give a 
 sketch of the points most particularly to be attended to in 
 such manufacture. 
 
 The Avheats that grow in Essex and Kent make the best 
 flour. In choosing the wheat much attention should be paid 
 to the thinness of the skin and to its cleanliness from weed. 
 Good wheat may be known by its weight, which should be 
 about 62 pounds per Winchester bushel of 32 quarts. The 
 wheat to be manufactured into the best flour should be 
 winnowed. 
 
 The miller judges of the quality of the flour by feeling it, 
 and accordingly as it is too fine or too coarse regulates the 
 upper mill-stone, or increases or decreases the supply of 
 grain. The flour in grinding always acquires a slight warmth, 
 and care must be taken that the warmth does not increase, or 
 the flour will be permanently injured. 
 
 The dressing of the flour is of great importance, and too^ 
 much attention cannot be paid to it. The bran should be in 
 large flakes and free of flour. In grinding the best wheats, 
 in the best manner, the bran will amount to about seven 
 pounds per bushel. 
 
 In the process of dressing, the bran is examined as a 
 criterion to know whether too much flour be admitted upon 
 the machine. Care should be taken to have the brush screwed 
 close to the end of this machine. 
 
 French stones of about four feet in diameter are expected 
 to grind about five bushels per hour. 
 
 Mr. Thomas Fenwick, the autlior of Four Essays oc: Practical 
 Mechanics, has made numerous experiments on some of 
 the be'st mills for grinding corn, in order to form, by practical 
 observation, a set of tables illustrative of the cftect of a given 
 
’Fli'ors :^TELIaS 
 
 From 166 to 160 
 
 n.i7. 
 
 lo6 
 
 &St»iid^ jcJSt Strand 
 
AND MACHINIST. 14^? 
 
 quantity of water, in a given time, applied to an overshot- 
 wheel of a given size. 
 
 The quantity of water expended on the wheel was measured 
 with great exactness : the corn used was in a medium state 
 of dryness; the mills, in all their parts, were in a medium 
 working state; the mill-stones, making from 90 to 100 
 revolutions per minute, were from 4^ to 5 feet in diameter. 
 
 The result of the experiments was, that the power requisite 
 to raise a weight of 300 pounds avoirdupois, with a velocity 
 of 190 feet per minute, would grind one boll of good rye in 
 one hour ; but for the sake of making the following tables 
 hold in practice, where imperfection of construction exists 
 in some small degree, he took it at 300 pounds raised with 
 a velocity of 210 feet per minute, (being -rVth more,) and 
 for grinding two, three, four, or five bolls j3er hour, requires 
 a power equal to that which could raise 300 pounds with 
 the velocity of 350, 506, 677^ or 865 feet per minute respec- 
 tively. The difference of the power requisite to grind equal 
 quantities of wheat to that for rye will be very trifling. 
 
 To enable the young mechanist to understand the applica- 
 tion of his principles, he adds, as an illustration, that that 
 number of horses, or other applied power, which, by means 
 of a rope (considered as without weight) passing over a 
 single pulley placed over the mouth of a pit or well, can 
 raise out of it a load of 300 pounds avoirdupois, at the rate 
 of 210 feet per minute, will be sufficient to grind one boll of 
 corn per hour; and that a power which, in similar circum- 
 stances, can raise the same weight of 300 pounds with a 
 velocity of 350 feet per minute, will be able to grind two 
 bolls of corn per hour, and so on. 
 
 Having made some experiments to ascertain the friction 
 of a mill, when going with velocity sufficient to grind two 
 bolls of corn per hour, he relates the manner in which he 
 made them, that the reader may be able to judge of the 
 accuracy of his deductions. 
 
 The mill was made quite clear of corn, and the upper 
 mill-stone raised so that it would touch as little as possible 
 on the under stone in its revolutions; then such a quantity 
 of water was admitted to flow on the water-wheel, as to give 
 the mill, when empty, the same velocity it had when grinding 
 corn at the rate of two bolls per hour, which quantity of 
 water was sufficient to raise a load of 300 pounds with 
 a velocity of 100 feet per minute, which was therefore con- 
 sidered by him as the measure of the friction. Now as the 
 power requisite to grind two bolls of corn per hour, including 
 
150 
 
 THE OPERATIVE MECHANIC 
 
 the friction of the mill, is equal to that which can raise 
 a weight of 300 pounds with a velocity of 350 feet per 
 minute, and the friction of the moving parts of the mill is 
 equal to a power which would raise 300 pounds with a 
 velocity of 100 feet per minute ; therefore the difference of 
 the two, which is 300 pounds raised with the velocity of 
 250 feet per minute, is equal to the power employed in the 
 actual grinding of the corn, which is about two- thirds of the 
 whole. 
 
 The power equal to raise a weight of 300 pounds avoir- 
 dupois, with a velocity of 390 feet per minute, will prepare 
 properly one ton of old rope per week, for the purpose of 
 making paper: and, for preparing in like manner, two tons 
 of the same kind of materials per week, requires a power 
 equal to raise 300 pounds with a velocity of 525 feet per 
 minute, the mill working from 10 to 12 hours per day. 
 
 Tables^ showing the quantity of water (ale measure) re- 
 quisite to grind different quantities of corn, from one 
 to Jive bolls (Winchester measure ) per hour, applied on 
 overshot water-wheels from 10 to defect diameter; also 
 the size of the cylinder of the common steam-engine to 
 do the same work. ' 
 
 The water-wheel, 10 feet 
 diameter. 
 
 The water-wheel, 11 feet 
 diameter. 
 
 Bolls of 
 
 Quantity of 
 
 Diameter of 
 
 Bolls of 
 
 Quantity of 
 
 Diameter of 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 ground 
 
 site, in ale 
 
 a steam-engine 
 
 ground 
 
 site, in ale 
 
 a steam-engine | 
 
 per 
 
 gallons, per 
 
 to do the same 
 
 per 
 
 gallons, per 
 
 to do the same 
 
 hour. 
 
 minute. 
 
 work, in inches. 
 
 hour. 
 
 minute. 
 
 work, in inches. 
 
 1 
 
 786 
 
 12-5 
 
 1 
 
 705 
 
 12-5 
 
 H 
 
 1056 
 
 14-6 
 
 4 
 
 945 
 
 14-6 
 
 2 
 
 1341 
 
 16-75 
 
 2 
 
 1188 
 
 16-75 
 
 
 1617 
 
 18-5 
 
 
 1454 
 
 18-5 
 
 3 
 
 1894 
 
 20-2 
 
 3 
 
 1723 
 
 20-2 
 
 31 
 
 2220 
 
 21-75 
 
 34 
 
 2014 
 
 21-75 
 
 4 
 
 2541 
 
 23-25 
 
 4 
 
 2306 
 
 23-25 
 
 4i 
 
 2891 
 
 24-75 
 
 41 
 
 2626 
 
 24-75 
 
 5 
 
 3242 
 
 26-25 
 
 5 
 
 2944 
 
 26-25 
 
AND machinist. 
 
 15i 
 
 The water-wheel, 12 feet 
 
 The water-wheel, 14 feet 
 
 
 diameter. 
 
 
 diameter. 
 
 Bolls of 
 
 Quantity of 
 
 Diameter of 
 
 Bolls of 
 
 Quantity of 
 
 Diameter of 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 ground 
 
 site, in ale 
 
 a steam-engine 
 
 ground 
 
 site, in ale 
 
 a steam-engine 
 
 per 
 
 gallons, per 
 
 to do the same 
 
 per 
 
 gallons, per 
 
 to do the same 
 
 hour. 
 
 minute 
 
 work, in inches. 
 
 hour. 
 
 minute. 
 
 work, in inches. 
 
 1 
 
 655 
 
 12-5 
 
 1 
 
 564 
 
 12-5 
 
 n 
 
 873 
 
 14-6 
 
 14 
 
 740 
 
 14-6 
 
 2 
 
 1091 
 
 16-75 
 
 2 
 
 927 
 
 I6-75 
 
 n 
 
 1343 
 
 18-5 
 
 24 
 
 1140 
 
 18-5 
 
 3 
 
 1576 
 
 20-2 
 
 3 
 
 1353 
 
 20-2 
 
 
 1840 
 
 2175 
 
 34 
 
 1583 
 
 21-75 
 
 4 
 
 2117 
 
 23-25 
 
 4 
 
 1811 
 
 23-25 
 
 44 
 
 2408 
 
 24-75 
 
 44 
 
 2060 
 
 24-75 
 
 5 
 
 2700 
 
 26-25 
 
 5 
 
 2306 
 
 26-25 
 
 , The water-wheel, 13 feet 
 
 The water-wheel, 15 feet 
 
 
 diameter 
 
 
 diameter. 
 
 Bolls, 
 
 per 
 
 hour. 
 
 Water, 
 gallons per 
 minute. 
 
 Cylinder, in 
 inches. 
 
 Bolls, 
 
 per 
 
 hour. 
 
 Water, 
 gallons per 
 minute. 
 
 Cylinder, in 
 inches. 
 
 1 
 
 606 
 
 12-5 
 
 1 
 
 535 
 
 12-5 
 
 14 
 
 806 
 
 14-6 
 
 14 
 
 710 
 
 14-6 
 
 2 
 
 1009 
 
 I6-75 
 
 2 
 
 894 
 
 I6-75 
 
 24 
 
 1234 
 
 18-5 
 
 24 
 
 1090 
 
 18-5 
 
 3 
 
 1458 
 
 20-2 
 
 3 
 
 1290 
 
 20-2 
 
 34 
 
 1705 
 
 21-75 
 
 34 
 
 1503 
 
 21-75 
 
 4 
 
 1952 
 
 23-25 
 
 4 
 
 1717 
 
 23-25 
 
 44 
 
 2223 
 
 24-75 
 
 44 
 
 1967 
 
 24-75 
 
 5 
 
 2494 
 
 26-25 
 
 5 
 
 2211 
 
 26-25 
 
152 
 
 THK orERATJVE MECHANIC 
 
 ! The water-wheel. 16 feet 
 
 The water-wheel, 18 feet 
 
 
 diameter. 
 
 
 diameter. 
 
 i 
 
 j Bolls ol 
 
 Quantity of 
 
 Diameter of 
 
 Bolls of' 
 
 Quantity of 
 
 Diameter of 
 
 • corn 
 
 water requi- 
 
 the cylinder of 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 1 ground 
 
 site, in ale 
 
 a steam-engine 
 
 ground 
 
 site, in ale 
 
 a steam-engine 
 
 1 per 
 
 gallons, per 
 
 to do the same 
 
 per 
 
 gallons, per 
 
 to do the same 
 
 1 hour. 
 
 minute. 
 
 work, in inches. 
 
 hour. 
 
 minute. 
 
 work, in inches. 
 
 1 
 
 491 
 
 12-5 
 
 1 
 
 410 
 
 12-5 
 
 1 u 
 
 650 
 
 14-6 
 
 H 
 
 595 
 
 14-6 
 
 ! 2 
 
 811 
 
 16-75 
 
 2 
 
 730 
 
 I6-75 
 
 
 993 
 
 18-5 
 
 24 
 
 860 
 
 18-5 
 
 1 3 
 
 1176 
 
 20-2 
 
 3 
 
 1054 
 
 20-2 
 
 j 
 
 1380 
 
 21*75 
 
 34 
 
 1227 
 
 21-75 
 
 4 
 
 1582 
 
 23 25 
 
 4 
 
 1400 
 
 23-25 
 
 44 
 
 1802 
 
 24*75 
 
 
 1600 
 
 24-75 
 
 5 
 
 2023 
 
 26-25 
 
 5 
 
 1800 
 
 26-25 
 
 i 
 
 water- wheel, 17 feet 
 
 The water-wheel, 19 feet 
 
 j The 
 1 
 
 diameter. 
 
 
 diameter. 
 
 1 
 
 Bolls, 
 
 per 
 
 Water, 
 gallons per 
 
 Cylinder, in 
 inches. 
 
 Bolls, 
 
 per 
 
 Water, 
 gallons per 
 
 Cylinder, in 
 inches. 
 
 liour. 
 
 minute. 
 
 hour. 
 
 minute. 
 
 1 
 
 458 
 
 12-5 
 
 1 
 
 411 
 
 12-5 
 
 li 
 
 628 
 
 14*6 
 
 14 
 
 550 
 
 14-6 
 
 2 
 
 770 
 
 16-75 
 
 2 
 
 690 
 
 16-75 
 
 24 
 
 943 
 
 18-5 
 
 24 
 
 845 
 
 18-5 
 
 3 
 
 1117 
 
 20-2 
 
 3 
 
 1000 
 
 20-2 
 
 34 
 
 1300 
 
 21*75 
 
 34 
 
 1165 
 
 21*75 
 
 4 
 
 1482 
 
 23-25 
 
 4 
 
 1330 
 
 23-25 
 
 
 1695 
 
 24*75 
 
 44 
 
 1517 
 
 24*75 
 
 5 
 
 1906 
 
 26-25 
 
 5 
 
 1707 
 
 26-25 
 
AND MACHINIST 
 
 153 
 
 The water-wheel, 20 feet 
 
 ■ ■ ^ — f 
 
 The water-wheel, 22 feet 
 
 
 diameter. 
 
 
 diameter. 
 
 ' Bolls ol 
 
 Quantity of 
 
 Diameter of 
 
 Bolls oi 
 
 f Quantity of 
 
 1 
 
 1 
 
 Diameter of | 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 ground 
 
 site, in ale 
 
 a steam-engine 
 
 ground 
 
 site, in ale 
 gallons, per 
 
 a steam-engine 
 
 per 
 
 gallons, per 
 
 to do the same 
 
 per 
 
 *0 do the same 
 
 hour. 
 
 minute. 
 
 work, in inches. 
 
 hour. 
 
 minute. 
 
 work, in inches. 
 
 1 
 
 392 
 
 12-5 
 
 1 
 
 350 
 
 12-5 
 
 H 
 
 530 
 
 14-6 
 
 14 
 
 473 
 
 14-6 
 
 2 
 
 675 
 
 16-75 
 
 2 
 
 594 
 
 I6-75 
 
 
 808 
 
 18-5 
 
 24 
 
 722 
 
 18-5 
 
 3 
 
 945 
 
 20-2 
 
 3 
 
 860 
 
 20-2 
 
 34 
 
 1110 
 
 21-75 
 
 34 
 
 1007 
 
 21-75 
 
 4 
 
 12/0 
 
 23-25 
 
 4 
 
 1153 
 
 23-25 
 
 44 
 
 1445 
 
 24-75 
 
 44 
 
 1313 
 
 24-75 
 
 5 
 
 1623 
 
 26-25 
 
 5 
 
 1 
 
 1472 
 
 I 
 
 26-25 
 
 The water-wheel, 21 feet 
 
 The water-wheel, 23 feet 
 
 
 diameter. 
 
 
 diameter. 
 
 Bolls, 
 
 per 
 
 Water, 
 gallons per 
 
 Cylinder in, 
 inches. 
 
 Bolls, 
 
 per 
 
 1 
 
 Water, 
 gallons per 
 
 Cylinder, in 
 inches. 
 
 hour. 
 
 minute. 
 
 hour. 
 
 minute. 
 
 1 
 
 370 
 
 12-5 
 
 1 
 
 338 
 
 12-5 
 
 14 
 
 500 
 
 14-6 
 
 14 
 
 454 
 
 14-6 
 
 2 
 
 635 
 
 16-75 
 
 2 
 
 570 
 
 I6-75 
 
 24 
 
 767 
 
 18-5 
 
 -^2 
 
 3 
 
 707 
 
 18-5 
 
 3 
 
 900 
 
 20-2 
 
 - 824 
 
 20-2 
 
 34 
 
 1060 
 
 21-7o 
 
 34 
 
 964 
 
 21-75 
 
 4 
 
 1212 
 
 23-25 
 
 4 
 
 1124 
 
 23-25 
 
 44 
 
 1379 
 
 24-75 
 
 44 
 
 J258 
 
 24-75 
 
 5 
 
 1547 
 
 26-25 
 
 5 
 
 1412 
 
 26-25 
 
154 
 
 THE OPERATIVE MECHANIC 
 
 
 
 
 
 
 — — - — 
 
 The water-wheel. 24 feet 
 
 The water-wheel, 26 feet 
 
 
 diameter. 
 
 
 diameter. 
 
 Bolls o: 
 
 Quantity of 
 
 Diameter of 
 
 Bolls ol 
 
 : Quantity of 
 
 Diameter of 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 ground 
 
 site, in ale 
 
 a steam-engine 
 
 ground 
 
 site, in ale 
 
 a steam-engine 
 
 per 
 
 gallons, per 
 
 to do the same 
 
 per 
 
 gallons, per 
 
 to do the same 
 
 hour. 
 
 minute. 
 
 work, ill inches. 
 
 hour. 
 
 minute. 
 
 work, in inches. 
 
 1 
 
 327 
 
 12-5 
 
 1 
 
 303 
 
 12-5 
 
 1 2 
 
 436 
 
 14-6 
 
 14 
 
 403 
 
 14-6 
 
 2 
 
 545 
 
 16-75 
 
 2 
 
 504 
 
 I 6-75 
 
 2i 
 
 671 
 
 18-5 
 
 24 
 
 617 
 
 18-5 
 
 3 
 
 788 
 
 20-2 
 
 3 
 
 730 
 
 20-2 
 
 3i 
 
 920 
 
 21 -75 
 
 34 
 
 852 
 
 21-75 
 
 4 
 
 1050 
 
 23-25 
 
 4 
 
 975 
 
 23-25 
 
 
 1204 
 
 24-75 
 
 44 
 
 1111 
 
 24-75 
 
 
 1350 
 
 26.25 
 
 5 
 
 1247 
 
 26-25 
 
 The water-wheel, 25 feet 
 
 The water-wheel, 27 feet 
 
 
 diameter. 
 
 
 diameter. 
 
 Bolls, 
 
 per 
 
 j hour. 
 
 Water, 
 gallons per 
 minute. 
 
 Cylinder, in 
 inches. 
 
 Bolls, 
 
 per 
 
 hour. 
 
 Water, 
 gallons per 
 minute. 
 
 Cylinder, in 
 inches. 
 
 1 
 
 1 
 
 316 
 
 12-5 
 
 1 
 
 293 
 
 12-5 
 
 14 
 
 418 
 
 14-6 
 
 14 
 
 385 
 
 14-6 
 
 2 
 
 520 
 
 16-75 
 
 2 
 
 482 
 
 I 6-75 
 
 24 
 
 635 
 
 18-5 
 
 24 
 
 593 
 
 18-5 
 
 3 
 
 752 
 
 20-2 
 
 3 
 
 703 
 
 20-2 
 
 34 
 
 876 
 
 21-75 
 
 34 
 
 822 
 
 21-75 
 
 4 
 
 985 
 
 23-25 
 
 4 
 
 940 
 
 23-25 
 
 44 
 
 1150 
 
 24-75 
 
 44 
 
 1070 
 
 24-75 
 
 5 
 
 1300 
 
 26-25 
 
 5 
 
 1200 
 
 26-25 
 
AND MACHINIST 
 
 155 
 
 The water-wheel. 28 feet 
 
 The water-wheel, 30 feet j 
 
 
 diameter. 
 
 
 diameter. | 
 
 1 
 
 Bolls of 
 
 Quantity of 
 
 Diameter of 
 
 Bolls of 
 
 Quantity of 
 
 Diameter of { 
 
 corn 
 
 water requi- 
 
 the cylinder of 
 
 corn 
 
 water requi- 
 
 the cylinder of | 
 a steam-engine j 
 
 ground 
 
 site, in ale 
 
 a steam-engine 
 
 ground 
 
 site, in ale 
 
 per 
 
 gallons, per 
 
 ■to do the same 
 
 per 
 
 gallons, per 
 
 to do the same 
 
 hour. 
 
 minute. 
 
 work, in inches. 
 
 hour. 
 
 minute. 
 
 work, in inches. 
 
 1 
 
 282 
 
 i2-5 
 
 1 
 
 267 
 
 12*5 
 
 H 
 
 370 
 
 14-6 
 
 14 
 
 355 
 
 14*6 
 
 2 
 
 463 
 
 16*75 
 
 2 
 
 447 
 
 16*75 
 
 
 570 
 
 18*5 
 
 24 
 
 545 
 
 18*5 
 
 3 
 
 676 
 
 20*2 
 
 3 
 
 645 
 
 20*2 
 
 34 
 
 791 
 
 21*75 
 
 34 
 
 750 
 
 21*75 
 
 4 
 
 905 
 
 23*25 
 
 4 
 
 858 
 
 23*25 
 
 44 
 
 1030 
 
 24*75 
 
 44 
 
 983 
 
 24*75 
 
 5 
 
 1153 
 
 26*25 
 
 5 
 
 1106 
 
 26*25 
 
 The water-wheel, 29 feet 
 
 The water-wheel, 31 feet 
 
 
 diameter. 
 
 
 diameter. 
 
 Bolls, 
 
 per 
 
 hour. 
 
 Water, 
 gallons per 
 minute. 
 
 Cylinder, in 
 1 inches. 
 
 Bolls, 
 
 per 
 
 hour. 
 
 Water, 
 gallons per 
 minute. 
 
 Cylinder, in 
 inches. 
 
 1 
 
 274 
 
 12*5 
 
 1 
 
 256 
 
 12*5 . 
 
 14 
 
 363 
 
 14*6 
 
 14 
 
 340 
 
 14*6 
 
 2 
 
 455 
 
 . 16*75 
 
 2 
 
 426 
 
 16*75 
 
 24 
 
 557 
 
 18*5 
 
 24 
 
 520 
 
 18*5 
 
 3 
 
 660 
 
 20*2 
 
 3 
 
 620 
 
 20*2 
 
 34 
 
 770 
 
 21*75 
 
 34 
 
 717 
 
 21*75 
 
 4 
 
 880 
 
 23*25 
 
 4 
 
 827 
 
 23*25 
 
 44 
 
 1005 
 
 24*75 
 
 44 
 
 940 
 
 24*75 
 
 5 
 
 1130 
 
 26*25 
 
 5 
 
 1058 
 
 26*25 ! 
 
 1 
 
156 
 
 THE OPERATIVE MECHANIC 
 
 The water-wheel, 32 feet 
 diameter. 
 
 Bolls of 
 corn 
 ground 
 per 
 hour. 
 
 Quantity of 
 water requi- 
 site, in ale 
 gallons, per 
 minute. 
 
 Diameter of 
 the cylinder of 
 a steam-engine 
 to do the same 
 work, in inches. 
 
 1 
 
 245 
 
 12*5 
 
 n 
 
 325 
 
 14-6 
 
 2 
 
 406 
 
 1675 
 
 24 
 
 496 
 
 18*5 
 
 3 
 
 588 
 
 20-2 
 
 34 
 
 690 
 
 2175 
 
 4 
 
 791 
 
 23-25 
 
 41 
 
 900 
 
 24-75 
 
 5 
 
 1012 
 
 26-25 
 
 To make the foregoing tables applicable to mills intended 
 to be turned by undershot or breast water-wheels : from 
 Smeaton’s experiments it appears that the power required 
 on an undershot, water-wheel, to produce an effect equal to 
 that of an overshot (to which the tables are applicable,) is as 
 2*4 to one ; and also the power required on a breast water- 
 wheel, which receives the water on some point of its circum- 
 ference, and afterwards descends on the ladle boards, to 
 produce an equal effect with an overshot water-wheel, is as 
 175 to 1. 
 
AND MACHINIST. 
 
 157 
 
 A Table, shmving the necessary size of the cylinder of the 
 common steam-engine to grind different quantities of 
 corn, from 1 to 12 bolls (4 to 48 bushels Winchester 
 measure) per hour. 
 
 Bolls of 
 corn 
 ground 
 per 
 hour. 
 
 Diameter of 
 the cylinder of 
 a steam-engine 
 to do the same 
 work, in inches. 
 
 1 
 
 12-5 
 
 H 
 
 14-6 
 
 2 
 
 16-75 
 
 24 
 
 18-5 
 
 3 
 
 20-2 
 
 34 
 
 21-75 
 
 4 
 
 23-25 
 
 44 
 
 24-75 
 
 5 
 
 26-25 
 
 54 
 
 27-25 
 
 6 
 
 28-1 
 
 (34 
 
 29- 
 
 7 
 
 29-8 
 
 74 
 
 31-1 
 
 8 
 
 32- 
 
 81 
 
 33-3 
 
 9" 
 
 34-2 
 
 94 
 
 35-2 
 
 10 
 
 36- 
 
 104 
 
 37-3 
 
 11 
 
 38- 
 
 114 
 
 38-85 
 
 12“ 
 
 39-5 
 
 N. B. This table will be applicable to any improved 
 steam-engine, as well as that of the common kind^ if the ratio 
 of their efficacies be known. 
 
 APPLICATION OF THE TABLES. 
 
 Exampi.e I. — If a stream of water, producing 808 gallons, ale measure, 
 per minute, can he applied to an overshot water-wheel 20 feet diameter, 
 < 2 vhat quantity of corn will it be able to grind per hour? 
 
158 
 
 THFi OPERATIVE MECHANIC 
 
 Look in the tables under a 20 feet water-wheel, and opposite 808 gallons 
 will be found 2§ bolls of corn ground per hour. 
 
 Example II. — If a stream of water produchig SOS gallons, ale measure, 
 per minute, can he applied to an undershot water-wheel 20 feet diameter, 
 what quantity of corn can it grind per hour P 
 
 It is found by the tables, that, if applied on an overshot water-wheel 
 20 feet diameter, the stream will grind bolls per hour; and from 
 page 156, the power required by the undershot to that of the overshot 
 water- wheel, to produce an equal effect, is as 2*4 to 1 ; therefore, as 
 2-4:1: 2-5 : 1-04 bolls of corn ground per hour by means of the stream. 
 
 Example III. — If a stream of water, producing 808 gallons, ale measure, 
 per minute, can be applied on a breast water-wheel 20 feet diameter, what 
 quantity of corn can it grind per hour ? 
 
 It is found by the tables, that, if applied to an overshot water-wheel of 
 equal size, 2^ bolls of corn will be ground per hour; and from page 156, 
 the power of a breast water-wheel to that of an overshot water-wheel, to 
 produce an equal effect, is as 1-75 to 1 ; therefore, as 1-75 : 1 : ; 2-5 : 1-42 
 bolls of corn ground per hour by the stream. 
 
 Example IV. — Of what diameter must the cylinder of a common steam- 
 engine be made, to grind 10 bolls of corn per hour? 
 
 By looking on the table, page 157, opposite 10 bolls ground per hour, 
 the diameter of the steam cylinder will be found to be 36 inches. 
 
 FAMILY MILL AND BOLTER. 
 
 As a family mill and bolter cannot but be highly useful in 
 many situations, we shall give a description of one or two, 
 beginning with that invented by Mr. T. Rustall, of Purbrook- 
 heath, near Portsmouth, who received a premium of forty 
 guineas from the Society of Arts for his invention. 
 
 In fig. 157, A is the handle of the mill; B one of the mill-stones, 
 which is about 30 inches in diameter, and five inches in thickness, moving 
 with its axis C ; D is the other mill-stone, which, when in use, is stationary ; 
 but which may be placed near to or at a distance from the movable stone 
 B, by means of three screws passing through the wooden block E, that 
 supports one end of the axis C, after it has been put through a hole or 
 perforation in the-bed stone. The grain likewise passes through this 
 perforation, from the hopper F, into the mill. F represents the hopper, 
 which is agitated by two iron pins on the axis C, that alternately raise the 
 vessel containing the grain, which again sinks by its own weight. In 
 consequence of this motion the corn is conveyed through a spout that 
 passes from such hopper into the centre of the mill behind, and through 
 the bed-stone D. G, a paddle, regulating the quantity of corn to be 
 delivered to the mill, and by raising or lowering which, a larger or smaller 
 proportion of grain may, be furnished ; H, the receptacle for the flour, into 
 which it falls from the mill-stones, when ground ; I represents one of the 
 wooden supporters on which the bed-stone, D, rests. These are screwed 
 to the block E, and likewise mortised into the lower frame-work of the 
 mill at K, which is connected by means of the pins or wedges, L, L, L, 
 that admit the whole mill to be easily taken to pieces; M, a fly-wheel, 
 placed at the farthest extremity of the axis C, and on which another handle 
 may be occasionally fixed; N, a small rail, serving to keep the hopper in its 
 place, the furthest part of such hopper resting on a small pm, whicli 
 admits of sufficient motion for that vessel to shake forward the corn ; 0, 
 
AND MACHINIST. 
 
 159 
 
 a spur-rail, for strengthening tlie frame-work of the mill ; P, the front 
 upright, that is mortised into the frame-work, and serves as a rest for the 
 end of the iron axis C, which is next to the handle. On each extremity 
 of such axis there is a shoulder, which keeps it steady in its place. Lastly, 
 there is a cloth hood fixed to a broad wooden hoop, which is placed over 
 tlie stones while working, to prevent the finer particles of flour from 
 escaping. 
 
 Fig. 158 represents the bolter, with its front removed, in order to display 
 its interior structure ; the machine being 3 feet 10 inches in length, and 
 19§ inches in breadth, and 18 inches in depth. A is a movable partition, 
 sliding about four feet backwards or forwards from the centre of the box, 
 upon two wooden ribs, which are fixed to the back and front of the box, 
 and one of which is delineated at the letter B ; C, the lid of the bolter, 
 represented open ; D, a slider, which is movable in a groove made in tire 
 lid, by nreans of two handles in the back of such lid ; E, a forked iron, fixed 
 in the slider D, and which, when the lid is shut, takes hold of the sieve F, 
 and moves it backwards and forwards on the wooden ribs B, according to 
 the agitation of the slider; G represents a fixed partition in the lower centre 
 of the box, which it divides into two parts, in order to separate the fine 
 fi om the coarse flour ; from this partition the slider A moves each way 
 about four inches, and thus affords room for working the sieve ; II, a board 
 that is parallel to the bottom of the bolter, and forms part of the slider A ; 
 this board serves to prevent any of the sifted matter from falling into the 
 other partition; I represents two of the back feet which support the 
 bolter. 
 
 Fig. 159 is a view of the top or upper part of the lid of the bolter; R 
 the slider that moves the lengthwise of the bolter; LL the handles by 
 wliich the slider is worked ; M, a screw, serving to hold the fork, which 
 imparts motion to the sieve. 
 
 Fig. 160 represents the forked iron, E, separately from the lid. 
 
 Both the mill and bolter may be constructed at a moderate 
 expense, and they occupy only a small space of ground. 
 The former may even be worked in a public kitchen, or 
 within a room in a farm-house, without occasioning any 
 great encumbrance. 
 
 The particular excellence of this mill consists in this cir- 
 cumstance, that, from the vertical position of its stones, it 
 may be put in action without the intervention of cogs or 
 wheels. It may be employed in the grinding of malt, the 
 bruising of oats for horses, and for making flour, or for all 
 these purposes : it likewise may be easily altered, so as to 
 grind either of those articles to a greater or less degree of 
 fineness. 
 
 Another advantage peculiar to Mr. Rnstall’s contrivance 
 is, that one man is sufficient to w^ork it; though, if two 
 persons, namely, a man and a boy, be employed, they will 
 be able to produce, in the course of two hours, a quantity of 
 hour sufiicient to serve a family, consisting of six or eight 
 persons, for a wffiole week: — repeated satisfactory trials have 
 Ijioved that this mill grinds the corn completely, and at the 
 
THK OPERATIVE MECHANIC 
 
 I GO 
 
 rate of one biisliel of wheat within the hour. Besides, tlie 
 industrious farmer will thus he enabled to make comparative 
 experiments on the quality of his grain, and may furnish 
 himself, at a trifling expense, with flour from his own wheat, 
 without apprehending any adulteration, or without being 
 exposed to the impositions or caprice of fraudulent and 
 avaricious millers. 
 
 Lastly, though Mr. Rustairs bolter be more particularly 
 calculated for sifting flour, it may also be applied to various 
 other useful purposes, and especially with a view to obviate 
 the inconveniences necessarily attendant on the levigation of 
 noxious substances, and to prevent the waste of their finer 
 particles. 
 
 In order to reduce the labour in grinding, and to adjust 
 the power to the acquired force, and also to simplify mill- 
 making and grinding, and to reduce the expense attendant 
 upon them, so as to enable the farmer and housekeeper to 
 be independent of the miller’s system of grinding, Mr. George 
 Smart, of the Ordnance- wharf, Westminster-bridge, in April 
 1814, obtained a patent for certain improvements in machinery 
 for grinding corn, and various other articles,' by means of 
 which every article required to be broke or ground is exposed to 
 the application of rubbers or crushers, resting on their fulcrums, 
 and pressed against the revolving body by means of levers, 
 weights, or springs. The rubbers, or crushers, each acting 
 on a separate axle, will admit of any irregular surface, from 
 a square to a circle, to revolve against them, as each can 
 be loaded more or less, by moving the weights on the levers 
 further from, or nearer to, the fulcrum ; or, if with springs, 
 by screwing them more or less down. The rubbers or 
 crushers may be plain, grooved, circular sided, concave, or 
 any other figure best adapted for the substance to be broke 
 or ground. The square or octagon are best adapted for 
 breaking cement-stones, l)ones for manure, chalk, mixing 
 clay, mortar, &c. For breaking malt, beans, &c. one crusher 
 only is wanted; but for wheat, oats, barley, rice, or any jj 
 flour, or meal, the more rubbers or crushers the finer the 
 article will be ground; and the more flats there are on the 
 revolving body, the more crushers can be applied to advantage. 
 
 HAND-MILLS 
 
 Are most commonly used in grinding coffee and spices ; 
 but they are sometimes made of a larger size, and used to 
 grind wheat, malt, &c. ; in such cases the hand is generally 
 
AND MACHINIST. 
 
 161 
 
 applied to a winch handle. In Bockler’s Theatrum Ma^ 
 chinarum there is a description of a mill, in which the effort 
 of a man is applied to a lever moving to and fro horizontally, 
 nearly as in the action of rowing : as this is a very advan- 
 tageous method of applying human strength, the effort being 
 greatly assisted by the heaviness of the man in leaning 
 back, we shall give a brief description of it. 
 
 It is represented in fig. 161. The vertical shaft E G carries a toothed 
 wheel C, and a solid wheel F ; the latter being intended to operate as a 
 regulating fly. Upon the crank A B hangs one end of an iron I, the 
 other end of which hangs upon the lever H K, the motion being pretty free 
 at both ends of this bar I. One end of the lever H K hangs upon the fixed 
 hook K, about which, as a centre of motion, it turns. Then, while a man, 
 by pulling at the lever H K, moves the extremity H from H to N, the bar 
 I acting upon the crank A B gives to the wheels C and F half a rotation ; 
 and the momentum they have acquired will carry them on, the man at the 
 lever suffering it to turn back from N to II, while the other half of the rota- 
 tion of the w'heels is completed. In like manner another sufficient pull 
 at the lever H K gives another rotation to the wheel C, and so on, at 
 pleasure. The wheel C turns by its teeth the trundle D, the spindle of 
 which carries the upper mill-stone, just as the spindle D carries round the 
 upper mill-stone in ng. 156. In this mill the nearer the end of the bar I upon 
 the lever H K is to the fixed hook K, the easier, cceteris paribus, will the 
 man work the mill. If the number of teeth in the wheel C be six times 
 the number of cogs in the trundle D, then the labourer, by making ten 
 pulls at the lever H in a minute, will give sixty revolutions to the upper mill- 
 stone in the same space of time. 
 
 In the Transactions of the Society of Arts, may be seen 
 a description of a mill, invented by Mr. Garnett Terry, 
 of the City-road, for grinding hard substances, by means 
 of a wheel turning upon a horizontal axis instead of a 
 vertical one, as in the common construction. See hg. 162. 
 
 THE FOOT-MILL 
 
 Is used for grinding corn or any other substance, moved 
 by the pressure of the feet of men or oxen. A judicious 
 construction of the foot-mill is given in G. A. Bockler's 
 Theatrum Machinarum, 
 
 Tliis mill is represented in fig. 163. A is an inclined wheel, which is 
 turned by the weight of a man, and the impulsive force of his feet while 
 he supports himself, or occasionally pushes with his hands at the horizontal 
 bar H. The face of this wheel has thin pieces of wood nailed upon it at 
 proper distances, to keep the feet of the man from slipping while he pushes 
 the wheel round : and the under side has projecting teeth or waves which 
 :atch into the cogs of the trundle B, and by that means turn the horizontal 
 ?haft G with the wheel C : this latter wlieel turns the trundle D, the axle 
 jf which carries the upper mill-stone E. This kind of foot-mill will 
 insw'er extremely well to grind malt, 8cc. when no very great power is 
 ■equired. 
 
 M 
 
JG2 
 
 THE OPERATIVE MECHAMIC 
 
 KNEADING-MILL. 
 
 The business of grinding and baking is in one sense so 
 closely connected, that we shall in this place present a 
 description of the kneading-mill ; which is meant to do away 
 with that disgusting practice among bakers of kneading the 
 dough with their bare feet. It would be well if the legisla- 
 ture paid some attention to this, which is still carried on in 
 some parts of the metropolis, and particularly in the kneading 
 of dough for biscuits. 
 
 In the public baking-houses of Genoa a machine is used 
 which produces a great saving of time and labour. It was 
 first described in the Atti della Soeieta Patriotica di Milano^ 
 vol. ii. 
 
 A, in fig. 164, is a frame of wood which supports the axis of the machine: 
 a wall 14 palms high from the ground may be made use of instead of 
 this frame. B, a wall, palms thick, through which the aforesaid axis 
 passes. C, another wall, similar to the former, and facing it at the distance* 
 of 21 palms. D, the axis, 30 palms in length, and one palm and one-third 
 ill thickness. E, the great wheel, fixed to the said axis, between the frame 
 and the wall ; its diameter is 28 palms ; and its breadth, which is capable of 
 holding two men occasionally, is five palms. F, are steps, by treading on 
 which, the men turn the wheel very smartly ; they are two palms distant 
 from each other, and one-third of a palm in height. G, a small wheel with 
 cogs, fixed almost at the further extremity of the axis; its diameter is 
 12f palms. II, a beam of wood which extends from one wall to the other, 
 being 21 palms in length, and one and a third in thickness. A similar beam, 
 not seen in the figure, is on the opposite side of the axis. I, a transverse 
 piece of wood, placed near the wall C ; it is fixed into the two beams, and 
 serves to support the further extremity of the axis; its length is 14 palms, 
 and its thickness one and a third : there is likewise a transverse piece (which 
 cannot be seen in the figure) 14 palms long, and half a palm thick, placed 
 close to the wall B. K is a strong curved piece of oak, fixed transversely 
 in the side beams H, to receive the axis of the trundle: its length is 14 
 palms, and its thickness If. L is a trundle of 5f palms in diameter, 
 and If in height, which is moved by the cog-wheel G. M is a trundle 
 proceeding from the trundle L, and continued through the cross N to the 
 bottom of the tub P ; its centre is made of iron, partly scjuare and partly 
 round, and it turns in a socket of brass. The first part of this axis between 
 the trundle L and the cross N is of square iron, surrounded by two pieces 
 of wood, held together by iron hoops, which may be removed at pleasure 
 to examine the iron within ; its length is three palms, its diameter about 
 one palm. The second part of the axis which is within the tube, is made 
 like the first part; its length is If palm, its diameter 1^. The wooden 
 sheath of this part of the axis is fixed to the bottom of the tub, by the means 
 of three screws with their nuts. This axis is distant one-third of a palm 
 from the nearest triangular heater of the cross. N, the cross, formed of t^vo** 
 bars of wood unequally divided, so that the four arms of the cross are of 
 different lengths : one of the two pieces of wood of which the cross is made, 
 is six palms in length, the other five ; their' thickness is ~i of a palm, 
 

 sc.SSzStfxin^ 
 
AND MACHINIST. 
 
 163 
 
 and their breadth one palm. O, four pieces of wood, called beaten, of a 
 triangular shape, fixed vertically into the extremities of, and underneath, 
 the arms of the fore-mentioned cross; they are palm in length, and half 
 a palm in thickness, and beat or knead the dough in the tub at unequal 
 distances from the centre. P is a stout wooden tub, about a quarter of a 
 palm thick, well hooped with iron; its diameter is six palms, its height in 
 the clear. Fig. 165 is a box or trough of wood, four palms long, and 
 three wide, in which the leaven is formed (in about an hour) in a stove, and 
 in which it is afterwards carried to the tub P. Fig. 166 exhibits a view of 
 the trundle, cross, &c. with a section of the tub. Fig. 167 is a bird’s-eye view 
 of the cross and tub, with the upper ends of the triangular beaters. This tub 
 P will contain about 18 rubbi (about 19 bushels) of flour, which is carried 
 to it in barrels : the leaven is then carried to it in the box or trough, and 
 when the whole is tempered with a proper quantity of warm water, the 
 men work in the wheel till the dough is properly and completely kneaded. 
 In general a quarter of an hour is sufficient to make very good dough ; but 
 an experienced baker, who superintends, determines that the operation 
 shall be continued a few minutes more or less, according to circumstances. 
 
 The measures in the preceding description are given in 
 Genoese palms^ each of which is very nearly equal to 9.85 
 of our inches. The machinery may be varied in its construc- 
 tion according to circumstances, and the energy of the first 
 mover much better applied than by men walking in a common 
 wheel. 
 
 In November, 1811, a patent was granted to Mr. Joseph 
 Baker, navy contractor, for a method of kneading dough by 
 means of machinery. The invention consists in having an 
 upright shaft, turning on a pivot, fixed in tlie centre of a 
 circular trough, so that the dough placed in such trough may 
 be kneaded by a stone or iron roller, on its edge, passing 
 over it. in a rotatory motion, being fixed at a due distance by 
 an horizontal bar or axle to the shaft, which is to be turned 
 by means of one or more other horizontal bars likewise fixed 
 thereto, and worked like a capstan by a proportionate number 
 of bipeds or quadrupeds, such horizontal bars having small 
 shares fixed to them, so as to run in the trough, and, acting 
 like a plough, cause the dough to present fresh surfaces for 
 each successive revolution. 
 
 Independent of the methods above quoted, many others 
 might easily be adapted, to do away with the filthy practice 
 to which we have alluded. 
 
164 
 
 THE OPERATIVE MECHANIC 
 
 THE STEAM-ENGINE. 
 
 The most prominent feature in modern discovery is tlie 
 steam-engine, which has, with much propriety, been deno- 
 minated the noblest monument of human ingenuity.” The 
 Marquis of Worcester, who lived in the reign of Charles II., 
 is entii^led to the honour of having first directed the attention 
 of mankind to the expansive force of steam when used in a 
 close vessel: but in the book published by him in 1663, he is 
 not sufficiently explicit or intelligible, for us to determine 
 what kind of apparatus, or combination of machinery, was 
 used by him for the guidance of its powers. It is however 
 but reasonable to suppose, notwithstanding the vagueness of 
 his expressions, that it was principally owing to the direction 
 his observations gave to the minds of others that steam began 
 to be used as a first mover of machinery. 
 
 When water is exposed to the action of heat, it expands 
 and assumes the gaseous state called steam. When it is 
 confined in a close vessel, and heat is applied to it, the 
 quality of expansion is exerted to a powerful extent j and as 
 the space between the top of the water and the top of the 
 vessel is filled with atmospheric air, the first portion of the 
 power, exerted by the expansion of the steam, is directed 
 towards the displacing of that atmosphere from the situation 
 which its weight had assigned it, and, consequently, such 
 portion of the direct action of the expansive force of steam 
 is to be deducted from its disposable power. Tliis portion 
 of power is, however, ultimately available. For as by a 
 reduction of temperature steam reassumes the state of water, 
 leaving the space which it had occupied again void, the 
 atmosphere which it had displaced returns to its former 
 situation, exerting a force, so to do, exactly tantamount to 
 that which the steam had exerted to displace it. This force 
 may be termed the consequent power of steam. The direct- 
 ing and controlling of these powers, so that they may be 
 applied to the purpose of creating equable motion, is the 
 object attained almost to perfection in the steam-engine: and 
 it is the more accurate control, the more advantageous 
 application, and the more economic production of these 
 powers, that have been aimed at in its various modifications. 
 
 For more perfectly illustrating the mode in which steam operates we will 
 suppose the vessel, represented at fig. 168, to be filled with water up to 
 the line A, and the space E occupied with air, and having a plug or piston 
 fitting it at C, and an aperture at D; now if the aperture I) be closed, and 
 
AND MACHINIST. 
 
 165 
 
 heat applied to the water, as at F, steam will be generated, and by its 
 expansive force will raise the piston C upwards ; then if the heat be w'ith- 
 drawn and the vessel suddenly cooled, condeusatioii will take place ; the 
 steam, reassuming the form of water, will again occupy the space below 
 the line A, and the piston C will return to its place. In this experiment 
 the expansive force of the steam compressed the air in the space E, and 
 forced the plug C upwards, we will suppose, to H ; but C, in travelling to 
 H, displaced so much of the atmosphere as occupied the tube from C to H ; 
 consequently, the portion so displaced will seek to resume its natural 
 position, and when the force of the steam is withdrawn by condensation, 
 the weight of that portion of the atmosphere will again return the plug C 
 to its place ; by which, it is obvious, that the raising of the plug w'as the 
 direct action of the steam, and the returning its consequent action, or 
 the action of the atmosphere in consequence of its having been displaced 
 by the force of the steam. 
 
 Again, if we suppose the plug to be in its first situation, as at C, and w'e 
 open the aperture at D, and apply heat, the steam will rise into the space 
 K, and expel the air through the aperture D, w'hich being closed, and 
 condensation caused, the space E will be left a vacuum, and the atmo- 
 sphere seeking to occupy that space will force the plug C down to the line 
 A ; here the movement of the plug C w^as solely caused by the atmosphere 
 exerting itself to regain the position whence it had been expelled by the 
 force of the steam through D, and this eft'ect is performed by the conse- 
 quent power of steam alone. 
 
 It has been found by experiments, that the pressure of the atmosphere is 
 equal to about 14 pounds weight upon every square inch, so that sup- 
 posing the superficies of the aperture of the vessel, fig. 168, to contain one 
 square inch, the power exerted by the steam in raising C to II will be 
 tantamount to raising 14 pounds weight that height, together with the 
 power necessary to overcome the friction and w^eight of the piston C, in 
 the cylinder; and, that the power exerted by the steam in expelling the 
 atmosphere from the space E, and obtaining its consequent pressure to the 
 raising of 14 pounds from A to C ; and that the disposable power, obtained 
 by the return of the piston from H, will, in the first instance, be equal to the 
 raising of 14 pounds weight from C to H, less the amount of the friction of the 
 piston C ; and, in the second, will be equal to the raising of 1 4 pounds weight 
 from C to A, less the amount of the friction as before. In both these instances 
 the expansive or direct force of the steam has only been considered as equal 
 to the displacing of the atmosphere, or what will be equal to 14 pounds 
 pressure on each superficial inch ; but if the piston C be loaded with any 
 weight, the steam will, if urged with sufficient heat, raise it, always premising 
 that the vessel is strong enough to resist the increased pressure. Suppose 
 C to be loaded with 10 pounds of weight, the steam must be urged until its 
 pressure is equal to 24 pounds, 10 pounds more, 14 pounds the pressure 
 of the atmosphere on each square inch, and the resulting disposable force 
 will be equal to 24 pounds more, the weight of C, less its friction return- 
 ing to the place from where C was raised ; so that, in this case, the pressure 
 on the internal sides of the vessel, tending to burst it, will be equal to 
 10 pounds per square inch of the internal superficies, the remaining 
 14 pounds being counteracted by the pressure of the atmosphere on the 
 external surface, which is equal to 14 pounds of the internal pressure. By 
 this, it is evident, that the direct force of steam may be increased without 
 limits, whereas the resulting force or pressure of the atmosphere is mani- 
 festly bounded to 14 or 15 pounds qn the square inch according as its 
 density varies. 
 
THE OPERATIVE MECHANIC 
 
 IVusting from this explaiiiition that even those who are 
 miacqiiainted with matters of this nature will clearly compre- 
 ]';end the manner in which the expansive force of steam 
 operates, we sluill proceed to explain the different mechanical 
 combinations which have been formed to render this power 
 subservient lo oiir will : premising that what we have hereto- 
 fore called the consequent power of steam wdll, in future, be 
 considered the pressure of the atmosphere, which in fact 
 it is, having adopted the other term in the introductory 
 explciiiation, in order more clearly to impress on the mind, 
 that the expansive force of steam is actually the only originator 
 of power in this machine. 
 
 The first apparatus with which we ?n*e acquainted, con- 
 structed for the purpose of employing steam as power to act 
 in a close vessel, was invented by a Captain Savary, for 
 which, in the year 1698, he obtained a patent. The form of 
 it, as invented by him, is represented in fig. 169 . 
 
 :.i close boiler, placed on a furnace, and of sufficient strength to resist 
 considerable pressure; B another vessel strongly constructed ; cc a pipe with 
 a cock in it at ?, by means of which a communication can be made from a to B 
 at pleasure; c a pipe proceeding downwards into a well or other reservoir of 
 water; ff another pipe proceeding from B to a reservoir placed above; 
 h k is a pipe communicating from B to the pipe //, and having a cock in 
 it at k to allow of, or cut oft’, such cotumunication ; m is a valve capable of 
 clo’sing the pipe e by pressure from above, and of opening it by pressure 
 from below ; I a similar valve fitted to the pipe /y, and capable of being 
 acted upon in a similar manner. If the boiler a be filled with water to the 
 dotted line, and heat applied by means of the furnace, the steam will rise 
 in tlie boiler, mid, passing through the pipe c c, fill the vessel B, and pass 
 up the pipey/; the valve wbeing shut by the expansive force of the steam 
 pressing upon it ; if the cock i be now shut and the steam in the vessel B 
 condensed, by throwing cold water upon its outer surface, the atmosphere 
 pressing on the valve m will close it, and the interior of the vessel B remain 
 a vacuum, and the water in the reservoir to which the pipe e passes will be 
 forced by the external pressure of the atmosphere into the vessel B up to 
 the dotted line, which is supposed to be about 26 feet from the surface 
 of the v/ater in tlie reservoir, being the length of a column of water, which, 
 ■faking into account that the vacuum thus formed is not quite perfect, is 
 equal to the pressure that will be exerted by the atmosphere. If the cock 
 i be opened again, and the steam allowed to press on the surface of the 
 water, in B, it will close the valve m, and cause the water to ascend the 
 pipe ff, through the valve I, to the upper reservoir ; and when the cock i 
 is again shut, and the steam in B again caused to condense, the operation 
 will be repejfied, and the weight of the water in the pipe yywill close the 
 valve I, and cause the vessel B to be filled by e as before. 
 
 Such was tlie construction and mode of operating with the first apparatus 
 tnade by Captain Savary. But he, finding it inconvenient to cause con- 
 xlcnsation by means of throwing cold water upon the outer surface, introduced 
 the pipe h h into B, which, by opening the cock k, allowed some portion of 
 ihe svatcr to pass fiom the pipe ff, which was always full after the first 
 ;;lrukc, and thereby cause condensation more quickly to ensue. 
 
AND MACHINIST. 
 
 1G7 
 
 The trial or gauge cocks o, q, were also contrived by Captain Savary, in 
 order to ascertain the height of the water in the boiler. If the surface of 
 the water is above the lower ends of the cocks, and the cocks be opened, 
 water will issue from them; if below, steam. But if the water is at its 
 proper level, that is to say, if the surface of the water be in the inter- 
 mediate space between the ends of the cocks q and n o, water will issue 
 from the former, and steam from the latter. This knowledge was neces- 
 sary to be obtained ; for should the surface of the water exceed the height 
 of tlie cocks 0, there will not be room for a sufficiency of steam to remain 
 in store for continued operation. 
 
 The application of this engine was confined to the raising 
 of water to small heights, as it operated only by atmospheric 
 pressure ; in deep mines it w^as found not to be effective. Tak- 
 ing into consideration, however, the then imperfect state of 
 knowledge, so far as regarded steam as a first mover, the 
 inventor is entitled to no inconsiderable degree of praise for 
 this specimen of his ingenuity. The greatest objection to 
 this mode is, the great waste of steam, and consequent 
 unnecessary expenditure of fuel, arising from the condensa- 
 tion being effected by allowing cold water to come into 
 contact with the steam in the vessel B. 
 
 At the time when the existence of this engine was first 
 made known to the public, tlie amazing pow’er of steam, 
 which it so plainly demonstrated, began very deservedly to 
 obtain the attention of ingenious men; and disputes for the 
 honour of the discovery took place, the English ascribing it 
 to the Marquis of Worcester, the French to Papin. 
 
 Without entering into the minutiae of this contest, it will 
 be sufficient for us to trace progressively the grand improve- 
 ments that have taken place in the steam-engine in this 
 country: though not forgetting to mention the accessary 
 improvements derived from foreign aid. Of this latter is the 
 safety valve, an instrument, though in itself simple, of such 
 vast importance, that to it may be attributed the general 
 introduction, and consequent improvement, of the steam-engine 
 to its present existing state of perfection. It was contrived 
 by Dr. Papin, wdio, at the time of Captain Savary’s invention, 
 was making experiments on the power of steam at high 
 temperatures, for the purpose of dissolving bodies. It con- 
 sists merely of an aperture of a specific dimension, suppose, 
 for instance, one square inch, in or communicating with any 
 close boiler, and a valve properly fitted in that aperture, such 
 valve being on the outside loaded to any extent considered 
 necessary to resist the force of the steam until it has 
 acquired a certain degree of power, computed to be what the 
 boiler is perfectly capable of sustaining without the chance of 
 bursting. Now it is manifest, until the pressure of the steam 
 
168 
 
 THE OPERATfVE MECHANIC 
 
 Avithin has exerted itself so far as to raise such weight, the 
 internal pressure per square inch, tending to burst the boiler, 
 does not exceed the amount of such weight, so that, by this 
 means, an estimate of the chances of such an occurrence 
 taking place can easily be made. 
 
 The contrivance by Dr. Papin, of placing a piece of wood 
 to float upon the surface of the water, though an improve- 
 ment in this stage of the engine, is now of no importance: 
 but it is not improbable, that this flrst suggesl*ed the idea of 
 a close fitted piston working in a cylinder, which constituted 
 the most valuable part in the next step of advancement. 
 This Avas effected by an ironmonger or smith of the name of 
 NeAvcomen, and a glazier of the name of Cauly, residing at 
 Dartmouth, in Devonshire, Avho were contented to share the 
 profits of the invention with Savary, and jointly with him 
 obtained a patent for it in the year 1705. 
 
 This engine, generally called Newcomen’s engine, was the 
 first that had a piston fitted to work in a cylinder, which, 
 together with the beam, gave to the construction of the 
 machine a new character. 
 
 An engine upon this construction is represented in fig, 170, where A is 
 a boiler placed upon a furnace ; B, a cylinder, bored true, and having the 
 piston c fitted to work easily therein ; q, a cock in the pipe forming a com- 
 munication from the boiler to the lower part of the cylinder ; S, a safety 
 valve loaded by the weight at the extremity of the lever r pressing upon 
 the upright pin of the valve at « ,♦ d d, 2 i pipe leading from the cylinder B 
 to the reservoir i, with the cock e for opening and closing the connection; 
 / /, another pipe leading also from the cylinder to the reservoir h, having a 
 valve at the lower extremity, opening outwards, for the purpose of allowing 
 any accumulation of condensed water in the cylinder to run off, and 
 through which the air may be ejected by the steam when filling B; LL is 
 a beam, supported upon the wall K K, and capable of vibrating upon the 
 centre IJ ; a is the rod of the piston, fastened to the curved end of the beam 
 by a chain ; m m the rod of the pump, fixed to the beam in a manner 
 similar to the piston rod; the pump is placed in the well or pit a;, with 
 the weights o o hanging upon the pump rods sufficient to counter- 
 balance the piston and rod on the other end of the beam, and keep it raised 
 to the top of the cylinder ; is a pipe leading from the pump in the well 
 to supply the cistern i. 
 
 Supposing the piston c to be in the situation cb near the top of the 
 cylinder, and the steam in the boiler to be urged by fire in the furnace, and 
 the cock q to be open, the cylinder B will become filled with steam, and 
 the air that is in it be expelled by the pipe//, and through the clack-valve 
 at the end, which, from the noise made by such expulsion is called the 
 snifting-clack. If the cock q be closed, and that at e opened, water will 
 rush from the reservoir i into the cylinder, and by causing an immediate 
 condensation of the steam create a vacuum, so that the pressure of the 
 atmosphere will operate upon and force down the piston c to the bottom 
 of the cylinder, and cause the other end of the beam L to rise as much as 
 that end falls, which makes one stroke of the pump-rods. If the cock e be 
 pow closed, and q opened, gleam will force against the bottom of c, and by 
 
'v^TE AM( !EF(B]L^:E 
 From Ui8 to 17. ? 
 
 FI. 19. 
 
 168 E 
 
 170 
 
 > 
 
AND MACHINIST. 
 
 169 
 
 overcoming the pressure oi ihe atmosphere again raise it to its original 
 position ; and q being again closed, and e opened, the performance of a 
 similar operation will be effected. 
 
 The advantage sought in the construction of this sort of engine was 
 obtained, namely, that of not being required to use steam of greater 
 pressure than the atmosphere, which was the case in Savary’s engine, when 
 the height the water was to be raised by the pipe f fig. 169, exceeded 
 more than about 32 feet. In Newcomen’s engine, the weight o o balances 
 the piston c, and the exertion of the steam is never required to be more than 
 about 14 pounds to the superficial inch; w^hilst the introduction of the 
 beam affords a movement applicable to the working of pumps, by which 
 water can be raised to any required height. 
 
 The cocks q and e were opened by the hand of an attendant until a boy 
 of the name of Potter, who was intrusted with the management of them, 
 to save himself the labour and attention which they required, ingeniously 
 contrived to attach a piece of string to the levers of the cocks, and to the 
 beam L L, in such a manner, as to procure by its movement their being 
 opened and shut at the proper periods. It was this gave the idea for the 
 construction of that part of the present engine called hand-geer. 
 
 The next person who made any considerable improvement 
 in the steam-engine was Mr. Henry Beighton, of Newcastle, 
 who invented the part called the plug-tree, for opening and 
 shutting the valves, which we shall describe in a more 
 advanced part of the work : he also adopted a force-pump, to 
 supply the deficiency of water in the boiler caused by the 
 expenditure in the production of steam. This engine, called 
 Beighton’ s fire-engine^ was much used for nearly half a 
 century \ and the attention of engineers was directed more 
 towards the economizing of fuel, than the further improve- 
 ment of the engine. 
 
 At length, however, it began to be' perceived, that the 
 attainment of a rotatory motion would open an extensive 
 field for the application of its powers to various mechanical 
 purposes ; and, accordingly, we find the attention of engineers 
 most actively engaged in endeavouring to effect so desirable 
 an object, which was eventually accomplished by Mr. Matthew 
 Washbrough, of Bristol, who, in the year 177^, obtained a 
 patent for the application of the crank. Though this is by 
 far the best application that has been yet applied, as is 
 evident from its now almost universal adoption, it was for 
 some time superseded by the sun and planet wheels intro- 
 duced by Messrs. Boulton and Watt. 
 
 The sun and planet wheels are represented in fig. 171. A represents the 
 end of the beam, to which is affixed, by a movable centre at F, the rod B, 
 called the connecting rod, upon the lower end of which is immovably fixed 
 the wheel C ; D is a cog-wheel, fixed upon the axis of the fly-wheel 
 G G G G, and capable of revolving with it. When the beam A passes 
 downwards, the wheel C changes from its position at C to C\ and I's cogs, 
 acting upon those of the wheel D, cause that, and the fly-whes! to wliirh 
 
THE '>PERATIVE MECHANIC 
 
 170 
 
 it is attached, to perform that portion of a revolution round its axis. The 
 wheel C, from the manner in which it is suspended, tends always to press 
 against (3 in its downward and upward motions. When C is in the position 
 of C^, the wheel D, from the velocity it has acquired by its connection with 
 tlic fly-vdieel, causes it to pass under the centre of D, and the beam begin- 
 ning immediately to ascend, operates by C on the other side of D, giving it 
 another portion of impulse towards a continuous motion whilst passing 
 from to and when it arrives at C® it will be impelled over the centre- 
 D D by the velocity wliich its own action had given the fly-wheel. 
 
 The crank and fly-wheel invented by Mr. Matthew Washbrough is shown 
 in fig. 172. A and B represent the same parts as in fig. 171, but the lower 
 end of B is, in this case, attached to the crank C at c^, and is capable of 
 revolving round the centre E; the other end of the crank is attached to the 
 fly-wheel D D D D, so that both that and the fly-wheel are capable of 
 revolving round the centre E. When the beam A is depressed, it com- 
 municates motion to the crank and fly-wheel to which it is attached, and 
 when it arrives at H, the velocity of the fly-wheel causes it to pass under 
 the centre E, and the beam beginning immediately to ascend, again com- 
 municates motion to the fly-wheel. 
 
 The length of the connecting rod B should be such that 
 when the beam A is in an horizontal position, the crank will 
 likewise be the same; and when the crank is in the position 
 as at G, its length, together with the length of the crank, 
 such as to permit the other end of the beam. A, to descend 
 until the piston which is attached to it is at the bottom of 
 the cylinder; and the length of these and the cylinder such, 
 that when the crank is in the position H, the piston shall be 
 at the top of the cylinder. This method not only affords a 
 rotative motion, but determines the length of the stroke 
 which the piston may be required to perform, to an exactness 
 that is of great importance ; for prior to its introduction, the 
 forcible striking of the piston against the top and bottom of 
 the cylinder, which was attended with injurious effects, was' |j 
 an occurrence by no means unfrequent, and which the sun 
 and planet wheels were in no way calculated to remedy. 
 
 Watt, a native of Glasgow, having his attention ac- 
 cidentally directed to the construction of the steam-engine, 
 discovered that water, when confined in a close vessel, and^ 
 heated considerably beyond the boiling temperature, w’ould,'! 
 when the steam was permitted to escape, cool rapidly down 
 to the boiling point, which suggested an idea, that the I 
 amount of steam issuing from any vessel was simply in pro- | 
 portion to the amount of heat applied, and that the economiz- “ 
 ing of fuel could only be obtained by the economizing of 
 steam. Mr. Watt also noticed the great change which took place 
 in tlie temperature of the cylinder when the cold water was 
 injected to condense the steam; and concluded, that as the 
 coldness of the cylinder would remain after the necessary con- 
 
ANL> mac Hi NIST. 
 
 17 * 
 
 :lensation had been effected, a wasteful condensation of the 
 lewly introduced steam must take place. By experiment he 
 blind, that the quantity of steam thus wasted was no less than 
 hrice the contents of the cylinder, or three times the quan- 
 ;ity which was required for producing the effect sought. The 
 nodes to which he had recourse to remedy this defect were 
 irst, the substitution of a wooden cylinder, which, upon 
 repeated trials, he was compelled to abandon, on account of 
 .he roughness produced by wet and the changes of temper- 
 iture ; secondly, the enclosing of the cylinder with w’ood, and 
 filling the intermediate space with powdered charcoal ; which 
 ifterwards was superseded by the introduction of an extra 
 cylinder, that enclosed the working cylinder, and permitted 
 5 team to flow round it, which maintained it at a regular tem- 
 perature. The outer cylinder is termed a jacket, and is now 
 ised with advantage. 
 
 In the year 1J63, Mr. Watt made the grand improvement 
 )f effecting the condensation in a separate vessel, communi- 
 :ating only by a pipe to the cylinder, termed the condenser. 
 
 la fig. 178, A is the lower part of the cylinder; B the condenser ; C the 
 duction pipe, or pipe of communication between the cylinder and condenser, 
 apable of being opened or closed by the cock c ; and DD a chamber of cold 
 7ater, in which the condenser B is immersed. ^\^len the cock c is 
 pened, the steam, by its elastic force, rushes into B, where it is condensed ; 
 nd the space it has left in the cylinder allows a new supply of steam to be 
 enerated, which, by the opening of the cock c, also passes into B, and is 
 imilarly condensed. The condensing of the steam necessarily accumulates 
 /ater in B, and reduces the eapacity of the condenser; to remedy which, 
 Ir. Wat-t introduced a small pump, worked by the engine, to withdraw the 
 xtra water, as also the air, which in some degree hindered the perfectness 
 f the vacuum : he named it the air-pump. He also found it expedient to 
 ermit a small stream of water to run from the chamber DD, by means of a 
 ock, which could regulate the supply according to the temperature of the 
 /ater in D, or the required rapidity of the condensation. The cistern in 
 /hich the condenser is placed is called the cold-water cistern ; it is con- 
 nually being supplied with fresh water from a pump connected with a 
 .-ell or pit, and the overplus is discharged by a spout into a dram. The 
 ,ot water drawn from the condenser by the air-pump is delivered into 
 nother cistern, termed the hot-ivater cistern. 
 
 These parts are represented in fig. 174, where their distribution is such as 
 'i exhibit them conveniently without taking into view their construction in 
 ny particular engine, as their form and relative position is of no import- 
 nce, and is arbitrarily varied as the different builders think fit, or as con- 
 eniency or circumstances may in many cases require. A is the cylinder ; 
 )the condenser; C the air-pump; EE the cold-water cistern; F the cold- 
 '■ater pump for supplying the same ; SS the steam pipe from the boiler ; 
 1 the eduction pipe from the cylinder to the condenser ; OO the hot-water 
 istern ; N the injection cock for allowing a small stream of water to flow 
 ato B ; P the hot -water pump, which forces a sufficiency of water from the 
 ot-water cistern through the pipe ij- to keep up the supply in the boiler 
 
THE OPERATIVE MECHANIC 
 
 172 
 
 t tt t are pump rods, fixed to the beam and worked by its motion ; 5 * is a 
 suction pipe ; and m the foot-valve. The pipe I and the valve V, opening 
 upwards, are for the purpose of permitting the steam to pass through to 
 expel the atmosphere from the condenser, called a blow-valve, and then by 
 its own condensation to leave a vacuum on the starting of the engine. 
 
 A communication is made from the condenser by a pipe to the upper part 
 of a tube standing in a basin of mercury. The amount of mercury in the 
 tube will indicate the perfectness of the vacuum in the condenser, by ex- 
 hibiting the height at which it is supported by the pressure of the atmosphere. 
 If the vacuum is perfect, the mercury will stand from 28 to 31 inches. 
 
 The only difference between the working of this engine and 
 those already described is, that the pipe HH, instead of being 
 an injection pipe for the admission of cold water to the cylin- 
 der, merely leads off the steam to the condenser B, therefore, 
 when condensation is to be effected, the cock h is opened to 
 admit the steam from the cylinder into B, there to become 
 condensed, whilst the continued action of the pump C main- 
 tains a vacuum in B, by drawing off the condensed water and 
 the air. The cold-water pump F keeps up an abundant 
 supply in the cistern E E, and the superplus is discharged at 
 W ; thus maintaining a depression of temperature sufficient 
 to procure condensation in B. 
 
 Such was the importance of this alteration in the mode of 
 construction^ that one half the quantity of fuel consumed by 
 an engine of the former construction was saved. Still, how- 
 ever, the engine was not complete ; the piston was required to 
 have water kept upon its upper surface to keep it air-tight, and 
 as this, in the descent, cooled the cylinder considerably, it 
 was, as is evident from what has been already stated, when 
 speaking of the former mode of injecting cold water, pro- 
 ductive of a loss, to which Mr. Watt turned his serious 
 attention, and eventually succeeded in remedying the evil. 
 
 The next construction of the engine is what is now called 
 the single acting engine, and as the improvement con- 
 sisted merely in the c} liiider, a diagram of that will be sufficient 
 to make it clearly understood. Finding, as has been stated, 
 the disadvantages attending the open-ended cylinder, Mr, 
 Watt conceived the idea of closing the top of the cylinder, 
 and of causing tlie piston-rod to work through a close collar 
 stuffed with hemp and grease ; and instead of making use of 
 water to procure tlie piston working air-tight, of using oil or 
 fat as a substitute 5 and instead of causing it to descend by the 
 pressure of the atmosphere, of employing steam of an ex- 
 pansive force equal to that pressure. 
 
 In reference to fig. 175, A is the cylinder; B the piston; CC the stuffing- 
 bpx filled with hemp moistened with tallow, having its cap screwed firmly 
 
AND MACHINIST. 
 
 1 73 
 
 down by two screws, so as to form a steam-tight joint round the piston-rod. 
 The piston-rod being turned true and polished, is capable of working up 
 and down through the steam-tight joint. D is the steam pipe leading from 
 the boiler; K the eduction pipe leading to the condenser; H and I are two 
 valves upon the rod L, which passes through stuffing-boxes, or steam-tight 
 joints, at m n. While raising and lowering the rod L, the valves H and I 
 open or close their respective apertures D and K. ^ is a valve which affords, 
 when open, a communication between the top and bottom of the cylinder 
 through the pipe P E, and from thence through O, Its spindle, which is 
 hollow, works in a steam-tight collar at N, and has the rod L passing 
 through it, likewise steam-tight, in such a manner, that the rod L, with its 
 valves, may be moved independent of the valve g, or the valve g independ- 
 ent of the rod L. If the valves are placed as represented, I and H open, 
 and g shut, and the steam be permitted to come from the boiler through D, 
 it will pass through II, and enter the top of the cylinder at P, depressing the 
 piston B by its elastic force, whilst the lower part of the cylinder is open 
 through O and K to the condenser. When the piston is depressed to B^, 
 the rod L must be moved downwards, and the valves II and I closed, and 
 tlie valve g opened, that the steam, by its elastic force, may pass through 
 P E and the valve g, and act equally upon the lower as well as the upper 
 surface of the piston ; the piston, therefore, being in an unbiassed state, as 
 regards the pressure, will again be raised to its original situation by the 
 counterpoise weights acting at the other end of the beam, and the steam will 
 pass from above to below the piston. When it has arrived at that place, 
 the valves may be again put in their first position, as represented in the 
 drawing, when that at I, being open, affords a communication through O K 
 for the steam, which now occupies the cylinder below the piston, to pass to 
 the condenser, whilst fresh steam forces through D upon the upper surface 
 3f the piston tantamount to the pressure of the atmosphere, and produces an 
 effect fully equal to that obtained from an atmospheric engine. 
 
 In the engine just described, the beam was drawn down by 
 the pressure of the steam upon the top of the piston, and 
 when the steam had passed into the condenser, was raised by 
 counterpoise weights placed at its further end ; by which it 
 is manifest, that the action of an engine of this construction 
 must be somewhat irregular, for whilst the piston is descend- 
 ing the steam must act upon it to an amount capable of raising 
 the counterpoise weights, and of likewise doing the work put 
 upon it ; but when the piston is rising, the actual fall of the 
 counterpoise weights is the only amount of power which the 
 engine is supplying, and from which is to be deducted the 
 friction and weight of the piston. Such engines, therefore, 
 when a continuous and equable force is required, are not so 
 advantageous as those where the rising and depressing of the 
 piston are alike performed by the same means and the same 
 extent of force. This desirable end was accomplished by 
 Mr. Watt in the construction of the double-acting engine,* 
 which we shall next notice, in contradistinction to the one 
 that last claimed our attention, and which is now seldom used 
 for any other purpose than that of pumping water 
 
Tin: Ol’ERATIVF. MECHANiri 
 
 174 
 
 The double-acting engine is formed in such a manner that 
 whilst tlie steam is pressing on one side of the piston, the 
 cylinder on the other side is ahvays open to the condenser, 
 so that a vacuum exists on the opposite side to that on which 
 the pressure is exerted. This effect is produced by several 
 modes of distributing various pipes, or valves, or cocks. The 
 simplest in its construction is the four-way cock. 
 
 Fig. 176. A is the cylinder ; B the piston; C the pipe communicating 
 with the boiler; / m a communication with the condenser; I K and H g 
 communicate to the top and bottom of the cylinder ; C and D are two dif- 
 ferent passages through the plug of a cock, (the plug of the cock is shaded 
 for distinction,) capable of being turned by means of its handle m'. When 
 the cock is as now represented, the steam from C passes through D along 
 II, and g to beneath the piston, whilst there will be a direct communication 
 w'ith the condenser from above the piston through K I C* F M. When the 
 cock is turned in the position as represented in fig. 177, both these com- 
 munications will be inverted by the different dispositions of their openings. 
 The opening e in the plug will then afford a communication from the steam 
 pipe C to I, leading to the upper part of the cylinder; and the opening D 
 will permit a communication from H, leading from the lower part of the 
 cylinder to M, the eduction pipe, leading to the condenser; thus perfecting 
 by its motion the different changes of communication, so that the steam is 
 always made to act on the one side of the piston, whilst the vacuum is 
 effected on the other. The effect on the piston in ascending or descending 
 is equal, and the power is much more regular and convenient for application 
 to rotative motion. 
 
 Ill the single and the double engine the pressure of the 
 atmosphere is not used ; but the direct force of the steam 
 which, in the old engines, went to expel the atmosphere, and 
 then by its own condensation to leave a vacuum, is first re- 
 sorted to, and its condensation leaves a vacuum to assist the 
 action of the next supply. Consequently the single-acting 
 engine has not gained more power than the atmospheric 
 engine in proportion to the steam used, otherwise than by 
 what is saved through keeping the cylinder warm ; and the 
 double-acting engine is only a mode of using the steam in a 
 more continuous and unbroken manner, taking just twice the 
 (piantity of steam, and exerting twice the power of the single- 
 acting engine. 
 
 Other modes for attaining this change of communication, 
 so as to produce the double action, are adopted as circum- 
 stances may demand. The one last described, called the 
 four- way cock, was found not to answer in large engines, in- 
 asmuch as plugs of sufficient dimensions to afford steam- 
 way enough caused so much friction in their collars, that it 
 was an expenditure of considerable power to turn them ; the 
 method, therefore, most usually adopted in engines of large 
 
STEAM EPfG.l[NE 
 
 1 / 
 
 From 174 to 18Z * 
 
 6 
 
 j 
 
 iSi 
 
 n.zo 
 
 □ 
 
 D 
 
 182 * 
 
 O 
 
 jK II 
 
AND MACHINIST. 
 
 175 
 
 dimensions is, a system of valves, opened and shut at tlie 
 proper periods by levers. 
 
 The internal arrangement of such a system is shown at fig. 173, where C 
 is a pipe leading from the boiler for the conveyance of steam ; and D K a 
 pipe leading to L the condenser ; o p, m n, are two boxes, each divided in- 
 ternally into three compartments, in which are the valves efgh, capable 
 of opening upwards. From the centre compartment in each of the boxes 
 above and below there is a communication, at a and h, with the top and 
 bottom of the cylinder. The steam is conveyed along the pipe C into the 
 upper chamber of the upper box, and by means of the pipe i passes through 
 it and proceeds to the upper chamber of the lower box, and the pipe K D 
 affords a communication from each of the lower chambers to the con- 
 denser L. 
 
 If the valve h be opened, there will be a communication from the lower 
 part of the cylinder through the aperture 6 and pipe K into the condenser 
 L; and if, at the same instant, the valve e be opened, the steam will be ad- 
 mitted through C into the centre chamber of the upper box, and through 
 the aperture a into the upper part of the cylinder ; consequently the steam 
 will be admitted to the upper part ot the cylinder while the lower part has 
 communication with the condenser, and the piston be forced downwards. 
 If these valves be closed, and the valves g f opened, the steam will have 
 access through C h the valve and aperture b, to the lower part of the 
 cylinder, whilst there will be a communication from the top of the cylinder 
 through the aperture a, the valve f, and the pipe K D, to the condenser, so 
 that the piston will then be forced upwards. 
 
 This mode of effecting the changes of communication, 
 though by no means so simple as that of the four-way 
 cock, has an advantage over it that gives it a decided 
 preference. For as the movements of the valves are inde- 
 pendent of each other, the shutting off of the steam, and of 
 the communication with the condenser, can, if desired, be 
 effected at different periods, so that the steam may be allowed 
 to act upon the piston only during one half of the stroke, 
 which was discovered by Mr. Watt to effect a saving in 
 steam. Besides this advantage, which can, if required, be 
 effected in other engines by simple contrivances, the valve 
 geer is superior from its lightness, when compared to 
 slides or cocks, adapted to large engines. 
 
 In small engines, these advantages, not being of so much 
 importance, are more than counterbalanced by the simplicity 
 obtained by other modes. 
 
 The first that we shall notice was invented by Mr. Murray, of Leeds, and 
 is represented in fig. 179, where a section of this apparatus, termed the 
 slide valve, is shown. A is the steam pipe from the boiler ; B B B R a 
 close chamber, in which the interior chamber, C C, is capable of sliding 
 upwards and downwards by means of a rod, D D, which passes through a 
 steam-tight box at E. G G is a passage from the chamber B B B B to the 
 upper part of the cylinder ; HH to the lower part of the cylinder ; and 1 1 
 to the condenser. Now when the chamber C C is placed as is represented, 
 it is plain, that the steam has access to the top of the cylinder, and that a 
 
l/fi 
 
 THK OPERATIVE MBCIIAXIC 
 
 commun:c:itioii exists l)y II II aiul 1 I to tlie condenser. By moving C C 
 up wards, tlic communication would be reversed, tliat is, G(t from tlie top of 
 the cylinder would communicate by I I to the condenser, and li H admit 
 steam" into the lower part of the cylinder. By the movement of CC up- 
 wards and downwards, the alternating etfect is produced. 
 
 Messrs. Boulton and Watt introduced another very neat and 
 useful inode of distributing the steam in small engines, deno- 
 minated D valves, on account of the shape they present when 
 seen in atop view. 
 
 Fig. 130. A Band C D represent the two D valves capable of moving 
 upwards and downwards by means of the spindle E. Their faces at A and 
 C are made to fit steam-tight upon the inside of the box, and the back part 
 at B and D, as shown at D’, is semicircular, to admit of its being packed with 
 hemp in the same manner as the piston. G and II are communications to 
 tlie top and bottom of the cylinder ; I is the steam way in the boiler, which, 
 in some engines, comes from the jacket of the cylinder; and K is the educ- 
 tion pipe, which carries the steam to the condenser. 
 
 Now^ if the rod E be moved upwards until the lower surface of A B is above 
 the aperture II, the lower surface of C D will be above the aperture G, 
 consequently the steam from I will pass into the cylinder at H, and the steam 
 from the cylinder will pass through G and N K into the condenser. Again, 
 if the upper surface, A B, be below H, C D will be below G, and the steam 
 will pass through the aperture O, down a pipe behind M K, through P, 
 and, by means of G, will have access to the bottom of the cylinder, whilst a 
 communication will be effected by M K and through H, from the top of tlie 
 cylinder with the condenser. The rod E passes through steam-tight joints,^ 
 at top and bottom, into boxes. 
 
 Fig. 181 represents another manner of forming valves upon this principle, 
 in which a flat surface is introduced at the back, and the packing is effected 
 by having the faces, backs, and sides of the valves made of brass, and 
 fitted to plates of the same material, which can be screwed against the 
 valves as they w'ear. The slides or moving parts are shadowed. The ■po- 
 sition in w'hich they now are will admit the steam to pass from I through 
 II, and the condensation to be effected by passing from G through N to K ; 
 but if the slides be moved downwards until the aperture C is opposite G, 
 the upper slide wdll be below H, and the steam will pass through P into 
 tlio cylinder by means of G, and exhaustion will take place from II through 
 I\I to K, 
 
 Fig. 182 is a combination of what are called concentric valves. Their 
 distribution is exactly similar to those already explained. The spindles CC 
 of the lower valves, in both the top and bottom boxes, pass through the 
 spindles of the upper valves, which are pipes. Tliis mode of constructing 
 the valves was invented by Mr. Murray. They are capable of being moved 
 in many ways ; but the one most generally adopted is represented in the 
 figure, where the rods d e, attached to the cross-levers that move on the 
 centres G G G G, act upon the valves. Thus the rod c, by moving down- 
 wards, will raise the solid or the lower spindle valve of the lower box, which 
 opens to the condenser, and the hollow spindle the upper valve of the upper 
 box, which admits steam to the top of the cylinder, while the rod d acts 
 upon the other two, and changes the course of the steam and exhaustion, as 
 before shown. 
 
 Conceiving that we have sufficiently explained the several 
 modes of guiding the immediate power of steam, we shall in 
 
AND MACHINIST. 177 
 
 the next place proceed to examine into the construction of 
 the piston. 
 
 A section of the piston most commonly used in condensing engines is ex- 
 hibited in fig. 183. The lower face of the piston is fixed to the rod rfrf, and 
 the upper face is capable of being raised up upon the rod d. Hemp 
 moistened with tallow, called packing, is introduced round the interstice at 
 C E, which, when the upper plate D D is screwed down by the screw at 
 E E, is forced outwards against the sides of the cylinder, so as to render it 
 perfectly steam-tight. As it wears by the friction against the cylinder 
 more must be forced out by tightening the screws; and when entirely worn, 
 the plate d d must be raised and the piston fresh packed. 
 
 This construction of the piston answers perfectly for condensing engines ; 
 but in high-pressure engines the hemp is destroyed so rapidly by the heat 
 and friction, that pistons formed entirely of metal have been introduced with 
 advantage. 
 
 Tlie top view of one kind of metallic piston is represented at fig. 184. 
 A A A A is a ring of brass divided into four equal disconnected portions, 
 resting upon the plate B B, which is affixed to the piston-rod d d, as seen in 
 fig. 185 ; the portions of the ring are forced outwards against the sides of 
 the cylinder by springs of any convenient form pressing from the piston-rod 
 D. A^, in fig. 185, represents a side view of a similar ring, similarly 
 divided. Its portions are placed upon the ring last described, so that the 
 divisions fall upon the centres of the other four pieces, and are forced 
 against the sides of the cylinder in like manner by springs, and the plate C C 
 is placed over the whole. The upper and lower sides of the plate and rings 
 are all carefully ground, so as to fit steam-tight. This form of piston, 
 though it has, in some cases, been used for a considerable time with advan- 
 tage, is, upon the whole, defective, as the rings near the interstices between 
 the segments, must open and allow the steam to gain access to the interior 
 where the springs lie, and from thence, through similar interstices, to the 
 other side of the piston. 
 
 A metallic piston of a better construction is shown at fig. 1 86, consisting 
 of six pieces of brass of the forms represented in the figure, by ABC D E F. 
 ABC are circular, and are made to fit the inside of the cylinder, 
 against which they are forced by the wedge pieces D E F, which have 
 springs behind them. When ABC wear so as to divide at the angles, the 
 wedge pieces protrude themselves against the cylinder, keeping the space 
 always filled. These pistons have, in some cases, been used for many years 
 without requiring alteration. 
 
 Having now duly considered the construction of the cylin- 
 der, or seat of motion, and the means of distributing the 
 operative power so as to produce a reverting rectilinear 
 action, we shall next proceed to' exhibit the manner in which 
 this action is transferred, so as to maintain its continuance. 
 
 The movement of a four-way cock may be accomplished by a plug-tree, 
 which is a perpendicular rod attached to the beam of the engine as repre- 
 sented in fig. 187. OP are two studs or pins placed at such a distance 
 from each other, that the upper one, O, shall force the handle N to the 
 situation of W, just as the piston shall have reached the lower part of the 
 cylinder, and the pin P is so placed that it shall carry the handle to its 
 original situation at the time when the piston is again to change its direc- 
 
 N 
 
IJS the operative mechanic 
 
 tion. But the plug-tree is now seldom used in engines that have a rotative 
 motion; and where there is no rotative motion, the engines are mostly 
 single action, and arc applied only to the purpose of pumping, in which 
 the power is only required to be exerted whilst the piston is descending. 
 
 In engines for turning mill-work, where a rotatory motion 
 exists, the action is given to the spindle valves, sliding 
 valves, or whatever apparatus is used for the same object, by 
 means of a rod working from the axis of the fly-wheel by an 
 eccentric motion. 
 
 In fig. 188, the small circle is supposed to be a section of the fly-wheel 
 sliaft, and B a circular piece on the shaft, round which the clips, or semi- 
 circular pieces, CC, are fastened, so that B can turn on them, therefore 
 when the revolving of the shaft A carries B to the situation of the dotted 
 circle B*, it is plain that it will have forced the rod in an horizontal direc- 
 tion the distance from the centre of A to Bh and when in the course of its 
 revolution it shall liave brought B to the situation B‘^, it will have moved it 
 a similar distance in a contrary direction, consequently the total amount of 
 the horizontal motion thus communicated to the rod DEE will be the amount 
 of tlie distance from B^ to B^. The horizontal is converted into a perpen- 
 dicular motion by the crank h g i raising and lowering the rod K, upon 
 wliich the slide box or D valves is fixed. 
 
 Tlie method for moving the rods of concentric valves is represented in fig. 
 182*. E is the rod from the eccentric motion, which, by its backward and 
 forward motion, moves the ends //of a T piece, fastened on the centre G, 
 and causes them to move alternately upwards and downwards, opening 
 and shutting each pair of valves as before described. 
 
 Fig. 190 represents a mode, applicable to large engines, of moving either 
 U valves or slides from an eccentric. A B is an iron plate, capable of 
 vibrating upon its centre H ; F is a rod from the eccentric, moving the weight 
 C upon a roller over the surface of A B. The latch pieces D move upon 
 t\\ o pins, and are prevented falling forwards by the stops M N. The rod 
 of the valves, shown at <?, is attached by the lever P H to the shaft from the 
 centre H. Tire two stops, I and G, support A B in the two positions shown, 
 the one in the view, the other by the dotted lines. When the rod F moves, 
 it carries C towards A by the eccentric motion, and C, acting on the same, 
 raises the latch D, and permits the end A of A B to fall, whilst the end B, 
 in rising, latches itself at Dh shown in the dotted representation of A B. By 
 this motion II P, on the same axis H, is moved downwards, carrying 
 with it the rod E attached to the slides ; and the motion of C, instantly 
 changing towards F, acts upon the other latch and places the slides in 
 their former position. 
 
 As the beam of all engines vibrates upon a centre, of 
 course it performs portions of a circle with each of its extremi- 
 ties ; and as the rod of the piston is required to move up and 
 down in a straight line, it cannot be attached to the end of 
 the beam. In single engines of the old construction, where 
 the action was a pull at both ends of the beam, (at the one 
 end by the weight of the pump-rod, and at the other by the 
 down stroke of the piston,) a chain was affixed to the upper 
 
AND MACHINIST. 
 
 179 
 
 part of each of the curved ends of the beam, and to the pump 
 and piston rods, as represented in fig. IJO, which answered 
 the required purpose ; but in double-acting engines, where 
 the piston-rod forces upwards as well as pulls, some other 
 mode of converting the action is required. The most perfect 
 yet introduced is the parallel motion, the principle of which 
 may be comprehended by referring to fig. 191. 
 
 Suppose A B to represent one end of a beam, vibrating on its centre at 
 A, the other end B will perform the arc C Ch and carry whatever is 
 attached to it in the direction of that arc ; then suppose another rod, G H, 
 of equal length to A B, vibrating on its centre G, the point in the connect- 
 ing piece, L II, will, by the vibrations of A B and H G, move upwards and 
 downwards in a perpendicular line. For so much as the curve from the 
 radius A B draws it towards A, so much will the curve of the radius II G 
 draw it towards G, and the movements, correcting each other, will cause I 
 to rise and fall in a perpendicular line. 
 
 A more simple mode, which answers very well in small engines, is repre- 
 sented in fig. 192. The sling piece attached to the end of the beam has a 
 pair of rollers, one on each side, which press on each side of the guiding 
 bars D D D D, and carry the piston, attached at C, in a perpendicular 
 line. 
 
 All steam-engines are proportioned to go at a settled 
 rate, and to make a certain number of strokes of the piston 
 per minute, which, reckoning the number of feet the piston 
 travels in its upward and downward motion in the cylinder, 
 has been by general agreement settled at 200 to 220 feet 
 per minute. 
 
 To obtain this regularity of action, it is manifest that a 
 regularity must be obtained in the amount of power that is to 
 produce the movement ; or, in other words, a regular amount 
 of elastic force must be exerted at each stroke of the piston. 
 This is somewhat difficult to accomplish, and depends much 
 upon keeping the fire, which generates the steam, of a uni- 
 form heat ; consequently the care of the fire should only be 
 intrusted to one who is well skilled in his business. There 
 are, however, contrivances, called governors, which greatly 
 assist in maintaining a regular action, and where very great 
 nicety is not required, they produce it to a sufficient extent. 
 
 The governor (which we have already described under the 
 article 0?z the Equalization of Motion” in Mill-geering) 
 acts upon the principle of centrifugal force, and is applicable 
 only to engines that have a rotative motion. 
 
 The mode of applying the governor is by connecting it by 
 means of levers to a throttle valve, shown in fig, 193. A B 
 represents a section of the pipe that conveys the steam from 
 the boiler, having a small circular fan of iron, capable of being 
 
 N 2 
 
THE OPERATIVE MECHANIC 
 
 180 
 
 turned so as to be parallel with the line of the pipe, or 
 of lying across it in such a manner as to stop the com- 
 munication. 
 
 The governor is placed at any convenient part of the engine, 
 upon an upright spindle, and is driven either by a band or by 
 bevil-wheels, from the fly-wheel shaft. VVhen the fly-wheel 
 increases or decreases in velocity it transmits the same to the 
 governor, and causes the balls to fly from, or approach nearer 
 to, each other ; and the lever affixed to the collar of the 
 governor turns the handle C of the throttle valve, which 
 regulates the supply of steam, and produces regular motion. 
 
 In single-acting engines, which do not create rotative 
 motion, this sort of governor cannnot be applied, nor is it de- 
 cidedly adapted to the sort of regulation they want ; for as 
 tliey act only one way, and the steam being entirely shut olf at 
 the end of every stroke, it is a regulation of the amount of 
 power to be exerted at every interval which is sought, rather 
 than a continuous equable supply of steam. 
 
 This sort is most wanted in engines that supply towns with 
 water, as when the dififerent districts are being supplied, the 
 diversity of their magnitude and situation causes a consider- 
 able variation in the burden thrown upon the engine. In 
 engines used for this purpose there are two pieces of wood, 
 called spring-beams, placed across each end of the beam, 
 which, when the burden is lightened, and the engine makes 
 too long a stroke, strike, as they descend, the upper floor of 
 the engine-house and ring a bell, to warn the attendant that 
 steam must be shut off earlier, or that the upper tapit of the 
 plug-tree must be moved downwards. In engines of recent 
 construction, the spring-beams are made to strike a lever, 
 w’liich either shuts oft’ the steam entirely, or opens a cock that 
 admits it into the cylinder : in either case the movement of 
 the engine ceases. 
 
 The regulation of the plug-tree tapit is obtained by intro- 
 ducing a pipe from the water in the air-vessel to a small cylin- 
 der, having a working piston. The water from the air-vessel 
 forces against the under side of the piston and raises it and its 
 rod, and by that motion tlie tapit of the plug-tree is raised or 
 lowered as is required. This mode, from error in construc- 
 tion, or otherwise, has mostly proved inefficient when the 
 burden of the engine is liable to great and rapid fluctua- 
 tions. 
 
 Such is the general construction of engines now in use; 
 but there are many ingenious contrivances in boilers which 
 require special notice. 
 
AND MACHINIST. 
 
 181 
 
 Fig. 1 94 represents a boiler fitted up with all the appendages now 
 generally applied, and set in a furnace of a proper construction. Part of 
 the furnace is shown in a sectional view. B B B B the boiler, the operation 
 of which has been described. C, the steam-gauge, represented at large in 
 fig. 195. Its object is to ascertain the pressure acting in the boiler. It is 
 formed of a bent iron tube, at one end A communicating with the boiler, 
 and at the other end B open to the atmosphere. The tube is filled up to 
 C and D with mercury, and has a thin piece of stick, E, placed in the leg 
 
 B, which floats perpendicularly in the mercury at D. To the leg B is 
 appended a flat piece of brass, divided into inches, and numbered upwards, 
 to form a scale. The stick is made of such length that the top of it shall be 
 even with the first mark on the scale. 
 
 If the steam in the boiler presses against the mercury at 
 
 C, and raises the surface, D, one inch, (which will be indicated 
 by the end of the stick rising to 1 upon the scale,) it proves 
 that there is one half pound pressing per square inch against 
 the internal surface of the boiler, tending to burst itj for if 
 the section of the bore of the pipe was just one superficial 
 inch the pressure would be supporting one cubic inch of 
 mercury, which will be found to weigh near half a 
 pound; therefore for every two inches rise, one pound 
 pressure may be reckoned, and as condensing engines 
 seldom work with more than three or four pounds pressure 
 upon the inch, the scale need not be longer than .eight or 
 nine inches. 
 
 C* is a strong iron plate, covering a circular or oval hole of about 18 
 inches diameter, to admit a man into the boiler with a view to clean or 
 examine it. 
 
 D is the steam pipe, containing the throttle valve E, to which the rod 
 from the governor is connected. F F are gauge cocks. I I is a feed pipe 
 which passes into the boiler and reaches very near to the bottom. II H H II 
 the cistern, on the top of the feed pipe ; i i is a float, formed of stone, and 
 balanced so as to remain always on the surface of the water in the boiler. 
 By the raising and hilling of the water the float acts upon the lever K 
 by the wire P, which passes through a steam-tight joint at I^, and as the 
 water sinks, draws down the end K, which raises K^, and the valve M 
 attached to it. By this contrivance when the boiler requires a fresh supply 
 of water the valve M opens and supplies it from the cistern H H H II. 
 
 The feed pipe II is made to contain a column of water equal to the 
 amount of pressure exerted by the steam in the boiler, which we have 
 already stated should not exceed the supporting of eight inches of mercury. 
 As one inch of mercury being equal in weight to about 13§ inches of water, 
 the pipe should be about nine feet high from the surface of the water when 
 the boiler is supplied ; and the water in the feed pipe should stand about 
 three feet when the pressure is six inches of mercury, or three pounds to the 
 square inch of surface. 
 
 The feed pipe contains likewise an iron bucket weight O, hung by a chain 
 that passes over two pullies, P P ; to the other end of the chain is attached 
 a sheet of iron called a damper. When the steam in the boiler is urged to 
 too great an extent, it forces the w^er in the feed pipe upwards, and raises 
 
182 the operative mechanic 
 
 the iron bucket weight O, which lowers the damper into the flue of the 
 chimney, and checks the force of the fire. ^ , 
 
 S is a safety valve, loaded with a determinate weight, and of such a 
 dimension in the bore, as will relieve the boiler of its pressure should it 
 arrive beyond a certain temperature. It is enclosed in ackse, to prevent the 
 engine tender having access to it, as some engine tenders have been known 
 to load the safety valves, to save themselves the trouble of attending to the 
 fire with that diligence which is necessary, and by which they have endan- 
 gered theii own lives as well as the lives of others. 
 
 A pipe proceeds from this case to the chimney, to carry whatever steam 
 may escape into the flue of the chimney. 
 
 There is very frequently another safety valve, which is open to the view 
 of the engine tender, to indicate when the fire is too high. 
 
 T T is a flue formed of sheet iron, and passing lengthwise through the 
 centre of the boiler so near to the bottom that it is always covered with water. 
 
 The flame and smoke from the fire at n n passes first under the boiler, 
 and then immediately returns back through this flue, then dividing itself 
 passes through flues which lead it on both sides the boiler to the chimney. 
 
 ^ V is a cock for the purpose of emptying the boiler when required to be 
 cleaned or repaired. 
 
 Such is the construction and general arrangement of the 
 parts of Messrs. Boulton and Watt’s engines both single and 
 reciprocating. We shall now proceed in the examination of 
 some other forms of engines which likewise condense their 
 steam. 
 
 Mr. Hornblower, conceiving he could obtain greater power 
 from the complicated force of steam acting in two cylinders, 
 obtained a patent, in 1781, for that object. His own account, 
 taken from the specification, we here transcribe. 
 
 First,” says Mr. H., I use two vessels, in which the 
 steam is to act, and which in other engines are called 
 cylinders. Secondly, I employ the steam after it has acted 
 in the first vessel to operate a second time in the other, by 
 permitting it to expand itself, which I do by connecting the 
 vessels together, and forming proper channels and apertures, 
 whereby the steam shall occasionally go in and out of the said 
 vessels. Thirdly, I condense the steam, by causing it to 
 pass in contact with metalline surfaces, while water is applied 
 to the opposite side. Fourthly, to discharge the engine of 
 the water used to condense the steam, I suspend a column 
 of water in a tube or vessel constructed for that purpose, on 
 the principles of the barometer, the upper end having open 
 communication with the steam vessels, and the lower end 
 being immersed in a vessel of water. Fifthly, to discharge 
 the air which enters the steam vessels with the condensing 
 water or otherwise, I introduce it into a separate vessel, 
 whence it is protruded by the admission of steam. Sixthly, 
 that the condensed vapour shall not remain in the steam 
 
AND MACHINIST. 
 
 183 
 
 vessel in which the steam is condensed, I collect it into 
 another vessel, which has open communication with the steam 
 vessels and the water in the mine, reservoir, or river. 
 
 Lastly, in cases where the atmosphere is to be employed 
 to act on the piston, I use a piston, so constructed as to 
 admit steam round its periphery, and in contact with the 
 sides of the steam vessel, thereby to prevent the external air 
 from passing in between the piston and the sides of the 
 steam vessel."’ 
 
 The following is a description of this engine by the inventor : “ Let A and 
 B, fig. 196, represent two cylinders, of which A is the largest; a piston 
 moves in each, having their rods, C and D, moving through collars at E 
 and F. These cylinders may be supplied with steam from the boiler by 
 means of a square pipe G, which has a flanch to connect it with the rest of 
 the steam pipe. This square part is represented as branching off to both 
 cylinders : c and d are two cocks, which have handles and tumblers as 
 usual, worked by the plug-beam W. On the fore side of the cylinders 
 (that is, the side next the eye) is represented another communicating pipe, 
 whose section is also square, or rectangular, having also two cocks, a, h. 
 The pipe Y, immediately under the cock 6, establishes a communication 
 between the upper and lower parts of the small cylinder B, by opening the 
 cock b. There is a similar pipe on the other side of the cylinder A, imme- 
 diately under the cock d. ■ 
 
 “ When the cocks c and a are open, and the cocks b and d are shut, the 
 steam from the boiler has free admission into the upper part of the small 
 cylinder B; and the steam from the lower part of B has free admission 
 into the upper part of the great cylinder A ; but the upper part of each 
 cylinder has no communication with its lower part. 
 
 “ From the bottom of the great cylinder proceeds the eduction pipe K, 
 having a valve at its opening into the cylinder; it then bends downward, 
 and is connected with the conical condenser L. The condenser is fixed on 
 a hollow box M, on which stand the pumps N and O, for extracting the air 
 and water, which last runs along the trough T, into a cistern U, from which 
 it is raised by the pump V, for recruiting the boiler, being already nearly 
 boiling hot. Immediately under the condenser there is a spigot valve at 
 S, over which is a small jet pipe, reaching to the bend of the eduction pipe 
 K. The whole of the condensing apparatus is contained in a cistern, R, 
 of cold water ; a small pipe, P, comes from the side of the condenser, and 
 terminates on the bottom of the trough T, and is there covered with a valve, 
 Q, which is kept tight by the water that is always running over it. 
 
 “ Lastly , the pump-rods, H, cause the outer end of the beam to preponderate, 
 so that the quiescent position of the beam is that represented in the figure, 
 the pistons being at the top of the cylinders. 
 
 “ Suppose all the cocks open, and steam coming in copiously from the 
 boiler, and no condensation going on in L, the steam must drive out all 
 the air, and at last follow it through the valve Q. Now shut the cocks b 
 and d, and open the valve S of the condenser; the condensation will 
 immediately commence, and draw off the steam from the lower part of the 
 great cylinder. There is now no pressure on the under side of the piston 
 of the great cylinder A, and it immediately descends. The communication, 
 Y, between the lower part of the small cylinder, B, and the upper part of 
 the great cylinder. A, being open, the steam will go from the lower part of 
 B into the space left by the descent of the piston of A. It must, therefore, 
 
THE OPERATIVE MECHANIC 
 
 184 
 
 expand, and its elasticity must diminish, and will no longer balance the 
 pressure of the steam coming from the boiler, and pressing above the piston 
 
 of B. 1 j 1 j -11 • 
 
 “ Tins piston, therefore, if not withheld by the beam, would descend till it 
 
 came in equilibuo, from having steam of equal density above and below it. 
 But it cannot descend so fast ; for the cylinder A is larger than B, and the 
 arch of the beam, at which the great piston is suspended, is no longer than 
 the arm which supports the piston of B ; therefore, when the piston of B 
 has descended as far as the beam will permit it, the steam between the two 
 pistons occupies a larger space than it did when both pistons were at the 
 top of their cylinders, and its density diminishes as its bulk increases. The 
 steam beneath the small piston is, therefore, not a balance for the steam on 
 the upper side of the same, and the piston B will act to depress the beam 
 with all the difference of these pressures. 
 
 “The slio-htest view of the subject must show the reader, that as the pistons 
 descend, the steam that is between them will grow continually rarer, and less 
 elastic, and that both pistons will draw the beam downwards. Suppose 
 now, that each one had reached the bottom of its cylinder, shut the cock a, 
 and ’the eduction valve at the bottom of A, and open the cocks b and d. 
 The communication being now established between the upper and lower 
 part of each cylinder, their pistons will be pressed equally on the upper 
 and low’er surfaces; in this situation nothing, therefore, hinders the counter- 
 weight from raising the pistons to the top. 
 
 “ Suppose them arrived at the top : the cylinder B is at this time filled 
 with steam of the ordinary density, and the cylinder A with an equal 
 absolute quantity of steam, but expanded into a larger space. Shut the 
 cocks b and d, and open the cock a, and the eduction valve at the bottom of 
 A, the condensation will again operate, and cause the pistons to descend ; 
 and thus the operation may be repeated as long as steam is supplied ; and 
 once full of the cylinder B of ordinary steam, is expended during each 
 working stroke.” 
 
 The cocks of this engine are composed of two flat circular 
 plates, ground very true to each other, and one of them turns 
 round on a pin through their centres : each is pierced with 
 three sectorial apertures, exactly corresponding with each 
 other, and occupying a little less than one half of their surfaces. 
 By turning the movable plate so that the apertures coincide^ 
 a large passage is opened for the steam ; and by turning it so 
 that the solid part of the one covers the aperture of the 
 other, the cock is shut. Such regulators are now very com- 
 mon in the cast-iron stoves for warming rooms. Mr. Horn- 
 blower’s contrivance for making the collars for the piston 
 rods air-tight is thus : the collar is in fact two, placed at a 
 small distance from each other, and a small pipe, branching* 
 off from the steam pipe, communicates with the space between 
 the collars. This steam, being a little stronger than the 
 pressure of the atmosphere, effectually prevents the air from 
 penetrating through the upper collar; and though a little 
 steam should get through the lower collar into the cylinder 
 A, it can do no harm. The manner of making this stuffing- 
 
S T A M E N J( NE 
 
 From 106 to 'ZOO 
 
 ri.zz 
 
 197 
 
 
 r 
 
 ^«ele ^-StoeH^ 35Z Sty\xnd. 
 

AND MACHINIST 
 
 185 
 
 box is as follows : on the top of the cylinder is a box to 
 contain something soft, yet pretty close, to embrace the 
 piston-rod in its motion up and down; and this is usually a 
 sort of plaited rope of white yarn, nicely laid in, and rammed 
 down gently, occupying about a third of its depth ; upon that 
 is placed a sort of tripod, having a flat ring of brass for its 
 upper, and another for its lower part ; and these rings are in 
 breadth equal to the space between the piston-rod and the 
 side of the box. This compound ring being put on over the 
 end of the piston-rod, another quantity of this rope is to be 
 put upon it, and gently rammed as before ; then there is a 
 hollow space left between these two packings, and that space 
 is to be supplied with strong steam from the boiler. Thus is 
 the packing about the piston-rod kept in such a state as to 
 prevent the air from entering the cylinder when at any time 
 there may be a partial vacuum above the piston. 
 
 Mr. Hornblower’s description of this engine was followed 
 by a mathematical investigation of the principles of its action, 
 by the ingenious Professor Robison, which demonstrates that 
 it is the same thing in effect as Mr. Watt’s expansion engine; 
 but though this is true, there is a considerable difference in 
 the steps by which the effect is attained, which gives an 
 important advantage when it is reduced to practice. We 
 shall give an investigation in a more popular form, using only 
 common arithmetic. Mr. Hornblower assumed, that the 
 power or pressure of steam is inversely as the space into 
 which the steam is expanded ; this is the case with air, and 
 for the present w’e will grant it to be so with steam, and 
 reason from the same data as the ingenious inventor gives us. 
 
 To explain clearly what passes in the two cylinders, we 
 must deviate from the precise form of the engine, and divest 
 ourselves of one complication of ideas, by reducing both cylin- 
 ders to the same stroke ; therefore, suppose the engine to be 
 made like fig. 197, which represents the two cylinders placed 
 one upon the other, the lower one being double the capacity of 
 the upper one, and both pistons being attached to the same 
 rod, which may be applied to the end of the beam, so that the 
 descent of the pistons must draw up the load at the opposite 
 end of the beam. 
 
 Then, if we suppose the small piston to be ten inches in 
 diameter, the great piston must be 14,14 inches ; and to 
 avoid all difficulties of the ratio of the expansion, and the 
 pressure of steam, we will suppose the engine to be worked 
 by the pressure of atmospheric air instead of steam ; and for 
 the convenience of round numbers in our calculation we will 
 
THE OPERATIVE MECHANIC 
 
 18G 
 
 consider the pressure at only ten pounds per circular inch on 
 the surface of the piston. 
 
 The area of the small piston will be 100 circular inches, 
 and being assumed to move without friction, the pressure upon 
 it will be 10 X 100= 1000 pounds. The area of the great 
 piston is twice as much, or 200 circular inches, and the 
 pressure 2000 pounds. 
 
 Suppose both pistons to be at the top of their respective 
 cylinders ; let the atmospheric air be admitted to press freely 
 upon the upper surface of the small piston ; and suppose the 
 space between the two pistons filled with air of the same 
 density, while there is a perfect vacuum made in the lower part 
 of the great cylinder, beneath its piston. 
 
 Under these circumstances, the two pistons will begin to 
 descend with something less than 2000 pounds of pressure on 
 the great piston, by the air contained in the space between the 
 two pistons bearing on the 200 inches of surface with a weight 
 of 10 pounds per inch ; and beneath this piston there is no- 
 thing to counteract the pressure. At the same time, the small 
 piston, having air of equal density above and below it, is in 
 equilibrio. 
 
 This force would balance a load of 2000 pounds ; but sup- 
 pose we diminish the load to 1900 pounds, then the pistons | 
 will immediately begin to descend ; but they will soon stop, ’ 
 because the air between the two pistons must expand itself, to, 1 
 fill the increasing space occasioned by the equal descent of j 
 both pistons in the cylinders, one of which is twice the area 
 of the other ; and as the air becomes rarer, its pressure on the 
 great piston must diminish. Now as this same diminution , 
 occasions the small piston to have a power of descent, we 
 will first consider the pistons separately, and then conjointly, | 
 in their power of descent, with which they draw down the J 
 beam. 
 
AND MACHINIST, 
 
 187 
 
 Descending powef of the 
 srreat piston. 
 
 lbs. 
 
 At first, the power will be 2000 
 In consequence of the 
 pressure of 10 pounds per 
 circular inch upon its up- 
 per surface, and no pres- 
 sure beneath. 
 
 At one-fourth of the de- 
 scent, the power will 
 have diminished, by 
 regular decrements, to 1 600 
 Because the air be- i 
 
 tween the two pistons 
 must occupy three-fourths 
 of the small cylinder, and 
 one-fourth of the great 
 cylinder, which is a space 
 equal to one and one- 
 fourth of the original 
 space which it filled ; 
 therefore the spaces will 
 be. as 5 to 4; and if the 
 density of air is as the 
 inverse proportion of the 
 space which it occupies, 
 the pressure on the great 
 piston must be as 4 to 5, or 
 four-fifths of 2000 = 1000. 
 
 Descending power of the 
 small piston, 
 
 lbs. 
 
 A t first the power will be 0 
 Because the piston is in 
 equilibrio, having 1000 
 poundspressing upwards, 
 and 1000 pounds down- 
 wards. 
 
 At one-fourth, the power 
 
 will be 200 
 
 Because the equilibrium 
 does not continue, and at 
 one-fourth of the descent 
 the pressure beneath the 
 small piston is reduced by 
 the expansion of the air 
 between the two pistons 
 to four-fifths of 1000 = 800 
 pounds, while the pres- 
 sure above the piston con- 
 tinues to be 1000. The 
 power is, therefore, 1000 
 - 800 = 200. 
 
 Combined powers of 
 both pistons. 
 
 lbs. 
 
 At first . . . 2000 
 
 At one-fourth . 1800 
 
 At one-half of the de- 
 scent, the power will 
 have diminished to 
 Because at this position 
 the air between the pis- 
 tons occupies one-half of 
 the small cylinder and one- 
 half of the great one, 
 which is a space equal to 
 one and one-half of the 
 space it filled originally, 
 l^e spaces will therefore 
 be as 6 to 4, and the pres- 
 sure on the great piston as 
 4 to 6, or two-thirds of 
 2000 = 1333J. 
 
 At three-fourths of the 
 descent, the power will 
 be only .... 
 Because the air must 
 now occupy one-fourth of 
 the small cylinder, and 
 three-fourths of the large 
 cylinder, which is a space 
 equal to one and three- 
 fourths of the original 
 space. Thus the spaces 
 will be as 7 to 4, and the 
 pressure on the great pis- 
 ton four-seventlis of 2000 
 
 At one-half of the de- 
 scent, the power will 
 have increase.d to . 
 Because the pressure 
 beneath is diminished by 
 the increased rarity of the 
 air to two-thirds of 1000 = 
 662§, while the doumward' 
 pressure continues to be' 
 1000. The power is there- 
 fore 1000 - 662§ = 333|. 
 
 At three-fourths of the 
 descent, the power 
 
 will be 
 
 Because the pressure 
 beneath is reduced by the 
 rarity of the air to four- 
 sevenths of 1000 = 571|.; 
 therefore the power is 
 1000 - 571^ = 428^. 
 
 13331 
 
 1142f 
 
 At one -half 
 
 333 ^ 
 
 . 1666f 
 
 At three-fourths 1571^ 
 
 428 ^ 
 
 = 1142f . 
 
 At the bottom of the cy- 
 linder the power will be 1000 
 Because the air must 
 occupy the whole of the 
 large cylinder, a space 
 equal to twice the small 
 cylinder which it at first 
 filled. The pressure will 
 therefore be one-half of 
 
 2000 . 
 
 Sum of the powers ex- "I 
 erted by the great >7076 
 piston in its descent. J 
 
 At the bottom, the power 
 
 will be 
 
 Because the air beneath 
 the piston is reduced to 
 one-half of its pressure, or 
 500, w'hich, deducted from 
 1000, leaves 500. 
 
 Sum of the powers of ) 
 the small piston . / 
 
 500 
 
 1461 
 
 At the bottom. 1500 
 
 Sum of the "I 
 
 combined >8538 
 powers J 
 
THE OPERATIVE MECHANIC 
 
 188 
 
 Upon tlic action of this engine Dr. Rees, in his C 5 ^clop 8 edia, 
 presents us with the following remarks and comparative 
 statement between it-and Mr. Watt’s principle of expansion. 
 
 Now let us consider how Mr. Watt’s principle of expan- , 
 sion would operate in the same circumstance ; that is, in a 
 cylinder of 14,14 inches diameter; which is to be supplied 
 with air of 10 pounds pressure per circular inch, until it has 
 completed one- half of its descent, and leaving the remainder 
 of the descent to be accomplished by the expansion of the 
 air already contained in the upper half of the cylinder. 
 
 lbs 
 
 At the beginning, the power of descent will be 2000 
 
 At one-fourth, the power will still be 2000 
 
 At one-half, the power will be 2000 
 
 At three-fourths of the descent, the power will be diminished to . 1333J 
 
 Because the air must occupy one-fourth of the length of the 
 cylinder, in addition to that half of the cylinder which it occupied 
 before the expansion began; therefore the space is one and a half 
 times the former, or as 3 to 2, and the pressure will be two-thirds 
 of 2000. 
 
 At the bottom, the pressure will be 1000 
 
 Because the air is expanded to occupy twice the space it filled 
 
 before. 
 
 8333| 
 
 The sum total is veiy nearly the same as the former, but 
 both are greater than they should be, from the imperfect 
 manner in which we have been obliged to make our calcula- 
 tion, so as to express it in common arithmetic, without 
 liavlng recourse to fluxions, which is the only method of 
 treating quantities that are constantly increasing or decreasing 
 by any given law. 
 
 41ie source of the inaccuracy is easily explained : at first 
 wc set with the pressure at 2000 pounds in Mr. Hornblower’s 
 engine, and did not take into the account that it decreases 
 at all, until the piston has descended to one-fourth, but 
 reasoned as though it diminished all at once at that place ; 
 whereas it began to diminish from the very first starting. 
 Here then we have taken a small quantity too much. In the 
 same manner, our process takes no notice of the diminution 
 which happens between one-fourth and one-half of the 
 descent, or between the other points at which we have 
 chosen to examine it ; the result is, as if the diminution took 
 place suddenly at each of those points. The remedy for this 
 would have been to have taken the account at a greater 
 number of places, as it is by fluxions alone that we can take 
 an infinite number, so as to obtain a true result. Now in the 
 
AND MACHINIST. 
 
 189 
 
 second calculation of Mr. Watt’s expansion-engine, we have 
 taken a still less number of steps for the consideration of the 
 expansion, because, although there are four steps in the 
 process, two of them are before the expansion begins. 
 
 This is the reason of the apparent difference ; for in reality 
 there is none in the sum total of the varying pov/ers exerted 
 through the whole stroke, as will appear to any person who 
 will take the trouble to read Professor Robison’s investiga- 
 tion. But if we consider the difference of the manner in 
 which the whole power is expended during the stroke, we 
 shall see great reason to prefer Mr. Hornblower’s method, 
 from the much greater uniformity of the action ; it begins at 
 2000, and ends at 1500, whilst Mr. Watt’s begins at 2000, 
 and ends at 1000 ; hence the necessity of those ingenious 
 contrivances for equalizing the action in Mr. Watt’s patent of 
 1782. Mr. Hornblower’s is not uniform, but approaches 
 uniformity more nearly, so that he could have carried the 
 effect of the expansive principle much farther, in employing 
 stronger steam, than we believe he ever proposed to do. 
 
 We have been thus full upon this subject, because the 
 gaining more powder by the expansion of air or steam acting- 
 in double cylinders, has been a favourite idea with many, 
 and there are no less than five different patents for it, but 
 several of these have been upon mistaken notions; neither 
 Mr. Watt’s nor Mr. Hornblower’s can have any advantage 
 from shutting off the air, or from a double cylinder, when air 
 is used to press the piston ; nor could they derive any advan- 
 tage from the expansion of steam in their engines, if the 
 pressure of it was inversely as the space it occupies. 
 
 The advantage of the expansive principle arises wholly 
 from a peculiar property of steam, by which, when suffered 
 to expand itself to fill a greater space, it decreases in pressure 
 or elastic force by a certain law, which is not fully laid down ; 
 that is, the relation between its expansive force and the 
 space which it occupies is not clearly decided : but Mr. 
 Woolf has found that, by applying these properties in their 
 fullest extent to the double-cylinder engine, he can make 
 most important improvements in the effects which can be 
 obtained from any given quantity of fuel. Steam is a fluid 
 so different from air, as to have no one property in commou 
 with it, except elasticity. This elasticity is wholly derived 
 from the quantity of heat which it contains, and its force 
 increases and diminishes w ith the quantity of heat ; but by 
 what law it increases or diminishes we are uncertain, because 
 we have no measure of the actual quantity of heat which is 
 
190 THE OPERATIVE MECHANIC 
 
 contained in steam of any given elastic force. All we know 
 with certainty is what is stated in our table of expansion, 
 viz. that water, being converted into steam, and confined in 
 a close vessel, when heated until the thermometer indicates 
 a certain temperature, will have a certain pressure or elastic 
 force. But here we must observe, that the thermometer 
 indicates only the intensity of the heat, without affording a 
 direct measure of its quantity. When steam is suffered to 
 expand itself into any given space, the quantity of rarefied 
 water which will be found to be contained in any given bulk 
 of steam, in its expanded state, must be undoubtedly propor- 
 tioned to the quantity of water contained in the same bulk 
 of the steam, before the expansion took place, in the inverse 
 ratio of the space wdiich it originally occupied, and that space 
 which it fills v/hen expanded ; but we cannot say that this 
 is the case with heat ; and it is the quantity of heat alone 
 which determines the elastic force. 
 
 We believe that, in practice, Mr. Hornblower was not able 
 to obtain any greater effect from the application of the, 
 expansive action in two cylinders, than Mr. Watt did in one 
 cylinder. In 1791 — 2, he erected an engine in Cornwall 
 at Tin-Croft mine, of which the large cylinder was 27 inches 
 diameter, and worked with a stroke of eight feet long, and 
 the small cylinder 21 inches diameter, working with a six 
 feet stroke. The only account we have been able to obtain 
 of the performance of this engine, is from a pamphlet pub- 
 lished by Thomas Wilson, an agent of Messrs. Boulton and 
 Watt, professedly with a view to prevent the introduction of 
 Mr. Hornblower’ s engines into that country, in which he 
 makes it appear, that it raised only 14,222,120 pounds of 
 water one foot high with each bushel of coals. 
 
 In Mr. Hornblower’s own account of his engine, in Gre- 
 gory’s Mechanics^ he informs us, That an engine w^as 
 erected in the vicinity of Bath, some years since, on this 
 principle, and under very disadvantageous circumstances, 
 the engine had its cylinders 19 inches and 24 inches dia- 
 meter, with lengths of stroke in each suitable to the occasion: 
 viz. six feet and eight feet respectively. The condensing 
 apparatus was very bad, through a fear of infringement on 
 Mr. Watt’s patent, and the greatest degree of vacuum which 
 could be obtained, was no more than 27 inches of mercuiy. 
 The engine worked four lifts of pumps to the depths of 576 
 feet, 4500 pounds, 14 strokes in a minute, six feet each, with 
 a cylinder six feet long, and 19 inches diameter, with a 
 great deal of inertia and friction in the rods and buckets 5 
 
AND MACHINIST. 
 
 191 
 
 some of the latter of which were not more than 3| inches 
 diameter: and this it did^ under ail these disadvantageous 
 circumstances, with JO pounds of coal (light coal) per hour.’^ 
 
 To reduce this to the standard of one foot high, we must put the load 
 4500 pounds x 6 feet stroke = 27,000 pounds which the engine raised 
 one foot high at every stroke; 27,000 pounds x 14 strokes per minute = 
 378,000 pounds raised one foot high each minute ; 378,000 pounds x 60 
 = 22,680,000 pounds raised one foot high per hour, or with 70 pounds 
 of coals. As the coals are stated to be light, we will take them at only 
 84 pounds per bushel, instead of 88 pounds, as Mr. Srneaton did, and 
 say as 70 pounds : 22,680,800 pounds : : 84 pounds : 27,216,000 pounds of 
 water raised one foot high with a bushel of coals, wliich is a very good 
 performance, but not greater than Mr. Watt's. 
 
 In this engine, Mr. Hornblower says that two remarkable 
 circumstances jiresented themselves to show the advantages 
 of this application of the principle : the one was, that the 
 man who attended the engine would sometimes detach the 
 smaller cylinder from the beam, and work only with the large 
 one, and then the boiler would scarcely raise steam enough 
 to keep the engine going ; but no sooner was the small 
 cylinder-rod attached to the beam, than the engine resumed 
 its wonted activity, and the steam would blow up the 
 safety-valve. 
 
 The next circumstance is, that when the detent, which 
 kept the exhausting valve shut, happened to miss its action, 
 the piston would be checked, as it were, not being permitted 
 to rise through the whole of the returning stroke ; and it 
 would, as by an intuitive nature, come down again and 
 again, until the detent performed its office, which is a 
 practical argument for the power of the engine at the ter- 
 mination of its stroke. 
 
 Several engines have been constructed upon the princi- 
 ples of admitting a further expansion of the steam in a second 
 cylinder. The one, however, which has been most effectually 
 tried by comparison, is that which goes by the name of 
 Woolf’s engine. An account of which we transcribe, toge- 
 ther with other improvements in the minor parts, which 
 from their’ ingenuity are worthy of notice. 
 
 In 1804, Mr. Arthur Woolf had a patent for improvements 
 in steam-engines. The specification of his invention states, 
 that he has ascertained by actual experiment, and reduced to 
 practice, the following particulars respecting the expansibility 
 of steam. That, in practice, it is found that steam, acting 
 with the expansive force of four pounds pressure per square 
 inch against a safety-valve exposed to the atmosphere, is 
 capable of expanding itself to four limes the volume it then 
 
THE OPERATIVE MECHANIC 
 
 192 
 
 occupies, and still to be equal to the pressure of the atmo-* 
 sphere : that, in like manner, steam of the force of five pounds 
 the square inch, can expand itself to five times its volume j 
 and that masses or quantities of steam of the like expansive 
 force of six, seven, eight, nine, or ten pounds pressure per 
 square inch, can expand to six, seven, eight, nine, or ten 
 times their volume, and still be respectively equal to the 
 atmosphere, or capable of producing a sufficient action 
 against the piston of a steam-engine, to cause the same to 
 rise in the atmospheric engine of Newcomen with a counter- 
 poise, or to be carried into the vacuous part of the cylinder 
 of the improved engine, first brought into effect by Mr. Watt : 
 that this ratio is progressive, and nearly, if not entirely, uni- 
 form ; so that steam pressing with the expansive force of 20, 
 30, 40, or 50 pounds the square inch against a common 
 safety-valve, will expand itself to 20, 30, 40, or 50 times its 
 volume ; and that, generally, as to all the intermediate or 
 higher degrees of elastic force, the number of times which 
 steam of any temperature and force can expand itself, is nearly 
 the same as the number of pounds it is able to sustain on a 
 square inch exposed to the common atmospheric counter- 
 pressure ; provided always, that the space, place, or vessel, in 
 which it is allowed to expand itself, be kept at the same tem- 
 perature as that of the steam, before it is allowed room to 
 expand. 
 
 Respecting the different degrees of temperature required 
 to bring steam to, and maintain it at, different expansive 
 forces above the weight of the atmosphere, Mr. Woolf states, 
 that he has found by actual experiment, setting out from the 
 boiling point of water, or 212® of Fahrenheit, at which degree 
 steam of water is only equal to the pressure of the atmo- 
 sphere ; that, in order to give an increased elastic force equal 
 to five pounds on each square inch, the temperature must be 
 raised to about 227 i®, when it will have acquired a power to 
 expand itself to five times its volume, and still be equal to the 
 atmosphere, and capable of being applied as such in the work- 
 ing of steam-engines according to his invention. Various 
 other pressures, temperatures, and expansive forces of steam, 
 are shown in the following table. 
 
AND MACiHNIST, 
 
 193 
 
 Woolf ’s T Me of the relative pressures per square inch ; 
 the temperature and expansibility of steam at different 
 degrees of heat above the boiling point of water ^ begin- 
 ning with the temperature of steam of an elastic force 
 equal to Jive pounds per square inch, and extending to 
 steam able to sustain forty pounds on the square inch. 
 
 Pounds per 
 Square Inch. 
 
 Degrees of 
 Heat. 
 
 Steam of an 
 elastic force 
 predominat- 
 ing over the 
 pressure of 
 the atmo- 
 sphere upon 
 a safety-valve 
 
 5 
 
 
 227f^ 
 
 
 C 
 
 5 
 
 6 
 
 
 230J 
 
 
 6 
 
 7 
 
 
 2321 
 
 
 7 
 
 8 
 
 
 235J 
 
 and at these 
 
 8 
 
 9 
 
 requires to be 
 
 237^ 
 
 respective de- 
 
 9 
 
 J 10 
 
 maintained by 
 
 2394 
 
 grees of heat. 
 
 10 
 
 ^ L5 
 
 ^a temperature^ 
 
 2504 
 
 "steam can ex- 
 
 15 
 
 20 
 
 equal to about 
 
 2594 
 
 pand itself to 
 
 20 
 
 25 
 
 267 
 
 about 
 
 25 
 
 30 
 
 
 273 
 
 
 30 
 
 35 
 
 
 278 
 
 
 35 
 
 40 
 
 W J 
 
 
 282 
 
 
 40 
 
 times its vo- 
 lume, and con- 
 tinue equal in 
 elasticity to 
 the pressure 
 of the atmo- 
 sphere. 
 
 And so ill like manner, by small additions of temperature, 
 an expansive power may be given to steam to enable it to 
 expand to 50, 60, 70, 80, 90, 100, 200, 300, or more times 
 its volume, without any limitation but what is imposed by the 
 frangible nature of every material of which boilers and other 
 parts of steam-engines can be made. Prudence dictates that 
 the expansive force should never be carried to the utmost 
 which the materials can bear, but rather be kept considerably 
 within that limit. 
 
 Having thus explained the nature of his discovery, Mr. 
 Woolf proceeds to give a description of his improvements 
 grounded thereon. 
 
 If the engine is constructed originally with the intention of 
 adopting these improvements, it ought to have two steam 
 cylinders of different dimensions, and proportioned to each 
 other, according to the temperature or the expansive force 
 determined to be communicated to the steam made use of in 
 working the engine 5 for the smaller steam-vessel or cylinder 
 must be a guide for the larger. For example ; if steam of 
 forty pounds the square inch is fixed on, then the smaller 
 cylinder should be at least one-fortieth part the contents of 
 the larger one. Each cylinder should be furnished with a 
 piston, and the smaller cylinder should have a communica- 
 tion, both at its top and bottom, (top and bottom being here 
 employed merely as relative terms, for the cylinders may be 
 worked in a horizontal, or any other required position, as well as 
 vertical,) with the boiler which supplies the steam j and the 
 
 o 
 
m 
 
 THE OPERATIVE MECHANIC 
 
 communications, by means of cocks or valves of any construc- 
 tion adapted to the use, are to be alternately opened and shut 
 during the working of the engine. The top of the small cylin- 
 der should have a communication with the bottom of the larger 
 cylinder, and the bottom of the smaller one with the top of 
 the larger, with proper means to open and shut them alter- 
 nately by cocks, valves, or any other well-known contrivance. 
 And both the top and bottom of the larger cylinder should, 
 while the engine is at work, communicate alternately with a 
 condensing vessel, into which a jet of water is admitted to 
 hasten the condensation ; or the condensing vessel may be 
 cooled by any other means calculated to produce that effect. 
 
 This arrangement being made, when the engine is set to 
 work, steam of a high temperature is admitted from the 
 boiler to act by its elastic force on one side of the smaller 
 piston, while the steam which had last moved it has a com- 
 munication with the larger steam-vessel or cylinder, where it 
 follows the larger piston, now moving towards that end of its 
 cylinder which is open to the condensing vessel. Let both 
 pistons end their stroke at one time ; and let us now suppose 
 them both at the top of their respective cylinders, ready to 
 descend ; then the steam of forty pounds the square inch, 
 entering above the smaller piston, wdll carry it downwards; 
 while the steam below it, instead of being allowed to escape 
 into the atmosphere, or applied to any other purpose, will 
 pass into the larger cylinder above its piston, which will 
 make its downward stroke at the same time that the piston 
 of the smaller cylinder is doing the same thing ; and while 
 this goes on, the steam which last filled the larger cylinder in 
 the upward stroke of the engine will be passing into the con- 
 denser, to be condensed during the downward stroke. When 
 the pistons in the smaller and larger cylinder have thus been 
 made to descend to the bottom of their respective cylinders, 
 then the steam from the boiler is to be shut off from the top, 
 and admitted to the bottom of the smaller cylinder. The 
 communication between the bottom of the smaller and the top 
 of the larger cylinder is also to be cut off ; and the communi- 
 cation is to be opened between the top of the smaller and the 
 bottom of the larger cylinder. The communication between 
 the bottom of the larger cylinder and the condenser is to be 
 cut off, and the steam which, in the downward stroke of the 
 engine, filled the upper part of the larger cylinder, suffered 
 to flow off to the condenser. The engine will then make its 
 upward stroke from the pressure of the steam in the top of the 
 small cylinder acting beneath the piston of the great cylinder, 
 
AND MACHINIST, 
 
 195 
 
 and so on alternately, admitting the steam to the different 
 sides of the smaller piston, while the steam last admitted into 
 the smaller cylinder passes alternately to the different sides 
 of the larger piston in the larger cylinders : the top and bot- 
 tom of which are at the same time made to communicate 
 alternately with the condenser. 
 
 In an engine working in the manner just described, while 
 the steam is admitted on one side of the piston into the 
 smaller cylinder, the steam on the other side has room made 
 for its admission into the larger cylinder, on one side of its 
 piston, by the condensation taking place on the other side of 
 the large piston which is open to the condenser ; and that 
 waste of steam which takes place in engines worked only by 
 the expansive force of steam, from steam passing the piston, 
 is prevented ; for all steam that passes the piston in the 
 smaller cylinder is received into the larger. 
 
 In such an engine, where it may be more convenient for any 
 particular purpose, the arrangement may be altered, and 
 the top of the smaller made to communicate with the top of 
 the larger cylinder; in which case the only difference will be, 
 that when the piston in the smaller cylinder descends, that 
 in the larger will ascend, and vice versa; which, on some 
 occasions, may be more convenient than to have the two 
 pistons moving in the same direction. 
 
 This engine is exactly the same in its action as Mr. Horn- 
 blower’s, which we have before described. The novelty con- 
 sists in the application of steam of a high pressure thereto, and 
 in proportioning the capacities of the two cylinders to the 
 expansibility of the steam, according to his table. But Mr. 
 W. goes on to state, that effectual means must be used to 
 keep up the requisite temperature in all parts of the ap- 
 paratus into which the steam is admitted, and in which it is not 
 intended to be condensed ; and here it may be proper to state, 
 that instead of the usual means of accomplishing this, by en- 
 closing them in the boiler, or in a steam-case communicating 
 with the boiler, a separate fire may with advantage be made 
 under the steam-case containing the cylinders, which in that 
 event will become a second boiler, and must be furnished 
 with a safety-valve, to regulate the temperature. By means 
 of the last-mentioned arrangement, the steam from thes mailer 
 cylinder, or steam measurer, may be admitted into the larger 
 cylinder, when kept at a higher temperature than the steam 
 in the smaller cylinder, by which its power to expand itself 
 may be increased ; and, on the contrary, by keeping the 
 larger cylinder at a lower temperature than the smaller, its 
 
 o2 
 
TIIK OPLRATIVK MKChANIC 
 
 19G 
 
 expansibility will be lessened, which, on particular occasions, 
 and for particular purposes, may be desirable. In every case 
 care must be taken that the boiler, or case in which the cylin- 
 der is enclosed, the steam -pipes, and generally all the parts 
 exposed to the action of the expansive force of the steam, shall 
 have a strength proportioned to the high pressure to which 
 they are to be exposed. 
 
 It is not advisable that the proportion of the capacity of 
 the smaller cylinder, or steam-measurer, to the capacity of the 
 larger or working cylinder, should in any case be smaller than 
 the proportion of the expansion of the steam which is to be 
 used in it, as we have stated, yet, in the making of it larger, 
 considerable latitude may be allowed; for example, with 
 steam of forty pounds the square inch, a small cylinder, or 
 measurer, of one-twentieth, or even larger, instead of one of 
 fortieth the capacity of the larger or working cylinder, and so 
 with steam of any given strength. And in many cases, it may 
 be advisable that this should be the case, because of the 
 difficulty of preventing some waste of steam, or partial 
 condensation, which might lessen the rate of working, 
 if not allowed for in the size of the small cylinder or steam- 
 measurer. 
 
 In all cases when the engine is ready for working, whatever 
 may be the proportion that has been adopted, or intended to 
 be worked with, it should have its power tried by altering the 
 load on the valve that ascertains the force of the steam, in 
 order that the strength of steam best adapted for the engine 
 may be ascertained, for it may turn out to be advantageous, 
 that the steam should be employed in particular engines of 
 an elastic force somewhat over or under what was first 
 intended. 
 
 Mr. Woolf also states, that Mr. Watt’s engines may be 
 improved by the application of his discovery in making the 
 boiler, and the steam-case in which the working cylinder is 
 enclosed, much stronger than usual, and by altering the 
 structure and dimensions of the valves for admitting steam 
 from the boiler into the cylinder in such a manner that the 
 steam may be admitted very gradually by a progressive 
 enlargement , of the aperture, so as at first to wiredraw the 
 steam and afterwards to admit it more freely. The reason 
 this precaution is this, that steam of such elastic force as 
 Mr VVoolf proposes to employ, if admitted suddenly into the 
 cylinder, would strike the piston with a force as would en- 
 danger the safety and durability of the engine. The aperture 
 allowed for admitting steam into the cylinder, or cylinders. 
 
AND MACHINIST. 
 
 197 
 
 should be regulated by the following consideration. If the 
 intention is that the engine should work wholly, or almost 
 wholly, by condensation, the steam, in passing into the cylin- 
 der, should be forced to wiredraw itself only so much that the 
 piston may perform the whole, or a great part of the stroke, 
 by the time that the intended quantity of steam has been ad- 
 mitted into the cylinder. For example, when steam of forty 
 pounds on the square inch is used, such a quantity of it must 
 be allowed to enter as shall be equal to one-fortieth of the 
 capacity of the cylinder, and so in proportion when steam of 
 any other force is employed ; and when the requisite quantity 
 has been admitted, the steam is to be shut off till the proper 
 moment for admitting a fresh quantity. But if it is intended 
 that advantage shall also be taken of the elastic force of the 
 steam acting on one side of the piston, while condensation 
 goes on on the other side, then the steam must be admitted 
 more freely, but still with caution at first, for the reason 
 already mentioned. 
 
 This latter is the same thing as Mr. Watt’s expansion 
 engine ; but with the addition of gradually diminishing the 
 aperture of the steam-valve as the piston descends, instead of 
 stopping it altogether at a certain portion of the descent, by 
 which means the action of the engine is rendered more uni- 
 form. We think that, by regulating the descent of the valve 
 by an accurate movement, a very good effect may be pro- 
 duced in this manner, without the complication of two cylin- 
 ders or other parts ; the only objection is, that if at any time 
 the valve should be fully opened by accident, the pressure 
 might suddenly become so great, from the strong steam act- 
 ing upon the full surface of the piston, as to break the engine 
 to pieces. 
 
 In 1805, Mr. Woolf took out a second patent for further 
 improvements, in which he proposes, as before, to apply fire to 
 the cylinder itself, to heat the steam after it is thrown into 
 the working cylinder ; and this was to be done by a fire 
 being placed beneath the case containing the cylinder : the 
 space between the case and the cylinder was to be filled with 
 oil, wax, fusible metal, or mercury. He also proposes a 
 method of preventing the passage of any of the steam from 
 that side of the piston which is acted upon by the steam, to 
 the other side, which is open to the condenser. In those 
 steam-engines which act as double engines, he effects this by 
 employing, upon or about the piston, a column of mercury 
 or fluid metal, in an altitude equal to the pressure of the 
 btcam. The efficacy of this arrangement will, he says^ 
 
THE OPERATIVE MECHAKIC 
 
 1H8 
 
 appear obvious, from attending to what takes place in the 
 working such a piston. When the piston is ascending, 
 that is, when the steam is admitted below it, the space on 
 its upper side being open to the condenser, the steam, endea* 
 vouring to pass up by the side of the piston, is met, and 
 effectually prevented by the column of metal, equal or su- 
 perior to it in pressure, and during the down stroke, no 
 steam can possibly pass without first forcing all the metal 
 through. 
 
 Ill working what is called a single engine, a less consider- 
 able altitude of metal is required, because the steam always 
 acts on the upper side of the piston ; and in this case, oil, or 
 wax, or fat of animals, or similar substances, in sufficient 
 quantities, will answer the purpose. But care must be taken, 
 either in the double or single engine, when working with this 
 piston, that the outlet which conveys the steam to the con- 
 denser shall be so situated, and of such a size, that the steam 
 may pass freely, without forcing before it, or carrying with it, 
 any of the metal or other substance employed that may have 
 passed by the piston ; and at the same time providing another 
 exit for the metal, or other substance collected at the bottom 
 of the cylinder, to convey the same into a reservoir kept at a 
 proper heat, whence it is to be returned to the upper side of 
 the piston by a small pump, worked by the engine, or by 
 some other contrivance. In order that the fluid metal used 
 with the piston may not be oxydated^ some oil or other fluid 
 substance is always to be kept on its surface, to prevent its 
 coming in contact with the steam ; and to prevent the neces- 
 sity of employing a large quantity of fluid metal, although 
 the piston must be as thick as the depth of the column re- 
 ijiiired, the diameter need be only a little less than the steam- 
 vessel or working cylinder, excepting where the packing, or 
 other fitting, is necessary to be applied ; so that, in fact, 
 the column of fluid metal forms only a thin body round the 
 piston. 
 
 We have seen an engine of an eight-horse power of this 
 kind at work, with a fluid metal on the pistons : it effectually 
 prevented the leakage. But as it required to have the cylin- 
 ders twice as long as usual, in order to have sufficient room 
 for the long or thick pistons which it required, and as these 
 pistons must be of considerable weight, the method is not at 
 all applicable in practice ; and, indeed, the increase of the bulk 
 <)1 llie moving parts is such as to counterbalance the advan- 
 tage, which is confined to the saving of steam by leakage ; 
 foi I Ik ii’ictioii must be greater than in another engine, 
 
AND MACHINIST. 
 
 199 
 
 because the piston must be packed as tight as usual, to be able 
 to sustain a column of fluid metal, which must be more than 
 equal in pres>sure to that of the steam ; and when the steam 
 presses upon the piston, the pressure of the fluid metal to leak 
 by the piston must be double that of the steam : also the 
 friction of so great a surface of fluid metal pressing against 
 the inside of the cylinder is very great. 
 
 In 1810, Mr. Woolf had a third patent, the object of which 
 is to prevent the waste of steam from leakage by the piston. 
 For this purpose, he does not allow the steam to come to the 
 piston at all, but causes it to act in a different vessel, and 
 transmits the action thereof to the piston by oil or fluid metal : 
 thus, at the side of the cylinder, he places a separate vessel, 
 communicating with the lower part of the cylinder by a 
 large pipe or passage from the bottom of each ; then 
 steam, being admitted into this vessel, will press upon 
 the surface of the oil or fluid metal contained in it, and 
 force the same to pass out of that vessel into the cylinder, 
 where it will act beneath the piston to press the same up- 
 wards, a vacuum being at the same time made in the upper 
 part of the cylinder to give effect to the pressure. 
 
 The steam is then made to press upon the upper surface 
 of the piston, which is always covered with a quantity of the 
 fluid ; and at the same time a vacuum is made in the separate 
 vessel, so as to relieve the surface thereof from all pressure ; 
 in consequence the piston is made to descend. It is evident 
 that the piston must be packed so tight as to suffer none of the 
 fluid to pass by it ; but this is easy, in comparison with the 
 difficulty of making a packing sufficiently tight to resist the 
 passage of steam, particularly when it is so rare as the ex- 
 panded steam which Mr. Woolf sometimes uses in his 
 engine. The separate vessel of which we have spoken, is in 
 some cases to be the jacket or space which surrounds the 
 cylinder, which is then to be open at bottom. 
 
 This contrivance is ingenious, but we think the necessity 
 of an additional cylinder is an objection which will prevent 
 its adoption in large engines ; and for small engines the 
 advantages are not so great. 
 
 Since his first patent, Mr. Woolf has erected several small 
 engines, which performed well, and with an evident economy 
 of fuel. But these engines being employed to turn mills, of 
 which the operations do not afford so exact an estimate of the 
 power as the operation of pumping water, Mr. Woolfs 
 engines did not come to a direct and indisputable comparison 
 with those on Mr. Watt’s principle, until 1815, when tw’o 
 
IHK OPERATIVE MECHANIC 
 
 200 
 
 lari^e engines were set to work in Cornwall, at Wheal Vor 
 and Wheal Abraham mines, for pumping water ; and these 
 have since been regularly reported in Messrs. T. and J, 
 l^ean’s reports, and of which one of the objects was to ascer- 
 tain the comparative merit of the double and single cylinder 
 engines. 
 
 Tlie report for May, 1815, states the average performance of these two 
 engines at 49,980,882 lbs. lifted one foot high for each bushel of coals ; and 
 since that time they have done more than 50,000,000 lbs. 
 
 Tlie engine at Wheal Vor has a great cylinder of 53 inches diameter, and 
 nine-feet stroke; and the small cylinder is about one-fifth of the contents 
 of the great one. The engine works six pumps, which, at every stroke, raise 
 a loa.d of water of 37,982 lbs. weight 7^ feet high, which is the length of the 
 stroke in the pumps. This makes a pressure of 14,1 lbs. per square inch on 
 die surface of the great piston, and it makes 7,6 strokes per minute. With 
 respect to its consumption of coals, it raised, in March, 1816, 48,432,702lbs. 
 one foot high with each bushel; April, 1816, 44,000,000 lbs. ; May, 1816, 
 49,500,000 lbs. ; and in June, 1816, 43,000,000 lbs. 
 
 J’rom the same reports we learn, that the engine at Wheal Abraham mine 
 has a great cylinder of 45 inches diameter, working with a seven-feet stroke, 
 at the rate of 8,4 strokes per luiirute under a load of 24,050 lbs., which it 
 l aises seven feet at each stroke. Its performance during the above four 
 months was 50,000,000 lbs. ; 50,908,000 lbs. ; in May, 56,917,312 lbs., 
 which, we believe, is the greatest performance ever made by a steam-engine ; 
 and in June, 51,500,000 lbs. 
 
 We must observe, that the variation in the performance 
 of different steam-engines, which are constructed upon the 
 same principle, and working under the same advantages, is 
 the same as would be found in the produce of the labour of 
 so many different horses, or other animals, when compared 
 with their consumptive food; for the effects of different 
 steam-engines will vary as much from small differences 
 ill the proportions of their parts, as the strength of animals 
 from the vigour of their constitution ; and, again, there will 
 be as great differences in the performance of the same 
 engine, when in bad or good order, from all the parts 
 being tight and well oiled, so as to move with little friction, 
 as there is in the labour of an animal, from his being in good 
 or bad health, or excessively fatigued ; but in all cases, there 
 will be a maximum which cannot be exceeded, and an average 
 which we ought always expect to attain. 
 
 Fig. 198 is a sketch to show the arrangement of the valves and cylinders 
 of these two engines ; A is the large cylinder, and B the little cylinder, each 
 enclosed in its steam-case. Tlie steam is admitted from the boiler into the 
 steam-case of the large cylinder A, by a communication at C ; and there is 
 u communication between this steam-case and that of tlie small cylinder; 
 so that all the steam for the supply of the engine passes through both of the 
 sicam-cascs, wliich therefore become part of the communication between die 
 b'‘jler ait'l the litllc cylinder, into which the steam is first admitted, D 
 
AND MACHINIST 
 
 201 
 
 furtiishos a communication for carrying back to the boiler any water which 
 may be produced by condensation in the steam-case, before the engine is 
 heated to the proper temperature. E is the pipe from the steam-case to 
 supply the engine ; it has a regulating valve. F is the valve-box of the 
 small cylinder, the spindle of the one valve working through that of the 
 other ; and the passage for the steam from the case into the small cylinder is 
 situated between the two valves. G is the valve that opens the communi- 
 cation between the bottom of the small cylinder B and the top of the large 
 cylinder A, when the piston thereof is to be pressed down. II is the valve 
 that returns the steam from above to below the large piston, when the piston 
 is to ascend. And I is the exhaustion-valve, to carry off the steam to the 
 condenser. 
 
 When the engine makes its down-stroke, the upper valve at F is opened, 
 and admits the steam from the case to press upon the small piston, the valve 
 G being opened at the same time, which suffers the steam to pass from the 
 under side of the small to the upper side of the large piston ; and the valve I 
 is opened to make a passage from beneath the great piston to the condenser. 
 These three upper valves, F, G, I, open at the same instant of time. 
 
 When both pistons arrive at the bottom of their respective cylinders, these 
 three valves are shut altogether, and the lower steam-valve at F is opened, 
 to return the steam from above to below the small piston, the valve H doing 
 the same to the large cylinder, and both pistons return in equilibrio by the 
 counter-weight ; but the upper valve at F can be shut off at any part of the 
 stroke, according to the load of the engine. 
 
 Those who are conversant with steam-engines will per- 
 ceive, from the passing of the steam, as above described, from 
 the upper to the lower side of each of the pistons respectively, 
 that the engines at Wheal Vor, and at Wheal Abraham, are 
 at present working with a single stroke. Were these engines 
 working double, the steam would, on the down-stroke, be 
 made to pass, the same as before described, from the under 
 side of the small to the upper side of the large piston, steam 
 from the boiler in the mean time coming in upon the small 
 piston, and the under side of the large piston being open to 
 the condenser; but on the up-stroke, the action would be 
 different from what we have described, for the steam would 
 pass from the top of the small cylinder to beneath the large 
 piston, while steam would be admitted from the boiler under 
 the small piston, the top of the large cylinder being open to 
 the condenser. 
 
 The boilers which Mr, Woolf employs in his engines are 
 different from those of other engines which work with steam 
 of a low pressure, the water being contained in small cylin- 
 drical tubes of cast-iron, which are filled with water, and 
 exposed to the flame nearly in an hoi/izontal position. 
 
 Mr. Woolf has a patent for this boiler, which the specifica- 
 tion states to consist of iwo or more cylindrical vessels, 
 properly connected together, and so disposed, as to constitute 
 a strong and fit receptacle for the water intended to be con- 
 
202 
 
 THE Of'KRATIVE MECHANIC 
 
 verted into steam of a temperature and under a pressure 
 uncommonly high, and also to present an extensive portion 
 of convex surface to the current of flame and heated air from 
 a fire; likewise of other large cylindrical receptacles placed 
 above the former cylinders, and properly connected with 
 them, for the purpose of containing some water and the 
 steam. 
 
 These cylindrical vessels are set in a furnace so adapted to 
 them, as to cause the greater part of the surface of each of 
 them, or as much of the surface as may be convenient, to 
 receive the direct action of the fire, or heated air or flame. 
 
 Figs. 199 and 200 represent one of these boilers in its most simple form. 
 It consists of eight tubes marked a, made of cast-iron, or any other fit 
 metal, which are each connected with the larger cylinder A, placed above 
 them, as is shown in the side view, fig. 200, in which the same letters refer 
 to the same parts as in fig. 199. In fig. 200 is also shown the manner in 
 which the fire is made to act. The fuel rests on the grate-bars at B, and 
 the flame and heated air, being reverberated from the part above the two 
 first smaller cylinders, go under the third, over the fourth, under the fifth, 
 over the sixth, under the seventh, and partly over and partly under the 
 eighth small cylindric tube, all which tubes are full of water. The direc- 
 tion of the flame, until it reaches the last-mentioned tube, is shown by the 
 dotted curved lines and arrows. When it has reached that end of the 
 furnace, it is carried by the flue, O, to the other side of a wall, built 
 beneath the main cylinder A, in the direction of its length, and the flame 
 then returns under the opposite end of the seventh smaller cylinder over 
 the sixth, under the fifth, over the fourth, under the third, over the second, 
 and partly over and partly under the first, when it passes into the chimney. 
 The wall before-mentioned, which divides the furnace longitudinally, 
 answers the double purpose of lengthening the course which the flame and 
 heated air have to traverse, giving off heat to the boiler in the passage, and 
 also of securing the flanges, or other joinings, employed to unite the 
 smaller tubes to the main cylinder, from being injured by the fire. The 
 ends of the small cylindric tubes rest on the brickwork which forms the 
 sides of the furnace, and one end of each of them is furnished with a cover, 
 secured in its place by screws and a flanch, but which can be taken 
 off at pleasure, to allow the tubes to be cleared, from time to time, from 
 any incrustation or sediment wnich may be deposited in them. 
 
 To any convenient part of the main cylinder A, a tube is affixed, to 
 convey the steam to the steam-engine. In v^^orking with such boilers, the 
 water carried off by evaporation is replaced by water forced in by the 
 usual means for a high pressure boiler, that is, a forcing-pump ; and the 
 steam generated is carried to the place intended by means of pipes con- 
 nected with the upper part of the cylinder A. In the specification, means 
 are pointed out for applying this plan to the boilers of steam-engines 
 already in use, by ranging a row of cylinders beneath the present boiler, and 
 connecting them with each other, and with the boiler. Directions are also 
 given for constructing boilers compc-sed of cylinders disposed vertically. 
 Jn every case the tubes composing the boiler should be so combined and 
 arranged, and the furnace so constructed, as to make the fire and flame act 
 aiouiid and over the tubes, so as to embrace the largest possible quanliiy 
 >jf tlieir s.iiTace. It must be obvious to any one, that the tubes may be 
 
AND MACHINIST. 
 
 203 
 
 made of any kind of metal ; but cast-iron is the most convenient. The size 
 of the tubes may be varied ; but in every case, care should be taken not to 
 make the diameter too great ; for it must be remembered, that the larger 
 the diameter of any single tube is in such a boiler, tlie stronger it must be 
 made in proportion, to enable it to bear the same expansive force of steam 
 as the smaller cylinders. It is not essential, however, to the invention, 
 that the tubes should be of different sizes ; but the upper cylinders, espe- 
 cially the one which is called the steam cylinder, should be larger than the 
 lower ones, it being the reservoir, as it were, into which the lower ones 
 send the steam, to be thence conveyed away by the steam-pipe. The 
 following general directions are given respecting the quantity of water to be 
 kept in a boiler of this construction ; viz. it ought always to fill, not only 
 the whole of the lower tubes, but also the great steam cylinder A, to about 
 half its diameter, that is, as high as the fire is allowed to reach ; and in no 
 case should it be allowed to get so low, as not to keep the vertical necks, 
 or branches, which join the smaller cylinders to the great cylinder, full of 
 water, for the fire is only beneficially employed w'hen applied, through the 
 medium of the interposed metal, to water, to convert it into steam ; that is, 
 the purpose of the boiler would in some measure be defeatedt if any of the 
 parts of the tubes which are exposed to the direct action of the fire, should 
 present a surface of steam in their interior, instead of water, to receive the 
 transmitted heat. This must, more or less, be the case, whenever the lower 
 tubes, and even a part of the upper, are not kept filled with the water. 
 
 Respecting the furnace for this kind of boiler^ it should 
 always be so built as to give a long and waving course to the 
 flame and heated air, forcing them the more effectually to 
 strike against the sides of the tubes which compose the 
 boiler, and so to give out the greatest possible portion of 
 their heat before they reach the chimney. Unless this be 
 attended to, there will be a much greater waste of fuel than 
 necessary, and the heat communicated to the contents of the 
 boiler will be less from a given quantity of fuel. 
 
 When very high temperatures are not to be employed, the 
 kind of boiler just described is found to answer very well ; 
 but where the utmost force of the fire is desirable for pro- 
 ducing the most elastic steam, the parts are combined in a 
 manner somewhat different, though the principle is the same. 
 In the Philosophical Magazine, vol. xvii. p. 40, is a descrip- 
 tion and drawing of a boiler of this kind, two of which were 
 erected, in 1803, at Messrs. Meux's brewery. 
 
 In every case Mr. Woolf uses two safety-valves, at least, 
 in his apparatus, to prevent accidents ; a precaution which 
 cannot be too strongly enforced, as it may happen, when but 
 one is employed, that by some accident it may get locked, 
 and the engine and people about it be exposed to the danger 
 of an explosion. 
 
 In those engines of Mr. Woolf’s which we have seen, he 
 employs boilers like the one described, viz. with two small 
 tubes beneath, which are full of water, and exposed to the 
 
204 
 
 THE OPERATIVE MECHANIC 
 
 immediate action of the flame, communicating by perpen- 
 dicular necks or branches with the large cylinder above, 
 which has water in the lower part, and steam in the upper. 
 The only difference from wdiat we have above described is, 
 that the lower and upper tubes are placed in the same direc- 
 tion, instead of being at right angles to each other ; and the 
 flame proceeds in the direction of their length, instead of 
 crossing them ; the lower or water tubes are rather inclined 
 upwards. The metal of these tubes is made very thick, 
 with a view to strength and durability. 
 
 The idea of making boilers for raising strong steam by a 
 number of small tubes, which can be made stronger than one 
 large vessel, is not original with Mr. Woolf, Mr. Blakey, of 
 whom we have before spoken, having proposed it in a small 
 tract which he published in French, at the Hague, in 1776. 
 But his tubes were to be placed over each other, in an 
 inclined direction, and the water, being admitted at the upper 
 end, ran down within the heated inclined tubes, and became 
 converted into steam. 
 
 Woolf's regulating steam-valve . — Besides the common 
 safety-valves. Sir. Woolf has also introduced a valve of a new 
 construction into the steam-pipe itself, to regulate the quan- 
 tity that shall pass from the boiler. In fact, it is a self-acting 
 steam-regulator, and extremely ingenious. 
 
 A (fig. 201) is a part of the great or steam cylinder of one of Mr. Woolf’' 
 boilers ; B B, the neck or outlet for the steam, surmounted by a steam-bo? 
 C, which is joined to the neck B B, by the flanges a, a. The top or covei 
 of the steam-box C, marked with the letter D, is well secured in its place, 
 and has a hole through it for the rod of the valve to pass ; and the interioi 
 of the hole is formed to a box to hold a stuffing, and make the rod work up 
 and down steam-tight, the stuffing being kept in its place by means of a 
 collar, screwed down in the usual way, as shown in the figure. By means 
 of a pin 6, and tlie two vertical pieces c, e, the sliding-valve rod is made fast 
 to wz, which is a close cover to the hollow cylinder n n. The cover m fits 
 steam-tight into the conical seat, at the upper end of a collar o o, which is 
 made fast to tlie flange a a, and descends into the neck of the boiler, forming 
 a barrel, in which the cylinder fits close. The cylinder n n is open at 
 bottom, having a free communication with the steam in the boiler A ; and 
 it has three vertical slits cut through the sides, one of which, S, is shown irr 
 the plate. The sum of the area of all these slits or openings is equal to the 
 area of the opening of the seat or collar o o, in which the cylinder n n works. 
 
 When the steam acquires a sufficient degree of elastic force to raise the 
 valve, (that is, the cylinder n n, with its cover m, and the rod R,) together 
 with whatever weight the rod may be loaded, then the openings S, rising 
 above the steam-tight collar or seat o o, allow the steam to pass into the 
 steam-box C, and to flow off to the engine through the pipe N. But the 
 quantity of steam that passes is proportioned to the elastic force it has 
 acquired, and the weight with which the valve is loaded ; because the rise 
 of the openings, S, above the collar o o, will be in that proportion. 
 
AND MACHINIST. 
 
 205 
 
 This valve may be loaded by applying weights in any of 
 the usual methods ; but Mr. Woolf prefers the one shown in 
 the drawing, in which the upper part of the rod R is joined, 
 by means of a chain, to a quadrant of a circle Q, for the pur- 
 pose of carrying a pendulum weight Z, that admits of being 
 moved nearer to or farther from the centre of the quadrant, 
 according as the pressure of the valve is wished to be increased 
 or diminished. 
 
 As the valve rises, the weight moves upwards in the arc n w, giving a 
 continually increased resistance to the farther rising of the valve, propor- 
 tioned to the horizontal distance of the weight from the centre of Q, of 
 which the weight attains a continual increase by its rise in the arc, accord- 
 ing to the horizontal distances measured on the line Q p, pressing through 
 the centre of the weight by perpendiculars from the horizontal line. 
 
 Tims, if the weight Z presses down the valve m with a force equal to 
 20 pounds on the square inch of the aperture in o o, in its present position, 
 when it rises to the position at i, it will press with a force equal to 30 
 pounds, and at p, with a force equal to 40 pounds on the square inch ; so 
 that the rod Z may be made to serve at the same time as an index to the 
 p'erson who attends the fire, nothing more being necessary for this purpose 
 than to graduate the arc, described by the end of the rod Q Z, by experi- 
 mental trials. In the side of the steam-box C there is an opening, N, to 
 allow the steam to pass from it by a pipe to the steam-engine. 
 
 It is plain that the adjustment of the positive pressure on this valve 
 can be determined by sliding the weight Z of the pendulum to a greater 
 or less distance from the centre of motion. Again, to adjust the rate of 
 the increasing forces, so as to correspond with the increasing force of the 
 steam, the radius of the quadrant, Q, must be apportioned to the diameter 
 of the valve and the opening of the slits, S, so that the ascent of the weight, 
 Z, in its quadrant will be correspondent to the varying pressure. This 
 adjustment must be made as nearly as it can be done before the valve is 
 fixed; and to bring it afterwards to an exact regulation, the chain is 
 attached to the rod, R, by a nut and screw ; by means of which, any part 
 of the arc can be used that is found most correspondent with the varying 
 pressure, because the rate at which the resistance of the lever increases is 
 more rapid when the pendulum is near to the perpendicular, than when it 
 approaches the horizontal position. 
 
 The same effect may be produced, by making the slits in the side of the 
 cylinder narrower at the lower part of the cylinder, instead of being 
 parallel. 
 
 BELL-CRANK ENGINE. 
 
 Messrs. Boulton and Watt, soon after the expiration of 
 their patent for effecting condensation in a separate vessel, 
 introduced a form of engine, called the bell- crank engine, 
 of which we shall represent so much as is necessary to 
 exhibit the alteration in the mode of construction. 
 
 Fig. 202 is a side view of the engine. A B C is the bell-crank, there 
 being another exactly similar part on the other side, moving upon a fixed 
 centre, C ; the end A D is joined to a cross-piece which works the piston- 
 
20G 
 
 THE OPERATIV^E MECHANIC 
 
 rod in the cylinder. E serves for the air-pump, and G for the cold-water 
 pump, and the hot-water pump may be woiKed upon the same bar. The 
 connecting rod from B to II is supposed to be attached to the crank of the 
 fly-wheel at H. Engines of this description are mostly constructed with 
 slide or D valves, which are worked by the beam A C. This form of 
 engine does not possess any particular advantages otherwise than those 
 arising from compactness, which are not of sufficient weight to counter- 
 balance the increased friction. It was, in some few instances, at the 
 commencement of steam navigation, applied to boats, but it was found to 
 answer not so well as the double-beam engine. 
 
 VIBRATING ENGINE. 
 
 With a view to do away with the beam of the engine^ 
 and to communicate the motion direct from the piston-rod 
 to the fly-wheel crank, a form of engine has been constructed, 
 which, in engines of small dimensions, where the piston-rod 
 can be made of sufficient strength compared with the weight 
 of the cylinder that is to vibrate, have answered tolerably 
 well. We have seen one of about one-horse power, which 
 had been at work four years. 
 
 Fig. 203. A is the cylinder, B the piston-rod, C the crank, D the fly- 
 wheel, E a stand supporting the cylinder pivot F, which has a similar one 
 on the opposite side. One of these pivots is formed like the key of a four- 
 way cock, having a communication to the top and bottom of the cylinder. 
 By the movement of the piston, the cylinder is caused to vibrate, to turn the 
 crank and fly-wheel, and the steam passes alternately to the top and bottom 
 of the cylinder, by tlie two-way axes on which the cylinder vibrates. 
 
 When engines of this construction are formed of any 
 considerable size, there is a danger of bending the piston- 
 rod, and in vibrating, the weight of the cylinder loosens its 
 fitting in the stuffing collar of the cylinder-cap. 
 
 ROTATORY ENGIN*:. 
 
 All steam-engines as yet noticed, have their action pro- 
 duced by the movement of a piston in a cylinder, and act by 
 what is called a reciprocating motion. In engines of this 
 description, a very considerable degree of power is ex- 
 pended in arresting the motion of the different working parts, 
 and putting them into action in a direct contrary course : 
 this has claimed much attention from engineers, and many 
 attempts have been made to construct an engine in which 
 the action of the steam should operate in a continuous manner, 
 without bringing the parts to a state of rest. 
 
 The most obvious mode of attaining this object, is the producing a 
 rotatory motion. One of the most simple engines on this construction is 
 represented in fig. 204, where two sections are shown, the one at right 
 angles to the revolving shaft, the other parallel to it, the same letters in 
 both denoting the same parts. U U U U is a circular steam-case, with the 
 
STEAM EPTOIKJE 
 
 ri.z3 
 
AND MACHINIST. 
 
 207 
 
 two ends enclosed ty the circular plates V VVV, through which the shaft 
 R passes. To R is attached by four arms, S SSS, the ring PP, in which 
 the fans or flat pieces, A and B, are fixed on hinges formed steam-tight, but 
 » capable of being shut in upon the ring, as A, or opening and closing the 
 steam-course O O O O, as B. To each of these four pieces is attached a 
 tail or tripping piece, C and D, which, during their revolution, touch the 
 stud E, and raises their respective fans into the steam-way, as shown by the 
 dotted fan at A^, just after it has passed the steam aperture, I. The passage 
 to the condenser is represented at N ; G is a camb-piece attached to the 
 outer case, and fitting in a steam-tight manner upon P P P P, serving to 
 close the fans as they come round. The steam entering at I presses upon 
 G and A^, which is supposed to have been just raised to that position, and 
 forces it round, together with the ring P P P P, and the centre shaft R, until 
 it pass^ the aperture through which the steam issues to the condenser, prior 
 to which the other fan, B, passes the steam-w^ay, and obtains a position to 
 receive the action of the steam, and continue the motion. 
 
 The steam- way, O O O O, may be considered to be a cylinder bent round, 
 and the fans, as they obtrude themselves, act the part of a piston, receiving 
 the impulse of the steam always on the one side, and effecting the con- 
 densation always on the other. It being requisite that the steam-way 
 should have some teimination, the obstacle, G, is indispensable, and the 
 movement of the fans upon hinges, or some other mode, to pass such 
 obstacle, is unavoidable ; and therefore, from being thus compelled to move 
 the piece acting as a piston continually to and from its fittings, it becomes 
 extremely difficult to maintain those fittings steam-tight. This, together 
 with the steam-way not being capable of receiving the cylindrical form, 
 are inconveniences of great moment. It has been found, therefore, that in 
 maintaining engines of this construction in a working condition, great 
 difficulties arise, which hitherto have not been surmounted; and as at present 
 these engines exist to no useful end, we shall refrain from describing them 
 further. 
 
 HIGH-PRESSURE ENGINES. 
 
 If water be urged greatly by fire, steam of greater pres- 
 sure is obtained; and it has been long known, that the 
 extent of the pressure increases in a greater ratio than the 
 expenditure of heat, which has been an inducement to many 
 to attempt to use steam at excessive pressures. The pres- 
 sures generally allowed in high-pressure engines, is not more 
 than 30, 40, and seldom exceeds 50 pounds to the inch. 
 
 In engines where the pressure is so great, the weight of 
 the atmosphere is not taken into account, and the mode of 
 effecting the motion of the piston is, by allowing one end of 
 the cylinder to be open to the air, whilst the steam acts on 
 the opposite side of the piston. By this mode of operation, 
 all the parts appertaining to the promotion of condensation, 
 are dispensed with, and, consequently, the expense of making 
 those parts, the friction caused by their operations, and the 
 attention which was necessary to their well-being, is entirely 
 saved. This gives to the engine a peculiar degree of sim- 
 plicity, but it is unfortunately attended with some danger. 
 
208 
 
 THE OPERATIVE MECHANIC 
 
 Steam was applied in this mode so early as the year 1724, 
 and is described by Leupold, in his Theatrum Machinarum 
 Hydraulicarum^ vol. ii. p. 93. The engine thus described, 
 is formed with two cylinders, having pistons fitted and 
 attached to two separate beams, whose other ends are con- 
 nected with two force-pumps. Between the two cylinders is 
 a four- way cock, and as the pistons are weighed and brought 
 down to the bottom of each cylinder, it is evident that by 
 means of this cock, the steam can be let on alternately to the 
 bottom of each cylinder, whilst, at the same time, the oppo- 
 site cylinder to that in which the steam is admitted has a 
 communication with the atmosphere. Thus, by turning the 
 cocks, the two pistons are alternately raised by the steam, and 
 permitted to descend by the loading of weights attached to 
 their other end. This simple construction of high pressure 
 may be placed on a par with Newcomen's condensing 
 engine. 
 
 Mr. Watt presents to our notice this mode of using the 
 direct action of steam, in the latter part of his specification, in 
 1769 ; but the most common application of high-pressure 
 steam, of late years, is used in a form of engine invented 
 by Mr. Trevitheck, for the purpose of applying this power 
 to locomotion. He obtained a patent for it, in union with 
 Mr. Vivian, in the year 1802. This engine, from its compact- 
 ness, is peculiarly applicable to this purpose, as it requires no 
 condensing water, which would be an insurmountable bar to 
 its introduction. 
 
 Fig. 205 presents a section of this form of engine. A B is the boiler, 
 A' a safety-valve, C D the cylinder, E the four-way cock, G the passage 
 from the boiler, H the passage to the chimney, for the exit of the steam. 
 E is a four-way cock, F the passage to the top, and K the passage to the bot- 
 tom of the cylinder. M the piston, N the piston-rod, O the connecting rod, 
 joined to the cranks of the fly-wheel. The beam R is worked by the con- 
 necting rod, which has the rod of a small force-pump S attached to it, acting 
 on the other side of the boiler, and forcing water along Q U into the boiler 
 by I. The fire-place is behind the chimney, as seen in the view, and is 
 surrounded on all sides by the boiler. Fig. 206 is a section of the cylinder 
 at right angles to the section at fig. 205. The four-way cock is moved by 
 means of a lever on its axis, which is struck by a tapit upon a rod from the 
 cross-piece Ca. It must be understood that there is another connecting 
 rod and crank on the farther side of the engine, and that the beam 
 connects them. 
 
 This engine, we conceive, requires little elucidation. The 
 four-way cock permits the steam to pass alternately to the top 
 and bottom of the cylinder by the passages F and K, and 
 affords it egress by G‘ ; and the cold water coming to supply 
 the boiler, surrounding it on all sides, imbibes its heat, by 
 
AND MACHINIST. 
 
 209 
 
 which means the boiler is fed with water of a much higher 
 temperature, and the steam is condensed in H , by which a 
 more rapid exit is obtained for it. 
 
 This kind of engine was expressly intended for working 
 carriages. A locomotive engine was made by Mr. Treve- 
 theck, in South Wales, in 1804, and was tried upon the rail- 
 roads at Merthyr Tydvall. It drew after it as many carriages 
 as carried ten tons of bar iron for a distance of nine miles, 
 without any further supply of water than that contained in 
 the boiler at setting out, travelling at the rate of five 
 miles per hour. Since that period they have been tried in 
 many places upon rail-roads, but their introduction had not 
 become general until 1811, when Mr. Blenkinsop, proprietor 
 of the Middleton Coal-works, which supply the town of 
 Leeds, adopted them for conveying the coals on his rail-road. 
 Mr. Blenkinsop, when he adopted the locomotive engine, took 
 up the common rails on one side of the whole length of 
 the road, and replaced them with rails which had cogs on 
 their upper surface. These cogs are cast at the same time 
 with the rails, and are hollow beneath, to be as light as is con - 
 sistent with strength and durability. The pitch of the cogs 
 is six inches, so that each rail of three feet in length has only 
 six cogs. A wheel which is fixed on an axis which would be 
 that of the fly-wheel at one side of the carriage, works in the 
 teeth of these ^rails ; the whole machine is thus caused to 
 advance along the railway. Many fruitiest attempts have 
 been made to produce an engine capable of moving carriages 
 upon common roads; but before this can be effected, the 
 numerous parts of the engine must be made more compact, 
 and its weight considerably reduced. 
 
 Observations on the work, of steam-engine^ iit 
 
 Cornwall, from August 1811 to May 1816, inclusive, 
 
 by Messrs. Lean, 
 
 Messrs. Thomas and John Lean were appointed to the 
 general superintendence ; and the different proprietors, 
 as also the regular engineers of the respective mines, 
 engaged to give them every facility and assistance in their 
 power. Their first Monthly Report was for August, 1811, 
 and included eight engines, which had in that month consumed 
 23,661 bushels of coals, and lifted 126,126,000 pounds of 
 water one foot high, with one hushel of coals for each engine, 
 being an average duty of 15,760,000 pounds lifted one foot 
 high with each bushel of coals. In the months of September 
 and October the engines reported were nine, and in November 
 
 p 
 
210 
 
 THE OPERATIVE MECHANIC 
 
 and December twelve 3 and it now evidently appeared that 
 the regular publication of Messrs. Leans’ very useful tables 
 had already been attended by some improvements in the con- 
 dition of the engines 3 for the average duty for December, 
 1811, extracted from these tables, appears to have been 
 17 , 075,000 pounds. 
 
 In January, 1812, the number of engines reported was four- 
 teen, and by the end of that year they were increased to nine- 
 teen 3 and the average duty performed by all the engines in. 
 the last-mentioned month had advanced to 18,200,000 pounds. 
 
 In 1813, the number of engines included in the Monthly 
 Reports continued to increase, till in December they were 29, 
 and the average work 20,162,000. 
 
 During some of the months of 1814, the engines reported 
 were 32, and the average duty performed during December 
 was 19,784,000 pounds lifted one foot high with each bushel 
 of coals. 
 
 The table which is subjoined is an abstract from Messrs. 
 Leans’ Reports, and has been formed by first counting how 
 many engines are reported, as in January 1815, 32 engines 3 
 then adding up the column containing the quantity of coals 
 consumed by all the engines during the month, and putting 
 down the amount, 110,824 3 in like manner adding up the 
 column of pounds lifted by each engine one foot high by one 
 bushel of coals, the amount of which was 637,320,990 ; and 
 lastly, dividing the latter quantity by 32, the number of 
 engines at work, to obtain the average duty performed, viz. 
 19,916,250 pounds. 
 
 TABLE. 
 
 
 Number of 
 Engines re- 
 ported. 
 
 Bushels of 
 coals con- 
 sumed by all 
 the 
 
 engines. 
 
 Bushels of 
 coals upon 
 which the 
 report is 
 founded. 
 
 Pounds of water 
 lifted one foot 
 high by the 
 coals so 
 reported. 
 
 Average of 
 pounds lifted 
 one foot high 
 with each 
 bushel of coals 
 
 1811. August 
 
 8 
 
 23,661 
 
 8 
 
 126,126,000 
 
 15,760,000 
 
 September 
 
 9 
 
 25,237 
 
 9 
 
 125,164,000 
 
 13,900,000 
 
 October 
 
 9 
 
 24,487 
 
 0 
 
 121,910,000 
 
 13,540,000 
 
 November 
 
 12 
 
 30,998 
 
 12 
 
 189,340,000 
 
 15,770,000 
 
 December 
 
 12 
 
 39,545 
 
 12 
 
 204,907,000 
 
 17,075,000 
 
 1812. January 
 
 14 
 
 50,089 
 
 14 
 
 237,661,409 
 
 16,972,000 
 
 February 
 
 15 
 
 54,349 
 
 15 
 
 260,514,000 
 
 1 7,900,000 
 
 March 
 
 16 
 
 59,140 
 
 16 
 
 274,222,000 
 
 17,138,000 
 
 April 
 
 i — 
 
 16 
 
 62,384- 
 
 16 
 
 276,233,000 
 
 17,260,000 
 
AND MACHINIST. 
 
 211 
 
 Table continued. 
 
 
 Number of 
 Engines re- 
 ported. 
 
 Bushels of 
 coals con- 
 sumed by all 
 the 
 
 engines. 
 
 Bushels of 
 coals upon 
 which the 
 report is 
 founded. 
 
 Pounds of water 
 lifted one foot 
 high by the 
 «'oals so 
 reported. 
 
 Average of 
 : pounds lifted 
 one foot high 
 with each 
 bushel of coals 
 
 1812. May 
 
 16 
 
 51,903 
 
 16 
 
 273,546,000 
 
 1 7,096,000 
 
 June 
 
 17 
 
 50,410 
 
 17 
 
 288,076,000 
 
 16,940,000 
 
 July 
 
 17 
 
 51,574 
 
 17 
 
 300,441,000 
 
 17,677,000 
 
 August 
 
 17 
 
 44,256 
 
 17 
 
 314,753,000 
 
 18,510,000 
 
 September 
 
 18 
 
 46,536 
 
 18 
 
 348,396,000 
 
 19,355,000 
 
 October 
 
 18 
 
 53,941 
 
 18 
 
 321,900,000 
 
 17,883,000 
 
 November 
 
 21 
 
 57,176 
 
 21 
 
 381,460,000 
 
 18,160,000 
 
 December 
 
 19 
 
 55,784 
 
 19 
 
 341,803,000 
 
 18,200,000 
 
 1813. January 
 
 19 
 
 60,400 
 
 19 
 
 363,906,000 
 
 19,153,000 
 
 February 
 
 22 
 
 58,044 
 
 22 
 
 438,737,000 
 
 1 9,940,000 
 
 March 
 
 23 
 
 73,862 
 
 23 
 
 440,642,000 
 
 19,157,000 
 
 April 
 
 23 
 
 61,739 
 
 23 
 
 431,032,000 
 
 18,700,000 
 
 May 
 
 24 
 
 58,890 
 
 24 
 
 463,346,000 
 
 19,300,000 
 
 June 
 
 24 
 
 53,110 
 
 24 
 
 470,157,000 
 
 19,590,000 
 
 July 
 
 23 
 
 56,709 
 
 23 
 
 443,462,000 
 
 19,281,000 
 
 August 
 
 21 
 
 50,110 
 
 21 
 
 416,898,000 
 
 19,852,000 
 
 September 
 
 22 
 
 58,008 
 
 22 
 
 427,148,000 
 
 19,415,000 
 
 October 
 
 26 
 
 74,796 
 
 26 
 
 488,671,000 
 
 18,795,000 
 
 November 
 
 28 
 
 77,1 35 
 
 28 
 
 537,958,000 
 
 19,212,000 
 
 December 
 
 29 
 
 86,273 
 
 29 
 
 584,721,000 
 
 20,162,000 
 
 1814. January 
 
 28 
 
 91,753 
 
 28 
 
 .550,751,000 
 
 19,670,000 
 
 February 
 
 26 
 
 78,986 
 
 26 
 
 536,677,000 
 
 20,641,000 
 
 March 
 
 28 
 
 109,904 
 
 23 
 
 565,406,000 
 
 20,193,000 
 
 April 
 
 29 
 
 91,607 
 
 29 
 
 576,617,000 
 
 20,325,000 
 
 May 
 
 28 
 
 79,437 
 
 28 
 
 569,319,000 
 
 20,305,000 
 
 June 
 
 30 
 
 75,343 
 
 30 
 
 626,669,000 
 
 20,888,000 
 
 July 
 
 27 
 
 85,224 
 
 27 
 
 573,208,000 
 
 21,229,000 
 
 August 
 
 26 
 
 70,443 
 
 26 
 
 545,019,000 
 
 20,960,000 
 
 September 
 
 27 
 
 78,167 
 
 27 
 
 560,608,000 
 
 20,763,000 
 
 October 
 
 32 
 
 75,080 
 
 32 
 
 630,704,000 
 
 19,709,000 
 
 November 
 
 32 
 
 82,000 
 
 32 
 
 637,322,000 
 
 19,916,000 
 
 December 
 
 29 
 
 84,669 
 
 29 
 
 573,744,006 
 
 19,784,276 
 
 1815. January 
 
 32 
 
 110,824 
 
 32 
 
 637,320,990 
 
 19,916,250 
 
 February 
 
 33 
 
 101,667 
 
 33 
 
 710,271,250 
 
 21,523,370 
 
 March 
 
 34 
 
 117,342 
 
 34 
 
 706,071,990 
 
 20,766,820 
 
 April 
 
 35 
 
 105,701 
 
 35 
 
 695,212,340 
 
 19,863,210 
 
 May 
 
 34 
 
 107,530 
 
 34 
 
 669,299,140 
 
 20,479,350 
 
 From the foregoing table it appears that the average duty of 
 the engines reported, exclusive of WoolFs patent engine, is 
 at this time about 20 millions. 
 
 We have purposely omitted Woolfs patent engine, because 
 one of tlie ends intended to be gained by the Monthly Report 
 
 r 2 
 
212 
 
 THE OI’ERATIVE MECHANIC 
 
 of work actually done by the engines employed in the mineSy 
 particularly in pumping, was to know the comparative merit 
 of Woolf’s engine with two cylinders when contrasted with the 
 steam-engines in common use. One of Mr. Woolf’s engines 
 has been lately erected at Wheal Vor mine, of 53 inches 
 diameter in the great cylinder, (the smaller cylinder being 
 about one-fifth of the contents of the great one,) and nine 
 feet stroke. According to Messrs. Leans’ Report for May, the 
 duty performed by the engine alluded to, was 49,980,882 
 pounds lifted one foot with every bushel of coals consumed ; 
 and by letter we are informed (for the printed Report has not 
 yet reached us) that the duty performed by Woolf’s engine in 
 the month of June was 50,333,000. 
 
 Thus it appears that the average duty of the patent engine 
 for the months of May and June was fifty millions, while the 
 aggregate average duty of the other engines is only twenty 
 millions. From this it is evident that Mr. Woolf’s improve- 
 ments on the steam-engine will be productive of much benefit 
 to the mining interests of the kingdom. On some of the large 
 mines, when this engine shall have come into general use, 
 which it must do sooner or later, the saving in fuel only will 
 add to the yearly dividends among the proprietors several 
 thousand pounds sterling. Nor is this all ; the expense that 
 will thus be saved will prevent numbers of mines from 
 stopping work ; and will be the means of setting many again 
 to work which have ceased on account of the expense neces- 
 sary to keep them free from water. 
 
 By Messrs. Leans^ Report for January, (1816,) the average work of 33 
 engines was 20,694,630 pounds of water lifted one foot high for each bushel 
 of coals consumed. WoolPs engine at Wheal Vor during the same month 
 lifted 47,900,333 pounds, and his engine at Wheal Abraham 47,622,040 
 pounds one foot high with each bushel of coals. 
 
 By the Report for February, the average work of 34 engines was 
 20,667,398 pounds lifted one foot with each bushel of coals. WoolPs 
 engine at Wheal Vor lifted 45,493,303 ; and the one at Wheal Abraham 
 45,896,382 pounds one foot high with each bushel. 
 
 Having examined into the construction of the several kinds 
 of engines in general use, we shall forbear to mention the 
 steps of every speculatist who has attempted improvements 
 in this machine, and which have for years filled our pe- 
 riodical publications with plans, possessing more or less 
 ingenuity. 
 
 Calculations with respect to the power of steam are of great 
 importance ; but practical people are well aware that they 
 cannot be attended with accuracy. We have already shown 
 tlMit the mnount of actual force expended in steam-pressures. 
 
AND MACHINIST. 
 
 213 
 
 can be ascertained with great accuracy, by gauges and safety- 
 valves ; but the resulting disposable power is not so easily 
 discovered, as the friction of the various parts vary greatly 
 according to the state which they are in. The state of the 
 condensation, in condensing engines, gives a more or less 
 perfect vacuum, which will vary notwithstanding the utmost 
 vigilance. It has been generally set down, among engineers, 
 that nearly one half of the power of steam must be deducted 
 from the disposable force ; therefore, suppose an engine of 
 24 inch piston, the area of which will be 452 square inches, 
 has a perfect vacuum, as exhibited by the barometer of tlie 
 condenser, and the weight of the atmosphere, denoted by the 
 weather-barometer, be about fourteen pounds, and the steam- 
 gauge on the boiler stands at about two inches, which is an 
 indication of two pounds pressure, we may estimate that there 
 is 17 lbs. per square inch pressing upon the piston ; therefore 
 17 X 452 = 7684 lbs. on the piston, half of which being 
 deducted for allowance of friction, leaves a disposable force 
 of 3842 lbs. moving through the distance at the same rate in 
 which the piston moves ; wliich force being divided by Messrs, 
 Bolton and Watt’s estimate of a horse-power, will give the 
 nominal power of such engine. In high-pressure engines, 
 where the steam is not condensed, what is indicated by the 
 steam-gauge of the boiler only, must be estimated as the 
 power acting upon the piston. 
 
 That the increments of power take place in a quicker ratio 
 than those of the temperature, has been long known ; and 
 an ingenious mechanic of the present day has attempted to 
 use steam at very high pressures. Without entering into a 
 description of the obstacles he met with, we will briefly ob- 
 serve, that the requisite strength of the parts to withstand 
 the pressure, conjoined to the excessive heat, present ob- 
 stacles not easily to be overcome. 
 
 The reciprocating motion in steam-engines is a loss of 
 power which cannot be denied. For the momentum of the 
 beam and other parts passing in one direction have suddenly 
 to be arrested and moved in the opposite direction, which 
 produces a loss of power. Rotatory action has been sought, 
 therefore, with propriety, but has not yet been obtained with 
 advantage. 
 
 Messrs. Boulton and Watt, in the introduction of the 
 steam-engine into many works where the power of horses 
 was used, were obliged to take into consideration the number 
 of horses used for any particular purpose, in order to ascer- 
 tain the amount of force wanted. Upon the conclusion of a 
 
214 
 
 THE OPERATIVE MECHANIC 
 
 lulincrous set of experiments they decided, that a horse, 
 working eight hours a day, was capable of raising 33,000 lbs. 
 one foot high, in a minute. Therefore, by dividing the num- 
 ber of pounds an engine can lift one foot high in a minute, it 
 vrill give the amount of horses’ power to which that engine is 
 equal. 
 
 An entire view of an engine of the construction termed portable, is repre- 
 sented at fig. 207. A is the cylinder, B the air-pump, C the cola-water 
 pump, D the hot-waler pump, E the beam, F the connecting rod, G the 
 fiy-wheel, H the eccentric shaft, and I the governor. 
 
 It would occupy many volumes to describe the various forms 
 of construction of engines which have, since the knowledge of 
 the power of steam, been contrived ; and the information such 
 descriptions would convey would be, comparatively speaking, 
 of very little value, as the majority of them have arisen from 
 men ignorant of the principles of the action of the machine, 
 and whose productions should be classed as futile alterations. 
 
 In attempting any improvements, the principles of action 
 should first be taken into consideration. In condensing 
 engines the movement is effected by the alternate increase 
 and decrease of temperature, the perfection of both of which 
 js of great importance. The primary point to be aimed at, 
 therefore, is the maintaining of high temperature whilst the 
 steam is forcing, and reducing it suddenly when the conden- 
 sation is to be effected. This was taken into consideration 
 in the construction of Newcomen’s engine, and' was most 
 effectually attained by Mr. Watt. 
 
 The other parts of the engine may be examined v/ith a view 
 of improvement, by considering their weight and friction, 
 and by the substituting of a rotatory instead of a reciprocating 
 motion. 
 
 Simplicity of construction cannot be too strongly recom- 
 mended in all mechanical combinations ; for there are many 
 contrivances which would certainly be deserving of the name 
 of improvements, were they not inapplicable on account of 
 their intricacy. 
 
 Attempts havefrequently been made to avoid the use of the 
 air-pump, which takes up a considerable portion of the power of 
 an engine. A water barometer, adapted to the condenser, has 
 been sometimes adopted ; and a fall of water has been made 
 to pass over the upper edges and down the orifice of a tube, 
 forcing the air before it. The upper end of this tube com- 
 municates with the eduction pipe, and is said to support a 
 vacuum of considerable rarity. Exposing the steam which is 
 to be condensed to an increased surface by passing it along 
 

 \ 
 
 \ 
 
 
W'' 
 
T’XEraLAT.'[(r EF'I^IJsrjg 
 
 PL 25 
 
 lu q . 20 8 
 
 Nedr i Stodhy -<c 
 
AND MACHINIST. 
 
 216 
 
 tubes surrounded by water, or amongst tubes containing 
 water, has likewise been frequently adopted. Indeed the ex- 
 posure of considerable surface to receive heat in the generation 
 of steam, and the same to abstract it in condensation, have 
 been subjected to frequent trial. That an advantage is to be 
 procured by the adoption of such plans is undoubted; but to 
 attain such increased surface an intricacy in the parts, we 
 fear, must be adopted, which will more than counterbalance 
 the advantages gained. 
 
 The valves, or those parts of an engine which direct the 
 distribution of the steam, have always had the attention of 
 engineers, and, as we have shown, many elegant combina- 
 tions have resulted from their ingenuity. 
 
 In running a steam-engine, attention should be given to the 
 working parts. The cylinder should be packed with clean 
 hemp and the best tallow, and frequently examined to see 
 that the packing is in order. The steps of the fly-wheel, 
 shaft, and of the crank, beam, &c. should be frequently ex- 
 amined, and kept well oiled with sperm oil, which is the best 
 for all machinery. These parts must be kept from dust, and 
 if dry grindstones are driven in the mill, the dust must be care- 
 fully boxed off from the engine. The use of sand on the floor 
 of an engine-house should, for the same reason, be dispensed 
 with. 
 
 The method of starting an engine is, first to shut the con- 
 densing cock, then to open all the valves to let the steam 
 pass into the jacket, into the cylinder, through the eduction 
 pipe into the condenser, and out at the blow-valve, in order 
 to expel the air from all the parts, and get them to a proper 
 temperature, which will be shown by the steam issuing from 
 the blow-valve ; for previously to the parts being sufficiently 
 warmed, the steam in its progress becomes condensed. 
 
 When all the parts are heated, the injection water may be 
 let on, and a vacuum procured on one side of the piston, 
 which produces instant action. 
 
 The lever of the throttle-valve, which is ultimately to be 
 attached to the governor, should, on starting the engine, be 
 held by the hand of the attendant until the work is thrown on, 
 and the engine has acquired regular motion. 
 
216 
 
 THB OPJERATIVK MECHANIC 
 
 BROWNES VACUUM, OR PNEUMATIC ENGINE. 
 
 Having concluded our account of the steam-engine, we 
 shall now proceed to give a description of the engine above- 
 mentioned, which has recently claimed much attention from 
 the mechanical part of society. It is represented in fig. 208. 
 
 AA a beam, capable of vibrating upon a centre at B. 
 
 C and two chambers, formed of metal, of sufficient strength to resist 
 the pressure of the atmosphere (about 14 lbs. to the square inch) upon its 
 external surface, and having the caps C® suspended, one at each end of 
 the beam, capable of closing each of these chambers in an air-tight manner. 
 The chamber is shown in section. 
 
 EE and E^ E^ are two pipes, containing valves opening upwards, leading 
 and affording a communication from the vessels F and F^ with each of the 
 chambers C and C*. These vessels, F and F\, contain floats, F^ F^, attached 
 to the beam A A, by rods which receive motion from the floats ; to these 
 rods are attached the slides t ty to close alternately, at each vibration of the 
 beam, the apertures h h. The pinsj^p, attached to one of the rods from the 
 floats, give motion to the small vibrating tube R, which, by the rods R' 
 attached to the cranks in the chamber S, alternately opens and closes the 
 pipes S^, communicating with the vessels F and F^, 
 
 D D is a pipe leading from the gasometer, branching off at into 
 
 the two chambers C and for the purpose of supplying the gas that is to 
 be consumed in effecting the vacuum. This supply can be admitted or 
 shut off by means of the cocks D^, which open and close by cranks, 
 worked by the movement of the beam. 
 
 G G two other branch-pipes, supplied with gas from the gasometer, and 
 ending in a jet at each end. By the slanting direction of the ends, it is 
 evident, that the flames from these jets will, when their respective orifices 
 A A be open, protrude into the chambers C and Ch 
 
 K and are two pipes, affording a communication from the outer air to 
 the interior of each of the chambers C and C* ; their outer ends are 
 capable of being closed by means of the cranks n n, which are attached by 
 chains to the floats F^ F^. 
 
 Tlie mode of operation consists in allowing the gas to pass from the 
 gasometer along one of the branches of the pipe D D, and thence into one 
 of the chambers C or C^, (suppose C *,) where, by the jet of ignited gas play- 
 ing in the orifice h, it becomes ignited, and by its combustion rarefies and 
 expels a considerable portion of the atmospheric air from that chamber. 
 Suppose now the cap of the chamber be put dawn, and by the movement of 
 the rod attached to the float the orifice h and gas-pipe D be closed, the 
 combustion will immediately cease, and leave therein a partial vacuum. The 
 atmosphere beginning now to press upon the vessel F, will cause so much 
 of the water to pass from it into the chamber C * as will nearly compensate 
 the vacuum, when the valve through which the water passed being closed, 
 and communication between the interior of the chamber and the open air 
 effected by the opening ofKhthe water contained in the chamber flows from 
 thence through the aperture m, and affords power, by its fall and weight, to 
 the overshot water-wheel W. From hence it passes into the vessel S, and 
 finally is admitted by S* S* into F or F*, leaving the engine in a condition 
 to renew the operation. 
 
AND MACHINIST. 
 
 217 
 
 By inspecting the plate it will be seen, that when the cap of one chamber 
 croses, the several openings to the same chamber close with it : and by the 
 rising of the other end of the beam the similar openings to the other cham- 
 ber are opened, and prepared for a like operation. It will also be seen 
 that the production of this motion is attained by the rising of the two floats 
 in the chambers F and F h 
 
 The advantages to be derived from this engine, as detailed 
 in the descriptive outline of the inventor, are, 
 
 First, The quantity of gas consumed being very small, the 
 expense of working the engine is moderate. In its application 
 on land the saving will be extremely great, the cost of the 
 coal gas (deducting the value of the coke) being inconsider- 
 able. The expense of working a marine engine will certainly 
 be greater, as the gas used for that purpose must be extracted 
 from oil, pitch, tar, or some other substance equally portable, 
 yet even in this case, it will not equal the cost of the fuel 
 required to propel a steam-boat ; and as a few butts of oil will 
 be sufficient for a long voyage, vessels of the largest tonnage 
 may be propelled to the most distant parts of the world. 
 
 Secondly, ^^The engine is light and portable in its construc- 
 tion, the average weight being less than one-fifth the weight 
 of a steam-engine (and boiler) of the same power. It also 
 occupies a much smaller space, and does not require the 
 erection of so strong a building, nor of a lofty chimney. In 
 vessels, the saving of tonnage will be highly advantageous, 
 both in the smaller comparative weight and size of the 
 engine, and in the very reduced space required for fuel. 
 
 Thirdly, “ This engine is entirely free from danger. No 
 boiler being used, explosions cannot take place, and as the 
 quantity of gas consumed is so small, and the only pressure 
 that of the atmosphere, it is impossible that the cylinder can 
 burst, or the accidents incidental to steam-boats occur. 
 
 The power of the engine (being derived from the atmo- 
 spheric pressure of ten pounds and upwards upon the square 
 inch) may be increased with the dimensions of the cylinders, 
 to any extent, and always ascertained by a mercurial gauge. 
 
 ‘‘ It is scarcely necessary to allude to the well-known fact, 
 that, after deducting the friction arising from the use of the 
 air and cold-water pumps, &c. &c. the general available 
 power of the condensing steam-engine is from seven to eight 
 pounds per square inch. 
 
 The cost of the machine will be more, particularly as 
 constructed for raising water ; it is therefore peculiarly 
 adapted for draining fens, &c. or supplying reservoirs. The 
 expense of wear and tear will also be considerably less than 
 that of the steam-engine, and wheu occasionally out of order, 
 
218 
 
 THK OPERATIVE MECHANIC 
 
 it may be repaired at a trifling cost^ and with but little 
 delay/’ 
 
 In examining the effects of this engine, we cannot to a cer - 
 tain extent withhold our approbation ; for the patentee has 
 undoubtedly effected and applied a vacuum, produced by 
 ignition, in a manner different and more manageable than 
 any attempts that have hitherto come to our knowledge. 
 The probability of its entering efficiently into competition 
 with the steam-power, is a question that requires the data 
 of experience, which, in this early state of the invention, 
 cannot be procured. 
 
 We understand it is the intention of the inventor to apply 
 the effects of the vacuum thus produced to the movement of a 
 piston in a cylinder, which object will, when attained, afford 
 a much greater scope for the application of its powers, and 
 render it peculiarly applicable to locomotion. The obstacle 
 which at present suggests itself to the attainment of this end 
 is, the difficulty of procuring a rapid condensation without 
 allowing cold water to enter the cylinders at each stroke, 
 which in the present form of construction is allowed, and 
 which greatly aids the operation by keeping the chambers 
 entirely cool. Without, however, seeking for obstacles, 
 we wish the ingenious inventor success in surmounting 
 them. 
 
 ON THE STRENGTH OF MATERIALS 
 
 An accurate knowledge of the following experiments 
 made by Mr. George Rennie, Jun., and communicated by him 
 in a letter to Thomas Young, M. D. For. Sec. R. S., is of so 
 much importance in the construction of machines, that we 
 have extracted it from the Transactions of the Royal Society ; 
 to which we have annexed some useful notes by Mr. T. 
 Tredgold. 
 
 In presenting the result of the following experiments,” 
 says Mr. Rennie, trust I shall not be considered as deviating 
 from my subject, in taking a cursory view of the labours of 
 others. The knowledge of the properties of bodies which 
 come more immediately under our observation, is so instru- 
 mental to the progress of science, that any approximation to 
 it deserves our serious attention. The Royal Society appears 
 to have instituted, at an early period, some experiments on 
 
AND MACHINIST. 
 
 219 
 
 this subject, but they have recorded little to aid us. Emerson, 
 in his Mechanics, has laid down a number of rules and 
 approximations. Professor Robison in his excellent treatise 
 in the Encyclopcedia JBritaniiica, Banks on the Power of 
 Machines, Dr. Anderson of Glasgow, Colonel Beaufoy, &c. 
 are those, amongst our countrymen, who have given the 
 result of their experiments on wood and iron. The subject, 
 however, appears to have excited considerable attention on the 
 continent. A theory was published in the year 1638, Dy 
 Galileo, on the resistance of solids, and subsequently by rn^any 
 other philosophers. But however plausible these investiga- 
 tions appeared, they were more theoretical than practical, as 
 will be seen in the sequel. It is only by deriving a theory 
 from careful and v/ell-directed experiments, that practical 
 results can be obtained. It would be useless to enumerate 
 the labours of those philosophers, who, in following, or varying 
 from the steps of Galileo, have merely tended to obscure a 
 subject respecting which they had no data to proceed upon. 
 It is sufficient to enumerate the names of those who, in con- 
 junction with our own countrymen, have added their labours 
 to the little knowledge we possess. The experiments of 
 Bulfon, recorded in the Annals of the Academy of Scie7ices at 
 Paris, in the years 1/40 and 1741, were on a scale sufficiently 
 large to justify every conclusion, had he not omitted to ascer- 
 tain the direct and absolute strength of the timber employed. 
 It however appeared from his experiments, that the strength 
 of the ligneous fibre is nearly in proportion to the specific 
 gravity. Muschenbroeck, whose accuracy (it is said) entitled 
 him to confidence, made a number of experiments on wood 
 and iron, which, by being tried on various specimens of the 
 same materials, afforded a mean result considerably higher 
 than other previous authorities. Experiments have also been 
 made by Mariotte, Varignon, Perronet, Ramus, Rondelet, 
 Gauthey, Navier, Aubry and Texier de Norbeck, as also at 
 the Ecole Poly technique, under the direction of M. Prony. 
 With such authorities before us, it might be deemed presump- 
 tion in me, to offer you a communication on a subject which 
 had been previously treated of by so many able men.* But 
 
 * It is true that the subject has been considered by many able philoso- 
 phers, from Galileo down to the present period, but it is only lately that 
 the proper object of attention has been ascertained ; or at least the results 
 of their inquiries had not been brought forward in a practicable form. For 
 when Dr.T, Young published his Lectures, there was little on the subject 
 besides the intricate, and I may add unsatisfactory, investigations of Euler 
 and Lagrange. As to the resistance to fracture, which with the greatei part 
 
TIIM OPERATIVE MECHANIC 
 
 220 
 
 whoever has had occasion to investigate the principles upon 
 which any edifice is constructed, where the combination of its 
 parts are more the result of uncertain rules than sound prin- 
 ciple, will soon find how scanty is our knowledge on a 
 subject so highly important. The desire of obtaining some 
 approximation, which could only be accomplished by repeated 
 trials on the substances themselves, induced me to undertake 
 the following experiments. 
 
 A bar of the best English iron, about ten feet long, was selected and 
 formed into a lever, whose fulcrum is denoted by/, fig. 209. The hole was 
 accurately bored, and the pin turned, which suffered it to move freely. The 
 standard A was firmly secured by the nut c to a strong bed plate of cast- 
 iron, made firm to the ground. The lever was accurately divided in its 
 lower edge, which was made straight in a line with the fulcrum. A point, 
 or division D, was selected, at five inches from the fulcrum, at which place 
 was let in a piece of hardened steel. The lever was balanced by a weight, 
 and in this state it was ready for operation. But in order to keep it as level 
 as possible, a hole was drilled through a projection on the bed plate, large 
 enough to admit a stout bolt easily through it, which again was prevented from 
 turning in the hole by means of a tongue t fitting into a corresponding groove 
 in the hole. So that, in order to preserve the level, we had only to move 
 the nut to elevate or depress the bolt, according to the size of the specimen. 
 But as an inequality of pressure would still arise from the nature of the 
 apparatus, the body to be examined was placed between two pieces of steel, 
 the pressure being communicated through the medium of two pieces of thick 
 leather above and below the steel pieces, by which means a more equal 
 contact of surfaces was attained. The scale was hung on a loop of iron, 
 touching the lever in an edge only. I at first used a rope for the balance 
 weight, which indicated a friction of four pounds, but a chain diminished 
 the friction one half. Every movable centre was well oiled. Of the resist- 
 ances opposed to the simple strains which may disturb the quiescent state 
 of a body, the principal are the repulsive force, whereby it resists com- 
 pression, and the force of cohesion, whereby it resists extension. On the 
 former, with the exception of the experiments of Gauthey and Rondelet, on 
 stones, and a few others, on soft substances, there is scarcely any thing on 
 record. In the memoir of M. Lagrange, on the force of springs^ published 
 in the year 1760, the moment of elasticity is represented by a constant 
 quantity, without indicating the relation of this value to the size of the 
 spring ; but in the memoir of the year 1770, on the forms of columns, where 
 he considers a body whose dimensions and thickness are variable, he makes 
 the moment of elasticity proportional to the fourth power of the radius, in 
 observing the relations of theory and practice to accord with each other. This 
 
 of mechanical writers is the only object attended to, it is of very inferior 
 importance. 
 
 The laws of flexure constitute the chief guide in the construction of 
 buildings ; and the intention of these notes is to call the attention of experi- 
 mentalists to this part of the subject ; and as it is probable the ingenious 
 author of the experiments now before me may be tempted to resume his 
 labours, I feel certain that he will not feel displeased to have his attention 
 jcalled to some interesting points of inquiry, which he has either neglected 
 to notice, or has not given to the public. — T. T. 
 
AND MACHINIST. 
 
 221 
 
 was admitted by Euler in his memoir of 1780, in his elaborate investigation 
 of the forms of columns. Mr. Coulomb had however shown before that 
 time, how inapplicable all these calculations were to columns under com- 
 mon circumstances ; and you, sir, have repeated' the observation in your 
 lectures on natural philosophy. The results of experiments have also been 
 equally discordant; since it is deduced from those of Reynolds, that the 
 power required to crush a cubic quarter of an inch of cast-iron is 448000 
 pounds avoirdupoise, or 200 tons ; whereas by the average of thirteen ex- 
 periments made by me on cubes of the same size, the amount never exceeded 
 10392-53 lbs. not quite five tons. This maybe seen by referring to the 
 tables. Tliere were four kinds of iron used, viz. 1. Iron taken from the 
 centre of a large block, whose crystals were similar in appearance and 
 magnitude to those evinced in the fracture of what is usually termed gun- 
 metal. 2. Iron taken from a small casting, close grained, and of a dull 
 grey colour. 3. Iron cast horizontally in bars of |th inch square, 8 inches 
 long. 4. Iron cast vertically, same size as last. These castings were re- 
 duced equally on every side to i of an inch square : thus removing the hard 
 external coat usually surrounding metal castings. They were all subjected 
 to a gauge. The bars were then presumed to be tolerably uniform. The 
 weights used were of the best kind that could be procured, and as the ex- 
 periment advanced, smaller weights were used. 
 
 Averages. 
 
 14.39-66 
 
 Experiments on cast-iron in cubes of | of an inchy ^c. 
 
 Iron taken from the block whose specific gravity was 7-033. 
 
 lbs. avoirdupoise. 
 
 1454 
 
 1416 
 
 1449 
 
 2116 
 
 On specimens of different lengths. Specific gravity of iron 6-977. 
 
 1922 
 2310 
 
 
 
 
 >88 
 
 Ixf 
 
 
 
 slipped with 
 with 
 
 1863 lbs. filed flat, and crushed 
 
 1 X # 
 i X 4 
 
 ditto, 
 
 . 149.5 ditto ,, 
 
 ditto ...... 
 
 
 
 ditto 
 
 
 ixi 
 
 ditto 
 
 
 ditto ...... 
 
 
 2363 
 
 2005 
 
 1407 
 
 1743 
 
 1594 
 
 1439 
 
 /ipril 23, 1817. 
 
 Experiments on cubes of | of an inch taken from the 
 block. 
 
 9773.5 
 
 10114 
 
 Castings, horizontal. Specific gravity 7-113. 
 
 Vertical castings. Specific gravity 7 '07 4.. 
 bottom of vertical bar 
 
 \i>^i 
 
 11136-75^ 
 
 ) fxf 
 
 l:|rx | full size. Scale broke with 10294 ; tried 
 L again 
 
 10561 
 
 9596 
 
 9917 
 
 9020 
 
 10432 
 
 10720 
 
 10605 
 
 8699 
 
 12665 
 
 10950 
 
 11088 
 
 9844 
 
 llOOS 
 
THE OPERATIVE MECHANIC 
 
 222 
 
 Averages. ^ lbs. avoifdup0)8e> 
 
 A prism, having a logarithmic curve for its limits, resembling a 
 column ; it was ^ of an inch diameter by one inch long, broke 
 with 6954 
 
 April 28i/[. Trials on prisms of different lengths. 
 
 9982-0 If 
 
 horizontal 
 
 ditto 
 
 ditto, bad trial, 9006 lbs. 
 
 vertical 
 
 ditto 
 
 f x| 
 ixf 
 
 ^ X § 
 
 April 2dth. Horizontal castings. 
 
 or one inch long, 
 
 9455 
 
 9374 
 
 9938 
 
 10027 
 
 9006 
 
 8845 
 
 8362 
 
 6430 
 
 6321 
 
 ix i 
 ix| 
 T X I 
 
 ixf 
 
 Vertical castings. 
 
 a small defect in the specimen 
 
 or one inch. 
 
 9328 
 
 8385 
 
 7896 
 
 7018 
 
 6430 
 
 Experiments on different ynetals. 
 
 f x:|^ cast copper, crumbled with 7318 
 
 f fine yellow brass reduced with 3213- J with .... 10304 
 
 ^xi wrought copper ^.... 3427's^ 6440 
 
 ^X:J cast tin tV**** 552'^ 966 
 
 f x|^ cast lead f 483 
 
 The anomaly between the three fii'st experiments on f cubes, and the two 
 second of a ditferent length, can only be accounted for, on the difficulty of re- 
 ducing such small specimens to an equality. The experiments on ^ inch prisms 
 of different lengths give no ratio. The experiments on f inch cubes, taking an 
 average of the three first in each, give a proportion between them and the three 
 on f cubes, 
 
 as 1 : 6*096 in the block castings 
 as 1 : 7-352 in the horizontal ditto 
 as 1 : 8 035 in the vertical ditto. 
 
 In several cases the proportion is as the cubes. 
 
 The vertical cube castings are stronger than the horizontal cube castings. 
 
 The prisms usually assumed a curve similar to a curve of the third order, 
 previous to breaking. 
 
 The experiments on the different metals give no satis- 
 factory results. The difficulty consists in assigning a 
 , value to the different degrees of diminution. When com- 
 pressed beyond a certain thickness^ the resistance becomes 
 enormous. 
 
 Experiments on the suspension of bars. 
 
 The lever was used as in the former case, but the metals Avere held by nippers. 
 They were made of wrought-iron, and their ends adapted to receive the bars, 
 which, by being tapered at both extremities, and increasing in diameter from 
 the actual section, (if I may so express it,) and the jaws of the nippers being 
 confined by a hoop, confined both. 'J'he bars, which Avere six inches long, and 
 i square, Avere thus fairly and firmly grasped. 
 
and machinist. 
 
 223 
 
 No. 
 
 45 f incli, cast iron bar, horizontal 
 
 46 i do. do. vertical 
 
 47 I: do. cast steel previously tilted 
 
 48 f do. blister steel, reduced per hammer .... 
 
 49 f do. shear steel, do. do 
 
 50 ^ do. Swedish iron, do. do 
 
 51 j do. English iron, do. do 
 
 52 f do. hard gmi'metal, mean of two trials .... 
 
 53 f do. wrought copper, reduced per hammer . . 
 
 54 j do. cast copper 
 
 55 f do. fine yellow brass 
 
 56 f do. cast tin 
 
 57 ^ do. cast lead 
 
 April 30. 1817. 
 }l“}il»3'5 los. 
 
 8391 
 
 8322 
 
 7977 
 
 4504 
 
 3492 
 
 2273 
 
 2J12 
 
 1192 
 
 1123 
 
 296 
 
 114 
 
 Remarks on the last experiments. 
 
 The ratio of the repulsion of the horizontal cast cubes to the cohesion of 
 horizontal cast bars, is 8*65 : 1. 
 
 The ratio of the vertical cast cubes to the cohesion of the vertical cast bars, 
 is as 9*14 ; 1. 
 
 The average of the bars, compared with the cube. No. 16, is as 10‘611 : 1. 
 
 The other metals decrease in strength, from cast steel to cast lead. 
 
 The stretching of all the wrought bars indicated heat. 
 
 The fracture of the cast bars was attended with very little diminution of 
 section, scarcely sensible. 
 
 The experiment made by M. Prony (which asserts, that by 
 making a slight incision with the file, the resistance is 
 diminished one half) was tried on a J inch bar of English 
 iron ; the result was 2920 lbs., not a sixth part less. 
 
 This single experiment, however, does not sufficieiitly dis- 
 prove the authority of that able philosopher, for an incision is 
 but a vague term. The incision I made might be about the 
 fortieth part of an inch. 
 
 Experiments on the twist of i inch bars. 
 
 To effect the operation of twisting oflF a bar, another apparatus was prepared: 
 it consisted of a wrought-iron lever two feet long, ha^iing an arched head about 
 l-6th of a circle, of four feet diameter, of which the lever represented the 
 radius ; the centre round which it moved had a square hole made to receive the 
 end of the bar to be twisted. The lever was balanced as before, and a scale 
 hung on the arched head ; the other end of the bar being fixed in a square hole 
 in a piece of iron, and that again in a vice. The undermentioned weights 
 represent the quantity of weight put into the scale. 
 
 May 30, 1817. 
 
 On twists close to the bearing, cast horizontal. 
 
 No. ^ lbs, oz. 
 
 58 I: in bars, twisted as under with 10 14 in the scale, 
 
 59 ^ do. bad casting 8 4 
 
 60 i do. 10 11 
 
 Average 9 1 5 
 
 Cast vertical. 
 
 61 i 10 8 
 
 62 i 10 13 
 
 63 I 10 11 
 
 Average 10 Id 
 
224 
 
 THE OPERATIVE MECHANIC 
 
 On different metals. 
 
 No. 
 
 64 Cast steel 
 
 65 Shear steel 
 
 66 Blister steel 
 
 67 English iron, wrought 
 
 68 Swedish iron, wrought 
 
 69 Hard gun-inetal 
 
 70 Fine yellow brass. 
 
 71 Copper, cast 
 
 72 Tin 
 
 73 Lead 
 
 lbs. oz. 
 
 17 9 in the scale. 
 
 17 1 
 
 16 11 
 10 2 
 9 8 
 5 0 
 4 11 
 4 5 
 1 7 
 
 1 0 
 
 No. 
 
 74 f 
 
 75 i 
 
 76 i 
 
 On twists of different lengths. 
 
 Horizontal. 
 
 Weight in scale. 
 
 by ^ long 7 3 
 
 by ^ do 8 1 
 
 by 1 inch do 8 8 
 
 Vertica’. 
 
 No. Weight in scale. 
 
 77 f by do 10 1 
 
 78 i by I do 8 9 
 
 79 i by 1 inch do 8 5 
 
 Horizontal twists at 6 from the bearing. 
 
 80 by 6 inches long 10 9 
 
 81 ^ by do. do 9 4 
 
 82 by do. do.. . * 9 7 
 
 No. 
 
 83 ^ 
 
 84 ^ 
 
 85 i 
 
 Twists of ^ inch square bars, cast horizontally. 
 
 qrs. Ibs.oz. 
 
 close to the bearing 3 9 12 end of the bar hard. 
 
 do. 2 18 0 middle of the bar. 
 
 at 10 inches from bearing, lever in the \ 
 middle j 
 
 1 24 0 
 
 On tivists of different materials. 
 
 These experiments were made close to the bearing, and the weights were 
 accumulated in the scale until the substances were wrenched asunder. 
 
 No. 
 
 Weight in scale. 
 
 No. 
 
 Weight in scale. 
 
 86 Cast steel 
 
 19 
 
 9 
 
 91 Hard gun-metal . 
 
 
 0 
 
 87 Shear steel 
 
 17 
 
 1 
 
 92 Fine yellow brass. , 
 
 
 11 
 
 88 Blister steel 
 
 
 11 
 
 93 Copper 
 
 
 5 
 
 89 English iron. No. 1 
 
 .... 10 
 
 2 
 
 94 Tin 
 
 
 7 
 
 90 Swedish iron 
 
 
 8 
 
 95 Lead 
 
 
 0 
 
 Remarks. 
 
 Here the strength of the vertical bars still predominates. 
 
 The average of the two taken conjointly, and compared with a similar 
 case of i inch bars, gives the ratio as the cubes, as was anticipated. 
 
 In the horizontal castings of different lengths, the balance 
 is in favour of the increased lengths ; but in the vertical cast- 
 ings, it is the reverse. In neither is there any apparent ratio. 
 In the horizontal castings at six inches from the bearing, 
 there is a visible increase, but not so great as when close to 
 the bearing. 
 
 June 4, 1817. Miscellaneous experiments on the crush of one cubic inch. 
 
 No. lbs. avoirdiipoise. 
 
 96 Elm 1284 
 
 97 American pine 1606 
 
 98 White deal 1928 
 
 99 English oak, mean of two trials 3860 
 
 100 Ditto, of 5 inches long, slipped with 2572 
 
AND MACHINIST- 
 
 225 
 
 )fc avoirdi.poiip. 
 
 101 English oak, of four indies long, slipped with 5147* 
 
 102 A prism of Portland stone 2 inches long 805 
 
 103 Ditto, statuary marble 3216 
 
 104 Craig Leith 8688 
 
 In the following experiments on stones, the pressure was communicated 
 
 through a kind of pyramid, the base of which rested on the hide leather, and 
 that on the stone. t The lever pressed upon the apex of the pyramid. Cubet. 
 of one and a half inch. 
 
 No. Spec. grav. ll>s. avoir. 
 
 105 Chalk 1127 
 
 106 Brick of a pale red colour 2 085 1265 
 
 107 Roe-stone, Gloucestershire 1449 
 
 108 Red brick, mean of two trials 2’168 1817 
 
 109 Yellow face baked Hammersmith paviors, 3 times 2254 
 
 110 Burnt do. mean of two trials 324.3 
 
 1 1 1 Stourbridge or fire brick 3864 
 
 112 Derby grit, a red friable sand-stone 2 316 7070 
 
 113 Ditto, from another quarry 2-428 9776 
 
 114 Killaly white freestone, not stratified 2*423 10264 
 
 115 Portland 2-428 10284 
 
 116 Craig Leith, white freestone 2*452 12346 
 
 June 5, 6, and 7, 1817. 
 
 117 Yorkshire paving with the strata 2*507 1285o 
 
 118 Ditto, do. against the strata 2*507 12836 
 
 119 White statuary marble not veined 2*760 13632 
 
 120 Bramley Fall sandstone, near Leeds, with strata 2*506 13632 
 
 121 Ditto, against the strata 2*506 13632 
 
 122 Cornish granite 2*662 14302 
 
 123 Dundee sandstone or brescia, two kinds 2 530 14918 
 
 124 A two -inch cube of Portland 2*423 14918 
 
 125 Craig Leith with the strata 2*452 15560 
 
 126 Devonshire red marble, variegated 16712 
 
 127 Compact limestone 2*584 17354 
 
 128 Peterhead granite hard close grained 18636 
 
 129 Black compact limestone, Limerick 2*598 '19924 
 
 130 Purbeck 2*599 20610 
 
 131 Black Brabant marble 2*697 20742 
 
 132 Very hard freestone 2.528 21254 
 
 133 White Italian veined marble 2*726 21783 
 
 134 Aberdeen granite, blue kind 2*625 24556 
 
 N. B. The specific gravities w*ere taken with a delicate balance, made by 
 
 Creighton of Glasgow, all with the exception of two specimens, which were b) 
 accident omitted. 
 
 Remarks. 
 
 In observing the results presented by the preceding table, 
 it will be seen that little dependence can be placed on the 
 
 * The experiments on woods are considerably below those of other writers ; 
 and it appears singular that the four-inch specimen should be stronger than the 
 shorter length. According to Rondelet’s experiments, to crush a cubic inch of 
 oak it required from 5000 to 6000 lbs. avoirdupoise 
 of fir - from 6000 to 7000 lbs. 
 
 In the former the pieces Avere composed one-third of their length ; in the^latter 
 one-half of their length (Rondelet’s L'Art de Btdir, tom. iv. p. 67.) Mr. Rennie 
 has not stated the diminution of length. 
 
 t It certainly would have been preferable to have placed a hard and rigid 
 substance next the stone, in order to secure equality of pressure. 
 
 Q 
 
226 
 
 THE OPERATIVE MECHANIC 
 
 specific gravities of stones, so far as regards their repulsive 
 powers, although the increase is certainly in favour of their 
 specific gravities. But there would appear to l)e some unde- 
 fined law in the connection of bodies, with which the specific 
 gravity has little to do. Thus, statuary marble has a specific 
 gravity above Aberdeen granite, yet a repulsive power not 
 much above half the latter. Again, hardness is not altogether 
 a characteristic of strength, inasmuch as the limestones, which 
 yield readily to the scratch, have nevertheless a repulsive 
 power approaching to granite itself. 
 
 It is a curious fact in the rupture of amorphous stones, 
 that ]>yramids are formed, having for their base the upper 
 side of the cube next the lever, the action of which displaces 
 the sides of the cubes, precisely as if a wedge had operated 
 lietween them. I have preserved a number of the specimens, 
 the sides of which, if continued, might cut the cubes in the 
 direction of their diagonals. 
 
 Experiments made on the transverse strain of cast bars, the ends loose, 
 June ^th, I 8 I 7 .* 
 
 Weight of the dist. of bearings, lbs. 
 bars, lbs. oz. ft. in. avoir. 
 
 135 Bar of 1 inch square 12 6 3 0 897 
 
 136 /Do. of 1 inch do 9 8 2 8 1086 
 
 137 t Half the above bar 1 4 2.520 
 
 138 / Bar of 1 inch square, through the diagonal 2 8 2 8 851 
 
 139 ( Half the above bar 1 4 1587 
 
 140 /Bar of 2 inches deep, by f inch thick 9 5 2 8 2185 
 
 141 i Half the above bar 1 4 4508 
 
 * A bar of cast-iron, from a Welsh foundry, which did not yield easily to 
 the file, was laid upon supports exactly three feet apart ; the bar was an inch 
 square, and when 308 pounds were put into a scale suspended from the middle, 
 of its length, the deflexion was found to be 3-16ths of an inch ; whence the 
 height of the modulus of elasticity is 6,386,688 feet. The experiment was 
 made by Mr. R. Ebbels, at Garnons, near Hereford. A joist of cast-iron, nine 
 inches deep, resembling in form the letter I, was laid upon supports 19 feet 
 apart, first on its edge, when the deflexion from its own weight was 3-40ths of 
 an inch. It was then laid flatwise, and the deflexion from its own weight was 
 3J inches. The castings were from Messrs. Dowsons’ foundry, Edgware-road. 
 The iron yielded easily to the file. The height of the modulus of elastifcity 
 according to the experiment on the 
 
 joist flatwise is 5,100,000 feet, 
 
 -on the edge is 5,700,000 feet. 
 
 The deflexion being very small when the joist was on its edge, perhaps it was 
 not measured with the necessary degree of accuracy, as a very small error 
 would cause the difference in the result. The following tablet contains the 
 value of the modulus for cast-iron, according to the experiments above stated. 
 
 Height of modulus in feet. 
 
 Cast-iron (Welsh) 6,386,688 
 
 Cast-iron 3,500,000 
 
 Cast-iron, grey French 5,095,480 
 
 Cast-iron, soft do 4,247,000 
 
 Cast-iron 5,700,000 
 
 Experimentalists. 
 
 Ebbels. 
 
 Banks. 
 
 Rondelet. 
 
 Rondelet. 
 
 By my trial. 
 
AND MACHINIST, 
 
 227 
 
 bars,” 
 
 142 fBar 3 inches deep, bv|- inch thick 9 
 
 143 XHalfthebar 
 
 144 Bar 4 inches, by | inch thick . . . . 
 
 145 Equilateral triangles with the angle up and down. 
 
 146 r Edge or angle up 9 
 
 147 J angle down. ^ 
 
 148 S Half the first bar 
 
 149 (_Half the second bar 
 
 150 A feather-edged or bar was cast whose dimensions were 
 
 151 f 2 inches deep by 2 wide 10 0 
 
 152 t Half of ditto 
 
 N. B. All these bars contained the same area, though differently distributed as 
 to their forms. 
 
 1 of thadis. 
 
 of bearings. lb». 
 
 lbs. oz. 
 
 ft. 
 
 in. 
 
 avoir. 
 
 9 15 
 
 2 
 
 8 
 
 3588 
 
 .... 
 
 1 
 
 4 
 
 6854 
 
 9 7 
 
 r. 
 
 8 
 
 3979 
 
 9 11 
 
 2 
 
 8 
 
 1437 
 
 9 7 
 
 2 
 
 8 
 
 840 
 
 .... 
 
 1 
 
 4 
 
 3059 
 
 IS were 
 
 
 4 
 
 1656 
 
 edge up 2 
 
 8 
 
 3105 
 
 Experiments made on the bar of 4 inches deep by f inch thick, by giving it 
 different forms, the bearings at 2 feet 8 inches, as before. 
 
 ^ No. ^ lbs. lbs. 
 
 * 153 Bar formed into a semi-ellipse, weighed 7 4000 
 
 154 Ditto, parabolic on its lower edge 3860 
 
 Ditto, of 4 inches deep by ^ inch thick 3979 
 
 Experiments on the transverse strain of bars, one end made fast, the weight 
 being suspended at the other, at 2 feet 8 inches from the bearing. 
 
 155 An inch square bar bore 280 
 
 156 A bar 2 inches deep by J an inch thick 539 
 
 157 An inch bar, the ends made fast 1 173 
 
 The paradoxical experiment of Emerson was tried, which states that by 
 cutting off a portion of an equilateral triangle (see page 114 of Emerson’s 
 Mechanics) the bar is stronger than before, that is, a part stronger than the 
 whole. The ends were loose at two feet eight inches apart as before. The edge 
 from which the part was intercepted Avas lowermost, the weight was applied on 
 the base aboA'e, it broke with 1129 pounds, whereas in the other case it bore 
 only 840 pounds. 
 
 Remarks on the transverse strain. 
 
 Banks makes his bar from the cupola, Avhen placed on bearings three feet 
 asunder , and the ends loose, to bear 864 lbs. 
 
 Now all my bars were cast from the cupola, the difference was therefore 33 lbs. 
 
 I adapted a space of two feet eight inches asunder, as being more convenient 
 for my apparatus. The strength of the different bars, all cases being the same, 
 approaches nearly to the theory, Avhich makes the comparative values as the 
 breadths multiplied into the squares of the depths. Tlie halves of the bars 
 were tried, merely to keep up the analogy. The bar of four inches deep, how- 
 ever, falls short of theor)"^ by 365 pounds. It is evident e cannot extend the 
 system of deepening the bar much further, nor does the theory exactly maintain 
 in the case of the equilateral triangle by 243 lbs. 
 
 Tlie diagonal position of the square bar, is actually worse than when laid on 
 its side, contrary to many assertions. 
 
 The same quantity of metal in the feather-edged bar was not so strong as 
 in the four-inch bar. 
 
 The semi-elliptical bar, exceeded the four-inch bar, although taken out of it. 
 The parabolic bar came near it. 
 
 The bar made fast at both ends, I suspect must have yielded, although the 
 ends were made fast by iron straps. The experiments from Emerson, on solids 
 of different forms, might be made ; but the time and trouble these experiments 
 have already cost, have compelled me to relinquish further pursuits for the 
 present. If, however, in the absence of better, they are worthy of the indul- 
 gence of the Royal Society, it will not only be a consolation to me that my 
 
228 
 
 THE OPERATIVE MECHANIC 
 
 labours merit their attention, but a further inducement to prosccut' the 
 investigation of useful facts, which, even in the present advanced state of 
 knowledge, will yet admit of addition. 
 
 The science of construction is yet in its infancy, and cer- 
 tainly requires many additions. The first experiments on 
 the strength of materials appear to have been made before 
 the Royal Society ; and there can be no doubt that a favour- 
 able reception will be given to any others that will tend to 
 elucidate a subject which is likely to form one of the prin- 
 cipal branches of an engineer’s education ; as he must either 
 proceed on the principle of science, or be directed by a 
 feeling of fitness, which is to be acquired only by devoting a 
 lifetime to the practice of his art. 
 
 HYDRAULIC ENGINES, 
 
 This term is applicable to all machines driven by the force 
 of water ; consequently we have, under the article Water- 
 mills,” already treated of the most extensive branch of these 
 machines. Those which have now to claim our attention, 
 are such as could not with propriety be introduced under 
 that head, and which are, upon the whole, of too much im- 
 portance, both with respect to the conve}^ance of water, and 
 as accessions to mechanical combinations, to be entirely 
 omitted. 
 
 1. Of all the hydraulic machines invented by the ancients, 
 though Archimedes’ screw is the most curious, the tympanum 
 raises the greatest quantity of water at once. 
 
 It consists of a great hollow wheel, composed of several planks joined 
 together, and well calked and pitched, forming, as its name imports, a 
 kind of barrel or drum, and having an horizontal axle on which it 
 turns. The interior is divided by eight partitions into as many equal 
 spaces or cells, each of which has an orifice of about half a foot in the rim 
 of the drum or wheel, shaped so as to facilitate the admission of the 
 water : there are, moreover, eight hollow channels running contiguous 
 to each other and parallel to the axle of the wheel, each corresponding to 
 one of the eight large cells, through which the water passes from the cells 
 just mentioned, and after running along the channels to a convenient 
 d'.stance escapes through orifices into a reservoir placed just beneath the 
 axle of the wheel. Thus the water is elevated through a vertical space 
 equal to the radius of the hollow wheel. When the tympanum is used to 
 raise water from a running stream, it is moved by means of float-boards 
 impelled by the stre.rm; but when employed to raise stagnant water, it 
 receives motion from a foot-wheel placed on the same shaft, which is, 
 as we have alread v described under the article “ Foot-mill,’' turned by men 
 walking inVide. The chief defect of this machine is, that it raises the water 
 
AND MACHINIST. 
 
 229 
 
 in the most disadvantageous situation possible : ^ov the load being found 
 always towards the extremity of a radius of the wheel, the arm of the 
 effective lever which answers to it, increases through the whole quadrant the 
 water describes in passing from the bottom of the wheel to the altitude of 
 its centre ; so that the power must act in like manner as if it were applied 
 at a winch-handle, and, consequently, cannot act uniformly. 
 
 2. M, de la Faye, to remedy this defect^ devised a ma- 
 chine which may here be described, together with the process 
 of reasoning that led to it. 
 
 When we develope the circumference of a circle, a curve is described 
 (i. e. the involute) of which all the radii are so many tangents to the circle, 
 and are likewise all respectively perpendicular to the several points of the 
 curve described, which has for its greatest radius a line equal to the 
 periphery of the circle evolved. The truth of which is shown by geometri- 
 cians when treating of the genesis of evolute and involute curves. 
 
 Hence, having an axle whose circumference a little exceeds the height 
 which the water is proposed to be elevated, let the circumference of the 
 axle be evolved, and make a curved canal whose curvature shall coincide 
 throughout exactly with that of the involute just formed : if the further 
 extremity of this canal be made to enter the water that is to be elevated, 
 and the other extremity abut upon the shaft which is turned ; then in the 
 course of the rotation the water will rise in a vertical direction, tangential 
 to the shaft, and perpendicular to the canal in whatever position it may 
 be. Thus the action of the weight answering always to the extremity of a 
 horizontal radius will be as though it acted upon the invariable arm of a 
 lever, and the power which raises the w'eight will be always the same : and 
 if the radius of the wheel, of which this hollow canal serves as a bent spoke, 
 is equal to the height that the water is to be raised, and consequently equal 
 to the circumference of the axle or shaft, the power will be to the load of 
 water reciprocally as the radius of a circle to its circumference, or directly 
 as 1 to nearly. 
 
 In M. de la Faye's opinion, the machine ought to be composed of four of 
 these canals : but it has often been constructed with eight, as represented 
 in fig. 210. The wheel being turned by the impulsion of the stream upon 
 the float-boards, the orifices F, E, D, C, &c. of the curvilinear canals, dip one 
 after another into the water which runs into them ; and as the wheel revolves 
 the fluid rises in the canals, /, e, d, c, &c. and runs out in a stream P froin 
 the holes at O ; it is received into the trough Q, and conveyed from thence 
 by pipes. 
 
 By this construction the weight to be raised offers always 
 the same resistance, and that the least possible, while the 
 power is applied in the most advantageous manner the cir- 
 cumstances will admit of : these conditions both fulfilled at 
 the same time furnish the most desirable perfection in a 
 machine. Further, this machine raises the water by the 
 shortest way, namely, the perpendicular, or vertical ; in this 
 respect being preferable to Archimedes’ screw, where the 
 water is carried up an inclined path : and besides this, each 
 curved channel in this wheel empties all the water it receives 
 in every revolution, while the screw of Archimedes delivers 
 only a small portion of the fluid it is charged with, being 
 
230 
 
 THK OPERATIVK MECHANIC 
 
 often loaded with twenty times as much water as is discharged 
 in one rotation ; and thus requiring an enormous increase of 
 labour when a large quantity is intended to be raised by it. 
 
 The nature and advantages of this wheel evince very forci- 
 bly how far the speculations of geometers are from being so 
 unfruitful in useful applications, is often insinuated by 
 practical men. 
 
 3. The wheel just described would, we think, be the most 
 perfect of any that could be employed for raising water, had 
 it not the disadvantage attending the tympanum, which is, 
 that it can only raise water to the height of its semidiameter. 
 As in many cases water is to be raised higher than the radius 
 of any wheel can well be made for practice, we shall next 
 describe a machine called the Noria, common in Spain, 
 which raises water nearly through a diameter. 
 
 Tliis Noria consists of a vertical wheel of 20 feet diameter, on the 
 circumference of which are fixed a number of little boxes or square buckets, 
 for the purpose of raising the water out of the well, communicating with 
 the canal below, and to empty it in a reservoir above, placed by the side 
 of the wheel. The buckets have a lateral orifice, to receive and to dis- 
 charge the water. The axis of this wheel is embraced by four small 
 beams, crossing each other at right angles, tapering at the extremities, 
 and forming eight little arms. This wheel is near the centre of the 
 horse-walk, contiguous to the vertical axis, into the top of which the horse- 
 beam is fixed ; but near the bottom it is embraced by four little beams, 
 forming eight arms similar to those above described, on the axis of the 
 water-wheel. As the mule which they use goes round, these horizontal 
 arms, supplying the place of cogs, take hold, each in succession, of those 
 arms which are fixed on the axis of the water-wheel, and keep it in 
 rotation. 
 
 This machine, than which nothing can be cheaper, throws 
 up a great quantity of water; yet undoubtedly it has two 
 defects : the first is, that part of the water runs out of the 
 buckets and falls back into the well after it has been raised 
 nearly to the level of the reservoir : the second is, that a 
 considerable proportion of tlie water to be discharged is 
 raised higher than the reservoir, and falls into it only at the 
 moment when the bucket is at the highest point of the 
 circle, and ready to descend. These inconveniences are both 
 remedied by the contrivance mentioned in the next paragraph. 
 
 4. The Persian wheel is a name given to a machine for 
 raising water, which may be turned by means of a stream 
 A B acting upon the wheel C D E according to the order of 
 the letters ; (fig, 210.) 
 
 Tlie buckets «, «, a, &c. instead of being firmly fastened, are hung upon the 
 wheel by strong pins, 6, 6, 6, 6, &c. fixed in the side of the rim ; which must 
 be made as high as the water is intended to be raised above the level of that 
 part of the stream in which the wheel is placed. As the wheel turns, the 
 
PI. 2 e. 
 
 Hie hmfjth of the Lcverisiwt sho^Mi 
 
 O /—IT 
 
 
 
 BeP Phitc 
 
 r\S7 
 
 Plan of Lev^r 
 
 :LrYiD;RAi' i.:[r s 
 
 From 20.9 to 213 
 
AN1> MACHINIST. 
 
 231 
 
 buckets on the right hand go down into the water, where they are filled, 
 and return up full on the left hand, till they come to the top at K ; where 
 they strike against the end n of the fixed trough M, by which they are 
 overset, and so empty the water into the trough ; from whence it is to be 
 conveyed in pipes to any place it is intended for : and as each bucket gets 
 over the trough, it falls into a perpendicular position again, and so goes 
 down empty till it comes to the water at A, where it is filled as before. On 
 each bucket is a spring, r, which going over the top or crown of the bar m 
 (fixed to the trough M) raises the bottom of the bucket above the level of 
 its mouth, and so causes it to empty all its water into the trough. 
 
 To determine the due relation of the power and the weight so that this 
 wheel may be capable of prod ucing the greatest effect, the following may 
 be taken as a good approximation. After having fixed the diameter of the 
 wheel, which must be something greater than the altitude to which the 
 water is to be raised ; fix also upon an even number of buckets to be hung 
 at equal distances round the periphery of the wheel, and mark the position 
 of their centres of motion in such a manner that they will stand in corres- 
 ponding positions in every quarter of the circle : conceive vertical lines 
 drawn through the centre of motion of each bucket in the rising part of the 
 wheel; they will intersect the horizontal diameter of the wheel in points at 
 which, if tire buckets were hung, they would furnish the same resistance to 
 the moving force as they do when hanging at their respective places on the 
 rim of the wheel. Thus, supposing there were 18 equidistant buckets; 
 then while eight hung on each side a vertical diameter of the wheel there 
 would be eight on the other side, and two would coincide with that diameter : 
 in this case the resistance arising from all the full buckets would be the same 
 as if one bucket hung oji the prolongation of the horizontal diameter at the 
 distance of 2 sin. 20° I- 2 sin. 40° + 2 sin. 60° + 2 sin. 80°, these being 
 the sines to the common radius of the wheel. 
 
 To know the quantity of water that each bucket should contain, take f of 
 the absolute force of the stream, that is, ^ of the weight of the prism of 
 water whose base is the surface of one of the float-boards, and whose 
 height is that through which water must fall to acquire the velocity of the 
 stream ; so have we the power that should be in equilibrio with the weight 
 of water in the buckets of the rising semicircle. Then say, as the sum of 
 the sines mentioned above is to radius, so is the power just found to a 
 fourth term, the half of which will be the weight of water that ought to be 
 contained in one bucket. Lastly, as the velocity of the wheel will be to 
 that of the stream nearly as 1 to 2|-, the quantity of revolutions it makes in 
 any determinate time becomes known, and, by consequence, the quantity 
 of water the wheel will raise in the same time ; since we know the capacity 
 of each bucket, and the number of them emptied in every revolution of the 
 wheel. 
 
 5. Another contrivance for raising water similar to the 
 chain-pump^ which is described in another part of the work, 
 is an endless rope with stuffed cushions hung upon it, which, 
 by means of two wheels or drums, are caused to rise in 
 succession in the same barrel, and to cai*ry water with them. 
 From the resemblance of this apparatus to a string of beads, 
 it is usually called paternoster-work. But in this, as well as 
 the chain-pump, the magnitude of the friction is a formidable 
 practical objection. 
 
 0. Jets and fountains are not now considered as conducive 
 
232 
 
 THii OPERATIVE MECHANIC 
 
 to picturesque beauty ; nor can they be reckoned of much 
 utility, except perhaps in hot climates; we have not there- 
 fore described any in this work. But in the fountain of Hiero 
 of Syracuse, a principle is introduced which has been found 
 of great utility in larger works ; for the head of water is 
 actually lower than the orifice, but the pressure is communi- 
 cated by the intervention of a column of air : the construction 
 of this fountain is as follows : 
 
 It consists of two vessels K L M N (fig. 212) and O P Q R, which are close 
 on all sides. A tube A B, having a funnel at the top, passes through the 
 uppermost vessel without communicating with it, being soldered into its top 
 and bottom. It also passes through the top of the under vessel, where it is 
 likewise soldered, and reaches almost to its bottom. This tube is open at 
 both ends. There is another open tube S T, which is soldered into the top 
 of the under vessel and the bottom of the upper vessel, and reaches almost 
 to its top. These two tubes serve also to support the upper vessel. A 
 third tube G F is soldered into the top of the upper vessel, and reaches 
 almost to its bottom. This tube is open at both ends, but the orifice G is 
 very small. Now suppose the uppermost vessel filled with water to the 
 height E N, E e being its surface a little below T. Stop the orifice G with 
 the finger, and pour in water at A. This will descend through A B, and 
 compress the air in OPQR into less room. Suppose the water in the 
 under vessel to have acquired the surface C c, the air which formerly 
 occupied the whole of the spaces OPQR and K L e E will now be con- 
 tained in the spaces o P c C and K L e E ; and its elasticity will be in 
 equilibrio with the weight of the column of water, whose base is the surface 
 E, e, and whose height is A c. As this pressure is exerted in every part of 
 the air, it will be exerted on the surface E e of the water of the upper 
 vessel ; and if the pipe F G were continued upwards, the water would be 
 supported in it to a height e H above E e, equal to A c. Therefore, if the 
 finger be now taken from off the orifice G, the fluid will spout up through 
 it to the same height as if it had fallen through a tube whose altitude is 
 e H. So long as there is any water in the vessel KLN M there vidll be a 
 discharge through the orifice : therefore the play of the fountain will con- 
 tinue whilst the water contained in the upper vessel, having spouted out, 
 falls down through the pipe A B : the height of the water measured from 
 the basin V A W to the surface of the water in the lower vessel OPQR 
 is always equal to the height measured from the top of the jet to the 
 surface of the water in the vessel K LMN. Now, since the surface Ee 
 is always falling, and the water in the lower vessel always rising, the 
 height of the jet must coniinually decrease, till it is shorter by the depth 
 of K L M N, which is empty, added to the depth of O P Q R, which is 
 always filling ; and when the jet is fallen so low, it immediately ceases to 
 play. 
 
 7. A machine designed to raise water to a great height for 
 the irrigation of land, in such situations as have the advantage 
 of a small fall, is described in Dr. Darwin^s Phytologia: as 
 it depends on the principle of Hiero’s fountain, it may pro^ 
 perly be inserted here. 
 
 I'lg. 211 , a, b, is the stream of water. 
 
 b, c, c, represents the water-fall, supposed to be 10 feet. 
 
AND MACHINIST. 233 
 
 rf, 6f are two leaden or iron vessels, containing a certain quantity of 
 water, which may be computed to be about four gallons each. 
 
 h, i, k, ly are leaden vessels, each holding about two quarts. 
 
 o, py two cocks, each of which passes through two pipes, opening the one 
 and closing the other. 
 
 q, r, is a water-balance, that moves on its centre s, and by which the 
 two cocks o and p are alternately turned. 
 
 t, u, and w, cc, are two air-pipes of lead, both internally inch in 
 diameter. 
 
 y, z; y, z ; y, z ; are water-pipes, each being one inch in diameter. 
 
 The pipe b,e, c, is always full from the stream a, b : the small cisterns 
 gy iy I, and the large one d, are supposed to have been previously filled with 
 water. The fluid may then be admitted by turning the cock o, through the 
 pipe c, e, into the large cistern e. This water will press the air confined in 
 the cistern e up the air-pipe w, x, and will force the fluid out of the cisterns 
 g, i, I, into those marked h, k, and C. — At the same time, by opening B, the 
 water and condensed air, which previously existed in the large cistern d, 
 and in the smaller ones marked /, h, k, will be discharged at B. After a 
 short time, the water-balance, q, r, s, will turn the cocks, and exclude the 
 water, while it opens the opposite ones : the cisterns/, h, k, are emptied in 
 their turns by the condensed air from the cistern d, as the water progressively 
 enters the latter from the pipe b, c. 
 
 8. A very ingenious application of the same principle has 
 been made in the celebrated Hungarian machine^ at Chemnitz. 
 The best account we have been able to obtain of this is the 
 following : 
 
 In fig. 213, A represents the source of water elevated 136 feet above the 
 mouth of the pit. From this there runs down a pipe D of four inches 
 diameter, which enters the top of a copper cylinder B, feet high, 5 feet dia- 
 meter, and 2 inches thick, and reaches to within 4 inches of the bottom : 
 it has a cock at I. 
 
 This cylinder has a cock at Q, and a very large one at N. From its 
 top proceeds a pipe V E C, two inches in diameter, which goes 96 feet 
 down the pit, and is inserted into the top of another brass cylinder C, which 
 is 6^ feet high, four feet diameter, and two inches thick : the latter contain- 
 ing about 83 cubic feet,' which is nearly one half of the capacity of the 
 former, viz. 170 cubic feet. There is another pipe F O of four inches dia- 
 meter, which rises from within four inches of the bottom of this lower 
 cylinder, is soldered into its top, and rises to the trough Z which carries off 
 the water from the mouth of the pit. This lower cylinder communicates at 
 the bottom with the water O, which collects in the drains of the mines. A 
 large cock P serves to exclude or admit this water : another cock M at the 
 top of this cylinder communicates with the external air. 
 
 Now, suppose the cock I shut, and all the rest open ; the upper cylinder 
 will contain air, and the lower cylinder will be filled with water, because it 
 is sunk so deep that its top is below the usual surface of the mine-waters. 
 Shut the cocks Q, N, M, P, and open the cock I. The water of the source 
 A must run in by the orifice J, and rise in the upper cylinder, compressing 
 the air above it and along the pipe V E C, and thus acting on the surface 
 of the water in the lower cylinder. It will therefore cause it to rise gradually 
 in the pipe O F, where it will always be of such a height that its weight 
 balances the elasticity of the compressed air. Suppose no issue given to 
 the air from the upper cylinder, it would be compressed into one-fifth of its 
 bulk by the column of 136 feet high; for a column of 34 feet nearly 
 
234 
 
 THE OPERATIVE MECHANIC 
 
 balances the ordinary elasticity of the 'air. Therefore, when there is an 
 issue given to it through the pipe VEC, it will drive the compressed air 
 along this pipe, and it will expel w'ater from the lower cylinder. When 
 the upper (cylinder is full of water, there will be 34 cubic feet of water 
 expelled from the lower cylinder. If the pipe O P had been more than 
 136 feet long, the water would have risen 136 feet, being then in equilibrio 
 with the water in the feeding pipe D by the intervention of the elastic air ; 
 but no more water w'ould have been expelled from the lower cylinder than 
 what fills this pipe. But the pipe being only 96 feet high, the water will 
 be thrown out at Z with a considerable velocity. If it were not for the 
 great obstructions which water and air must meet wdth in their passage 
 along pipes, it would issue at Z with a velocity of more than 50 feet per 
 second. It issues however much more slowly, and at last the upper 
 cylinder is full of water, and the water would enter the pipe V E and enter 
 the lower cylinder, and, without displacing the air in it, would rise through 
 the discharging pipe O P, and run off to waste. To prevent this there 
 hangs in the pipe V E a cork ball or double cone, by a brass wire which 
 is guided by holes in two cross pieces in that pipe. When the upper 
 cylinder is filled with w^ater, this cork plugs up the orifice V, and no water 
 is wasted; the influx at J now stops. Ikit the lower cylinder contains com- 
 pressed air, which would balance water in a discharging pipe 1 36 feet high, 
 whereas O P is only 96. Therefore the water will continue to flow at Z till 
 the air has so far expanded as to balance only 96 feet of water, that is, till 
 it occupies one-half of its ordinary bulk, that is, one-fourth of the capacity 
 of the upper cylinder, or 42 ^ cubic feet. Therefore 42§ cubic feet will be 
 expelled, and the efflux at Z will cease ; and the lower cylinder is about 
 one-half full of water. When the attending workman observes this, 
 he shuts the cock I. He might have done this before, had he known 
 when the orifice V was stopped ; but no loss ensues from the delay. At 
 the same time the attendant opens the cock N the w^ater issues with great 
 violence, being pressed by the condensed air from the lower cylinder. It 
 therefore issues with the sum of its own weight and of this compression. 
 These gradually decrease together, by the efflux of the water and the expan- 
 sion of the air; but this efflux stops before all the water has flowed out; for 
 there is 42 ^ feet of the low^er cylinder occupied by air. This quantity of 
 water remains, therefore, in the upper cylinder nearly : the workman knows 
 this, because the discharged water is received first of all into a vessel con- 
 taining three-fourths of the capacity of the upper cylinder. Whenever this 
 is filled, the attendant opens the cock P by a long rod which goes down 
 the shaft ; this allows the water of the mine to fill the lower cylinder, and 
 the air to get into the upper cylinder, which permits the remaining water to 
 run out of it. Thus every thing is brought into its first condition ; and 
 when the attendant sees no more water come out at N, he shuts the cocks 
 N and M, and opens the cock I, and the operation is repeated. 
 
 There is a very surprising appearance in the working of this engine. 
 When the efflux at Z has stopped, if the cock Q be opened, the water and 
 air rush out together with prodigious violence, and the drops of water are 
 changed into hail or lumps of ice. It is a sight usually shown to strangers, 
 who are desired to hold their hats to receive the blasts of air : the ice comes 
 out with such violence as frequently to pierce the liat like a pistol bullet, 
 This rapid congelation is a remarkable instance of the general fact, that air 
 by suddenly expanding generates cold, its capacity for heat being increased. 
 
 Tlic above account of the procedure in working this engine shows that 
 the efflux both at Z and N becomes very slow near the end. It is found 
 convenient theiefore not to wait for the complete discharges, but to turn 
 
AND MACHINIST. 
 
 235 
 
 the cocks when about 30 cubic feet of water have been discharged at Z ; 
 more work is done in this way. A gentleman of great accuracy and know- 
 ledge of these subjects took the trouble of noticing particularly the per- 
 formance of the machine. He observed that each stroke, as it may be 
 called, took up about three minutes and one-eighth ; and that 32 cubic feet 
 of water were discharged at Z, and 66 were expended at N. Tire expense 
 therefore is 66 feet of water falling 136 feet, and the performance is 
 32 raised 96, and they are in the proportion of 66 x 136 to 32 x 96, or of 
 1 to 0,3422, or nearly as 3 to 1. This is superior to the performance of the 
 most perfect undershot mill, even when all friction and irregular obstructions 
 are neglected ; and is not much inferior to any overshot pump-mill that 
 has yet been erected. When we reflect on the great obstructions which 
 water meets with in its passage through long pipes, we may be assured, 
 that, by doubling the size of the feeder and discharger, the performance of 
 the machine will be greatly improved ; we do not hesitate to say, that it 
 would be increased one-third : it is true that it will expend more water ; 
 but this will not be nearly in the same proportion, for most of the deficiency 
 of the machine arises from the needless velocity of tire first efflux at Z. 
 The discharging pipe ought to be 110 feet high, and not give sensibly less 
 water. Then it must be considered how inferior in original expense this 
 simple machine must be to a mill of any kind which would raise 10 cubic 
 feet 96 feet high in a minute; and how small the repairs on it need be, 
 when compared with a mill. And, lastly, let it be noticed, that such a 
 machine can be used where no mill whatever can be put in motion. A 
 small stream of water, which would not move any kind of wheel, will here 
 raise one-third of its own quantity to the same heigiit, working as fast as it 
 is supplied. 
 
 For these reasons, the Hungarian machine eminently 
 deserres the attention of mathematicians and engineers, to 
 bring it to its utmost perfection, and into general use. 
 There are situations where this kind of machine may be very 
 useful. Thus, where the tide rises 17 feet, it may be used 
 for compressing air to seven-eighths of its bulk ; and a pipe 
 leading from a very large vessel inverted in it may be used 
 for raising the water from a vessel of one-eighth of its 
 capacity 1/ feet high ; or if this vessel has only one-tenth of 
 the capacity of the large one set in the tide-wa}^, two pipes 
 may be led from it, one into the small vessel, and the other 
 into an equal vessel 16 feet higher, which receives the water 
 from the first. Thus one-sixteenth of the water may be raised 
 34 feet, and a smaller quantity to a still greater height ; and 
 this with a kind of power that can hardly be applied any 
 other way. Machines of this kind are described by Schottus, 
 bturmius, Leupold, and other old writers ; and they should 
 not be forgotten, because opportunities may olfer of making 
 them highly beneficial. 
 
 9. Mr. John Wliitley Boswell has devised an apparatus 
 which when attached to such a machine as that at Chemnitz 
 will enable it to work itself without attendance. The 
 
THE OPERATIVE MECHANIC 
 
 236 
 
 description of this will be presented to the reader in Mr Bos- 
 well’s own words. 
 
 Fig. 213. A is the reservoir, or upper level of water. 
 
 B, a chamber made of sufficient strength to bear the internal pressure 
 of a column of water the height of A above it, multiplied by its own base. 
 
 C, a chamber of the same strength as B, but of a smaller size ; it is placed 
 at the bottom of the pit from which the water is to be raised, and under the 
 level of the water. 
 
 These chambers would be stronger with the same materials, if of a 
 globular or cylindrical form ; but the square shape is used in the drawing 
 merely for the facility of representing the position of the parts. 
 
 D, a pipe from the reservoir A which passes through the top of B and 
 ends near its bottom, to convey water from A to B. 
 
 E, a pipe from the top of B to the top of C, to convey air from B to C. 
 
 F, a pipe from the bottom of C to the level of the ground at the top of 
 the pit, to carry off the water from the pit. 
 
 G, a pipe from the bottom of B to carry off the water from it. 
 
 H, a vessel to contain the water used in working the cocks; it is 
 only placed on the top of B to save the construction of a stand on purpose 
 for it. 
 
 I, a cock, or movable valve, (worked by the lever there represented,) in 
 the large pipe D. 
 
 K, a stop-cock in the small pipe which conveys water from D to H. Its 
 use is to make the engine work faster or slower, by letting water more or 
 less quick into II ; or to stop it altogether from working when required. 
 
 L, a movable valve, or cock in the small pipe L K. The lever which 
 works it is connected by a strong wire with the lever which works I, 
 and is balanced by a weight at its opposite extremity, sufficient to open 
 both these cocks and shut N, when not prevented by a counter weight, 
 
 N, a cock in the pipe G to open and shut it as wanted. 
 
 O, a self-moving valve in the pipe F, wdrich permits the water to pass 
 upwards, but prevents its return. 
 
 P, a self-moving valve at the bottom of C, which permits the water to 
 pass into C, but prevents any from passing out of it; it is furnished with a 
 grating, to prevent dirt getting in. 
 
 R, a vessel suspended from the levers of I and L, capable of containing 
 a weight of water sufficient to shut them. 
 
 S, a vessel suspended from the lever of N : it must contain water enough 
 by its weight to open N : it is connected by a chain to 11, to keep it down 
 as long as N is open.- 
 
 T, a syphon passing from the bottom of H, near its upper edge, and 
 down again to the mouth of R. 
 
 V, a self-moving valve of a sufficient levity to rise, when the water in B 
 comes up to it, and close the pipe E ; into which no water would else pass 
 from B. A ball-cock, such as used in common water cisterns, would do 
 here. 
 
 X, a syphon from the bottom of R rising within an inch of its top, and 
 passing down again to the mouth of S. 
 
 Y, a small pipe at the bottom of S ; this may have a stop-cock to regulate 
 it, whicli, when stopped, will also stop the engine. 
 
 The mode of this engine’s working is as follows : suppose the vessels 
 V, II, R, and S empty of water, and the cocks K and Y open, and the 
 vessel C full of water. The weight on. the lever of L will then open the 
 cocks L and I, on which the water from A will flow into B and li. As 
 
AND MACHINIST. 
 
 237 
 
 ihe water rises in B, it will force the air through E into C, which strongly 
 pressing on the water in C, will force it up through the pipe F, till the 
 water in B rises to the level of V and closes it, at which time H will be full 
 of water, (the quantity flowing in being so regulated by the cock K,) and 
 the water will flow from it through the syphon T into the vessel R, which 
 as it fills shuts the cock I and L, and prevents any more water coming into 
 B and H. When R is full, the water flows through its syphon X, which 
 fills S, and by it opens N, which empties B of water, and keeps N open as 
 long as there is any water in H. 
 
 When H is empty, B will be so too, (being so regulated by the cock K,) 
 on which, in a moment or two, R and S will also be empty, which will 
 cause the cocks I and L to open, and all things will be again in the state 
 first supposed, for a repetition of the operations described. 
 
 To stop the engine, the cocks at K and Y should be shut, while S is full 
 of water. To set it working, they should be open; and this is all the 
 attendance it will require. As no one but an engineer should attempt to 
 construct such an engine as this, it was useless to represent the manner of 
 connecting the pipes by flaches or otherwise, or the proper methods of 
 fastening and closing thp parts, which are all well known to such as have 
 made this art their study. 
 
 In No. 5, of the New Series of Nicholson's Journal, Mr. 
 Boswell has made some further improvements in the applica- 
 tion of the Hungarian machine. 
 
 10. The spiral pump is a very curious hydraulic engine, 
 which operates on nearly the same principle as the Hungarian 
 machine. The first engine of this kind, of which we have 
 seen any account, was invented and erected by H. Andreas 
 Wirtz, a tinplate-worker of Zurich, at a dye-house in Limmat, 
 in the vicinity of that city. It consists of a hollow cylinder, 
 like a very large grindstone, turning on a horizontal axis, and 
 partly plunged in a cistern of water. The axis is hollow at 
 one end, and communicates with a vertical pipe. This cylin- 
 der or drum is formed into a spiral canal, by a plate coiled 
 up within it like the main spring of a watch in its box; only 
 tlie spires at a distance from each other, so as to form a 
 conduit for the water of uniform width. This spiral partition 
 is w’ell joined to the two ends of the cylinder, and no water 
 escapes between them. T’he outermost turn of the spiral 
 begins to widen about three-fourths of a circumference from 
 the end, and this gradual enlargement eontinues nearly a 
 semicircle, this part being called the horn : it then widens 
 suddenly, forming a scoop or shovel. The cylinder is so 
 supported that this shovel may, in the course of a rotation, 
 dip several inehes into the water. As the cylinder turns 
 upon its axis, the scoop dips and takes up a certain quantity 
 of water before it emerges again. This quantity is sufficient 
 to fill the horn ; and this again is nearly equal in capacity to 
 the outermost uniform spiral round. 
 
THE OPERATIVE MECHANIC 
 
 238 
 
 After tlie scoop is einergedj the water passes along the 
 spiral by the, motion of it round the axis, and drives the air 
 before it into the rising pipe, where it escapes. In the mean 
 time, air comes into the mouth of the scoop ; and w^hen the 
 scoop again dips into the water, it again takes in some of 
 that fluid. Thus there becomes a part filled with water, and 
 a part filled with air. Continuing this motion, a second round 
 of water will be received, and another of air. The water in 
 any turn of the spiral will have its two ends on a level; and 
 the air between the successive columns of water will be in its 
 natural state ; for since the passage into the rising pipe or 
 main is open, there is nothing to force the water and air into 
 any other position. But since the spires gradually diminish 
 in their length, it- is plain that the column of water will 
 gradually occupy more and more of the circumference of 
 each. At last it will occupy a complete turn of some spire 
 that is near the centre ; and when sent further in by the 
 continuance of the motion, some of it M^ill run back over the 
 top of the succeeding spire. Thus it will run over into the 
 right-hand side of the third spire, and consequently will 
 push the water of this spire backwai*ds, and raise its other 
 end, so that it will likewise run over backwards before the 
 next rotation be completed. At length this change of dis- 
 position will reach the outermost spire, and some water will 
 run over into the horn and scoop, and finally into the cistern. 
 
 But as soon as water gets into the rising pipe, and rises a 
 little into it, it stops the escape of the air when the next 
 scoop of w^ater is taken in. Hence there are then two columns 
 of water acting against each other by hydrostatic pressure, 
 and the intervening column of air: they must compress the 
 air between them, and the water and air columns will now 
 be unequal : this will have a general tendency to keep the 
 whole water back, and cause it to be higher on the left or 
 rising side of each spire than on the right or descending 
 side ; the excess of height being just such as produces the com- 
 pression of the air between that and the preceding column 
 of water. This will go on increasing as the water mounts 
 in the rising pipe ; for the air next to the rising pipe is com- 
 pressed at its inner eud with the weight of the whole column 
 in the main: and it must be as much compressed at its 
 outer end, w'hich must be done by the water column without 
 it; and this column exerts this pressure partly by reason 
 that its outer end is higher than its inner end, and partly by 
 the transmission of the pressure on its outer end by air, 
 which is similarly compressed from without. Thus it will 
 
A^D MACHINIST. 
 
 239 
 
 liappen that each column of water being higher at its outer 
 than at its inner end, compresses the air on the water 
 column beyond or within it, which transmits this pressure to 
 the air beyond ?V, adding to it the pressure arising from its 
 own want of level at the ends. Consequently, the greatest 
 compression, viz. that of the air next the main, is produced 
 by the sum of all the transmitted pressures ; and these are 
 the sum of all the differences between the elevations of the 
 inner ends of the water columns above their outer ends : and 
 the height to wdiich the neater will rise in the main will be 
 just equal to this sum. 
 
 Suppose the left-hand spaces of each spire to be filled with water, and 
 the right-hand spaces filled with air, as is shown, in regard to one spire, 
 in fig. 214. There is a certain gradation of compression which will keep 
 things in this position : for the spaces manifestly decrease in arithmetical 
 progression ; and so do the hydrostatic heights and pressures ; if, therefore, 
 the air be dense in the same progression all will be in hydrostatical equili- 
 brium. Now this may obviously be produced by the mere motion of the 
 machine ; for since the density and compression in each air column is 
 supposed inversely as the magnitude of the column, the quantity of air is 
 the same in all ; therefore the column first taken in will pass gradually 
 inwards, and the increasing compression will cause it to occupy precisely 
 the whole right-hand of every spire. The gradual diminution of the water 
 columns will be produced, during the motion, by the water running over 
 backwards at the top from spire to spire, and ultimately coming out by the 
 scoop. Since the hydrostatic height of each water column is now the 
 greatest possible, vix. the diameter of the spire, it is evident that this dis- 
 position of the air and water will raise the w^ater to the greatest height. 
 This disposition may be obtained thus : let C B be a vertical radius of the 
 wheel, C being the centre, and B the highest point [the figure may easily be 
 drawn] upon C B, take C L to C B, as the density of the external air to its 
 density in the last column next the rising pipe or main ; that is, make C L 
 to C B as 34 feet (the height of the column of water w hich balances the 
 pressure of the atmosphere) to the sura of 34 feet, and the height of the 
 rising pipe : then divide B L into such a number of turns that the sum of 
 their equal diameters shall be equal to the height of the main; lastly, bring 
 a pipe straight from L to the centre C. Such is the construction of the 
 spiral pump, as originally invented by Wirtz : it certainly indicates very 
 considerable mechanical knowledge and sagacity. 
 
 But when the main is very high this construction will require either an 
 enormous diameter of the drum, or many turns of a very narrow pipe. In 
 such cases it will be much better to make the spiral in the form of a cork- 
 screw, than of this flat form like a watch-spring. The pipe Vvhich forms 
 the spiral may be wrapped round the frustnim of a cone, whose greatest 
 diameter is to the least (which is next to the rising pipe) in the proportion 
 just assigned to C B and C L. By this construction the water will so 
 stand in every round as to have its upper and lower surfaces tangents to 
 the top and bottom of the spiral, and the water columns will occupy the 
 whole ascending side of the machine wdiile the air occupies the descending 
 side. This form is far preferable to the flat form : it will allow us to 
 employ many turns of a large pipe, and therefore produce a great elevation 
 of a large quantity of water. 
 
THE OPERATIVE MECHANIC 
 
 240 
 
 Tiie same thing will be still better accomplished by wrapping the pipe on 
 a cylinder, and making it gradually tapering to the end, in such a manner 
 that the contents of each spire may be the same as when it is wrapped 
 round the cone. It will raise the water to a greater height (though certainly 
 with an increase of the impelling power) by the same number of spires, 
 because the vertical or pressing height of each column is greater. 
 
 In the preceding description of this machine, that construction has been 
 chosen which made its principle and manner of working most evident, 
 namely, that which contained the same material quantity of air in each 
 turn of the spiral, more and more compressed as it approaches to the rising 
 pipe. But this is not the best construction : for we see that in order to raise 
 water to the height of a column of 34 feet, the air in the last spire is com- 
 pressed into half its space ; and the quantity of water delivered into the 
 main at each turn is but half what was received into the first spire, the rest 
 flowing back from spire to spire, and being discharged at the spout. 
 
 But the construction may be such that the quantity of water in each 
 spire may be the same that was received into the first ; by which means a 
 greater quantity (double in the instance now given) will be delivered into 
 the main, and raised to the same altitude by very nearly the same force. 
 This may be done by another proportion of the capacity of the spires; 
 either by a change of their calibre, or of the diameters of the solid on which 
 they are folded. Suppose the bore to be uniform throughout, the diameters 
 must so vary that the constant column of water and the column of air, com- 
 pressed to the proper degree, may occupy the whole circumference. Let 
 A be the column of water which balances the pressure, and H the height to 
 which the water is to be raised. Let A be to A + H as 1 to m. Then it 
 is plain that m will represent the density of the air in the last spire, if its 
 natural density be 1, because it is pressed by the column A + H \vhile the 
 common air is pressed by A. Let 1 represent the constant water column, 
 and consequently it will be nearly equal to the air column in the first spire : 
 
 then the whole circumference of the last spire must be 1 + — , in order to 
 
 ^ m 
 
 hold the water 1 , and to compress the air into the space — or , xhe 
 
 circumference of the first spire is 1 + 1 or 2 ; and if D and d be the dia- 
 meters of the first and last spires, we have 2:1 + — : :T) : d. or 2 m : m 
 
 m ’ 
 
 + 1 : : D ; d If, therefore, a pipe of uniform bore be wrapped round a 
 conic frustrum, of which D and d are the end diameters, the spirals will be 
 very nearly such as will answer the purpose'. It will not be quite exact, 
 for the intermediate spirals will be rather too large : the conoidal frustrum 
 should in strictness be formed by the revolution of a logarithmic curve. 
 With such a spiral the full quantity of water which was confined in the 
 first spire will find room in the last, and will be sent into the main at every 
 rotation. This is a very great advantage, especially when the water is to be 
 much raised. The saving of power by this change of construction is always 
 proportional to the greatest compression of the air. 
 
 The chief difficulty in any of these forms is in determining the form 
 and position of the horn and the scoop ; yet on this the performance of the 
 machine greatly depends. The following instructions will render this 
 tolerably easy. Let A B E O (fig. 214) represent the first or outermost spire, 
 of which the axis is C. Suppose the machine immerged up to the axis in 
 the water whose surface is V V' : it has been seen that it is most effective 
 when the surfaces K B and O w of the water columns are distant from each 
 
M1T]D)]IL^FX,1C 
 
 lYotn Z14 to ZZO 
 
 NecU & Swckl^ sc 3SZ 3irmi2 
 
AND MACHINIST. 
 
 241 
 
 Other the whole diameter B O of the spire. Let therefore tlie pipe be first 
 conceived of eqiral calibre to the very mouth E e, which we suppose to be 
 just about to dip into the water : the surface O n is kept there in opposition 
 to the pressure of the water column B AO, by the compressed air contained 
 in the quadrant O E, and in the quadrant which lies behind E B : and this 
 compression is supported by the columns behind, between this spire and the 
 rising pipe. But the air in the outermost quadrant E B is in its natural 
 state, because it as yet communicates with the external air. When, how- 
 ever, the mouth E e has come round to A, it will not have the water- 
 standing in it in the same manner, leaving the half space B E O filled with 
 compressed air; for it took in and confined only what filled the quadrant 
 B E. It is obvious, therefore, that the quadrant B E must be so shaped 
 as to take in and confine a much greater quantity of air ; so that when it 
 has come to A, the space BED may contain air sufficiently dense to sup- 
 port the column A O. But this is not enough : for when the wide mouth 
 now at A a' rises up to the top, the surface of the water in it rises also, 
 because the part A O o a' is more capacious than the part of uniform bore 
 O E e 0 that succeeds it, and that cannot contain all the w^ater which it 
 previously held. Since then the water in the spire rises above A, it wall 
 press the water back from O n to some other position m n', and the pressing 
 height of the water column will be diminished by this rising on the other 
 side of O. Hence it will appear that the horn must begin to widen, not 
 from B, but from A, and must occupy the whole semicircle ABE; while 
 its capacity must be to the capacity of the opposite side of uniform bore as 
 the sum of B O and the height of a column of water which balances the 
 atmosphere to the height of that column : for then the air which filled it 
 when of the common density will fill the uniform side B E O, when com- 
 pressed so as to balance the vertical column B O. But even this is not 
 sufficient: for it has not taken w'ater enough. When it dipped into the 
 cistern at E it carried air down with it, and the pressure of the water in the 
 cistern caused that fluid to rise into it a little way; and some water must 
 have come over at B fi-om the other side, which was drawing narrow^er. 
 When, therefore, the horn is in the position EGA it is not full of water: 
 consequently, when it comes into the situation O A B it cannot be full, nor 
 can it balance the air on the opposite side. Hence some will come out 
 at O, and rise up through the water. The horn must therefore extend at 
 least from O to B, or occupy half the circumference ; and it must contain at 
 least twice as much water as would fill the side BEG. Nay, if it be 
 much larger, there may be no disadvantage ; because the surplus of air 
 which it takes in at E will be discharged as the end E of the horn rises 
 from O to B, and it will leave the precise quantity that is wanted. The 
 overplus water will be discharged as the horn comes round to dip again 
 into the cistern. 
 
 We must also secure the proper quantity of water. When the machine 
 is so much immersed as to be up to its axis in water, the capacity which 
 thus secures the proper quantity of air will also take in the proper quantity 
 of water. But it may be erected so as that the spirals shall not even reach 
 the water : and in this ease it will answer the purpose if a scoop or shovel 
 be joined to the horn, and so formed as to take in at least as much water as 
 will fill the horn. This is all that is wanted in the beginning of the motion 
 along the spiral, and more than is necessary when the water has advanced 
 to the succeeding spire ; but the overplus is discharged in the way just 
 mentioned. The scoop, it should be observed, must be very open on the 
 side next the axis, that it may not confine the air as it enters the water ; for 
 this would hinder it from receiving enough of that fluid. 
 
 R 
 
242 
 
 THE OPERATIVE MECHANIC 
 
 11. Desaguiiers describes^ in the second volume of his 
 Experimental Philosophy, a very simple contrivance to raise 
 water, which is this : to one end of a rope is fixed a large 
 bucket, having a valve at its bottom, opening upwards ; to 
 the other end is fastened a square frame, and the cord is 
 made to pass over two pulleys, each of about 15 inches 
 diameter, (and fixed in a horizontal plane,) in such a manner 
 that as the bucket descends the frame ascends with equal 
 velocity, and vice versa. The frame is made to run freely 
 upon four vertical iron guide-rods passing through holes at its 
 four corners ; and when the bucket is filling with water at the 
 well, the frame stands at the horizontal plane to which the 
 water is to be raised ; when the bucket is full, a man steps 
 upon the frame ; (his weight, together with that of the frame, 
 exceeding the weight of the vessel and its contained water ;) 
 this gives an ascending motion to the bucket, and causes the 
 valve in its bottom to close. When the bucket is raised to 
 the proper height, a hook fixed there catches into a hasp at the 
 side of the bucket, turns it over, and causes it to empty its 
 water into a trough which conveys it where it is required : at 
 this time the man and the descending-frame have arrived at a 
 platform which prevents their further descent, where the 
 man remains till he finds the bucket above is empty; when 
 he steps from the frame, and runs up a flight of stairs to 
 the place from which he descended : the bucket, in the mean 
 while, being somewhat heavier than the frame, descends to the 
 water, and raises the frame to its original position. Thustlie 
 work is continued, the man being at rest during his descent, 
 and labouring in the ascent. 
 
 Desaguiiers employed in this kind of work a “ tavern draiver,'^ who 
 weighed 160 lbs., whom he desired to go up and down forty steps of 6§ 
 inches each (in all about 22 feet) at the same rate he would go up and down 
 all day. He went up and down twice in a minute ; so that, allowing the 
 bucket with a quarter of a hogshead in it to weigh 140 lbs., he ia able to 
 raise it up through 22 feet twice in a minute : this Desaguiiers estimates 
 as equivalent to a whole hogshead raised 11 feet in a minute, and rather 
 exceeds what he has assigned as a maximum of human exertion. 
 
 This machine is in many cases not only the most simple, but the host 
 that can be devised ; yet it is one that, without due precautions, is likely to 
 be a very bad one. The frame on which the man steps must be brought up 
 to its place again by a preponderancy in the machine when unloaded ; it 
 should arrive precisely at the same time with the man ; but it may arrive 
 sooner or later. If sooner, it is of no use, and wastes power in raising a 
 counterpoise which is needlessly heavy, or in fact less water is elevated than 
 the man is able to elevate; if later there is a loss of time. Hence the per- 
 fection of this truly simple machine requires the judicious combination of 
 two maximums, each of which varies in a ratio compounded of two other 
 ratios. It will not be difficult, however, to adjust the proportions of the 
 
AND MACHINIST. 
 
 243 
 
 weight of the bucket and that of the frame: for if B denote the weight of 
 the bucket, F that of the frame, and (p the force necessary to overcome the 
 friction and the inertia of the pulleys, g denoting 32^ feet, t the time 
 occupied in walking up the steps, and « the space ascended or descended, 
 then must B and F be sO adjusted as to satisfy the following equation, 
 viz. ry 0 
 
 s = -I o- #9 
 
 B + F + (l> 2 ^ 
 
 If there be a spring affording but a small quantity of water, or having 
 but a small fall, it is possible by the loss of some of the water to raise the 
 rest to supply a gentleman's seat, or any place where it is wanted ; but in 
 a less quantity than what runs waste, if the place to which the water is to be 
 raised is higher than the spring or reservoir from which the water falls. 
 Schottus -long ago contrived an engine for this purpose: but the first who 
 put such a thing in execution was Gironimo Finugio, at Rome, in 1616 ; 
 and the first in this country was George Gerves, a carpenter, who, in the 
 year 1725, erected an engine called the Multiplying-wheel Bucket-engine, 
 at the seat of Sir John Chester, at Chichley, in Buckinghamshire. This 
 engine was much approved by Sir Isaac Newton, Dr. Desaguliers, and Mr. 
 Beighton, and was certainly very ingenious. The water from a spring- 
 descended in a large bucket hanging by a cord from an axle, while a smaller 
 quantity was raised from the same place by a cord hanging from a wheel on 
 the same axle : a fly and other regulating apparatus were added, to make 
 the engine work itself, which it did for many years without being out of 
 order. As a whole, however, the contrivance is complex ; and we are not 
 aware that any other engines of the same kind have been erected. A 
 description, with a plate, may be seen in Desaguliers' second volume. 
 
 12. Mr. H. Sarjeant, of Whitehaven, contrived a very cheap 
 engine for raising water, for which the Society for the En- 
 couragement of Arts awarded him a silver medal in the year 
 1801. A sketch of this simple invention is given in fig. 215. 
 
 This engine was erected at Irton-hall, which is situated on an ascent of 60 
 or 61 feet perpendicular height : at the foot of this elevation, about 140 
 yards distant from the offices, there runs a small stream of water ; and, in 
 order to procure a constant supply of that necessary fluid, the object was to 
 raise such stream to the house for culinary or domestic uses. With this 
 view, a dam was formed at a short distance above the current, so as to 
 cause a fall of about four feet : the water was then conducted through a 
 wooden trough, into which a piece of leaden pipe, two inches in diameter, 
 was inserted, and part of which is delineated at A, 
 
 Tire stream of this pipe is directed in such a manner as to run into the 
 bucket B, when the latter is elevated ; but, as soon as it begins to descend, 
 the stream passes over it, and flows progressively to supply the wooden 
 trough or well, at the foot of which stands the forcing-pump C, being three 
 inches in diameter. 
 
 D is an iron cylinder attached to the pump-rod, which passes 
 through it: such cylinder is filled with lead, and weighs about 240 
 pounds. This power works the pump, and forces the water to ascend 
 to the house through a pipe one inch in diameter, and which is 420 feet in 
 length. 
 
 At E is fixed a cord, which, when the bucket approaches to within four 
 or five inches of its lowest projection, extends, and opens a valve in the 
 bottom of the vessel through which the water is discharged. 
 
 An engine in a great degree similar to this was erected some years ago 
 
 R 2 
 
244 
 
 THE OPERATIVE MECHANIC 
 
 by the late James SpedJing, Esq. for a lead mine near Keswick, with the 
 addition of a smaller bucket which emptied itself into the larger near the 
 beginning of its descent, without which addition it was found that the 
 beam only acquired a libratory motion, without making a full and effective 
 stroke. 
 
 To answer this purpose in a more simple way, Mr. Sarjeant constructed 
 the small engine in such manner as to finish its stroke (speaking of the 
 bucket end) when the beam comes into a horizontal position, or a little 
 below it. By this means the lever is virtually lengthened in its descent 
 in the proportion of the radius to the cosine, of about thirty degrees, or 
 as seven to six nearly, and consequently its power is increased in an equal 
 proportion. 
 
 It is evident that the opening of the valve might have been effected, per- 
 haps better, by a projecting pin at the bottom; but Mr. S. chose to give an 
 exact description of the engine as it stands. It has now been some years in 
 use, and completely answers the purpose intended. 
 
 The only artificers employed, except the plumber, were a country black- 
 smith and carpenter ; and the whole cost, exclusive of the pump and pipes, 
 did not amount to 51. 
 
 In a letter, dated Whitehaven, April 28, 1801, Mr. Sarjeant observes, 
 that the pump requires about 1 8 gallons of water in the bucket to raise the 
 counter-weight, and make a fresh stroke in the pump ; but it makes three 
 strokes in a minute, and gives about a half-gallon into the cistern at each 
 stroke. He adds, “ I speak of what it did in the driest part of last summer; 
 when it supplied a large family, together with work-people, &c. with water 
 for all purposes, in a situation where none was to be had before, except 
 some bad water from a common pump, which has been since removed. But 
 the above supply being more than sufficient, the machine is occasionally 
 stopped to prevent wear, which is done by merely casting off the string of 
 the bucket-valve. 
 
 13. Mr. Benjamin Dearborn has contrived an hydraulic 
 engine which may be conveniently added to a common pump, 
 and thereby renders it useful in further elevating tvatcr, and 
 particularly in extinguishing fires : the following description 
 of his apparatus is extracted from the Memoirs of the Ama' lean 
 Academy, 
 
 Fig. 216. A, B, C, D, represents a pump, the form of which is similar 
 to that of the pumps commonly employed on sliip-board. 
 
 E, the spout. 
 
 F, a stopper. 
 
 D, d, a plank-cap, that is fitted to the pump, and provided with leather 
 on its lower surface, being secured by the screws a, b : in the centre is a 
 hole, through which the spear of the pump passes, and round which a leather 
 collar is made, as represented at the letter c. 
 
 gy a nut for the screw b. 
 
 fy a square piece of wood that is nailed across one end of the plank- 
 cap, through both which the screw a is introduced : a hole is made 
 through such piece and the cap that communicates with the bore of the 
 pump. 
 
 G, G, a wooden tube, which may be of any requisite length, and consist 
 of any number of joints ; it is made sqirare at the lower extremity, and per- 
 forated for the reception of the cock ; the upper end being made with a nke 
 shoulder. 
 
AND MACHINIST. 
 
 245 
 
 €, a wooden cock that opens or shuts the communication between the 
 pump and the tube, being furnished on the opposite side with a handle and 
 with a lock, in case it should be found necessary. 
 
 h, h, are two ferules, the object of which is to prevent the tube from 
 splitting. 
 
 H, H, braces, each of which ought to be crossed over another, as nearly 
 at right angles as possible. 
 
 2 , iy are irons in form of a staple, which surround the tube, and pass 
 through the braces.; their ends being perforated with holes for fore-locks. 
 
 K, L, M, N, is a head made of five pieces of wood ; k, I, m, n, a square 
 piece, in the lower part of which is a hole for the reception of the extremity 
 of the tube, and which piece rests on the shoulder o, p ; totlie lower end of 
 this fiead is nailed a piece of leather, with a hole in its centre, similar to 
 that made in the wood. Another piece of leather of the same form is 
 placed on the top of the tube, and between both is a circle of thin plate- 
 brass ; the two pieces of leather and the brass being pressed between the 
 lower end of the head and the shoulder of the tube. Their edges are deli- 
 neated at 0 , p. 
 
 K, N, and L, M, are the edges of two pieces of plank, of a similar width 
 with the head, to which they are closely nailed, each being provided with a 
 tenon, that passes through a mortice in the end of the piece O, P : both 
 tenons have holes for a fore-lock at q. 
 
 O, P, a piece of plank of the same width as the sides ; the centre of 
 which is perforated, in order that the tube may pass through ; and in each 
 end of which is a mortice for the reception of the tenons. 
 
 N, M, a cap. 
 
 r, r, are two pieces nailed to the side of the tube ; the lower extremity of 
 each is provided with a truck, with a view to lessen the Iriction of the head 
 in its horizontal revolution. 
 
 qy qy represent fore-locks, the design of which is to fasten down the head, 
 and prevent the water from escaping at the joint o, p. 
 
 Q, R, is a wooden conductor : the extremity marked with the letter Q 
 being solid, while the opposite end, 11, is bored with a small auger. 
 
 s, a bolt that passes through the conductor and head, and being secured 
 on the back with a fore-lock or nut : this bolt is rounded near the head, and 
 square in the middle. 
 
 ty Uy Wy Xy Teprcsents a piece of iron or brass, designed to prevent the head 
 •of the bolt from wearing into the v/ood. 
 
 S, S, are ropes for the direction of the conductor. 
 
 Fig. 217 represents the head without such conductor. 
 
 a, hy Cy dy is a thick brass plate, the centre of which is perforated, so as to 
 admit a passage to impurities, that might otherwise obstruct the conductor : 
 for which purpose a piece of leather is nailed under it to the head. The 
 square hole in the centre is adapted to the size of the bolt, which it prevents 
 from turning. Tlie conductor has a hollow cut round the bolt on the inside, 
 of the same size as the circle of holes in the brass ; round such cavity is 
 nailed, on the face of the conductor, a piece of leather, that plays on the 
 margin of the brass plate when the conductor is in motion. 
 
 In the conclusion of his memoir, Mr. Dearborn observes, that he has 
 raised a tube of 30 feet on his pump; and, though the severity of the season 
 had prevented him from completing it, so that one person only could work 
 at the brake, yet he is enabled to throw water on a contiguous building, the 
 nearest part of which is 37 feet from the pump, and between 30 and 40 
 ,/eet in height. 
 
THE OPERATIVE MECHANIC 
 
 246 
 
 14. Archimedes' Screw, or the Spiral Pump, or, as it is 
 called in Germany, the Water-snail, is a machine for the 
 raising of water, first invented by Archimedes. 
 
 Its structure and use will be understood by the following 
 description of it. 
 
 Fig. 218. A, B, C, D, is a wheel, which is turned round, according to 
 tlie order of the letters, by the fall of water E F, which need not be more 
 than three feet. The axle G of the wheel is elevated so as to make an 
 angle of about 44®, or between 45® and 60®, with the horizon : and on the 
 top of that axle is a wheel H, which turns such another wheel I of the same 
 number of teeth ; the axle K of this last wheel being parallel to the axle G 
 of the two former wheels. The axle G is cut into a double-threaded screw, 
 fig. 219, exactly resembling the screw on the axis of the fly of a common jack, 
 which must be what is called a right-handed screw, like the wood screws, if 
 the first wheel turns in the direction A B C D ; but it must be a left-handed 
 screw, if the stream turns the wheel the contrary way ; and the screw on 
 the axle G must be cut in a contrary way to that on the axle K, because 
 these axles turn in contrary directions. 
 
 These screws must be covered close over with boards, like those of a 
 cylindrical cask ; and then they will be spiral tubes. Or they may be made 
 of tubes of stiff leather, and wrapped round the axles in shallow grooves cut 
 therein, as fig. 220. The lower end of the axle G turns constantly in the 
 stream that turiis the wheel, and the lower ends of the spiral tubes are open 
 unto the water. So that, as the wheel and axle are turned round, the water 
 rises in the spiral tubes, and runs out at Q, through the holes M N, as they 
 come about below the axle. These holes, of which there may be any num- 
 ber, as four or six, in a broad close ring on the top of the axle, into which 
 ring the water is delivered from the upper open ends of the screw tubes, 
 and falls into the open box N. The lower end of the axle K turns on a 
 gudgeon, in the water N ; and the spiral tubes in that axle take up the 
 water from N, and deliver it into another such a box under the top of K ; on 
 which there may be such another wheel as I, to turn a third axle by such a 
 wheel upon it. And in this manner water may be raised to any given 
 height,where there is a stream sufficient for that purpose to act on the broad 
 float-boards of the first wheel. 
 
 15. Another kind of engine, called the Pressure Engine, 
 several of which have been lately erected in different parts of 
 the country, is used for raising water by the pressure and 
 descent of a column enclosed in a pipe. The principle was 
 first adopted in France, in some machinery erected about 
 1731 , and is described by Belidor, in his Arch, Hydraul, lib. 
 iv. ch. 1. But the engine we are now going to describe is the 
 invention of Mr. Trevitheck, who probably was not aware 
 that one of a similar nature had been before attempted. It 
 was erected about thirty years ago at the Druid Copper-mine, 
 in the parish of Illogan, near Truro. 
 
 A section of it is given in Fig. 221 . 
 
 A B represent a pipe six inches in diameter, through which water descends 
 from the head to the place of its delivery to run off by an adit at S, through 
 a fall of 34 fathoms in the whole ; that is to say, in a close pipe down the 
 felopc of a hill 200 fathoms long, with 26 fathoms fall, then perpendicularly 
 
AND MACHINIST. 
 
 247 
 
 six fathoms till it arrives at B, and thence through the engine from B to S 
 tvro fathoms. At the turn B the water enters into a chamber C, the lower 
 part of which terminates in two brass cylinders, four inches in dianrieter ; in 
 which two plugs or pistons of lead, D and E, are capable of moving up 
 and down by their piston-rods, which pass through a close packing above, 
 and are attached to the extremities of a chain leading over and properly 
 attached to the wheel Q, so that it cannot slip. 
 
 The leaden pipes D and E are cast in their places, and have no packing 
 whatever. They move very easily ; and if at any time they should become 
 loose, they may be spread out by a few blows with a proper instrument, 
 without taking them out of their place. On the sides of the two brass 
 cylinders in which D and E move, there are square holes communicating 
 towards F and G, which is a horizontal trunk or square pipe, four inches 
 wide and three inches deep. All the other pipes G, G, and R, are six 
 inches in diameter, except the principal cylinder wherein the piston H moves ; 
 and this cylinder is ten inches in diameter, and admits a nine-foot stroke, 
 though it is here delineated as if the stroke were only a three-foot. 
 
 The piston-rod works through a stuffing-box above, and is attached to 
 M N, which is the pit-rod, or a perpendicular piece divided into two, so as 
 to allow its alternate motion up and down, and leave a space between, 
 without touching the fixed apparatus or great cylinder. The pit-rod is 
 prolonged down into the mine, where it is employed to work the pumps ; 
 or if the engine were applied to mill-work, or any other use, this rod would 
 form the communication of the first mover. 
 
 K L is a tumbler, or turabling-bob, capable of being moved on the gud- 
 geon V, from its present position to another, in which the weight L shall 
 hang over the same inclination on the opposite side of the perpendicular, 
 and consequently the end K will then be as much elevated as it is now 
 depressed. 
 
 The pipe R S has its lower end immersed in a cistern, by which means it 
 delivers its water without the possibility of the external air introducing 
 itself ; so that it constitutes a torrieellian column, or water barometer, and 
 renders the whole column from A to S efiectual : as we shall see in our view 
 of the operation. 
 
 Let us suppose the lower bar K V of the tumbler to be horizontal, and 
 the rod P O so situated, as that the plugs or leaden pistons D and E shall 
 lie opposite to each other, and stop the water-ways G and F. In this state 
 of the engine, though each of these pistons is pressed by a force equivalent 
 to more than 1000 pounds, they will remain motionless, because these 
 actions being contrary to each other, they are constantly in equilibrio. The 
 great piston H being here shown as at the bottom of its cylinder, the tum- 
 bler is to be thrown by hand into the position here delineated. Its action 
 upon O P, and consequently upon the wheel Q, draws up the plug D, and 
 depresses E, so that the water-way G becomes open from A B, and that of 
 F to tlie pipe R : the water consequently descends from A to C ; thence to 
 G G G, until it acts beneath the piston H. Tliis pressure raises the piston, 
 and if there be any water above the piston, it causes it to rise and pass 
 through F into R. During the rise of the piston (which carries the pit-rod 
 M N along with it) a sliding block of wood I, fixed to this rod, is brought 
 into contact with the tail K of the tumbler, and raises it to the horizontal 
 position, beyond which it oversets by the acquired motion of the wheel L. 
 
 The mere rise of the piston, if there v^^ere no additional motion in the 
 tumbler, would only bring the two plugs D and E to the position of rest, 
 namely, to close G and F, and then the engine would stop ; but the fall of 
 the tumbler carries tire plug D downwards quite clear of the hole F, and 
 
248 
 
 THE OPERATIVE MECHANIC 
 
 the other plug E upwards, quite clear of the hole G. These motions require 
 no consumption of power, because the plugs are in equilibrio, as was just 
 observed. 
 
 In this new situation the column A B no longer communicates with G, 
 but acts through F upon the.upper part of the piston H, and depresses it ; 
 while the contents of the great cylinder beneath that piston are driven out 
 through G G G, and pass through the opening at E into R. It may be 
 observed, that the column which acts against the piston is assisted by the 
 pressure of the atmosphere, rendered active by the column of water hanging 
 in R, to which that assisting pressure is equivalent, as has already been 
 noticed. 
 
 When the piston has descended through a certain length, the slide or 
 block at T, upon the pit-rod, applies against the tail K of the tumbler, 
 which it depresses, and again “Oversets ; producing once more the position 
 of ihe plugs D E, here delineated, and the consequent ascent of the great 
 piston H, as before described. The ascent produces its former effect on the 
 tumbler and plugs ; and in this manner it is evident that the alterations will 
 go on without limit, or until the manager shall think fit to place the tumbler 
 and plugs D E in the positions of rest ; namely, so as to stop the passages 
 F and G. 
 
 The length of the stroke may be varied by altering the positions of the 
 pieces T and I, which will shorten the stroke the nearer they are together ; 
 as in that case they will sooner alternate upon the tail K. 
 
 As the sudden stoppage of the descent of the column A B, at the instant 
 when the two plugs were both in the water-way, might jar and shake the 
 apparatus, those plugs are made half an inch shorter than, the depth of the 
 side holes ; so that in that case the water can escape directly through both 
 the small cylinders to R. This gives a moment of time for the generation 
 of the contrary motion in the piston and the water in G G G, and greatly 
 deadens the concussion which might else be produced. 
 
 Some former attempts to make pressure- engines upon the 
 principle of the steam-engine have failed ; because water, not 
 being elastic, could not be made to carry the piston onwards 
 a little, so as completely to shut one set of valves and open 
 another. In the present judicious construction, the tumbler 
 performs the office of the expansive force of steam at the end 
 of the stroke. 
 
 Mr. Boswell suggests, as a considerable improvement, that 
 the action of this engine should be made elastic by the addi- 
 tion of an air-chamber, on the same principle as that used in 
 fire-engines ; this, he thinks, might be best effected by making 
 the piston hollow, with a small orifice in the bottom, and of 
 a larger size, to serve for this purpose, as the spring of the air 
 would then act both on the upward and downward pressure of 
 the water. 
 
 There are many other ingenious hydraulic engines of great 
 utility, which the limits of our work will not permit us to 
 describe ; in order, therefore, to supply the deficiency, we 
 shall add a catalbgue of the most important writings on this 
 kind of engine. 
 
JPUMS 
 
 From 2ntoZ24- 
 
 Flzs 
 
 222 
 
 222 
 
 &StoJdar s^c36zSfrond. 
 
AND MACHINIST. 249 
 
 Descriptio Machinse Hydraulicae curiosae constructse Joh. Geor. Faudieri. 
 Venet. 1607. 
 
 Nouvelle Invention de lever I’Eau plus haul que la Source, avec quelque 
 Machines Mouvantes par le Moyen de FEau, &c. par Isaac de Caus, 1657. 
 
 Josephi Gregorii a Monte Sacr. Principia Physico-mechanica diversarum 
 Machinarum sen Instrumentorum Pneunriatices ac Hydraulices. Venet. 1664. 
 
 Nouvelle Machine Hydraulique, par Francini. Journ. des S^av. 1669. 
 
 [An account of this machine is likewise given in the Architecture Hy- 
 draulique of Belidor, tom. 2. and in the 2d vol. of Desaguliers’ Experi- 
 mental Philosophy: in both which performances many other hydraulic 
 machines are described.] 
 
 An Undertaking for raising Water, by Sir Samuel Moreland. Phil. Trans. 
 1674, No. 102. 
 
 An Hydraulic Engine, by Phil. Trans. 1675, No. 128. 
 
 A cheap Pump, by Mr. Conyers. Phil. Trans. 1677, No. 136. 
 
 M. de Ilautefeuille, Reflexions sur quelques Machines a Clever les Eaux, 
 avec sa Description d’une nouvelle Pompe, sans Frottement et sans Piston, 
 &c. 1682. 
 
 Elevation des Eaux par toute sorte de Machines, r^duite a la mesure, au 
 poids, a la balance, par le moyen d’un nouveau piston et corps de pompe, et 
 d’un nouveau mouvement cyclo-elliptique, et rejetant I’usage de toute sorte 
 de manivelles ordinaires, par le Chevalier Morland. 1685. 
 
 A new Way of raising Water, enigmatically proposed, by Dr. Papin. 
 Phil. Trans. 1685, No. 173. The solutions by Dr. Vincent and Mr. R. A. 
 in No. 177. 
 
 M. du Torax, . Nouvelles Machines pour ^puiser I’Eau des Fondations, 
 / qui, quoique trhs simples, font un effet surprenant. 1695. Journ. des Spav. 
 1695, p. 293. 
 
 An Engine for raising Water by the help of Fire, by Mr. Tho. Savery. 
 Phil. Trans. 1699, No. 253. 
 
 D. Papin, Nouvelle Manihre pour lever I’Eau par la Force du Feu : 
 a Cassel. 1707. 
 
 M^moire pour la Construction d’une Pompe qui fournit continuellement 
 de I’Eau dans le Reservoir, par M. de la Hire, Mem. Acad. Sci. Paris. 1716. 
 
 Description d’une Machine pour elever des Eaux, par M. de la Faye, 
 Mem. Acad. Sci. Paris. 1717. 
 
 Joh. Jac. Bruckmann’s und Joh. Heinr. Weber’s Elementar-maschine, 
 Oder universal-mittel bey alien wasser-hebungen. Cassel. 1 720. 
 
 Jacob Leopold, Theatri Machinarum Hydraulicarum. 1724, 1725. 
 
 Joh. Frid. Weidleri Tractatus, de Machinis Hydraulicis toto terrarum 
 orbe maximis Marlyensi et Londinensi, &c. 1727. Vide Act. erudit. 
 Lips. 1728. 
 
 A Description of the Water-works at London-bridge, by H. Beighton, 
 F.R.S. Phil. Trans. 1731, No. 417. 
 
 An Account of a new Engine for raising Water, in which horses or other 
 animals draw without any loss of power (which has never yet been prac- 
 tised ;) and how the strokes of the piston may be made of any length, to 
 prevent the loss of water by the too frequent opening of valves, &c. by 
 Walter Churchman. Phil. Trans. 1734. 
 
 Sur I’Eflet d’une Machine Hydraulique propos^e par M. Segner, par 
 M. Leon. Euler, Mem. Acad. Sci. Berlin. 1750. 
 
 ^ Application de la Machine Hydraulique de M. Segner k toutes sortes 
 d’ouvrages, et de ses avantages sur les autres Machines Hydrauliques, par 
 M. Leon. Euler, Mem. Acad. Sci. Berlin. 1751. 
 
 [M. Segner’s machine is no other than the simple yet truly ingenious 
 
THE OPERATIVE MECHANIC 
 
 250 
 
 contrivance known by tlie name of Barker’s miH, which had been described 
 in the 2d volume of Desaguliers' Philosophy, some years before the German 
 professor made any pretensions to the honour of the invention. The theory 
 of it is likewise treated by John Bernoulli at the end of his Hydraulics.] 
 Recherches sur une nouvelle manihre d clever de I’Eau proposee par 
 M. de Mour, par M. L. Euler, Mem. Acad. Berlin. 1751. 
 
 Discussion particulibre de diverses manibres d’elever de I’Eau par le 
 moyen des Pompes, par M. L. Euler, Mem. Acad. Ber. 1752. 
 
 Maximes pour arranger le plus avantageusement les Machines destinees 
 a blever de VEau par le moyen des Pompes, par M. L. Euler, Mem. Acad. 
 Ber. 1752. 
 
 Reflexions sur les Machines Hydrauliques, par M. le Chevalier D^Arcy, 
 Mem. Acad. Sci. Paris. 1754. 
 
 Memoire sur les Pompes, par M. le Chevalier de Borda, Mem. Acad. 
 Sci. Paris. 1768. 
 
 Dan. Bernoulli Expositio Theoretica singularis Machinae Hydraulicae. 
 Figuri helvetiorum, exstmctse. Nov. Com. Acad. Petrop. 1772. 
 
 Abhandlungen von der Wasserschraube, von D. Scherffer, Priester. Wien. 
 1774. 
 
 Recherches sur les Moyens d’executer sous I’Eau toutes sortes de Travaux 
 Hydrauliques, sans employer aucun Epuisement, par M. Coulumb. 1 779. 
 
 Saemund Magnussen Holm, Efterretning om skye Pumpen. Kiobenhavn. 
 1779. 
 
 Moyen d'augmenter la Vitesse dans le Mouvement de la Vis d’Archimbde 
 sur son Axe, tire des Memoir es Manuscrits de M. Pingeron, sur les Arts 
 utiles et agreables. Journ. d’Agric. Juin, 1780. 
 
 The Theory of the Syphon, plainly and methodically illustrated. 1781. 
 (Richardson.) 
 
 Memoria sopra la nuova Tromba Funiculare Umiliata, dal Can. Carlo 
 Castelli. Milano. 1782. 
 
 Dissertation de M. de Parcieux, sur le moyen d’elever I’Eau par la rota- 
 tion d\me corde verticale sans fin. Amsterdam et Paris, 1792. 
 
 Theorie der Wirzischen Spiral Pumpe, erlautert von Heinr. Nicander. 
 Schwed. Abhandl. 1783. 
 
 Jac. Bernoulli, Essai sur une nouvelle Machine Hydraulique propre a 
 blever de I’Eau, et qu’on peut nommer Machine Pitotienne. Nov. Act. 
 Acad. Petrop. 1786. 
 
 K. Ch. Langsdorf’s Berechnungen fiber die Vortheilhaeftere Benutzung 
 Angelegter Fammelteiche zur Betriebung der Maschinen. Act. Acad. Elect. 
 Mogunt. 1784, 1785. 
 
 Nicander’s Theorie der Spiral Pumpe. 1789. 
 
 Nouvelle Architecture Hydraulique, par M. Prony. 1790, 1796. 
 
 A short Account of the Invention, Theory, and Practice of Fire Machinery; 
 or. Introduction to the Art of making Machines vulgarly called Steam- 
 ihigines, in order to extract water from mines, convey it to towns, and jets- 
 d’eaux in gardens ; to procure water-falls for fulling, hammering, stamping, 
 rolling, and cornr-mills; by W. Blakey. 1793. 
 
 PUMPS. 
 
 1 . The construction of pumps is usually explained by glass 
 models, in which the action both of the pistons and valves 
 may be seen. 
 
 In order to understand the structure and operation of the common pump, 
 let the model D C B L, fig. 222, be placed upright in the vessel of water K, 
 the water being deep enough to rise at least as high as from A to L. The 
 
and machinist. 
 
 251 
 
 valve a on the movable bucket. G, and the valve b on the fixed box H, 
 (which box quite fills the bore of the pipe or barrel at H,) will each lie close 
 by its own weight, upon the hole in the bucket and box, until the engine 
 begins to w'ork. The valves are made of brass, and covered underneath 
 with leather, for closing the hole more exactly; and the bucket G is raised 
 and depressed alternately by the handle E and rod D d, the bucket being 
 supposed at B before the working begins. 
 
 Take hold of the handle E, and thereby draw up the bucket from B to C, 
 which will make room for the air in the pump all the way below the bucket 
 to dilate itself, by which its spring is weakened, and then its force is not 
 equivalent to the weight or pressure of the outward air upon the water in 
 the vessel K ; and therefore, at the first stroke, the outward air will press 
 up the water through the notched foot A, into the lower pipe, as far as e : 
 this will condense the rarefied air in the pipe between e and C to the same 
 state as it was in before ; and then, as its spring within the pipe is equal to 
 the force or pressure of the outward air, the water will rise no higher by the 
 first stroke ; and the valve b, which was raised a little by the dilatation of 
 the air in the pipe, will fall, and stop the hole in the box H ; and the surface 
 of the water will stand at e. Then depress the piston or bucket from C to 
 B, and as the air in the part B cannot get back again through the valve 
 it will (as the bucket descends) raise the valve a, and so make its way 
 through the upper part of the barrel d into the open air. But, upon raising 
 the bucket G a second time, the air between it and the water, in the lower 
 pipe at e, will be again left at liberty to fill a larger space ; and so its spring 
 being again weakened, the pressure of the outward air on the water in the 
 vessel K will force more water up into the lower pipe from e to f; and 
 when the bucket is at its greatest height C, the lower valve b will fall, and 
 stop the hole in the box H as before. At the next stroke of the bucket or 
 piston, the water will rise through the box H towards B, and then the valve 
 b, which was raised by it, will fall when the bucket G is at its greatest 
 height. Upon depressing the bucket again, the water cannot be pushed 
 back through the valve b, which keeps close upon the hole whilst the piston 
 descends. And upon raising the piston again, the outward pressure of the 
 air will force the water up through H, where it will raise the valve, and 
 follow the bucket to C. Upon the next depression of the bucket G, it will go 
 down into the water in the barrel B ; and as the water cannot be driven back 
 through the now close valve Z>, it will raise the valve a as the bucket descends, 
 and will be lifted up by the bucket when it is next raised. And now, the 
 whole space below the bucket being full, the water above it cannot sink 
 when it is depressed ; but upon its depression, the valve a will rise to let 
 the bucket go down ; and when it is quite down, the valve a will fall by its 
 own weight, and stop the hole in the bucket. When the bucket is next 
 raised, all the water above it will be lifted up, and begin to r un off by the 
 pipe F. And thus, by raising and depressing the bucket alternately, there 
 is still more water raised by it ; which getting above the pipe F, into the 
 wide top I, will supply the pipe, and make it run with a continued stream. 
 
 So, at every time the bucket is raised, the valve b rises, and the valve a 
 falls; and at every time the bucket is depressed, the valve b falls, and the 
 valve a rises. 
 
 As it is the pressure of the air or atmosphere which causes the water to rise, 
 and follow the piston or bucket G as it is drawn up ; and since a column of water 
 32 feet high is of equal weight with as thick a column of the atmosphere, 
 from the earth to the very top of the air; therefore the perpendicular height 
 
 the piston or bucket from the surface of the water in the well must always 
 
2o2 
 
 THE OPERATIVE MECHANIC 
 
 be less than 32 feet ; otherwise the water will never get above the bucket. 
 Hut when the height is less, the pressure of the atmosphere will be greater 
 than the weight of the water in the pump, and will therefore raise it above 
 the bucket ; and when the water has once got above the bucket, it may be 
 lifted to any height, if the rod D be made long enough, and a sufficient 
 degree of strength be employed, to raise it with the weight of the water 
 above the bucket without ever lengthening the stroke. 
 
 The force required to work a pump will be as the height to 
 which the water is raised, and as the square of the diameter 
 of the pump-bore in that part where the piston works. So 
 that if two pumps be made of equal heights, and one of them 
 be twice as wide in the bore as the other, the widest will raise 
 four times as much water as the narrowest, and will require 
 therefore four times as much strength to work it. 
 
 The wideness or narrowness of the pump in any other part 
 besides that in which the piston works, does not make the 
 pump either more or less difficult to work, except what differ- 
 ence may arise from the friction of the water in the bore, 
 which is always greater in a narrow bore than in a wide one, 
 because of the great velocity of the water. 
 
 The pump-rod is never raised directly by such a handle as 
 E at the top, but by means of a lever, whose longer arm (at 
 the end of which the power is applied) generally exceeds the 
 length of the shorter arm five or six times, and by that means 
 gives five or six times as much advantage to the power. Upon 
 these principles, it will be easy to find the dimensions of a 
 pump that shall work with a given force, and draw water 
 from any given depth. 
 
 The quantity of water raised by each stroke of the pump- 
 handle is just as much as fills that part of the bore in which 
 the piston works, be the size of the rest of the bore ab(»ve and 
 below the piston what it will. The pressure of the atmo- 
 sphere will raise the water 32 feet in a pipe exhausted of air ; 
 but it is advisable never to have the piston more than 20 or 
 24 feet above the level of the surface of the water in which 
 the lower end of the pump is placed ; and the power required 
 to w'ork the pump will be the same, whether the piston goes 
 down to lie on a level with the surface of the well, or whether 
 it works 30 feet above that surface, because the w^eight of the 
 column of air that the piston lifts is equal to the weight or 
 pressure of the column of water raised by the pressure of the 
 air to the piston. And although the pressure of the air on 
 the surface of the well will not raise or force up the water in 
 the pump-bore more than 32 feet, yet when the piston goes 
 4own into the column so raised, the water gets above it, and 
 
AND MACHINIST. 
 
 253 
 
 may then be raised to any height whatever above the piston, 
 according to the quantity of power applied to the handle of 
 the pump for that purpose. 
 
 Pumps ought to be made so (says Mr. Ferguson) as to work 
 with equal ease in raising the water to any given height above' 
 the surface of the well. And this may be done by duly jjro- 
 portioning the diameter of the bore (in that part where the 
 piston works) to the height the water is to be raised, as that 
 the column of water may be no heavier in a long j)ump than 
 in a short one, or indeed equally heavy in all pumps from the 
 shortest to the longest, on a supposition that the diameter of 
 the bore is the same size from top to bottom ; and whatever 
 size the bore be, above or below that part in which the piston 
 works, the power required to work the pump will be just the 
 same as if the bore was of the same size throughout. 
 
 In order that a man of common strength may raise water 
 by pumps with the same ease, to any height not less than 
 10 feet, or more than 100 feet, above the surface of the well, 
 Mr. Ferguson has calculated the annexed table, in which the 
 diameter of the bore is duly proportioned to the height ; and 
 in these calculations he supposes the pump-handle to be a 
 lever increasing the power five times. 
 
 Heigiit of the 
 
 Diameter of the 
 
 Water discharged i 
 
 pump, in feet, 
 
 
 bore. 
 
 a minute, 
 
 above tlie surface 
 of the well. 
 
 100 parts of 
 Inches, an inch. 
 
 in wine measure. 
 Gallons. Tints. 
 
 10 
 
 6 
 
 •93 
 
 81 
 
 6 
 
 15 
 
 5 
 
 •6G 
 
 54 
 
 4 
 
 20 
 
 4 
 
 •90 
 
 40* 
 
 7 
 
 25 
 
 4 
 
 •38 
 
 32 
 
 6 
 
 30 
 
 4 
 
 •00 
 
 27 
 
 2 
 
 35 
 
 3 
 
 •70 
 
 23 
 
 3 
 
 40 
 
 3 
 
 •46 
 
 20 
 
 3 
 
 45 
 
 3 
 
 •27 
 
 18 
 
 1 
 
 50 
 
 3 
 
 •10 
 
 16 
 
 3 
 
 55 
 
 2 
 
 •95 
 
 14 
 
 7 
 
 60 
 
 2 
 
 •84 
 
 13 
 
 5 
 
 65 
 
 2 
 
 •72 
 
 12 
 
 4 
 
 70 
 
 2 
 
 •62 
 
 11 
 
 5 
 
 75 
 
 2 
 
 •53 
 
 10 
 
 7 
 
 80 
 
 2 
 
 •45 
 
 10 
 
 2 
 
 85 
 
 2 
 
 •38 
 
 9 
 
 5 
 
 90 
 
 2 
 
 •31 
 
 19 
 
 1 
 
 95 
 
 2 
 
 •25 
 
 8 
 
 5 
 
 100 
 
 2 
 
 •19 
 
 8 
 
 1 
 
 In the first column look for the number of feet the water is 
 to be raised ; then, in the second column, you have the dia- 
 meter of that part of the bore in which the piston or bucket 
 works ; and in the third column, the quantity of water which 
 
254 
 
 THK OPERATIVE MECHANIC 
 
 a man of ordinary strength can raise in a minute by the pump 
 to the given height. 
 
 The quantity of water contained in a pipe of either of those 
 heights in the table, supposing the diameter of the bore to be 
 the same from top to bottom, is 4523*2 cubic inches, or 19*58 
 gallons in wine-measure, as near as the hundredth part of an 
 inch in the diameter of the bore can make it. 
 
 Mr. Ferguson has calculated the following table, by which 
 the quantity and weight of water in a cylindrical bore of any 
 given diameter and perpendicular height may be very readily 
 found. 
 
 Diameter of the cylindrical bore 1 inch. 
 
 Feet liigh. 
 
 Quantity of water, 
 in cubic inches. 
 
 Weight of water, 
 in troy ounces. 
 
 In avoirdupoise ounces. 
 
 1 
 
 9*4247781 
 
 4*9712340 
 
 5*4541539 
 
 2 
 
 18*8495562 
 
 9-9424680 
 
 10*9083078 
 
 3 
 
 28*2743343 
 
 14*9137020 
 
 16*3624617 
 
 4 
 
 37*6991124 
 
 19*8849360 
 
 21*8166156 
 
 5 
 
 47*1238905 
 
 24*8561700 
 
 27*2707695 
 
 6 
 
 56*5486686 
 
 29*8274040 
 
 32*7249234 
 
 7 
 
 65*9734467 
 
 34*7986380 
 
 38*1790773 
 
 8 
 
 75*3982248 
 
 39*7698720 
 
 43*6332312 
 
 9 
 
 84*8230029 
 
 44*7411060 
 
 49*0873851 
 
 For tens of feet high, remove the decimal points one place 
 towards the right hand ; for hundreds of feet, two places ; for 
 thousands, three places ; and so on. Then multiply each 
 sum by the square of the diameter of the given bore, and the 
 products will be the answer. 
 
 Example : 
 
 Qu. What is the quantity and weight of water in an upright 
 pipe 85 feet high, and 10 inches in diameter of bore ? The 
 square of 10 is 100. 
 
 Feet high. 
 
 
 Cubic inches. 
 
 Troy ounces. 
 
 Avoirdupoise ounces. 
 
 80 
 
 
 753* 982248 
 
 397* 698720 
 
 436* 332312 
 
 5 
 
 
 47*1238905 
 
 24*8561700 
 
 27*2707695 
 
 85 
 
 
 801*1061385 
 
 422*5548900 
 
 463*6030815 
 
 Multiply by , 
 
 100 
 
 100 
 
 100 
 
 Answer . . . 
 
 , 80110*6138500 
 
 42255*4890000 
 
 46360* 308150 
 
 Which number (80110'61) of cubic inches being divided by 231, the 
 number of cubic inches in a wine gallon, gives 342*6 for the number of 
 gallons in the pipe ; and 42255*489 troy ounces being divided by 12, gives 
 3521 *29 for the weight of the water in troy pounds ; and, lastly, 46360*3 
 avoirdupoise ounces being divided by 16, gives 2897*5 for the weight in 
 avoirdupoise pounds. 
 
AND MACHINIST. 
 
 255 
 
 The power required to work a pump^ or any other hydraulic 
 engine, must not only be equal to the whole column of water 
 in the pump-bore, but as much superior to it as will overcome 
 all the friction of the working parts of the engine. 
 
 2. In Dr. Gregory’s Mechanics ^ vol. ii. is the following 
 description of a pump, with little friction, which may be con- 
 structed in a variety of ways by any common carpenter, 
 without the assistance of the pump-maker, or plumber, and 
 which will be very effective for raising a great quantity of 
 water to small heights, as in draining marshes, marie pits, 
 quarries, &c., or even for the service of a house. 
 
 ABCD, fig. 223, is a square trunk of carpenter’s work open at both 
 ends, and having a little cistern and spout at top. Near the bottom there 
 is a partition made of board, perforated with a hole E, and covered with a 
 dock, ////represent a long cylindrical bag made of leather or of double 
 canvass, with a fold of thin leather, such as sheep skin, between the canvass 
 bags. This is firmly nailed to the board E with soft leather between. The 
 upper end of this bag is fixed on a round board having a hole and valve F. 
 This board may be turned in the lathe with a groove round its edge, and 
 the bag fastened to it by a cord bound tight round it. The fork of the 
 piston-rod F G is firmly fixed into this board ; the bag is kept distended by 
 a number of wooden hoops or rings of strong wire,//,//,// &c. put into 
 it at a few inches distance from each other. It will be proper to connect 
 these hoops, before putting them in, by three or four cords from top to bottom, 
 which will keep them at their proper distances. Tims will the bag have 
 the form of a barber’s bellow's pow'der-puff. The distance between the 
 hoops should be about twice the breadth of the rim of the wooden ring to 
 which the upper valve and piston-rod are fixed. 
 
 Now let this trunk be immersed in the water. It is evident that if the 
 bag be stretched from the compressed form which its own weight w’ill give 
 it by drawing up the piston-rod, its capacity will be enlarged, the valve F 
 will be shut by its own w'eight, the air in the bag will be rarefied, and the 
 atmosphere will press the water into the bag. When the rod is thrust 
 down again, this water will come out by the valve F, and fill part of the 
 trunk. A repetition of the operation will have a similar eftect ; the trunk 
 will be filled, and the water will at last be discharged by the spout. 
 
 Here is a pump almost divested of friction, and perfectly 
 light. For the leather between the folds of canvass renders 
 the bag impervious both to air and water. And the canvass 
 has very considerable strength. We know', from experience, 
 that a bag of six inches diameter, made of sail-cloth No. 3, 
 with a sheep-skin between, wdll bear a column of 15 feet of 
 W'ater, and six hours work per day for a month without 
 failure, and that the pump is considerably superior in eftect 
 to a common pump of the same dimensions. We must only 
 observe, that the length of the bag must be three times the 
 intended length of the stroke ; so that when the piston-rod is 
 in its highest position, the angles or ridges of the bag may 
 be pretty acute. If the bag be more stretched than this. 
 
256 
 
 THE OPERATIVE MECHANIC 
 
 the force which must be exerted by the labourer becomes 
 much greater tlian the weight of the column of water which 
 he is raising. If the pump be laid aslope^ which is very usual 
 in these occasional and hasty drawings, it is necessary to 
 make a guide for the piston-rod within the trunk, that the 
 bag may play up and down without rubbing on the sides, 
 which would quickly wear it out. 
 
 The experienced reader will see that this pump is very 
 like that of Gosset and De la Deuille, described by Belidor, 
 vol. ii. p. 120, and most writers on hydraulics. It would be 
 still more like it, if the bag were on the under side of the 
 partition E, and a valve placed further down the trunk. But 
 we think that our form is greatly preferable in point of 
 strength. When in the other situation, the column of water 
 lifted by the piston tends to hurst the bag, and this with a 
 great force, as the intelligent reader well knows. But in the 
 form recommended here, the bag is compressed^ and the 
 strain on each part may be made much less than that which 
 tends to burst a bag of six inches diameter. The nearer the 
 rings are placed to each other the smaller will the strain be. 
 
 The same bag-piston may be employed for a forcing-pump, 
 by placing it below the partition, and inverting the valve ; 
 aiid it will then be equally strong, because the resistance in 
 this case too will act by compression. 
 
 3. An ingenious variation in the construction of the sucking- 
 pump, is that with two piston-rods, in the same barrel, in- 
 vented by Mr. Walter Taylor, of Southampton. A vertical 
 section of this pump is given in fig. 224. 
 
 The piston-rods have racks at their upper parts working on the opposite 
 sides of a pinion, and kept to their proper positions by friction-rollers. 
 The valves used in this pump are of three kinds, as shown at a, b, and r. 
 The former is a spheric segment which slides up and down on the piston- 
 rod, and is brought down by its own weight; the second, b, is called the 
 pendulum-valve ; and the third, c, is a globe which is raised by the rising 
 water, and falls again by its own weight. Each of these valves will dis- 
 engage itself from chips, sand, gravel, &c. brought up by the water. In 
 this kind of pump the pistons may either be put in motion by a handle in 
 the usual way, or a rope may pass round the wheel rf e in a proper groove, 
 the two ends of which, after crossing at the lower part of the wheel, may 
 be pulled by one man or more on each side. A pump of this kind, with 
 seven inch bore, heaves a ton 24 feet high in a minute, with ten men, five 
 only working at a time on each side. 
 
 Another improvement of the common pump has been made 
 by Mr. Todd, of Hull. This invention in some particulars 
 bears a resemblance to the ordinary one, but he has con- 
 trived to double its powers by the following means : 
 

 AND MACHINIST* 25/ 
 
 Having prepared the piston-cylinder, which may be 12 feet 
 high, he cuts from the bottom of it about three feet ; at 
 the end of the great cylinder he places an atmospheric-valve, 
 and to the top of the small cylinder a serving-valve. In the 
 bottom of the small cylinder, which contains the serving- 
 valve, is inserted an oblong elliptical curved tube, of equal 
 caliber w ith the principal cylinder, and the other end is again 
 inserted in the top of the great cylinder. This tube is divided 
 in the same manner as the first cylinder, with atmospheric 
 and serving valves, exactly parallel with the valves of the 
 first cylinder. The pump, thus having double valves, pro- 
 duces double effects, which effects maybe still further increased 
 by extending the dimensions. 
 
 The cylinder is screwed for service on a male tube screw^y 
 which projects from the side of a reservoir or water cistern, 
 and is worked by hand. 
 
 The piston-plunger is worked by a toothed segment- wheel, 
 similar to the principle of the one used in working the chain- 
 pumps of ships belonging to the royal navy ; and the wheel 
 receives its motion from a hand-winch, which is considerably 
 accelerated by a fly-w^heel of variable dimensions, at the 
 opposite end. 
 
 This pump, in addition to its increased powers, possesses 
 another very great and prominent advantage. By screwing 
 to it the long leather tube and fire-pipe of the common engine, 
 it is in a few minutes converted into an effective fire-engine^ 
 Hence, whoever possesses one may be said to have a con- 
 venient domestic apparatus against fire. Three men can 
 work it, one to turn the winch, another to direct the fire- 
 pipe, and a third to supply the water. 
 
 4. The Forcing-pum]} is represented in fig. 225^ 
 
 It raises water through the box H, not in the same manner as the 
 sucking or lifting pump does, when the plunger or piston g is lifted up 
 by the rod Drf; but this plunger or forcer has no hole through it, to 
 let the water in the barrel B C get above it, when it is depressed to B ;• 
 and the valve b (which rose by the ascent of the water through the box H 
 when the plunger g was drawn up) falls down and stops the hole in H 
 the moment that the plunger is raised to its greatest height. Therefore 
 as the water between the plunger g and the box H can neither get 
 through the plunger upon its descent, nor back again into the lower 
 part of the pump L e, but has a free passage by the cavity around H into 
 the pipe M M, which opens into the air-vessel K K at P, the water is 
 forced through the pipe M M by the descent of the plunger, and driven into 
 the air-vessel, and in running up through the pipe at P, it opens the valve 
 a, which shuts at the moment the plunger begins to be raised, because the 
 action of the water against the under side of the valve then ceases. 
 
 The water being thus forced into the air-vessel KK, by repeated strokes 
 
 s 
 
THE OPERATIVE MECHANIC 
 
 2B8 
 
 ot the plunger, gets above the lower end of die pipe G H I, and then 
 begins to condense the air in the vessel K K. For as tlie pipe G II is fixed' 
 air-tight into the vessel below F, and the air has no way to get out of the 
 vessel out through the mouth of the pipe at I, and cannot get out when the 
 mouth I is covered with water, and is more and more condensed as the 
 water rises upon the pipe, the air then begins to act forcibly by its spring 
 against the surface of the water at H ; and this action drives the water up 
 through the pipe I H G F,from whence it spouts in a jet S to a great height, 
 and is supplied by alternately raising and depressing the plunger which 
 constantly forces the water that it raises through the valve H, along the 
 pipe M M, into the air-vessel K K. 
 
 The higher the surface of the water II is raised in the air-vessel, the less 
 space will the air be condensed into, which before filled that vessel; and 
 therefore the force of its spring will be so much the stronger upon the 
 water, and will drive it with the greater force through the pipe at F ; and as 
 the spring of the air continues whilst the plunger 5- is rising, the stream or 
 jet S will be uniform as long as the action of the plunger continues; and 
 when the valve b opens to let the water follow the plunger upward, the 
 valve a shuts, to hinder the water, which is forced into the air-vessel, from 
 running back by the pipe M M into the barrel of the pump. 
 
 If there was no air-vessel to this engine, the pipe GHI would be joined 
 to the pipe M M N at P: and then the jet S would stop every time the 
 plunger is raised, and run only when the plunger is depressed. 
 
 Mr. Newsham's Water-engine^ for extinguishing fire, (see 
 Fire-engine,) consists of two forcing-pumps, which alternatelv 
 drive water into a close vessel of air; and by forcing the 
 water into that vessel, the air in it is thereby condensed, and 
 compresses the water so strongly, that it rushes out with 
 great impetuosity and force through a pipe that comes down 
 into it; and makes a continued uniform stream, by the con* 
 densation of the air upon its surface in the vessel. 
 
 By means of forcing-pumps, water may be raised to anv 
 height above the level of a river or spring; and machines may 
 be contrived to work these pumps, either by a running stream, 
 a fall of water, by horses, or by steam. 
 
 The rod of the bucket in a sucking-pump is sometimes 
 made to work through a collar of oiled leathers and brass 
 plates, connected with the barrel of the pump by screws, and 
 kept moist by water contained in a vessel at the top : it 
 prevents the water issuing from the top of the pump, and 
 therefore by a pipe it will raise to any height. This is called 
 in the North a jaekhead. 
 
 5. llie Lifting-pump differs from the sucking-pump only 
 in the disposition of its valves, and the form of its piston 
 frame. This pump is represented in fig. 226. 
 
 A U is a barrel fixed i-n a frame I K L M, which is immovable, with 
 its lower parts communicating with the water. G E Q H O is a frame 
 with two strong iron rods, movable through holes in the upper and 
 lower parts of the pumps I K and I. M ; in the bottom of this frame 
 
jPiTiYrps 
 
 From 225 to 2S1 
 
 toliliu 
 
AND MACHINIST. 
 
 259 
 
 G Q H, is fixed an inverted piston B D, with its bucket and valve upon 
 the top at D. Upon the top of the barrel there goes off a part F R, either 
 fixed to the barrel, or movable by a ball and socket ; but in either case 
 water and air tight. In this part, at C, is a fixed valve opening upw’ards. 
 It is evident that when the piston frame is thrust down into the water, the 
 piston D descends, and the water below will rush up through the valve D, 
 and get above the piston ; and that, when the frame is lifted up, the piston 
 will force the water through the valve C up into the cistern P, there to run 
 off by the spout. The piston of this pump plays below the surface of the 
 water. Mr. Martin. has described a mercurial pump, which works by 
 quicksilver, invented by Mr. Hoskins, and perfected by Mr. Desaguliers ; 
 and another pump of the lifting sort, invented by Messrs. Gosset and De 
 la Deuille, and set up in the king of France’s garden at Paris, the piston 
 of which works without friction. — Phil. Brit. vol. ii. p. 57, &c. ed. 3. 
 
 6. Ctesibius's 2 mmp, the first of all the kinds, acts both by 
 suction and pulsion. 
 
 Its structure and action are as follows : A brass cylinder A B C D, fig. 
 227, furnished with a valve in L, is placed in the water. In this is 
 fitted an embolus M K, made of green wood, which will not swell in the 
 water, and adjusted to the aperture of the cylinder with a covering of 
 leather, but without any valve. In H is fitted on another tube N H, with 
 a valve that opens upwards in I. 
 
 Now the embolus MK being raised, the water opens the valve in L, and 
 rises into the cavity of the cylinder; and when the same embolus is again 
 depressed, the valve I is opened, and the water driven up through the 
 tube H N. 
 
 This is the pump used among the ancients, and that from 
 which both the others are deduced. Sir S. Morland has 
 endeavoured to increase its force by lessening the friction, 
 w’hich he has done to good effect, insomuch as to make it 
 work without almost any friction at all. 
 
 7. In 1813, the Society for the Encouragement of Arts 
 conferred a silver medal on Mr. John Stevens, for an im- 
 provement in the construction of the forcing-pump, by which 
 he is enabled, at a comparatively trifling expense, to raise 
 w’ater from a well 66 feet below the surface of the ground. 
 The whole expense of the pump and apparatus was 25/. 
 
 The lower part of the pump-tree is four inches in the bore. 
 The lower part of the rod which passes through the stuffing- 
 box is made of brass ; the elbow and upper pump-trees are 
 of a two-inch bore, and may be easily made of any kind of 
 wood. It may also be made to act as an engine to extin- 
 guish fires, by the addition of an air-tight vessel and pipe to 
 the upper part. 
 
 In the drawing is introduced a cap and screw, in preference 
 to screwing it to the nozle of the pump, as it is stronger 
 and more to be depended upon; and wffien the water is to be 
 raised a great height, a screw is also recommended to be 
 
 s2 
 
26 a 
 
 THE OPERATIVE MECHANIC 
 
 made to fit tJie nozle, that every thing may be always ready 
 for immediate use. The work of this pump is not liable to be 
 injured by frost ; and when the well is of considerable depth 
 a brass or metal barrel for the piston to work in should be 
 adopted. 
 
 Fig. 228 is a section of a well, in which a pump of this kind is fixed j 
 A A represents the surface of the ground, and B B the brickwork of the 
 well, in which the water stands at the level C, and is, by the pump, to be 
 raised ta the surface A A. 
 
 D is the lever or handle of the pump, which has the rod a jointed to it, 
 and descending to the pump ; the rod is made of wood, in several lengths^ 
 which are united by joints of iron, in the manner shown at fig. 229 ; the 
 wooden rods, a a, being capped with iron forks 6, which include the ends of 
 them and are nvetted fast; the ends of the forks are joined together to 
 connect the several lengths. 
 
 E is the working barrel, or chamber, of the pump, in which the bucket 
 works ; this part is formed of a tree, bored through and having a projecting 
 branch e, wliich is fikewise bored obliquely to the barrel, and forms the 
 forcing pipe ; in the bottom of the barrel the suction-valve is situated, being 
 at the top of the suction part of the pump, which is bored with a smaller 
 auger than the working chamber, which is also lined with a brass tube, 
 where the bucket works. The top of the barrel is covered by a metal lid, 
 ,g, (see figs. 230 and 231,) which has a stufting-box in the centre to receive 
 the metal cylindrical part of the pump-rod h ; to the lower extremity of this 
 the bucket a is fixed. The metal lid consists of a ring, which is screwed to 
 tl'.e wooden barrel by five screw-bolts, passing through as many ears, pro 
 jecting from the circumference of the ring; they have eyes below to hook 
 upon pins, which are fixed in the wood, but project sufficiently for these 
 bolts to hold, and are formed into screws above, so as to hold the ring 
 firmly down, by means of nuts screwed upon them. Tlie movable lid of 
 the pump, w'hicli has the stuffing-box formed in the centre of it, is screwed 
 to the ring by five screws, and these can be taken out to remeve the lid, 
 and draw up the bucket, when it requires to be leathered. 
 
 F is the forcing pipe, formed of as many pieces of wooden pipes as are 
 re(|uired to make up the length; they are united together by making the 
 upper ends conical, to enter a similar cavity made in the lower end of the 
 next pipe ; the lowest piece fits upon the extremity of the projecting branch 
 e, and a valve is proposed to be put in the pipe at this joint, to prevent the 
 return of the water, and bear part of the weight of the column from the 
 lowest valve at f; the upper end of the pipe has a spout i, at which the 
 water is delivered. 
 
 M is a second spout, fixed into the pipe lower than the former ; it has a 
 screw by which it can be united to a hole, or leather pipe, to convey the 
 water to a distance, or by means of a jet, or branch-pipe, to throw it in the 
 manner of a tire-engine; in this case the upper spout i must be stopped up, 
 by a screw-plug or cap ; and there is a copper air-tight vessel II, situated 
 at the top of the pipe F, to equalize the pulsative motion of the water as 
 thrown by the pump. 
 
 K is a bracket fixed to the pipe F, and projecting over the centre of the 
 ymmp, where it has a hole to receive the pump rod h, and guide it steadily 
 m its motion up and down, that it may not wear the stuffing-box away on. 
 one side. As the wooden tubes of which the forcing-pump F is composed 
 may be made from waste or crooked timber, it makes a great difference 
 
AND MACHJNIST. 
 
 2Gl 
 
 between the low price of such, and that of the stiaignt trees necessary for 
 common pumps. A wooden plug may be chained to the pump, betwixt 
 the spouts or nozles M and so as be ready to stop that which is not wanted 
 in use. 
 
 Mr. Stephens is of opinion, that it is better to place the 
 valve / above the level of the water in the well. 
 
 8. Mr. William Tyror, of Liverpool, took out a patent in 
 March, 1819, for certain improvements in the construction 
 of pumps, and in the machinery for working the same. 
 
 This improvement consists in having four bmss chambers, marked P P P, 
 fig. 232, joined together by means of breech-pieces with screw’s, and 
 soldered across the joints ; these breech-pieces, marked Q, Q, being cast 
 of brass, or any other suitable metal. When these are complete, P P, 
 fig. 233, is placed upon the breech-piece Qq, fig. 234, and both of them are 
 fixed to or under a box or frame suitable for the purpose. 
 
 This box or frame, fig. 238, is furnished with eight brass grooves, 
 •O OO, fastened to the sides with screws; and a crank, or four cranks in 
 one, that is, one crank out of each side of the same piece of square iron or 
 any other suitable metal, one up, one down, one in front, and one in back. 
 To one end of the crank, or cranks, is fixed two tooth and pinion wheels, 
 a sufficient distance apart to allow two wheels of the same diameter and 
 thickness to stand between them, so that the cranks may go round without 
 moving the other wheels, marked C and E. The wheels D and F are 
 made fast on the cranks A, A, by means of a screw or pin, and the wheels 
 C and E, being fixed close together, slide to and fro upon the square end 
 of the axle U, by means of the guide or sliding geer V, which is fixed in 
 a groove turned out of the nave of the wheel C, by means of a clip and two 
 screws which fasten it underneath, and rests in the notches fixed at the 
 other end of the box or frame, for the end of the guide or geer to rest. 
 
 The notches are three in number on each side of the box or frame W. 
 The one farthest from the wheel has the guide V, drawn back, with the 
 wheel E upon the small wheel F. By moving the guide into the middle 
 notch, the w'heels C and E are kept between the wheels D and F ; and the 
 notch nearest the w’heels guides the wheel C on the large .wheel D, so that 
 the power is much greater when forcing or drawing water from a great 
 depth. 
 
 When the wheels C and E are placed in the space between the lower 
 wheels, the handle is moved from the upper axle U, and placed upon the 
 end of the crank A A, and the pump is w’orked without the assistance of 
 the W’heels as occasion may require. The machinery is furnished with four 
 key-bow rods, marked B B B, for the purpose of fixing to them the spear 
 boxes or plunging rods, by means of a joint and pin and bolt, the key-bow 
 being filed square across in the inside, so as to give the roller-step a fair 
 bearing. 
 
 Fig. 235 represents the rolling-step, which is formed of two pieces of 
 brass, the one half round, of a thickness according to the strength or size of 
 the machinery ; and the other round, like a wheel or sheave in form, and of 
 the same thickness as the other half. This round sheave or wheel is cut half 
 through the middle edgeways, and the piece is then cut off, and a dovetail 
 is cut down the width in proportion to the crank. Tlie other half is then 
 fitted into the place from whence the larger piece has been cut, and both of 
 them are held together by means of two screws ; and the sheave or wheel is 
 then in the form of its appearance before it was cut. A hole is now drilled 
 
262 
 
 Till*: OPERATIVE MECHANIC 
 
 through tlie centre, and it is fixed upon the before mentioned crank or 
 cranks. Y, in fig. 236, represents the larger half of this step; and X, fig. 
 237, represents the smaller half, with the dove-tailed standing upon it, 
 which fills up the vacancy or room that is made in the large half for fixing 
 it upon the crank. 
 
 The ends of each key-bow is set in the grooves, 0 0 0 , fig. 238, and the key- 
 bow rods, B B B B, work through holes in the bottom of the box, for which 
 purpose an iron-plate or base is formed with four holes, SS S, fig. 239, 
 and is fixed at the bottom of the box or frame with screw's. The rods, by 
 being fitted into the holes in this plate, keep the stroke of the. pump per- 
 pendicular, while the step rolls backwards and forwards in the key-bow, as 
 they are forced up and down by the cranks moving or turning alternately 
 round. 
 
 When this machinery is applied over a forcing-pump, or placed over a 
 fire-engine, it causes a greater quantity of v/ater to be discharged from the 
 cistern or engine, and as it is very powerful, it is highly necessary that it 
 should have a cock of a superior size, to let more water pass through in the 
 same time than ordinary ; for this purpose Mr. Tyror makes the barrel, 
 or that part of the cock where the key or stop goes in on one side, so that 
 there is but one stop to the plug or key, the stop, resting in that part that 
 overhangs the side, admits of room for a full sized water-way to be com- 
 pletely through it, without causing the water to have any bubble or curl 
 as it passes through the plug. 
 
 Reference to the figures : 
 
 Tig. 240 represents a side view of the cock. 
 
 ' Fig. 241, a top view of the same. 
 
 Fig. 242, the plug, with the water-way cut out. 
 
 Fig. 243 represents the crank, with the tooth and pinion wheels, and the 
 rolling steps. 
 
 Fig. 244, the upper axle, with the improved plan of the sliding geer. 
 
 Fig. 245, the spear box and rod in the form of the fastening at the top of 
 the key-bow rod, when applied for shipping. 
 
 Fig. 246, a front view of the pump standing upon a ship’s deck. 
 
 9. Mr. Richard Franklin has been rewarded by the Society 
 of Arts for effecting certain improvements in the lifting and 
 forcing pump, by which water can be conveyed into a cistern 
 at the top of the house, to supply all the dressing-rooms, 
 water-closets, &c. 
 
 A section of this pump is given in fig. 247. 
 
 AA are two pistons ; on the upper face of each is a double valve, vvv v; 
 the upper piston-rod passes through the stuffing-box B, and the lower 
 through the stuffing-box C. S is the suction-pipe, and D the discharging- 
 pipe. 
 
 Fig. 248 is an external view of the pump ; e ee the lever or handle; F 
 the fulcrum, on which the handle moves ; G G is the pump-cylinder; w w 
 the wheels which revolve between the standards x oc xx, and which conduct 
 the piston-rods parallel to the cylinder ; ejt? the conducting-rod, which con- 
 veys the n:otion of the handle to the lower piston; eo the conducting-rod, 
 which gives motion to the upper piston. It is evident, when the handle or 
 lever is lifted, that the upper piston is pressed down, and the lower piston is 
 at the same time elevated, with its valves shut, w'hich forces the water 
 through the upper piston and the discharging-pipe at the same operation. 
 
If p OYiF nr o'.iR 
 
 j From 232 to 2 ^6 PI. 20. 
 
 j 2W P42 238 
 
 ^erle SeStfichl^ se 3S 2 Stra^t^ 
 
AND MACHINIST. 
 
 263 
 
 And when the handle is pn^ssed down, the upper piston rises w ith its valves 
 closed, and the water in its ascension is forced throvigh Ihe discharging- 
 pipe ; at the same time the lower piston descends, by which action its valves 
 are opened, and introduces a supply of water equal to the contents of the 
 cylinder, minus the capacity of both pistons. The peculiar advantages of 
 this pump with double pistons are, that with a six-inch stroke it discharges 
 a quantity of water equal to twelve inches of the cylinder : and so, in this 
 proportion, by always doubling the quantity of the stroke, whatever it may 
 be ; and thus furnishing a product just equal to two common pumps of the 
 same stroke and capacity of cylinder, and certainly with less than a pro- 
 portionable friction and expense. 
 
 10. The pumps^?X are usually employed for araining mmes 
 have many iiiconveiiiencies, the principal of which we shall 
 here proceed to describe. 
 
 1st. As it is necessary for the pumps, whilst sinking, to keep the water 
 veiy low in the pit, the engine frequently goes too fast, in consequence of 
 the pump drawing up air, and carries up by the violence of the current 
 small pieces of stone, coal, or other substances, and lodges them above the 
 bucket upon the valves, which must considerably retard the working of the 
 pump, and wear the leather. 
 
 2dly. When the engine is set to work, (after having been stopped whilst 
 working upon air, and consequently a quantity of air remaining in the pump- 
 barrel, with the small stones, &c. deposited on the valves of the bucket,) it 
 often happens that the compressure of the air by the descent of the bucket, 
 is not sufficient to overcome the weight of the bucket-valves so loaded with 
 rubbish, and the column of water in the stand-pipes ; the pump is thereby 
 prevented from catching its water. The usual remedy for this is to draw 
 the bucket out of the working-barrel, until a quantity of water has escaped 
 by its sides to displace the air ; this evil often arises from the unnecessary 
 magnitude of the space between the bucket and the clack. 
 
 3dly. The pumps being suspended in the pit by capstan ropes, for the pur- 
 pose of readily lowering as the pit is sunk, the stretching of the ropes 
 (especially when sinking in soft strata) occasions much trouble, by suffering 
 the pumps to rest on the bottom and choke ; but the most serious evil is, 
 that the miners, in shifting the pump from one place to another, that they 
 may dig in all parts of the pit, throw' them very far out of the perpendicular, 
 thereby causing immense frictipn and wearing in all parts, besides endan- 
 gering the whole apparatus, by breaking the bolts and stays, and straining 
 the joints of the pipes. 
 
 These iiiconvemencies have been obviated by Mr. William 
 Brunton, of Butterley Iron-works, in Derbyshire, who, to 
 avoid the pump drawing air, has introduced a side pipe, con- 
 necting the parts of the working-barrel which are above and 
 below the bucket, which pipe has a stop-valve, that the 
 miners can regulate wdth the greatest ease, so as to keep 
 the engine to its full stroke without drawing air, by letting 
 <iown the water from the upper part of the barrel into the 
 lower, so that it is working again in its own water. Instead 
 of having the whole weight of the lower lift of pumps stand- 
 ing on the bottom, it is fixed in the pit by cross beams, and 
 
THK OPERATIVE MECHANIC 
 
 264 
 
 the miner has only to lift and move an additional pipe or wind- 
 bore which slides upon the lower end of the pump like a 
 telescope, to lengthen down, and this additional wind-bore is 
 besides crooked, and turned aside like a short crank, which, 
 by the facility with which it turns ibund in the leather collar 
 about the nose of it, can easily be removed into every fresh 
 hole which is made in the bottom by the miners. The pumps 
 are supported in the pit by beams placed across at proper 
 distances, so as to suit the lengths of the pipes, or lengths of 
 the pump, which are nine feet. Short pieces are laid across 
 these, with half-circular holes in them, which being put round 
 the pump, just beneath the flanches, firmly support its weight, 
 but may quickly be removed, when it is required to lower the 
 pumps in the pit ; and as they are not fastened by any bolt 
 they do not prevent the pumps being drawn upwards, if it 
 becomes necessary to take out the pumps when the pit is full 
 of water. 
 
 The pumps by these means remain stationary, and the 
 suction-pipe lengthens as the pit is sunk, until it is drawn out 
 to its full extent ; the whole column is then lowered to the 
 next stanches, and another pipe is added to the top. The 
 pumps being thus kept stationary till nine feet are sunk, the 
 pipe at the top will of course deliver the water at the same 
 level at all times, and instead of being obliged to lengthen the 
 column at every yard sunk, it will only be necessary every 
 nine feet. 
 
 Fig. 249 explains the construction of Mr. Brunton’s pump, being a sec- 
 tion through the centre of the working-barrel and suction piece. A is the 
 door which unscrews to get at the clack of the pump ; B is the working- 
 barrel with the bucket D working in it ; E is the clack, also shown in figs. 
 250 and 251 ; F is the suction-pipe, and G G a movable lengthening piece : 
 this slides over and includes the other when the pump is first fixed ; but as 
 the pit is sunk, it slides down over the pipe, F, to reach the bottom. The 
 outside of the inner pipe F is turned truly cylindrical and smooth, and the 
 inside of the outer pipe G, at the upper end for about six inches down, is 
 made to fit it. The junction is made perfect by leathers being placed in 
 the bottom of the cup a a, which holds water and wet clay over them, to 
 keep them wet and pliable, and consequently air-tight. The lower ex- 
 tremity of the suction-pipe G terminates in a nose R, pierced with a number 
 of small holes that it may not take up dirt. This nose is not placed in a 
 line with the pipe, but curved to one side of it like a crank, so as to describe 
 a circle when turned round. 
 
 By this means the miners, by turning it round upon the pipe F, can 
 always place the nose R in the deepest part of the pit ; and when they dig 
 or blast a deeper part, they turn the nose about into it, the sliding lube 
 lengthening down to reach the bottom of the hole, as shown in the figure. 
 By this means there is never a necessity to set a shot for blasting so near 
 the pump foot as to put it in any danger of being injured by the explosion* 
 as IS the case of the common pump, in which this danger can only be 
 
Z47 
 
 I^FMIPS 
 Frorriy 24 7 to 251 
 
AXD MACHINIST. 265 
 
 avoided by moving the pump foot to one side of the pit, which necessarily 
 throws the whole column of pumps out of the perpendicular. 
 
 The construction of the clack is explained by figures 250 and 251, the 
 former being a section, and the latter a plan. L L is a cast-iron ring, fitting 
 into a conical seat in the bottom of the chamber of the pump, as shown in 
 fig. 249 ; it has two stems, I /, rising from it to support a second iron ring 
 MM ; just beneath this a bar m extends across from one stem to another, 
 and has two screws tapped through it ; these press down a second cross 
 bar n, which holds the leather of the valves down upon the cross bar of the 
 ring L, and this makes it fast, forming the hinge on which the double valves 
 open, without the necessity of making any holes through, as is common : but 
 the chief advantage is, that by this means the clack can be repaired, and a 
 new leather put in, with far less loss of time than at present, an object of the 
 greatest importance ; for in many situations the water gathers so fast in the 
 pit, that if the clack fails, and cannot be quickly repaired, the water rises 
 above the clack door, so as to prevent any access to it, and there is no 
 remedy in the common pump but drawing up the whole pile of pumps, 
 which is a most tedious and expensive operation. 
 
 In Mr. Brunton’s pump, the clack can at any time be drawm out of it, by 
 first drawing out the bucket, and letting down an iron prong Z, which has 
 hooks on the outside of its two points ; this, when dropped down, will fall 
 into the ring M, and its prongs, springing out, will catch the under side, and 
 hold it fast enough to draw it up. Another part of Mr. Brunton’s improve- 
 ment consists in the addition of a pipe H, (fig. 249,) which is cast at the 
 same time with the barrel, and communicates with it at top and bottom, 
 just above the clack ; at the upper end the pipe is covered by a flat sliding 
 plate, which can be moved by a small rod 6, passing through a collar of 
 leather ; the rod has a communication by a lever, so that the valve can be 
 opened or shut by the men in the bottom of the pit. 
 
 The object of this side pipe is to let down such a propor- 
 tion of the water which the pump draws, as will prevent it 
 drawing air; though, of course, the motion of the engine will 
 be so adapted as not to require a great proportion of the 
 water to be thus returned through the side pipe ; yet it will 
 not be possible to work the engine so correctly as not to draw 
 some without this contrivance ; and if it does, it draws up 
 much dirt and pieces of stone into the pump, besides causing 
 the engine to work very irregularly, in consequence of partially 
 losing its load every time the air enters the pump. Another 
 service of the side pipe is, to let water down into the chamber 
 of the clack to fill it, when the engine is first set to work, after 
 the pumps have been standing still, and the lower part of the 
 barrel and chamber are empty. 
 
 1 1 . Figures 252 and 253 are a section and elevation of 
 a three-barrel force-pump, of a very good construction, which 
 was used by Mr. Smeaton in the numerous water-engines 
 which he erected at London-bridge, Stratford, and other 
 places, for the supply of towns with water. It has the ad- 
 vantage^f the valves being very accessible, and the water-way 
 may be kept to the full size of the barrel without contractions. 
 
266 
 
 tk;e operative mechanic 
 
 which, as they occasion great resistance to the motion of the 
 water, are a waste of power. It acts on the same principle 
 as the ordinary forcing-pump, only that three barrels are con- 
 nected together for the advantage of raising a constant stream 
 of water. 
 
 A A are the barrels, which are bored out truly cylindrical. If the pump 
 is small, the barrels are usually made of brass ; but for larger work, cast-iron 
 is used. From one side, near the bottom of each, proceeds a curved pipe B, 
 turning up, and ending with a flaunch, to screw to the under side of the forcing- 
 chamber L. There is also, near the bottom at the opposite side of the barrel, 
 a projecting neck or short pipe D, covered at the end by a door screwed on, 
 that it may be removed to give access to the valve «i, in the bottom of 
 the barrel. The barrels have projecting rings or flaunches, by w'hich they 
 are screwed down upon the suction-chamber H, which is common to all 
 three barrels ; it has a pipe from each of its rods terminating in a flaunch /i, 
 to screw on the pipes which bring the water to the pump. The upper 
 flaunch, or top of the suction-chamber II, has three holes in it, one under 
 each barrel, and each is covered by a valve shutting downwards, as is shown 
 in the section, fig. 252. These valves are made of iron, to shut down upon 
 hinges like a door, and are covered with leather at the lower side. 
 
 Mr. Smeaton made his valves with the centre-pin of the 
 hinge removed backwards from the hole which the valve 
 covers, and it is also raised above the surface of the under side 
 of the valve, by which means the valve opens in some degree 
 on that side where the hinge is, as well as on the other, and 
 any obstruction getting into the valve will be less liable 
 to be detained, and will not have such a great leverage to 
 break the hinge of the valve when the force of the water shuts 
 it down, as it would if the hinge was on a level, and close to 
 the edge of the hole, because the obstacle will not be so near 
 the centre. 
 
 The binge is fastened to the pump by the screw v), passing through the 
 metal, and screwing into the hinge ; this being withdrawn, and the door D 
 opened, the valve is quite loose, and may be taken out to renew the leather. 
 To give facility to this, the doors D are made oval, as shown in fig. 253. 
 Another similar valve n is fitted at the top of each of the pipes B, to cover 
 their apertures ; they are all covered by a common forcing-chamber L, 
 which is exactly similar to the suction-chamber, except that it has nozles R, 
 in the top over each \alve, and covered with doors to give access to them. 
 The conducting-pipes are carried away from either end of the forcing- 
 chamber, flaunches being provided to unite them. Each barrel is fitted with 
 a piston or fcorcer M, which consists of three metallic plates, secured to the 
 rod : the middle plate is turned true, and fitted as accurately as possible to 
 the barrel ; the upper and lower plates are somewhat smaller. Two round 
 pieces of leather, larger than the barrel, are placed above and below the 
 middle plate, being held fast between it and the upper and lower plates. 
 When forced into the barrels, these leathers turn up and down round the 
 tipper and lower plates, forming two cups of leather, which accurately fit 
 the barrel, and will not permit any fluid to pass by them. 
 
 The parts of the pump are fastened together by screws and nuts, as will 
 
AND MACHINIST. 
 
 267 
 
 be understood by inspection of the figures. The whole pump is supported 
 on two ground-sills, and by means of two uon branches of the suction- 
 chamber H, the whole pump is bolted down upon the ground-sills. 
 
 The action of this pump is simply this : when the piston or 
 forcer of one barrel is raised, it causes a vacuum in it, and 
 the pressure of the atmosphere forces the water up the suction- 
 pipe H, (if not more than 30 or 33 feet,) opens the valve m, 
 in the bottom of the barrel, and fills it with water ; on the 
 descent of the forcer, the lower valve shuts, and the forcing 
 valve n opens, by the water the barrel contained being driven 
 through it into the forcing-chamber L, and thence to any 
 place whither the forcing-pipe is carried. On the reascent 
 of the forcer, the lower valve m opens, and the shutting of 
 the forcing-valve n prevents the water returning into the 
 barrel. Tlie three forcers wwk up and down alternately, so 
 that while one barrel is sending water up the force-pipe, the 
 others are lifting it up the suction-pipe, and the third con- 
 tinues the action in the interval, when the change of motion 
 takes place between the two. In this manner the pump will 
 raise a very constant stream of water, if the forcers are 
 worked in a proper manner ; which is best done by means of 
 cranks, placed at such an angle to each other, upon the same 
 axis, that they will act in due succession. 
 
 12. English ships of war carry four chain-pumps and three 
 
 hand-pumps, all being fixed in the same well, which also 
 includes the mainmast. ^ 
 
 The chain-pump (fig. 254) is no other than a long chain A, with a suffi- 
 cient number of pistons, a, called buckets or saucers, fixed \ipon it at proper 
 distances; it passes downwards through a wooden tube B, and returns 
 upwards in the same manner, on the other side D, the ends being united 
 together. The chain is extended over two wheels, E and F, called sprocket- 
 wheels ; one is placed over the tubes B and D of the pump, and the other 
 at the bottom in the space between the two tubes through which the chain 
 ascends and descends. By turning the upper wheel E, the chain of buckets 
 is put in motion, and the lower part of the wooden tube, in which the chain 
 ascends, is lined with a brass barrel, in which the saucers are fitted. As 
 they are continually ascending in this tube, they raise a constant stream of 
 water, which runs off from the top of the ascending trunk, and is carried by 
 a trunk through the ship's side into the sea. The pump is worked by a 
 crank or winch G, fixed on the axis of the upper wheel, whereon several men 
 may be employed at once ; and thus it discharges in a limited time a mucli 
 greater quantity of water than the common pump, and that with less incon- 
 venience to the labourers. 
 
 13. The chain-pump now in use in the navy is of a very 
 improved construction, compared with original chain-pumps. 
 It was introduced by Mr. Cole, under the direction of Capt. 
 Bentinck. The chain of this machine is simple, and not 
 much exposed to damage. U is exactly similar to that of the 
 
268 
 
 THE OPERATIV'E MECHANIC 
 
 fire-engine, and appears to have been first applied to the 
 pump by Mr. Mylne, to exhaust the water from the caissons 
 at Blackfriars-bridge. It has thence been transferred to the 
 marine by Capt, Bentinck, after having received some material 
 additions to answer that service. 
 
 The links of the chain (fig. 255) are each formed of two long plates of 
 iron, e e, with a hole at each end, and fixed together by two bolts, serving 
 as pins for the joints. The buckets or saucers fixed upon it are two circular 
 plates of brass, g, with a piece of leather between them. The sprocket- 
 wheels for the chain are formed in the same manner as the trundles used in 
 mills, by two iron wheels fixed at eight inches distance upon the axles, and 
 united by several round iron bolts, forming a rest for the chain ; and its 
 links have hooks, 6, which are taken by these bolts, and thus the chain is 
 secured upon the wheel, to prevent it from jerking back when charged with 
 a column of water. 
 
 This pump was a great improvement upon the old chain- 
 pumps used in ships before, in which the chain was of too 
 complicated a fabric, and the sprocket-wheels used to work 
 it were deficient, in wanting some contrivance to prevent the 
 chain from sliding or jerking back upon the surface of the 
 wheel, which frequently happened when the buckets were 
 charged with a considerable weight of water, or when the 
 pumps were violently worked. The links were too short, and 
 the awkward manner in which they were connected, exposed 
 them to a great friction in passing round the wheels : hence 
 they were sometimes apt to break or burst asunder in very 
 dangerous situations, when it was extremely difficult or im- 
 practicable to repair the chain. 
 
 Mr. Cole’s pump is so constructed, that the chain may 
 be easily taken up and repaired, when broken or choaked 
 with ballast ; and it discharges a much greater quantity of 
 water with an inferior number of men, as appears from a trial 
 of this machine with the old chain-pump, aboard the Seaford 
 frigate, where it was found that its effects, when compared 
 with the latter, were as follows : — The new pump with four 
 men raised one ton of water in 43J seconds, while the old 
 pump required seven men to raise the same quantity of water 
 in 76 seconds. 
 
 In this experiment the chain of the new pump was pur- 
 posely broken, and dropped into the well, and afterwards 
 taken up and repaired, anid set to work again in two minutes 
 and a half ; then the lower wheel of the pump was taken out, 
 to show how readily it might be cleared and refitted for 
 action, after being choaked with sand or gravel, which could 
 be performed in four or five minutes. These are advantages 
 which, with a seaman, have a superior consideration to that 
 
JPFMJPS 
 From 252 to 256 
 
 FI.32 
 
 254 
 
 253 
 
 SiStoeMt^ *c36Z Strond 
 

AND MACHINIST. 
 
 269 
 
 of increasing the quantity of water which the machine will 
 raise, unless it was in a considerable degree ; and indeed the 
 very best pumps will not raise a much greater proportion 
 with the same power. 
 
 The only alteration which has been made on Mr. Cole’s 
 pump, since its first introduction, near thirty years ago, is, 
 that they now omit the lower sprocket-w’heel altogether, the 
 ascending and descending pipes being so united by a curved 
 metal tube, that the chain passes better than if a wheel was 
 used. The cranks are made to take off, and apply, when 
 wanted, that they may not be in the way ; they are long 
 enough for thirty men to work at once ; of late it has been , 
 proposed to add fly-wheels to them. This would be attended 
 with but slight advantage, and several inconveniences from 
 occupying that room where the men should stand to work, it 
 being an object to employ as many as possible ; but if they 
 are crowded, they only incommode each other instead of 
 assisting. 
 
 14. The following simple and ingenious method of working 
 a ship’s pump, when the crew are either too few in number, 
 or too much exhausted to attend to that duty when the per- 
 formance is most necessary, namely, in a heavy gale, was 
 put in practice with great success by Capt. Leslie, of the 
 ship George and Susan, on a late voyage from Stockholm to 
 North America. He fixed a spar aloft, one end of which 
 was ten or twelve feet above the top of his pumps, and the 
 other projected over the stern ; to each end he affixed a block 
 or pulley. He then fastened a rope to the spears of the 
 pump, and after passing it through both pullies along the 
 spar, dropped it into the sea astern. To the rope he fastened 
 a cask of 1 10 gallons measurement, and containing 60 or 70 
 gallons of water. This cask answered as a balance-weight, 
 and every motion of the ship from the roll of the sea made 
 the machinery work. When the stern descended, or when 
 a sea or any agitation of water raised the cask, the pump- 
 spears descended ; and the contrary motion of the ship raised 
 the spears, when the water flowed out. The ship was cleared 
 out in four hours, and the crew were of course greatly 
 relieved. 
 
 15. Hand-pumps have been constructed in great variety 
 for the use of ships ; and as they are of great utility, w^e shall 
 describe two or three of the best. 
 
 The ingenious Benjamin Martin invented a ship’s pumn 
 with two barrels drawing from one suction-pump, so as to 
 raise a constant stream. 
 
THK OPERATIVE MECHANIC 
 
 270 
 
 This pump has so much merit, that we have given a section of it, fig. 250. 
 Here A is the suction-pipe, conducting the water from tlie ship’s hold up 
 to the pump, where it is enlarged to communicate with both barrels D D, 
 through the valves C C, in the bottom ; E E are the pistons of the barrels, 
 with double valves in them; they are not, like other pistons, fitted to slide 
 in the barrels, but are simply brass rings, in which the valves are fitted, and 
 being smaller than the barrels, have large circular pieces of leather fixed on 
 them, the outside edges of wliich are attached to the insides of the pump- 
 barrels ; hence, when the pistons are moved up and down, the leather folds 
 sufficiently to admit the motion, as is shown in the figure ; but being close 
 all round, these pistons can have no leakage or friction, and only a s.nali 
 resistance from the stiffness of the leather. 
 
 To fasten the edges of the leather piston to the barrels, they are made in 
 two lengths, an upper and a lower, and the leather is introduced in the 
 joint between them, being half fast, and the pump kept together by bars 1 1, 
 fixed over the barrels, and bolts to press the upper length of the barrels 
 down upon the lower. Both the barrels are included within a box or cis- 
 tern B B, fixed upon the ship’s deck, with trunks L L, which carry off the 
 water as it runs over the tops of the barrels into the cistern. The pump is 
 worked by piston-rods II H, being united by chains to a wheel K, the axle 
 of which is supported by standards from the sides of the cistern B B, and 
 is put in motion by the double lever M, at the end of whicli cross handles 
 are fixed for several men to work at once. Mr. Martin’s pump acts ex- 
 tremely well; the constant stream raised by the alternate action of two 
 barrels upon one pipe, produces an advantage that was shown by experi- 
 ment, for the water not only rises while the piston rises, but continues to 
 do so even after the piston begins to descend ; and therefore the pump was 
 found to deliver more water than was expected from the calculation of the 
 contents of the barrel, and the number of strokes made. 
 
 To account for this, it must be considered, that as this 
 pump has both its large pistons working (alternately ascending 
 and descending) at the same time, there must be produced a 
 constant rising column of water in the pipe, whose velocity 
 through a bore of five inches, to supply the barrels of twelve 
 inches diameter each, must be so great, that it cannot be 
 checked or stopped at once, or upon the first descent of the 
 piston ; and therefore a surplus of water is produced. Not- 
 withstanding these advantages of Mr. Martin’s pump, it has 
 objections, which are serious obstacles to its use on board 
 ships, though in other situations it is a good machine : these 
 are, the shortness of its stroke, which renders it very fatiguing 
 for men to work for a long time ; but another more serious 
 objection is, that the leather would, in general, remain dry, 
 and thus become liable to harden and grow stiff, so as to 
 break into holes when used at first, before they become soaked, 
 and to fill the cistern first with water would be very trouble- 
 some. 
 
 16. The latest improvements in hand-pumps are hy Capt. 
 Jekyl, R. N. This gentleman has invented an addition to the 
 pump of an air-vessel, and stuffing-box for the rod to pass 
 
AND MACHINIST. 
 
 271 
 
 through, by which it will raise the water to a greater height 
 than the head of the pump ; and a hose being attached I0 the 
 pump-spout, by very simple means, the water is conveyed to 
 any part of the ship, and thrown in a jet through a hose-pipe 
 with great force, to extinguish fire, if such a calamity should 
 befall a ship ; and thus the pump is rendered of twofold ser- 
 vice. The idea of converting the pump to a fire-engine is not 
 new, having been attempted in many ditferent ways by forcing- 
 pumps ; but these having pipes proceeding from the lower 
 parts of the barrels and valves, ■which are not very accessible, 
 are always liable to choke up by obstructions, and have not 
 succeeded in general use. The air-vessel has always been in 
 the way, if made of a sufficient size to answer the purpose of 
 equalizing the stream. Capt. Jekyl has obviated these objec- 
 tions, and without altering the material parts of the hand- 
 pump, has rendered it as complete a fire-engine as can be 
 wished. 
 
 Tliis is explained by figure 257 , which is a section of the pump through 
 its whole length. A B C is the iron brake or lever to work it ; it is branched 
 to the extreme end, and has a wooden pole C, fixed in it, for several men 
 to hold at once ; D is the iron stanchion or fulcrum of the brake ; it is fixed 
 to the pump-head by means of strong iron hoops at E E and E F, which at 
 the same time strengthen the w'ork of the pump. Tlie centre-piu is to be 
 at the height of two feet six inches above the ship’s deck. II are the slings 
 of the pump, united by a forelock or pin to the end of the brake, and sus- 
 pending the pump-spear I, by means of the joint-piece I K is the pump- 
 spear, made of copper in the upper pait I, and the lower length K of iron ; 
 the latter has the bucket M attached to it. Tire valve of the bucket is made 
 in a very simple and effective manner, the valve being merely a round plate 
 of brass, with a hole through the centre, to receive the rod upon whicli it 
 rises and falls, and covers the aperture in the bucket. Tire bucket is a ring 
 of brass, with a cross bar to fix the rod in ; it is made in two thicknesses, 
 one above the other, and a cup of leather is held in between them, projecting 
 all round the upper part of the bucket, and turning up, to make a tight 
 fitting in the barrel. The two rings of the bucket are lield together by the 
 piston-rod passing through both, and a cross wedge beneath. L is the brass 
 chamber in which the bucket works ; it is well fitted into the wood of the 
 pump-tree, so that the water cannot leak by it, and is bored smooth within- 
 side, 
 
 N is the lower box, fitted into the lower part of the pump-tree, beneath 
 the chamber ; it has a groove round it, into which oakum is placed, and 
 when it is put down, makes a tight joint; its valve is of the same construc- 
 tion as that of the bucket, with the addition of a ring or eye on the top of 
 the pin, on which the valve rises and falls. By this eye the box can be 
 draw n up when it needs repair, by first draw ing up the bucket of the pump, 
 and putting an iron dow n into this eye. O O P is the air-vessel ; this is a 
 cylinder of sheet-copper, soldered to a cover of brass; witliin the centre of 
 it is a tube likewise soldered to the cover, through which the copper pump- 
 spear passes, and is fitted round at top with a collar of leather and stuffing. 
 To prevent the escape of the water, it is packed with hemp, and two rings 
 of leather. R sliows the place of two iron bars, fitted through the head ot 
 
THK OPERATIVE MECHANIC 
 
 272 
 
 the pump, and confining tiie cover () O, of the air-vessel ; they are fastened 
 by the wedges d; it is by these only that tlie air-vessel is held down; a circle 
 of leather is first put round the air-vessel, just beneath its lid, and this being- 
 pressed upon the recess in the wood, makes the joint tight. T is the pump- 
 nozle, which delivers the water. When it is used as a fire-engine, a hose 
 is fixed on by its link-joints, and keys or wedges; the nozle is fixed to the 
 pump by four screw-bolts going through the thickness of the pump, and it 
 is fixed in such a direction as will most conveniently lead to a receiver, 
 fig. 258, which unites the hose from all three of the ship’s pumps.' 
 
 Fig. 259 is the link-joint of the hose, T representing the pump-spout, 
 made of cast-iron, and screwed to the pump-tree ; e e is the collar or socket, 
 made of brass, with the hose X bound upon it ; this has two trunnions, on 
 which a link f is fitted, one on each side ; these links pass through grooves 
 in the cast-iron piece T, and a key g, put down through the link behind it, 
 draws the joint tight, without any screwing or further trouble. The socket 
 c e is fitted into the nozle, and has a leather ring to make it tight. The 
 outside of the pump is to be hooped at every three feet, to prevent it from 
 bursting by the pressure of the water. The disposition of the three hand- 
 pumps in a ship’s well, renders their connection with a common receiver 
 very convenient to bring all the water into one stream, which will then be 
 very powerful, and more capable of extinguishing a fire than any movable 
 engine. 
 
 Two hand-pumps are always placed on the starboard side of the main- 
 mast, in the well ; and one of them being the cistern-pump used for washing 
 decks, its foot stands in a small cistern fixed upon the step of the mainmast, 
 and supplied with water by a pipe through the ship’s side, with a cock to 
 admit it at pleasure ; there is one pump on the larboard side of the mast. 
 Three separate hoses being united with each of the pumps by a link-joint, 
 like fig. 259, at one end, and with three necks li of a receiver, fig. 258, 
 by similar joints at the other, brings all the water into one, and a hose being 
 joined by a link-joint, I, to the opposite end of the receiver, conveys the whole • 
 water to any part of the ship. The receiver has three nozles, k k k, at one 
 end, made in a divergent direction, agreeable to the direction in -vsdiich the 
 hoses come from the three different pumps, and a valve is placed inside, 
 before each hose, to open inwards, in order that the receiver may be used 
 for one or two pumps, whilst the others are repairing or getting ready, or 
 that if any of the hoses burst, the water may not escape from the receiver at 
 the nozle. There are two handles fixed to the receiver, to lift and carry it, 
 as it is to be movable ; and when in use, is proposed to be laid upon the 
 grating of the main hatchway, as the most central situation, from whence 
 the hose may be carried in any direction. Z is a branch-pipe or jet, screwed 
 at the end of the great hose X ; and it also unscrews at the extreme end, to 
 fit on jets of different bores, in the same manner as all other fire-engines. 
 In working, the pressure of the water condenses the air contained within 
 the receiver, OOP, into a small space, and its reaction to resume its 
 former bulk equalizes the efflux of the water from the nozle of the pump. 
 
 In some experiments which we have witnessed upon this 
 pump, it performed as well as could be desired, a single pump 
 forming a very elective engine ; but when the three were 
 combined, it was superior in force to any we have ever seen, 
 and would throw a stream of an inch in diameter over the 
 maintopmast-head of a 74-gun ship. 
 
 Besides the length of the handle G admitting sever.al men to work at 
 once, an accession of force is gained by a rope % made fast to the brake A B,. 
 
AND MACHINIST. 
 
 273 
 
 and conducted through a single block hooked to the deck at w, and thence 
 along the ship’s deck; at this any number of men may be employed 
 very advantageously to produce the stroke, leaving those at the handle only 
 to return it by lifting the handle. If the ship proves leaky, and the stuffing- 
 box is thought to be an obstruction to the working of the pump, the air- 
 vessel may be taken out by drawing the wedge d, and taking out the bars R, 
 which confine it ; then after taking out the key which connects the joint- 
 piece g with the copper rod, also removing the brake, lift out the air-vessel 
 by the two screws of the stuffing-box, and fix on the joint-piece again, but 
 fix the guide-eye H in the lowest pair of holes, so that it will receive the top 
 of the copper rod, and prevent the pump-spear from having any play in the 
 slings. 
 
 In this state it acts as a common hand-pump ; but the air- 
 vessel can be restored to its place, and be ready for work, in 
 two minutes. 
 
 To prevent any of the work from being neglected from' 
 carelessness, the inventor proposes that one of the pumps 
 shall be always used to wash the ship by the hose and jet 
 every morning, which it would do much more effectually than 
 by the present mode of raising the wafer into buckets ; and 
 the force with which the jet of water is thrown would very 
 completely wash into every recess of the gun-carriages, and 
 other places where a brush cannot reach ; while by this con- 
 stant exercise the pumps would be always ready, at a mo- 
 ment’s notice, upon an alarm of fire. 
 
 17. Mr. Robert Clarke, of Sunderland, has proposed a great 
 improvement in the mode of applying men’s force to pump- 
 ing, which is worthy the consideration of seamen. It is to 
 change the posture of standing to sitting, and making the 
 action the same as that of rowing, which, besides that it is 
 by philosophers considered as the most efficacious application 
 of a man’s force, it is to seamen most particularly so from 
 their habitual practice of it. He objects to the ordinary 
 action of pumping with a brake, as the posture is weak, and 
 requires much force to preserve it. It oppresses the man by 
 overstretching his loins on one side, and incommodes respira- 
 tion by the flexure of the body on the other side. Too much 
 motion of the shoulder-joint is required, as the muscles which 
 act on the arm-bone at this joint are disproportionate to the 
 effort they must make when the arm vibrates on the shoulder- 
 joint as a centre, for the force to be communicated by the 
 hand. Besides this, the arms themselves are at one instant 
 enfeebled, by being thrown over the head, and requiring a 
 pull, and the next instant require a pushing effort, which 
 changes of direction in the exertion and restraining force are 
 too continual and rapid for long continuance ; in standing 
 the body is a continued dead weight upon the legs. 
 
 T 
 
THE OPERATIVE MECHANIC 
 
 271 
 
 The action of rowing is powerful to a surprising degree^ 
 and so well adapted to a man’s ease, that he can continue it 
 a greater length of time without fatigue than any other mode 
 of exertion ; for though the motion is large, it is made up of 
 easy motions in several joints, the velocity and resistance 
 of which suit the muscles employed. Very little sustaining 
 force is required, for the body is supported, and returns 
 unloaded to its charge ; the breathing is free. The manner 
 of carrying this into effect is very simple, the lever or brake 
 being bent at right angles at a certain pin, so that it hangs 
 straight down when it is at rest, instead of being horizontal ; 
 then to the lower extremity a rod is jointed, which is carried 
 rather in an inclined direction upwards to the seaman, w'ho is 
 seated before the pump with a rest for his feet. The rod has 
 a cross handle, to hold by both hands, and in some cases it 
 may be made long enough for two men to sit side by side on 
 the same seat; and by drawing and pushing it in the same 
 manner as rowing, the perpendicular lever is caused to vibrate, 
 and the horizontal arm or bended part, which suspends the 
 pump-spear, partakes of the motion sufficiently for pumping. 
 
 18. M. de Bonnard, speaking of the pistons of pumps, in 
 the Journal des Mines, states, that the leathers with which tlie 
 external circumference of the pistons of pumps are covered, 
 are quickly worn out by the continual friction which they 
 undergo, and the renewing of them is an object of considerable 
 expense in large mining undertakings. 
 
 They have therefore used in Saxony, ^for some years past, 
 pistons without these external leathers in sucking-pumps, 
 and to render the upper part of the piston elastic, by com- 
 posing it of pieces of wood, which expand or open when the 
 piston rises, and close when it descends. 
 
 To obtain this effect, the part of the piston which forms a bucket, is 
 composed of a system of small movable pieces of wood a a a, figures 260 
 and 261, cut obliquely, and disposed so as to cover each other nearly half 
 their breadth; a leather which covers the upper surface of each of these 
 pieces, serves to sustain them, and yet allow them sufficient play. To the 
 under part of the same, pieces of leather are attached, which aftbrd them all 
 the elasticity that is necessary. These leathers are received into slits that 
 are cut round the piston, and directed obliquely to its edges ; they are fixed 
 to the pieces of wood by nails, the extremities of which correspond with the 
 notches c cc, and to the edges of the solid part of the piston by the screws 
 ddd. By this disposition each piece of wood is movable upon a son of 
 horizontal hinge, and when the piston is raised, the weight of the water with 
 which it is charged, by opening all these pieces, causes them to press one 
 against the other, and against the sides r r of the barrel of the pump, so asl 
 not to let any of the water escape, and to produce completely the effect of 
 a pi.'.ton furnished with leather. The interior edges of each of the joints of 
 
AND MACHINIST. 2/5 
 
 the movable pieces are covered two by two with leather as at eee, fig, 261, 
 upon which the weight of the water acts as upon the pieces themselves. 
 
 All these leathers last a very long time, as well as those of 
 the suckers, because they are not exposed to any friction, 
 which only acts upon the movable pieces of wood. When 
 the piston descends, the water that raises the suckers finds 
 an easy passage, without filtering between the piston and the 
 interior of the barrel of the pump ; an effect which has this 
 additional convenience, that no dirt can be introduced into 
 the joints, which might afterwards prevent the perfect contact 
 of the different pieces. 
 
 In 1808, these pistons were tried in several mines in Saxony, 
 and were found very satisfactory. It was only observed that 
 there was some inconvenience attending the use of them w here 
 the wells w^ere much inclined ; as the pressure of the w'ater 
 above not being equal upon all the movable pieces of the 
 piston, those that were least pressed upon let some of the 
 water pass between them. These inconveniences however 
 exist only in the ordinary pistons. 
 
 In some departments pistons with springs are sometimes 
 used, which are composed of movable rubbing-pieces, that 
 are substituted for the leathers that are ordin'arily employed. 
 We know that these pistons are used with advantage in the 
 cylinders of some blowing-engines ; but in these pistons the 
 rubbing-pieces are constantly forced against the interior sur- 
 face of the cylinder by the springs . 
 
 In the piston wdth the flexible crown of WDod, which 
 M. Bonnard has described, the movable pieces of wood that 
 compose it do not rub against the interior surface of tlie 
 barrel of the pump, except when the piston ascends, being 
 then pushed by the weight of the column of water that is 
 raised, and they scarcely rub at all against the surface when 
 the piston descends. This peculiar effect assimilates this 
 piston with those that have a flexible crown of leather, or 
 a bucket, and gives it a decided advantage over pistons with 
 springs and cushions. In other departments pistons with 
 springs are sometimes used, which move in cylinders of 
 cast-iron. 
 
 These pistons are composed of four pieces of brass, aaaa, figures 2fi2 
 and 263, which are each about three centimetres in height and thickness, 
 and are pushed horizontally by two springs, bbhb. Those pieces, which 
 we shall call quadrants, in order that none of the air may escape when they 
 play under the inequalities of the cylinder in which they rise and descend, 
 are each of them something longed than a quarter of the circumference of 
 the cylinder, and towards the extremities they are reduced to half the 
 thickness. 
 
 By this mean?, these quadrants are perfectly covered at the extremitie.s, 
 
 t2 
 
THK OPERATIVE MKCIIANTC 
 
 ■27H 
 
 and prevent the passage of the air in a horizontal direction, while the springs 
 li b b I) preverrt its passage vertically. 
 
 In conclusion we shall observe, that these pistons, perfectly 
 joined, have been proved to be proper for driving air with 
 great force. We shall likewise observe, that the quadrants 
 aa a a being made of brass, and rubbing against cast-iron, 
 ought to last a very long time ; consequently, the blowing 
 here mentioned have the advantage of not requiring frequent 
 repairs. 
 
 19. The following piston, described and recommended by 
 Belidor, seems as perfect as the nature of things will allow. 
 We shall therefore describe it in the author’s own words, as 
 a model which may be adopted with confidence in the greatest 
 works. 
 
 “ The body of the piston is a truncated metal cone, (fig. 264,) having 
 a small fillet at the greater end. Fig. 265 shows the profile, and fig. 266 
 the plan of its upper base, where appears a cross-bar D D, pierced with an 
 oblong mortise E for receiving the tail of the piston-rod. A band of thick 
 and uniform leather A A (figs. 265 and 267) is put round this cone, and 
 secured by a brass hoop B B, firmly driven on its smaller end, where it is 
 previously made thinner to give room for the hoop. 
 
 “ This piston is covered with a leather valve, fortified with metal plates G G 
 (fig. 268.) These plates are wider than the hole of the piston, so as to rest 
 on its rim. There are similar plates below the leathers, of a smaller size, that 
 they may go into the hollow of the piston ; and the leather is firmly held 
 between the metal plates by screws H H, which go through all. TTiis is 
 represented by the dotted circle J K. Thus the pressure of the incumbent 
 column of water is supported by the plates G G, whose circular edges rest 
 on the brim of the water-way, and thus straight edges rest on the cross-bar 
 D D of figs. 265 and 266. This valve is laid on the top of the conical box 
 in such a manner that its middle F P rests on the cross-bar. To bind all 
 together, the end of the piston-rod is formed like a cross, and the arms M N 
 (fig. 269) are made to rest on the diameter F F of the valve, the tail E F 
 going through the hole E in the middle of the leather, and through the 
 mortise E of the cross-bar of the box, as well as through another bar, Q R, 
 (figs. 267 and 268,) which is notched into the lower brim of the box. A key 
 V is then driven into the hole I, in the piston-rod ; and this wedges all fast. 
 The bar Q R is made strong ; and its extremities project a little, so as to 
 support the brass hoop B B, which binds the leather band to the piston-box.’'^ 
 
 This piston has every advantage of strength, tightness, and 
 large water-way. The form of the valve (which has given it 
 the name of the butterfly-valve) is extremely favourable to 
 the passage of the water ; and as it has but half the motion 
 of a complete circular valve, less water goes back while it is 
 shutting. 
 

 From 1*(U to FFF 
 
 FL.34. 
 
I 
 
 I 
 
 1 
 
 i 
 
 ! 
 
 ii 
 
AND MACHINIST. 
 
 FIRE-ENGINES. 
 
 When fire breaks out in a crowded neighbourhood, it car- 
 ries with it such devastating effects, that any individual who 
 has seriously turned his attention to the constructing of an 
 engine that is in the least calculated to check its progress, 
 must ever be considered as deserving of our praise. Those 
 who have most beneficially directed their attention this way 
 are Messrs. Newsham and Rowntree, whose engines we shall 
 now proceed to describe. 
 
 1. A perspective view of Mr. Newsham’s fire-engine, ready 
 for working, is represented in fig. 270 . 
 
 It consists of a cistern A B, about three times as long as it is broad, 
 made of thick oaken planks, the joints of which are lined with sheet copper, 
 and easily movable by means of a pole and cross-bar C w, the fore part of 
 the engine, which is so contrived as to slip back under the cover of the 
 cistern and on four solid wheels, two of which are seen at D and E. The 
 hind axle-tree, to which the wheel E and its opposite are fixed, is fastened 
 across under the bottom of the cistern ; but the fore axle-tree, bearing the 
 wheel D, &c. is put on a strong pin or bolt, strongly fastened in a hori- 
 zontal situation in the middle of the front of the bottom of the cistera, by 
 which contrivance the two fore- wheels and tlie axle-tree have a circular 
 motion round the bolt, so that the engine may stand as firm on rough or 
 sloping ground as if it were level. 
 
 Upon the ground next to the hind part of the engine may be seen a 
 leather pipe F, one end of which may be screwed on and off upon occa- 
 sion to a brass cock at tlte lower end of the cistern ; the other end is 
 immersed in water, supplied by a pond, fire-plug, &c. and the pipe 
 becomes a sucking-pipe for furnishing the pump of the engine by its work- 
 ing, without pouring water into the cistern. To the hind part of the cistern 
 is furnished a wooden trough G, with a copper grate for keeping out 
 stones, sand, and dirt, through which the cistern is supplied with w’ater 
 when the sucking- pipe cannot be used. The fore part of the cistern is 
 also separated from the rest of its cavity by another copper grate, through 
 which water may be poured into the cistern. Those that work the pumps 
 of this engine move the handles, visible at the long sides, up and down, and 
 are assisted by others w’ho stand on two suspended treadles, throwing their 
 weight alternately upon each of them, and keeping themselves steady, by 
 taking hold of two round horizontal rails HI, framed into four vertici 
 stands which reach the bottom of the cistern, and are well secured to its sides. 
 
 Over the hind trough there is an iron handle or key K, serving to open 
 or shut a cock placed under it on the bottom of the cistern, the use of 
 which we shall explain in the sequel of this article. L is an inverted 
 pyramidal case which preserves the pumps and air-vessels from damage, 
 and also supports a wooden frame M, on which stands a man, who, by 
 raising or depressing, and turning about the spout N, directs the stream of 
 water as occasion requires. This spout is made of two pieces of brass pipe, 
 each of which has an elbow ; the lower is screwed over the upper end F, 
 (fig. 271,) of the pipe that goes through the air-vessel, and the upper part 
 screws on to the lower by a screw of several threads, so truly turned as to 
 be water-tight in every direction. The conic fonn of the spouting pipe 
 serves for wiredrawing the water in its passage through it, which occasions 
 a friction that produces such a velocity of the jet as to render it capable of 
 
THE OI’KIIaTIVE MECHANIC 
 
 278 
 
 breaking windows, 8cc. whilst the valves and leather pipes of the engine 
 have sufficient water-way to supply the jet in its greatest velocity. Leather 
 pipes of considerable length may be screwed at one end of the nozle of 
 the engine, and furnished at one end with a w'ooden or brass pipe for 
 guiding the water into the inner parts of houses. 
 
 Between the pyramid-box L, and the fore end of the engine, there is a 
 strong iron bar O, lying in a horizontal position over the middle of the 
 cistern, and playing in brasses supported by two wooden stands ; one of 
 which, P, is placed between the two fore stands of the upper rails, and the 
 other is hid in the enclosure ever the hind part. Upon proper squares of 
 this bar are fitted, one near each end, two strong brass bars, which take hold 
 of the long wooden cylindrical handles, by means of which the engine is 
 worked ; and the treadles by which they are assisted are suspended at each 
 end by chains in the form of a watch-chain, and receive their motion jointly 
 with the handles, that are on the same side, by means of two circular 
 sectors of iron fastened together, and fixed upon proper squares of the 
 middle horizontal bar; the two fore ones may be seen at Q; the two hind 
 ones, represented upon a large scale in fig. 272, differ from the former only 
 in thickness, for the fore sectors are made to carry only one chain each, 
 fastened by one end to their upper part, and by the lower end to the 
 treadles ; whereas the sole of the two hind sectors is wide enough to carry 
 two chains each ; one set fastened like those of the fore ones for the motion 
 ,of the treadles ; and the other two chains are fastened by their lower ends 
 to the lower part of these sectors, and by their upper ends to the top of 
 the piston-bars, in order to give them motion. See fig. 271, in which the 
 hind sectors and their apparatus are represented as they would appear to a 
 person standing between the two fore wheels, and looking at the hind part 
 of the engine. 
 
 The square over the letter A is the section of the middle bar, on which, 
 right over the two barrels, are placed the two sectors B C A and D E A, 
 forged together. F G H K and fghk are the two piston-rods ; and the 
 openings between the letters G H and g h, are the spaces through which 
 the hind parts of the tw’o treadles pass. L and M represent two strong 
 studs, rivetted on the other side of the bars on which they are placed ; and 
 to each of these is fastened a chain like a watch-chain, and fixed by their 
 upper ends to the upper extremities D and B of the iron sectors, by which 
 they are drawn up and down alternately. These sectors give also an alternate 
 motion up and down to the piston-rods, by means of two other chains less 
 white in the figure, in order to distinguish them from the others ; these are 
 fastened by their lower ends to the lower extremities of the sectors E and 
 C, and their upper ends, terminating in a male screw, are made tight to the 
 piston-rods at F and /, by two nuts. 
 
 The shape of the piston-rods, and the size and situation of the chains 
 that give them motion, are so contrived, that the vertical axis of the pistons 
 is exactly in the middle of the breadth of the perpendicular part of the 
 chains, and the upper part of the piston-rod taken together. P Q repre- 
 sents one of the two cross-bars through the ends of which pass the handles 
 to which the men apply their hands when they work the engine ; these 
 cross-bars are fitted on the middle bar at some distance from the sectors. 
 
 The other parts of this useful engine may be understood by the help of 
 fig. 271, which represents a vertical section taken through the middle line 
 of the hind part of the engine, as also the section of the air-vessel, and that 
 of one of the barrels, and likewise the profiles of the hind sectors, and 
 several other parts. A B is the section of the bottom of the cistern, and 
 C that of the hindmo:^ axle-tree. DE is the vertical section of a strong 
 
AND MACHINIST. 
 
 279 
 
 piece of cast brass or hard metal, so worked as to have a hollow in it, 
 represented by the white part, and fixed to the bottom of the cistern; tliis 
 reaches from the opening D, through the cock W, and afterwards divides 
 itself into two branches, so as to open under the two barrels ; one of these 
 branches is exhibited in the figure, and the other is exactly behind this. 
 Through this channel, which may be called the sucking-piece, water is con- 
 veyed to the pumps by the pressure of the atmosphere, either from the 
 cistern itself, or from any place at a distance, by means of the leather pipe 
 F, fig. 273, which screws on to the sucking-piece at D, fig. 271, under the 
 hind trough Z, the grate of which is represented by the horizontal strokes, 
 F G represents the vertical section of another piece of ca'A brass or hard 
 metal, that may be called the communication-piece, having two hollows for 
 conveying the water from under the pistons to the two openings of the 
 flanch of the air-vessel ; one of these hollows appears in the figure ; the other 
 lies exactly behind this, though not in a parallel direction. Between the 
 section of the sucking-piece D E, and that of the communication-piece F G, 
 may be observed the section of one of the plates of leather, which makes 
 all tight, and forms one of the two sucking-valves, of which there is another 
 just behind this, under the other barrel. R S T is the section of the copper 
 air-vessel, and TV that of the conduit-pipe; this vessel is screwed on to 
 the hind part of the communication-piece, and at fop is fastened by a collar 
 of iron to a cross piece of timber. 
 
 Between the flanch of the air-vessel and the communication-piece, may 
 be observed the section of one of the plates of leather, making all tight, 
 and sciewing one of the two forcing valves, of which there is another just 
 behind this, exactly over the other opening of- the communication from the 
 air-vessel. These valves are loaded with a lump of cast-iron or lead, having 
 a tail or teat let through the flap of the valve, and cross pinioned under it ; 
 and it is to be observed, that though both the valves are represented open 
 in the figure, they are never both open at the same time ; for when the 
 engine is not at work, they are closed dowm by the weights on their upper 
 surfaces ; and when the engine works, two are shut, and the other two are 
 alternately opened by the motion of the pistons and the action of the atmo- 
 sphere, together with the reaction of the air contained in the air-vessel. 
 
 H I is the section of one of the barrels of the two pumps, which are both 
 sucking and forcing ; as is evident from the position of the valves and the 
 structure of the pistons, each of which is composed of two iron plates, of 
 two wooden trenchers, and of two flat pieces of leather turning one up and 
 the other down. L K represents one of the piston-rods edgewise, behind 
 which is one of the chains, the top screw of which, K, can only be seen. 
 M is the end of the middle bar, and N a section of the hindmost of the two 
 middle stands which support the middle bar. O represents the end of the 
 profile of one of the treadles, passing through the rectangular holes of the 
 piston-rods, as in fig. 272. The weight on these treadles brings them and 
 the piston-rods down alternately, and they are raised up again by the help 
 of the other set of chains, one of which may be seen edgewise in this figure, 
 placed on the sole of one of the sectors, &c. see fig. 272. 
 
 P Q is part of the cross-bars which carry the handles, seen edgewise, 
 and X Y represents an iron handle, by the help of which the cock W may be 
 placed in the several situations requisite for the use of the engine. The 
 mechanism may be understood by figs. 275, 276, and 277, which represent 
 the horizontal section of it, in three different situations. It has three holes, 
 which are left white in these figures. In fig. 275, the position of the cock 
 is represented when the handles X Y or K are in a direction parallel to D F>, 
 or to the middle bar, as in figs. 270 and 271. In this position the w-ater 
 supplied by the sucking-piece enters at D, and proceeds directly through 
 
280 
 
 THE OPERATIVE MECHANIC 
 
 the cock W to the 'alve under the two pistons ; and there is now no cora- 
 municdtion from the barrel with the cavity of the cistern. 
 
 In tig. 276, we have the position of a cock when the handle X Y is turned 
 one quarter of a revolution towards the eye from the last-mentioned situa- 
 tion, in which case there is no communication from the barrels with the 
 outer extremity of the sucking-piece, but the water poured into the fore and 
 hind trough, and passing from thence into the cavity of the cistern, enters 
 the cock sideways at W, and turning at right angles through the cock 
 towards E, proceeds to the barrels of the pumps. Fig. 277*^ represents the 
 cock W when the handle is placed diametrically opposite to its last situa- 
 tion, in which case there is no communication from the under side of the 
 barrels with the cavity of the cistern or the outward end of the sucking-piece ; 
 but this situation affords a communication from the cavity of the cistern 
 with the outside of the engine, and the water left in the cavity of the 
 cistern may by this means be employed when the engine has done working. 
 These engines are made of five or six different sizes. 
 
 The principles on which this engine acts, so as to produce 
 a continued stream, are obvious : the water being driven into 
 the air-vessel, as in the operation of common sucking and 
 forcing pumps, will compress the air contained in it, and 
 proportionably increase its spring, since the force of the 
 air’s spring will be always inversely as the space which it 
 possesses 3 therefore when the air-vessel is half filled with 
 water, the spring of the included air, which in’ its original 
 state counterbalanced the pressure of the atmosphere, being 
 now compressed into half the space, will be equal to twice 
 the pressure of the atmosphere; and by its action on the 
 subjacent water will cause it to rise through the conduit- 
 pipe, and play a jet of 32 or 33 feet high, abating the effect 
 of friction. When the air-vessel is two-thirds full of water, 
 the space which the air occupies is only one-third of its first 
 space ; therefore its spring being three times as great as that 
 of the common air, will project the water with twice the 
 force of the atmosphere, or to the height of 64 or 66 feet. 
 In the same manner when the air-vessel is three-fourths full 
 of water the air will be compressed into one-fourth of its 
 original space, and cause the water to ascend in air with the 
 force of three atmospheres, or to the height of 96 or 99 feet, 
 &c. as in the following table ; 
 
 Height 
 of the 
 water. 
 
 I 
 
 Height 
 
 Proportion 
 
 Height 
 
 of the 
 
 of the 
 
 to which the 
 
 compressed air. 
 
 air’.s spring. 
 
 water will rife. 
 
 i 
 
 h 
 
 2 
 
 33 feet. 
 
 3 
 
 66 
 
 i 
 
 4 
 
 99 
 
 1 
 
 5 
 
 5 
 
 132 
 
 f 
 
 6 
 
 165 
 
 T 
 
 7 
 
 198 
 
 
 8 
 
 231 
 
 
 9 
 
 264 
 
 V5 
 
 10 
 
 297 
 
AND MACHINIST. 
 
 281 
 
 2. The fire-engine by Rowntree is a double force-pump, 
 of a peculiar construction, similar in its action to the beer- 
 engine, but as it is on a much larger scale, its constructions 
 are of course varied. 
 
 In this engine, figs. 278 and 279 are two elevations at right angles to 
 each other, of the external part of the engine, mounted on four W'heels. 
 Figs. 280 and 281 are two sections perpendicular to each other of the body 
 of the engine or pump ; figs. 282 and 283 are parts of the engine. The 
 same letters are used as far as they apply in all the figures ; A A A 
 figs. 280 and 281, is a cast-iron cylinder truly bored, 10 inches diameter 
 and 15 long, and having a flanch at each end whereon to screw two covers, 
 with stuffing-boxes a a, in their centres, through which the spindle, B B, of 
 the engine passes, and being tight packed with hemp round the collar, 
 makes a tight joint; the piston D is affixed to the spindle within the 
 cylinder, and fits it tight all round by means of leathers; at E, fig. 281, a 
 partition, called a saddle, is fixed in the cylinder, and fits against the back 
 of the spindle tight by a leather. 
 
 We have now a cylinder, divided by the saddle E and piston into 
 two parts, whose capacity can be increased and diminished by moving the 
 piston, with proper passages and valves to bring and convey the water ; 
 this will form a pump. These passages are cast in one piece with the 
 cylinder ; one, d, for bringing the water, is square, and extends about 
 one-third round the cylinder ; it connects at bottom with a pipe e ; at its 
 two upper ends it opens into two large chambers f g, extending near the 
 whole length of the cylinder, and closed by covers, h h, screwed on ; ik are 
 square openings (shown by dotted squares in fig. 280) in the cylinder 
 communicating with the chambers ; I m in f g are two valves closing the 
 ends of the curved passage rf, and preventing any water returning down 
 the passage d ; no are two passages from the top of the cylinder to convey 
 away the water ; they come out in the top of the cylinder, which, together 
 with the top of the chambers f g^ form a flat surface, and are covered by 
 two valves, p q, to retain the water which has passed through them. A 
 chamber, K, is screwed over these valves, and has the air-vessel k, figs. 278 
 and 279, screwed into its top ; from each side of the chamber a pipe, wwj 
 proceeds, to which a hose is screwed, as shown in fig. 280. Levers, 
 are fixed to the spindle at each end, as shown in fig. 279, and carry the 
 handles H H, by which men work the engine. When the piston moves, 
 as shown by the arrow in fig. 281, it produces a vacuum in the chamber 
 and that part of the cylinder contiguous to it, the water in the pipe e then 
 opens the valve m, and fills the cylinder. 
 
 The same motion forces the water contained in the other part of the 
 cylinder through the valve into the chamber K, and thence to the hose 
 though the pipe w ; the piston being turned the other way reverses the 
 operation with respect to the valves, though it continues the same in itself. 
 The pipe e is screwed by a flanch to an upright pipe P, fig. 282, con- 
 nected with another square iron pipe, fastened along the bottom of the 
 chest of the engine; a curved brass tube, G, comes from this pipe through 
 the end of the chest, and is cut into a screw to fit on the suction-hose 
 when it can be used ; at other times a close cap is screwed on, and another 
 brass cap at H, within the chest, is screwed upwards on its socket, to open 
 several small holes in it, and allow the water to enter into the pipe ; in this 
 case the engine-chest must be kept full of water by buckets. The valves 
 aie made of brass and turn upon hinges. Tlie principal advantage of 
 Ahe engine is the facility with which it is cleared from any sand, gravel. 
 
282 THE OPERATIVE MECHANIC 
 
 or otlier obstructions, wliich a fire-engine will always gather when at 
 work. 
 
 The chambers being so large, allow sufficient room to lodge a greater 
 quantity of dirt than is likely to be accumulated in the use of the engine at 
 any one fire, and if any of it accidentally falls into the cylinder, it is gently 
 lifted out again into the chambers, by the piston, without being any obstruc- 
 tion to its motion ; to clear the engine from the dirt, two circular plates of 
 five inches diameter, are unscrewed from the lids k k, of the chambers f 
 and when cleaned are screwed on again; these screw-covers fit perfectly 
 tight without leather, and can be taken out, the engine cleared, and enclosed 
 again in a very short time, even when the engine is in use, if found 
 necessary. 
 
 The two upper valves p 7, and chamber K, can also be cleaned with 
 equal ease, by screwing out the air-vessel kky fig. 278, which opens an 
 ^erture of five inches, and fits air-tight, without leather, when closed. 
 Ine valve may be repaired through the same openings. The use of the 
 air-vessel, k k, figs. 278 and 279, is to equalize the jet from the engine 
 during the short interm ittance of motion at the return of the piston-stroke ; 
 this it does by the elasticity of the compressed air within it, which forces 
 the water out continually, though not supplied quite regularly from the 
 engine. 
 
 The engine from which the drawing was taken, was con- 
 structed for the Sun Fire Insurance Company, in London, and 
 from some experiments made by their agent, Mr. Samuel 
 Hubert, appears to answer every purpose. 
 
 JACKS. 
 
 The jacks wdiich we purpose here to describe are simple 
 machines used for raising heavy weights. 
 
 Fig. 341 represents the common or simple hand jack ; a block of wood 
 about two feet six inches long, 10 inches broad, and six inches wide, is per- 
 forated with a square hole or mortise through it lengthwise for the recep- 
 tion of an iron rack B. This rack is formed with a double claw or horn at 
 its upper end. A small pinion C is made to engage in the teeth of the rack. 
 The axis of the pinion is supported in iron plates bolted to each side of the 
 block, and one end of the axis projects through the side plate, with a square 
 to receive a winch or handle, which, being turned round, the pinion ele- 
 vates the rack B in the mortise, and raises the claw or horns up to the load 
 to which it is applied. To prevent the weight of the load running the pinion 
 back, the handle is detained by a hook or link a, fastened to the outside of 
 the block. 
 
 When a greater power is required than the simple rack and pinion are 
 capable of exerting, a combination of wheel-work is used, as shown in the 
 same figure, where A A is the block of wood, which in this case is made 
 sufficiently wide to contain the cog-wheel F, fixed to the pinion C, which 
 acts in the teeth of the rack B. G is a second pinion of four leaves, work- 
 ing in the wheel F ; and the axis of this pinion projects through the side of 
 the block for the winch H to be fixed on it. The block A A is made in two 
 halves, and the recess for the wheel F, and the pinion G, is cut out in one 
 of the halves ; the other, being laid fiat against it, supports the front pivots 
 
, TMTE ® JFmE 
 
 FI. 36 . 
 
AND MACHINIST. 
 
 283 
 
 of the wheel and pinions. The two halves are bound together by strong 
 iron hoops b b, driven over the outside. The rack has a claw N, at its lower 
 end, projecting out sideways through an opening or slit cut through in the 
 front half of the block. This claw can be introduced beneath a stone which 
 lies nearly flat upon the ground, and which consequently could not be acted 
 upon by the claw on the top of the rack. To prevent the rack descending 
 when it has a load upon it, the small click a drops into its teeth, but clears 
 it in going up ; when it is not required to detain the rack, this click can be 
 turned out of the way sideways. 
 
 Fig. 342 is a screw jack. The block of wood A A is perforated nearly 
 its whole length with a hole sufficiently large to allow the screw B to move 
 up and down without touching. The screw passes through a nut n, fixed into 
 the top of the block A ; and if the screw is turned round, it must rise up through 
 the nut, and elevate the claw F. This claw is fitted on the top of the screw 
 with a round collai, which allows the screw to turn round without turning 
 the claw ; and the claw N, which projects through a groove or opening 
 made in the side of the block, is fitted to the screw with a smaller collar. 
 The bottom of the block has four short points to prevent the machine slip- 
 ping when used upon hard ground. To give motion to the screw, the 
 lower half of it is formed into a square, and a worm-wheel C is fitted upon 
 the square. The teeth of this wheel are engaged by a worm on the axis of 
 the winch H, and plates of iron, a b, are bolted on each side of the block, 
 near the middle of its height, to carry the ends of the axis of the winch and 
 of the worm which is concealed by the worm-wheel C. When the winch is 
 turned round, it causes the wheel C to revolve by the action of the worm in its 
 teeth ; and as the wheel is fitted on the square part of the screw, it compels 
 it to turn v/ith it, but at the same time allows the screw to move up and down. 
 
 Jacks have been also constructed upon the hydrostatic 
 principle discovered by Pascal, and which has been applied 
 to practice by the late Mr. Bramah, in this and various 
 other useful machines. 
 
 CRANES. 
 
 Cranes are certain simple machines in which either the 
 wheel and axle, or wheel and pinion, are introduced, to effect 
 the raising of heavy loads, such as the loading or unloading 
 of shipping at the quays or wharfs, or the raising or lowering 
 goods to and from chambers or warehouses. 
 
 Various modes have been adopted to turn the wheel, or 
 that part of the machine which is applied to the same pur- 
 pose, by introducing long staves into the axle, by which 
 it acquires the name of a capstan, or windlass ; or by a rope 
 passing over the wheel, and putting it and the axle in motion 
 by friction. Other methods have been adopted, such as form- 
 ing the wheel hollow, and causing it to revolve by means of 
 labourers inside of it, walking up its sides, which consequently 
 descends beneath their weight ; or by forming it into a plat- 
 form, lying in a slanting direction, and the labourers pushing 
 
284 
 
 THE OPERATIVE MECHANIC 
 
 against a fixed arm, which forces the platform or wheel roiind 
 under their feet. 
 
 Most of the cranes constructed with the wheel and axle 
 occupy too ^uch space, which is of importance, and conse- 
 quently, where cranes are in general use, have been super- 
 seded by the wheel and pinion, which is of a more compact and 
 convenient construction. The wheel and pinion is generally 
 accompanied with a ratchet-wheel and pall, or some other me- 
 thod of locking the handle, so that should the labourer desist 
 from his exertion, the load may not return to the place 
 whence it has been raised. 
 
 The frame-work, or that part of the crane which does not 
 immediately operate to raise the load, is divided into three 
 part,s, the post, the jib, and the stay. The post is the upright 
 piece, almost universally made to turn on a centre ; the jib is 
 the arm extending from the upper part of the post, and in 
 some cases is horizontal, but more frequently at an angle to 
 the horizon ; and the stay is that piece which supports the 
 jib, reaching from the lower part of the post to nearly the 
 extremity of the jib. 
 
 The most simple form of the crane is that commonly used 
 in stone and timber wharfs for unloading vessels, for which 
 purpose it is well adapted, its power being very great. It 
 has a frame consisting of a strong beam supported hori- 
 zontally at 10 or 12 feet from the ground, on the top of 
 several vertical posts very firmly fixed in the ground, and 
 securely braced with stays in every direction. At the ex- 
 tremity of the horizontal beam the upper part of the jib is 
 supported, the lower pivot resting on a post in the ground. 
 The jib, or gibbet, as it is called, from a resemblance to that 
 machine, is a triangular frame of wood, one side being per- 
 pendicular, and supported on pivots at the top and bottom, 
 so that the whole moves round on these as a vertical axis of 
 motion. Near the upper end of the perpendicular post, a 
 beam proceeds, forming the upper side of a triangle, while 
 the third side is a brace, extended from the foot of the per- 
 pendicular, to support the upper piece. From the extremity 
 of the latter, the burden is suspended by a rope passing over 
 a pulley ; the other end of the rope is coiled round a vertical 
 roller, or capstan, turning on pivots, one supported by the 
 horizontal beam first mentioned, and the other on a post in 
 the ground. The capstan is turned round by means of long 
 horizontal levers fixed to it, at which a great number of men 
 may be employed to push them round, or in some cases they 
 are drawn by horses. As the levers admit of a very great 
 
AND MACHINIST, 
 
 285 
 
 length in proportion to the diameter of the windlass on which 
 the rope coils, the power of this simple crane is very con- 
 siderable, and may be doubled by a pair of blocks or pullies 
 at the jib. When the burden is raised to a sufficient height, 
 by turning the capstan, the jib, being swung round on its 
 pivots, will convey the load into a cart or waggon placed on 
 shore by the side of the crane. 
 
 Another kind of crane, which is equally common with the 
 above, but used for lighter burdens, has tlie same jibs, as 
 indeed most cranes have ; but the windlass, or barrel for the 
 rope, is placed horizontally, and has a large vertical wheel 
 fixed upon it. This is made of two wheels fixed on an axis 
 at a distance apart, and united by boards, so as to form 
 a large hollow cylinder or drum. Several men get into this 
 wheel, and by constantly walking upwards on the inside, 
 give it a tendency to revolve, and wind up the rope on the 
 barrel. It is surprising, that so imperfect, this should have 
 been so universally adopted as it was, till within these few 
 years. Even when the wheel is sixteen feet in diameter, the 
 labourers within cannot walk so far up it, from the perpen- 
 dicular, as to have any effective leverage to turn it round ; 
 though they are always exposed to danger, and frequently 
 meet with most shocking and fatal accidents, from slipping 
 down in the wheel, or from being overpowered by the load ; 
 in this case, the wheel runs back with an accelerating velocity, 
 and the people are thrown about it in a most dreadful manner. 
 From these defects of the common construction, skilful me- 
 chanicians have devised cranes that are not only more safe, 
 but more powerful in their operation, than the common 
 walking-crane. Some of the best of these will be described 
 in the present article. 
 
 Mr. Padmore, many years ago, contrived to prevent the 
 danger attending the use of the construction last described, 
 by putting a ring of cogs all round the outside of the great 
 wheel, and applying a trundle provided with winches to turn 
 it. By this addition, the power was increased in proportion 
 to the number of cogs in the wheel to the number of staves 
 in the trundle ; and in order to prevent the wheel from run- 
 ning back by the force of the weight, should the man within 
 it slip, or leave off walking, he added a ratchet-wheel to the 
 end of the trundle. Tv/o winches being fixed to the ends of 
 the axis of the trundle, gave the people attending the crane 
 the means of assisting the man in the -wheel, when the load 
 rendered it necessary. On the axis of the trundle is likewise 
 fixed a wooden wheel provided with a brake or gripe, which 
 
286 
 
 THE OPERATIVE MECHANIC 
 
 could be forcibly pressed on the circumference of the wheel 
 by a lever, to cause such a friction as would prevent the 
 weight from descending too rapidly. By this means, heavy 
 goods may be raised or let down at pleasure, without any 
 danger of injuring the men in the crane. This contrivance is 
 ingenious ; but the rapid motion of the circumference of the 
 large walking wheels, in most cases, rendered it inapplicable, 
 unless a smaller cog-wheel was fixed upon the same axis with 
 the walking-wheel. 
 
 A crane to be turned by winches, was contrived by the 
 late Mr. Ferguson, which has three trundles, with different 
 numbers of staves. Any one of these may be applied to the 
 cogs of a liorizontal wheel, mounted on an upright axle, round 
 which is coiled the rope for drawing the weight. This wheel 
 has 96 cogs ; the largest trundle 24 staves, the next 12, and 
 the smallest six ; so that the largest revolves four times for 
 one revolution of the wheel, the next eight, and the smallest 
 sixteen. The winch is occasionally fixed on the axis of 
 either of these trundles for turning it, and is applied to one 
 or the other, according as the weight to be raised is smaller 
 or larger. There is also a fourth trundle acting in the teeth 
 of the great wheel, and on its axis is a brake and ratchet- 
 wheel. While the load is drawing up, the teeth of the 
 ratchet-wheel slip round below a catch which falls into them, 
 and prevents the crane from turning backward, thus detaining 
 the weight in any part of its ascent, if the man who works at 
 the winch should accidentally quit his hold, or wish to rest 
 himself before the weight is completely raised. Making 
 a due allowance for friction, a man may raise, by such a crane, 
 from three to twelve times as much in weight as would 
 balance his effort at the winch, viz. from 90 to 360 lbs., 
 taking the average labour. 
 
 Many other constructions of wheel-work are in common 
 use for cranes. When they are turned by a winch, it is 
 proper to apply a fly-wheel to the axis of it, both to equalize 
 the efforts of the labourer who turns it, and in case he acci- 
 dentally lets go the handle, to prevent the load from running 
 down so quickly as to endanger any thing. It is convenient 
 to have several different powers to a crane of this kind, to 
 adapt it for the different burdens to be raised ; this is best 
 done by employing a train of several wheels, each turned by 
 a pinion smaller than itself. Thus, suppose the barrel on 
 which the rope or chain winds to be 12 inches in diameter, 
 and has a cog-wheel of 96 teeth fixed on the end of it ; this 
 is turned by a pinion of 12 leaves; on the same axis with 
 
AND MACHINIST. 
 
 287 
 
 this is a wheel of 3*2 teeth, moved by a pinion of eight, 
 actuated on a third axis, which should carry the fly-wheel. 
 A winch of one foot radius can be applied to any of these 
 three axes in the crane, and will give three different powers. 
 Thus, if it is applied to the gudgeon of the barrel, it will 
 double the power of the balance, because the winch describes 
 a circle which is twice as large as the barrel on which the 
 chain winds ; if the winch is fixed on the end of the axis 
 which carries the pinion of 12, and the wheel of 32, it 
 will give the labourer a purchase of 16 times ; and lastly, 
 when the winch is applied to the pinion of eight, his efforts 
 will be multiplied 64 times. This simple mechanism is ren- 
 dered very complete by fixing a fly-wheel upon the axis of 
 the pinion of eight, to prevent all accidents ; for which pur- 
 pose it is more effective than a ratchet-wheel, and requires no 
 attention. The spindles of all the pinions are made capable 
 of sliding endwise, for the purpose of disengaging the wheels 
 from each other at pleasure, that when the wheels are not 
 employed, there may be no unnecessary friction in turning 
 them round. 
 
 The gibbet of a crane is a very principal member, as we 
 have before explained ; but in its common construction, it 
 has some defects. The rope by which the burden is raised, 
 passes exactly over the gudgeon of the vertical beam of the 
 jib, and is confined between two small vertical rollers, in order 
 that it may always lead fair wdth the pulley or sheave at the 
 extremity of the jib. According to this construction, when- 
 ever the jib turns round its axis, the rope is bent so as to 
 form an angle more or less acute, which causes a great in- 
 crease of friction, and produces a continual effort to bring 
 the arm of the jib into a parallel position to the inner part of 
 the ropes. These inconveniences may appear to be trifling, 
 but, in actual practice, they are of no small importance ; for 
 they necessarily require a much greater degree of power in 
 raising goods, and the application of a constant force to keep 
 the jib in the position that may be requisite ; while the par- 
 tial stress which is exerted on only a few strands of the rope, 
 whilst bent into an acute angle, destroys it in a very short 
 time. 
 
 A simple construction of the jib, invented by Mr. Bramah, 
 obviates all these defects, and at the same time possesses the 
 very desirable property of permitting the jib, of what is termed 
 a wharf or landing crane, to revolve wholly round its axis, 
 and to land goods at any point of the circle described by the 
 arm of the jib. 
 
288 
 
 THE OPERATIVE MECHANIC 
 
 The simplest form of this contrivance is shown in fig. 343, in which A A 
 represents (the jib of a warehouse-crane projecting from a wall. It has, as 
 usual, a pulley at the extremity, from which the goods are suspended. The 
 improvement consists in placing a pulley at S, to conduct the rope down 
 through the axis of motion of the jib, the collars or rings a a, on which it 
 swings, being perforated for the purpose. The rope afterwards passes unaer 
 a pulley 6, which conducts it into the house to the crane or machine by 
 which the weight is elevated. The pulley b may be placed between the 
 collars a a, and then there will be no necessity for a perforation of the lower 
 pivot of the jib. When the jib is required to describe a complete circle, 
 instead of the two brackets at a a, fixed to the wall, a cast-iron pillar is used 
 to support the jib, the collars a a fitting upon it; the pillar is hollow, to 
 admit the rope through it, and is firmly fixed in a vertical position, by a 
 plate cast on the lower end of it, and screwed down on the timber of the 
 wharf. Beneath these beams, there is another pulley in place of 6, to con- 
 duct the rope to the crane. 
 
 Fig. 344 represents a crane mounted on four trucks, to be capable of 
 removal from place to place. It was employed on Ramsgate-pier, for lifting 
 stones used in the building, and is extremely well adapted for such a situ- 
 ation, as it requires no fixture, and will lake up a weight of four tons with 
 four men, which is sufficient power for such purposes. It was designed and 
 executed by Mr. Peter Kier, by order of the trustees for the management 
 of the harbour at Ramsgate. Its base consists of a cast-iron frame marked 
 A B, nine feet seven inches square, and two tons weight, supported on four 
 cast-iron wheels b 6, one pair of which is fixed on a common axle, which 
 moves round on a centre fixed to one side of the frame. This axle has an 
 arm projecting across beneath the frame to the opposite side, where a rack, 
 or segment of a wheel, is fixed on it, as shown at c, engaging a pinion r, 
 shown before the rack, on the top of whose axis a winch is applied at d. 
 Now, by turning this pinion, it twists the wheels round upon the centre, to 
 steer the crane when moving from place to place. A vertical cast-iron shaft 
 marked D F, weighing 23 cwt., is erected on the centre of the iron frame, 
 and is supported by oak braces E E, stepped into boxes cast out of the iron 
 frame A B, at its angles, so as to form a very strong perpendicular column, 
 round which axis the whole crane traverses. The weight of the framing and 
 wheel-work is supported by a steel pivot, or gudgeon, on the top of the 
 shaft F, and is guided by a collar embracing the shaft at I. The framing 
 of the jib, or movable part of the crane, consists of a long beam G H, bearing 
 the pulley G at the extremity, resting on the pivot of the upright pillar in 
 the middle, and the other end supporting the frame for the wheel-work 
 L M N ; into this beam are framed two uprights Q Q, suspending the plat- 
 form I K, on which men \^^ho work the crane stand. It is braced by a 
 diagonal stay J P, and a cross piece R, to prevent its bending. 
 
 Mr. Bramah's ingenious hydrostatic principle of gaining 
 a great power is applicable in several ways to the raising of 
 heavy weights, and has been frequently employed in powerful 
 cranes. In these the power is not obtained by wheel-work, 
 pullies, or any other ordinary mechanical powers, but on the 
 principle of the experiment called the hydrostatic paradox, 
 which has been known for ages ; but the application of its 
 powers to useful purposes is due to Mr. Bramah. 
 
 The simplest form is, for a machine to raise a heavy weight 
 
JA€:K§ &C. (C .RASHES 
 
 From 341 to 3 to 
 
 Fl.46. 
 
 9 - 
 
AND MACHINIST. 
 
 to a small height. A metallic cylinder, sufficiently strong, 
 and bored truly cylindrical within, has a solid piston fitted 
 into it, which is made perfectly water-tight, by leather pack- 
 ing round its edge, or other means used in hydraulic engines. 
 The bottom of the cylinder must be made sufficiently strong 
 with the other parts of the surface, to resist the greatest 
 strain which can ever be applied to it. In the bottom of the 
 cylinder is inserted the end of the small tube, the aperture of 
 which communicates with the inside of the cylinder, and 
 introduces water or fluids into it ; the other end of the pipe 
 communicates with a small forcing-pump, by which the 
 water can be injected into the cylinder beneath its piston ; 
 the pump has of course valves to prevent the return of the 
 water. Now, suppose the diameter of the cylinder to be six 
 inches, and the diameter of the piston of the small pump, or 
 injector, only one-quarter of an inch ; the proportions between 
 the two surfaces or ends of the said pistons will be as the 
 squares of their diameters, which are as 1 to 24 ; therefore the 
 areas will be as 1 to 6/6 ; and supposing the intermediate 
 space between them to be filled with water, or any other 
 dense and incompressible fluid, any force applied to the small 
 piston will operate on the other in the above proportion of 
 1 to 576 . Suppose the small piston, or injector, to be forced 
 down, when in the act of forcing or injecting, with a weight 
 of 20 cwt., which can easily be done by means of a long 
 lever, the piston of the great cylinder would then be moved 
 up with a force equal to 1 ton multiplied by 576. 
 
 Fig. 343 represents a crane constructed upon the hydro- 
 statical principle, that is, by the injection of water from a 
 small pump into a large cylinder, which is fitted with a piston, 
 having a rack attached to it for the purpose of turning a pinion 
 upon the axis of a large drum- wheel or barrel, round which 
 the rope is coiled, and from thence passes to the jib. 
 
 Tlie figure A A represents the jib, made of iron, and supported upon two 
 brackets a a, projecting from the wall of the warehouse in which the crane is 
 supposed to be erected. The rope passes over the pulley S, and down through 
 holes in the brackets a a, then turns under the pulley b, and comes to the lower 
 side of the great drum-wheel B. Tire pinion C is fixed on the same axis with 
 this, and its gudgeons turn in small iron frames d, bolted down to the floor of 
 the warehouse. The pinion C is actuated by the teeth of the rack D, and a 
 small roller, whose pivot is shown at e, presses against the back of the rack, 
 to keep its teeth up to the pinion. The rack is attached to the piston D 
 of the cylinder L, in which the power for working the crane is obtained. 
 The piston passes through a tight collar of leather on the top of the cylinder 
 at E, which does not admit of any leakage by the side of it, and therefore if 
 any water is forced into the cylinder it must protrude the piston from it. 
 The cylinder is supported in a wooden frame F F, and has a small copper 
 
 U 
 
290 
 
 THE OPERATIVE MECHANIC 
 
 pipe g proceeding from the lower end of it, communicating with a small 
 forcing-pump at h ; this stands in an iron cistern H, which contains tlie 
 water, and sustains the standard i i, for the centre of the handle G, with 
 which the pump is worked by one or two men. The upper extremity of the 
 standard i i guides the piston-rod of the pump, to confine it to a vertical 
 motion ; Z is a weight for counterbalancing the handle G of the pump. 
 From what we have said before, the operation of this machine is evident; 
 the power of the cylinder D is in proportion to its size compared with the 
 size of the pump ; but as it only acts through short limits, the pinion and 
 drum B are necessary to raise the weight a sufficient height. The operation 
 of lowering goods by this crane is extremely simple, as it is only necessary 
 to open a cock at wi, which suffers the water to escape from the cylinder into 
 the cistern H, and the weight descends, but under the most perfect command 
 of the person who regulates the opening of the cock ; for by diminishing 
 the aperture, he can increase the resistance at pleasure, or stop it altogether. 
 Fig. 345 is a side elevation of a crane. The post is immovable, and is 
 fixed on an iron frame, with arms extending in the form of a cross, the 
 extremities of which are bolted down by strong screws to large blocks of 
 stone sufficiently heavy to more than counterpoise the weight to be raised 
 by the crane. In the top of the post is fixed a wrought-iron pivot, by which 
 the weight is supported, and a strong cast-iron cap bears on the pivot, and 
 has attached to it two iron frames, one on each side, that receive the pres- 
 sure from the stay, as well as support the pull of the jib, which is formed of 
 two bars of wrought-iron ; the lateral pressure is borne by the bottom of the 
 post, round which two friction-rollers turn to facilitate its motion. This 
 crane will carry five tons with safety. 
 
4.ND MACHINIST. 
 
 291 
 
 PRESSES. 
 
 The press is a machine in most extensive use in the 
 mechanic arts. It is usually made of wood, or iron, and 
 serves to squeeze or compress any body very close. 
 
 Screw-presses generally consist of six members, or pieces ; 
 viz. two flat smooth tables of wood or metal, between which 
 the substance to be pressed is placed ; two screws, or worms, 
 fastened to the lower plank, and passing through two holes 
 in the upper ; and two nuts, in form of an S, serving to drive 
 the upper plank, which is movable, against the lower which 
 is stable and without motion. 
 
 Presses used for expressing liquors, are of various kinds ; 
 some, in most respects, the same as the common presses, 
 excepting that the under plank is perforated with a great 
 number of holes, to let the juice run through into a tub or 
 receiver underneath. 
 
 1. An improved cider-press, turned by a windlass, is shown 
 in fig. 284. 
 
 A A is the base or foundation with its supporting parts ; B B the cheeks or 
 sisters ; D D the cross-piece at top, through which the screw passes, and 
 which consequently contains the female screw ; E the screw with its 
 appendages ; F F the bridge or cross-piece which acts on the pommage j 
 G G is the wide plank or vat on which the pulp rests in the hair bags, in 
 which the mode of the liquor’s passing off is seen. 
 
 This kind of press may be advantageously employed for packing cloth, 
 paper, and other goods ; as also in paper-mills, for flattening and rendering 
 paper solid ; and in the manufacture of woollen cloth, for glazing and setting 
 a linish upon the article in its last stage. 
 
 2. Two elevations of a very good screw-press for a paper- 
 mill are given in figs. 285 and 286. 
 
 A A is the bed, formed of an immense beam of oak ; and each of the 
 cheeks, B, consists of a long iron bar b b, fig. 286, the ends of which are 
 welded together, so that it forms a long sink, one end of which receives the 
 end of the bed A, and the other the end of a massive cast-iron bar D, 
 through which the screw E is received, and its nut fixed fast therein. 
 The open spaces of the long links or cheeks, 6, h, are filled up by rails of 
 wood C, which support the weight of parts of the press when it is not in 
 action, but these bear nothing when the press has any articles under 
 pressure in it ; these articles are laid at H, on the bed, and the follower, G, 
 is pressed upon them by the screw, when it is turned by a long lever put 
 through the holes in the screw-head F. 
 
 The screws employed for paper-presses are generally formed with such 
 coarse threads, and so rapid a spiral, that the elasticity of the paper is suffi- 
 cient to force it to run back. To these a ratchet-wheel, a, is fixed, and a 
 click e, fig. 287, is applied to its teeth ; to prevent its return, the click is 
 supported on a bar b rf, which moves on a centre at B, but the other end is 
 retained by a catch or lever /^. When the press is to be relieved, the 
 
 u 2 
 
292 
 
 THE OPERATIVE MECHANIC 
 
 end /, of the catch, is driven back ; this relieves the bar d b, and the click 
 no longer detaining the ratchet-wheel, the screw runs back. 
 
 'S. A very ingenious and useful 2 )acking-press has been 
 invented by Mr. John Peek. It is represented in fig. 288. 
 
 A A, the frame of the press ; B B, the large screws, which, in this press, 
 contrary to those in common use, is fix«d and immovable ; C, a circular 
 iron bar, extending beyond the sides of the press, and having thereon two 
 worms, or endless screws E E, which work in two toothed wheels fixed 
 to the nuts, and, by turning the winch D, drive the nuts and bed up and 
 down the screws as may be found necessary ; F, a stage, suspended from 
 the bed, and on which the men stand who work the press ; such a stage 
 may, if found necessary, be fixed at the other end of the bar, as shown by 
 the square shoulder G. The bed of this press must be formed of two 
 pieces of strong wood, which are held together by screws and nuts, passed 
 through them^ as shown at 4 A A k. The great utility of this press consists in 
 its' being capable of packing two sets of bales at once ; thus answering the 
 purpose of two presses, with more expedition. 
 
 4. The hydrostatic or water-press, or as it is sometimes 
 called Bramah's Press, has, for a great number of purposes, 
 superseded the use of the screw-press, over which it possesses 
 great advantages, in all cases where a strong pressure is 
 required. It is one among the many useful inventions of the 
 late Mr. Joseph Bramah, of Piccadilly; and is ingeniously 
 contrived for applying the quaqua versum pressure of fluids 
 as a powerful agent in many kinds of machinery. 
 
 These contrivances consist in the application of water, or 
 other dense fluids, to various engines, so as, in some instances, 
 to cause them to act with immense force ; in others, to com- 
 municate the motion and powers of one part of a machine to 
 some other part of the same machine ; and, lastly, to com- 
 municate the motion and force of one machine to another, 
 where their local situations preclude the application of all 
 other methods of connection. 
 
 Tbe first and most material part of this invention will be clearly under- 
 stood by an inspection of fig. 289, where A is a cylinder of iron, or other 
 materials, sufficiently strong, and bored perfectly smooth and cylindrical ; 
 into which is fitted the piston B, which must be made perfectly water-tight, 
 by leather or other materials, as used in pump-making. The bottom of the 
 cylinder must also be made sufficiently strong with the other part of the 
 surface, to be capable of resisting the greatest force or strain that may at 
 any time be required. In the bottom of the cylinder is inserted the end of 
 the tube C ; the aperture of which communicates with the inside of the 
 cylinder, under the piston B, where it is shut with the small valve D, the 
 same as the suction-pipe of a common pump. The other end of the tube 
 C communicates with the smaH forcing-pump or injector E, by means of 
 which water or other dense fluids can be forced or injected into the cylinder 
 A, under the piston B. Now, suppose the diameter of the cylinder A be 
 1 2 inches, and the diameter of the piston of the small pump or injector E 
 only one quarter of an inch, the proportion between the two surfaces or ends 
 of the said piston will be as 1 to 2304 ; and supposing the intermediate 
 
Jfe^ tc SiscM^, SCJS‘ Strimd. . 
 
AND MACHINIST. 
 
 293 
 
 space between them to be filled with water or other dense fluid capable of 
 sufficient resistance, the force of one piston will act on the other just in the 
 above proportion, viz. as 1 is to 2304. Suppose the small piston in the 
 injector to be forced down when in the act of pumping or injecting water 
 into the cylinder A, with the power of 20 cwt. which could easily be done 
 by the lever H ; the piston B would then be tnoved up with a force equal 
 to 20 cwt. multiplied by 2304. 
 
 Thus is constructed a hydro-mechanical engine, whereby a weight 
 amounting to 2304 tons can be raised by a simple lever, through equal 
 space, in much less time than could be done by any apparatus con- 
 structed on the known principles of mechanics; and it may be proper 
 to observe, that the effect of all other mechanical combinations is coun- 
 teracted by an accumulated complication of parts, which renders them 
 incapabl-e >of being usefully extended beyond a certain degree ; but in 
 machines acted upon or constructed on this principle every difficulty of 
 this kind is obviated, and their power subject to no finite restraint. To 
 prove this, it will be only necessary to remark, that the force of any machine 
 acting upon this principle can be increased ad infinitum, either by extending 
 the proportion between the diameter of the cylinder A, or by applying 
 greater power to the lever H. 
 
 Fig. 290 represents the section of an engine, by which very wonderful 
 effects may be produced instantaneously by means of compressed air. 
 A A is a cylinder with the piston B fitting air-tight, in the same manner as 
 described in fig. 289. C is a globular vessel made of copper, iron, or other 
 strong materials, capable of resisting immense force, similar to those of 
 air-guns ; D is a strong tube of small bore, in which is the stop-cock E. 
 One of the ends of this tube communicates with the cylinder under the 
 piston B, and the other with the globe C. Now, suppose the cylinder A 
 to be the same diameter as that in fig. 289, and the tube D equal to one 
 quarter of an inch diameter, which is the same as the injector, fig. 289; 
 then, suppose that air is injected into the globe C (by the common method) 
 till it presses against the cock E with a force equal to 20 cwt. which can 
 easily be done ; the consequence will be, that when the cock E is opened, 
 the piston B will be moved in the cylinder A A with a power or force equal 
 •to 2304 tons ; and it is obvious, as in the case fig. 289, that any other unlimited 
 degree of force may be acquired by machines or engines thus constructed. 
 
 Fig. 291 is a section, merely to show how the power and motion of one ma- 
 chine may, by means of fluids, be transferred or communicated to another, 
 let their distance and local situation be what they may. A and B are two 
 small tubes, smooth and cylindrical, in the inside of each of which is a 
 piston, made water and air tight, as in figs. 288 and 289. C C is a tube 
 conveyed under ground, or otherwise, from the bottom of one cylinder to the 
 other, to form a communication between them, notwithstanding their dis- 
 tance be never so great, this tube being filled with water or other fluid, 
 until it touch the bottom of the piston ; then, by depressing the piston A, 
 the piston B will be raised. The same effect will be produced vice versa : 
 thus bells may be rung, v/heels turned, or other machinery put invisibly 
 jn motion, by a power being applied to either. 
 
 Fig. 292 is a section, showing another instance of communicating the 
 action and force of one machine to another ; and how water may be raised 
 cut of wells of any depth, and at any distance from the place where the 
 operating power is applied. A is a cylinder of any required dimensions, 
 in which is the working piston B, as in the foregoing examples ; into the 
 bottom of this cylinder is inserted the tube C, which may be of less bore 
 4h?.n the cylinder A, This tube is continued, in any required direction^ 
 
204 
 
 THE OPERATIVE MECHANIC 
 
 down to the pump cylinder D, supposed to be fixed in the deep well E B, 
 and forms a junction therewith above the piston E ; which piston has a rod 
 G, working through the stuffing-box, as is usual in the common pump. To 
 this rod G is connected, over a pulley or otherwise, a weight II, sufficient 
 to overbalance the weight of water in the tube C, and to raise the piston F, 
 iwhen the piston B is lifted ; thus, suppose the piston B is drawn up by its 
 rod, there will be a vacuum made in the pump cylinder D, below the piston 
 F ; the vacuum will be filled with water through the suction pipe, by the 
 pressure of the atmosphere, as in all pumps fixed in air. The return of the 
 piston B, by being pressed downwards in the cylinder A, will make a 
 stroke of the piston in the pump cylinder D, which may be repeated in the 
 usual way by the motion of the piston B, and the action of the water in the 
 tube C. The rod G of the piston F, and the weight H, are not necessary 
 in wells of a depth where the atmosphere will overbalance the water in the 
 suction of the pump cylinder D, and that in the tube C. The small tube 
 and cock in the cistern I, are for the purpose of charging the tube C. 
 
 By these means it is obvious that the most commodious 
 machines, of prodigious power, and susceptible of the greatest 
 strength, may readily be formed. If the same multiplication of 
 power be attempted by toothed wheels, pinions, and racks, it 
 is scarcely possible to give strength enough to the teeth of 
 the racks, and the machine becomes very cumbersome and of 
 great expense. But Mr. Bramah’s machine may be made to 
 possess great strength in very small compass. It only requires 
 very accurate execution. Mr. Bramah, however, was greatly 
 mistaken when he published it as the discovery of a new 
 mechanic power. The principle on which it depends has 
 been well known for nearly two centuries ; and it is matter 
 of surprise that it has never before been applied to any useful 
 practical purpose. 
 
 5. The Stanhope printing-press is delineated in figs. 293 
 and 294, being elevations, and fig. 295, a plan. 
 
 A A is a massive frame of cast-iron formed in one piece ; this is the 
 body of the press, in the upper part of which a nut is fixed for the reception 
 of the screw 6, and its point operates upon the upper end of a slider rf, 
 which is fitted into a dove-tail groove formed between two vertical bars e c, 
 ,of the frame. The slider has the platen D D firmly attached to the lower 
 end of it ; and being accurately fitted between the guides e e, the platen 
 must rise and fall parallel to itself when the screw b is turned. The weight 
 of the platen and the slider are counterbalanced by a heavy weight E, behind 
 the press, which is suspended from the lever F, and this acts upon the slider 
 to lift it up, and keep it always bearing against the point of the screw. 
 
 At G are two projecting pieces, cast all in one with the main frame, to 
 support the carriage when the pull is made ; to these the rails H are 
 screwed, and placed truly horizontal, for the carriage I to run upon them, 
 when it is carried under the press to receive the impression, or drawn out 
 to remove the printed sheet. The carriage is moved by the rounce or 
 handle K, with a spit and leather girts very similar to the wooden press. 
 Upon the spit or axle, a wheel, L, is fixed, and round this leather belts are 
 passed, one extending to the back of the carriage to draw it in, and two 
 others, which pass round the wheel in an opposite direction, to draw it cut. 
 
AND MACHINIST. 
 
 295 
 
 By this means, when the handle is turned one way it draws out the car- 
 riage, and by reversing the motion it is carried in. There is likewise a 
 check strap /, from the wheel down to the wooden base M, of the frames, 
 and this limits the motion of the wheel, and consequently the excursion of 
 the carriage. 
 
 The principal improvement of Earl Stanhope’s press con- 
 sists in the manner of giving motion to the screw, b, of it, 
 which is not done simply by a bar or lever attached to the 
 screw, but by a second lever e, g; the screw, b, has a short 
 lever, g, fixed upon the upper end of it^ and this communi- 
 cates by an iron bar, or link. A, to another lever, of rather 
 shorter radius, which is fixed upon the upper end of the 
 second spindle I, and to this the bar or handle, A, is fixed. 
 Now when the workman pulls this handle, he turns round 
 the spindle Z, and by the connection of the rod, A, the screw, A, 
 turns with it, and causes the platen to descend and produce 
 the pressure. But it is not simply this alone, for the power 
 of the lever. A, is transmitted to the screw, in a ratio propor- 
 tioned to the effect required at the different parts of the pull ; 
 thus at first, when the pressman takes the bar K, it lies in a 
 direction parallel to the frame, or across the press, and the 
 short lever i (being nearly iierpendicular thereto) is also 
 nearly at right angles to the connecting rod A ; but the lever, 
 g, of the screw, makes a considerable angle with the rod, 
 which therefore acts upon a shorter radius to turn the screw ; 
 because the real power exerted by any action upon a lever, 
 is not to be considered as acting with the full length of the 
 lever between its centres, but with the distance in a perpen- 
 dicular drawn line, in which the action is applied to the 
 centre of the lever. Therefore when the pressman first takes 
 the handle K, the lever i acts with its full length upon a 
 shorter length of leverage, g^ on the screw, which will con- 
 sequently be turned more rapidly than if the bar itself was 
 attached to it ; but on continuing the pull, the situation of 
 the levers change, that of the screw, g, continually increasing 
 its acting length, because it comes nearer to a perpendicular 
 with the connecting rod, and at the same time the lever 
 diminishing its acting length, because, by the obliquity of 
 the lever, the rod. A, approaches the centre, and the perpen- 
 dicular distance diminishes ; the bar or handle also comes to 
 a more favourable position for the man to pull, because he 
 draws nearly at right angles to its lengths 
 
 All these causes combined have the best effect in producing 
 an immense pressure, without loss of time ; because in the 
 first instance the lever acts with an increased motion upon 
 the screw, and brings the platen down very quickly upon the 
 
296 
 
 THE OPERATIVE MECHANIC 
 
 paper, but by that time the levers have assumed such a 
 position as to exert a more powerful action upon each 
 other, and this action continues to increase as the bar is 
 drawn forwards, until the lever, ^, and the connecting rod are 
 brought nearly into a straight line, and then the power is 
 immensely great, and capable of producing any requisite 
 pressure which the parts of the press will sustain without 
 yielding. The handle is sometimes made to come to rest 
 against a stop, which prevents it moving further, and there- 
 fore regulates the degree of pressure given upon the work : 
 but to give the means of increasing or diminishing this 
 pressure, for different kinds of work, the stop is made mov- 
 able to a small extent. A better plan is adopted by some 
 makers of the Stanhope press, viz. to have a screw adjust- 
 ment at the end of the connecting rod A, by which it can be 
 shortened ; it is done by fitting the centre pin which unites 
 it to the lever g, in a bearing piece, which slides in a groove 
 formed in the rod, and is regulated by the screw. This 
 shortening of the connecting rod produces a greater or less 
 descent of the platen, when the handle is brought to the stop. 
 
 The carriage of the press is represented with wheels, m m, beneath, to take 
 .off the friction of moving upon the ribs H. These wheels are shown at 
 fig. 296, which is a section of the screw and the platen, with the carriage 
 beneath it ; and fig. 297 is a plan answering to it. Fig. 298 is a figure of 
 a carriage inverted to show the wheels ; then axles n are fitted to springs jo, 
 and these are adjustable by means of screws r, so that the carriage will be 
 borne up to any required height. This is so regulated, that when the car- 
 riage is run into the press, its lower surface shall bear lightly upon the solid 
 cheeks G, which are part of the body of the press, and these support it when 
 the pressure is applied, the same as the winter of the old press ; but the 
 wheels by their springs act to bear up great part of the carriage with the 
 types upon it, and diminish the friction, yet do not destroy the contact of 
 the carriage upon the ribs, because this would not give the carriage that 
 solidity of bearing which is requisite for resisting the pull. This is only at 
 the time when the carriage is run into the press ; because as it runs out, the 
 ribs on which the wheels run rise higher, and therefore the wheels support 
 the whole weight. 
 
 The manner in which the wheels run in rebates or recesses in the edges 
 of the ribs, is shown at fig. 294. Tlie carriage is made of cast-iron, in the 
 form of a box, with several cross partitions, which are all cast in one piece, 
 and thougk njade of thin metal, are exceedingly strong ; the upper surface 
 is made truly flat, by turning it in a lathe. The same of the platen, which 
 is likewise a shallow box ; the slider d has a plate formed on the lower end 
 of it, which is fixed by four screws upon the top of the platen, and thug 
 they are united. 
 
 At the four angles of the carriage, pieces of iron, r, fig. 297, are screwed 
 on, to form bearings for the quoins or wedges which are driven in to fasten 
 the form of types upon it in the true position for printing. The tympan P, 
 fig. 293, is attached to the carriage by hinges, with an iron bracket or stop 
 jto catch it when it is thrown back ; the frisket, R, is joined to the tympan. 
 
STAI^MOFIE JPFIIYTII^(C^ JPmiESS,&e. 
 
 I'rorn 293 to 299. :ei-3e. * 
 
 299 
 
 yetle ie Stcck2c^ Str-:tnd,. 
 
 ■Mss 
 
AND MACHINIST. 
 
 297 
 
 and when opened out, rests against a frame suspended from the ceiling. 
 The iron frame, A, of the press is screwed down upon the wooden base M, 
 by bolts, which pass through feet, s, projecting from the lower parts of the iron 
 frame. Another wooden beam is fixed into the former at right angles, so as 
 to form a cross, which lies upon the floor. The ribs H, for the carriage to 
 run upon, are supported from the wooden base by an iron bracket T. 
 
 The advantages of the iron presses in working are very 
 considerable, both in saving labour and time. The first arises 
 from the beautiful contrivance of the levers, the power of the 
 press being almost incalculable at the moment of producing 
 the impression ; and this is not attended with a correspondent 
 loss of time, as is the case in all other mechanical powers, 
 because the power is only exerted at the moment of pres- 
 sure, being before adapted to bring down the platen as 
 quickly as possible. This great power of the press admits of 
 a saving of time, by printing the whole sheet of paper at one 
 pull, the platen being made sufficiently large for that pur- 
 pose ; whereas, in the press formerly used, the platen is only 
 half of the size of the sheet. In the Stanhope press, the 
 whole surface is printed at once, with far less power upon 
 the handle than the old press, when printing but half the 
 surface. This arises not only from the levers, but from the 
 iron framing of the press, which will not admit of any yield- 
 ing, as the wood always yields, and indeed is intended to do, 
 the head being often packed up with elastic substances, such 
 as pasteboard, or even cork. In this case much power is lost, 
 for in an elastic press the pressure is gained by screwing or 
 straining the parts up to a certain degree of tension, and the 
 effort to return, produces the pressure. Now, in this case, 
 the handle will make a considerable effort to return, which, 
 though it is in reality giving back to the workman a portion 
 of the power he exerted on the press, is only an additional 
 labour, as it obliges him to bear the strain a longer time than 
 he otherwise would. 
 
 The iron presses have very little elasticity, and those wl»o 
 use them find it advantageous to diminish the thickness of the 
 blankets in the tympan to one very thin piece of fine cloth ; the 
 lever has then very little tendency to return, and the pull is 
 easy in the extreme, requiring very little more force to remove 
 it at the latter than at the first part; indeed, the iron press is so 
 different from the other press, that when an experienced press- 
 man first tries it, he cannot feel any of that reaction which he 
 has been accustomed to, and will not believe, till he sees the 
 sheet, that he has produced any impression at all ; and for many 
 days after he begins to work at an iron press, he by habit 
 throws back all the weight of his body in such a maimer as to 
 
298 
 
 THE OFERATIVK MECHANIC 
 
 bring the handle up to its stop with a concussion that shakes 
 his arm very much, and in consequence most pressmen, after 
 a few hours^ work, feel inclined to give up the iron press ; 
 but when they have once acquired a new habit of standing more 
 upright, and applying only as much force as it requires, the 
 labour of the pull becomes less than that of running the car- 
 riage in and out ; and men who are accustomed to the iron 
 presses only, would be scarcely able to go through the work 
 of the old press. 
 
 Mr. De la Haine has a patent for a Stanhope press, which 
 answers extremely well ; the only material alteration is, that 
 he has substituted a spiral or curved inclined plane in place 
 of the screw, which is fixed to the head of the press ; and 
 a cross-arm properly formed, and fixed on the upper end of 
 the spindle, which, standing in place of the screw, acts against 
 the fixed inclined plane. The action is very nearly the same 
 as the screw, except that the surfaces admit of being made 
 of hardened steel, and thus diminish the friction very much. 
 The inventor of this for the common press was Mr. Roworth ; 
 but Mr. De la Haine has combined it with the levers and iron 
 frame of the Stanhope press. 
 
 A common press, of great simplicity, and possessing the 
 same advantage in point of power as Lord Stanhope gains by 
 the compound levers, has been produced by Mr. Medhurst, 
 of Denmark-street, Soho. 
 
 6. In November 1813, Mr. John Ruthven, of Edinburgh, 
 took out a patent for an improvement in the printing-press, 
 which differs from those heretofore used in the following 
 particulars : 
 
 First, The types, plates, blocks, or other surfaces from 
 which the impression is to be taken, instead of being situated 
 upon a running carriage, as was formerly the practice, are 
 placed upon a stationary platform or tablet, which is provided 
 with the usual apparatus known to printers by the names of 
 tympan and frisket, with points, &c. to receive the sheet 
 of paper and convey it to its proper situation on the types 
 after they had been inked. 
 
 Secondly, The machinery by which the power for the 
 pressure is produced, is situated immediately beneath this 
 platform or tablet ; and the platen or surface which is op- 
 posed to the face of the types, to press the sheet of paper 
 against them, can be brought over the types, and connected 
 at two opposite sides or ends with the machinery beneath the 
 tablet ; by this machinery it is so forcibly pressed or drawn 
 down upon the paper, which lays upon the types, as to give 
 
AND MACHINIST. 
 
 299 
 
 the impression ; which being thus made, the platen can lie 
 disunited from the machinery, and removed from oif the types 
 by the foot^ or otherwise, to take out the paper, and introduce 
 a fresh sheet. 
 
 Thirdly, The said machinery for producing the pressure is 
 a combination of levers, actuated by a crank, or short lever, 
 turned by a winch, or handle, to which the pressman applies 
 by his hand ; or the pressure may be produced by the tread 
 of the foot. 
 
 Fig. 299 is a horizontal plane ; fig. 300, a vertical section 
 taken through the middle ; and fig. 301, an end view 3 the 
 same letters of reference being used in each. 
 
 A A represent the tablet or surface upon which the types, &c. are laid, its 
 surface truly flat, and may be made of wood, stone, or metal, or any other 
 substance used for the carriage of printing-presses. This tablet is mounted 
 upon a frame of wood or metal, consisting of legs B B, and cross braces 
 C C, or any other kind of support may be used which will firmly sustain 
 the tablet at a proper height from the ground. The tablet has a tympan, 
 8 and 0, joined to it at the end, 9, in the usual manner, and open into the 
 position of the dotted lines 1 0, to take off or put on the sheet of paper, 
 which is confined by the frisket, 11, in the usual manner ; the dotted lines, 
 12, represent the gallows or support for the tympan and frisket when 
 opened. 
 
 For fastening the types upon the tablet, or what the printers call making 
 register, quoins or w^edges may be introduced at the angles, in the usual 
 manner; but a preferable method is to have screws 13, 13, fitted through 
 pieces which are made fast to the sides of the tablet, and between the points 
 of these screws the chase, or frame of types, is held steady upon the tablet, 
 and may be adjusted. 
 
 Beneath the tablet are the levers marked D E, D E, their fulcrums, or 
 fixed centre-pins, being at D, and they act upon double hooks or clutches, 
 F F. When the ends E are depressed by means of the third lever I G, 
 situated beneath and common to both, the connection being made with the 
 link a, the fulcrum of the lever is at G ; and H is a third point to which 
 the power to actuate it is applied by a connecting rod K, the opposite end 
 of which is joined to a crank or short lever L M, situated upon an axis or 
 spindle L, which extends to the front of the machine, and has a winch or 
 handle N, fig. 299, upon it, for the pressman to turn it by. 
 
 The platen of the press is shown at O O ; it may be made of wood or 
 iron, as usual, but must be exactly true on the low'er surface, which applies 
 to the face of the types b b, upon the tablet A A. On the top of the platen 
 is a strong metal bar P, which may be either cast in one piece with it, or 
 united to it by screws at r r ,• at its extremities it has bolts d d, fixed to it 
 by screws or otherwise ; and at their lower ends they must have heads 
 which are exactly fitted to the clutches or double hooks F F, before de- 
 scribed. By means of these the platen is connected with the lever D E, D E, 
 so that a pressure may be produced when the handle N is turned in the 
 direction shown by the arrow in fig. 300. This, by turning the lever M 
 about upon its centre L, pushes the rod K, which acting upon the point H 
 of the lever G H I, moves it upon its centre G, and depresses the point I, 
 which being connected with the extremities E of the levers D E, by the 
 link fl, they are made to partake of its motion, and draw down the platen 
 
300 
 
 THE OPEilATIVE MECHANIC 
 
 upon the types by the clutches F F, and hooks dd. By returning the winch 
 N to its original position, the pressure is relieved, and the platen may be 
 removed from the types thus ; — At the end of the bar P, two springs, e e, 
 figs. 299 and 301, are fixed; and in the ends of these rollers or wheels, 
 marked/, are fitted to revolve freely upon their centre-pins. These wheels, 
 having grooves in their edges, run upon sharp angles, formed upon the 
 upper edge of the two rails R R, which are extended across the frame of the 
 press,and project sufficiently behind, as in figs. 299 and 301, being supported 
 by brackets g, of fig. 301, if necessary. Upon these bars and wheels (or 
 sliders may be used instead of wheels) the platen will run freely, to remove 
 it backwards and forwards off the types, but when brought over them the 
 bolts d d will enter the clutches F F, ready to receive the action of the levers, 
 and give the pressure upon the tympan. 
 
 The springs e are so adjusted, that when the platen runs backwards or 
 forwards upon the rails R, the under surface of it will be sufficiently raised 
 above the tympan to run clear of it; but when the hooks dd and F P’ are 
 united, and the pressure given by turning the handle N, these springs yield, 
 though they have sufficient strength to raise up the platen clear of the 
 tympan, the instant the pressure is relieved. 
 
 To draw the platen forward over the types, a handle h is fixed upon it, 
 for the pressman to take hold by ; but it may be brought by the foot, in the 
 following manner : the two foremost wheels, f f, have links, k k, jointed 
 to their centre-pins, to connect them with the upper ends of the two long 
 levers m m, which are fixed to one common axis n, fig. 300, extending across 
 the whole machine, near the ground ; upon the axis a short lever o, fig. 301, 
 is fixed, and a rod q unites it to the end of the bent lever r the arm i of 
 which is made broad, to serve as a paddle for the foot; by depressing this, 
 the arm r draws the short lever o, and the long lever m m causes the platen 
 to advance truly parallel, and come up to the clutches F F. 
 
 To make all the work compact, the centres D D of the great levers, and 
 of the lower lever G, as well as the pivots L of the winch N, are all sup- 
 ported in one frame composed of two metal cheeks S S, which are situated 
 beneath the table, and united thereto by screws, or otherwise, as shown by 
 the dotted line in the plan, fig. 299. 
 
 The power of the press will depend upon the proportion of the different 
 levers, and the relation between the space described by the motion of the 
 handle N, and the descent of the platen O ; but it should be observed, that 
 the power of this press increases as the handle descends to the horizontal 
 position shown in fig. 300 ; first, because the handle is then in the most 
 favourable position to receive the workman’s body ; secondly, the lever L M 
 comes to a position which gives it a great power to force the rod K, viz. as 
 is shown by the dotted line L 2, for when the lever and rod come to one 
 straight line, its power to force the rod K may be considered as infinitely 
 great ; thirdly, the lever G H is in the most favourable position, marked G 2, to 
 receive the action of the rod K, viz. perpendicular to it; fourthly, the lever 
 G I is in a position to have greater power on the links a and the levers D E, 
 than when it is in a horizontal position. All these sources combined have 
 the best effect in saving time, and at the same time producing immense 
 pressure ; for when the pressure first takes hold of the handle N, it acts but 
 with little advantage with respect to power on the levers, and therefore 
 brings the platen down very quickly upon the tympans, with little loss of 
 time or motion, till they have assumed positions in which they exert more 
 powerful action upon each other, as above stated ; and this action continues 
 to increase until the lever L M and rod K come nearly into a line, when the 
 power is immensely great, and cax>able of producing any required pressure, 
 
JRUT.KiyOT^S TJKJlTlTOir JPiEI':SS 
 
 /r'/vm ,mto3t>2y 
 
 J^L3 7. 
 
 Jl^v92ff Sc Str^and- 
 
AND MACHINIST. 
 
 301 
 
 t^hich the parts of the press will withstand without yielding. The handle N is 
 made to come to a stop, or rest, which prevents its moving farther than the 
 position of the dotted lines, and therefore regulates the degree of pressure 
 given upon the work. But to give the means of increasing or diminishing 
 the pressure at pleasure for different kinds of work, the centre hole of the 
 pin H is made in a piece, which is fitted in a groove in the rod K; therefore 
 by sliding it in the groove, it has the same effect as lengthening the rod, 
 which produces a greater descent of the platen when the handle is brought to 
 a stop ; a screw, s, is fitted into the end of the groove, to screw the packing 
 tight in the groove, and prevent it getting loose in working. 
 
 Another method of producing the same effect is to adjust the nuts which 
 are fitted on the screws at the top of the bolts dd ; or it may be done by 
 loosening the screws at r, and fitting packing between the fitting of the 
 platen and the bar P ; the same may be done to adjust the platen parallel, if 
 it prints more at one part than another. 
 
 Springs may be applied to take off all shake or loosenesses in the joints ; 
 it may be done in different ways : a strong spring may be fixed beneath the 
 tablet, and act upon the clutch F, to lift it up, and keep the joint tight ; or 
 one small spring may be fixed on the lever D E, (as shown on the opposite 
 side,) to lift the clutch F, and another being fixed to the lever beneath, and 
 resting at the end upon a pin in the frame, will lift up the lever and link c, 
 to keep them all tight for working. If it be thought objectionable for the 
 rod K to push endways on the levers, it may be contrived to draw or pull, 
 by placing the lever M above the spindle L, instead of beneath it, and also 
 reversing the form of the lever G H I ; the points G and H to remain as they 
 are, but the point I to be on the opposite side of the centre, viz. above it ; 
 and with this alteration the drawing of the rod K will produce the pressure, 
 instead of pushing it, as in the figure. 
 
 Fig. 302 shows another arrangement of the lever for a press. In this 
 figure the same letters are used to denote the same parts, thus : A is the 
 tablet, D E the levers, F the clutches, O the platen, P the cross-bar ; the 
 ends E of the levers are connected by a link a, with a third lever T W, w'hose 
 centre or fulcrum is at V ; the powder is applied to the long end by a chain t, 
 which is conducted over a pulley or roller v, and wound upon a wheel w, 
 which is fixed upon the axle of the handle to work the press. To give 
 greater power, the wheel may be formed like a spiral, instead of circular, 
 that the chain may lay upon a shorter radius when the pressure is produced. 
 
 7. Within these few years, numerous and great improve- 
 ments have been made in printing-presses ; but the best that 
 we have seen is the invention of Messrs. Bacon and Donkin, 
 who exhibited it before the university of Cambridge, by whom 
 it is now employed in the printing of bibles and prayer-books, 
 
 Jlessrs. Bacon and Donkin^s press consists in adapting 
 the types to be fitted upon, and form the surface of a prismatic 
 roller, such as a square, pentagon, hexagon, octagon, or other 
 figure, and mounting this in a frame, with the means of turn- 
 ing it round upon its centres ; a second roller is applied in 
 such a manner, that its surface will keep in contact with the 
 surface of the types, which are inked, and the machine being 
 put in motion, the paper which is to be printed is passed 
 through and receives the impression. The types are inked 
 
302 
 
 TKie OPERATIVE MECHANIC 
 
 by a cylinder which is applied to revolve with its surface in 
 contact with them. By this invention, the advantages of 
 types between rollers are obtained, although the types are 
 imposed upon plain surfaces. 
 
 Fig. 303 contains a perspective view of a machine, the prism A of which is 
 square in its section, and has the ordinary types or letter-press applied upon 
 its four sides, and firmly attached to it. The pivots at the end of the axis of 
 this prism are supported in the frame B B, and it is caused to revolve by a 
 connection of wheel- work D E and F G, from the winch and fly-wheel at H, 
 The types upon its surface are caused to print upon the paper by means of 
 a second roller I i, called the platen, placed immediately beneath the 
 former, and its surface being formed to a particular curvature, produced by 
 four segments of cylinders, its circumference, when it turns round, will always 
 apply to the surface of the types, and thus a sheet of paper being introduced 
 between them, will receive the impression. The ink is applied to the types 
 by means of a cylinder K K, placed above the prism ; it is composed of a 
 soft elastic substance ; and that its surface may always apply to the types, 
 its spindle is fitted in pieces L L, which moving upon an axis n, permit the 
 cylinder to rise and fall, to accommodate itself to the motion of the types. 
 The ink-cylinder receives its ink from a second cylinder M M, which is 
 called the distributing-roller, also composed of a soft substance, and is sup- 
 plied with ink by a third ink-roller N N, which is made of metal, and 
 extremely true. The ink is lodged in quantity against this roller upon a 
 steel plate O O, the edge of which being placed at a very small distance 
 from the circumference, permits the roller, as it revolves, to carry down 
 a very thin film of ink upon its surface, and this being taken ofl’ by the 
 distributing-roller, is applied to the surface of the inking-cylinder, which, as 
 before mentioned, inks the types. 
 
 The sheet of paper is introduced, as shown in the figure, by placing it 
 upon a blanket, which is extended upon a feeding-board P P, and drawn 
 into the machine at a proper time, by having a small ruler, 2, fixed to it. 
 The ends of this are taken forward by two studs b, attached to endless chains, 
 which are extended from the wheels <?, e, at the end of the platen, to other 
 wheels d, rf, which are supported in the frame of the feeding-board. The 
 wheels e, e, having teeth entering the links of the chains, cause them to 
 traverse when the machine is turned round, and at the proper time the pins, 
 6, draw the ruler, 2, and blanket forward, and introduce the paper into 
 the machine, and by passing between the prism and platen it is printed, as 
 before mentioned. This is the general action of the machine ; and we shall 
 proceed to detail the structure of the several parts. 
 
 The type is composed, and made up into pages, in the usual manner ; the 
 pages are then placed in frames or gallies a, a, and fastened by the screws 
 at the ends, the shape and size of the gallies being adapted to the size of the 
 page it is intended to print. These gallies are attached to the four sides of 
 the central axis of the prism by the screw-clamps 1, the edges of the gallies 
 being mitred together. By relieving the clamps, the gallies can quickly be 
 removed, and others put in their places. The platen I i is composed of 
 four segments of cylinders, i i, which are attached to the different sides of the 
 central axis I, by means of screws, and these segments being proportioned 
 to the prism, will be the true figure for the platen to produce the required 
 motion, so that the surface, when it revolves, will, in all positions, preserve 
 an accurate contact with the surface of the types. The two wheels D, E, 
 which cause the prism and platen to accompany each other, are formed to 
 correspond with the two. Thus the upper wheel D is square, with its 
 
Al 
 
 yefle & JYrt'klgy, se,gj2.Strand 
 
AND MACHINIST. 
 
 303 
 
 angles rounded off, and the pitch or geometrical outline is exactly of the 
 same size as the square formed by the surfaces of the types. Tlie lower 
 wheel E is of the same shape as the platen, and its pitch-line the exact 
 size of the surface thereof. These wheels being cut into teeth, as the figure 
 shows, will turn each other round, and make their surfaces at the point of 
 contact exactly correspond in their motions, so as to have no sliding Or 
 slipping upon each other. To regulate the pressure upon the paper, the 
 bearings, in which the pivots of the platen are supported, can be elevated 
 by screws, 3, and its surface will press with more force upon the types ; but 
 that this may not derange the action of the wheels D and E, universal joints 
 are applied in their axles, at R. The inking-cylinder K is caused to pre- 
 serve its proper distance from the centre of the prism by wheels S, fixed 
 upon its axis, and resting upon shapes T, fixed upon the axis of the prism. 
 Each of the shapes, like the wheel D, has four flat sides, corresponding in 
 size with the surfaces of the types ; the angles are rounded to segments of 
 a circle from the centre ; the wheels S are of the same size as the inking- 
 cylinder, therefore, as they rest upon the shapes T, they prevent the ink- 
 cylinder passing upon the types with any more than a sufficient force to 
 communicate the ink without blotting. The inking-cylinder is turned round 
 by a cog-wheel N, upon the extremity of the axis of the prism, which is of 
 the same shape as the wheel D, and engages another wheel, W, upon the 
 end of the spindle of the inking-cylinder ; the latter wheel likewise gives 
 motion to the distributing-roller by a pinion/, and this again turns the ink- 
 roller by a third pinion g, fixed upon the end of its axis n, which is sup- 
 ported upon bearings B, B, in the frame. The pieces L, L, which support 
 the pivots of the distributing-roller and inking-cylinder, are fitted upon the 
 axis n of the inking-cylinder, so as to rise and fall upon its centre ; and the 
 distances of the rollers being thus kept invariably the same, their circum- 
 ferences are kept accurately in contact, to communicate the ink to each 
 other. The steel plate O, w'hich, as before mentioned, regulates the quantity 
 of ink that the roller N shall take round with it, is supported by a piece 
 extended across the fix6d frame B B. Tliere are pieces of metal fixed upon 
 this plate by thumb-nuts, which prevent the ink flowing off at the ends, and 
 they enter into grooves formed round the ink-roller N, near its ends. The 
 machine is put in motion by the handle with the fly-wheel H, and this has 
 a small wheel G, turning a large one F, upon the end of the axis b. 
 
 Tlie frame supporting the feeding-board P consists of two rails, X, fitted 
 upon the axis of the platen, and supported at the opposite ends by a brace 
 from the framing ; they sustain the pivots of the wheels d, d, for the chains ; 
 a: are tw-o rulers fixed at each side of the feeding-board, and forming a 
 lodgment for the ends of the ruler 2, which is attached to the blanket, and 
 it slides upon these when it is advanced by the chains. The spaces on the 
 platen between the segments i, i, are all filled up by pieces of wood, 
 except one, and in this space the ruler is received when it passes through 
 the machine. In the interval w’hen the spaces betw’een the types are passing 
 over the sheet, and therefore leave the margin between the pages of printing, 
 the paper is not held between the rollers; but to prevent it from slipping 
 during this interval, the blanket and paper are pressed down upon the 
 pieces of wood w’hich fill up in the platen between the segments i, i, by the 
 weight of small rollers or wires 4, supported by cocks 5, projecting from 
 the axis of the prism, and being fitted into the slits at the end of these cocks. 
 Tiie wires are at liberty to rise and fall by their own weight ; thus, when 
 they are at the upper part of the revolution, they fall into the spaces at the 
 angle of the prism, between the pages of the types, and thus escape the ink- 
 cylinder ; but when they are at the lower part of their revolution, they fell 
 
304 
 
 THE OPERATIVE MECHANIC 
 
 upon the paper, and press it with sufficient force upon the pieces of wood 
 in tile platen to carry the paper forward at the interval when the types do 
 not act upon it, and of course while the space between the pages of the 
 printing is passing through. 
 
 The operation of printing being very delicate, and requiring 
 great accuracy, the machine is provided with many adjust- 
 ments to make it act correctly, which are as follows : — The 
 segments ^, 2 , upon the platen -roller, are attached to the 
 central axis I, by three screws at each end ; the two middle 
 ones of these (represented with square heads) draw the seg- 
 ments down upon the central axis, whilst the others (which 
 are turned by a screw-driver) bear them off ; therefore, by 
 means of these screws, the segments can be accurately ad- 
 justed, till they are found by experiment to apply correctly 
 to the types, and make an equal impression on all parts of 
 the sheet. To render the whole impression greater or less, 
 the screws, 3, beneath the bearings of the platen- roller, are 
 turned as before mentioned. The degree of pressure with 
 which the ink-roller bears upon the types is regulated by 
 increasing or diminishing the size of the shapes T, which 
 support its weight. And to render these capable of adjust- 
 ment, each is composed of four pieces, marked 6, attached by 
 screws, J, to a central piece, or wheel, which is fixed upon 
 the axis ; and as the edges of these pieces form the outline 
 of the shape, they admit of being adjusted by other screws to 
 a greater or less distance from the centre, and of course may 
 be made to bear up the ink-cylinder till the pressure on the 
 types is equal throughout the whole surface, and sufficient 
 to supply the ink properly. The ink-cylinder is adjustable 
 as to its pressure against the distributing-roller, and for this 
 purpose the bearings /c, which support the cylinder, are fitted 
 upon the pieces L, to slide, being capable of regulation by 
 means of screws. In a similar manner, the distributing- 
 roller can be adjusted to a proper distance from the inking- 
 cylinder. The plate o can be adjusted for the distance from 
 the ink-roller N, by screws p, fastened by thumb-nuts ; this 
 regulates the degree of colour the impression will have, by 
 permitting the roller N to take more or less ink ; behind the 
 inking- cylinder K, a rubber, or scraper, is placed, to press 
 very lightly against the cylinder, and to prevent the ink 
 accumulating in rings round the cylinder, it is fitted upon 
 centres, and held up by a lever which is suspended by a 
 catch y, at the end of the piece L. This catch is withdrawn 
 when the machine is not at work, and then the scraper falling 
 dowui upon its centre, does not touch the cylinder. It is 
 
AND MACHINIST. 
 
 ‘>05 
 
 necessary that the wheels D and E should be placed upon 
 their axis, in such a position that their curvature will cor- 
 respond with the curvature of the prism and platen. For 
 this purpose the universal-joint R is fitted upon the axis I, 
 of the wheel, with a round part, that it may turn on it. A 
 piece of metal, r, is fixed fast upon the spindle /, and has 
 a hole in it for the reception of a tooth 5 , which is screwed 
 fast upon the universal -joint ; then two screws being tapped 
 through the sides of the piece r, press upon the end of a’, and 
 by forcing it either way, will adjust the wheel with respect 
 to the platen till they exactly correspond ; another similar 
 adjustment may be applied to the upper axis. 
 
 The manner of forming the ink and distributing rollers 
 with an elastic substance is worthy of particular notice. 
 Leather stuffed in the manner of a cushion was first used, but 
 did not succeed, because it became indented with the types ; 
 but after many trials, a composition of glue, mixed with 
 treacle, was found to answer perfectly. The roller is made 
 of a copper tube, covered with canvass, and placed in a 
 mould, which is a cylindrical metal tube, accurately bored, 
 and oiled withinside ; the melted composition is then poured 
 out into the space of the mould, and when cold, the whole is 
 drawn out of it, with the glue adhering to the copper tube, 
 and forming an accurate cylinder without any further trouble. 
 The composition will not hai’den niaterially by the exposure 
 to air, nor does it dissolve by the oil contained in the ink. 
 This machine is well adapted to print from stereotype plates, 
 which the universities have adopted for their bibles and prayer- 
 books. 
 
 Bramah’s bank-note press. 
 
 8. It w'as formerly the custom in the Bank of England to 
 fill up the number and dates of their notes in writing, till the 
 year 1809, w'hen the machine invented by Mr. Bramah was 
 adopted for this purpose. By this contrivance, the nmnbers 
 and dates were inserted not only in a more uniform and 
 elegant manner, but the labour was diminished to less than 
 one-sixth of what it was before. 
 
 The copper-plates from which the words of the notes are 
 printed, are double; that is, they tlirow off two notes at 
 a time upon one long piece of paper. This piece of paper, 
 containing two notes, is then put into the machine, which 
 prints upon them the number and dates in such a manner, that 
 the types change to the succeeding number, and that the 
 whole operation is performed without any attention on the 
 
 X 
 
306 
 
 THE OPERATIVE M^ECHANIC 
 
 part of the clerk. If one of the notes, for example, is N° 1,- 
 N® 1, and the other on the same paper N® 201 , N° 201, when 
 these are printed the machine alters itself to N® 2, N® 2, and 
 N® 202, N® 202 ; and in printing these, the types again change 
 to N® 3, N® 3, and N® 203, N® 203. The date and the word 
 London are cast in stereotype, and each machine is furnished 
 wicli one of these for every day in the year, and they of course 
 are changed every day. 
 
 The Bank of England has upwards of forty of these ma- 
 chines, the greater part of which are in constant use. It was 
 formerly considered sufficient labour for each clerk to fill up 
 the number twice repeated, and date twice repeated, 400 notes 
 per day ; but since the introduction of the machine, one clerk 
 has printed 1,300 double notes, which are equal to 2,600 
 single ones ; for though in the machine the double notes do 
 not require more labour than single ones, yet to fill up the 
 blanks by writing would occupy twice the time. 
 
 The mechanism by which this is effected is extremely 
 ingenious, and the principle is not limited to the numbering 
 of notes, but is equally applicable to the purpose of printing 
 any series of numbers which require continual alteration. We 
 have represented one of these machines, which is not, how- 
 ever, precisely the same as those in use, being only a single 
 one, and adapted for printing one note at once ; but we have 
 only to suppose it extended to twice the length, and furnished 
 with a double set of types, in order to fit it for printing two 
 notes at the same time. 
 
 In fig. 305, a perspective view of this machine will be found, and a section 
 of its parts at fig. 304, in both of which the same letters of reference are 
 employed. A solid piece of mahogany, A A, forms the base of the ma- 
 chine, and to this two iron plates, B B, are screwed, forming the sides of a 
 box, the front of which is removed in fig. 305, to exhibit the interior, and 
 the back is concealed between the mechanism. Across this box an axis, D, 
 is placed, having its pivots fixed into sockets which are fastened in the sides 
 of the frame, as is evident from' the figure. This axis carries the tympan E, 
 which gives the pressure to print off the note attached to it by screws ; and 
 a lever, F, is also fixed to the axis, by which the operator forces down the 
 tympan. The movable types, in which the principal novelty of the inven- 
 tion consists, are fitted into a series of brass circles, mounted upon an axis 
 G, extending across the centre of the frame. These circles are sufficiently 
 pointed out in the perspective view, by the numerals on the types fixed in 
 them ; they are ten in number, arranged in two lots of five each. 
 
 Each circle (shown more plainly at I, fig. 304) is divided into eleven 
 parts, and at each a rectangular notch is cut, to receive the types 1, 2, 3, 
 4 , 5, 6, 7, 8, 9, 0 and a blank type. Five of the circles, thus prepared, 
 being placed side by side, upon a fixed axis, G, on which they revolve 
 freely, are sufficient for printing any number less than 100,000 ; because, as 
 the circles can be turned about On their axis independent of each other. 
 
AND MACHINIST. 307 
 
 it is obvious that any combination of the above figures may be produced, 
 by bringing them to the highest point of the circle, which is the situation in 
 which they are to be placed when an impression is to be taken. This will 
 he more easily understood, if we consider that the brass plate which covers 
 the circles is put on its place, as represented in fig. 304, at a. This brass 
 plate has two apertures through it, to receive the two series of types 
 which project up a little above its surface when at the highest. In fig 305, 
 this plate is removed to exhibit the interior mechanism. 
 
 The circles are made to revolve by means of wheels, H, upon an axis 
 called the back axis, parallel to the axis of the circles. Tire end of it is seen 
 at I, fig. 305, projecting through the frame, and it carries three of the wheels 
 H, two of which are at the same distance apart as the two series of figure 
 circles to which they apply ; the third wheel is placed at an intermediate 
 distance between the other tw^o, and is acted upon by a catch or pallet 5, 
 fig. 304, attached to the axis of the tympan, by means of a joint, in such a 
 manner that it will strike against the highest tooth of the wheel H, and turn 
 it round one tooth. When the handle is lifted up rather beyond the 
 perpendicular, a stop a, fig. 305, upon the axis, meeting a projection a, 
 fig. 304, on the cover of the box, prevents it from moving farther; but 
 when the handle is returned down the position of the fig. 304, the pallet, 
 though it again meets the tooth of the wheel, gives way upon its joint, and 
 passes by without moving the wheel. In this manner it will be seen, that 
 every time the handle is pressed down to take an impression, in raising it up 
 again to place a fresh paper upon the tympan, the pallet moves the wheels II 
 one tooth, and as the teeth of these wheels engage the teeth of the figure 
 circles, a similar motion is communicated to them, bringing a fresh number 
 beneath the tympan, ready for printing. 
 
 It is to be observed, that the wheels H are of such a thickness, as to en- 
 gage only one of the five type circles at once, and their distance from each 
 other is such, that they take the same circle in the one series as they do in 
 the other. Now, by moving the back axis a small quantity endwise, it is 
 obvious that the wheel H can be brought to act upon any of the five circles, 
 or be placed in such a position as to be clear of them all. It is for this pur- 
 pose that the head I, fig. 305, comes through the frame of the machine; 
 for by means of this the axis can be moved on end, and by proper marks 
 upon it, it may be set to any of the five circles. In these positions it is con- 
 fined by a semicircular clip, which enters grooves turned round on the axis, 
 and deprives it of longitudinal motion, unless when the clip is raised. 
 This can be done by a nut coming through the back of the frame at K, 
 fig. 304. It has a short lever on the inside of it, which, when the nut is turned 
 round, raises up the clip, and releases the axis while it is set to the required 
 circle, and the clip being let fall into the proper groove, confines it from any 
 farther motion. 
 
 In order that all the circles may stop at the exact point, when the figure 
 is at the highest, and consequently when the surface of the figure will be 
 horizontal, an angular notch is made on the inside of the figure circles, 
 in the intermediate spaces betw'een each figure ; and at the lowest points of 
 the circle c, fig. 304, a movable pin is fitted into the fixed axis, with a 
 spring, which gives it a continual pressure downwards. The end of the pin 
 is formed spherical, and well polished, so that when the circle is turned 
 round it is forced into its hole in the axis ; but when another notch in the 
 circle presents itself, the pin presses out into it, and retains the circle with 
 a moderate force in its proper position, until the raising of the tympan, as 
 before described, overcomes the resistance of the pin, and turns the circle 
 round. By this contrivance the types always arrange themselves into a 
 
308 
 
 THE OPERATIVE MECHANIC 
 
 Straight line, after being turned round, without which the impression would 
 have a very disagreeable and irregular appearance. The tympan E, fig. 
 304, is composed of two parts ; a solid brass plate, against which a few 
 folds of cloth are placed and secured by the second part, which is a brass 
 traine covered with parchment, and attached to the former by four screws, 
 two of which appear at//, in fig. 305. 
 
 The bra;ss plate of the tympan is fastened to the leaf L, fig. 304, project- 
 ing from the axis by means of six screws. Two of these, only one of which, 
 A, can be seen in the figure, tend to throw the tympan from* the leaf ; while 
 the other four, which are arranged one on each side as the two former, 
 draw the tympan in and leaf together. By means of these screws thus act- 
 ing in opposition, the tympan can be adjusted so as to fall exactly parallel 
 upon the type, and communicate an equal pressure to all parts of the paper, 
 which is held against the tympan by means of a frisket of parchment 
 stretched on a frame which surrounds the tympan, and is movable on 
 joints at k k, fig. 305. The frisket is cut through as is represented by the 
 shaded parts in fig. 305, in order to expose the paper where it is to receive 
 the impression of the figures, and the No. before the figures, and also the ira- 
 pression of the date, year, and place. The type for these are formed in 
 stereotype, and fastened dowm upon the surface of the brass cover a, the 
 piece containing the day and month being changed every day. In order to 
 find the proper position which the paper should occupy upon the tympan, 
 two fine pins are fixed to project from it, and are received into holes made 
 in the brass cover; two dots are printed upon the note from the copper- 
 plates, and the pins being put through at these dots, ensure the figures, &c. 
 corning on their proper places. 
 
 The manner of using the machine is as follows t suppose the back axis 
 put so far on end as to be detached from all the circles ; the figure circles 
 arranged by hand, so that the blanks are all uppermost ; and the proper 
 stereotypes put in for the date. The back axis is then first set, so that its 
 wheels II may take the first five circles tow^ards the right hand, and by 
 moving the handle down almost to touch the type, and returning it up 
 again, the pallet moves the wheels H, and turns the two right-hand circles, 
 bringing up figure 1. The clerk now inks the type with a printer’s ball, 
 opens the frisket sheet L, fig. 305, on its hinges, and places the note 
 (already printed on the copper-plate press) against the tympan, the proper 
 place being determined by the two pins, and the dots printed on the note, 
 as before mentioned. He now shuts up the frisket sheet, in order to con- 
 fine the paper and keep it clean, except in the places where it is to be 
 printed ; then by pressing down the handle F, the impression is given ; and 
 on lifting it up again it moves the circles and brings up figure 2. The note 
 is now removed, a fresh one put in, and so on, the figure always changing 
 every time. 
 
 During this operation tlie twm right-hand circles act as units, and advance 
 one each time ; when 9 are printed in this manner and 0 comes up, the handle 
 is moved twice successively wuthout printing, which brings up a blank and 
 then a 1. Tlie back axis is moved, to act upon the second circle upon the 
 liglit hand, which now becomes the units, the first circle representing tens ; 
 by moving the handle «, without printing, figure 1 in the second circle 
 comes up, making 11, the next time 12, and so on to 19. The first circle 
 is now put forwards by hand, bringing up 2 and 0, on the second 20, then 
 moving the handle to pass the blank, produces 21, 22, &c. to 30, when the 
 first circle is again advanced, bringing up 4 ; in this manner the business 
 proceeds to 99. The back axis is now shifted to the third circle, which be- 
 comes units, the second tens,, and the third hundreds; the 0 and blank ot' 
 
I. 
 
 J5ANK KO TE jPKESS 
 
 From u04 tu 305 
 
 Pl.39 
 
 304- 
 
 3 05 
 k 
 
 2Tedc & Stodd^ se SSt JtnvU. 
 
AND MACHINIST. 
 
 309 
 
 'which are advanced to bring up 1, 0 is brought up in the second ; and the 
 machine itself brings up 0 in the third ; after printing this it changes to 101. 
 
 The process now continues through the successive hundreds in the same 
 manner as before till 999. The back axis is now shifted to the fourth circle, 
 and the three first must be advanced by hand when they require it. At 
 9999 the back axis is shifted to the fifth circle, and it will serve to 999,999, 
 beyond which it is not required to print. 
 
 PILE-ENGINE. 
 
 The pile-engine is a machine by which piles are driven 
 into the ground for the foundation of the piers of bridges, and 
 various other structures. 
 
 The method of driving a pile consists in drawing up a very 
 heavy weight, called a ram or hammer, and by disengaging it 
 from the machinery by which it was raised, letting it fall, by 
 the force of gravity, upon the head of the pile. In the most 
 simple machines the weight is drawn up by men pulling a 
 cord over a fixed pulley, and when it has attained a sufficient 
 height allowing the cord to slip from their hands, which per- 
 mits the weight to descend with considerable force. The two 
 best pile-engines that we have seen are those invented by 
 Mr. Vauloue and Mr. S. Bunce. 
 
 Mr. Vauloue’s pile-engine may be thus described. A, fig. 306, is a great 
 upright shaft or axle, on which are the great wheel B, and the drum C, 
 turned by horses joined to the bars S S. The wheel B turns the trundle X, 
 on the top of whose axis is the fly O, which serves to regulate the motion, as 
 well as to act against the horses, and to keep them from falling, when the 
 heavy ram Q is discharged to drive the pile P down into the mud in the 
 bottom of the river. The drum C is loose upon the shaft A, but is locked 
 to the wheel, B, by the bolt Y. On this drum the great rope, II H, is 
 wound ; one end of the rope being fixed to the drum, and the other to the 
 follower G, to which it is conveyed by the pulleys I and K. In the fol- 
 lower G is contained the tongs F, that take hold of the ram Q, by the 
 staple R, for drawing it up. D is a spiral or fusee fixed to the drum, on 
 which is wound the small rope, T, that goes over the pulley U, under the 
 pulley V, and is fastened to the top of the frame at 7. To the pulley block 
 V is hung the counterpoise W, which hinders the follower G from ac- 
 celerating as it goes down to take hold of the ram ; for, as the follower tends 
 to acquire velocity in its descent, the line T winds downwards upon the 
 fusee upon a larger and larger radius, by which means the counterpoise, W, 
 acts stronger and stronger against it; and so allows it to come down with only 
 a moderate and uniform velocity. The bolt Y locks the drum to the great 
 wheel, being pushed upward by the small lever 2, which goes through a 
 mortise in the shaft A, turns upon a pin in the bar 3, fixed to the great 
 wheel B, and has a w^eight 4, v/hich always tends to push up the bolt Y, 
 through the wheel into the drum. Lis the great lever turning on the axis »i, 
 and resting on the forcing bar 5, 5, which goes through a hollow in the shaft 
 A, and bears up the little lever 2. 
 
 By die horses going round, the great rope H is wound about the drum Cy 
 
THE OPERATIVE MECHANIC 
 
 310 
 
 and the ram Q is drawn up by the tongs F, in the follower G, until the 
 tongs come between the inclined planes E, which, by shutting the tongs at 
 the top, opens it at the foot, and discharges the rara, which falls down be- 
 tiyeen the guides b b, upon the pile P, and drives it by a few strokes as far 
 into the mud as it will go, after which the top part is sawed off close to the 
 mud by an engine for that purpose. Immediately after the ram is discharged, 
 the piece 6, upon the follower G, takes hold of the ropes a a, which raises 
 the end of the lever L, and causes its end, N, to descend and press down the 
 forcing bar 5, upon the little lever 2, which, by pulling down the bolt Y, 
 unlocks the drum C from the great wheel B, and then the follower being at 
 liberty comes down by its own weight to the ram, and the lower ends of 
 the tongs slip over the staple R, and the weight of their heads causes them 
 to fall outward and shut upon it. Then the weight 4 pushes up the bolt 
 Y into the drum, which locks it to the great wheel, and so the ram is 
 drawn up as before. 
 
 As the follower comes down, it causes the drum to turn backward, and 
 unwinds the rope from it, whilst the horses, great wheel, trundle, and fly, go 
 on with an uninterrupted motion ; and as the drum is turning backward, the 
 counterpoise, W, is drawn up, and its rope T, wound upon the spiral 
 fusee D. 
 
 There are several holes in the under side of the drum, and the bolt Y, 
 always takes the first of them that it finds, when the drum stops by the falling 
 of the follower upon the ram ; until which stoppage the bolt has not time to 
 slip into any of the holes. 
 
 The peculiar advantages of this engine are, that the weight 
 called the ram, or hammer, may be raised with the least 
 force ; that when it is raised to a proper height, it readily 
 disengages itself and falls with the utmost freedom ; that the 
 forceps or tongs are lowered down speedily, and instantly of 
 themselves again lay hold of the ram and lift it up. 
 
 This engine was placed upon a barge on the water, and so 
 was easily conveyed to any place desired. The ram was a 
 ton weight ; and the guides b b, by which it was let fall were 
 30 feet high. 
 
 Figs. 307 and 308 represent a side and front section of 
 Sunce’s pile-engine. 
 
 The chief parts are A, fig. 307, which are two endless ropes or chains, 
 (Connected by cross pieces of iron, B, (fig, 308,) corresponding with two 
 cross grooves diametrically opposite in the wheel C, (fig. 307,) into which 
 they are received, and by which means the rope or chain A is carried 
 round. F, II, K, is a side view of a strong wooden frame movable on the 
 axis H. D is awheel, over which the chain passes and turns within at the 
 top of the frame. It moves occasionally from F to G, upon the centre H, and is 
 kept in the position F, by the weight I, fixed to the end K. In fig. 309, L 
 is the iron ram, which is connected with the cross pieces by the hook m. 
 N is a cylindrical piece of wood suspended at the hook at O, which by 
 sliding freely up the bar that connects the hook to the ram, always brings 
 the hook upright upon the chain when at the bottom of the machine, in the 
 position of G P : see fig. 307. 
 
 When the man at S turns the usual crane- work, the ram being connected to 
 the chain and passing between the guides, is drawn up in a perpendicular 
 direction, and when it is near the top of the machine, the projecting bar Q, 
 

 
 ry 
 
 Jf rrie & sc 3jZ Sti-aji J 
 
AND MACHINIST. 
 
 311 
 
 of the hook, strikes against a cross piece of wood at R, fig. 307, and con- 
 sequently discharges the ram ; while the weight I of the movable frame 
 instantly draws the upper wheels into the position shown at F, and keeps 
 the chain free of the ram in its descent. The hook, while descending, is 
 prevented from catching the chain by the wooden piece R ; for that piece 
 being specifically lighter than the iron w'eight below, and moving with a 
 less degree of velocity, cannot come into contact with the iron till it is at the 
 bottom and the ram stops. It then falls, and again connects the hook with 
 the chain, which draws up the ram as before. 
 
 In this machine, as well as Vauloue’s, the motion of the 
 fii'st wheel is interrupted, so that very little time is lost in 
 the operation; with a .slight alteration it might be made to 
 work with horses. It has the advantage over Vauloue’s en- 
 gine in point of simplicity ; it may be originally constructed 
 at less expense, and is not so liable to be deranged. Both, 
 however, are ingenious performances, and part of their con- 
 struction might be advantageously introduced into other 
 machines. 
 
 The boring machine is employed for boring wooden 
 pipes for the conveyance of water, and for boring out the 
 metalline cylinders used in hydraubcs, and in pneumatic 
 engines. 
 
 The old and common method of boring, is to have a 
 horizontal axis turned round by a mill, at the end of which 
 a borer is fixed, and the cylinder is fastened down upon a 
 carriage, sliding in a direction parallel to its axis, and drawn 
 forwards to the borer by the descent of a weight. The ob- 
 jection to this method is, that any deviation from a rectilineal 
 motion in the carriage, will be transferred to the cylinder, 
 and cause it to be crooked ; and that the weight of the borer 
 and its axis acting on the lower side only of tlie cylinder, 
 causes it to cut away more at that part, and render the metal 
 of the cylinder of unequal thickness. This evil, however, 
 was, in some measure, obviated by a contrivance of Mr. 
 John Smeaton, which was a steel-yard mounted upon a mova- 
 ble wheel carriage, running within the cylinder. By suspend- 
 ing the weight of the cutter and boring-bar from it, the 
 machine was much improved, though still very imperfect. 
 
 A boring machine, for metal cylinders, which is not liable to any of 
 these sources of error, is constructed in the manner shown. Fig. 314 is a 
 perspective view of the machine in the action of boring out a cylinder for 
 a steam-engine, the other figures .explain the construction of its parts, and 
 
 BORING MACHINE. 
 
THE OPERATIVE MECHANIC 
 
 312 
 
 are drawn to a scale. In fig. 314, A A denote two oak ground sills, 
 which are firmly bolted down, parallel to each other, upon sleepers let into 
 . Ihe ground. At each end of these a vertical iron frame, B B, is erected, to 
 support the gudgeons at the end of a long cylindrical axis, D D, which is 
 turned round by the mill. The cylinder L L, which is to be bored, is fixed 
 immovable over tlie bar, and exactly concentric with it, A piece of cast- 
 iron KK, X-L, (figs. 310, 312, and 313,)’ called a cutter-head, slides upon 
 .the axis, and has fixed into it the knives or steelings / //, which perform 
 the boring. This cutter-head is moved along the bar by machinery, to be 
 hereafter described ; by means of which it is drawn or forced through the 
 cylinder, at the same time that it turns round with the axis D. The steel 
 cutters will necessarily cut away any protuberant metal which projects 
 within the cylinder, in the circle which they describe by their motion, but 
 cannot possibly take any more. 
 
 The cylinder is held down upon an adjustable framing, which is ready 
 adapted to receive a cylinder of any size within certain limits. Pieces of 
 iron, E E, are bolted down to the ground sills, having grooves through 
 them to receive bolts, which fasten down two horizontal pieces of cast-iron 
 I' F, at right angles to them. These horizontal pieces support four movable 
 upright standards GG, which include the diameter of the cylinder L L, 
 which is supported upon blocks, b b, below, and held fast by iron bands a a, 
 drawn by screws in the top of the standards G G. The cylinder is adjusted, 
 to be concentric with the axis D D, and held firmly in its place by 
 means of wedges driven under the blocks and the standards. 
 
 To explain the mechanism by which the cutters are advanced, we 
 must refer to figs. 311, 312, and 313, by the inspection of which it will 
 be seen that the axis D D is, in fact, a tube of cast-iron, hollow throughout. 
 Jt is divided by a longitudinal aperture cc, fig. 310, on each side. At the 
 ends of it is left a complete tube, to keep the two valves together. The 
 eutter-head K K, L L, consists of two parts ; of a tube K fitted upon the 
 axis D with the greatest accuracy, and of a cast-iron ring L L, fixed upon 
 K K by four wedges. On its circumference are eight notches, to receive 
 ihe cutters or steelings //, which are held in and adjusted by wedges. 
 The slider K is kept from slipping round with the axis, by means of two 
 short iron bars e e, which are put through to the axis, and received into 
 notches cut in the ends of the sliders K K. These bars have holes in the 
 middle of them to permit a bolt at the end of the toothed rack L to 
 pass through. A key is put through the end of the bolt, which, at the 
 same time, prevents the rack being drawn back, and holds the cross bars 
 e e in their places. The rack is moved by the teeth of a pinion N, and is 
 kept to its place by the roller O ; the axis of the pinion and roller being 
 .supported in a framing attached to the standard B B, as shown in a per- 
 spective view of the machine in fig. 314. The pinion is turned round by 
 a lever, put upon the square end of the axis, and loaded with the weight 
 P, that it may have a constant tendency to draw the cutter through the 
 cylinder. This lever is capable of being put on the square end of the 
 gxis either way, so as to force the rack back into the cylinder jf neces- 
 .sary. 
 
 In some boring machines, another contrivance, superior perhaps to what 
 we have now described, is employed to draw the cutter through the 
 rylinder. It consists of four small wheels, one of which is fixed at the 
 right-hand extremity, D, of the bar D D, fig. 314- Another pinion is 
 fastened on the extremity of an axis, analogous to the rack M, having at 
 its other extremity a small screw, which works in a female screw, fixed to 
 the cutter K K at #, fig. 310. Below the second pdnion is another, con- 
 
Frorrc <3/0 to 314. 
 
 ri.4i 
 
AND MACHINIST. 
 
 313 
 
 taining the same number of teeth, and fixed on a horizontal axis pa- 
 rallel to D D. At the other end of this axis is a fourth pinion, which is 
 drawn by the first pinion at the end of the hollow axis D D. The first 
 pinion has twenty-six teeth, the fourth thirty, and the second and third 
 may have any number, provided they are equal. As the axis D revolves, 
 the first pinion fixed on its extremity draws the fourth, which by means of 
 the third, fixed on the same axis with it, gives motion to the second. The 
 second pinion being fixed to an axis within D D, unscrews the screw at its 
 other extremity, and of course makes the cutter advance along the cylinder. 
 This screw has eight threads in an inch, and sixty turns of the axis are 
 requiied to cut one inch. 
 
 To introduce a cylinder into its place in the machine, it is necessary to 
 remove the upper braces, 1 1, of the bearings upon the standards B B ; 
 and by supporting the axis upon blocks placed under the middle of it, the 
 standard, with the pinion N, and roller frame, is removed by taking up the 
 nuts which fasten it to the ground sills A A, the rack M being supposed 
 previously withdrawn. A cutter-block L, of a proper size to bore out the 
 intended cylinder, is now placed upon the slider K, fig. 313, and wedged 
 fast. The cutter-head is then moved to the farther end of the axis, and 
 the cylinder lifted into its place. The standard B is returned, and the 
 whole machine brought to the state of fig. 314, the cylinder being, by 
 estimation, adjudged concentric with the axis D. Two bars of iron are 
 now wedged into the c c in the axis, and applied to the ends of the 
 cylinder; while the axis is turned round they act as compasses to prove 
 the concentricity of the cylinder. Small iron wedges are drawn round its 
 cylinder to adjust it with the utmost accuracy; and in this state the 
 cylinder is ready for boring. 
 
 The next operation is felling the cutters, which are 
 fastened into the block L by wedges, and adjusted by turn- 
 ing the axis round, to ascertain that they all describe the 
 same circle. The boring now commences by putting the 
 mill and axis in motion, and the machine requires no atten- 
 tion, except that the weight P is lifted up as often as it 
 descends by the motion of the cutters or steelings. When 
 the cutters are drawn down through the cylinder, they are 
 set to a circle a small quantity larger, and returned through the 
 cylinder a second time. For common work these operations 
 are sufficient ; but the best cylinders are bored many times, 
 in order to bring them to a proper cylindrical surface. The 
 last operation is turning the flanch n of the cylinder per- 
 fectly flat, by wedging a proper cutter into the head. This 
 is of great importance to ensure that the lid will fit perpen- 
 dicular to the axis of the cylinder. The cylinder is now 
 finished and removed. 
 
 The accuracy of this machine depends on the boring bar, 
 D D, being turned upon its ovm gudgeons ; and if it is turned 
 to the same diameter throughout, it will certainly be per- 
 fectly straight. While the axis is in the operation of turn - 
 ing, a piece of hard wood should be fitted into the grooves 
 of the cylinder. The slider K is first bored out, and 
 
314 
 
 THE OPERATIVE MECHANIC 
 
 afterwards ground upon the axis with emer}" to fit as true as 
 possible. 
 
 The elevation of a mill proper for moving two of these machines, is 
 represented in fig. 310. The pinion 30 is supposed to be on the axis of 
 a water-wheel, and turns the two wheels 60, 60, which have projecting 
 axes, with a cross-cut similar to the head of a screw, as is shown in the 
 figure. 
 
 The ends of the boring axes have similar notches, and by- 
 putting keys in between them, the motion may be commu- 
 nicated or discontinued at pleasure, by the removal of the 
 key. 
 
 FILE-CUTTING MACHINE. 
 
 There have been various contrivances for this purpose; 
 but the best we are acquainted with is described in the 
 Transactions of the American Philosophical Society y and is 
 as follows : 
 
 AAA A, fig. 315, is a bench of seasoned oak, the face of which 
 is planed very smooth. B B B B the feet of the bench, which should 
 be substantial. C C C C the carriage on which the files are laid, which 
 moves along the face of the bench AAA A, parallel to its sides, and 
 carries the files gradually under the edge of the cutter or chisel H H, 
 while the teeth are cut: this carriage is made to move by a contri- 
 vance somewhat similar to that which carries the log against the saw 
 of a saw-mill, as will be more particularly described. D D D are three 
 iron rods inserted into the ends of the carriage C C C C, and passing through 
 the holes in the studs E E E, which are screwed firmly against the ends of 
 the bench A A A A, for directing the course of the carriage C C C C, pa- 
 rallel to the sides of the bench. F F two upright pillars, mortised firmly 
 into the bench AAA A, nearly equidistant from each end of it, near the 
 edge, and directly opposite to each other. G the lever or arm which 
 carries the cutter H H, (fixed by the screw I,) and works on the centres of 
 two screws K K, which are fixed into the two pillars F F, in a direction 
 right across the bench A A A A. By tightening or loosening these screws, 
 the arm which carries the chisel may be made to work more or less steadily. 
 L is the regulating screw, by means of which the files may be made coarser 
 or finer ; this screw works in a stud M, which is screwed firmly upon the 
 top of the stud F ; the lower end of the screw L bears against the upper 
 part of the arm G, and limits the height to which it can rise. N is a steel 
 spring, one end of which is screwed to the other pillar F, and the other end 
 presses against the pillar O, which is fixed upon the arm G ; by its pressure 
 it forces the said arm upwards until it meets with the regulating screw L. 
 P is an arm with a claw at one end marked 6, the other end is fixed by a 
 joint into the end of the stud or pillar O, and, by the motion of the arm 
 G, is made to move the ratch-wheel Q. This ratch-wheel is fixed upon an 
 axis, which carries a small trundle-head or pinion R, on the opposite end ; 
 this takes into a piece S S, which is indented with teeth, and screwed firmly 
 against one side of the carriag'e C C C C ; by means of this piece motion 
 is communicated to the carriage. F is a clamp for fastening one end of 
 the file ZZ in the place or bed on which it is to be cut. V is another 
 
AND MACHINIST. 
 
 315 
 
 clamp or dog at the opposite end, which works by a joint W, firnily fixed 
 into the carriage C C C C. Y is a bridge, likewise screwed into the car- 
 riage, through which the screw X passes, and presses with its lower end 
 against the upper side of the damp V ; under which clamp the other end 
 of the file Z Z is placed, and held firmly in its situation while it is cutting 
 by the pressure of the said clamp V. 7 7 7 7 is a bed of lead, which is let 
 into a cavity formed in the body of the carriage, something broader and 
 longer than the largest size files ; the upper face of this bed of lead is 
 formed variously, so as to fit the different kinds of files which may be re- 
 quired. At the figures 2 2 are two catches, which take into the teeth of the 
 ratch-wheel Q, to prevent a recoil of its motion ; 3 3 is a bridge to support 
 one end, 4, of the axis of the ratch-wheel Q ; 5 a stud to support the other 
 end of the axis of that wheel. 
 
 When the file or files are laid in their place, the machine must be regu- 
 lated to cut them of the due degree of fineness, by means of the regulating 
 screw L ; which, by screwing farther through the arm M, wall make the 
 files finer, and, vice versa, by unscrewing it a little, will make them 
 coarser; for the arm G w'ill, by that means, have liberty to rise the higher, 
 which will occasion the arm P, with the claws, to move further along the 
 periphery of the ratch-wheel, and consequently communicate a more 
 extensive motion to the carriage C C C C, and make the files coarser. 
 
 When the machine is thus adjusted, a blind man may 
 cut a file with more exactness than can be done in the usual 
 method by the keenest sight j for by striking with a hammer 
 on the head of the cutter or chisel H H, all the movements 
 are set at work ; and by repeating the stroke with the ham- 
 mer, the files on one side will at length be cut ; then they 
 must be turned, and the operation repeated for cutting on 
 the other side. It is needless to enlarge much on the utility 
 or extent of this machine; for, on an examination, it will 
 appear to persons of but indifferent mechanical skill, that 
 it may be made to work by water as well as by hand, to cut 
 coarse or fine, large or small, files, or any number at a time ; 
 but it may be more particularly useful for cutting very fine 
 small files for watchmakers ; as they may be executed by 
 this machine with the greatest equality and nicety imagin- 
 able. As to the materials and dimensions of the several parts 
 of this machine, they are left to the judgment and skill of 
 the artist who may have occasion to make one ; only ob- 
 serving, that the whole should be capable of bearing a good 
 deal of violence. 
 
 RAMSDEN^S DIVIDING MACHINE. 
 
 This valuable instrument is the invention of Mr. Jesse 
 Ramsden, to whom the Commissioners of Longitude gave 
 the sum of 615 /., upon his entering into an engagement to 
 instruct a certain number of persons, not exceeding ten, in 
 
316 
 
 THE OPERATIVE MECHANIC 
 
 the method of making and using this machine, in the space 
 of two years, say, from the 28th October, 177*^? to 28th Oc- 
 tober, 1777 ; also binding himself to divide all sectants and 
 octants by the same engine, at the rate of three shillings for 
 each octant, and six shillings for each brass sectant, with 
 Nonius’s divisions to half minutes, for as long time as the 
 Commissioners should think proper to let the engine remain 
 in his possession. Of this sum 300/. were given to Mr. Rams- 
 den, as a reward for the usefulness of his invention; and 315/. 
 for his giving up the property of it to the Commissioners. 
 
 The following is the description of the engine given by 
 Mr. Ramsden, upon oath : 
 
 This engine consists of a large wheel of bell-metal, sup- 
 ported on a mahogany stand, having three legs, which are 
 strongly connected together by braces, so as to make it per- 
 fectly steady. On each leg of the stand is placed a conical 
 friction-pulley, whereon the dividing wheel rests ; to prevent 
 the wheel from sliding off the friction-pullies, the bell-metal 
 centre under it turns in a socket on the top of the stand. 
 
 The circumference of the wheel is ratched or cut (by a 
 method which will be described hereafter) into 2160 teeth, 
 in which an endless screw acts. Six revolutions of the screw 
 will move the wheel a space equal to one degree. 
 
 Now a circle of brass being fixed on the screw-arbor, 
 having its circumference divided into sixty parts, each divi- 
 sion will, consequently, answer to a motion of the wheel of 
 ten seconds, six of them will be equal to a minute, &c. 
 
 Several different arbors of tempered steel are truly 
 ground into the socket in the centre of the wdieel. The 
 upper parts of the arbors, that stand upon the plane, are 
 turned of various sizes, to suit the centres of different pieces 
 of work to be divided. 
 
 When any instrument is to be divided, the centre of it is 
 very exactly fitted on one of these arbors ; and the instru- 
 ment is fixed down to the plane of the dividing wheel, by 
 means of screws, which fit into holes made in the radii of 
 the w’heel for that purpose. 
 
 The instrument being thus fitted on the plane of the wheel, 
 the frame which carries the dividing point is connected at 
 one end by finger-screw^s, with the frame which carries the 
 endless-screw; while the other end embraces that part of 
 the steel arbor which stands above the instrument to be 
 divided, by an angular notch in a piece of hardened steel ; 
 by this means both ends of the frame are kept perfectly 
 steady and free from any shake. 
 
AT^U MACHINIST. 
 
 317 
 
 The frrane carrying the dividing-point or tracer, is made 
 to slide on the frame which carries the endless-screw to any 
 distance from the centre of the wheel, as the radius of the 
 instrument to be divided may require, and may be there 
 fastened by^ tightening two clumps 5 and the dividing-point 
 or tracer, being connected with the clumps by the double- 
 jointed frame, admits a free and easy motion towards or 
 from the centre for cutting the divisions, without any lateral 
 shake. 
 
 From what has been said, it appears that an instrument 
 thus fitted on the dividing-wheel, may be moved to any angle 
 by the screw and divided circle on its arbor ; and that this 
 angle may^ be marked on the limb of the instrument with the 
 greatest exactness by the dividing-point or tracer, which can 
 only move in a direct line tending to the centre, and is alto- 
 gether freed from those inconveniences that attend cutting 
 by means of a straight edge. This method of drawing lines 
 'will also prevent any error that might arise from an expan- 
 sion or contraction of the metal during tfie time of dividing. 
 
 The screw- frame is fixed on the top of a conical pillar, 
 which turns freely round its axis, and also moves freely 
 towards or from the centre of the w'heel, so that the screw- 
 frame may be entirely guided by the frame wdiich connects it 
 with the centre: by this means any eccentricity of the wheel 
 and the arbor would not produce any error in the dividing ; 
 and by a particular contrivance, (which will be described 
 hereafter,) the screw when pressed against the teeth of the 
 'wheel always moves parallel to itself ^ so that a line joining 
 the centre of the arbor and the tracer continued will always 
 make equal angles with the screw. 
 
 Fig. 316 represents a perspective view of the engine. 
 
 Fig. 317 is a plan of which fig. 318 represents a section on the line IIA. 
 
 The large wheel A is 45 inches in diameter, and has 10 radii, each being 
 supported by edge-bars, as represented in fig. 318. These bats and radii 
 are connected by a circular ring B, 24 inches in diameter and 3 inches deep ; 
 and, for greater strength, the whole is cast in one piece in bell-metal. 
 
 As the whole weight of the wheel A rests on its ring B, the edge-bars 
 are deepest where they join it ; and from thence their depth diminishes, 
 both towards the centre and circumference, as represented in fig. 318 
 
 The surface of the wheel A was worked very even and fiat, and its cir- 
 cumference turned true. The ring C, of fine brass, was fitted very exactly 
 on the circumference of the wheel ; and was fastened thereon witli screws, 
 which, after being screwed as tight as possible, were well rivetted. The 
 face of a large chuck being turned very true and flat in the lathe, the flat- 
 tened surface A, fig. 318, of the wheel, was fastened against it with hold- 
 fasts ; and the two surfaces and circumference of the ring C, a hole through 
 the centre and the plane part round 6, and the lower edge of the ring B, 
 were turned at the same time. 
 
 D is a piece of hard bell-metal, having a hole, which receives the steel 
 
318 
 
 THE OPERATIVE MECHANIC 
 
 arbor «/, made very straight and true. This bell-metal was turned very true 
 on an arbor ; and the face, which rests on a wheel at 6, was turned very 
 flat, so that the steel arbor d might stand perpendicular to the plane of the 
 wheel; this bell-metal was fastened to the wheel by six steel screws, 
 
 A brass socket Z is fastened on the centre of the mahogany stand, and 
 receives the lower part of the bell-metal piece D, being made to touch the 
 bell-metal in a narrow part near the mouth, to prevent any obliquity of the 
 wheel from bending the arbor ; good fitting is by no means necessary here ; 
 since any shake in this socket will produce no bad effect, as will appear 
 hereafter when we describe the cutting-fi-ame. 
 
 The wheel was then put on its stand, the lower edge of the ring B, 
 figs. 316, 317, and 318, resting on the circumference of three conical friction 
 pulleys W, to facilitate its motion round its centre. The axis of one of 
 these pulleys is in a line joining the centre of the wheel and the middle of 
 the endless-screw, and the other two placed so as to be at equal distances 
 from each other. 
 
 Fig. 316 is a block of wood strongly fastened to one of the legs of the 
 stand ; the piece g is screwed to the upper side of the block, and has half- 
 holes, in which the transverse axis A, fig. 319, turns; the half-holes are kept 
 together by the screws i. 
 
 The lower extremity of the conical pillar P, figs. 316 and 319, terminates 
 in a cylindrical steel pin k, fig. 319, which passes through and turns in the 
 transverse axis /^, and is confined by a check and screw. 
 
 To the upper end of the conical pillar is fastened the frame G, fig. 319, 
 in which the endless-screw turns; the pivots of the screw are formed in the 
 manner of two frustrums of cones joined by a cylinder, as represented at X, • 
 fig. 320. These pivots are confined between half-holes, which press only 
 on the conical parts, and do not touch the cylindric parts ; the half-holes 
 are kept together by screws a, which may be tightened at any time, to 
 prevent the screw from shaking in the frame. 
 
 On the screw-arbor is a small wheel of brass K, figs. 316, 317, 319, and 
 320, having its outside edge divided into 60 parts, and numbered at every 
 sixth division with 1, 2, &c. to 10. The motion of this wheel is shown by 
 the index figs. 319 and 320, on the screw-frame G. 
 
 H, fig. 316, represents a part of the stand, having a parallel slit in the 
 direction towards the centre of the wheel, large enough to receive the upper 
 part of the conical brass pillar P, which carries the screw' and its frame ; 
 and as the resistance, when the wheel is moved by the endless-screw, is 
 against the side of the slit H which is towards the left hand, that side of 
 the slit is faced with brass, and the pillar is pressed against it by a steel 
 spring on the opposite side ; by this means the pillar is strongly supported 
 laterally, and yet the screws may be easily pressed from or against the 
 circumference of the wheel, and the pillar will turn freely on its axis to take 
 any direction given it by the frame L. 
 
 At each corner of the piece I, fig. 319, are screw's «, of tempered steel, 
 having polished conical points ; two of them turn in conical holes in the 
 screw-frame near o, and the points of the other tw'o screws turn in the 
 boles in the piece Q; the screws p are of steel, which being tightened, 
 prevent the conical pointed screws from unturning when the frame is 
 moved. 
 
 L, figs. 316, 317, and 321, is a brass frame, which serves to connect the 
 endless-screw, its frame, &c. with the centre of the wheel ; each arm of this 
 frame is terminated by a steel screw, that may be passed through any of 
 the holes g, in the piece Q, fig. 319, as the thickness of the work to be 
 divided on the wheel may require, and are fastened by the finger-nuts 
 figs. 316 and 317. 
 
AND MACHINIST. 
 
 319 
 
 At the end of this frame is a flat piece of tempered steel h, fig. 321^ 
 wherein is an angular notch ; when the endless-screw is pressed against the 
 teeth of the circumference of the wheel, which may be done by turning the 
 finger-screw S, figs. 316 and 317, to press against the spring t, this notch 
 embraces and presses against the steel arbor d. This end of the frame may 
 be raised or depressed by moving the prismatic slide fig. 317, whicli may 
 be fixed at any height by the four steel screws o, figs. 316, 317, and 321. 
 
 The bottom of this slide has a notch K, figs. 316 and 321, whose plane is 
 parallel to the endless-screw, and by the point of the arbor </, fig. 318, 
 resting in this notch, this end of the frame is prevented from tilting. The 
 screw S, figs. 316 and 317, is prevented from unturning, by tightening tlie 
 finger-nut w. 
 
 The teeth on the circumference of the wheel were cut by 
 the following method : 
 
 Having considered what number of teeth on the circum- 
 ference would be most convenient, which in this engine is 
 2160, or 360 multiplied by 6, 1 made two screws of the same 
 dimension of tempered steel, in the manner hereafter de- 
 scribed, the interval between the threads being such as I 
 knew by calculation would come within the limits of what 
 might be turned of the circumference of the wheel : one of 
 these screws, which was intended for ratching or cutting the 
 teeth, was notched across the threads, so that the screw, 
 when pressed against the edge of the wheel and turned 
 round, cut in the manner of a saw. Then having a segment 
 of a circle a little greater than 60 degrees, of about the same 
 radius with the wheel, and the circumference made true, 
 from a very fine centre, I described an arch near the edge, 
 and set off the chord of 60 degrees on this arch. This seg- 
 ment was put in the place of the wheel, the edge of it was 
 ratched, and the number of revolutions and parts of the 
 screw contained between the interval of the 60 degrees were 
 counted. The radius was corrected in the proportion of 
 360 revolutions, which ought to have been in 60 degrees, to 
 the number actually found ; and the radius, so corrected, was 
 taken in a pair of beam-compasses ; while the wheel was on 
 the lathe, one foot of the compasses was put in the centre, 
 and with the other a circle was described on the ring; then 
 half the depth of the threads of the screw being taken in 
 dividers, vras set from this circle outwards, and another 
 circle was described cutting this point; a hollow was then 
 turned on the edge of the wheel, of the same curvature as 
 that of the screw at the bottom of the threads, the bottom 
 of tliis hollow was turned to the same radius or distance from 
 the centre of the wheel, as the outward of the two circles 
 before-mentioned. 
 
 The wheel was now taken off the lathe, and the bell-metal 
 
320 
 
 THE OPERATIVE MECHANIC 
 
 piece D, fig. 318, was screwed on as before directed, whicli 
 after this ought not to be removed. 
 
 From a very exact centre a circle was described on the ring C, figs. 3i6, 
 317, and 318, about four-tenths of an inch within where the bottom of tlia 
 teeth would come. This circle was divided with the greatest exactness I 
 was capable of, first into five parts, and each of these into three. These 
 parts were then bisected four times, (that is to say,) supposing the w'hole 
 circumference of the wheel to contain 2160 teeth, this being divided into 
 five parts, each would contain 432 teeth ; which being divided into three 
 parts, each of them would contain 144; and this space bisected four times 
 would give 72, 36, 18, and 9 ; therefore each of the last divisions would 
 contain nine teeth. But, as I was apprehensive some error might arise 
 from quinquesection and trisection, in order to examine the accuracy of the 
 divisions, I described another circle on the ring C, (fig. 322,) one-tenth of 
 an inch within the former, and divided it by continual bisections, as 2160, 
 1080, 540, 270, 135, 67^, and 33^; and as the fixed wire (to be described 
 presently) crossed both the circles, I could examine their agreement at 
 every 135 revolutions; (after ratcliing, could examine it at every 334 ;) but 
 not finding any sensible difference between the two sets of divisions, I, for 
 ratching, made choice of the former ; and, as the coincidence of the fixed wire 
 with an intersection could be more exactly determined than with a dot or 
 division, I therefore made use of intersections in both circles before described. 
 
 The arms of the frame L, fig. 322, were connected by a thin piece of brass 
 of three-fourths of an inch broad, having a hole in the middle of four-tenths 
 of an inch in diameter ; across this hole a silver wire was fixed exactly in a 
 line to the centre of the wheel ; the coincidence of this wire with the inter- 
 sections was examined by a lens seven-tenths of an inch focus, fixed in a tube 
 which was attached to one of the arms L* Now a handle or winch being 
 fixed on the end of the screw, the division marked 10, on the circle K,was 
 set to its index, and, by means of a clamp and adjusting-screw for that pur- 
 pose, the intersection marked 1 on the circle C was set exactly to coincide 
 with the fixed wire; the screw was then carefully pressed against the 
 circumference of the wheel, by turning the finger-screw S, then, removing 
 the clamp, I turned the screw by its handle nine revolutions, till the inter- 
 section marked 240 came nearly to tlie wire ; then, unturning the finger- 
 screw S, 1 released the screw from the wheel, and turned the wheel back 
 till the intersection marked 2 exactly coincided with the wire; and, by 
 means of the clamp before-mentioned, the division 10 on the circle being 
 set to its index, the screw was pressed against the edge of the w heel by the 
 finger-screw S; the clamp wire removed, and the screw turned nine revolu- 
 tions till the intersection marked 1 nearly coincided with the fixed wire ; the 
 screw was released from the wheel by unturning the finger-screw S as 
 before ; the wheel was turned back till the intersection 3 coincided with 
 the fixed wire; the division 10 on the circle being set to its index, the 
 screw was pressed against the wheel as before, and the screw w'as turned 
 nine revolutions, till the intersection 2 nearly coincided with the fixed wire, 
 and the screw was released ; and I proceeded in this manner till the teeth 
 were marked round the whole circumference of the wheel. This was 
 repeated three times round, to make the impression of the screw deeper. 
 I then ratched the wheel round continually in the same direction without 
 ever disengaging the screw ; and, in ratching the wheel about 300 times 
 round, the teeth were finished. 
 
 * The intersections are marked for the sake of illustration, thouc'h properly 
 invisible, they lying under the brass plate. 
 
fl4Z 
 
 BlVIBmG MAC Mm® 
 From. 315 to 319 
 
AND MACHINIST. 
 
 321 
 
 It is evident if the circumference of the wheel were even 
 one tooUi or ten minutes greater than the screw would 
 require, 'this error would in the first instance be reduced to 
 -rVv part of a revolution, or two seconds and a half ; and these 
 errors or inequalities of the teeth be equally distributed 
 round the wheel at the distance of nine teeth from each 
 other. Now, as the screw in ratchiiig had continually hold 
 of several teeth at the same time, and these constantly 
 changing, the above-mentioned inequalities soon corrected 
 themselves, and the teeth were reduced to a perfect equality. 
 The piece of brass which carries the wire w'as now taken 
 away, and the cutting-screw w^as also removed, and a plain 
 one (hereafter described) put in its place ; on one end of the 
 screw is a small brass circle, having its edge divided into 
 sixty equal parts, and numbered at every sixth division, as 
 before mentioned. 
 
 On the other end of the screw is a ratchet-wheel c, having sixty teeth, 
 covered by the hollowed circle d, fig. 320, which carries two clicks that 
 catch upon the opposite sides of the ratchet when the screw is to be moved 
 forwards. The cylinder S turns on a strong steel arbor F, which passes 
 through and is firndy screwed to the piece Y ; this piece, for greater firm- 
 ness, is attached to the screw-frame G, fig. 319, by tne braces v ; a spiral 
 groove or thread is cut on the outside of the cylinder S, which serves both 
 for holding the string, and also giving motion to the lever J on its centre, 
 by means of a steel tooth n, that works between the threads of the spiral. 
 To the lever is attached a strong steel pin w, on which a brass socket, r, 
 turns; this socket passes through a slit in the piece p, and maybe tightened 
 in any part of the slit by the finger-nut/; this piece serves to regulate the 
 number of revolutions of the screw for each tread of the treadle R. 
 
 T, fig. 316, is a brass box containing a spiral spring; a strong gut is 
 fastened and turned three or four times round the circumference of this box; 
 the gut then passes several times round the cylinder S, and from thenca 
 down to the treadle R, fig. 316. Now, when the treadle is pressed down, 
 the string pulls the cylinder S round its axis, and the clicks catching hold 
 of the teeth on the ratchet carry the screw round with it, till, by the tooth n 
 working in the spiral groove, the lever J, fig. 319, is brought near the 
 wheel ft, and the cylinder stopped by the screw-head, a, striking on the top 
 of the .ever J ; at the same time the spring is wound up by the other end of 
 the girt passing round the box T, fig. 316. Now, when the foot is taken 
 oft the treadle, the spring, unbending itself, pulls back the cylinder, the 
 clicks leaving the ratchet and screw at rest till the piece t strikes on the end 
 of the piece p, fig. 316; the number of revolutions of the screw at each 
 tread is limited by the number of revolutions the cylinder is allow'ed to 
 turn back before the stop strikes on the piece 
 
 When the endjess-screw w’as moved round its axis with a considerable 
 velocity, it would continue that motion a little after the cylinder, figs. .316 
 and 319, was stopped; to prevent this, the angular lever 77 was made, 
 that when the lever J comes near to stop the screw a:, it, by a small cham- 
 fer, presses dowm the piece k of the angular lever ; this brings the other 
 end, 7 j, of the same lever forwards, and stops the endless-screw by the steel 
 pm, iM, striking upon the top of it : the foot of the lever is raised again by 
 small spting pressing on the brace v 
 
 Y 
 
322 
 
 THE OPERATIVE MECHANIC 
 
 D, two clamps, connected by the piece a, slide one on each arm of the frame 
 L, figs. 316, 317, and 321, and may be fixed at pleasure by the four finger- 
 screws f, which press against the steel springs to avoid spoiling the arms ; 
 the piece q is made to turn without shake between two conical pointed 
 screws /, which are prevented from unturning by tightening the finger- 
 nuts N. 
 
 The piece fig. 321, is made to turn on the piece by the conical 
 pointed screws, a, resting in the hollow centres e. 
 
 As there is frequent occasion to cut divisions on inclined planes, for that 
 purpose the piece, 7, in which the tracer is fixed, has a conical axis at each 
 end, which turn in half-holes ; when the tracer is set to any inclination, it 
 may be fixed there by tightening the steel screws /3. 
 
 Description of the engine by which the endless-screw of the dividing-engine 
 
 was cut. 
 
 Fig. 324 represents this engine of its full dimensions, seen from one side. 
 
 Fig. 323, the upper side of the same, as seen from above. 
 
 A, represents a triangular bar of steel, to which the triangular holes in 
 the pieces B and C are accurately fitted, and may be fixed on any part of 
 the bar by the screws D. 
 
 E is a piece of steel whereon the screw is intended to be cut ; which, 
 after being hardened and tempered, has its pivots turned in the form of two 
 frustrums of cones, as represented in the drawings of the dividing-engine, 
 fig. 320. These pivots were exactly fitted to the half-holes F and T, which 
 were kept together by the screws z. 
 
 H represents a screw of untempered steel, having a pivot I, which turns in 
 the hole h ; at the other end of the screw is a hollow centre, which receives 
 the hardened conical point of the steel pin m. When this point is sufficiently 
 pressed against the screw, to prevent its shaking, the steel pin may be fixed 
 by tightening the screws Y. 
 
 N IS a cylindric nut movable on the screw H ; which, to prevent any 
 shakes, may be tightened by the screws O. This nut is connected with the 
 saddle-piece P, by means of the intermediate universal joint W, through 
 which the arbor of the screw H passes. A front view of this piece, with a 
 section across the screw-arbor, is represented at X. This joint is connected 
 with the nut by means of two steel slips S, which turn on pins between the 
 cheeks T, on the nut N. Tlie other ends of these slips, S, turn in like man- 
 ner on pins a ; one axis of this joint turns in a hole in the cock b, which is 
 fixed to the saddle-piece ; and the other turns in a hole d, made for that 
 purpose in the same piece on which the cock b is fixed . By this means, when 
 the screw is turned round, the saddle-piece will slide uniformly along the 
 triangular bar A. 
 
 K is a small triangular oar of well-tempered steel, which slides in a groove 
 of the same form on the saddle-piece P. The point of this bar or cutter is 
 formed to the shape of the thread intended to be cut on the endless-screw. 
 When the cutter is set to take proper hold of the intended screw, it may 'be 
 fixed by tightening the screws c, which press the two pieces of brass upon it. 
 
 Having measured the circumference of the dividing-wheel, I found it 
 would require a screw about one thread in a hundred coarser than the guide- 
 screw arbor H, and tliat on the stub E, on which the screw was to be cut,, 
 were proportioned to each other to produce that effect, by giving the wheel 
 L 198 teeth, and the wheel Q 200. These wheels communicated with each 
 other by means of the intermediate wheel R, which also served to give the 
 threads on the two screws the same direction. 
 
 The saddle-piece P js confined on the bar A by means of the pieces gf 
 and may be made to slide with a proper degree of tightness by the screv/s n 
 
319 
 
 Fj'om 920 to 330 
 
 319 
 
 £” 
 
 319, 
 
 329 
 
 f 
 
 f'm 
 
 
 y 
 
 3 20 
 
 £X y 
 
 3 2S 
 
 319 
 
 yc^t StDcklen^ Svtmd 
 
AND MACHINIST. 
 
 S23 
 
 LATHES AND TURNING APPARATUS. 
 
 The lathe is a very useful engine for turning wood^ ivory, 
 metals, and other materials. 
 
 The common lathe is composed of two wooden cheeks or 
 sides, parallel to the horizon, having a groove or opening be- 
 tween ; perpendicular to these are two other pieces, called 
 puppets^ made to slide between the cheeks, and to be fixed 
 down at any point at pleasure. These have two points, be- 
 tween which the piece to be turned is sustained ; the piece is 
 turned round backwards and forwards by means of a string 
 put round it and fastened above to the end of a pliable pole, 
 and underneath to a treadle or board moved with the foot. 
 There is also a rest which bears up the tool, and keeps it 
 steady. 
 
 We shall now proceed to give Mr. J. Farey’s description of 
 the improved lathes manufactured by Mr, Hem'll Maudslay, 
 of Margaret- street. Cavendish-square. 
 
 A, fig. 325, is the great wheel, with four grooves on the rim ; it is worked 
 by a crank B, and treadle C, in the common way ; the catgut which goes 
 round this wheel passes also round a smaller wheel D, called the mandrel, 
 which has four grooves on its circumference, of different diameters, forgiving 
 it different velocities, corresponding with the four grooves on the great 
 wheel A. In order to make the same band suit, when applied to all the 
 different grooves on the mandrel D, the wheel A can be elevated or depressed 
 by a screw, a, and another at the other end of the axle ; and the connecting 
 rod, C, can be lengthened or shortened by screwing the hooks at each end of 
 it further out of, or into it. The end M, fig. 326, of the spindle of the 
 mandrel D, is pointed, and works in a hole in the end of a screws, put 
 through the standard E, fig. 325 ; the other end of the bearing F, fig. 326, 
 is conical, and works in a conical socket in the standard F, fig. 325, so that, 
 by tightening up the screw in E, the conical end, F, may at any time be 
 made to fit its socket; the puppet G has a cylindric hole through its top to 
 receive the polished pointed rod c?, which is moved by the screw e, and 
 fixed by the screw /; the whole puppet is fixed on the triangular prismatic 
 bar H, by a clamp, fig. 332, the two ends of which, a, b, are put through 
 holes, bj in the bottom of the puppet under the bar, and the w'hole is fixed 
 by the screw c pressing against it ; by this means the puppet can be taken 
 off the bar without first taking off the standard I, as in the common lathes ; 
 and the triangular bar is found to be far preferable to the double rectangular 
 one in common use. The resty is a similar contrivance; it is in three 
 pieces ; see figs. 327, 328, and 329. Fig. 328 is a piece, the opening, «, b, c, in 
 which, is laid upon the bar H, fig. 325 ; the four legs, dddd, of fig. 329, are 
 then put up under the bar (into the recesses in fig. 328, which are made to 
 receive them) so that the notches 'm d d d d may be level with the top of fig. 
 328 ; the two beads, ef, in fig. 327, are then slid into the notches in the top 
 oi dd d d, fig. 328, to keep the whole together; the groove i is to receive a 
 corresponding piece on e/, fig. 327, to steady it; the whole of fig 327 has 
 metallic cover, to keep the chips out of the grooves. It is plain that, by tighW 
 
THE OPERA nVK MECHANIC 
 
 :)2‘i 
 
 caing th^ screw h, in the bottom of fig. 329, the whole will be fixed and pre- 
 vented from sliding along the bar H, and fig. 327 from sliding in a direction 
 perpendicular to the bar; the piece /, fig. 327, on which the tool is laid, can 
 be raised or lowered at pleasure, and fixed by a screw, m. On the end, n, of 
 the spindle P, figs. 325 and 326, is screwed occasionally an universal chuck 
 for holding any kind of work which is to be turned. (See fig. 330.) A is the 
 female screw to receive the screw n, fig. 325 ; near the bottom of the screw 
 A is another screw, B B, which is prevented from moving endways by a col- 
 lar in the middle of it fixed to the screw A ; one end of the screw B B is 
 cut right-handed, and the other left-handed ; so that by turning the screw 
 one way, the two nuts, E F, will recede from each other, or by turning it the 
 contrary way, they will advance towards each other ; the two nuts, E F, 
 pass through an opening in the plate C, and project beyond the same, carrying 
 jaws, like those of a vice, by which the subject to be turned is to be held. 
 
 For turning faces of wheels, hollow work, &c. where great accuracy is 
 wanted, Mr. Maudslay has contrived a curious apparatus, which he calls a 
 slide-tool, represented by fig. 331, where E E E is the opening to receive 
 the bar H, fig. 325, and it is fixed by the clamp, fig. 332, as before de- 
 scribed ; the tool for cutting, &c. is fixed into the two holders b by by their 
 screws ; these holders are fastened to a sliding plate a, which can be moved 
 backwards and forwards by the screw c, causing the tool to advance or re- 
 cede ; fig. 333 represents the under side (turning upwards) of the part A A, 
 in which the screw c is seen fixed at each end, and the nut rf, which is at- 
 tached to the underside of the plate a, working upon it. When it is neces- 
 sary, as in the turning of the inside of cones, &c. that the tool should not 
 be parallel to the spindle P, the screw c, and another similar one behind, 
 must be loosened, _the tool set at the proper angle, and then be screwed tight 
 again. In order to make the piece A A move truly when it is turned 
 round, there is a hole/, fig. 333, to receive a knob gy fig. 338, upon the 
 plate B, which acts as a centre, and keeps it in its place ; there are three 
 holes on each side in the plate B, fig. 336, to put the screw e in at different 
 tiines, thus giving to the tool a greater range than the circular openings S S 
 will admit. 
 
 The part E E E E, represented separately, and inverted, in fig. 334, is of 
 cast-iron, and has a screw, 4, working in it, similar to fig. 333 ; the nut of this 
 screw is attached to the bottom of the slide H, fig. 335, at ty which slides 
 in the groove z, figs. 331 and 334; at one end of it is a box containing a 
 screw my to be hereafter described, and at the other is a frame of brass K K. 
 Near the same end of the slide is a pin L, projecting above the plate, which 
 is put through an opening, / in fig. 336, to steady it, while the other end C, 
 of fig. 336, is put through an opening M, in the box D, fig. 335. In the 
 part C is an oblique slit 1 1, to receive a stub which projects from the bot- 
 tom of the nut n, worked by the screw m, fig. 335 ; by this arrangement it is 
 obvious that if the screw m is worked, the stub of the nut Ji, acting against 
 the slide of the slit 1 1, as an inclined plane, will move it either backwards or 
 forwards through the opening M ; a metal cover »•, fig. 338, is occasionally 
 put over the opening for the nut n, and screw m, to prevent the chips from 
 falling in. 
 
 Near the four corners of the frame, fig. 336, are four small projections, ooooy 
 with inclined sides, which fit into the four openings p p p py oi figs. 337 and 
 331 ; these openings are cut out in two brass plates, wliich are screwed on at 
 right angles to the plate B B, figs. 331 and 337 ; the ends, qq q q, of these 
 plates slide between the edges of the frame K K and the box D, so as to 
 prevent any other motion than a vertical one. When this slide tool is used, 
 the puppet G is to be removed or pushed back further from F, and the tool 
 
from 331 to 3 40 
 
 yade i SvytJdtf 4< ifff Srrtnl 
 
AND MACHINIST. 
 
 325 
 
 is put upon the bai II, fig. 325, and fixed in the place of the rest j, by the 
 elamp, hg. 332, the distance from the centre n is adjusted by the. screw h, 
 which moves the slide, fig. 335, in the grooves i, figs. 331 and 334, with the 
 whole apparatus upon it; by the screw m, figs. 331 and 335, as before de« 
 scribed, the slide, %. 336, may be moved in a direction perpendicular to the 
 bar H, fig. 325, and its projections o o, acting against the slits pp, figs. 331 
 and 337, as inclined planes, will raise or lower the plate B, as is required. 
 
 The tool, which has been before fixed in the holders b b, can be set at the 
 proper angle by loosening the screw e, as previously described ; and, lastly, 
 the tool with the holders and slider a, can be advanced or withdrawn by 
 working the screw e. The nuts of the screws c and h, fig. 331, are not 
 screwed fast to the sliding plates, but are held by two pins #,fig. 335, which fit 
 into grooves u, fig. 334, in each side of the nut ; by these means the sliding 
 plate can at any time be taken out by only unscrewing one of the brass slides 
 from the grooves i, without taking out the screw or nut. In order to make the 
 grooves always fit their slides, the two pieces of brass y y, fig. 331, which 
 compose the sides of the groove, have elliptic holes for their screws v, so as 
 to admit, w'hen the screws are slackened, of being pushed inw'ards by the 
 screw w which works in a lump of metal cast with the part A A. 
 
 The large lathes which Mi . Maudslay uses in his manu- 
 factory, instead of being worked by the foot, as represented 
 in fig. 325, are worked by hand ; the wheel and fiy-wlieel 
 which the men turn works by a strap on another wheel fixed 
 to the ceiling directly over it ; on the axis of this wheel is a 
 larger one, which turns another small wheel or pulley fixed 
 to the ceiling, directly over the mandrel of the lathe ; and 
 this last has on its axis a larger one which works the mandrel 
 D, by a band of catgut. These latter wheels are fixed in a 
 frame of cast-iron, movable on a joint ; and this frame has 
 always a strong tendency to rise up, in consequence of the 
 action of a heavy weight, the rope from which, after passing 
 over a pulley, is fastened to the frame ; this weight not only 
 operates to keep the mandrel-band tight, when applied to 
 any of the grooves therein, but always makes the strap be- 
 tween the two wheels on the ceiling fit. As it is necessary 
 that the workman should be able to stop his lathe, without 
 the men stopping who are turning the great wheel, there are 
 two pulleys or rollers (on the axis of the wheel over the 
 lathe) for the strap coming from the other wheel on the ceil- 
 ing ; one of these pulleys, called the dead pulley, is fixed to 
 the axis and turns with it, and the other, which slips round it, 
 is called the live pulley ; these pulleys are put close to each 
 other, so that by slipping the strap upon the live pulley, it 
 will not turn the axis ; but if it is slipped on the other, 
 it will turn with it ; this is effected by a horizontal bar, with 
 two upright pins in it, between which the strap passes. This 
 bar is moved in such a direction as will throw the strap into 
 the live pulley, by means of a strong bell- spring; and in is 
 
THJi OPBRATIVE MliClIANIC 
 
 326 
 
 contrary direction it is moved by a cord fastened to it^ which 
 passes over a pulley, and hangs down within reach of the 
 workman’s hand ; to this cord is fastened a weight heavy 
 enough to counteract the bell-spring, and bring the strap 
 upon the dead pulley to turn the lathe ; but when the weight 
 is laid upon a little shelf, prepared for the purpose, the spring 
 will act and stop it. 
 
 Mr. Maudslay has likewise some additional apparatus for 
 cutting the teeth of wheels, in which the face of the mandrel 
 D, fig. 325, has seventeen concentric circles upon it, each 
 divided into a different number of equal parts, by small holes. 
 
 There is a thin stop x, fig. 325, which moves round on a screw fixed 
 in the standard F ; this stop is made of thin steel, and is so fixed, that 
 when it is turned up, and its point inserted into any of the divisions 
 of the mandrel, it will have a sufficient spring to keep it there; the 
 wheel to be cut is fastened, by means of a chuck, to the screw n, and after 
 it has been turned, and brought to the proper shape,, the rest, J, is to be 
 taken away, and the slide-tool substituted ; a square bar is then put into 
 the two holders b b, fig. 331 ; this bar has two branches for holding the ends 
 of a spindle, near one end of which is a pulley, and at the other are four 
 chisels fixed perpendicularly into the spindle for cutting out the teeth, (in- 
 stead of the circular saw commonly used ;) the pulley is turned (with the inter- 
 vention of several wheels to augment the velocity) by the- same great wheel 
 as the lathe, with 7300 revolutions per minute ; the mandrel is then fixed by 
 the stop X, fig. 325, and the cutter advanced towards the wheel, by the 
 screw c, fig. 331. When it has cut that tooth, the cutter is withdrawn, and 
 the mandrel turned to another division, and a tooth is cut again as before. 
 At that part of the frame of the cutting-spindle where the bar which is fixed 
 in the holders of the slide-tool connects with the two branches, there is a 
 joint, by which the cutting-spindle can be set in an inclining position for 
 cutting oblique teeth, like those which are to work with an endless-screw. 
 The great velocity with which this spindle turns soon generates by friction 
 and resistance a degree of heat sufficient to expand it very sensibly ; but this 
 ingenious mechanist, foreseeing such a circumstance, has judiciously com- 
 pensated for it in his construction, by making the spindle so short as to 
 play loosely in its sockets at the commencement of the motion; but after a 
 few seconds the expansion is such as to cause the whole to fit together as it 
 ought to do, and the work of cutting to proceed with accuracy and safety, 
 
 Mr. Smart, of the Ordnance-wharf, Westminster, has 
 made some very useful improvements in the art of turning, 
 and particularly has struck out a simple method of turning 
 cylinders and cones in wood. 
 
 Ilis turning machine is illustrated in figs. 339 and 340, where the legs or 
 stiles L, the puppets A B, the cheeks o o, the pikes and screws M, N, R, 
 with the handle D, are but slightly varied from the usual construction, 
 Round the mandrel E passes a band F F, which also encompasses a large 
 wheel, not shown in the figure ; and when this large wheel is turned round 
 with moderate swiftness, it communicates a rapid velocity to the mandrel E, 
 and the long piece of wood G, which is proposed to be made cylindrical. 
 This piece is previously hewn into an octagonal form. The cutting frame H 
 t^ontaim a sharp iron tooj, which is to answ'er the purpose of the common 
 
AND MACHINIST. 
 
 327 
 
 iurning gnuge, and which is fitted into the frame so as to project a little be- 
 yond its inner part, after the manner of a carpenter’s plane-iron for round or 
 ogee work. Then, while the piece G is turning swiftly round by a man 
 working at the great wheel, another man pushes the frame H gently oii 
 from L towards M, the lower part of that frame fitting between the cheeks 
 o 0, and sliding along between them. By this process, the piece G is re- 
 duced to a cylinder, moderately smooth ; and, in order to render the smooth- 
 ness as complete as need be, a second cutter, and its frame I, adapted to a 
 rather smaller cylinder than the former, is pushed along in like manner 
 from L to M. This operation may be performed with such speed, that a 
 very accurate cylinder of six feet long, and four inches diameter, may be 
 fixed to the lathe and turned in much less than a minute. 
 
 Mr. Smart turns a conical end to one of these cylinders with 
 great facility, by means of a cutting-blade fixed in an iron hol- 
 low conical frame K, the smaller end of which admits the 
 pike from the screw S, fig. 340, to which one end of the cy- 
 linder G is attached ; as the cylinder turns rapidly round, the 
 cutter K is conducted gently along it by means of the hollow 
 frame, and soon gives the conical shape to the end of tlie 
 cylinder, as required. 
 
 Some important directions for tuz’inng screws, ovals, cubes, 
 rose-work^ swath- work, &c. may be seen in Moxon^ s Mechanic 
 Exercises: see also, Tour pour faire sans Arbre toutes 
 Sortes de Vis,’’ par M. Grandjeau, in “ Recueil des Machines 
 et Inventions approuvdes ^iar I Acad. Hoy. des Sciences/* 
 tom. V. ; and Mr^ Healy’s method of cutting screws in the 
 common turning-lathe. 
 
 Previously to entering upon the several branches of our 
 manufactures, where machinery will be found in its most 
 jcomplex state, it may, perhaps, be considered not alto- 
 gether irrelevant, if wc take a cursory view of the manner in 
 which we have conducted the reader thus far. In the first 
 place, we have taken up the subject by treating of the Me- 
 chanical Powers, and the attributes of matter, as if he were 
 totally unacquainted with the science ; and having given him 
 every necessary information with respect to the fundamental 
 principles, have then proceeded to demonstrate the Moving 
 Powers ; thus progressively leading him on to a perfect com- 
 prehension of the invariable laws of mechanics, before we have 
 ventured to introduce to his notice certain simple machines 
 acting, either separately or conjointly, as accessors to our 
 manufactures. These we have now also portrayed, and so 
 amply, that we feel satisfied he will, though totally destitute 
 of the science at the commencement, be able fully to compre- 
 hend and appreciate the several excellencies of the various 
 combinations which will now be unfolded to him. 
 
THE orfiRA'IIVE MECHAM6 
 
 328 
 
 IRON MANUFACTURE. 
 
 Works for the manufacture of iron, owing to the great 
 sums necessary to be expended in their erection, have, till 
 ^vithin these few years, been confined to a very limited scale ; 
 hut the spirit of enterprise which has of late, and more 
 especially since the French revolution, manifested itself in 
 nearly the whole of our manufiictures, conjoined to the im- 
 mense capitals acquired by many individuals, and the difficulty 
 of employing them to a better advantage, have given to the 
 manufacture of this highly valuable metal a more decisive 
 character. 
 
 The ores from which the metal is extracted are, in this 
 country, found, in general, to consist of iron united with 
 oxygen and various proportioiis of earthy matter. 
 
 The earthy matter in a state of combination with the iron may 
 be divided into two classes ; the one called argillaceous, from 
 abounding in excess of alumine, or clay ; the other calcareous, 
 from abounding in lime. The former is by far the most 
 common ; indeed it is owing to the f)i*e being so frequently 
 met With in an argillaceous state, that iron-masters are so 
 very inattentive to its quality, and that we sometimes see 
 them use limestone as a flux when the ore already abounds 
 with calcareous ingredients. 
 
 Both lime and clay, when separately subjected to the usual 
 heat of the blast-furnace, are infusible ; but on being mixed 
 together in certain proportions, are too fusible even for the 
 common purposes of brick-making. An alloy of two metals 
 is also fusible at a temperature much less than the arith- 
 metical mean of the metals themselves. 
 
 Such being the case, it is much to be regretted, that iron- 
 masters, in general, are so very ignorant of, and inattentive 
 to, the fusibility of the diflerent combinations of the iron ores, 
 which causes them so frequently to be at a loss what to add 
 to the furnace in order to produce the most fusible cinder. 
 An analysis of the ore, by which they might learn the relative 
 proportions of its earthy constituents, and the quantity of 
 limestone or clay to be added as a flux, would, in the end, 
 prove much to their advantage. 
 
 In the usual process of smelting, the coke is always a fixed 
 quantity, and the proportions of ore and limestone ;ire 
 varied according to the quantity of iron to be made, and the 
 
AND MACHINIST, 
 
 329 
 
 TTorking order of the furnace. In proportion to the quantity 
 of lime and ore that is added to the standard quantity of the 
 coke, the furnace is said to carry a greater or less burthen. 
 Some furnaces carry so little burthen as not to produce more 
 than 13 or 14 tons per week; whilst others, with the same 
 sized furnace, will yield 60 and even 70 tons in an equal time. 
 The burthen of the last-mentioned furnaces is very great, the 
 ore to the coke being, in some cases, as 13 to 7- The quality 
 of the iron is uniformly inferior. 
 
 The burthen of the furnace will vary according as the iro?i 
 to be made is required to possess more or less carbon ; for 
 instance, in making No. 1, or the best iron, which contains 
 the greatest portion of carbon, the burthen must be consider- 
 ably less than that required to make less carburetted iron, or 
 what is called white- iron, or forge-pig. 
 
 To afford a general idea of the proportions of the materials, 
 we shall state the quantities, given by Mr. Mushett, tis used 
 at a blast-furnace, making good melting iron, which is of an 
 intermediate quality between No. 1 and the forge-pig. The 
 ore is argillaceous, containing on the average about 27 per 
 cent, of iron ; the coal rather soft, but not very bituminous, 
 and contains a large proportion of carbonaceous matter ; and 
 the limestone, which is that abounding in shells, from Critch, 
 in Derbyshire, is very good. It works with a bright tuyere, 
 and receives from the blast about 2,500 cubic feet in a 
 minute, through a circular aperture of 2| inches in diameter. 
 
 It is usual at this, and most other furnaces, to divide the 
 men into two classes, one class to relieve the other every 
 12 hours ; these periods are called shifts. The average 
 charges of coke per shift are 50 (each 2^ c\vt.) or about 
 six tons. The quantity of calcined ore for the manufacture 
 of good melting iron is upon a par with the coke ; and for 
 forge-pig, or the least carburetted variety, six of coke to 
 seven of ore. The limestone unburnt, under the same 
 circumstances, is to coke as 4 to 11 ; and for melting 
 metal, retains a similar ratio. With the above charge per 
 day, that is, for twelve hours, this furnace makes on the 
 average about 40 tons melting iron per week. 
 
 After the ore is dug, it is drawn from the pit by the power 
 of steam-engines ; it is then, in order to extract the arsenic 
 and sulphur, subjected to a process called roasting. This 
 process consists in laying the ironstone in strata with refuse 
 pit-coal, called in Staffordshire slack, and setting fire to it on 
 the windward side, burning it in large heaps in the open air. 
 
 When the ore has been roasted, it is taken to the smelting 
 
330 
 
 THK OPERATIVE MECHANIC 
 
 or blast furnace, the lower part of which is filled with either 
 charcoal or coke ; the coke is always a fixed quantity, and 
 the proportion of limestone added to the ore is according to 
 the quantity of heterogeneous matter with which the metal is 
 combined. 
 
 A section of the blast-furnace is represented in fig 346. A, at the top 
 of the furnace, is an opening for the introduction of the materials ; B, the 
 body of the furnace ; C, the place where the blast is introduced ; and D, 
 a cavity to receive the metal when released from the earthy matter. 
 
 The materials in the furnace are, previously to the intro- 
 duction of the blast, heated simply by the draught of the 
 atmosphere ; the coke and limestone to a bright red or white 
 heat, and the iron-ore to a melting heat. 
 
 When the blast is introduced, the metal immediately above 
 it is brought into a state of fusion, and penetrates through 
 the fuel into the cavity D. The ore and fuel that were above 
 it sink down to fill up the space left by the ore melted and 
 the fuel consumed. This next comes under the operation of 
 the blast, and is similarly reduced. 
 
 The men who attend the furnace keep adding fuel, ore, and 
 limestone, through the opening A, at the top, and the 
 operation of smelting goes on, until the melted iron, in the 
 cavity D, rises nearly to a level with the tuyere-irons, or 
 blast-pipes. 
 
 The melted iron is then tapped, by driving a round-pointed 
 bar into a sort of loam, with which the hole is stopped, and 
 run into moulds made in sand 5 in this state it is called pig 
 or cast-iron. 
 
 When the slag, in smelting, has a greenish-grey appear- 
 ance, it is a certain sign that the furnace is in excellent 
 order ; and when the colour changes to black, it denotes that 
 something is going wrong. 
 
 In making the best iron, called No. 1, which possesses the 
 greatest quantity of carbon, it frequently happens that a 
 portion of the iron will unite with a great excess of carbon ; 
 and as this carburet is less fusible than the iron, it will, pre- 
 viously to the iron entering into the pig-moulds, be seen 
 floating at the top in the form of scales. The appearance of 
 this substance, called by the workmen kish, is a sign that the 
 furnace is working the best sort of iron ; indeed, it is so 
 common an attendant on the production of the most highly 
 carbonized iron, that the workmen have applied the term 
 Ms hi/ to that peculiar sort of iron. 
 
 The limestone and the earths being much lighter than the 
 metal, float upon its surface, and gradually rising as the metal 
 
AND MACHINIST. 
 
 331 
 
 accumulates, is ultimately discharged over a dam-nto7iey 
 which, though at right angles, we have represented by the 
 dotted linec enclosing the letter I. T is called the lymp- 
 stone, and forms a bridge over the cavity in which the liquid 
 cinder rises ; t is the lymp-plate, to give the stone greater 
 firmness, as e, which is called the dam-plate, does the dam- 
 stone. The cinder, if not taken to mend the roads, is thrown 
 away as useless. 
 
 Sometimes two blasts are introduced, as may be seen in fig. 347. That 
 blast, and that furnace, which can reduce the greatest quantity of fuel in a 
 certain time, will always produce the greatest quantity of iron. 
 
 The blast conveyed into the furnace is from 1,000 to 4,000 
 feet per minute ; and it is worthy of remark, that the quantity 
 of metal fused does not agree with the ratio of the blast ; for 
 instance, a blast of 1,500 feet per minute will manufacture 
 20 tons of melting iron per week ; a blast of 3,000 only 30 
 tons, and a blast of 6,000, which is double the last, and four 
 times the amount of the first blast, only 36J tons per week ; 
 and again, a blast of 2^ lbs. per square inch will manufacture 
 from 22 to 25 tons per week ; while two pipes of the same 
 diameter as the last, with a blast of 3 lbs. per square inch, 
 udll never exceed 30 tons. 
 
 In the summer months, owing to the increased temperature 
 of the atmosphere, the furnaces yield little better than one 
 half the quantity that they do in winter, and the iron is of 
 an inferior quality. In some manufactories, by adding a 
 greater quantity of fuel, the quality of the iron is preserved ; 
 but in others no addition of fuel will compensate for the 
 deficiency either in quality or quantity. 
 
 In presenting the section of a blast-furnace, represented in 
 fig, 346, we do not pretend to recommend it as the best form 
 of construction. Different iron-masters have variously con- 
 structed their furnaces, and as each of them can boast of 
 being in some degree successful, it were needless to give a 
 description of any particular one ; we shall therefore briefly 
 mention, that of whatever materials the buildings be made, 
 care should be taken that they contain no more moisture than 
 is absolutely necessary for their proper construction. 
 
 In the erection of the wall, a space of about six inches 
 should be left from the bottom to the top ; in this aperture 
 small fragments of sand-stone, not exceeding the size of an 
 egg, may be introduced, so that when the expansion, pro- 
 ceeding from the fire-building of the interior, causes the 
 bricks immediately in contact to push outwards, the masses 
 of sand-stone are instantly reduced in size, and filling the 
 
332 
 
 THE OPERATIVE MECHANIC 
 
 interstices occasioned by their former angular shape, occupy 
 much less space, and present to the flame or fire, should it 
 be inclined to penetrate so far, a solid vertical stratum of 
 sand, after having secured the expansion of the furnace to 
 the extent of some inches. The eftects of the pressure are 
 thus diverted from the shell of the building, and lost in the 
 pulverization of the sand- stone. 
 
 The advantages resulting from this plan may be nearly- 
 doubled, by using a double lining of fire-bricks, between each 
 of which and the common building a similar vacancy should be 
 left, but filled with sharp sand, containing no more moisture 
 than serves to compact it in a firm body ; as this moisture 
 becomes gradually^ expelled in the slow heating or annealing 
 of the furnace, the sand occupies less l)ulk, or, which is the 
 same in effect, is then susceptible of a greater degree of com^ 
 pression when the gradual expansion of the furnace comes 
 on. It is evident that the force is here also diverted against 
 the sand, in place of acting immediately with a tendency to 
 enlarge the circumference of the building. 
 
 Over and above tliese precautions, the annealing or drying 
 of the furnace in a progressive and regular manner ought to 
 be carefully Jittended to, and continued for two or three 
 months at least. 
 
 Many methods have been adopted to obtain a regular and 
 uniform blast. The first that we shall notice, and which is 
 in pretty general use, is, by discharging the air from the 
 blowing-cylinder into an intermediate cylinder of larger dia- 
 meter, called the regulator ; in this vessel is a loose piston, 
 which is forced up by the air from the blowing-cydinder, and 
 being weighted, it descends during the returning stroke, and 
 continues to press the air into the furnace, by which means 
 a more steady and uniform blast is kept up than would be 
 effected by the first cylinder alone. 
 
 As this method of regulating the blast has been found to 
 be far from perfect, other means have been resorted to with 
 a view of obtaining the desired end. The one called the 
 water-regulator consists of a large cistern, in which another 
 of less area and capacity is inverted. Through the bottom 
 of the smaller cylinder, which is, from its being inverted, 
 uppermost, a pipe communicates with the blowing-cylinder. 
 This inner cistern is filled with water, as is also the space 
 between the inner and outer cistern to the same level. Now, 
 supposing the air to be forced from the blowing-cylinder 
 through the above-mentioned pipe into the inner cistern, the 
 water, being displaced by the air, will descend in the inner 
 
AND MACHINIST. 
 
 S33 
 
 cistern, ami rise up l)etween the two vessels till the column 
 of w'ater on the outside be ecjiuil to the required force 
 of the blast ; this column would be about 4 lbs. upon a square 
 inch, and about nine feet. Another pipe proceeds from the 
 same cavity in the inner vessel to the furnace, and com- 
 municates nearly a uniform blast, varying only with the outer 
 cohimii of water, which will 1)e less as the outer surface of the 
 water is greater. 
 
 This contrivance, though for some time considered an 
 important discovery, has, in many instances, been abandoned, 
 owing to its carrying water, both in a state of sprayq produced 
 bv the agitation, and in a state of vapour, into the furnace, 
 by which both the quality and quantity of the iron was 
 materially affected. 
 
 Another mode has been attempted to equalize the blast, 
 called the air- vault. The first experiment of this nature was 
 tried at the Clyde iron-works, by excavating a large cavity 
 in a rock, into which the air was forced by the blowing 
 machine ; but the trial was unattended by success, partly from 
 the vault not being air-tight, and partly from the moisture 
 which exuded from the rock mixing with the air. 
 
 A more successful experiment was made at the Carron 
 iron-works. An air-vault of wrought-iron plate has been 
 employed in one of the furnaces at Bradley, in Staffordshire, 
 which appears to answer very well. Its form is a cylinder 
 about 10 or 12 feet diameter, and 50 or 60 feet long. 
 
 According to an average deduced from a series of experiments madd by 
 Mr David Mushett,* it appears, that when the outer air was from 63° to 68**, 
 the air immediately after its escape from the blowing cylinder into a 
 receiving vessel, was increased from 63° to 90°, and from 68° to 99i°. In 
 ah average of thirty experiments the air in the act of condensing was raised 
 30°. This would have the effect of increasing its volume not less than ^ 
 of the whole, and the increased pressure of the blast by this cause alone, 
 w ould be nearly half a pound upon an inch. Or, in other words, if the 
 air were introduced into the furnace at 60°, the same quantity would be 
 admitted with half a pound less pressure upon an inch than if it were 
 90°. Hence any means of cooling the air after its condensation, in all 
 seasons of the year, must be attended with beneficial consequences. If the 
 air-vault were made of WTOught-iron, and its surface constantly kept wet, 
 the evaporation from so great a surface, if freely exposed on all sides to the 
 air, would cool the air very considerably. Indeed, without the aid of the 
 moisture, the effect would he such as to recommend its adoption. It was 
 supposed, that in the summer season there would be some advantage in 
 bringing the air under ground for a considerable distance before it entered 
 the blowing machine; but the resistance arising from the friction on the 
 
 Edinburgh Encyclofadia, Dr. Brewster, 4to. 
 
334 
 
 THE OPEUATIYE MECHANIC 
 
 sides of the channels llii-ough which il must pass has been found to be an 
 obstacle that oveo’ules it. 
 
 The pig-iron which has the smallest portion of carbon is 
 the best adapted for conversion into malleable iron ; and as 
 a proof that the pig-iron has only to lose its carbon to become 
 malleable, we shall state the fact, that we have in this country, 
 at this present time, many manufactories upon a large scale, 
 for the express purpose of converting articles made of cast- 
 iron, such as nails, cutlery, &c. into iron perfectly malleable, 
 without altering in the slightest degree the figure given to 
 them in the casting. We have even seen nails made in this 
 way welded together, and when cold bent at right angles in 
 a vice. 
 
 The method of releasing the pig-iron of its carbon, or of 
 converting it into what is called wrought or malleable iron 
 is, by placing it in an open furnace, termed a refinery^ and 
 by some a run-out furnace, heated by cokes, and subjected 
 to the operation of a very powerful blast. The pig-iron is 
 laid upon the cokes, and is soon melted, leaving much of its 
 impurity behind. This is termed refining it. The metal 
 when melted is run into plates, about four inches thick, and 
 as soon as it becomes set, is thrown into water, which makes 
 it more frangible, and easier to be broken. 
 
 The refining furnace is represented in figs. 348 and 349. A is a recess, 
 or trough, made of cast metal, having a bottom of fire-stone or brick. 
 This recess is surrounded on three sides by a cavity, through which water 
 is constantly passing from the cistern C ; p p are two pipes connected 
 with the blowing machine, and entering into conical openings in the 
 refining furnace. These pipes are kept cool by water from the pipe a, 
 which runs off at the pipe b cc. B is a shallow recess, about four inches 
 deep, to receive the melted mass. 
 
 When the cake of metal is broken into lumps of a con- 
 venient size, it is taken to the puddling furnace, where it is 
 heated with coals, without the aid of an artificial blast. As 
 soon as the metal becomes heated, and begins to melt, 
 or has a frosty appearance, the furnaceman throws in a 
 small quantity of water to keep it at a proper temperature, 
 and keeps stirring and moving it about, so that the carbon 
 makes its escape. The water that is thrown in to preserve 
 the temperature also assists in some degree the decarboniza- 
 tion. The quality of iron depends much upon the attention 
 that is paid to it during this process. 
 
 When the iron is deprived of the carbon, or fusible pro- 
 perty it before possessed, the furnaceman rolls it up into 
 balls of one half or three quarters of a cwt. each. It is then 
 
MATrrFAC-TlIJIKlE 
 
 PI. 46. 
 
 * From 346 to 332 
 
 34S t 
 
'Jr- 'I ■: I : 
 
 ti'; 
 
 :'e •- 'V. 
 
 ■ 4 ^.. , . , r; 
 
 , .' r. ■ '■‘Hii . 
 
 • !'kI 
 
 -.'■ r'- i>: 
 
 ' : ,r ' V 
 
 - ' ■"•' feg 
 
 -•' -l.- -4. %“'*?••.'??•••■•' 
 
 Ate'jf'-. 
 
 '■' ' •■' ' '■■■■'' " ■ ri^'-r'Lr:; .ft ^ 
 
 • ' ^ ' >■ ^ . .{ii 4 
 
 . Ji 
 
AND MACHINIST, 
 
 335 
 
 brought out of the furnace and placed under a tilt-hammer, 
 or passed through the rolls, or rollers, which consolidates it, 
 and forces out more of the impure parts. A considerable 
 doss in weight is sustained in this process, not only from the 
 iron losing its impurities, but also from the surface of the 
 bloom or bar oxydizing and falling off in scales whilst being 
 worked. The loss which is thus sustained in weight is 
 generally estimated at one-sixth or one-seventh of the whole. 
 
 A section and elevation of the puddling furnace is represented in fig. 350. 
 A is the door for the admission of metal, having a small square hole A, for 
 the introduction of the rake and other tools used by the furnaceman. B is 
 the chimney ; C the ash-pit ; and D the grate. At E is a circular cavity, 
 where the prepared ■ metal is laid, and the flame passes over it up the 
 chimney B. The heat of the furnace is so intense that without having the 
 door for a guard, and the small hole h for the introduction of the imple- 
 ments, the furnaceman could not approach it ; nor indeed can he as it is 
 without suffering great inconvenience. The hole is also of use for him to 
 look into the furnace to observe how the work is going on. At first the 
 light is too intense to be borne, but by practice the eye at length becomes 
 accustomed to it, and is able perfectly to distinguish the different masses as 
 they lay in the furnace. 
 
 The iron having undergone this process is taken to the 
 shears and cut into lengths of about one or two feet, and in 
 order to impart closeness and solidity is piled into pieces of 
 seven or eight together, and heated in another furnace, very 
 similar to the one just described. There is no occasion this 
 time to remove them about, for the iron having lost its 
 carbon is infusible. When it is of a sufficient heat, which 
 the furnaceman from practice can easily tell by his eye, it is 
 again brought to either the hammer or the rollers, and is 
 worked into a bar. This is called No. 2 iron. Again, further 
 to improve the quality, it is cut up, piled, and worked over 
 again; and is then called No. 3, or best iron. The more the 
 iron is worked the purer it becomes, and the grain becomes 
 more closely united ; but of course it becomes more expensive. 
 
 Two kinds of hammer, moved by machinery, are used in iron-works. 
 Tne one called the forge-hammer is represented in fig. 353. The first 
 mover gives motion to the shaft A A, by means of a cog-wheel acting upon 
 the pinion B. The shaft is regulated by a fly-wheel C, and has at the 
 further end a number of cogs, \^icb by passing under the shaft, or helve, D, 
 lift the hammer E. F is a strong horizontal beam, inserted in the post G, 
 and loaded with heavy pieces of metal, at H, to prevent it receiving motion 
 from the hammer. Another large beam of wood, made of either oak, or 
 ash, but most frequently the latter, is inserted in the posts IK. The 
 hammer in its ascent strikes against this beam, called the rabbit, wKich 
 by its elasticity reacts upon the hammer, and causes it to descend with 
 greater velocity than would be produced by gravity alone. 
 
 The construction of a tilt-hammer differs from that of the 
 
THK OPER\TlVI2 MEC HANIC 
 
 f<-)ri»;e, by being poised on a centre of motion, about the middle^ 
 or two-thirds of the length of the lielve from the hecid, and 
 from receiving its motion from cogs acting upon the tail of 
 the helve, in some few cases the ash spring is placed over 
 the head of the hammer similarly to that above described ; 
 but, in general, the tail of the helve is made to strike against 
 a fixed floor, and the hammer from the force it has received 
 continuing to rise after the tail strikes the floor, the halve 
 bends, and hy its elasticity causes the hammer to descend 
 ^vith greater force upon the anvil. 
 
 The tilt-hammer is represented in fig. 354. It is taken from a tilt-mill 
 made at the Carron iron-works in Scotland, after designs of the celebrated 
 Mr. Smeaton. It is adapted for forging iron into bars. The description 
 13 extracted from Dr. Rees’s Cyclopcedia. 
 
 Having described the manner in which the tilt-hammer is connected 
 with the first-mover, (drawings of which may be seen in the work,) the 
 author proceeds to explain the figure above referred to ; e the iron head of 
 the hammer, f its centre of motion, and d the tail or extreme end, upon 
 which the cogs of the wheel act, and which is plated with iron on the upper 
 side, to prevent it from wearing. 
 
 P is the anvil-block, which must be placed on a very firm foundation, to 
 resist the incessant shocks to which it is subjected: the centre,/, or axis 
 of the hammer, is supported in a cast-iron frame gh^ called the hirst. 
 When the cogs of the wheel strike the tail of the hammer suddenly down, 
 and raise the head, the lower side of the tail of the hammer strikes upon a 
 support n, which acts to stop the ascent of the head of the hammer e, when 
 it arrives at the desired height ; but as the hammer is thrown up with a 
 considerable velocity as well as force, the effort of the head to continue its 
 motion, after the tail strikes the stop n, aqts to bend the helve L of the 
 hammer, and the elasticity of the helve recoils the hammer down upon the 
 anvil with a redoubled force and velocity to that which it would acquire 
 from the action of gravity alone. 
 
 To obtain this action of recoil, the hirst g h must be held down as firmly 
 as possible ; and for this purpose, four strong iron bolts are carried down 
 from the four angles of the bottom plate h, and made fast to the solid basis 
 of stone R R, upon which the whole rests ; upon this basis are placed four 
 layers of timber, ikhn, which are laid one upon another, and the timbers 
 of each layer are laid cross-ways over the others. Each layer consists of 
 several pieces laid side by side, and they are slightly treenailed together, to 
 form a platform. Each platform is rather less than that upon which it rests, 
 so as to form a pillar of solid timber; on the top of which the hirst-frame, 
 g h, is placed, and firmly held down by the four bolts, which descend through 
 all the platforms, and have secure fastenings in the solid masonry beneath. 
 
 The stop n is supported by a similar pillar, but smaller, and composed of 
 three layers : the upper piece n, which is seen cross-v.mys, is about three 
 feet long, and the under side is hollowed, so that the piece bears only upon 
 the two ends, leaving a vacancy beneath it, which occasions it to bend or 
 spring every time the tail d of the hammer strikes upon it, and this aids the 
 recoiling action very much. 
 
 Tlie axis on which the hammer moves is formed by a ring of cast-iron, 
 through which the helve of the hammer is put, and held fast by wedging 
 round it. The ring has a projecting trunnion on each side, ending in an 
 

 356 
 
 I ‘ 
 
 IfliON ^ 5TEJEJL MAI^I^iPArTlITiRB 
 
 From 353 to 356 
 
 354 
 
 355 
 
 2Teele is SfockUy sr 35i Strand 
 

AND MACHINIST, 
 
 337 
 
 obtuse conical point, which is received in a socket firmly fixed in the hirst- 
 frame g h, by screws and wedges, one of which is seen at r. These two 
 sockets are thus capable of adjustment, so as to make the hammer face fall 
 flat upon the anvil. 
 
 In the Carron iron-works, three hammers are worked from the same 
 shaft. In such case it is necessary to have the three wheels ihat com- 
 municate motion to their respective hammers of different sizes and numbers 
 of cogs to produce that velocity in each hammer which is best adapted for 
 the work it is to perform ; thus the wheel for the hammer, which is repre- 
 sented in fig. 352, has eight cogs, and therefore produces eight blows of the 
 hammer for each revolution of the fly-wheel; the wheel for the middle 
 hammer has 12 cogs; and the wheel for the smaller hammer 16; the 
 latter will therefore make two strokes for every one of the great hammers. 
 In fixing the three wheels upon the great shaft, care is taken that they 
 shall produce the blows of the different hammers in regular succession, 
 and equalize as much as possible the force which the water-wheel must 
 exert. Tire wheels are fixed on the shaft by means of a wedging of hard 
 wood, driven in all round; the wood being capable of yielding a little to 
 the shocks occasioned by the cogs meeting the tails of the hammers, 
 renders the concussions less violent. 
 
 The following are the principal dimensions : 
 
 The head of the great hammer weighs cwt. and it is intended to make 
 150 blows per minute ; it is lifted 17 inches from the anvil at every blow. 
 
 The middle hammer is 2 cwt. and makes 225 blows per minute ; it is 
 lifted 14 inches each time. 
 
 The small hammer weighs 1^ cwt* and makes 300 blows per minute ; it 
 is lifted only 12 inches. 
 
 To produce these velocities, the great axis upon which the cog-wheels 
 are fixed must make 18| turns per minute; and the pinion upon this axis 
 being in proportion with the cog-wheel upon the shaft of the water-wheel 
 as 1 is to 3, the water-wheel must make 6^ revolutions per minute ; the 
 water-wheel being 18 feet diameter, its circumference will be 18 x 3 . 1416 
 = 56 . 54, or 56i feet; this multiplied by 6*25 is about 353 feet motion 
 per minute, or divided by 60 = 5*9 feet motion per second for the circum- 
 ference of the water-wheel. 
 
 The tilt-mills employed in the manufacture of steel, do 
 not have the great hammer, but the largest they use is about 
 the size of the middle one, and is adapted for welding faggots 
 of steel to make sheer steel : the other two hammers are 
 about the size of the smallest just described, and are made 
 to work much quicker, viz. from 350 to 400 blows per 
 minute. This is very easily accomplished by making the 
 pinion upon the fly-wheel shaft in proportion to the cog- 
 wheel that acts upon it, and is fixed to the water-wheel, as 
 1 is to 4. 
 
 This highly raluable metal, having undergone these pro- 
 cesses, is now sold, and is used by smiths for an innumerable 
 variety of purposes. Indeed^ when we reflect upon the many 
 thousands of men, women, and children, who are daily em- 
 ployed in the manufacture and w'orking of this metal ; when 
 
 z 
 
338 
 
 THli OPIiRATIVE MECHANIC 
 
 we consider the immense number of families of miners, 
 melters, refiners, smiths, and other handicraftsmen, who, in 
 ail the civilized parts of the world, look up to this particular 
 branch of manufacture for their maintenance and support ; 
 when we consider, that the once obscure and inconsiderable 
 village of Merthyr T}"dvil, though wild, barren, and sterile, 
 and too poor to produce even the common necessaries of life, 
 lias been peopled in the teeth of every obstacle, and, within 
 the space of seventy years, has, through the manufacture of 
 this metal, become by far the largest and most populous 
 town in Wales; we cannot but rejoice that this metal is one 
 of the staple manufactures of Great Britain. 
 
 When this metal has become too much worn to answer 
 longer the purpose for which the Smith designed it, it is sold 
 to the ^dealers in marine stores,’ who assort it into three 
 parcels; one called coach-tyre^ consisting of the old tyre of 
 coach and other wheels ; another bushel iron, being remnants 
 of old hoops, and different pieces of iron of similar nature ; 
 and another scrap or nut-iron, consisting of old nails, screws, 
 nuts, and pieces of that description. 
 
 These are sold to the manufacturer to be remanufactured. 
 The process of remanufacturing is as follows : 
 
 Two pieces of iron, each forming three sides of a square, 
 are fixed to a wooden bench, about 10 or 12 inches apart. 
 In the space between these two pieces are placed two rods of 
 iron, about three-eighths of an inch square, one rod being 
 placed close to each of the pieces. On these rods are laid 
 pieces of old hoop, previously straightened, and cut to the 
 proper lengths of 12 or 14 inches, according to the intended 
 length of the faggot. The ends of the hoop rest upon the 
 bottom of each of the pieces of iron first described, and similar 
 pieces of hoop are ranged upon each side, while the interior 
 is filled with bushel or scrap iron. The top is then covered 
 with hoop, and the whole pressed tightly down, and bound, 
 by bringing the ends of the three-eighths rod together, and 
 screwing them round. This is termed a faggot, being about 
 12 or 14 inches long, and six inches square. 
 
 The faggot is then carried to a furnace not much unlike 
 the puddling furnace, and w’hen sufficiently heated is brought 
 out, and passed through the rollers, and made into what are 
 called- These blooms are generally about two feet 
 
 long, by three or four inches wdde, and two thick. 
 
 The blooms are again exposed to the heat in the furnace, 
 and when at a proper temperature are taken cut and passed 
 through the rollers, either those represented in fig. 351, or 
 
AND MACHINIST. ' 
 
 339 
 
 those in fig. 352, accordingly as they are to be made into 
 hoops, or bars. The hoop-rollers are represented in fig. 351 ; 
 the bar-rollers in fig. 352. 
 
 Tables of the average weight of bars, squares, and bolts, 
 10 feet in length. 
 
 BARS. 
 
 Inches. 
 
 c. 
 
 qr 
 
 lb. 
 
 Inches. 
 
 c. 
 
 qr, 
 
 , lb. 
 
 Inches. 
 
 C. 
 
 qr, 
 
 , lb. 
 
 6 X 
 
 3 
 
 T 
 
 1 
 
 1 
 
 15 
 
 3|- X 
 
 3 
 
 T 
 
 — 
 
 3 
 
 12 
 
 2J X 
 
 — 
 
 1 
 
 23 
 
 
 5 
 
 ■S' 
 
 1 
 
 0 
 
 13 
 
 
 -5* 
 
 — 
 
 2 
 
 24 
 
 4 
 
 — 
 
 1 
 
 10 
 
 
 i- 
 
 — 
 
 3 
 
 19 
 
 
 4 
 
 — 
 
 2 
 
 8 
 
 3 
 
 ■F 
 
 — 
 
 1 
 
 1 
 
 X 
 
 3 
 
 T 
 
 1 
 
 1 
 
 1 
 
 
 3 
 
 ■S' 
 
 — 
 
 1 
 
 20 
 
 2‘- X i 
 
 — 
 
 2 
 
 2 
 
 
 4 
 
 1 
 
 0 
 
 6 
 
 3^ X 
 
 3 
 
 •5' 
 
 — 
 
 3 
 
 5 
 
 s 
 
 F 
 
 — 
 
 1 
 
 18 
 
 
 4 
 
 — 
 
 3 
 
 10 
 
 
 5 
 
 •S' 
 
 — 
 
 2 
 
 18 
 
 tV 
 
 — 
 
 1 
 
 14 
 
 5 X 
 
 3 
 
 1 
 
 0 
 
 13 
 
 
 4 
 
 — 
 
 2 
 
 4 
 
 4 
 
 — 
 
 1 
 
 9 
 
 
 5 
 
 ■S' 
 
 — 
 
 3 
 
 23 
 
 
 3 
 
 •S' 
 
 
 1 
 
 16 
 
 3 
 
 F 
 
 — 
 
 1 
 
 0 
 
 
 4 
 
 ; 
 
 3 
 
 2 
 
 3J X 
 
 3 
 
 T 
 
 — 
 
 2 
 
 27 
 
 2x4- 
 
 — 
 
 1 
 
 24 
 
 4| X 
 
 3 
 
 1 
 
 0 
 
 10 
 
 
 S 
 
 — 
 
 2 
 
 14 
 
 5 
 
 F 
 
 — 
 
 1 
 
 15 
 
 
 5 
 
 •S' 
 
 — 
 
 3 
 
 19 
 
 
 4 
 
 ■ — 
 
 1 
 
 27 
 
 tV 
 
 — 
 
 1 
 
 11 
 
 
 4 
 
 — 
 
 2 
 
 25 
 
 
 3 
 
 •ff 
 
 — 
 
 1 
 
 14 
 
 4 
 
 — 
 
 1 
 
 6 
 
 X 
 
 3 
 
 ■g- 
 
 — 
 
 2 
 
 5 
 
 3 X 
 
 3 
 
 T 
 
 — 
 
 2 
 
 22 
 
 3 
 
 F 
 
 — 
 
 0 
 
 26 
 
 3 
 
 T 
 
 1 
 
 0 
 
 4 
 
 
 4 
 
 — 
 
 2 
 
 8 
 
 1-g- X -|- 
 
 — 
 
 1 
 
 20 
 
 
 .4 
 
 — 
 
 3 
 
 13 
 
 
 4 
 
 — 
 
 1 
 
 23 
 
 F 
 
 — 
 
 1 
 
 12 
 
 
 ■r 
 
 — 
 
 
 21 
 
 
 3 
 
 •F 
 
 — 
 
 1 
 
 10 
 
 9 
 
 r*T 
 
 — 
 
 1 
 
 9 
 
 
 3 
 
 s 
 
 — 
 
 2 
 
 11 
 
 2| X 
 
 3 
 
 T 
 
 — 
 
 2 
 
 14 
 
 4 
 
 — 
 
 1 
 
 5 
 
 X 
 
 T 
 
 — 
 
 3 
 
 25 
 
 
 5 
 
 F 
 
 — 
 
 2 
 
 2 
 
 3 
 
 •ff 
 
 — 
 
 0 
 
 24 
 
 & 
 
 — 
 
 3 
 
 7 
 
 
 
 — 
 
 1 
 
 20 
 
 If X f 
 
 — 
 
 1 
 
 17 
 
 
 4 
 
 — 
 
 2 
 
 17 
 
 
 3 
 
 ■S' 
 
 — 
 
 1 
 
 7 
 
 5 
 
 F 
 
 — 
 
 1 
 
 10 
 
 
 3 
 
 ■g- 
 
 — 
 
 2 
 
 0 
 
 2i X 
 
 •T 
 
 — 
 
 2 
 
 8 
 
 9 
 
 TF 
 
 — 
 
 1 
 
 5 
 
 4 X 
 
 3 
 
 — 
 
 3 
 
 19 
 
 
 s 
 
 ■F 
 
 — 
 
 1 
 
 25 
 
 
 — 
 
 1 
 
 2 
 
 
 4 
 
 — 
 
 3 
 
 1 
 
 
 4 
 
 — 
 
 1 
 
 15 
 
 3 
 
 F 
 
 — 
 
 0 
 
 23 
 
 
 4 
 
 — 
 
 2 
 
 12 • 
 
 
 3 
 
 "S’ 
 
 — 
 
 1 
 
 4 
 
 1^" X -r 
 
 — 
 
 1 
 
 11 
 
 
 3 
 
 ■S' 
 
 — 
 
 1 
 
 24 
 
 X 
 
 3 
 
 — , 
 
 2 
 
 5 
 
 s 
 
 F 
 
 — 
 
 1 
 
 3 
 
 
 
 
 
 
 
 
 
 
 9 
 
 tf 
 
 — 
 
 1 
 
 0 
 
 z2 
 
340 
 
 THE OPERATIVE MECHANIC 
 
 SQUARES. 
 
 1 BOLTS. 
 
 Inches. 
 
 C. qr 
 
 .lb. 
 
 Inches. 
 
 C. qr 
 
 . lb. 
 
 3 
 
 2 
 
 3 
 
 0 
 
 3 
 
 2 
 
 0 
 
 18 
 
 
 2 
 
 2 
 
 3 1 
 
 2| 
 
 1 
 
 3 
 
 22 
 
 
 0 
 
 1 
 
 8 1 
 
 24 
 
 1 
 
 3 
 
 6 
 
 2i 
 
 2 
 
 0 
 
 11 
 
 21- 
 
 1 
 
 2 
 
 17 
 
 
 1 
 
 3 
 
 18 
 
 24 
 
 1 
 
 1 
 
 23 
 
 24 
 
 I 
 
 2 
 
 24 
 
 24 
 
 1 
 
 1 
 
 11 
 
 2^- 
 
 1 
 
 2 
 
 5 
 
 24 
 
 1 
 
 0 
 
 24 
 
 2^ 
 
 1 
 
 1 
 
 14 j 
 
 24 
 
 1 
 
 0 
 
 9 
 
 2 
 
 1 
 
 0 
 
 25 ! 
 
 2 
 
 — 
 
 3 
 
 24 
 
 14 
 
 1 
 
 0 
 
 8 
 
 14 
 
 — 
 
 3 
 
 9 
 
 14 
 
 — 
 
 3 
 
 21 
 
 14 
 
 — 
 
 2 
 
 26 
 
 14 
 
 — 
 
 3 
 
 2 
 
 14 
 
 — 
 
 2 
 
 16 
 
 14 , > 
 
 — 
 
 2 
 
 21 
 
 14 
 
 — 
 
 2 
 
 3 
 
 u 
 
 — 
 
 2 
 
 11 
 
 14 
 
 — 
 
 1 
 
 24 
 
 14 
 
 — 
 
 1 
 
 25 
 
 14 
 
 — 
 
 1 
 
 14 
 
 I 4 
 
 — 
 
 1 
 
 15 
 
 14 
 
 — 
 
 1 
 
 5 
 
 1 
 
 — • 
 
 1 
 
 6 
 
 1 
 
 — 
 
 0 
 
 27 
 
 7 
 
 — 
 
 0 
 
 26 
 
 7 
 
 ■Hr 
 
 — 
 
 0 
 
 20 
 
 3 
 
 T 
 
 — 
 
 0 
 
 19 
 
 3 
 
 T 
 
 — 
 
 0 
 
 15 
 
 s 
 
 K 
 
 — 
 
 0 
 
 13 
 
 5 
 
 TT 
 
 — 
 
 0 
 
 10 
 
 4 
 
 — 
 
 0 
 
 8 
 
 4 
 
 — 
 
 0 
 
 17 
 
 STEEL MANUFACTURE. 
 
 When iron has lost all its carbon, and has become malle- 
 able, it can be reimpregnated with carbon, to a certain extent^ 
 without materially injuring its malleable properties. 
 
 The compound of iron and carbon thus produced is called 
 steel. 
 
 To reimpregnate the iron with carbon, it must be put into 
 a close vessel, called a cementing pot, and stratified with 
 powdered charcoal. 
 
 The pots are made with a peculiar kind of stone, termed 
 firestone, which is found abundantly in the neighbourhood 
 of vSheffield. It possesses the properties of not being liable 
 to crack by the heat, or of entering into fusion. These pots 
 in the interior dimensions are from 10 to 15 feet long, and 
 from 24 to 30 inches square. Each bar of iron is com- 
 pletely covered with powdered charcoal, and the last stratum 
 oi it is usually made much thicker than the rest, and kept 
 
AND MACHINIST. 
 
 341 
 
 close with a mixture of sand and clay, to prevent the charcoal 
 from entering into combustion with the outer air. Two of 
 these pots only are contained in a furnace at a time, and fire is 
 gradually employed till the heat is little short of what would 
 be required to fuse the steel. 
 
 A vertical section, and horizontal plan, of t’ne converting furnace is 
 shown in figs. 355 and 356. In both figures the same letters denote the 
 same parts. 
 
 C C is the external cone, built in a substantial manner of stone or brick- 
 work. Its height from the ground to its vertex, in order to procure a good 
 draught of air, should not be less than 40 or 50 feet; and to procure a still 
 stronger heat a cylindric chimney of several feet in length is most generally 
 fixed on the top of the cone. The lower part of the cone, which may be 
 made of any dimensions, is built either square or octangular. The sides 
 are earned up until they meet the cone, giving the furnace the appearance 
 of a cone cut to a square or octangular prism at its base, and exhibiting 
 the parabola where every side intersects the cone. 
 
 Inside the conical building is a smaller furnace, called the vanity built of 
 fire-brick or stone, which will withstand the action of the most intense 
 heat. D D, in the section, is the dome of the vault, and E E are its 
 upright sides, the space between which, and the wall of the external build- 
 ing, is filled with sand and rubbish. A B represent the two pots that 
 contain the iron to be converted into steel. The space between them is 
 about one foot m width, and the fire-grate is directly beneath it. The 
 pots are supported by a number of detached courses of fire-brick, as 
 shown at e e, in fig. 355, which leave spaces between them, called flues, to 
 conduct the flame under the pots ; in the same manner, the sides of the pots 
 are supported from the vertical walls of the vault, and from each other, by 
 a few detached stones, represented by /, placed so that they may intercept 
 as little as possible of the heat from the contents of the pots. The adjacent 
 sides of the pot are supported from one another by small piers of stone- 
 work, which are also perforated to give passage to the flame. The bottoms 
 of the pots are built of a double course of brick-work, about six inches thick ; 
 the sides nearest together are built of a single course of stone, about five 
 inches in thickness ; and the other parts of the pot are single courses about 
 three inches, the sides not requiring so much strength, because they have 
 less heat and pressure to resist 
 
 The vault has ten flues, or short chimneys, F F, rising from it, two on 
 each side, to carry off the smoke ink) the great cone, shown in fig. 356, 
 communicating with each side, and two at each end. In the front of the 
 furnace an aperture is made through the external building, and another 
 corresponding in the wall of the vault ; these openings form the door, at 
 which a man enters the vault to put in or take out the iron ; but when the 
 furnace is lighted, these doors are closed by fire-bricks luted with fire-clay. 
 Each pot has also small openings in its end, through which the ends of two 
 or three of the bars are left projecting in such a manner, that by only 
 removing one loose brick from the external building, the bars can be drawn 
 out without disturbing the process, to examine the progress of the conver- 
 sion from time to time ; these are called the tap-holes ; they should be 
 placed in the centre of the pots, that a fair and equable judgment may be 
 formed from their result of the rest of its contents. 
 
 « b, in the elevation, is the fire-grate, formed of bars laid over the ash- 
 pit T, which must have a free communication with the open air, that it 
 may convey a current of fresh air to supply the combustion. The ash-pit 
 
342 
 
 THE OPERATIVE MECHANIC 
 
 should also have steps down to it, that the attendant to the furnace may 
 get down to examine by the light, whether the fire upon the whole length 
 of the grate be equally fierce ; and if any part appear dull, he uses a long 
 iron hook to thrust up between the bars, and open a passage for the air. 
 The fire-place is open at both ends, and has no doors. The fire-grate is 
 laid nearly on a level with the floor of the warehouse, before the furnace, 
 and the fireman always keeps a heap of coals piled up before the apertures 
 at its ends, so as to close the opening. This forms a very simple and 
 effective door; and when the furnace requires a fresh supply of fuel, a 
 portion of the heap of coals is shoved in by a sort of hoe, and the heap 
 renewed, to stop any air from entering into the furnace, except that which 
 has passed upwards through the ignited fuel, and by that means contributed 
 to the combustion. 
 
 The fire-stone& composing all those parts of the furnace 
 which are exposed to the action of the heat, are first hewn 
 nearly to size, and finished by grinding two surfaces together, 
 so that they make very perfect and close joints ; when laid 
 together, they are cemented wdth well-tempered fire-clay, 
 mixed up thin wdth water. The fire-clay which answers 
 best for this purpose, is that brought from Stourbridge, in 
 Staffordshire, and is the same of which the celebrated Stour- 
 bridge crucibles are composed; but very good fire-clay for 
 the pur}X)se is procured from Birkin-lane, near Chesterfield. 
 V^^hen the furnace has been once burnt, this clay becomes 
 equally hard with the stone, and is less liable to fly or vitrify 
 in an intense heat than any other known cement. 
 
 The flame arising from the ignited fuel upon the grate 
 passes upwards between the pots, and strikes the dome of 
 the vault, from whence it is reverberated down upon the 
 pots, and ultimately escapes through the flues or chimneys 
 of the vault. By this means every part of the pot is exposed 
 to the same degree of heat, which is of great importance. 
 
 In order to ascertain when the cementation is perfect, one 
 or two of the bars, having their ends, as before described, 
 projecting from the pots, are taken out of the furnace, and 
 examined. 
 
 The blisters upon the surface of the steel, caused by the 
 carbonic oxyd,* is, in general, adopted as a criterion to 
 judge if the metal be sufficiently converted ; but this is found 
 frequently to be fallacious, and well it may, for the size of 
 the blisters depend more upon the degree of heat to wliich 
 the bar has been exposed, than to any other cause. 
 
 The time usually required for the conversion of iron into 
 steel is about seven days and nights ; and a similar number 
 
 * Carbonic oxyd is the union of the two gases which arise from the small 
 portions of carbon and oxyd of iron, of which the iron w'as possessed, au4 
 which IS dissipated by the heat of the furnace during this long process 
 
AND MACHINIST. 343 
 
 of days and nights is aliowed for the gradual cooling of the 
 furnace. 
 
 The steel when taken from the converting furnace is found 
 on its surface to be covered with blisters; and on being 
 broken is found to be full of cavities within, for this reason 
 it is called blistered steel. 
 
 To make it sound and tenacious, it is put into a furnace, 
 and moderately heated, and is then exposed to the action of 
 the tilt-hammer, which we have already described. This is 
 called slteer-steeL 
 
 The steel is made of different degrees of hardness, by 
 giving it more or less carbon, according to the different 
 degrees and duration of the heat applied. 
 
 The steel used in the manufacture of coach-springs contain 
 the smallest portion of carbon ; a somewhat greater quantity 
 is used in the different branches of cutlery, and in the make 
 of agricultural implements ; and the greatest dose of all is 
 required for files, which cannot be too hard, provided the 
 steel be sufficiently malleable to be worked. 
 
 Cast-steel, which is entirely free from the defects of 
 blistered steel, and is, in some degree, preferable to sheer- 
 steel, is made, by placing small portions of the bars of 
 blistered steel into a crucible, capable of containing about 
 30 pounds weight. 
 
 These crucibles are made of Stourbridge clay, mixed with 
 a small portion of powdered charcoal, which makes them 
 much less liable to crack in the heating or cooling. They 
 are furnished with covers, which are more fusible than the 
 body of the vessel, and, on that account, soon enter into a 
 state of partial vitrification; by which means they become 
 closely luted at the time the steel is at a temperature suffi- 
 ciently high to be destroyed by the oxygen of the atmosphere. 
 
 The fuel employed for melting steel should consist of the 
 hardest cokes, which will give a great heat for a longer con- 
 tinuance than the soft cokes. 
 
 When the metal is fused it is taken from the furnace, and 
 poured into iron-moulds, which form it into ingots of an 
 octagonal shape, about SO inches long. 
 
 These ingots, like the bars of blistered and sheer steel, 
 are again heated, and drawn into bars by the operation of 
 the tilt-mill. By means of this machinery the ingots of cast- 
 steel can be drawn into bars one-third of an inch square ; 
 and by the hands it can be drawn into rods of a much smaller 
 size. 
 
 manufacture of steel has been greatly improved within 
 
344 
 
 THE OPERATIVE MECHANIC 
 
 a short period^ and it can now be fused with so small a por- 
 tion of carbon, as will admit of its being welded either wdth 
 iron or another piece of steel. 
 
 The most singular property belonging to steel is that of its 
 hardening by being heated red-hot, and suddenly cooled; 
 and the hotter the steel be made, and the colder the fluid 
 into which it is plunged, the harder will be the steel. Water 
 is generally employed for this purpose; and spring water is 
 considered to be the best. File-makers state, that the salt 
 which is inevitable in their hardening water, makes the steel 
 harder, and they sometimes put sulphuric acid into it for the 
 same purpose. 
 
 In hardening steel in thin plates, such as saws, particularly 
 when of cast-steel, quenching in water would cause them to 
 crack, and make them so hard as not to be useful. They 
 have, in consequence, recourse to some substance which is 
 not so good a conductor of heat. Oil, with tallow and bees’ 
 wax, and resin dissolved in it, is generally employed for these 
 articles. If the steel be heated red-hot, it mostly returns to 
 its original state. This, however, is sometimes not the case 
 with thin plates of cast-steel. In giving various degrees of 
 heat from the hard state, it becomes more soft and less elastic. 
 
 In the year 1789, Mr. David Hartley took out a patent for 
 a method of tempering steel by the aid of a pyrometer, or 
 thermometer, applied near to the surface of the article, and 
 at the same time recommended the use of heated oil, in 
 which (he says) many dozens of razors or other tools might 
 be tempered at once with the utmost facility, and the various 
 degrees of heat necessary for different purposes might speedily 
 be determined by experiment. (See Nicholson’s Journal, 
 vol. i. quarto.) An improvement of this principle has been 
 since suggested by Mr. Parkes, by providing a bath of oil or 
 of some kind of fusible metal for the tempering of every 
 species of edged tool, which contrivance would, in his opinion, 
 give to this operation a greater degree of certainty, than has 
 ever been experienced by those who have conducted such 
 manufactories, 
 
 WIRE MANUFACTURE. 
 
 Wire is made of various ductile metals; but as the manu- 
 facture of the whole is very similar, we shall confine our- 
 selves principally to a description of the manufacture of iron 
 wire, which is by far the most extensive article of commerce. 
 
AND MACHINIST. 
 
 345 
 
 The process of wire-drawing consists in drawing a piece 
 of metal through a hole in a steel plate^ which forms it into 
 a regular and even thread, of great length, according to the 
 quantity of metal supplied. 
 
 The first part of the process in the manufacture of iron 
 wire is, to subject the iron to the action of a tilt-hammer till 
 it be reduced to a size that will admit of its being drawn 
 through the plate. The tilt-hammer used is similar to that 
 which we have described in the article Iron Works.” It 
 weighs about 100 pounds, and makes 130 strokes per minute. 
 A smaller tilt-hammer, weighing about 50 pounds, and 
 making 20 strokes per minute, is also used for the wire- 
 work. 
 
 To prepare the iron for the draw-plate, the workman heats 
 six or eight inches of the end of a large bar, and works it 
 under the small tilt-hammer until it is drawn out into a 
 small and regular round rod, of about six feet in length. 
 Before it has time to cool another workman straightens it, 
 and cuts off with a hammer upon an anvil the rod thus 
 formed, and puts the remainder of the bar into the forge to 
 be again healed. 
 
 In manufacturing common wire, the bars may be advan- 
 tageously run through a pair of rollers, instead of exposing 
 them to the action of the tilt-mill ; but as the iron in rolling 
 does not acquire so much tenacity as in the hammering, this 
 process should not be attempted in the manufacture of the 
 best wire. 
 
 The rod being thus prepared by one of these methods, is 
 next drawn through a hole in the draw’-plate, either by a 
 strong machine with a chain, or else by a lever-machine. 
 
 The machines used in the process of wire-drawing are, 
 first. 
 
 The common draw-bench, which consists of a stroijg plank of wood 
 fixed on legs, like a stool or bench. It is represented in fig. 357. A is 
 an axis, fixed in a horizontal position, so that it can be easily turned round 
 by means of the four levers B B, fixed like radii on the end of the axis, 
 C is a strong strap or chain, capable of being wound about tlie axis or 
 roller, and connected by means of a link with the pincers D. E is a draw- 
 plate, perforated with holes of different sizes, lodged against two stiong iron 
 pins a a, which are fixed in the bench, and left standing up perpendicularly, 
 so that the plate can rest against them. The wire is passed through the 
 <lraw-plate E, and 'is seized by the pincers D, which, by turning the arms 
 or levers B B, winds about the roller, and draws the wire through the 
 plate. 
 
 Fig. 358 represents another kind of draw-bench, where a rack and pinion 
 are used, instead of a roller and strap or chain, as above-mentioned. If 
 idiis machine be turned by a winch the motion is more uniform, which is 
 
346 
 
 THE OPERATIVE MECHANIC 
 
 of importance for some purposes. For instance, if a piece of metal be 
 drawn rapidly through the draw-plate, it will in passing through be greatly 
 compressed, and on emerging will expand a little ; but if it be drawn 
 through the plate slowly, it will lose its expansive property. Now in the 
 common draw-bench, or one we first described, the motion communicated by 
 means of the arms B B is very irregular, and the wire is consequently some- 
 times drawn through the plate with a fast, and sometimes with a slow mo- 
 tion, wliich causes it to be of different degrees of quality ; but in using the 
 rack and pinion, by means of a winch, the motion is regular, and the 
 quality uniform. 
 
 In I>ance the roller or windlass is not employed, but tlie pincers are at- 
 tached to a lever, which alternately draws them backwards and forwards by 
 the power of the water-wheel. 
 
 The pincers are so constructed, that they open and release themselves 
 from the wire when they move towards the draw-plate ; but when drawn 
 from the draw-plate close and bite the wire with a force that will draw it 
 tl) rough the plate. 
 
 A machine of this kind is represented in fig. 359. A B is a wooden lever, 
 which moves round an iron bolt or pin p, as a centre of motion ; C is an 
 iron link, connected with the upright part of the lever A B, and having its 
 lower end formed like a ring to seize the ends of tlie pincers. The pincers 
 are supported upon an inclined plate of iron ?, which has a groove to receive 
 the head of the pincers, to direct tlrem in their motion to and from the 
 draw-plate. 
 
 The end B of the lever is depressed by cogs, affixed to the axis of the water- 
 wheel, which draws the wire througli the plate ; but when the cogs quit the 
 end of the lever, it is returned to its former position, by means of a rope 
 fastened to the end of B, and to a strong wooden pole, fixed to the top of 
 the roof of the building, which acts as a spring. As the lever returns to its 
 place, the pincers, by their own weight, slide down the inclined plane, and 
 in their descent open sufficiently to allow the wire to slide through them, 
 without extricating itself from their jaws ; and on the next descent of the 
 lever, they close upon tlie wire, and draw another portion through the plate. 
 
 Three of these machines^ of different sizes, are, in general, 
 employed in a wire-mill ; the largest draw's two inches of 
 the wire at each stroke, and makes about forty-eight strokes 
 per minute; the next four inches ; and the third five inches. 
 This last makes about sixty-four strokes per minute. This 
 mode of drawing wire is very simple, but defective ; for 
 much time is lost in the returning of the pincers ; they some- 
 times fail to take hold; and wdierever they bite they make 
 deep marks upon the wire, which are not more than two inches 
 apart in the great wire, and five inches in the smaller. 
 
 Fine wore is always made from the large wire, by reducing 
 it and lengthening it out by repeated drawings. The large 
 wire is usually manufactured at the wire-mills in the country, 
 and sometimes is reduced to small wire at the same establish- 
 ments, but those w'ho have occasion to use much wire usually 
 purchase the large sort, and reduce it themselves. 
 
 A liaiul macliine, represented in fig. 360, is used for this purpose. A is a 
 roller or cylinder, turning upon a vertical pin, fixed in the bench B; C a 
 
^WCB:E MiOTHFArTimE 
 
 from 357 to 362 
 
 362 
 
 FI. 49. 
 
 Keele <f Stvddir\ Strand 
 
 36if 
 
AND MACHINIST, 
 
 347 
 
 handle turned by manual labour ; E the draw-plate ; and a a the pins against 
 which it rests. The wire to be drawn is placed upon a reel D, which turns 
 upon a -vertical pin. This reel is sometimes placed on the table, and some- 
 times in a tub containing starch-water, or beer that has become acid. This 
 last is to loose the oxyd from the surface of the wire, which it has acquired 
 in the process of annealing. Fig. 361 represents a very simple and complete 
 wire-drawing machine, capable of drawing three wires at once. A K are 
 two rollers or barrels with cog-wheels, T V, on the ends of their axis. S is 
 a pinion wFich is turned round by means of a handle B, and communicates 
 motion to the cog-w^heels T V. Both these wheels are fitted upon round 
 parts of the axis of their respective rollers, so as to slip or turn freely round 
 with the same ; but a square is formed on the axis outside of the wheel, and 
 a clutch or catch, t or v, is fitted on this square part, so as to turn always 
 round with the axis. The catch is at liberty to slide upon the axis in the 
 direction of its length, by means of a lever W, which operates upon both 
 catches at once. When either of them is pushed back in contact with the 
 wheel, it intercepts two studs which project from the face of the wheel, and 
 then compels the axis or roller to turn round with the wheel ; but when the 
 catch is drawn aw'ay from the wheel, then the w-heel will slip round upon its 
 axis w'ithout communicating any motion. By means of the lever W, only 
 one wheel can be engaged at once, and the other must be free. The draw- 
 plate is firmly fixed betw'een the twu rollers, and it has a great many holes ; 
 the rollers are long enough to receive three wires at the same time. Each 
 roller has a groove in it parallel to the axis, into which a bar of metal is 
 fitted, and will exactly fill it up. 
 
 When the wires are introduced through the holes in the plate, the ends 
 are laid across this groove ; the bar is then put in and fastened by a simple 
 contrivance, and it fastens the ends of the wires beneath it, so that they be- 
 come attached to the roller ; then by turning the handle, B, round, the two 
 wheels are put in motion in contrary directions ; and that wheel which is 
 connected with its axle by its catch, will turn its banel round, and wind up 
 the wires so as to draw them through the plate E. The other roller being at the 
 same time detached, its wheel is at liberty to turn round in a contrary di- 
 rection to the wheel, as fast as the wires are drawn off from it. When the 
 whole length of the wires has been draw'n through the plate, they are de- 
 tached from the roller, the ends introduced through smaller holes in the 
 plate, and fastened again to the roller ; then the lever W is shifted, to dis- 
 engage that wheel which operated before, and engage the other. This being 
 done, the rollers will be turned in an opposite direction, and will w'ind back 
 the wires,' although the handle B is turned the same way round. 
 
 After the wire has been drawn three or four times, the metal becomes so 
 hard and fibrous that it would not draw^ any more without breaking ; it 
 therefore requires to be heated in the fire to restore its ductility ; for this 
 purpose it must be taken ofl’the barrels. A roller, M, is provided to wind the 
 wdre upon and draw it off from the barrel ; this roller is turned round by a 
 handle, m, fixed on the extremity of its axis ; and the wire wFich is w-ound 
 upon it in a coil is slipped off sideways. This machine is well adapted to be 
 worked by a mill, because the handle may ahvays be turned in the same way. 
 
 Fig 362 represents a machine that is used for reducing the w'ire to be 
 employed in the manufacture of musical instruments, or in making cards for 
 wool and cotton. A A A A are conical rollers, called blocks, each having 
 a bush, through which passes a vertical spindle. These spindles are con- 
 nected with wheel-work, situated beneath the bench, and being round are 
 capable of revolving without communicating motion to the rollers. When the 
 rollers are required to be engaged^ they are lifted up from tlte bench, till two 
 
THE OPERATIVE MECHANIC 
 
 348 
 
 knobs, fixed in the hollow part of each, come in contact with a cross-bar 
 fixed on the top of each spindle, which immediately carries them round. So 
 long as any wires are supplied by the reels E E E E, the stress of the wires 
 passing through the draw-plates will hold the rollers and spindles clasped 
 together ; but as soon as the whole of the wires have passed through the 
 draw-plates, the rollers will become disengaged, and fall upon the bench. 
 The tubs in which the reels are placed contain stale-beer grounds, or starch- 
 water, for the purpose which we have already noticed. 
 
 The French draw-plates are the most esteemed, and, in 
 time of war, a good French draw-plate has been sold for its 
 weight in silver. M. Du Hamel, in Les Arts et Metiers^ 
 vol. XV. gives the following account of the process of making 
 the draw-plates for the large iron- wire, 
 
 A band of iron is forged of two inches broad and one inch 
 thick. This is prepared at the great forge. About a foot in 
 length is cut off, and heated to redness in a fire of charcoal. It 
 is then beaten on one side with a hammer, so as to work all 
 the surface into furrows or grooves, in order that it may re- 
 tain the substance called the potin, which is to be welded 
 upon one side of the iron, to form the hard matter on which 
 the holes are to be pierced. This potin is nothing but frag- 
 ments of old cast-iron pots j but those pots which have been 
 worn out by the continued action of the fire are not good ; the 
 fragments of a new pot which has not been in the fire are 
 better. 
 
 The workman breaks these pieces of pots on his anvil, and 
 mixes the pieces with charcoal of white w’ood. He puts this 
 in the forge, and heats it till it is melted into a sort of paste ; 
 and to purify it he repeats the fusion ten or twelve times, and 
 each time he takes it with the tongs to dip it in water. M. Du 
 Hamel says, this is to render the matter more easy to break 
 into pieces. 
 
 By these repeated fusions with charcoal, the cast-iron is 
 changed, and its qualities approach those of steel, but fur 
 from becoming brittle, it will yield to the blows of the ham- 
 mer and to the punch, which is used to enlarge the holes. 
 The bar of iron which is to make the draw-plate is covered 
 with a layer of pieces of the potin, or cast-iron thus prepared. 
 It is applied on the side which is furrowed, and should occupy 
 about half an inch in thickness. The whole is then wrapped 
 up in a coarse cloth, which has been dipped in clay and water, 
 mixed up as thick as cream, and is put into the forge. The 
 potin is more fusible than the forged iron, so that it will melt. 
 The plate is withdrawn from the fire occasionally and ham- 
 mered very gently upon the potin, to weld and in some mea- 
 i^ure amalgamate it with the iron, which cannot be done at 
 
AND MACHINIST. 
 
 34y 
 
 once; but it must be repeatedly heated and worked until the 
 potin fixes to the iron. The workman then throws dry pow- 
 dered clay upon it, in order, they say, to soften the potin. 
 
 The union being complete, the plate is again heated, and 
 forged by two workmen, w^ho draw out the plate of one foot 
 to a length of two feet, and give it the form it is to have. It 
 is well known that cast-iron cannot be worked at the forge 
 without breaking under the hammer ; but in the present in- 
 stance, it is alloyed with the iron-bar, and is drawn out with 
 it. It has also acquired new properties by the repeated 
 fusions with charcoal. 
 
 The holes are next pierced whilst the plate is hot. This is 
 done with a well-pointed punch of German steel, applied on 
 that side of the plate which is the iron-bar. It requires four 
 heats in the fire to punch the holes, and every turn a finer 
 punch is employed, so as to make a taper hole. The makers 
 of draw-plates do not pierce the holes quite through, but 
 leave it to the wire-drawers to do it themselves when the 
 plate is cold, with sharp punches, and then they open the 
 hole to the size they desire ; and although this potin is of a 
 very hard substance, the size of the hole may be reduced by 
 gentle blows with a hard hammer, on the flat surface of the 
 plate round the hole. 
 
 A great many holes are made in the same plate ; and it is 
 important that they should diminish in size by very imper- 
 ceptible gradations ; so that the workman can always choose 
 a hole suitable for the wire he is to draw, without being 
 obliged to reduce it too much at once. 
 
 To ascertain the size of the wire, three kinds of gauges are 
 used. The one is made of a piece of wire bent in zigzag, 
 with a space of a different width between every bend ; another 
 is made of a steel-plate with notches on the edge ; and the 
 other, which is the most accurate, consists of two straight 
 rules of steel put together at an angle. The diameter of the 
 wire in this last is indicated by the depth to which it will 
 enter into the angle ; the edges of the rules are divided into 
 equal parts for that purpose, and numbered, to correspond 
 with the different sizes of the wire. 
 
 The wire manufactory of Messrs. Mouchel, situated at 
 L’Aigle, in the department of L'Orne, is one of the most 
 considerable in France. It furnishes annually in cards for 
 wool-combing only, 100,000 quintals of iron wire, each 
 100 lbs. A part of this is consumed in France, and the 
 rest is exported to Spain, Italy, Portugal, and even to the 
 shores of the Levant. 
 
350 
 
 TffE OPERATIVE MECHANIC 
 
 They employ the iron manufactured in the departments of 
 L’Orne and La Haute Soane, as being of the best quality. 
 The first produces the best wire for making screw s, nails, and 
 pins, as much on account of its hardness as its fine polisih, which 
 resembles steel-wire. In this respect, it is superior to the 
 iron of Haute Soane ; but from its ductility the latter can now 
 be made extremely fine, and it appears to be most free from 
 heterogeneous particles. 
 
 The smelted iron, prepared and hammered, being in a state 
 nearly fit for their purpose, is transported at a small expense 
 to L’Aigle, by the rivers and canals. They have a forge to 
 reduce the steel and iron of Normandy, which arrives in large 
 pieces, into small and regular bars. 
 
 When the iron is formed into an irregular bar of about a 
 centimetre, near four- tenths of an inch in diameter, they be- 
 gin to draw it into ware. Although it be already much extended 
 by hammering, it is in the first place passed four times 
 through the drawing-plate ; then its molecules become dis- 
 posed lengthways, and exhibit fibres at their utmost exten- 
 sion. The fibres must be removed by means of heat, which 
 disperses and divides them; and after that the wire may 
 again be reduced three numbers. The fibres wdiich are re- 
 produced by this operation are again removed by heat. The 
 whole process is five times repeated, consequently the ware 
 is passed through fifteen numbers ; after wdiich, a single ex- 
 posure to the fire is sufficient to fit it for passing six others, 
 whereby it is reduced to the thickness of a knitting-needle. 
 
 The steel-wire, being much harder, requires to be passed 
 through forty-four numbers, and to be annealed every other 
 time. 
 
 The machine which drawls the steel-wdre, must go slower 
 than that which di\ws the iron ; for the first being very 
 hard, and offering more resistance to the drawing-plate, 
 should be pulled out with more care, since the quickness ought 
 to be proportioned to the resistance, and reciprocally ; and 
 if they depart from this principle the results will vary. Thus, 
 for example, the iron of the department of L’Orne, which is 
 more compact than that produced at Haute Soane, if drawn 
 by the same machines, augments to hardness, and is weakened 
 when it is brought to too great a degree of fineness. But this 
 iron, w’hich is very hard, and capable of receiving a very high 
 polish, is to be preferred for certain uses. 
 
 In order to anneal the wire,, they formerly employed a 
 large and elevated fur-nace, wdth bars of cast-iron to support 
 the wire in the middle of the flames. It contains 
 
AND MACHINIST. 
 
 351 
 
 pounds weight, so contrived as to contain equal portions of 
 each number. They are so arranged that the thickest wires 
 receive the strongest heat ; therefore, the whole is equally 
 heated in the same space of time. 
 
 The operation lasts three hours with a fire well kept up, 
 and it might be imagined that this apparatus was completely 
 adapted to the purpose ; but there are imperfections in this 
 method, because it leaves the wire exposed to the contact of 
 the atmospheric air, the oxygen of which it seizes with extreme 
 avidity ; whence a considerable quantity of oxyd is occasioned, 
 and also an operation to free it from the scales, which consists 
 of beating the bundles of wire with a wooden hammer wetted 
 wdth water. 
 
 Notwithstanding this precaution, there often remains a 
 portion of oxyd adhering to the surface of the metal, which 
 streaks the draw-plate, or fixes on the wire, and gives it a 
 tarnished appearance, and causes it to break when it is brought 
 to a great degree of fineness. This furnace is only used for 
 the steel-wire, or the iron from L’Orne, which is less liable 
 to change ; and besides, being harder, is not easily attacked 
 by the oxygen. 
 
 In order to diminish the waste that the fire occasions, they 
 have contrived another process, which consists in dipping the 
 bundles of wire into a basin of wet clay before they put them 
 into the furnace ; and they are left in the furnace to dry 
 before the fire is lighted, without which precaution the clay 
 would peel off from the iron. 
 
 For making wire for cards, M. Mouchel invented another 
 furnace. It is round, and about one metre six decimetres 
 in diameter, and one metre eight decimetres in height, without 
 including its parabolic arch, and the chimney above it. The 
 interior is divided by horizontal grates into three stories ; the 
 lo^vest receives the cinders, the second is the fire-place, and 
 into the third, or upper place, they slide a roleau of wdre, 
 w'eighing 150 kilogrammes, which is enclosed in a space 
 comprised between two cast-iron cylinders, being luted to 
 prevent the admission of air between them. The flames 
 circulate about the outside of the first, and within the interior 
 of the second, which defends the wire from atmospheric air. 
 The diameter of the largest cylinder is about one metre four 
 decimetres ; that of the second one metre ; thus the space 
 comprised between them is two decimetres, on an elevation 
 of five decimetres. There must be several pair of cylinders 
 provided, because whilst one pair is in the furnace, another 
 must be. prepared to receive a fresh roleau of wire 5 they are . 
 
352 
 
 THE OPERATIVE MECHANIC 
 
 changed every hour by means of a long iron lever, with whicli 
 a single man can easily push them in, and draw them out 
 again, as the cylinder slides on cast-iron rails. 
 
 They are very careful not to open the cylinders imme- 
 diately on their being drawn out of the fire ; for the roleaus 
 of wire contained in them, being still red, would oxydate 
 quite as much as if they had been heated in the midst of the 
 flames without the least precaution. 
 
 The opening contrived for the passage is on the side, and 
 has a door of cast-iron, with a groove which winds round the 
 furnace ; the fire-place has one something similar to it ; that 
 of the ash-hole is vertical, in order that it may be raised to 
 increase the fire at will. 
 
 When the iron-wire is reduced to the thickness of a knitting- 
 needle, it is made up into bundles of 1 25 kilogrammes (275 lbs.) 
 each, into a large iron vessel, in order to anneal it sufficiently 
 to be reduced for the last time. This vessel is placed upside- 
 down in the middle of a round furnace, which is so con- 
 structed as to sustain burning coals all round it, and of which 
 it consumes 35 kilogrammes (77 Ihs.) before the operation is 
 completed. The cover must be carefully luted, as the slightest 
 admission of air is sufficient to burn the external surfaces of 
 the wire to an oxyd, which cannot afterwards be reduced. 
 
 When one of these vessels is sufficiently heated, it is filled 
 with water containing three kilogrammes (six pounds and 
 a half) of tartar, and suspended over the flames of the furnace 
 to make it boil ; this solution, without attacking the metal, 
 frees it from the grease and the little oxyd that adheres to it. 
 This is the last operation in which the wire is exposed to the 
 fire, and it is then in the proper state for being reduced to 
 the utmost degree of fineness it is capable of sustaining, and 
 will preserve enough of the effect of the annealing to require 
 it no more ; but when the natural hardness of the iron varies, 
 this last exposure to the fire should take place in proportion 
 to its thickness. As steel loses its capacity of extension much 
 sooner than iron, it is annealed until it is no thicker than a 
 sewing-needle. The space which is left in the vessel is filled 
 up with charcoal-dust, which prevents it from losing the 
 quality of steel, and preserves the heat long enough to give 
 it the proper degree of pliancy. 
 
 As Messrs. Moucbel always use iron and steel at the same 
 manufactory, they have been able to reduce their operations 
 to a general system ; and to attain this end, have determined 
 a graduated scale, by which the wire will not be more stretched 
 in the drawing-plate in one number or size than another. 
 
AND MACHINIST. 
 
 353 
 
 The following is the method they contrived, in order to form 
 this scale for the iron- wire : — They take a certain quantity of 
 various thicknesses, which has been drawn as fine as the iron 
 would bear; the smallest size is 100,000 metres (109,333 
 yards) in length to the kilogramme, 2*2 pounds avoirdupois f 
 they note the weight that each might be capable of supporting 
 without breaking ; this being expressed by figures, it is easy/ 
 by a few interpolations, to express them in a progressive 
 form. This kind of scale has been partly formed by comparing 
 the weight of the different sizes with equal lengths, from 
 which gauges or calibres may be made for the use of the 
 workman. These gauges are certain guides, which they 
 cannot mistake, except through great carelessness. If they 
 had not these gauges, they would often pass the wire through 
 holes in the drawing-plates that are too large for it, whence 
 it does not acquire the strength it should have in proportion 
 to its thickness, and loses its hardness ; they might also pass 
 it through holes that were too small, which would weaken it, 
 and render it very brittle. In the latter case, it frequently 
 happens that the steel of the drawing-plate, being unable 
 to sustain the force to which it is exposed, will give way,- 
 as if the plate were too soft ; and the wire will be brittle 
 at the beginning, and soft and too thick at the other 
 extremity. 
 
 The greatest part of the fine wire at Messrs. Mouchel’s: 
 manufactory is drawn by workmen who are dispersed about 
 the country ; but they have also a machine which moves 
 twenty-four bobbins in a horizontal direction, which only 
 requires the workmen to look after it. It is upon the bob- 
 bins that the MUre is reduced to the different degrees of thin- 
 ness desired ; therefore this is the last operation in the art of 
 making iron and steel wire, although it has all requisite quali- 
 ties given to it in the workshop of the wire-drawer. 
 
 Wire is still incapable of being made into needles and 
 carding-hooks until it has undergone another operation for 
 dressing and straightening the wire, by which it is made to 
 lose the bend or curve that it acquires on the bobbins. 
 
 This work consists in drawing the wire between pins fixed 
 on a piece of wood, and which act to bend the wire, first in 
 one direction and then in the opposite, nn a waving line, of 
 which the waves are at first larger, but decrease gradually, 
 and the last bend of which tends to force the wire into a 
 straight line. The dresser is obliged constantly to adjust the 
 pins, by inclining or raising them with strokes of the hammer. 
 Also, for each number of wires, the pins must be at different 
 
354 
 
 THE OPERATIVE MECHANIC 
 
 and calculated distances. This requires a workman of inteU 
 Hgence, diligence, and address. 
 
 An ingenious instrument is now appropriated to this opera- 
 tion, and removes all difficulty. Six little puppets of very 
 hard steel are substituted for the nails of the ordinary instru- 
 ment, and are fixed on parallel bars of metal, so jointed toge- 
 ther that the movement of them all will be parallel, and the 
 puppets are widened or brought nearer together by screws ; 
 the wire is drawn between these puppets in a zigzag or 
 waving line, and the repeated flexures break the sinuosities of 
 the wire. There is a conductor of the wire to the puppets, 
 and another conductor which serves to prevent the wire from 
 being shaken. There are slight grooves at the extremity of 
 the puppets, to give a passage to the wire. A scale sustained 
 by a screw indicates the distance at which the puppets should 
 be placed from each other, to straighten each size of wire ; 
 this forms nearly an invariable rule, and the dresser saves a 
 third of the time which is employed in regulating the pins 
 of the instrument formerly used. There is nothing more to 
 be done but to draw out the wire by means of a wheel, on 
 which he reels it, and then form, it into bundles to be deli- 
 vered to the consumers. 
 
 The steel wire of France is proper for many puq>oses. It 
 is brought from Messrs. Mouchel for making knitting-needles 
 in the English fashion, shoemakers" needles, and other similar 
 articles ; it may be also used for needles of all sizes, and 
 even for cards for wool-combing ; but as this steel is much 
 more expensive than the iron- wire, it is very seldom used for 
 the latter purpose. 
 
 The method of preparing the draw-plates is described by 
 Messrs. Mouchel, and is different from that before described. 
 
 For making wire for cards, two sorts of drawing-plates are used, large 
 and small ones ; the first, for the sort of wire that we have been describing, 
 is drawn with the pincers, as fig. 359, and with the bobbin or roller, which 
 is a cylinder, adapted to the axis turned by the water-mill, and is used in 
 preference, to avoid the marks made on the wire by the pincers ; the small 
 drawing-plates are used for such wire as may be drawn by hand. The steel 
 xvhich they employ fo#%hese drawing-plates should never vary in quality, 
 except that the smallest pieces are made of the finest steel. Several pieces 
 of iron are disposed in the furnace in the form of a box without a lid, their 
 weight being according to the use for which they are intended to be made. 
 The workman fills each of these boxes with cast-steel, and having covered 
 it over with a luting of clay, it is exposed to a fierce fire until the steel be 
 melted. Ilis art consists in seizing the proper moment to withdraw the 
 plate from the fire ; he raises the luting, and blows on it through a tube, in 
 order to drive off all heterogeneous parts, and then amalgamates it with the 
 iron by light blows ; after it is cool, he replaces it at the fire, where the 
 fusion again takes place, but to a less degree than before; he afterwards 
 
AND MACHINIST. 
 
 355 
 
 works the steel with light blows of the hammer, to purify and solder it with 
 tlie iron. This operation is repeated from seven to ten times, according 
 to its quality, which renders it more or less difficult to manage. During 
 this process, a crust forms on the steel, which is detached from it the fifth 
 time of its exposure to the fire, because this crust is composed of an oxydated 
 steel of an inferior quality. It sometimes liappens that two, and even three, 
 of these crusts are formed of about two millimetres, or one-sixteenth of an 
 inch, in thickness, which must also be removed. 
 
 After all these different fusions, the plate is beaten by a 
 hammer wetted with water, and the proper length, breadth, 
 and thickness, are given to it. When thus prepared, the 
 plates are heated again, in order to be pierced with holes by 
 punches of a conical form ; the operation is repeated five or 
 six times, and the punches used each time are progressively 
 smaller. It is of importance that the plate never be heated 
 beyond a cherry-red, because if it receives a higher degree of 
 heat, the steel undergoes an unfavourable change. The plates, 
 when finished, present a very hard material, which neverthe- 
 less will yield to the strokes of the punches and hammer, 
 which they require when the holes become too much enlarged 
 by the frequent passing of the wire through them. 
 
 When the plates have been repaired several times, they 
 acquire a degree of hardness which renders it necessary to 
 anneal them, especially when they pass from one size to 
 another ; sometimes they do not acquire the proper quality 
 until they have been annealed several times. Notwithstanding 
 all the precautions which are taken in preparing the plates, 
 the steel still varies a little in hardness, and according to this 
 variation they should be employed for drawing either steel or 
 iron wire ; and if the workman who proves them finds that 
 they are too soft for either the steel or iron, they are put 
 aside, to be used by the brass- wire drawers. 
 
 A plate that is best adapted for drawing of steel-wire is 
 often unfit for the iron ; for the long pieces of this latter 
 metal will become smaller at the extremity than at the begin- 
 ning, because the wire, as it is drawn through the plate, is 
 insensibly heated, and the adhering parts are swelled, conse- 
 quently pressed and reduced in size towards the latter end^ 
 The plates that are fit for brass are often too soft for iron, 
 and the effect resulting is the reverse of that produced by 
 a plate that is too hard. 
 
 The smallest plates which Messrs. Mouchel use are at the 
 least two centimetres, or eight-tenths of an inch, in thickness, 
 so that the holes can be made sufficiently deep ; for when 
 they are of a less thickness, they will seize the wire too sud-^ 
 denly, and injure it. 
 
 2 A 2 
 
356 
 
 THli OPERATIVE MHCIIANiC 
 
 This inconvenience is much felt in manufactories where 
 they continue to use the plates for too long a time^ as they 
 become exceedingly thin after frequent repairs. One of 
 Messrs. Mouchel’s large plates reduces i,400 kilogrammes 
 (3,080 lbs. avoirdupois) from the largest size of wire to N° 6, 
 which is of the thickness of a knitting-needle ; 400 kilo- 
 grammes (880 lbs.) of this number are afterwards reduced in 
 one single small plate to N® 24, which is carding-wire ; and 
 to finish them,- they are passed through twelve times suc- 
 cessively. 
 
 Wires are frequently drawn so fine as to be wrought along 
 wdth other threads of silk, wool, or hemp ; and thus they 
 become a considerable article in the manufactures-. 
 
 Dr. Wollaston, in 1813, communicated to the Royal Society 
 the result of his experiments in drawing wire, liaving re- 
 quired some fine wire for telescopes, and remembering that 
 Muschenbrock mentioned wire 500 feet of which w^eighed 
 only a single grain, he determined to try the experiment, 
 although no method of making such fine wire had ever yet 
 been published. With this view, he took a rod of silver, 
 drilled a hole through it only one-tenth its diameter, filled this 
 hole with goldj and succeeded in drawing it into wire till it 
 did not exceed the three or four thousandth part of an inch, 
 and could have thus drawn it to the greatest fineness percep- 
 tible by the senses. Drilling the silver he found very trou- 
 blesome, and determined to try to draw' platina-wire, as that 
 metal w'ould bear the silver to be cast round it. In this he 
 succeeded with greater ease, drew the platina to any fineness, 
 and plunged the silver in heated nitric-acid, which dissolved 
 it, and left the gold or platina wire perfect. 
 
 LEAD MANUFACTURE. 
 
 Lead ore is found in most parts of the world.- In Britain 
 the principal lead-mines are situated in Cornwall, Devonshire, 
 and Somersetshire ; in Derbyshire, Durham, Lancashire, 
 Cumberland, and W estmoreland ; in Shropshire, Flintshire, 
 Denbighshire, Merionethshire, and Montgomeryshire ; at the 
 lead-hills in Scotland, on the borders of Dumfrieshire and 
 Lanarkshire, in Ayrshire, and at Strontian in Argyleshire. 
 
 The smelting of the ore is performed by either a blast- 
 furnace, called an ore-hearthj or a reverberatory-furnace. 
 In the former method, the ore and fuel are mixed top’ether. 
 
AND MACHINIST. 
 
 357 
 
 and exposed to the action of the blast, which quickly fuses 
 the metal, and causes it to fall into the lower part of the 
 hearth, where it is protected from the oxygen of the blast 
 by the scoria that floats upon its surface. 
 
 When the fluid lead is tapped, or drawn off, a sufficient 
 quantity of it is left in the furnace to float the liquid scoria ; 
 but v/hen the whole of the lead is to be drawn off, the blast 
 is stopped, and some lime is thrown into the furnace to con- 
 crete the scoria, while the lead is run out. 
 
 In smelting by the reverberatory-furnace, which is uu- 
 doubtedly the best in places where there is an ample supply 
 of coal, the fire is made at one end, and the flame passes over 
 the hearth, and enters into an oblique chimney, which ter- 
 minates in a perpendicular one, called a stack, of considerable 
 height. The length of the hearth, from the place where the 
 lire enters to the chimney, is about eleven feet, two of which 
 constitute the throat of the furnace ; the remainder forms a 
 concave surface, four and a half feet wide at the throat of the 
 furnace, seven feet four inches at the distance of two feet from 
 the throat, seven feet two inches in the middle of the hearth, 
 five feet eleven inches at two feet distance from the chimney, 
 and two feet ten inches where the flame enters the chimney 
 at two apertures, each ten inches square ; the throat of the 
 furnace is two feet long, four feet wide, and six inches deep ; 
 the length of the fire-place four feet, equal to the width of 
 the throat ; its width two feet, and depth three feet, from the 
 grate up to the throat of the furnace; the section of the 
 oblique chimney is sixteen inches square, and of the perpen- 
 dicular twenty inches, supposing a straight horizontal line 
 drawn from the lower plane of the throat of the chimney to 
 the opposite side of the furnace ; the lower part of the con- 
 cave hearth, which is in the middle of this cavity, is nineteen 
 inches below this line, the roof of the furnace being seventeen 
 inches above the same line ; the rest of the hearth is conform- 
 ably concave. 
 
 The furnace on one side has three openings, about ten 
 inches square, at equal distances from each other, and pro- 
 vided with iron doors, which can be removed as occasion may 
 require. Besides these apertures, which are for the purpose 
 of raking and stirring the ore, &c. and consequently, upon 
 a level with the horizontal line above alluded to, there are 
 two others of smaller dimensions, the one to tap the liquid 
 lead, the other the scoria. The ore is introduced by a vessel 
 pi the shape of a hopper placed in the roof of the furnace. 
 
 The ores of lead, similarly to those of iron and most other 
 
358 
 
 THE OPERATIVE MECHANIC 
 
 metals, are combined with various kinds of earthy matter, 
 which require them to be well pounded before they are intro- 
 duced into the reverberatory or smelting furnace. The pound- 
 ing is sometimes performed by women using hammers, and 
 sometimes the ores are pounded or crushed by causing them 
 to pass through iron rollers loaded with great weights. After 
 the ores have been pounded or crushed, the earthy matter 
 is separated by washing. 
 
 The powder to be washed is put into a riddle or sieve, and 
 placed in a large tub full of water ; when, by a certain mo- 
 tion, the lighter or earthy parts are separated and thrown 
 over the edge of the riddle, while the metal, which, as we 
 have before stated, is always considerably heavier than its 
 accompanying ingredients, is retained. There are some im- 
 j)urities, however, which cannot be sejjarated by this process, 
 consisting principally of blmd, or black-jack, called mock ore, 
 and pyrites, or sulphuret of iron, named Brazil, 
 
 In the process of smelting, the ore is spread upon the con- 
 cave hearth, so that the flame may act upon it, and release 
 the sulphur. When the sulphur has escaped, the lead com- 
 bines with oxygen, and the oxyd of lead, thus formed, com- 
 bines with and reduces the earthy matter to a liquid, which 
 floats upon the surface of the metal, and for the remainder of 
 the operation, protects it from the action of the oxygen. The 
 temperature of the furnace is now considerably raised, to 
 separate as quickly as possible the lead from the liquid scoria ; 
 after which a ccmsiderable portion of the scoria is tapped off, 
 leaving only so much behind as is necessary to protect the 
 metal from the action of the oxygen. The fire is now slackened, 
 and a quantity of slack, or refuse pit-coal, thrown into the 
 furnace, which serves to diminish the heat, and to concrete the 
 melted scoria ; though this last part of the process is not well 
 done unless powdered lime be also added. The scoria being 
 now hardened, is broken to pieces by a rake, and thrust to 
 the opposite side of the furnace, where it is taken out through 
 the apertures already mentioned. 
 
 The lead is now tapped, in a manner similar to that de- 
 scribed in the manufacture of iron, and is allowed to run into 
 a large iron pan, from whence it is laded into moulds to cast 
 into pigs. When the ores abound with blind, or black-jack, or 
 sulphate of iron, it becomes necessary to add the fluat of lime, 
 as a flux. 
 
 The scoria is still found to contain some lead, independent 
 of that in the state of oxyd, and chemically combined with it, 
 and is consequently exposed to the heat of another furnace, 
 
AND MACHINIST. 
 
 35D 
 
 being a species of biast, and called a slag-hearUi, which fuses 
 the scoria, and causes the metal to penetrate through it, and 
 fall into a cavity, where it is protected from the agency of 
 the blast, and from whence it is taken and cast into pigs. 
 
 As all lead ores contain more or less of silver, we shall 
 extract from Dr. Rees’s Cyclopaedia the method by which the 
 silver, by the oxydation of the lead, is extracted. 
 
 shallow vessel, or cupel, is filled with prepared fern-ashes 
 well rammed down, and a concavity cut out for the reception 
 of the lead, with an opening on one side for the mouth of the 
 bellows, through which the air is forcibly driven during the 
 process. The French smelters cover the surface of the ashes 
 with hay, and arrange symmetrically the pieces of lead upon 
 it. When the fire is lighted, and the lead is in a state of 
 fusion from the reverberation of the flame, the blast from 
 the bellows is made to play forcibly on the surface, and in a 
 short time a crust of yellow oxyd of lead, or litharge, is 
 formed, and driven to the side of the cupel opposite to the 
 mouth of the bellows, where a shallow side or aperture is 
 made for it to pass over ; another crust of litharge is formed 
 and driven off*, and this is repeated in succession till nearly 
 all the lead has been converted into litharge and driven off. 
 The operation continues about forty hours, when the complete 
 separation of the lead is indicated by a brilliant lustre on the 
 convex surface of the melted mass in the cupel, which is 
 occasioned by the removal of the last crust of litharge that 
 covered the silver. The French introduce water through a 
 tube into the cupel, to cool the silver rapidly, and prevent its 
 spirting out, which it does when the refrigeration is gradual, 
 owing probably to its tendency to crystallize. In England 
 the silver is left to cool in the cupel, and some inconvenience 
 is caused by the spirting, which might be avoided by the 
 former mode. 
 
 The silver thus extracted is not sufficiently pure ; it is 
 again refined in a reverberatory-furnace, being placed in a 
 cupel lined with bone ashes, and exposed to greater heat ; 
 the lead which has escaped oxydation by the first process, is 
 converted into litharge, and absorbed by the ashes of the 
 cupel. 
 
 The last portions of litharge in the first process are again 
 refined for silver, of which it contains a part which was driven 
 off with it. The litharge is converted into lead again by 
 heating it with charcoal ; part is sometimes sold for pigment, 
 or converted into red-lead. The loss of lead by this process 
 differs considerably, according to the quality of the lead. 
 
360 
 
 THE OPERATIVE MECHANIC 
 
 The litharge commonly obtained from three tons of lead 
 amounts to 58 hundred weight ; but when it is again reduced 
 to a metallic state^ it seldom contains more than 52 hundred 
 weight of lead, the loss on three tons being eight hundred 
 weight. The Dutch are said to extract the silver from the 
 same quantity of lead with only the loss of six hundred 
 weight.^’ 
 
 Having explained the process by which pig-lead is ex- 
 tracted from the ores, it now remains for us to show the 
 methods by which pig-lead is manufactured into sheet-lead, 
 or into the tubes called lead-pipes. 
 
 In the manufacture of sheet-lead, the ingots or pigs are put 
 into a large caldron or furnace built with free- stone and 
 earth. Near this furnace is the table or mould on which the 
 sheet is to be cast ; it is made of large pieces of wood, well 
 jointed, and bound at the ends with bars of iron, and has 
 a ledge or border of wood, about two or three inches thick, 
 and one or two high, called the sharps. The tables are 
 usually about three or four feet wide, and from eighteen to 
 twenty feet long. The table is covered with very fine sand, 
 which is prepared for the casting by moistening it with clear 
 water, working it together with a stick, beating it flat with 
 a mallet, and smoothing it with a piece of brass or wood. 
 
 A long narrow piece of wood, with notches cut in each end 
 so as to fit the ledges, is placed over the table, and is so 
 arranged, that the space between it and the sand shall be 
 proportionate to the intended thickness of the plate. The 
 workman gradually slides the strike from one end of the 
 table to the other, by which means he obtains a sheet of the 
 requisite, and in all parts of equal, thickness. 
 
 At the top of the table is a large triangular iron peel or 
 shovel, with its fore part bearing upon the edge of the table, 
 and the hinder part on a tressel, somewhat lower than the 
 table ; the design of which is, to prevent the liquid metal 
 running off at the fore side, where there is no ledge. The 
 metal being sufficiently fused, is taken out of the furnace or 
 caldron with a large iron ladle, and is put into the peel, 
 where it is cleansed of its impurities by using another large 
 iron ladle pierced like a scummer. The handle of the peel is 
 now raised, which causes the liquid metal to run into the 
 mould, while the workman, with the strike, regulates the 
 thickness. When the sheet is of the required thickness, 
 the handle of the peel is lowered, and the sheet is allowed to 
 cooL When set, the edges on both sides are planished iu 
 order to render them smooth and straight. 
 
AND MACHINIST, 
 
 361 
 
 The method above described is only used in casting large 
 sheets of lead ; in casting sheets of smaller dimensions, the 
 table or mould, which is placed in an inclined position, is, in 
 lieu of sand, covered with a piece of woollen stuff, nailed 
 down at both ends, and over that is placed a very fine linen 
 cloth. 
 
 In this process great attention must be paid to the heat 
 of the liquid metal, and a piece of paper is used as a test ; 
 if the paper take fire, the lead is too hot, and W'ould de- 
 stroy the linen ; if it be not shrunk and scorched, it is not 
 hot enough. 
 
 When the sheets are required to be very thin, it is neces- 
 sary to make the peel and strike of one piece. It is a kind 
 of wooden box without a bottom, being closed only on three 
 sides j the back of it is about seven or eight inches high, and 
 tlie two sides, like two acute angles, diminish to the top j the 
 width of the middle makes that of the strike, which again 
 makes that of the sheet to be cast. 
 
 The strike is so placed, that the highest part is towards 
 the lower, and the two sloping sides towards the upper end 
 of the table. The top part of the table, where the metal is 
 poured in, is covered with a pasteboard, which serves as a 
 bottom to the case, and prevents the linen from being burnt 
 while the metal is pouring in. 
 
 The strike or peel being filled with lead, according to the 
 intended size of the sheet, two men, one at each side, seize 
 hold of it, and with greater or less velocity, as the sheet is to 
 be more or less thick, force it down the inclined table ; for 
 the thickness of the sheet always depends upon the velocity 
 with which the strike slides down the table. The sheet-lead, 
 after casting, is frequently reduced by rollers. 
 
 As this particular department is so intimately connected 
 with the business of a plumber, we shall not be considered 
 as departing from the subject by inserting the following 
 tables, from Hutton's Mensuration, 
 
 Plumber’s work is commonly estimated by the pound or 
 hundred weight ; but the weight may be discovered by the 
 measure of it, in the manner below stated. Sheet-lead used 
 in roofing, guttering, &c. is commonly between seven and 
 twelve pounds weight to the square foot ; but the following 
 table shows by inspection the particular weight of a square 
 foot for each of several thicknesses. 
 
362 THK OPERATIVE MECHANIC 
 
 Thickness. 
 
 Pounds 
 
 to a square foot. 
 
 Thickness. 
 
 Pounds 
 
 to a square foot. 
 
 •10 
 
 5-899 
 
 •15 
 
 8-848 
 
 •11 
 
 6-489 
 
 •16 
 
 9-438 
 
 1 
 
 TJ 
 
 6-554 
 
 1 
 
 TT 
 
 9-831 
 
 •12 
 
 7-078 
 
 •17 
 
 10-028 
 
 1 
 
 ¥ 
 
 7-373 
 
 •18 
 
 10-618 
 
 •13 
 
 7-668 
 
 •19 
 
 11-207 
 
 •14 
 
 8-258 
 
 •2=* 
 
 11-797 
 
 1 
 
 T 
 
 8-427 
 
 .21 
 
 12-387 
 
 In this table the thickness is set down in tenths and hun- 
 dredths, &c. of an inch ; and the annexed corresponding 
 numbers are the weights in avoirdupois pounds and thou- 
 sandth parts of a pound. So the weight of a square foot of 
 or of an inch thick is 5 pounds and of a pound ; 
 and the weight of a square' foot to one-ninth of an inch 
 thickness is 6 pounds and -iWo- of a pound. Lead pipe 
 of an inch bore is commonly 13 or 14 pounds to the yard in 
 length. 
 
 Examples : 
 
 1. How much weighs the lead which is 39 feet 6 inches long, and 3 feet 
 3 inches broad, at 8§ lbs. to the square foot ? 
 
 
 Duodecimals. 
 
 Decimals. 
 
 39- 6 
 
 39-5 
 
 3- 3 
 
 H 
 
 118- 6 
 
 118-5 
 
 9-10-6 
 
 9*875 
 
 128- 4-6 
 
 128-375 
 
 
 
 — 
 
 
 1024 
 
 1027-000 
 
 64 
 
 64-1875 
 
 
 
 ()1 7 
 
 1091*1875 
 
 Answer. 1091^®^ibs. 
 
 2. What cost the covering and guttering of a roof with lead, at 1 8 j. per 
 cwt. ; the length of the roof being 43 feet, and the breadth or girth over it 
 32 feet, the guttering 57 feet long, and 2 feet wide ; the former 9,831 lbs. 
 and the latter 7,373 lbs. to the square foot? — Answer, 115?. 9«. l^c? 
 
 It is now time to direct our attention to the manufacture 
 of lead pipes, which are universally employed for small 
 water-pipes, from the facility of bending them in any direc- 
 tion, and soldering their joints. 
 
 Lead pipes are sometimes cast in an iron mould, made in 
 two halves, forming, when put together, a hollow cylidner, 
 of the size of the intended pipe ; in this cylinder, or mould, 
 is put an iron rod or core, extending from the top to the 
 
AND MACHINIST. 
 
 363 
 
 bottom, and leaving all round a space between it and the 
 cylinder of the intended thickness of the pipe. The lead is 
 poured in at a spout, formed by two corresponding notches 
 cut in each half of the mould ; and a similar hole is made at 
 another place for the escape of air. The mould is fastened 
 down upon a bench, upon which, at one end, and in a line 
 with its centre, is a rack, moved by toothed-wheels and 
 pinions. 
 
 When the pipe is cast, a hook at the end of the rack is put 
 into an eye at the end of the iron core, which, by the action 
 of the cog-wheels and pinions, is drawn so far out, that about 
 two inches of it only remain in the end of the pipe ; the two 
 halves of the mould, which fasten together by wedges or 
 screws, are now separated from the pipes, and are fastened 
 upon the iron core, and the two inches of lead pipe attached 
 to it; melted lead is again poured into the mould, which, 
 uniting with the end of the first piece, forms the pipe of con- 
 siderable length ; and the operation is repeated till it be of 
 the length required. 
 
 Another and a much better method is, to cast the lead in an 
 iron mould upon a cylindrical iron pipe, of a size proportioned 
 to the bore of the pipe to be made, and leaving a space be- 
 tween the core and the mould three or four times the thick- 
 ness of the intended pipe, and in short lengths, w'hich are 
 afterwards drawn through holes in pieces of steel, similar to 
 the process of wire-drawing, till the pipe is reduced to the 
 required thickness. 
 
 Another method is that for which the celebrated iron- 
 manufacturer, Mr. John Wilkinson, of Brosely, took out a 
 patent in 1790, and which, since the expiration of his patent, 
 has been successfully practised by many other manufacturers. 
 This method consists in casting a circular piece of lead, about 
 eighteen inches long, with a core or hole longitudinally 
 through its centre. This piece is of considerably larger 
 diameter than that of the pipe intended to be made. The 
 core or hole at one extremity suddenly decreases, so as to 
 form on the internal surface of the piece of lead a stop or 
 shoulder, against which a polished iron triblet or mandrel, 
 which has been passed thus far along the core, rests. This 
 triblet or mandrel is of somewhat greater length than the 
 length required of the pipe to be manufactured, which, 
 generally speaking, is from seven to nine feet. An iron screw, 
 having a loop at the opposite end, is then passed down the 
 other end of the core, and is screwed into that part of the 
 mandrel which rests against the shoulder. In this state 
 
364 
 
 THB OPERATIVE MECHANIC 
 
 the mandrel, with the circular piece of lead fixed fast on it, is 
 taken to the drawing-table. 
 
 The drawing-table in the principle of its operation resem- 
 bles the block described in the Wire Manufacture in every 
 respect, though it is far more powerful. The table generally 
 used is about thirty feet long, by two feet wide ; having at 
 one end a powerful cylinder with a chain attached to it. 
 This cylinder receives motion from a steam-engine, or other 
 first mover, and can be thrown in and out of geer by an adapt- 
 ation of any one of the appropriate modes described under 
 the article Mill-geering.’" About two-thirds the length 
 cf the bench from the cylinder, or roller, are two pins or stops 
 to hold a steel plate, which has a gradation of conical holes. 
 Through the largest of these holes, which is somewhat less 
 than the diameter of the circular piece of lead, the loop that 
 is screwed on to the end of the mandrel is passed, and attached 
 to a hook at the extremity of the chain, which chain is affixed 
 to the cylinder or roller. The cylinder being now thrown 
 into geer, the piece of lead is drawn through the hole in the 
 steel plate, which diminishes it in diameter, and increases it 
 in length ; and this operation is carried successively through 
 the series of gradually decreasing holes in the draw-plate, 
 until the pipe is reduced to the required diameter. The 
 cylinder is now struck out of geer^ and the mandrel liberated 
 from the chain, which is immediately attached to the other 
 end of it. The steel draw-plate being now removed, the 
 stops against which it rested allow the mandrel to pass be- 
 tween them, but detain the lead pipe, which, consequently, 
 by striking the cylinder into geer, allows the mandrel to be 
 extricated from it. A small portion of pipe being cut off at 
 both ends, the pipe is considered finished. Through the 
 whole of the operation, great care is taken to keep the 
 mandrel and steel plate well oiled. 
 
 As no acid can pass through lead pipe without becoming 
 more or less affected by its deleterious qualities, it is neces- 
 sary in cases where acids are used, to have pipes made of 
 iron, or of lead lined with tin. To line lead pipe with tin, 
 the lead pipe must be cast in a vertical mould, which has 
 a core of somewhat larger diameter than the intended-bore of 
 the pipe passing down its centre. When the pipe is cast, 
 and the metal is set, this mandrel is drawn out of the mould, 
 and another of smaller diameter is substituted. About as 
 much coarse resin as will lay on a shilling is now thrown into 
 the space between the pipe and the core or mandrel just 
 passed down the mould. This resin by the heat of the lead 
 
AND MACHINIST. 
 
 365 
 
 13 melted, and runs to the bottom of the mould. The melted 
 tin being now poured in, the resin will float on its surface, 
 and, consequently, as the tin rises, anoint the tin in every 
 part, and act as a flux, and unite the two vessels. As soon 
 as the tin is set, the last-mentioned mandrel is drawn out, 
 and the external mould being removed, the lead now lined 
 with tin is, when quite cold, ready to be submitted to the 
 process of drawing. Various other equally simple processes 
 are adapted to this purpose. 
 
 PAPER MANUFACTURE. 
 
 Paper, that highly valuable substance, which enables us 
 to communicate our thoughts to persons situate at the most 
 distant quarters of the civilized globe, is manufactured from 
 rags, by the aid of machinery. 
 
 It was formerly necessary to assort with great care the 
 rags which were intended to be manufactured into paper ; 
 and none but the whitest and best, and which, consequently, 
 were the most expensive, could be made into paper of the 
 finest quality ; but since the introduction of chlorine (which 
 was discovered by Scheele) into our bleaching establishments, 
 the necessity of this assortment has been greatly obviated ; 
 as it was soon conceived that that chemical agency, which 
 was capable of bleaching linen, was also applicable to the 
 whitening of the rag during the process of paper-making. 
 
 At that period of the process, when the rag is coining into 
 a state of pulp, chlorate of lime, which was first manufactured 
 by Mr. Tennant, of Glasgow, is introduced into the vat; and, 
 by its chemical action on the fibre, whitens or bleaches the 
 whole mass ; thus enabling the manufacturer to produce a 
 whiter and much finer quality of paper from rags of a se- 
 condary quality, than he had heretofore done from rags of 
 the most expensive description. It must, however, be ad- 
 mitted that, as in all bleaching processes where the fibre is 
 more or less deteriorated by the action of chlorine, the paper 
 manufactured and whitened by this agent is not so strong as 
 that formerly produced ; as may be observed in some thick 
 and beautifully white papers frequently offered to the public 
 
THE OPERATIVE MECHANIC 
 
 366 
 
 at aBtonisliing low prices, which are manufactured from 
 coloured and inferior rags, with a superabundance of the 
 chlorate of lime introduced in the process of the manufacture. 
 By this, therefore, it is evident that the chlorate of lime, 
 when used too abundantly, will rot or destroy the fibre of the 
 whole ; but when judiciously applied, it produces a paper of 
 superior colour, and of adequate strength for all practical 
 purposes. 
 
 The paper-mill consists of a water-wheel, or other first 
 mover, connected with a combination of toothed and other 
 wheels, so arranged as to cause the cylinder in the washer, 
 and the one in the beating engine, which will be hereafter 
 described, to make from 120 to 150 revolutions per minute. 
 On the same shaft, and of the same size as the water-wheel, 
 is a toothed or cogged wheel, which plays in a pinion ; the 
 spindle of this pinion is furnished with a crank, which, by 
 means of a connecting rod, gives a reciprocating motion to a 
 lever, for the purpose of working tw'o pumps, which raise 
 a constant stream of water from the mill-dam. This stream 
 of water is kept running through the rags in the washing- 
 engine, to carry away the dirt separated from them by the 
 operation. The structure of an engine is more minutely 
 explained by figs. 371, 3J2, 373, 374, &c. ; fig. 371 being 
 a section through the length of the engines, and fig. 372 
 a horizontal plan. 
 
 The large vat or cistern, A A, is of an oblong figure on the outside, the 
 angles being cut off ; but the inside, which is lined with lead, has straight 
 sides and circular ends. It is divided by a partition, B B, also covered 
 with lead. The cylinder C is fixed fast upon the spindle D, which extends 
 across the engine, and is put in motion, as before described, by the pinion E, 
 placed on the extremity of it. The cylinder is made of wood, and furnished 
 with a number of teeth, or cutters, fixed fast on its circumference, parallel 
 to the axis, and projecting about an inch, as is shown on a larger scale at 
 fig. 375. 
 
 Immediately beneath the cylinder, a block of wood, H, is placed, and 
 provided with similar cutters to those of the cylinder, which, when they 
 revolve, pass very near the teeth of the block, but do not touch ; the dis- 
 tance between them being capable of regulation, by elevating or depressing 
 the bearings on which the necks D,D, of the spindle are supported. These 
 bearings are made on two levers, F, F, which have tenons at their ends, 
 fitted into upright mortises, made in short beams, G, G, bolted to the sides 
 of the engine. (See also fig. 373.) The levers, F, F, are movable at one 
 end of each, the other ends being fitted to rise and fall on bolts, in the 
 beams G, as centres- 
 
 The front one of these levers, or that nearest to the cylinder C, is capable 
 of being elevated or depressed, by turning the handle of the screw b, 
 which, as shown in fig. 373, acts in a nut a, fixed to the tenon of F, and 
 comes up through the top of the beam G, upon which the head of the screw 
 
TAFER MAI^rFACTURE 
 
 11.50.51 &5Z 
 
 From 371 to 3 75 
 
 yeelf & Stcddey sc J5 X Str<and 
 
AND MACHINIST. 
 
 367 
 
 takes its bearing. Two brasses are let into the middle of the levers F, F 
 and form the bearings for the spindle of the engine to work upon. The 
 screw, h, is used to raise or lower the cylinder, and cause it to cut finer or 
 coarser, by enlarging or diminishing the space between the cutters in the 
 block, and those of the cylinder. 
 
 Near K, figs. 371 and 372, is a circular breasting made of boards, and 
 covered with sheet-lead : it is curved to fit the cylinder very truly, and 
 leaves but very little space between the teeth and breasting. An inclined 
 plane, K, leads regularly from the bottom of the engine-vat to the top of 
 this breasting ; and at the bottom of it the block, H, is fixed. 
 
 The engine is supplied with water by a pipe, Q, bringing it from the 
 pump ; this pipe delivers it into a small cistern, M, adjoining, and com- 
 municating with the engine. Tliq pipe has a cock, P, to stop the entrance 
 of the water, when required, or to regulate the quantity of its discharge. 
 The small cistern has a grating fixed across it, covered with a hair-strainer, 
 to catch any extraneous matter which may come in with the water, or a 
 flannel bag is sometimes tied over the orifice of the cock, P, through 
 which all the water must be filtered. When the engine is filled with water, 
 and a quantity of rags put in, they are, by the revolution of the cylinder, 
 drawn between its cutters and the teeth of the block H. This cuts them 
 in pieces, then, by the rapid motion of the cylinder, the rags and water are 
 thrown over the top of the breasting, upon the inclined plane ; in a short 
 time, this raises more rags and water into that part of the engine-vat ; and 
 the tendency to restore the equilibrium puts the whole contents of the vat 
 in slow motion, down the inclined plane K, and round the partition B B, 
 by which they come to the cylinder again in about the space of 20 minutes ; 
 so that the rags are repeatedly cut and chopped in every direction, till they 
 are reduced to a pulp. 
 
 This circulation is of advantage, in turning the rags over in the engine, 
 and causes them to present themselves to the cutters in a different direction 
 every time ; for as the cylinder cuts or clips in straight lines, in the same 
 manner as a pair of shears, it is requisite to cut the rags across in different 
 directions, to reduce them to a pulp. 
 
 Tlie manner of the cutting is this : the teeth of the block are placed 
 rather inclined to the axis of the cylinder, as shown by fig. 374, but the 
 teeth of the cylinder are parallel to its axis ; therefore, the cutting edges, 
 when they meet, are at a small angle, and come in contact first at one 
 end, and then successively the contacts proceed along to the other end, so 
 that any rags interspersed betw'een them are cut in the same manner as 
 they would be between the blades of a pair of shears. Sometimes the 
 plates or cutters, in the block, are bent to an angle in the middle, instead 
 of being straight, and inclined to the cylinder ; in this case, they are 
 called elbow plates, and of course the two ends are both inclined to the 
 axis of the cylinder in opposite directions. In either case, the edges of 
 the plate of the block cannot be straight lines, but must be curved, to 
 adapt themselves to the curve which a line traced on the cylinder will of 
 course have. 
 
 The plates or cutters of the block are united, by screwing them altogether, 
 and fitting them into a cavity cut out in the wooden block H ; their edges 
 are bevelled away on one side only; as shown at U in the section, fig. 374. 
 The block is fixed in its place by being made dove-tailed, and truly fitted 
 into the bottom of the cistern, so that the water will not leak by it. The 
 end of it comes through the wood-work of the chest, and projects a small 
 distance on the outside of it, being kept up to its place by a wedge, so that 
 by withdrawing this wedge, the block becomes loose, and can be removed, 
 
THE OPERATIVE MECHANIC 
 
 308 
 
 to sharpen the cn tiers, as occasion requires. This is done on a grindstone, 
 the plates being first separated from each other. 
 
 The cutters of the cylinder are fixed into grooves, cut in the wood of the 
 cylinder, at equal distances from each other round its circumference, in a 
 direction parallel to its axis ; the number of these grooves is twenty ; and 
 for the washer, each groove has two cutters or bars put into it; then a fillet 
 of wood is driven fast in between them, to hold them firm ; and the fillets 
 are kept fast by spikes driven into the solid wood of the cylinder. The 
 beater is made in the same manner, except that each groove contains three 
 bars and two fillets, as shown in fig. 375. 
 
 In the operation of the cylinder, it is necessary that it should be enclosed 
 in a case, or its great velocity would throw all the water and rags out of the 
 engine. The case is a wooden box, L L, enclosed on all sides except the 
 bottom ; one side of it rests upon the edge of the vat, and the other upon 
 the edge of the partition B B. The lines, c e, represent the edges of wooden 
 frames, which are covered with hair or wire-cloth ; and immediately behind 
 these, the box is made with a bottom, and a ledge towards the cylinder, 
 which makes a complete trough. 
 
 The dark spaces, e e, in fig. 371, show the situation of two openings, or 
 spouts, through the side of the case, which lead to flat lead-pipes, b, b, 
 fig. 372, which are placed by the side of the vat;' the beam, F, being cut 
 away for them. There are waste pipes, to convey away the foul water from 
 the engine ; for the cylinder, as it turns, throws a great quantity of water 
 and rags against the sieves ; the water goes through them, and runs down 
 into the trough at e e, and from thence into the ends of the lead pipes, 5, b, 
 fig. 372, by which it is conveyed away ; d^d, fig. 371, are grooves for two 
 boards, which, when put down in their places, cover the hair-sieves, and 
 stop the water from going through them, if it is required to retain the water 
 in the engine. This is always the case in the beating-engines, and therefore 
 they are seldom provided with these waste-pipes, or at most on one side 
 only ; the other side of the cover being curved, to conform to the cylinder. 
 Except this, the only difference between the washing-engine and the beater 
 is that the teeth of the latter are finer, having 60 instead of 40 bars on its 
 circumference ; and it revolves quicker than the washer, so that it will cut 
 and divide those particles which pass through the teeth of the washer. 
 
 The rags being now reduced to a state of pulp, we shall in 
 the next place proceed to show the method of forming it into 
 sheets of paper. 
 
 It was formerly the custom to allow a small, but sufficient 
 portion of the pulp to flow on a sieve furnished with two 
 handles, which sieve was agitated by a workman until the 
 pulp had subsided or settled regularly throughout the surface. 
 This, when it had passed through the usual processes of 
 pressing, drying, &c. constituted a sheet of paper; and its 
 texture was indicated by the fineness of the quality of the 
 wire out of wffiich the sieve was constructed. 
 
 This unmechanical and desultory mode of operation has 
 ])een obviated by improvements eflected by many ingenious 
 persons ; but the machines which are now almost universally 
 employed, and which have most decidedly superseded all 
 
AND MACHINIST. 
 
 3G9 
 
 Gtliel* attempts at the same object, was the invention of the 
 Messrs. Fourdrinier. The action and arrangement of this 
 ingenious piece of mechanism consists in having a horizontal 
 frame, of any required length, furnished with a roller or 
 cylinder at each end, over which is stretched an endless web 
 of brass wire, of the requisite texture or fineness for the 
 paper about to be manufactured. At one end of the frame, 
 parallel with, and immediately over, one of the cylinders, is a 
 long angular trough, into which the pulp is received, whence 
 it issues through a long slit or opening, which is regulated by 
 a screw, and falls on the surface of the web beneath. At this 
 period of the process, the cylinders are set in motion, and 
 the web proceeds slowly forward with a tremulous motion, 
 which arranges and disperses the pulp regularly over the 
 whole surface of the web. This tremulous motion is im^ 
 parted to the whole of the machinery by an eccentric move- 
 ment. 
 
 As soon as the paper arrives in this crude and wet state at 
 the extremity of the web of the further cylinder, it is wiped 
 and taken up by a larger cylinder, covered with felt or flannel, 
 and is passed between a series of similar cylinders, and finally 
 delivered to a reel, and wound off in a coil or hank so long as 
 the operation proceeds. Thus, paper, by the action of this 
 ingenious machine, may be manufactured to an unlimited 
 length, and of any width that is compatible with the manu- 
 facture of wire web. The reel or winder being now with- 
 drawn, the coil of paper is cut on both sides, forming sheets 
 of the length and breadth of the machine and reel on which it 
 is wound. 
 
 The arrangement of the different speeds of the various 
 cylinders for moving the web, and afterwards pressing the 
 paper, together with the action of the reel, and the tremulous 
 motion that is imparted to the whole of the machinery by the 
 eccentric or wiper, as also the regular supply of the pulp for 
 the various qualities of the paper to be manufactured, form a 
 most elegant combination of ingenuity and mechanical know- 
 ‘ ledge ; and it is only to be lamented that the inventors and 
 first proprietors, of this great source of national industry, 
 should not have obtained a reward adequate to the benefit 
 which they have conferred on their country. 
 
 The quantity of water which a paper-mill can command to 
 turn its engines, generally limits the extent of its trade; 
 hence the manufacturers should attend to every improvemeni 
 >f the machinery which can increase their effects 
 
 2 B 
 
I HE OPERATIVE MECHANiC 
 
 370 
 
 A very large and capital paper-mill^ at Maidstone^ in Kent^ 
 which is the principal seat of the paper trade in England^ is 
 worked by steam-engines, and is found to answer very well. 
 The machinery and building of a paper-mill should be well 
 made, and firmly put togetheiv otherw^e its great velocity 
 and power produces a tremor, which in time shakes every 
 thing to pieces. The noise and vibration of a washing- 
 engine is tremendous ; for when it revolves 120 times per 
 minute, and has forty teeth, each of which passes by twelve 
 or fourteen teeth in the block at every revolution, it will make 
 near 60,000 cuts per minute, and each of them sufficiently 
 loud to produce the most hon’ible growling sound which can 
 Be conceivedo 
 
 The beater revolving quicker, having si.7£ty teeth, and twenty 
 or twenty-four cutters in the block, will make 180,000 cut» 
 per minute, v/hich is so rapid, as to produce a coarse, musical 
 note or humming, which may be heard at a great distance from 
 the mill. This great number of cuts will account for an 
 engine being able, in the course of four or five hours’ workings 
 to reduce a quantity of rags lo those exceedingly minute 
 filaments, of which paper is composed. 
 
 Mr. John Dickenson took out a patent in 1809, for C^ertaiyit 
 improvements on his former patent machinery for cutting and 
 planing paper, as also for certain machinery for the manu- 
 facture of paper by a new method. His description of it is 
 as follows: 
 
 Tlie first part of the inverrtion, consisting in certain improvenients in the'" 
 patent machinery for cutting and planing paper, is described in the annexed 
 drawings ; wherein fig. 376 represents a sectional elevation, fig. 377 a 
 plan, and fig. 378 a transverse section. Every part in the elevation, fig. 376, 
 is on a line with the same part in the plan, fig. 377, and the same parts are 
 represented by the same letters in all the three figures ; a is a reel, covered 
 with paper; b a swinging roller, to draw the end of the paper a little back 
 after it has been cut ; c a bar, having a groove in its upper surface, into 
 which the circular cutter d runs. The bar c is movable up to a certain' 
 height, and connected with two arms, x x, by means of which it may he 
 moved downwards ; the springs e e will elevate it again when the pressure 
 is removed from the arms xx ; f is a sliding frame, having a pair of 
 tongs attached to the front of it, and marked g. The board on which the 
 paper is laid is marked h ; and on the side next the tongs is furnished 
 with thin teeth, ii. The frame which carries the tongs, slides in groove.s 
 in the frame of the machine, and is moved backwards and forwards by tlie 
 rod j, which in draiving the tongs from the reel of paper closes them ; and; 
 in forcing them back again towards the reel of paper, opens them. On 
 each side of the frame /is fixed a small roller, which act upon the arms xxy 
 so that the frame in being forced tow^ards the reel of paper presses the arm.s 
 down, and consequently moves the bar c down out of the way of the tongs?, 
 ■wdiichat that period are open. Tlie end of the paper is at that time lying 
 <;ven with the extremity of the teeth i and the jaws of thf^ tongs closing 
 
PAF'K >1^ MAF’r.'l^YXiT I'M 
 Troin 376 to 380 8c 384 to 386 
 
 n.53. 
 
 
 n 
 
 i 4 
 
 i ^ 
 
 i-i 
 
 I i r 
 

AND MACHINIST. 
 
 3/i 
 
 jTnmed lately that the rod j is put in motion to draw the frame back, seize 
 the paper in every interval between the teeth, and draw it along with them . 
 When they have carried it out the length that the sheet of paper is wanted, 
 the bar c having been raised up to its place by the springs ee, the circular 
 Cutter is thrown across, and as the edge descends into the groove about the 
 sixteenth part of an inch, the paper which is lying upon it is cut through, 
 and the ends fall down upon the heap below the tongs; being then forced 
 back, and at the same time opened by the rody, the other end of the sheet 
 is released, also the swinging roller b then falls dowm upon the board /^, 
 and draws back tlie end of the paper even wdth the line fofmed by the end 
 of the teetk, ready for being seized again by the tongs. The rods j, by 
 which the frame carrying the tongs is moved backwards and forwards, has 
 a hook A’, which can be fixed at any part of the rod by a screw ; and the 
 ciinck being furnished with pins m m, at two opposite points on its surface, 
 these catch the hooks, and draw the rod, and consequently the frame, with 
 the tongs outwards. When the ciinck has made half a revolution the hook 
 is stopped by the bar «, and the rod and frame remain stationary while 
 the paper is cut. When the pin has got clear of the hook, the rod and 
 frame are immediately drawn hack by aw'eight acting over a pulley, which 
 is connected wdth the rod by the cord o. Tire circular knife is fixed in a 
 sort of waggon, having four rollers p p, by means of w^hich it runs along llie 
 beams q q. The knife is kept moving at tlie rate of about five hundred turns 
 per minute, by means of a band passing round the stnall rigger r, and the 
 pulleys s Sy which is kept in motion by any convenient power. The waggoir 
 may be thrown across at the proper period by the following method, or any 
 other more convenient. A cord is attached to the waggon, acting over a 
 pulley with a weight at the end, sufficient to draw it across one way with 
 a quick motion : for drawing it across the other way a cord is attached to 
 the waggon, which is carried over a pulley, and fastened to the weight A, 
 in fig. 379, which is much heavier than the weight before mentioned. The 
 endless band B passes round the rigger D, which is kept in constant 
 uniform motion, according to the rate at which the paper is cut. The band 
 also passes round the rigger C, which has a click that stops it going round ; 
 consequently as the tigger goes on, it keeps winding up the w^eight A, and 
 the spare band is engrossed by the smaller weight E, so that when the click 
 that confines the rigger D is removed, the weight A descends and draw's it 
 round a complete revolution, when it is again caught by the click, at the 
 same time the weight A draws the waggon across, and it is caught on that 
 side the frame and confined by a click ; when the next sheet is to be cut the 
 waggon is released, and the weight attached to it on the other side draws it 
 across again, the heavier weight A being by that time drawn up high enough 
 to allow of its going all across ; the two clicks may be contrived according 
 to any common Well-known mechanical method, and the motion that 
 releases them can be communicated with the most advantage from the 
 click e ; the pins m m can be fixed in holes i f, at a greater or lesa distance 
 from the centre, according to the size the paper is intended to be Cut, and 
 the hook on the red j must be shifted accordingly. A regular motion may 
 be given to the click by any convenient power, and at such a rate as it is 
 required to cut the paper. 
 
 The remainder of the drawings is for the purpose of explaining the 
 remaining part of the invention, consisting of certain machines or machinery 
 for the manufacture of paper, by a new method. For this purpose, a 
 cylinder is constructed so as to possess the following requisites : in the first 
 place it must be hollow and open at the ends ; secondly, the surface of the 
 periphery must be like a sieve, with apertures communicating with the 
 
 2b2 
 
THE OPERATIVE MECHANIC 
 
 372 
 
 internal part large enough to permit the passage of water, but calculated idr 
 intercept fibres of rag ; thirdly, it must be so contrived that the surface will 
 not yield from its perfectly cylindrical form, notwithstanding a very consider- 
 able degree of pressure upon it ; fourthly, it must be furnished with broad 
 flat rings for the purpose of covering part of its surface ; at the ends there 
 may be several pairs of these rings of different widths, in order to vary the 
 proportion of the surface which is left uncovered, provided the same 
 cylinder is extended for making different sized papers ; fifthly, it must be 
 hung upon an axis in a horizorrtal position, and firmly fixed in bearings, so 
 that it may be turned by any convenient power ; sixthly, the numerous 
 small apertures on the external surface must open into a less number of 
 large ones, communicating with the internal surface, with solid interstices 
 between them; seventhly, it ought not to be made of wood because it 
 would be liable to warp, nor of iron because it would rust, and injure the 
 paper ; brass or any other strong metal w^ould be found most convenient. 
 To construct a cylinder possessing the requisites above-mentioned, of 
 v/hich the dimensions must be according to the size and thickness of tlie 
 paper it is intended for making, the patentee takes a brass cylinder, perfectly 
 smooth inside and outside, excepting a small portion at each end which is 
 left plain, and turns the outside so as to resemble a screw, the threads of 
 wdiich are about a quarter of an inch apart, and the twenty -fifth part of an 
 inch in depth, vv^ith a round edge. He then drills holes between the threads, 
 which are cut in a taper form, the diameter at top being the width of the 
 interval between the threads, and at the bottom reduced to one half that' 
 size ; the space on the outer surface of the cylinder, left between these 
 holes on each side, is equal to the breadth of the thread ; notches are cut in 
 the threads for the purpose of letting in cross wires, the diameter of which is 
 equal to that of the threads, so that w'hen they are laid into the notches and 
 soldered, or otherwise fastened down, the surface of the cylinder will resem- 
 ble network, with openings of an oblong shape, and having the surfaces 
 of all the interstices plane with each other, and wound to an equal curve. 
 It is then covered with an endless web of woven wire, which is drawn tight 
 over it. The ends of the cylinder are cut down, or rabbeted, so that a ring 
 may be m.ade to slide on each end ; and the ends of the wire are fastened to 
 this ring by means of small plates, which are put over the wire, and screwed 
 down upon the rings by means of screws which pass through tlie wire. 
 These rings are also furnished with other screws for the purpose of extend- 
 mg them out from the cylinder, and the wire being fastened to them it is 
 by that means stretched and drawn tight down upon the surface of tlie 
 cylinder. 
 
 In the annexed drawing, fig. 380, a to b represents a transverse section- 
 of a segment of the cylinder C C C, being the holes; ddd, the cross wire; 
 eece, the thread of the screw, which is shaded. 
 
 Fig. 381- is a plan of a portion of the external surface of the cylinder, 
 Vherein A to B shows it without the cross wires, or the external wove 
 wire ; C C C are the Jioles, e ee the thread of the screw with the notches 
 cut, a a a, for the reception of the cross wires ; B to C shows it with the 
 cross wires let in, d d d, which are soldered or otherwise fastened at their 
 ends into the ends of the cylinder. C to D shows it with the woven wire 
 laid over it, through which the surface of the cylinder is seen underneath. 
 
 Fig. 382 is a section of a part of the cylinder at one end, where the holes 
 are marked ccc, the cross wires ddd, the threads eee ; the external wove 
 wire/, is represented by a red line, it is carried under the plates g, and 
 fastened, by means of a number of screws, h, down upon the ring i, which 
 is shaded, and after it is fixed in that manner at each end of the cylinder. 
 
AND MACHINIST. 
 
 37s 
 
 tiie ring i may be extended from the cylinder by means of the larger screws 
 R, and the wire thereby strained down tight upon the surface of the cylinder; 
 this. part of the mechanism is also represented in the plan, fig. 381, where the 
 different parts are marked in the same manner, except that the woven wire 
 is drawn in black. 
 
 Fig. 383 is a representation of a connected w eb of laid wire, which may 
 be laid over the cylinder exactly in the same manner as the wove wire, 
 observing that the laid wires should be parallel with the axis, and the 
 tying wires eee at right angles with it, observing that the laid wires must 
 be very fine, placed very near together, and drawn as tight as possible at 
 the ends. The reason of laying the cross wires ddd diagonally, is prin- 
 cipally in order that they may not be parallel with the laid wires, in wdiich 
 case they would impede the passage of the water ; for this reason they ought 
 to lay at an angle as near 45 degrees as may be convenient ; but if the 
 cylinder is intended only for the manufacture of wove papers, the cross 
 wires may be parallel with the axis, the holes ranged in rows also parallel 
 with the axis, and the threads of the screw converted into small beads. - 
 There are other modes of constructing a cylinder possessing the necessary 
 requisites, but the patentee thought it expedient only to describe that 
 which he considers easiest of construction, most durable, and most effica- 
 cious in use. He also proposes connecting the rings mentioned as the 
 fourth requisite, as being necessary for covering part of the surface of the 
 cylinder, completed as above at the ends with arms, so as to form caps that 
 may be fixed on to the end of the cylinder, and each being furnished with 
 an axis, it can then be fixed in bearings for the purpose of being turned by 
 any convenient power. 
 
 Fig. 384 is an outline section, representing it in that situation, with a vessel 
 -fixed against it, which is called aback ; the sides or cheeks ofwhich are curved, 
 fo as to correspond with the rings or surface of the caps ; and the bottom, 
 at the point s, is made to close in upon the surface of the cylinder, so that 
 the vessel on all sides fits the cylinder in such manner, that, if fixed against 
 it, and filled with any fluid, the fluid would have no means whatever of 
 escaping, except by running through the surface of the cylinder, and out at 
 the ends : the exact shape of this vessel is not material. He next takes a 
 triangular trough, or receiver, closed up at the ends, and made so that the 
 i.pper edges fit the inside of the cylinder, and of such a depth that the 
 bottom may be about level wdth the centre of the cylinder, so that this 
 1 eing fixed, and the cylinder turned round, every part of the upper edge 
 may rub against the inside of the cylinder, which we have before said must 
 be perfectly smooth. In fig. 380 a section is shown of this trough, which has 
 an orifice at one end, at the bottom, marked jn. It may be observed, that 
 at the points n it comes in contact with the internal surface of the 
 cylinder. 
 
 Fig. 335 is an outline vertical section, wherein the trough is represented 
 fixed in the inside of the cylinder, and coloured blue, with the orifice ?n and 
 pipe communicating with it «. It is to be observed, that this trough is 
 firmly fixed by means of a plummer block 0 0 , which has the top coupling 
 screwed down fast, and the trough is supported at the other end by means 
 of a cylindrical pin, which works in a hole in the cap a. The other cap d, 
 instead of an axis, has a hole in the middle, fitted to the outside of the 
 pipe n, so that it forms a bearing for that side of the cylinder. The axis 
 of the cap «, at the other end of the cylinder, is supported in a bearing, 
 arid has upon it a cog-wheel p ; by means of which motion may be com- 
 municated to the cylinder, and as it turns round it rubs against the upper 
 edge of the trough, which will remain fixed, and receive any fluid that 
 
THE OPERATIVE MECHANIC 
 
 374 
 
 passes tlu'ou<;h the upper part of the surface of the cylinder, and carry it 
 off tlirough the oriftce m in the same section. The cylinder is coloured 
 yellow, the caps red, and the parts which answers to the rings are shaded, 
 
 hhg. 386 is a front view of one of the caps. 
 
 Fig, 387 is a sectional elevation of the machinery, in a state of prepara- 
 tion for the manufacture of paper. 
 
 Fig. 388 is a plan of the same. Each part in the elevation, fig, 387, is 
 on a line with the same part in the plan, fig. 388 ; and every part is marked 
 with the same letter in both. A is a circular stuff-chest; into which the 
 stuff is admitted from the engine. B is an agitator, consisting of a number 
 of arms, connected with the spindle C, which passes up through a tube D, 
 in the centre of the chest, and this being turned by the bevelled cog-wheel E, 
 keeps the stuff in motion in the chest, and also, by means of the two 
 riggers F F', gives motion to another small agitator, in the smaller vessel G, 
 wliich is for the purpose of receiving the stuff from the first chest, and it is 
 conveyed through the pipe FI, the aperture of which is enlarged or contracted 
 by means of a conical valve, which is acted upon by some apparatus I, on 
 the principle of a ball-cock, so that as the vessel fills wdth stuff it gradually 
 closes the orifice ; by this means the stuff in the smaller vessel G may be 
 kept at a uniform height, and the head being uniformly the same, the 
 discharge through the pipe J at the bottom will be always equal. The 
 large chest A may be of any shape or dimensions, and agitated in any 
 convenient manner ; the smaller chest G ought to be circular, and about 
 18 inches diameter, and the same depth. The use of it is to cause an 
 uniform discharge, which would not take place if the stuff were to pass from 
 the large chest without any intermediate vessel, because its passage through 
 the pipe would be more or less rapid, according to the height of the head, 
 which would be continually varying in proportion to the consumption or 
 accumulation of stuff. In the pipe J there is a cock K, by means of which 
 the quantity of stuff that is permitted to pass may be regulated with the 
 greatest degree of nicety ; and when it is once ascertained what proportion 
 of stuff is required, no variation in the supply can take place. The best 
 sort of cock or valve for the purpose will be such a one as leaves an open- 
 ing for the stufi‘, which is nearly round or square, because if it were narrow 
 the stuff might lodge. The pipe J descends into the pipe K, through which 
 there is a constant and rapid flow of water, and it carries awa.y the supply 
 of pulp from the pipe J, and they pass together into the vessel L, in which 
 there are two agitators M M, kept in pretty quick motion by means of the 
 riggers N N. In this vessel and in the pipe K the water and stuff become 
 intimately mixed, and formed into pulp, ofaproper consistency for working; 
 but it is to be olaserved, that in making paper by this method about four 
 times as much water should be introduced into the pulp as is made use of 
 in the ordinary modes of paper-making. From the vessel L the pulp flows 
 through the pipes O O into the vessel P, which has been before described 
 in fig. 384, and called a back. Q Q are waste pipes, for adjusting the height 
 of the head, or, in other words, the level of the pulp. In the back R is the 
 hollow cylinder, described in figs. 380, 381, 382, 383, 384, and 385, and 
 the cylinder being in motion in tlie direction described in the drawing, 
 the water is constantly flowing through the surface of it from the point S 
 to the point T, that is to say, through every part which is covered by the 
 pulp, and, as the water passes througli, tiie fibres of rag are left on the 
 surface, so that they are generally accumulating on any given part of the 
 surface of the cylinder during tlie whole of its passage from the point S to 
 the point T ; and w hen it emerges from the pulp at the point T, the 
 quantity requisite for the composition of a sheet of paper is collected, 
 
r.'KK 
 
 From SSI to 383 &• 3S7 to 392 
 381 390 
 
AND MACHINIST, 
 
 s.nd tills takes place in endless successkin as iong as the motion is 
 continued, and an unifoirn supply of pulp is kept up. It has been before 
 tftated, that when the surface of the cylinder emerges from the pulp 
 at the point T, the quantity of fibre requisite for the composition of a 
 sheet of paj:>er is collected; but at that period so much v'atcr is con- 
 tained among them, that it is necessary' to <iram off the greater part of it 
 before it will admit of any sort of pressure usually made use of for squeezing- 
 out the water, and for compressing the fibres of rag together, for the purpose 
 of making them cohere, and thereby giving tenacity to the paper. For this 
 purpose the trough V, the construction of which is more fully explained in 
 figs. 380 and 385, is fixed in the inside of the cylinder, and made to fit tight 
 all round its upper edge- It has a communication with the pipe W, as is 
 represented in fig. 385, where t]he pipe is pointed out by the letter n ; and 
 this pipe is connected with a pair of double-acting pumps X X, placed in a 
 cistern of water, so that when those pvunps are put in motion, tlie air con- 
 tained in the triangular space, enclosed between the trough and the cylinder, 
 is immediately drawn out, and consequently the pressure of the atmosjiherc 
 takes place upon the surface of the cylinder, which is covered with pulp, in 
 the state before described, and thereby rendered nearly impervious to tlie 
 air. The immediate affect produced is the squeezing out the water, and 
 laying the pulp down in a compact state on the surface of the cylinder, so 
 that the paper cannot be disturbed at tlie point Z, by the pressure of the 
 solid roller a. This part of the process I call the pneirmatic pressure. The 
 periphery of the roller « moves it exactly the same rate as the periphery of 
 the cylinder R, and in the direction described in the drawing. The roller 
 a is made to fit in exactly betwen the inside of the caps, described in fig. 385, 
 so that it shall only press upon the paper covering the surface of the pervious 
 cylinder. The surface of the roller A should be smooth, and the paper wilt 
 adhere to it instead of the pervious cylinder R, and be led round by it to 
 undergo a second pressure between the roller a and the roller b, which 
 iatter has a pervious surface, consequently the paper will be produced 
 sufficiently dry for leading off to the cutting. It is well known by paper- 
 makers, that, independent of the quality of the materials, the strength, 
 smoothness, and beauty of papers depend upon the arrangement of the 
 fibres of rag of wffiich it is composed ; that in a well-made sheet of paper 
 fhe fibres are ranged in a horizontal and parallel direction, and a manu- 
 facturer describing such a sheet of paper, would say that the stuff was well 
 shut, which quality all paper must possess in a greater or less degree, 
 because otherwise the parts of the sheet will scarcely cohere together, the 
 surface will be rough, the thickness uneven, and the paper devoid of 
 beauty, and not adapted for use. In the modes of paper-making exercised 
 hitherto, this indispensable object has been accomplished, by shaking the 
 mould or wire on which the pulp is settling, so that, as the water runs off, 
 the fibres are laid flat upon the surface of the mould, and arranged in a 
 parallel direction ; but in making paper by the machinery above described, 
 the stuff is perfectly well shut, without any shaking, the fibres of rag being- 
 deposited gradually, in a longitudinal direction, by means of the frictioa 
 which takes place upon the cylinder, in consequence of its motion being in 
 an opposite direction to that of the stream of pulp, the effect of which is to 
 smooth down the fibres of rag as they are laid upon the cylinder, and it is 
 necessarily continued during the whole time of the formation of the paper, 
 and must be uniform throughout every part of it. The reason of introducing 
 ,so large a quantity of water into the pulp, is in order that every fibre may 
 be afloat separately, and at liberty to take a direction according to th® 
 influence of these courses. 
 
THE OPERATIVE MECHANIC 
 
 376 
 
 It is to be observed, that the principle here developed would admit of other 
 less eligible modifications, such as confining a body of the pulp on the 
 surface of an endless well of woven wire, carried round cylinders, as in the 
 outline section, fig. 389, or supporting it on a cylinder of a large size, as in 
 the outline section, fig. 390, without applying the pneumatic pressure in 
 either case. 
 
 In fig. 389 the cylinder ab c should be hollow, and have pervious surfaces. 
 
 In fig. 390 the cylinder might be of a more simple construction than that 
 described in figs. 380, 381, 382, 384, and 385, but unless of a very large 
 size indeed, it could only be made use of for making very thin papers, be^ 
 cause the water requires so long time to run off before the paper will admit 
 of any mechanical pressure. 
 
 It is to be observed, that in making paper by this method, after a certain 
 quantity of fibres of rag are deposited on the surface of the cylinder, it ren- 
 ders the passage of the water and the accumulation of more fibres so diffi- 
 cult, that without a considerable height of pulp the pressure will not be 
 sufficient to force the water through the cylinder, and the fibres of rag laying 
 upon it, the consequence of which w^ould be, that the fibres of rag accumu- 
 lated on the surface of the cylinder would be washed off by the pulp, or very 
 much disturbed before they arrived at the point T, which is the level of the 
 pulp in the back ; to obviate this, it will be necessary to add the pressure of 
 the atmosphere to the weight of the water in making thick papers, which 
 may be done by extending one side of the trough V below the level of the 
 pulp, so as to cause a suction under that part of the cylinder which is 
 covered by the pulp, as well as under that part which has emerged from it. 
 For this purpose a wider trough would be necessary ; but at all events the 
 exact proportion of the cylinder, covered by the trough, is not material, be- 
 cause it will be found by experience what width is sufficient for drying the 
 paper, so as to enable it to have the pressure of the roller a. The roller a 
 ought to press on the cylinder R about the point which is ovei one side of 
 the trough V, and, according as the trough is shifted, the roller should be 
 shifted also ; but this pressure ought to be not less than forty-five degrees 
 above the level of the axis, because, otherwise, part of the water pressed 
 out of the paper will be absorbed by it again, whereas, from the position it 
 acts in, in the drawing, fig. 387, the water will be sucked into the trough. 
 The roller a should not be fixed in bearings, but confined down upon the 
 cylinder by weights, suspended upon each end of the axis, which may be 
 adjusted according to circumstances, and in all cases the principal pressure 
 should be upon the roller b. The water which runs through the cylinder in 
 figs. 387 and 388, and out at the end, falls in the first instance into the cis- 
 tern C, from whence it passes through the pipe d into the cistern e, and 
 from thence is, by means of a pair of double-acting pumps,/ / forced through 
 the pipe K into the vessel L, so that it continually returns for the same purpose 
 of conducting the pulp to the cylinder from the pipe J. The pipe G is a sort 
 of gauge, by means of which, after the pulp rises to a proper height in the 
 vessel L, the remainder of the water is carried off into the cistern C, where 
 there may be a waste pipe for conveying off the superfluous quantity. Thq 
 water drawn from the cylinder R, through the trough V, by means of the 
 air and water pumps X X, may run to waste. The size of the cylinder R, 
 and of the trough V, must be regulated according to the substance and di- 
 mensions of the paper it is intended for making. Fifteen inches will be 
 sufficient for the diameter of a cylinder intended for making paper equal in 
 substance to a paper twenty-two inches by seventeen inches and a half, 
 weighing twenty pounds per ream : the length of the cylinder is entirely 
 arbitrary. The thickness of the paper made by a cylinder may be adjusted 
 
AND MACHINIST, 
 
 377 
 
 jn various ways : first, by using cylinders of various diameters ; secondly, by 
 accelerating or retarding the motion of the cylinder ; thirdly, by varying the 
 proportion of the surface of the cylinder, which is covered with pulp; 
 fourthly, by varying the consistency of the pulp. The periphery of the cylin- 
 der ought to move at the rate of about thirty-six feet per minute ; the pulp 
 ought at all events to be very thin, and therefore the most eligible mode 
 of adjusting the thickness of the paper would be by varying the pro- 
 portion of the surface of the cylinder, which is covered w'ith pulp ; conse- 
 quently for thicker papers a larger cylinder would be necessary, or a back 
 may be made use of, extending higher up towards the point Z, so as to covet 
 a larger proportion of the surface of the same cylinder : and for thinner pa- 
 per a back might be made use of covering less of the cylinder, as in fig. 390, 
 by means of the cock in pipe J. The quantity of pulp supplied to the cylin- 
 der can be adjusted with the greatest accuracy, consequently the thickness 
 of the paper may be preserved uniform, or varied at discretion, provided the 
 thickness of the pulp in the chest A, and the motion of the cylinder R be 
 continued uniform. By means of the gauge pipes Q the level of the pulp in 
 the back P can be varied till the most eligible point for the cylinder to emerge 
 from the pulp is ascertained, and the supply of water through the pipe r 
 must be adjusted accordingly. It may be laid down as a general rule, that 
 the thicker the paper the higher should be the level of the pulp in the back. 
 In order to close the trough V tight upon the cylinder R, the patentee pro- 
 poses packing it all round the top, where it comes in contact withinside of 
 the cylinder, as at the points nn, in the section fig. 380. 
 
 The mode of packing is so well known, that it is unnecessary to give any 
 description, except the representation in the drawing. The friction of the 
 oack P upon the cylinder may be taken off by strips of woollen cloth or 
 leather, particularly at the line across from the point S. 
 
 Figs. 391 and 392 are for the purpose of explaining a more simple mode 
 of construction. A is a hollow cylinder, with a pervious surface, which may 
 be used in cases when the pneumatic pressure is not applied ; «« a is the 
 thread of a screw ; bb represent cross-bars, carried across ^he internal 
 surface, parallel with the axis. The best mode of constructing it will be to 
 cast a cylinder with the bars in the inside, and to cut the screw deep enough 
 to form an opening between every bar. It should be furnished with cross 
 wires, c c e, and covered with wove wire, in the same way as the cylinder 
 R. It might be made on a larger or smaller scale, according to the purpose 
 for which it is required. The roller b, in figs. 387 and 388, may be made 
 in this manner, but stronger, as a great degree of pressure is intended to 
 take place upon it. 
 
 When the machinery is to work, the agitator and pumps should be set in 
 motion ; first by turning the shaft K, and then the cylinder R, by means of 
 the cog-wheel P, which gives motion to the rollers a and b, by cog-wheels q 
 and r. The mode of giving motion, and the situation of the pumps and 
 stuff-chest, may be arranged according to convenience, but the motion 
 pught to be perfectly regular. 
 
THK OPERATIVE MECHANIC 
 
 378 
 
 COTTON MANUFACTURE. 
 
 Cotton is a fibrous vegetable substance, the produce of a 
 small tree called the gossypium, or cotton plant, which grows 
 naturally, and is much cultivated, in the tropical regions of 
 Asia, Africa, and America. 
 
 The cotton, when collected from the pod, contains the seed, 
 and pieces of the husk by which it was enveloped is attached 
 to it ; it has therefore, preparatory to being subjected to the 
 operation of spinning, to undergo a process that will divest it 
 of these superfluous parts. The ancient mode of effecting 
 this w”is by what is termed bowing it ; that is, exposing it to 
 the action of a bow, about four feet long, such as is used at 
 the present day by hatters. The process consisted merely in 
 placing the cotton upon a square table with horizontal chinks 
 cut through it, and submitting it to the repeated action of the 
 bow until the dust, seeds, and superfluous parts had separated 
 and fallen through the chinks. This inconvenient and desul- 
 tory mode has in modern times been superseded by a far more 
 eftectual and expeditious one, by the application of a machine 
 called a gm. Gins are of two kinds, the one called the roller- 
 gin ; the other the saw-gin. 
 
 The roller-gin is represented in fig. 399. It consists of two shallow fluted 
 rollers a and b, placed so near to each other, that when the cotton is thrust 
 against the line where they enter into contact, they immediately seize hold of 
 it and draw it in between them, while the seeds and other particles, not 
 being able to pass through, fall into the box K, and are, by the slanting di- 
 rection of its bottom, delivered on one side. The motion is communicated 
 by means of the treadle and crank C D, and is equalized by the fly-wheel 
 
 E. The cotton is presented to the rollers over the board f g, and is drawn 
 between them, and delivered at I H. In South America this kind of gin 
 is much used, and a negro working with one of them can clean from 30 lbs. 
 to 40 lbs, weight of cotton per day, which, however, is considered heavy 
 work. 
 
 The saw-gin is given in section in fig. 400. The cotton is thrown into the 
 receptacle A B, on that side marked C D, which is formed of strong wires 
 placed parallel to each other, to admit the circular saws E, fixed on the axis 
 
 F, behind the grating, about an eighth of an inch apart, to pass between 
 them. By this means, the teeth of the saws seize hold of the cotton and draw 
 it through the bars ; and the seeds and other superfluous parts, being too 
 bulky to pass tiirough, remain behind, and eventually fall through the aper- 
 ture G. The cotton is brushed from the saws by a circular brush H, made 
 to revolve rapidly on its axis. The motion is communicated by manual or 
 any other power applied to the axis F, upon one end of which is the wheel 
 K, acting in the pinion M, fixed to one end of the axis of the brush. 
 
 The application of the power of horses to either the roller, 
 or saw-gin, would greatly aid the process, which, as we be - 
 fore have stated, is considered heavy work for the negroes, 
 
AND MACHINIST. 
 
 r>79 
 
 and on that account is much avoided. An objection has been 
 started to the applying of this power, under a supposition, 
 that the animal by changing his speed would injure the cotton ; 
 it is almost superfluous to add that many simple contrivances 
 may be adapted to equalize the motion, and prevent these 
 dreaded effects. 
 
 When the cotton has undergone either of these processes, 
 it is packed, and exported to the European markets. 
 
 When it arrives in this country, it is again submitted to the 
 action of machinery for the further separation of the extra- 
 neous matter, unless it is to be spun into coarse yam, when 
 the preceding process is considered sufficient. 
 
 The first machine that we shall describe as used in this country for the fur- 
 ther clearing of the particles is called a picker, and is represented in fig. 393. 
 A and B are two rollers, having an endless-cloth, C D, stretched over them. 
 This cloth is called the feeding-cloth, and its upper surface is, by the revolu- 
 tion of the rollers, always carried towards D. E and F are two fluted rollers, 
 which nearly touch each other, and revolve, so that their touching surfaces 
 pass towards G H. G H I K are cylinders, covered on their outer surfaces 
 with long blunt pins, making about 250 revolutions, in the direction of the 
 letters, per minute. L L is a grating of wires for the seeds to fall through, 
 when the cotton carried by the feeding-cloth is delivered by the small rollers 
 upon the face of G H. By the rapid revolution of G H, the cotton is thrown 
 against the top O P, and is carried forwa,rd and delivered upon the cylinder 
 I K, which in like manner carries it rapidly round, draws it over the grating, 
 and delivers it back upon the lower face of G II, which after having drawn 
 it over the remainder of the grating, and divested it of the remainder of the 
 seeds and particles of dust, deposits it in the box R R. 
 
 This machine is liable to injure the staple of the cotton, and is therefore 
 superseded by another called a hatter, represented in fig. 401. In this ma- 
 chine, the feeding-cloth upon the rollers A and B carries forward the cotton 
 to the rollers c and cl, w'hich deliver it upon the curved rack or grating d e, 
 while a scotcher, g h, revolving rapidly upon its axis, strikes the cotton with 
 its two edges g and h, and divides it ; at the same time a draught of air, 
 created by the revolution of the fan I, blows the cotton forward over the 
 grating K K, divests it of the superfluous parts, and ultimately deposits 
 it in a box at the end. 
 
 The cotton is now considered in a state fit for the operation 
 of spinning; which is differently performed according to the 
 purposes to which the yarn is to be applied. The different 
 sorts of spinning may be classed under the respective heads of 
 Jenny, mule, and water spinning. 
 
 Mule-spmning, which is by far the most perfect process, 
 and by which the finest }^arn is produced, shall first have our 
 attention. 
 
 In this process, when the finest yarn is to be produced, the 
 cotton, instead of being submitted to the operation of either 
 of the machines before described, is cleansed entirely by the 
 hand. The mode of effecting this is, by spreading the cotton 
 
THE OPERATIVE MECHANIC 
 
 380 
 
 upon a strong netting of cords stretched on a frame, and beat- 
 ing it with osier wands till divested of its impurities. It then 
 undergoes the elementary operations of carding, drawing, 
 stretching and plying, and twisting ; the whole of which are 
 essential in the manufacture of mule yarn. 
 
 Carding is performed by two kinds of engines, one of which, 
 called the breaker, operates upon the cotton preparatory to its 
 being submitted to the operation of the other, called the 
 finisher. 
 
 A card is a kind of brush, formed by making wires into the form of 
 staples, as represented in fig. 394. Tire two legs of the staples are placed 
 through holes in a flexible piece of leather, and present to the side view a 
 form similar to that shown in the figure, where A B is the leather, and C D 
 the wires forced through it. Cards are formed in two ways ; the one called 
 sheet-card, is made about four inches wide, and 18 inches long, or of a 
 length corresponding with the width of the main cylinder, which they have 
 to cover ; the other, called fillet-card, is made in one continuous band or 
 fillet, and is used for covering the doffer cylinder. The teeth of the fillet-card 
 are placed pointing in the direction of the length of the fillet, and completely 
 cover the cylinder to which they are applied ; whereas in sheet-cards a space 
 is left between every sheet, as may be seen on the main cylinder, fig. 395. 
 
 Fig. 395 represents a sectional view of the immediate working parts of a 
 breaker carding-engine. A is the main cylinder, covered with sheet-cards ; 
 B the doffer cylinder, covered with fillet-card ; C C C are the tops ; e is the 
 feeding-cloth supplied with cotton, which has been previously weighed, 
 moving forward over the roller,/, by means of the roller apd delivering 
 the cotton between the feeding-rollers H H, which carry it to the main cy- 
 linder. The main cylinder revolves rapidly in the direction of the dart, and 
 carries the cotton upward between itself and the tops, which are covered 
 with sheet-cards, about inches to 2 inches wide, so that they may, as 
 nearly as possible, follow the curve of the main cylinder. I is the lapping- 
 cylinder, having a wooden roller laying upon its upper surface ; and K 
 is the doffer or taker-off, having affixed to it the steel comb called the 
 doffing-plate. 
 
 The doffing-plate may be seen more at large in fig. 396, which represents 
 a front view of the doffer cylinder on a larger scale. On inspecting tins 
 figure, it will be seen, that the doffing-plate L L, whose lower edge is 
 formed like a comb, is fastened across the whole of the doffer cylinder, arid 
 is supported by the two uprights m m, fastened on two cranks on the shaft 
 
 71-. The upper parts of these uprights, m m, are fastened to corresponding 
 cranks at n n, so that the doffing-plate, by the revolution of the shaft, is 
 made to move downwards while in contact with the doffer cylinder, and up- 
 wards while away from it. The cotton is taken in by the feeding rollers, 
 and is carried up by the main cylinder and passed between it and the tops 
 or flats, whose teeth lie in an opposite direction to those of the main 
 cylinder, and by whose united action the cotton is combed, divided, and 
 cleansed, and its fibres placed in a direction nxore parallel to each other. 
 
 The main cylinder, by its revolving motion, is soon covered 
 with cotton, and is divested of it by the doffer cylinder, which 
 is placed so as nearly to touch it, and which moves at a much 
 slower speed, in the direction of the dart. The effect of this 
 engine would therefore be to distribute the cotton equally over 
 
(COTT QN MAHITFAC TURM 
 Front 393to3f)8 
 3SS , ' 
 
 FI 35 
 
i 
 
 js 
 
 1 
 
 
 \ 
 
AND MACHINIST. 
 
 381 
 
 the main cylinder, the top cards, and the doffer cylinder 5 but 
 the doffing-plate, bj^the action already described, is continually 
 clearing the doffer cylinder ; whose points are consequently 
 left bare to receive a fresh supply from the main cylinder. 
 The doffing-plate continually strips the doffer cylinder of the 
 carded cotton, which it delivers upon the lapping cylinder in 
 one continuous web of about 18 inches wide, which is the usual 
 width of the engines for fine work. 
 
 When the top cards are covered with cotton, an attendant 
 is appointed to take them off and to divest them of the cotton 
 by means of a card nailed on a board, which he carries in his 
 hand for that purpose. 
 
 The quantity of work delivered to the engine is ruled by the 
 speed of the cylinders and quality of the cotton. When it has 
 passed through the engine, and is wound upon the lapping 
 cylinder, (which is so adjusted as to contain about 20 laps,) 
 the attendant lifts up the roller F, makes a division in the 
 circular web, and takes it off the roller. 
 
 In this operation we are presented with the first act of ply- 
 ing or doubling, which is introduced in the process of spin- 
 ning in order to obtain equality in the strength and thickness 
 of the yarn. 
 
 The cotton is in this state called a lap, and is immediately taken to a 
 finisher-engine, which, in general, is disposed back to front, immediately after 
 the breaker-engine, as may be seen in fig. 397. The construction of the 
 finisher-engine is exactly similar to that of the breaker-engine, except that 
 instead of having a lapping cylinder, the cotton, when it leaves the doffer, is 
 drawn through a mouth-piece, 11, formed like the end of a trumpet, by means 
 of the rollers ^ and t, and is delivered into the can W. The rollers s and t 
 may be seen in section in this figure, and in a front view in fig. 396. Pre- 
 viously, however, to leaving this process, we shall make a few remarks, as 
 it is, with much propriety, considered the very foundation of all good 
 spinning. 
 
 The breaker-engine for spinning fine cotton is generally 
 covered with cards of a fineness that will admit 225 teeth, or 
 450 points, in a square inch ; and the finisher 2J5, or 550. 
 But spinners are much divided on this subject, and in some 
 mills the same work is performed with cards one- fifth coarser 
 than it is in others. The top cards are in general one-tenth 
 coarser, and those of the doffer cylinder one-tenth finer, than 
 those on the main cylinder : and in some manufactories, at the 
 back part of the engines, where the cotton first arrives, coarser 
 top cards have been introduced, with a view of divesting the 
 cotton of the largest particles of extraneous matter, and in 
 some instances have been again laid aside as superfluous. 
 Cards must he set easy in the leather, which should be thin 
 and strong. The card-engine is driven by a strap passing 
 
THE OPERATIVE MECHANIC 
 
 from a drum over a fast and loose pulley, fixed on the shaft 
 of the main cylinder. The fast and loose pulley is represented 
 in fig. 65 ; and its utility has been explained in the article 
 Mill-geering. 
 
 To return to the manufacture, the cotton, which is now in the can from 
 the card-engines, in the form of a sliver, is next submitted to the process of 
 drawing, represented in hg. 398. In this })rocess three or four card-ends 
 are brought in tin cans, and passed between the rollers A B and C D, which 
 revolve with different velocities ; that is, the rollers C and D revol'vc much 
 quicker than A and B, and the top rollers A and C are made to press upon 
 B and D by means of the v/eight e. Now, supposing four slivers be placed 
 together, and passed throtigh the rollers A B and C D, and that C D revolve 
 so much quicker than A B, that the sliver will become four times its original 
 length, the cotton will, by such elongation, be reduced in thickness three- 
 fourths, that is, to the same thickness of a single sliver when first brought to 
 the rollers. By this process the fibres of the cotton are laid more parallel 
 to each other, in the direction of the length of the sliver, and tlie operation 
 is repeated, by plying the slivers which have passed the rollers, and passing 
 them through a similar set. The sliver, when thus plied and reduced, is 
 drawn through the mouth-piece G, by the rollers E and F, and delivered 
 into another can. 
 
 After the cotton has been plied and drawn as many times 
 as the spinner, from the quality of the cotton, rmd the intended 
 quality of the j^arn, considers necessary, it is carried to the 
 Toving-frame. 
 
 The roving-frame^ which is much used in mills vdiere mule-spinning is 
 carried on, is represented in fig. 402, and is termed the can roving-frame. 
 A B, two rollers, moving at a slower speed than C D ; A and C are pressed 
 upon the rollers B and D by the weight E, as may be seen in a front view, 
 fig. 402, and section, fig. 403. The cans (fig. 402) are represented, the one 
 shut, and the other open ; the latter opens by means of hinges, after raising 
 the ring g. The cans are capable of revolving upon their spindles h h, and 
 are supported in an upright position by the collars i i, aud have at their 
 upper extremities funnel-shaped pieces, k k. 
 
 If ttvo slivers of cotton are brought from the drawing-frame, and passed 
 between the rollers A B and C D, the processes of plying and drawing will 
 again take place ; and the rollers C D will feed the end thus formed into the 
 can through the mouth-piece at k, which, by revolving rapidly upon its 
 axis, will impart to the end, or sliver, a slight degree of twist. When the 
 can is filled, the rollers are thrown out of geer, and the motion ceases ; the 
 can is then opened, and the cotton, or as it is now called, the roving, i& 
 taken out and wound upon a bobbin, and in that state is carried to a machine 
 called a stretcher. 
 
 Some objections exist against this species of roving ; firsts 
 from the necessity of taking the roving out of the can for the 
 purpose of windiug it upon a bobbin, during which it is liable 
 to sustain much damage from the fibres being in a very slight 
 state of adhesion ; and secondly^ from the roving receiving its 
 tvdst solely from the revolution of the can in which it rests, 
 and by which the twist is not equally diffused over the whole 
 length of the roving. The first objection was attempted U> 
 
404 
 
 R.56 
 
 V- 
 
 C (0 T T OK 3HAKCT A (C TJ7MIE 
 
 402 
 
 I 
 
AND MACHINIST. 
 
 38:J 
 
 be obviated, by placing the can in a frame, and drawing the 
 roving out through the mouth-piece at which it entered ; and 
 a remedy for the second was somewhat unsuccessfully at- 
 tempted by Mr. Arkwright^ who tried to introduce a pair of 
 rollers upon the top of the roving-can, to seize hold and feed 
 the roving into the can as fast as it was received from the 
 drawing-rollers. This, undoubtedly, would have perfectly 
 equalized the twist throughout > but the machinery necessary 
 to produce the double rotatory motion was found to be incon- 
 venient, and the plan was in consequence abandoned. 
 
 A roving-frame of a different construction^ which obviates the preceding 
 objections, and which, in consequence, has received more general adoption, 
 is represented in fig. 404 ; it is called the bobbin and filer roving-frame. 
 The rollers for stretching are similar to those before described ; and the plied 
 and drawn roving is represented as coming from the rollers at A, whence it 
 passes through an eye at C, over the top of the spindle D, and down one of 
 the legs of the flier B B, which is for that purpose formed tubular. By the 
 revolution of the spindle D, generated by a strap acting upon the pulley F, 
 the fliers are carried swiftly round, and twist and deliver the thread upon 
 the bobbin E, wbicli is moved upwards upon the spindle by raising the 
 board G G, upon which it rests, descending again as the board descends. 
 
 The roving is, by this means, slightly twisted and wound upon a bobbin, 
 in a fit stale to be immediately carried to the stretching-frame, which, being 
 very similar in its construction to the mule, we consider it necessary only to 
 give a side view of one of the spindles of a mule, shown in fig. 405. A is 
 the place where the bobbin from the roving-frame (not shown in this figure) 
 would have been situate ; and c c c are three pairs of rollers, revolving at 
 different speeds, for the further drawing of the roving. The roving, when it 
 has been thus drawn, is brought to the spindle B, which is formed of 
 polished steel, ground slightly tapering to the end, which is a round blunt 
 point. The spindle receives its motion at the pulley D, by means of a band 
 passing round a drum in the box E E E ; which drum has bands passing 
 in the same manner to several other spindles. When the motion com- 
 mences, the carriage E E E passes backwards to the position shown by the 
 dotted lines, and carries with it the spindles to the position B^ ; during 
 which the spindle revolves rapidly on its axis, and gives a certain degree of 
 twist to the roving, which already has undergone a reduction in diameter 
 by passing through the rollers C C C. The extent to which the frame re- 
 cedes is about three yards, and when the spindles have given the requisite 
 degree of twist to the yarn, it returns to its former place ; while the at- 
 tendant, by moving the bar II upon its axis, presses the yarn downwards, 
 by means of a piece of wire K, which causes it to be wound upon the spin- 
 dles, so as to form a figure that may be represented by two cones, one 
 having a more acute angle than the other, placed base to base, as shown at 
 A, B, and Bh This form is termed a cop, and the act of so distributing 
 the yarn, by the movement of II K, the building of the cop. 
 
 It may here be observed, that although this is called the 
 stretching-frame, the yarn is not stretched, but merely under- 
 goes a further process of drawing and spinning, and that the 
 stretching is not performed till in the next operation, which 
 is performed upon the mule^ and termed spinning. 
 
384 
 
 THE OPERATIVE MECHANIC 
 
 The yarn, delivered from the stretching-frame in the form 
 of a cop, is taken to the mule, which is, though much lighter, 
 both in the form and action of the parts, very similar to the 
 stretching-frame. The spindles also are of a smaller size, 
 and are situated nearer to each other. 
 
 The mule sjnnning-frame differs from that of the stretching- 
 frame insomuch as the act of stretching is added to the other 
 operations ; for when the frame E E E has receded a certain 
 distance, generally about one yard, the rollers C C C cease to 
 move, and the frame still continuing to recede, stretches the 
 yarn. During this process, the spindles on the frame E E E 
 move considerably quicker, in order to save time. The 
 stretching is performed with a view to elongate and reduce 
 those places in the yarn which have a greater diameter, and 
 are less twisted than the other parts, so that the size and 
 twist of the yarn may be more uniform throughout. When 
 the cops are full, they are taken from the moving spindles, 
 and placed on stationary parts of other mules, as at A, and 
 the yarn is again submitted to the same process, until it is 
 reduced and spun to the proper fineness, both as respects the 
 diameter and the twist ; during the whole of which process, 
 the yarn can be continually joined, so that the cops, which 
 are in separate pieces, can be added to each other in parts, or 
 otherwise, as the continual elongation of the yarn in the 
 course of the different operations of each mule may require. 
 The pieces are joined by children, called piecers, who are in 
 attendance on each mule, to join any yam that maybe broken 
 in the act of stretching or twisting. 
 
 The drums, which drive the spindles in those parts of the 
 mule that recede, receive their motions from bands com- 
 municating with the moving power ; but the advancement 
 and recession of the carriage, for the purposes of receiving 
 and stretching the yarn, as before described, is performed by 
 means of a wheel moved by hand-labour. A spinner is enabled 
 by experience to judge of and regulate both these operations, 
 as also the building of the cop, which is a matter of very 
 great nicety ; for if the cop is not well built, the yarn will 
 not run off even when it is to be used. The number of spin- 
 dles on a mule amount frequently to 300. The yarn produced 
 l)y mule-spinning, being by far the most perfect, is employed 
 in the fabrication of the finest articles, such as lace and 
 hosiery ; and when it is twisted in two, four, or six plies, is 
 used for sewing-thread. 
 
 Jenny -spinning is of earlier date, and a much less perfect 
 process than mule-spinning; consequently it is but little 
 
And machinist. 
 
 3a5 
 
 Used, except in the manufacture of yam for coarse goods. In 
 this spinning, the cotton, after having been cleansed by some 
 of the processes already described, is, preparatory to being 
 exposed to the action of the jenny, immersed in a solution of 
 soap and Avater, to divest it of the glutinous matter generally 
 found on the surface of this and other vegetable fibres ; it is 
 then, after the soap and water has been pressed from it, put 
 into a warm stove, and when dry, is considered to be in a fit 
 state to be exposed to the operation of the cardiiig-engine. 
 
 The carding-engine used in jenny-spinning is different in 
 its construction to the one before described ; for in mule and 
 water spinning there is a breaker and a finisher engine ; but 
 the engine used in this process is called the double-engine ; 
 the first part, or breaker, is in the same frame with the second 
 part, or finisher, and the doffer from the first part delivers the 
 cotton upon the main cylinder of the second part, wliich, in 
 like manner, delivers it upon the second dofier. The second 
 defter, instead of being covered v/ith fillet-cards, as the doffer 
 of the single engines, is covered with sheet-cards, like the 
 main cylinder, but being of smaller dimensions, has generally 
 only twelve cards upon it 5 therefore the web of cotton combed 
 from such doffer by the doffing-plate is not in one continuous 
 piece, but in several pieces or portions, equal to the quantity 
 attached to each sheet-card upon the doffing- C 5 dinder. 
 
 As the several small portions are delivered by the comb, 
 they fall into the concave part of a smooth arc that is equal 
 to one-third of a circle. In this arc a cylinder of smooth 
 mahogany slowly revolves in such direction that the lower 
 Surface in the arc passes from the engine. This cylinder has 
 small cavities or flutes on its surface, in a parallel direction 
 to its axis ; the angles on the projections between the flutes 
 are taken off, so that the several portions of web which fall 
 from the doffer into the arc are seized by the flutes, and car- 
 ried forward on the concave face of the arc, and formed into 
 a sliver, about half an inch in diameter, and of a length cor- 
 responding with the breadth of the carding-engines, wdiich is 
 about from 24 to 34 inches. The portions thus rolled are 
 called rows, rolls, or rowans. 
 
 ' In this state, the cotton may be considered in the same 
 relative state of progress as a card-end in mule or water 
 spinning ; but it is evident that this mode of spinning is very 
 deficient for the purposes of fine yarn, insomuch as in the 
 rowans the fibres of the cotton are laid across the longitudinal 
 direction in which they are to be spun, so that the advantage 
 derived in the other process of carding, from the fibres being 
 
380 
 
 THE OPERATIVE MECHANIC 
 
 placed in a direction parallel to the intended length of the 
 yarn^ is entirely lost. In this process^ also, the advantage of 
 plying, which we have noticed as taking place on the lapping 
 cylinder, is omitted. 
 
 When the rowans are perfected by the mahogany cylindery 
 they are taken up by children, and placed upon the feeding- 
 cloth of a machine called the billy, or roving-billy, the 
 operation of which is called roving or slubbing ; but the latter 
 expression is now but seldom used, except in the manufacture 
 of woollen. This machine is in its construction and action 
 very similar to the mule, as is the feeding-cloth to that de- 
 scribed in the machine called the picker and batter. 
 
 The feeding-cloth lays in a slanting position, and the 
 rowans are placed upon it so that they can pass lengthv/ise 
 in the direction of its action, and be delivered over the upper 
 roller between two pieces of board which possess a capability 
 of clasping and again relieving them. The rowans are then 
 attached to revolving spindles,, which have an advancing and 
 receding motion similar to the mule or drawing-frame. By this 
 revolution and recession the spindles perform the operation of 
 spinning and stretching ; and at such intervals as the spindles 
 are stretching and twisting, the feeding-cloth stops, and the 
 clasps seize hold of the roving, and detain it till sufficiently 
 spun and twisted, when it relieves it in order to allow a fur- 
 ther portion of the rowan to be fed. The roving having by 
 this means received a certain degree of twist, is built on a 
 spindle in the form of a cop, as in mule-spinning, and is then 
 taken to the machine called the jenny. 
 
 The operation of i\i& jenny is nearly the same as the roving- 
 billy ; the only material difference is, that the cops of roving 
 to be spun are fixed upon a moving carriage, which has 
 clasps to hold the roving while in the act of being stretched 
 and spun into yarn. 
 
 Having now concluded the process of jenny-spinning, it 
 will be seen, that drawing and plying, the two essential requi- 
 sites for producing fine yarn, by placing the fibres parallel to 
 the length of the twist, are wanting, and that fine yarn, in 
 consequence, cannot be produced ; but the fibres in this pro- 
 cess being placed in a direction more across the length of the 
 twist, give to the yarn a rich fulness which renders it prefer- 
 able for the weft of heavy goods, for which it is esteemed. 
 
 TF ater-spinning differs both from the mule and jenny spin- 
 ning ; but the carding and drawing machines are the same as 
 those used in the process of mule-spinning. When the cotton 
 has passed through the carding and drawing machines^ it is 
 
AND MACHINIST. 
 
 387 
 
 carried to the spinning-frame, which is upon a different prin- 
 ciple to the mule, and, indeed, is more closely allied to the 
 bobbin and flier roving-frame. 
 
 One of these spindles is represented in fig. 406. A, the bobbin, brought 
 from the roving-frame ; B C and E guides for the yarn to pass through ; 
 G G Ci three pairs of rollers to perform the office of drawing ; and H a flier, 
 formed solid, and having at the end of one arm a small twist like a cork- 
 screw, through which the yarn passes. By the revolution of the flier the 
 yarn receives the requisite degree of twist, and is wound upon the bobbin, 
 whioh, by the movement of the seat I I, on which it rests, has an upward 
 and downward motion, in order that the yarn may be received upon it regu^ 
 larly. The guide C has a slow reciprocating motion in the direction of the 
 axes of the rollers G G G, by which the roving is moved over the surfaces 
 of the rollers, so that the parts wear uniformly. 
 
 In water twist-spinning, the operation of stretching is not 
 introduced. The motion is transmitted from the first mover 
 to the drawing and roving frames by means of bevel- wheels, 
 placed on the end of the frame. These wheels communicate 
 motion to the rollers, which have spur-wheels upon their 
 shafts, adapted to give motion to each other by intermediate 
 wheels, which give to the lower rollers motion in the proper 
 direction. The spindles receive their motion from bands 
 communicating with the drum K, represented by the dotted 
 lines. This construction of a water spinning-frame is called a 
 throstle^ and the difference which characterises it from that 
 properly called the water-frame is, that the cylinder K runs 
 through the whole length of the frame, and gives motion to 
 all the spindles at once ; whereas in the water-frame the 
 spindles are moved by an upright pulley, communicating 
 motion to only one set of six spindles, which is an advantage, 
 as the motion of one set can be stopped without stopping the 
 motion of the whole. But as the water-frame is far more 
 expensive than the other, it is a matter of doubt which ought 
 to be preferred. 
 
 The several sorts of yarn have each their peculiar destina- 
 tion. The yarn from mule and jenny spinning is taken from 
 the frame in the form of a cop ; that from water-twist is 
 wound upon a bobbin. The yarn from water-frames possesses 
 much regularity and strength, and is mostly used for the warps 
 of heavy goods, such as fustians and strong calicoes. If the 
 yarn has to be packed for the market, it is reeled upon a frame 
 consisting of six horizontal bars supported on an axis parallel 
 to each other. 
 
 T^is frame k represented in section, in fig. 407; A A A A A A the 
 horizontal bars ; B the axis ; and C the bobbin from the water-frame. The 
 dotted lines represent the direction of the twist. These reels are of a suffix 
 eieiit breadth to wind off about 50 cops, or bobbins, at the same time. 
 
 2c2 
 
388 
 
 THE OPERATIVE MECHANIC 
 
 When the reel has made 80 revolutions^ a small bell that is 
 connected with the machinery rings, and warns the attendant 
 to stop the motion of the reel. The portion thus wound is 
 called a lay, and seven of these lays wound upon the same 
 reel constitute a hank, which is taken from the reel by 
 causing one of the horizontal bars, supplied with a hinge, to 
 fall inwards. The circumference of the reel is a yard and a 
 half ; consequently the hank measures 840 yards. The size 
 of the twist is expressed by stating how many hanks go to 
 the pound weight : thus, the yarn called N® 100 is that whicli 
 takes 100 hanks of 840 yards each to weigh an avoirdupois 
 pound. Yarn can be spun upon mules as fine as 200 hanks 
 to the pound ; but in water-twist and jenny-spinning it seldom 
 exceeds 60 or /O. 
 
 The plan of the buildings in which the cotton-spinning 
 machinery is placed, is generally in the form of a parallel- 
 ogram, of a length proportionate to the extent of the manu- 
 facture carried on therein, and about thirty feet wide. In the 
 best constructed mills, the carding and other preparatory 
 machines are placed on the lowest floor; the mules and 
 stretching frames on the next ; and so on progressively as 
 the machines improve the fineness of the yarn. The mules, 
 jennies, and water-frames are placed with their line of spin- 
 dles across the building ; and the card-engines have the axes 
 of their cylinders parallel to the long wall of the building. 
 Four or six rows, breakers and finishers, are placed alter- 
 nately. , 
 
 The steam-engine, or first mover, is placed at one end of 
 the building, and the motion is communicated by a horizontal 
 shaft running the whole length of the building, which trans- 
 mits the motion to vertical shafts with bevel-wheels, which 
 wheels transmit the motion to horizontal shafts in the upper 
 floors. 
 
 WOOL MANUFACTURE. 
 
 This well-knowm staple is in the process of the manufac- 
 ture divided into two distinct classes, long wool, or worsted 
 spinning ; and sliori ivool, or the sjnnning of woollen yarn, 
 
 ON WORSTED SPINNING. 
 
 Having by means of machinery accomplished the forma- 
 tion of a thread of cotton, the application of the principle to 
 
AND MACHINIST. 
 
 389 
 
 other fibres would naturally follow ,* and although some diffi- 
 culty might be expected to occur in adapting the rollers to 
 different staples, yet this was soon overcome. The methods 
 of forming threads from long wool and from flax, by the 
 hand, were very different, yet each was spun from the middle, 
 not from the end, of the respective fibre. In hand-spinning, 
 the pluck, that is, the portion plucked from the sliver or 
 combed wool, was placed across the fingers of the left hand 
 and from the thick part of it, the fibres were drawn, and 
 twisted, as the hand was withdrawn from the end of the 
 spindle, to which it had been previously attached. The 
 revolution of the wheel, effected by the right hand, conveyed 
 by a band to the whirl, or pulley on the spindle, produced 
 the requisite twist to give firmness to the thread ; and by a 
 very gentle motion of the same wheel, the thread being 
 brought nearly perpendicular to the spindle, -it was wound 
 upon the spindle to form the cop. From this it w^as trans- 
 ferred to the reel, and became a hank, of a definite length, 
 but varying in weight with the thickness of the thread. In 
 this state it was transferred to the manufacturer to be con- 
 verted into the different fabrics of slialloon, calimanco, 
 bombasin, &c. 
 
 A few years after the introduction of cotton machinery, an 
 obscure individual of the name of Hargraves, previously 
 unknown as a mechanic, w^ho had been long employed by 
 Messrs. William Birkbeck and Co. at Settle, in Yorkshire, 
 in the management of a branch of the worsted manufactory, 
 attempted to spin long w'ool by means of rollers. He con- 
 structed working models of the necessary preparing machinery, 
 and of a spinning-frame, by the assistance of persons accus- 
 tomed to the construction of cotton machinery, and succeeded 
 so completely, as soon to induce his employers to build a 
 large mill for its application. By degrees his plans became 
 known to the trade, and many large manufactories have 
 subsequently been erected for this purpose. Contrary to 
 the earlier anticipations on this subject, it has been found, 
 that mill -spun yarn answers better for the coarse as well as 
 the finer fabrics, than that produced by the hand, which it 
 has entirely superseded. 
 
 The first process after the wool of the fleece has been 
 properly sorted, as it is termed, and washed, is combing. 
 This is either done by the hand or by machinery, invented 
 for that purpose some years since by the ingenious Dr. Cart- 
 wright. The object of each mode is to arrange the fibres as 
 much as possible parallel to each other, which, as they have 
 
390 
 
 THE OPERATIVE MECHANIC 
 
 a somewhat tortuous form, and are of considerable length, 
 requires them to be frequently drawn from each other by the 
 exertion of the strength of the wool-comber or the machine. 
 In this state they form a bundle of fibres about six feet ia 
 length, called a sliver, and this being laid upon the stretch • 
 ing or drawing frame, constitutes the commencement of the 
 preparing process. The wool passes through several pairs of 
 rollers of which the first and last are of course the essential 
 ones, the intermediate moving with equal velocities, and 
 consequently serving merely to conduct the skein : this is 
 received in cylindrical cans ; and three such skeins being 
 passed through another drawing-frame, and stretched in their 
 progress, become fitted for roving, the last step in the pre- 
 paratory processes. Allowing for the difference in distance 
 of rollers and weights, which on account of the length and 
 adhesiveness of the fibres of wool, are both necessarily 
 greater than with cotton, the description of the bobbin roving 
 machine already introduced, will be sufficiently explanatory. 
 
 Spinning, the concluding process, is effected by means of 
 two pairs of rollers moving with unequal velocities, and inter- 
 mediate auxiliaries. 
 
 The loosely twisted thread from the roving bobbin, E, fig. 408, is slowly 
 carried forwards by the holding rollers A, a, and supported as it proceeds 
 by the two pairs, C, c, and D, d. It is then drawn between the rollers B, 6, 
 and having been thus brought to a proper thickness, is twisted by the 
 flier L, fixed on the top of the spindle, through which at K it passes : it is 
 then taken up by the bobbin M, which moves round with the spindle its 
 axis, although not equally quick. The ultimate thickness or size of the 
 thread is determined by the difference of velocity in the holding and drawing 
 pairs of rollers ; that is of A, a, and B, b, which in their operation evidently 
 imitate a pair of hands. The celerity of the three pairs of rollers nearest to 
 the back of the frame is equal ; consequently no stretching takes place 
 amongst them. The upper rollers of the first and last pair are pressed 
 down upon the lower, by weights, F, G, much heavier than H, I, which are 
 supported by the axes of C, D ; these being only required steadily to carry 
 forward the skein, and prevent the remote ends of the fibres of the wool 
 from starting, whilst B, h, are pulling their other extremities. The front 
 rollers belonging to or^e division, or box, as it is commonly termed, are 
 represented in fig. 409, where the drum, which moves the spindles, and by 
 a bevelled pinion at the top of its axis conveys motion to the rollers, is also 
 shown. The pinion on the right extremity of the roller, acting upon a 
 train of wheels properly adjusted, imparts the required relative motion, in 
 succession, to the rollers beyond. 
 
 SHORT WOOL. 
 
 Short wool is wrought into the finest cloths for personal 
 wear, and is spun in a manner similar to cotton, as described 
 in jenny- spinning. 
 

 < I 
 
AND MACHINIST, 391 
 
 The first stage of the manufacture consists in submitting 
 it to the action of chamber-ley and frequent rinsings in clean 
 water, which bring it to the state fit for the operation of 
 carding. The carding-engine for fine short wool is con- 
 structed with one main cylinder, having, in lieu of the top 
 cards used in jenny-spinning, numerous small rollers, lying 
 and rolling upon its upper surface ; it is used in place of a 
 breaker-engine, and is called a scribbler. The wool is deli- 
 vered from a main cylinder to a doffer, and, being combed 
 or doffed, is carried to another engine, called the carder^ 
 which perfects the carding, and delivers it off, by means of 
 grooved mahogany rollers, in a row or rowan, as in jenny- 
 spinning. If the wool is of a coarse description, such as is 
 formed into yarn for the manufacture of coarse cloths or 
 woollen cords, more carding is required. 
 
 The scribbler-engine has three distinct parts or cylinders 
 in one frame. The first part consists of the first main cylin- 
 der with its top rollers, and is called the breast ; this delivers 
 the wool to the second main cylinder, which, with its top 
 rollers, is- called the first part ; this delivers it to a small 
 intervening cylinder, called the Tween doffer, which carries 
 it to the third main cylinder, which, with its top rollers, is 
 called the second part ; from hence it goes to the last doffer 
 cylinder, from which it is combed by a doffing-plate, and 
 finally carried by hand to a carding-engine. 
 
 The carding-engine consists of similar parts to the scrib- 
 bler-engine, except that it has no breast cylinder, and is 
 covered with finer cards : its last doffer delivers the wool to 
 a mahogany grooved roller, which forms it into rowans for 
 the process of spinning. 
 
 The act of continuous carding, as described in mule-spin- 
 ning in the cotton manufacture, is said to have been effected 
 in some mills, but the advantages arising from it are not so 
 great as to procure it general introduction. ' 
 
 The rows or rowans are taken to a roving-billy, which we 
 have already noticed in jenny-spinning, and is spun and 
 stretched by hand as there described. In this, however, the 
 act of plying and drawing is not introduced, as fineness of 
 yarn is not the object sought. 
 
 The engines used in carding wool are generally larger 
 than those used for cotton, being frequently six feet wide ; 
 during the operation of carding, the wool is copiously sprinkled 
 with rape oil. 
 
392 
 
 THE OPERATIVE MPX'HANIC 
 
 SILK MANUFACTURE. 
 
 Silk is a very fine and delicate thread, the produce of a 
 small insect, called homhyxy or the silk- worm ; which is not 
 less curious on account of the changes it undergoes in its 
 existence, than valuable for the beautiful fibre which it spins. 
 
 The egg, requiring not the care of parental incubation, is 
 by the solar heat brought into existence, and the bomb3^x or 
 silk-worm thus produced lives upon the leaves of the mul- 
 berry-tree until it has arrived at maturity, when, spinning 
 itself up in a small bag, about the size of a pigeon’s egg, it is 
 changed into an aurelia. In this state it continues till about 
 the fifteenth day when it is changed into a butterfl}", and, if 
 not prevented, eats its way through the silken prison, to 
 expand its newly acquired wings in the sun. 
 
 The ball or cocoon, which the ingenious little insect has 
 been at so much pains to spin, to secure itself from its 
 enemies and the eftects of the weather, is the substance we 
 call silk ; and many who have examined it with attention 
 are of opinion that it will extend to the distance of six English 
 miles. 
 
 In order to secure the silk foi the purposes of the manufac- 
 turer, it becomes necessary to destroy the insect so soon as 
 the cocoon is completed, which is on or about the tenth da}% 
 The cocoon is of various colours ; but the most predominant 
 are flesh colour, orange, and yellow. The whole of them, how- 
 ever, are lost in the process of scouring and dying, and there- 
 fore it is not necessary to wind them on separate reels. 
 
 The balls, preparatory to being wound oft' into skeins or 
 banks, are immersed in hot water, which dissolves a natural 
 gum, by which the fibres are united together, so that a single 
 thread taken from the reel will be found to be composed of 
 numerous small fibres or threads in the state produced by the 
 worm. 
 
 The silk is imported into this country thus wound off into 
 skeins, and in order to undergo the processes of the manu- 
 facturer is wound upon bobbins ; and each thread being, as 
 we before have stated, composed of several fibres, receives a 
 pertain degree of twist, that the constituent parts may be 
 united more firmly together than they can possibly be by the 
 gum alone. When the^" have been subjected to thus much of 
 the manufacture, they are wound upon fresh bobbins, and two 
 or three threads twisted together, to form a strong thread for 
 
AND MACHINIST. 
 
 393 
 
 tiie weaver^ who warps and finally weaves the silk into various 
 beautiful and useful articles, by a process very similar to 
 that used in the weaving of cotton and linen. 
 
 In Piedmont, vihere very excellent silk is produced, the manufacture is 
 carried on by aid of the silk reel represented in fig. 424. 
 
 The balls or cocoons are thrown into hot water contained in a copper basin 
 or boiler. A, about 18 inches in length, and six deep, set in brick-work, so 
 as to admit of a small charcoal fire beneath it. B B is a wood frame sustain- 
 ing several parts of the reel ; D is the reel upon which the silk is wound ; C 
 is a guide which directs the thread upon it; and E E the wheel-work which 
 gives motion to the guide. The reel D is merely a wooden spindle, having 
 four arms mortised into it to support the four battens or rails on which the 
 silk is wound. 
 
 Upon the end of the wooden spindle of the reel, and within the frame B, 
 is a wheel of 22 teeth, which gives motion to another wheel C, fixed upon 
 the end of the inclined axis E F, and having twice the number of teeth ; at 
 the end of this inclined axis is another wheel G, of 22 teeth, playing in a 
 horizontal cog-wheel with 35 teeth. This wheel turns upon a pivot fixed in 
 the frame, and has a pin fixed in it at a distance from the centre, to form an 
 eccentric pin or crank, and give a backward and forward motion to the slight 
 wooden rail or layer C, which guides the threads upon the reel; for this pur- 
 pose, the threads are passed through wire loops or eyes, C, fixed into the layer, 
 andtlie end thereof opposite the wheel and crank F is supported in a mortise 
 or an opening made in the frame B, so that the revolution of the crank wall 
 cause the layer to move, and carry the threads alternately towards the right 
 or left. Tiiere is likewdse an iron bar H, fixed over the boiler at H, and 
 pierced with two holes, through which the threads pass to guide them. 
 
 In the operation of reeling, it is well known, that if the 
 thread be wound separately it will be totally unfit for the pur- 
 poses of the manufacturer; consequently the ends of the 
 threads of several balls or cocoons are joined and wound to- 
 gether, and when any one of them breaks or comes to an end, 
 its place is supplied by a new one, and thus by continually 
 keeping up the same number the united threads may be wound 
 to any required length. 
 
 The reeling is conducted by a woman, who, when the balls 
 or cocoons have remained a sufficient time in the hot-water 
 contained in the boiler A, to soften the gum, takes a whisk of 
 birch or rice-straw, about six inches long, cut stumpy like a 
 worn-out broom, and brushes the cocoons with it, which 
 causes the loose tlireads to adhere to it ; these she disengages 
 from the whisk, and by drawing them through her fingers cleans 
 them from the loose silk, which always surrounds the cocoon, 
 till they come off clean, which operation is called la hattue. 
 When the silk has been perfectly cleansed, she passes four or 
 more of the threads, if she intends to wind fine silk, through 
 each of the holes in the thin iron bar H, and afterwards 
 twists the two compound threads, consisting of four cocoons 
 each, about 20, or 25 times round each other, that the four 
 
THE OPERATIVE MECHANIC 
 
 394 
 
 ends in each thread may the better join together by crossing 
 each other^ and that the thread of the silk may be round 
 which otherwise would be flat. 
 
 The threads when thus twisted together are passed through 
 the eyes of the loops, C, of the layer, and thence are conducted 
 and made fast to one of the rails of the reel. As it is of con- 
 sequence in the production of good silk, that the thread should 
 have lost part of its heat and gumminess before it touches the 
 bars of the reel, the Piedmontese are by law obliged to have 
 38 French inches between the guides, C, and the centre of 
 the reel ; and the layer must also, under a penalty, be 
 moved by cog-wheels instead of an endless-cord, which, if 
 suffered to grow slack, will cause the layer to stop and not 
 lay the threads distinctly, and that part of the skein will be 
 glued together, whereas the cog-wheel cannot fail : when the 
 skeins are quite dry, the reel is removed from the frame, and 
 by the folding of two of its arms, by means of hinges, the 
 skeins are taken off, and with some of the refuse silk are tied 
 into hanks. 
 
 Although from the foregoing description the operation 
 must appear very simple, it is a matter of very great nicety 
 to wind an even thread, and the difficulty of keeping the 
 thread always even is so great that, except when using a 
 thread of two cocoons, they do not say a silk of three, four, 
 or six cocoons ; but a silk of three or four, four or five, five 
 or six cocoons. In a coarser silk it cannot be calculated 
 even so nearly as to four cocoons, and consequently they say, 
 from 12 to 15, from 15 to 20, and so on. 
 
 It is also necessary that the water in the boiler be kept at 
 a certain temperature ; for if the water is too hot, the thread 
 is dead and has no body ; if too cold, the ends of the threads 
 do not join well, and form a harsh silk. The threads them- 
 selves indicate when the water is not at the proper degree of 
 temperature, by frequent breaking when it is too hot ; anc} 
 coming off entangled, and in a woolly state, when too cold. 
 
 In the process of winding the woman has always a bowl of 
 cold water by her, into which she occasionally dips her 
 fingers, and frequently sprinkles it upon the iron bar H, that 
 the threads may not be burnt by the heat of the basin ; it also 
 serves to lessen the temperature of the water in the boiler 
 when approaching the boiling point. 
 
 All kinds of silk which are simply drawn from the cocoons 
 by the process of reeling are called raw silk, and is denomi- 
 nated coarse or fine according to the number of fibres of 
 which the thread is composed. In preparing the raw silk for 
 
AND MACHINIST. 
 
 395 
 
 dying the thread is slightly twisted, in order to enable it to 
 bear the action of the hot liquor without the fibres separating 
 or furring up. The silk-yarn employed by the weaveis for 
 the woof or weft of the stuffs which they fabricate, is composed 
 of two or more threads of the raw silk, slightly twisted by the 
 aid of machinery ; and the thread employed by the stocking- 
 weaver is of the same quality, but composed of a greater 
 number of threads, according to the thickness required. 
 
 Organzine silk consists in combining together two or more 
 threads of silk, each of which has in the first instance been 
 twisted by itself, and afterwards the whole are twisted toge- 
 ther. This operation, with the exception of the elongation 
 of the cotton, closely resembles roving in the Cotton Manu- 
 facture. The process consists of six different operations. 
 1 . The silk is wound from the skein upon bobbins in the 
 winding-machines. 2. It is then sorted into different quali- 
 ties. 3. It is spun or twisted on a mill in the single thread, 
 the twist being in the direction of from right to left, and more 
 or less tight, as the purposes to which the silk is to be applied 
 may require. 4. Two or more threads thus spun are doubled 
 or drawn together through the fingers of a woman, who at 
 the same time cleans them, by taking out the slubs which 
 may have been left in the silk by the negligence of the foreign 
 reeler. 5. It is then thrown by a mill, that is, two or more 
 threads are twisted together, either slack or hard, as the 
 manufacturer may require ; but the twist is in an opposite 
 direction to the first twist, and it is wound at the same time 
 in skeins upon a reel. 6. The skeins are sorted according 
 to their different degrees of fineness, and then the process is 
 complete. 
 
 The first operation w'hich the raw silk undergoes is winding, 
 that is, drawing it off from the skeins in which it is imported, 
 and winding it upon wooden bobbins, in which state it can 
 go to the other machines. 
 
 Each of the skeins is extended upon a slight reel called 
 a swift ; it is composed of four small rods, fixed into an axis, 
 and small bands of string are stretched between the arms to 
 receive the skein, but at the same time the bands admit of 
 sliding to a greater or less distance from the centre, so as to 
 increase the effective diameter of the reel, according to the 
 size of the skein, because the skeins, which comes from dif- 
 ferent counti’ies, vary in size, being generally an exact yard, 
 or other similar measure, of the country where the silks are 
 produced. The swifts are supported upon wire pivots, upon 
 which tliey turn freely when the silk is drawn off from them ; 
 
396 
 
 T}1E Ol’ERATIVE MECHANIC 
 
 but ill order to cause the thread to draw with a gentle force, 
 a looped piece of string or vvire is hung upon the axis within- 
 side the reel, and a small leaden weight is attached to it, to 
 procure friction. The bobbins which draw off the threads are 
 received in the upper part of the frame, and are turned by- 
 means of a wheel beneath each, the bobbin having a small 
 roller upon the end of it, which bears by its weight upon the 
 circumference of the wheel, and the bobbin is thereby put in 
 motion to draw off the silk from the swift. A small light rod 
 of ivood, called a layer, which has a wire eye fixed into it, is 
 placed at a little distance from, and opposite to, each bobbin, 
 so as to conduct the thread thereupon 5 and as the layer moves 
 constantly backwards and forwards, the thread is regularly 
 spread upon the length of the bobbin. The motion of the 
 layer is produced by a crank fixed upon the end of a cross- 
 spindle, which is turned by means of a pair of bevelled wheels 
 from the end of the horizontal axle, upon which the wheels for 
 turning all the bobbins are fixed. 
 
 These winding-machines are usually double, to contain a 
 row of bobbins and swifts at the back as well as in front. 
 Two of these double frames are put in motion by cog-wheels 
 from a vertical shaft, which ascends from the lower apart- 
 ments of the mill, where the twisting-machines are placed. 
 The winding-machines require a constant attendance of 
 children to mend the ends of threads -wdiich are broken ; or 
 when they are exhausted, they replace them by putting new 
 skeins upon the swifts. When the bobbins are filled, they 
 are taken away, by only lifting them up out of their frame ; 
 and fresh ones are put in their places. 
 
 A patent has been lately taken out by l^iessrs. Gent and 
 Clarke, for a new construction of the swifts for winding- 
 machines : they are made with six single arms, instead of four 
 double ones ; and the arms are small flat tubes made to con- 
 tain the stems of wire forks, which receive the skein, instead 
 of the bands of string in the common swifts. These forks 
 admit of drawing out from the tubes until the swift be suffi- 
 ciently enlarged to extend It ; but as they extend the skein 
 at six points instead of four, as in the common ones, the 
 motion is more regular. Instead of the weight v/hich causes 
 the friction, a spring is used to press upon the end pivot of 
 the axis, and make the requisite resistance. 
 
 The twisting of the silk is always performed by a spindle 
 and bobbin, with a flyer, but the construction of the machine 
 is frequently varied. The limits of our plate do not admit 
 a representation of the great machines, or throwsting-mills, 
 
S II. K MANVYJ^ C T r ]R!B 
 
 FL.69.li; 00. 
 
 I 
 
AND MACHINIST. 
 
 397 ^ 
 
 at theii‘ full extent ; but the principle is the same as %, 426, 
 which we have extracted from Dr. Rees’s Cyclopaedia, varying^ 
 the description a little, to agree with the present improved 
 state of the manufacture. 
 
 In fig. 426, we have given a drawing of a small machine, which is similar 
 in the parts which act upon the silk ; and indeed many mills employ such 
 machines constructed on a large scale. The one in our plate contains only 
 thirteen spindles, and is intended to be turned by hand, a method which is 
 too expensive for this country, but is common in the south of France, where 
 many aitisans purchase their silk in the raw state, and employ their wives 
 or children to prepare it by these machines, which they call ovules, because 
 the spindles, b b, are arranged in an oval frame, G II. 
 
 B is the laandle by which the motion is giv^en ; it is fixed on the end of a 
 spindle 11, which carries a wheel D, to give motion to a pinion upon the 
 upper end of a vertical axle E ; this, at the lower end, has a drum or 
 wheel F, to receive an endless strap or band, a a, which encompasses the 
 frame G, and gives motion to all the spindles at once. The spindles b b are 
 placed perpendicularly in the frame G H, their points resting in small holes 
 in pieces of metal, which are let into the oval plank G ; and the spindle's 
 are also received in collars affixed to an oval frame II, which is supported 
 from the plank G, by blocks of wood ; rinnd a are small rollers supported in 
 the frame G H, in a similar manner to the spindles ; their use ij to confine 
 the strap «, to press against the rollers of the spindles with sufficient force to 
 keep them all in motion. 
 
 The thread is taken up, as fast as it is twisted, by a reel K, which is 
 turned by a wheel h, and a pinion i, upon the end of the principal spindle R. 
 The threads are guided by passing through wire eyes, fixed in an oval 
 frame L, which is supported in the frame of the machine, by a single bar or 
 rail 1 1, and this has a regular traversing motion backwards and forwards, 
 by means of a crank or eccentric pin R, fixed in a small cog-wheel, which 
 is turned by a pinion upon the vertical axis E ; the opposite end of the 
 rail I is supported upon a roller, to make it move easily. By this means 
 the guiders are in constant motion, and lay the threads regularly upon the 
 reel K, when it turns round, and gathers up the silk upon it as shown in the 
 figure. 
 
 One of the spindles is shown at r without a bobbin, but all the others are 
 represented as being mounted and in action. A bobbin, e, is fitted upon 
 each spindle, by the hole through it being adapted to the conical form of 
 the spindle, but in such manner that the bobbin is at liberty to turn freely 
 round upon the spindle ; a piece of hard wood is stuck fast upon each 
 spindle, just above the bobbin, and has a small pin entering into a hole in 
 the top of the spindle, so as to oblige it to revolve with the spindle, this 
 piece of wood has the wire-flyer, b, fixed to it ; the flyer is formed into eyes 
 at the two extremities ; one is turned down, so as to stand opposite to the 
 middle of the bobbin e ; and the other arm, b, is bent upwards, so that 
 the eye is exactly over the centre of the spindle, and at a height of some 
 inches above the top of the spindle. The thread from the bobbin, e, is 
 passed through both the eyes of this wire, and must evidently receive a 
 twist v/hen the spindle is turned ; and at the same time, by drawing up the 
 thread through the upper eye, b, of the flyer, it will turn the bobbin round,, 
 and unwind therefrom. The rate at which the thread is drawn off from the 
 bobbin, compared with the number of revolutions which the flyers make in 
 the same time, determine the twist to be more or less hard. This circum- 
 stance is regulated by the proportion of the wheel h to the pinion i, from 
 
I 
 
 THE OPERATIVE MECHANIC 
 
 398 
 
 ■wliicn it receives motion ; and these can be changed when it is required to 
 spin different kinds of silk. 
 
 The operation of the machine is very simple. The bobbins filled with 
 silk in the winding-machine, fig. 425, are put loose upon the spindles at 
 and the flyers are stuck fast upon the top of the spindles ; the threads are 
 conducted through the eyes of the flyers b, and of the layers L, and are then 
 made fast to the reel K, upon which it will be seen that there are double 
 the number of skeins to that of the spindles represented, because one half 
 of the number of spindles is on the opposite side of the frame, so that they 
 are hidden. With this preparation the machine is put in motion, and 
 continues to spin the threads by the motion of the flyers, and to draw them 
 off gradually from the bobbins, until the skeins upon the reel are made up 
 to the requisite lengths. This is sometimes known by a train of wheel-work 
 at u op, consisting of a pinion, «, fixed upon the principal spindle R, 
 turning a wheel, o, which has a pinion fixed to it, and turning a larger 
 ivheel p ; this has another wheel upon its spindle, with a pin fixed in it,- 
 and at every revolution raises a hammer and strikes upon a bell, s, to inform 
 the attendant that the skeins are made up to a proper length. 
 
 In the silk-mills they employ two different machines, one 
 for the first operation on organzine, and the other for the 
 second operation. 
 
 Thus, after the silk is twisted it must be wound on fresh 
 bobbins, with two or three threads together, preparatory to 
 twisting them into one thread. In the original machines at 
 Derby this was done by women, who, with hand-wheels, 
 wound the threads from two or three of the large bobbins 
 upon which the silk is gathered instead of the reels, and 
 assembled them two or three together upon anotlier bobbin^ 
 of a proper size to be returned to the twisting-mill. 
 
 In 1800, Mr. John Sharrar Ward, of Bruton, obtained a 
 patent for a new method of doubling silk, worsted, cotton, or 
 flax, which we intend to describe here ) for though various 
 modes are adopted for this purpose, one will be sufficient to 
 give an idea of the whole. Whatever number of threads may 
 be required to be doubled together, they may by means of 
 this invention be doubled to the greatest certainty ; for if at 
 any time any one of the threads, or union of threads, to be 
 so doubled, should break, it will immediately stop the other 
 thread or threads until the broken thread shall be repieced, 
 which secures a constant double thread, or union of threads ; 
 and the manner in w^hich the same is to be performed will, we 
 trust, be clearly understood by the subjoined description. 
 
 Tig. 429. A is a roller carrying round the bobbin B, which draws the 
 threads C C from the bobbins D D ; consequently the balls E E, and the 
 thread-wires F F, move round on the pins G G. H H are two wood or iron 
 standards, at the tops of which are hung two regulating thread-wires, 1 1. 
 \V hen either of the threads C C break, the thread-wire through which it 
 passes falls down, and the tail part K rises up to a level with the ball E, and 
 stops the other thread-wire from going round, and consequently the thread 
 
and machinist^ 
 
 399 
 
 that passes through it, arid prevents the bobbin B from taking it up ; but 
 tlie roller A continues its motion. L L are guide-wires for the threads to 
 pass over ; M is a slide, moved by a short wheel or crank, to lay the threads 
 level on the bobbins. 
 
 Fig. 430 is another doubling-machine, the form varied, but the principle 
 the same as fig. 429. A is a roller, whereon lies a smaller one, marked B, 
 the axis of which goes through the bobbin; C is a slide, for the same pur- 
 pose as M, in fig. 429 ; D D two bobbins, with spindles through them, on 
 each of which is fixed a wheel EE; F F are two thread-wires hung at G G. 
 When either of the threads break, the wires drop between the teeth of the 
 wheel, and stop the other thread, the bobbin and roller B stopping at the 
 same time ; but the roller A continues moving, as A in fig. 429. 
 
 The bobbins being thus filled with double or triple threads, 
 are carried back to the throwsting-machine, and are there 
 spun or twisted together in a manner similar to that before 
 described. At this period, the silk is a marketable article,, 
 and is passed from hand to hand. 
 
 Tlie silk being now spun, is put into a boiler filled with hot 
 water, into which is put a small quantity of soap, in order ta 
 divest the silk of its gum. In the earlier processes, the gum 
 was necessary for the purposes of the manufacture, for the 
 silk, had it been divested of it, would have assumed a fine 
 downy appearance similar to that of cotton, and must have' 
 undergone similar operations before it could have been formed 
 into a thread; this, indeed, is necessary for that portion of waste 
 silk which is drawn from the cocoons in the first operation 
 of reeling ; also for those cocoons which have been reserved 
 for breed, or which is made in the operations of twisting just 
 mentioned, through which the moth or butterfly has eaten 
 a hole, and rendered them impracticable to be wound off 
 into silk. 
 
 The silk is now taken to the warping-mill, w'hich, being a 
 precursor to the act of weaving, will be noticed under that head. 
 
 At this present moment several improvements are in pro- 
 gress for winding and throwing silk upon a new principle ; 
 indeed, the silk manufacture now may be compared with what 
 the cotton manufacture was about thirty years ago. There 
 appears to be taking place in every department the same 
 great and rapid improvements ; and it is much the opinion 
 of practical men, that the machinery now in use will, in the 
 course of a very few years, be entirely superseded, and that 
 this branch of our manufactures will ultimately be almost, if 
 not quite, as great a source of national prosperity as the 
 cotton manufacture. 
 
 The art of throwing silk was first introduced into this 
 country by Mr. John Lombe, who, with considerable inge- 
 nuity, and at the risk of his life, took a plan of one of these 
 
40t> 
 
 THE OPERATIVE MECHANIC 
 
 complicated macliines in the king of Sardinia’s dominion';? 
 from which, on his return, he, in conjunction with Mr, 
 Thomas Lombe, established a similar set of mills at Derby, 
 Parliament granted them a patent for fourteen years; and, on 
 being petitioned at the end of that term for a renewal, granted 
 them 14,000/. instead, on condition that they should allow 
 a perfect model to be made, and placed in the Tower for 
 public inspection. 
 
 . — — 
 
 FLAX MANUFACTURE. 
 
 Flax undergoes various processes before it can be worked 
 into cloth or other articles ; these processes are very diifcrent, 
 and require different sorts of implements and machinery, in 
 order to their being properly performed. Flax, for the pur- 
 pose of being formed into cambric, fine lawn, thread, and lace, 
 is dressed in rather a different manner to that which is em- 
 ployed for other purposes ; it is not scotched so thoroughly 
 as common flax, which from the scotch proceeds to the heckle, 
 and from that to the spinner ; whereas this fine flax, after a 
 rough scotching, is scraped and cleansed with a blunt knife 
 upon the workman’s knee, covered with his leather apron ; 
 from the knife it proceeds to the spinner, who, with a brush, 
 made for the purpose, straightens and dresses each parcel 
 before she begins to spin it. 
 
 In the Sivedish Transactions for the year 1747^ ^ method 
 is given for preparing flax in such a manner as to resemble 
 cotton in whiteness and softness, as well as in coherence ; 
 for this purpose, a little sea- water is directed to be put into 
 an iron pot, or an untinned copper kettle, and a mixture of 
 equal parts of birch-ashes and'quick-iime strewed upon it, 
 a small bundle of flax is to be then opened and spread upon 
 the surface, and covered with more of the mixture, and the 
 stratification continued till the vessel is sufficiently filled. 
 The whole is then to be boiled with sea-water for ten hours, 
 fresh quantities of water being occasionally supplied in pro- 
 portion to the evaporation, that the flaxy matter may never 
 become dry. The boiled flax is to be immediately washed in 
 the sea, by a little at a time, in a basket, with a smooth stick 
 at first, while hot ; and when grown cold enough to be borne 
 by the hands, it must be well rubbed, washed with soap, laid 
 to bleach, and turned and watered every day for some time. 
 Repetitions of the washing with soap expedite the bleaching ; 
 after which, the flax is to be beat, and again well washed ; 
 when dry, it is to be worked and carded in the same manner 
 
AND MACHINIST. 
 
 401 
 
 as common cotton, and pressed between two boards for forty- 
 eight hours. It is now fully prepared and fit for use. It 
 loses in this process neaidy one-half its weight, which, how- 
 ever, is abundantly compensated by the improvement made 
 in its quality, and its fitness for the finest purposes. 
 
 The Jiax-hrake is a hand instrument, or machine, which was originally, 
 and for many ages, chiefly employed in breaking and separating the boon or 
 core from the flax, which is the cuticle or bark of the plant. In performing 
 this business, the flax being held in the left hand, across the three under 
 teeth, or swords of the brake, shown at A, figs. 432 and 433, the upper 
 teeth or swords B, fig. 432, and 6, fig. 433, are then with the right hand 
 quickly and often forced dow n upon the flax, which is artfully shifted and 
 turned with the left hand, in order that it may be fully and completely 
 broken in its whole length. 
 
 The flax foot-brake is an implement, or machine, of the brake kind, 
 invented in Scotland, by which flax is broken and scotched wdth much 
 greater expedition than by the hand instrument just described, and in a 
 more gentle and safe manner than by the flax-mill. By this contrivance, 
 the boon or stem is well broken, and the sloping stroke given as with the 
 scotcher, while the machine is moved by the foot. The treadle is of con- 
 siderable length, on which account it is put in motion with great facility, 
 and assisted in it by means of a fly. Tlie scotchers are fixed upon the rim 
 of a fly-wheel. But though these machines may be highly useful where 
 mills turned by water cannot be established, they are probably much inferior 
 in point of expedition, and the economy of labour. A brake of this kind is 
 represented in different views, in figs. 434 and 435, in which is shown, by 
 A, the three under brake-teeth, or swords, seventeen inches long, three 
 inches deep, one inch and a quarter thick at the back, and a quarter of an 
 inch at the fore-part or edge. 
 
 B the edges, two inches and three-quarters asunder at the end next the 
 guide B, and two inches asunder at the other end. 
 
 C displays the two upper teeth, about an inch shorter than the under 
 teeth; and 
 
 D represents the brake-mallet, about thirty-three pounds English weight. 
 
 F is a compound foot-treadle, which is eight feet four inches between the 
 fulcra F, raised at F eight inches above the ground, or rather five inches 
 higher than the lance of the workman ; E is two feet four inches between 
 the fulcra G, and is raised at G eighteen inches above the ground ; that is, 
 fifteen inches higher than the lance of the workman. 
 
 H the sword, or upright timber rod, which turns the wheel by the treadle- 
 crank. 
 
 I the treadle-crank, cf seven inches and a half radius. 
 
 K the fly-wheel, four feet and a half diameter, above sixty pounds 
 English weight. As here represented, it is beat or cast iron ; but it may 
 also be made of timber. 
 
 L brass cods or bushes. 
 
 m M the lifting-crank ; M is fixed firm upon the axle of the fly, while the 
 crank about eight inches radius, plays freely round the axle. In position 
 first, M begins to take round the crank (which by the lever R pulls up the 
 mallet) ; when it oomes to position second, the mallet is again at liberty, 
 and by its weight pulls up the drank (faster than the fixed pieces move) into 
 position third. 
 
 It may be observed that the treadle-crank is ad^’anced about one-eighth 
 part of the circle before the lifting-crank. 
 
 2 D 
 
402 
 
 TIIK OPERATIVE MECHANIC 
 
 « a small pulley, which turns easily round on the end of the crank, and 
 to which a rope is fixed. 
 
 O a piece of timber which prevents the roller from falling in upon the 
 axle, but which should not rub against the rope in its coming down. 
 
 P shows where the rope passes between two friction-rollers, which are so 
 placed that it comes down three or four inches, or half the radius of the 
 lifting-crank on the side of the plummet-line, crossing the centre .of the 
 wheel ; that is, to the side on which the crank turns when it pulls dowai’ 
 the rope. 
 
 Q a pillar, which serves only to support the guard for the rope O, and the 
 friction-rollers at P. 
 
 P. the lever. t; '' 
 
 S the lever-pillar. 
 
 T part of the mallet-frame. 
 
 U two pillars which guide the brake-mallet. 
 
 V an iron spring which receives the leap of the mallet, and throws it the 
 quicker down. 
 
 W the pillars which support the fly. 
 
 X U the pillars which bear the brake-teeth and mallet. 
 
 Y Y the spur and cross that support the pillars. 
 
 Z Z the bottom frame-piece. 
 
 a the broad stool upon which the workman stands, three inches above the 
 ground. 
 
 The lifting crank and pulley are shown separately, in different views, at 
 M m n, and m u. 
 
 The brake-teeth are made of good beech or plane-tree ; the brake-mallet 
 of plane-tree, ash, elm, birch, or oak ; and the sword, or upright timber-rod, 
 between the treadle and the treadle-crank, of beech, ash, or oak. The fly- 
 wheel, if timber, should be made of oak, ash, beech, elm, or plane-tree. 
 All the other parts of timber worth mentioning may be made of fir-Vv^ood. 
 
 At fig, 436 is shown the ground plan of the whole. 
 
 This brake may at any time be converted to a beater of 
 flax and hemp, by removing the brake-teeth, and putting in 
 their place flat boards. In the upper of these boards may be 
 driven 32 nails, the heads about three-quarters of an inch 
 long, and the points of the heads about a quarter of an inch 
 in diameter ; the points of the nail-heads may be placed one 
 inch clear asunder, and at equal distances, as in this way any of 
 the nails may most easily be drawn out in repairing the mallet. 
 An iron hoop put about the mallet wdll prevent its bursting 
 with the driving in of the nails. In the time of beating, the 
 narrow end of the mallet is placed towards the workman, 
 and where there is much w^ork in that way, the mallet and fly 
 may be made heavier, and then two or more workmen can 
 work together upon the foot-treadles, which may also he 
 made equally long. 
 
 The flax-hackle is an instrument or tool constructed for the purpose of 
 hackling or straightening the fibres of the flax, which is seen at figs. 437 and 
 438. It has many teeth, fixed in a square flat piece of wood, as seen at 
 A and B. Wlicn used, it is firmly fixed to a bench before the workman, 
 who strikes the flax upon the teeth of the liackle, and draws it quickly 
 

 
 Ft. 61. 
 
 From .13? to 439 
 
 43F 
 
 • SlpJify 
 
AND MACHINIST. 
 
 403 
 
 through the teetli. To persons unacquainted with this kind of work, this 
 may seem a very simple operation ; but in fact it requires as much practice 
 to acquire the method of hackling well, and without wasting the flax, as any 
 other operation in the whole manufacture of linen. The workmen use 
 finer, or coarser and wider-teethed hackles, according to the quality of the 
 flax ; generally putting the flax through two hackles, a coarser one at first, 
 and then a finer one in finishing it. 
 
 The Jiax rippling-comb is an instrument or tool which is formed by letting 
 six, seven, or more long square teeth nearly upright, in a long narrow piece of 
 plank, so that their different angles shall come nearly to touch each other. 
 By drawing the flax through between these teeth, the balls or'pods in which 
 the seed is contained are forced off. It is seen at A and B, fig. 439. If 
 the flax is to be regarded more than the seed, it should, after polling, be 
 allowed to lie some hours upon the ground to dry a little, and so gain some 
 fiiTnness, to prevent the skin or harl, which is the flax, from rubbing off 
 in the rippling ; an operation which ought by no means to be neglected, as 
 the balls, if put into the water along with the flax, breed vermin, and other- 
 wise spoil the water ; the balls also prove very inconvenient in the grassing 
 and breaking. In Lincolnshire and Ireland they think that rippling hurts 
 the flax; and therefore, in place of it, they strike the balls against a stone. 
 The handfuls for rippling should not be great, as that endangers the lint in 
 the rippling-comb. After rippling, the flax-raiser will perceive that he is 
 able to assort each size and quality of the flax by itself more exactly than 
 he could before have done it. 
 
 The hand and foot methods of breaking and scotching the 
 flax are, however, too tedious in their operation to give satis- 
 faction to the manufacturers, in the present advanced state of 
 mechanical science ; consequently mills have been con- 
 structed, by which these preparatory operations are much 
 facilitated. 
 
 Flax-mills are constructed in great variety ; but one of 
 the best with which w'e are acquainted is described in Gray's 
 Experienced Millwright^ in nearly the following terms : — 
 
 Fig. 440 is the plan. A A, the water-wheel ; C C, the shaft or axle 
 upon which it is fixed ; B B, a wheel fastened upon the same shaft, 
 containing 102 teeth, to drive the pinion D, having 25 teeth, which is 
 fixed upon the middle bruising-roller ; E, a pinion in which are 10 teeth, 
 turned by the wheel B, which is fastened upon the under end of the 
 perpendicular shaft that carries the scotchers; MM, the large frame that 
 supports one end of the shaft C, and the perpendicular axle; NN are 
 frames in which the rollers turn that break or bruise the rough flax ; I A 
 . and L, the machine and handle to raise the sluice when the water is to be 
 let on the wheel A A, to turn it round ; G G, doors in the side walls of the 
 mill-house ; I K, windows to lighten the house ; H H, stairs leading up to 
 the loft. 
 
 Fig. 441 is the elevation. A A, the water-wheel upon its shaft C C, on 
 which shaft the wheel B B is also fixed; this latter wheel containing 102 
 teeth, to turn the wheel E, having 25 teeth, which is fastened upon the 
 middle bruising-rollei. F F is a vertical shaft, upon the lower end of 
 which is fixed a pinion having 10 teeth, which is driven by the wheel B. 
 riiere are two arms that pass through the shaft F ; and upon these arms are 
 fustetifidi with screwed iron bolts, the scotches that clear the refuse off the 
 
 2 D 2 
 
404 
 
 THIS OPERATIVE MECHANIC 
 
 flax. D D, the frames vrhicii support one end of tlie axle C, the vertical 
 shaft, and the break ing-roliers ; L is a weight suspended by a rope, the 
 other end of which is fastened to a bearer, as is seen in fig. 442 ; S S, a lever, 
 the short arm of which is attached to the frame tliat the gudgeons of the 
 upper roller turn in ; and by pushing down the long arm, the upper roller 
 is, when necessary, so raised as to be clear of the middle one. N N, the end 
 walls of the mill-house ; R R, the couples or frame of the roof ; H, a door in 
 the side wall ; I K, windows. 
 
 Fig. 442 is a section. A A, the great water-wheel fixed upon its sliaft, 
 and containing 40 aws, or float-boards, to receive the water which com- 
 municates motion to the whole machinery. B B, a wheel fastened upon the 
 same axle, having, as before mentioned, 102 cogs, to drive the wheel C, of 
 25 teeth, which is fixed upon the middle roller, No. 1. The thick part of 
 this roller is fluted, or rather has teeth all round its circumference ; these 
 teeth are of an angular form, being broad at their base, and thinner 
 towards their outward extremities, which are a little rounded, to prevent 
 them from cutting the flax as it passes through betwixt the rollers. The 
 other two rollers. Nos. 2 and 3, have teeth in them of the same form and 
 size as those in the middle roller, whose teeth, by taking into those of these 
 two rollers, turns them both round. The rough flax is made up into small 
 parcels, which being introduced betwixt the middle and upper rollers, pass 
 round the middle one; and this either having rollers placed on its off-side, 
 or being enclosed by a curved board that turns the flax out betwixt the 
 middle and under rollers, when it is again put in betw'ixt the middle and 
 upper one, round the same course, until it be sufficiently broken or softened, 
 and prepared for the scotching-machine. The bearer in which the gudgeon 
 of the roller No. 1 turns, is fixed in the frame at C ; and the gudgeons of 
 the rollers Nos. 2 and 3 turn in sliders that move up or down in grooves in 
 the frames S S. The under roller is kept up to the middle one by the 
 weights D D, suspended by two ropes going over tw'o sheeves in the frames 
 S' S ; their other ends being fastened to a transverse bearer below the sliders 
 in which the gudgeons of the roller No. 3 turn. The weights D D must be 
 considerably heavier than the under roller and sliders, in order that its teeth 
 may be pressed in betwixt the teeth of No. 1, to bruise the flax when passing 
 between the rollers. The whole weight of the roller No. 2 presses on the 
 flax which passes between it and No. 1. There is also a box fixed on the 
 upper edge of its two sliders to contain a parcel of stones, or lumps of any 
 heavy metal, so that more or less weight can be added to the roller, as is 
 found necessary. O O is the large frame that supports one end of the shaft 
 which carries the two wheels A B, and vertical axle F F ; on the lower 
 end of which is fixed the pinion turned by the wheel B, and having 10 teeth. 
 In the axle F are arms upon which the scotches are fastened with screwed 
 bolts, as seen at G G, fig. 441. These scotches are enclosed in the cylin- 
 drical box E E, having in its curved surface holes or porches at which the 
 handful of flax are held in, that they may be cleaned by the revolving 
 SGotchers. H H, the fall or course of the w'ater ; 1 1, the sluice, machine, 
 and handle for raising the sluice to let the wmter on the great wheel. The 
 gudgeons of the axles should all turn in cods or bushes of brass. K K, the 
 side walls of the mill-house ; G G, doors ; L L, windows. 
 
 Having’ proceeded thus far, the reader will have become 
 acquainted with the various modes of preparing flax for the 
 operation of spinning, which operation, from the copious 
 manner in which we have treated of it under the article 
 Cotton Manufacture, requires but little elucidation. 
 
]t’]LAX MIM. 
 
 From 440 to 4 43 
 
 Fl.Sz 
 
 SuteAl^ ^^4 Stt'nnd. 
 
AND MACHINIST. 
 
 405 
 
 About the 5 ^ear 1787? Messrs. Kendrew and Porthoiise, xyf 
 Darlington, obtained a patent for spinning a flaxen tliread hy 
 means of machinery ; prior to that time, we believe, the rock 
 and wheel, variously modified, occasionally for superior spin- 
 ners to form two threads at once, were universally employed. 
 In Ireland especially, even at the present day, this method is 
 much practised. The flax, rendered straight and smooth by 
 hackling, is wrapped loosely round the rock, from which it is 
 gradually drawn by the left hand, whilst the thumb and 
 fore-finger of the right, moistened with w^ater, are employed 
 in adjusting the fibres, and directing the thread. A bobbin 
 and flyer, placed upon a horizontal spindle, serve to give the 
 twist, and to take up the finished thread ; their motion is 
 derived from a wheel, impelled by the foot through a treadle 
 and crank, by means of an endless-band passing round a 
 pulley of much smaller diameter, which is fixed upon tlie 
 spindle. 
 
 The straightness aud smoothness of the fibres of flax, so 
 different from the corrugation and adhesiveness of cotton and 
 w’ool, with their extraordinary length, seemed to demand an 
 arrangement in machine-spinning very different from what 
 has been already delineated. 
 
 In the patent alluded to, the hackled flax was extended upon a hori- 
 zontal frame, at fig. 410% to be carried betw een the rollers B b, and after- 
 wards to pass along with the cylinder C, (revolving with a velocity equal 
 to that of any point of the circumference of B,) under several successive 
 rollers, until it arrived at the drawing-rollers D d ; the twdst and removal 
 of the thread then taking place by the flyer and bobbin, as before described. 
 The rollers E, F, G, H, I, if of equal weights, will, on account of their re- 
 spective positions, press with unequal force ; the one resting upon the vertex 
 of the cylinder being evidently the most efficacious, and with the surface 
 beneath acting probably the part of a pair of holding-rollers to fibres of tlie 
 length of nearly one-fourth of the circumference ; whilst for fibres which are 
 longer or shorter, the other rollers, according to their place, will answer the 
 .same purpose. In this, how ever, there i? no new principle ; and although 
 modified, it amounts merely to the.operation of holding and drawing rollers. 
 From some impediments thrown in the way of the Scotch flax-spinners by 
 the patentees before mentioned, they began, we believe, iu no long time, to 
 place their rollers in a stra.ight line, at distances suitable to the length of 
 the fibres. Of the excellence of this arrangement a working model made 
 for the A.ndersonian Institution in Glasgow, in the year 1803, afforded 
 sufficient evidence. 
 
 We shall now proceed to give a description of a patent, 
 obtained, in the year 1806, by Messrs. Clarke and Bugby, 
 for effecting certain improvements in a machine, intended to 
 be worked by hand-labour, for the spinning of hemp, flax, 
 tow, and wool. 
 
 Fig. 445 represents an cfolique view of the front of a frame containing 
 ten spindles, (W frames may contain an indefinite number of spindles.) A, 
 
406 
 
 THE OPERATIVE MECHANIC 
 
 the spindle or a bow passing through the whole frame, having ten bosses of 
 brass or cast-iron thereon, each about four inches diameter, each boss supply- 
 ing one spindle ; B, a pinion of twelve leaves upon the end of the spindle A, 
 connected with the wheel C, of eighty teeth, fixed upon the end of a small 
 iron spindle F, covered with wood and extending through the whole frame ; 
 D, a slack or intermediate pinion of any size at discretion, connected with 
 another similar pinion, the latter connected with a wheel of 120 teeth, 
 which is fixed upon an iron spindle G, of about inch diameter, and 
 extending through the whole frame ; but the wheels BCD and E may be 
 varied in their numbers, to increase or diminish the draught of the sub- 
 stance operated upon, as may best suit its quality or the ideas of the workman. 
 The pinion B is so contrived as to slip olf the end of the spindle A, to 
 make room for a smaller or larger one ; by means whereof a larger or shorter 
 thread may be spun from the same sized rovings ; aa a a a aa a a a repre- 
 sent ten roved slivers of hemp, flax, tow, or wool, passing between the iron 
 spindle G and rollers in pairs pressed against them by springs or weights ; 
 these springs or weights must be of sufficient force to hold back the slivers 
 or rovings so securely, that they may only pass on with the movement of 
 the spindle ; these pairs of pressing rollers are placed behind the spindle. 
 The use of the small iron spindle F, covered with wood, and left rather 
 larger than the spindle G, is, with pressure of the small wood roller, made 
 up in pairs h bbb 6, and so contrived that each pair may roll upon two 
 slivers, to bring them down straight, and preserve the twist which they 
 receive in the roving-machine till the slivers leave them. The bosses on the 
 spindle A have likewise wooden rollers in pairs pressed against them by 
 springs or weights, between which the drawn, lengthened, or extended slivers 
 pass to the spindle, the rollers having each a tin conductor ccccccccccj 
 to bring the material under operation as centrically as possible between the 
 wood rollers and the bosses; but all the above-mentioned parts of the 
 machine is so similar to the common upright frames for spinning flax, that 
 a person conversant with them will not be at a loss to make it all. H is a 
 wheel of wood four feet in diameter, having its rim about two inches thick, 
 with a groove in its periphery for a small cord or band. In its centre is a 
 rule or stock of wood through which the spindle I passes, and extends into 
 its frame about one-fourth of its length. To enable the person that turns 
 the winch to reach all the spindles at work, with the hand that is not 
 engaged in turning, to remove any obstacle that may arise to the spindles, 
 the arbor or spindle of the wheel I has its bearing on the sides of the frame 
 that contains it, marked L L L L ; this frame, with the wheel H, the arbor I, 
 and the winch K, is similar to that part of a machine called a mule-jenny, 
 used for spinning cotton ; this frame is supported in a horizontal position 
 at the outer end by two legs marked M M, and a screw pin which passes 
 through K, the front upright, a A, fig. 444, and made tight with the thumb- 
 screw a i the screw passes through a groove or mortise at the end of the 
 wheel frame, to enable the workman to adjust the wheels N and O, as it 
 will be found necessary to change the wheel N, to make such alteration in 
 the twist as the size of the yarn may require, or as the workman may think 
 proper. P and Q are bevel wheels of equal size, the former fixed upon 
 the rule or stock of the wheel H, and connected with Q upon the spindle R, 
 taking round with it the wheel N, which is connected with the wheel O. 
 Upon the embossed spindle or arbor A,aaaaaaaaaa, are spindles 
 standing on a carriage with four wheels, similar to the carriages used in 
 mule-jennies for spinning cotton, having at each of them, dddddddddddd, 
 a convex seat of wood of any convenient size, not less than the bottom of 
 the bobbins or quills eeeeeeeeee; these bobbins or quills are about six 
 

 3fcfU i: stfchlty. J-ajJl,Serw!ti 
 
AND MACHINIST, 
 
 407 
 
 inches long and inch diameter at the bottom, and three-quarters of an 
 inch diameter at the top ; but the sizes must be varied according to the 
 size of the yarn. Perhaps four or five variations will be sufficient to spin 
 yarn for tarpaulins or sail-cloth, up to fine yarn fit for good dowlas and 
 fine stockings. T a pulley, over which a band, from S, runs and returns, to 
 draw out the carriage upon the four wheels described ; W, the cylinder 
 which drives the spindles. 
 
 Fig. 444 exhibits a side view. A, the wheel mentioned above in fig. 445, 
 and there marked H ; B, the winch by which it is turned by hand ; C C C C, 
 the frame wherein it works ; D and E are blocks of wood on each side of 
 the said frame to raise the wheel, so that the winch may be clear of the 
 <?arriage F F, and apparatus G G ; the two end wheels upon the carriage 
 containing the spindles having two more corresponding on the opposite 
 side thereof. H, a groove upon the end of a cylinder, which drives the 
 spindles, and stretches through the carriage frame, for the diameter of 
 which no certain rule can be laid down, as it depends upon the length or 
 size of the yarn, taken into account with the other parts of the machinery. 
 NNNNNNN, a small band passing over the wheels A K, H I L and M, 
 by which the groove wheel H and its cylinder are moved, and the spindles 
 driven. O a treadle shaft, represented by S S, in fig. 445, passing through 
 the frame or part thereof at the option of the workman, connected with a 
 tumbler at the end of the embossed spindle or arbor A, in fig. 445, by a 
 small band, wound five or six times round each of them, and passing over 
 the wood groove wheel Q, and made fast to the back of the carriage FF ; 
 this tumbler, by the motion of A, is, at the return of the carriage, locked 
 to the wheel R; and unlocked when the carriage is not to its destined place. 
 
 The carriage is drawn on by the weight of S fastened to a cord, wliich 
 passes over the groove wheel T, and is connected with the front of the car- 
 riage ; U, the wheel on the arbor containing the holder shown in fig. 445. 
 V, the cylindrical roller on a stirt fixed therein, and rolling at every return 
 of the carriage on the plane W and X, which raises and falls the fallers and 
 holders, so as to distribute the yarn upon the bobbins from top to bottom ; 
 the wheels YZ, A 2, and B2, are the same wheels shown by B, C, D, and 
 E, in fig. 445 ; 1, 2, &c. spools containing the rovings. 
 
 This machinery is calculated to save the heavy expense of 
 currents of water, erecting spacious buildings, waterworks, 
 steam-engine, &c. and to spin hemp, flax, tow, and wool, at 
 such an easy expense, as to bring it within the reach of 
 small manufactories. This machinery is also constructed 
 upon such safe and simple principles, that no length of 
 experience is necessary to enable even children to work it ; 
 and the use of water, steam, &c. being rendered unnecessary, 
 it occupies so little space, that it may be placed in small 
 rooms, out-buildings, or other cheap places. To effect the 
 above purpose, it was necessary to get rid of the lanier or flyer 
 upon the spindle used in the old machinery for spinning 
 hemp and flax, which requires a power in proportion of 
 5 to 1, and to surmount the difficulty that arose from the 
 want of elasticity in these substances. This want of elasti- 
 city in the substance to be operated upon, is compensated 
 
408 
 
 THK OPERATIVE MECHANIC 
 
 and provided for in this machinery ; and upon this compensa- 
 tion and provision, effected by the various means hereafter 
 mentioned, the return of the carriage without any assistance 
 from the work-person, and the traverse for distributing the 
 yarn upon the bobbins or quills, lay the stress upon the 
 patent. The most simple mode of compensating the want 
 of elasticity, and which is recommended in preference to the 
 other, is that of having a holder of large wire for every 
 spindle fixed in an arbor or shaft extending from one end of 
 the carriage to the other. 
 
 This arbor or shaft, with the holders, may be considered as a large and 
 improved substitute for what is called a faller in the mule-jennies for spin- 
 ning cotton, fig. 443. Let A represent the arbor or shaft, bbbbbbbbbb 
 the holders fixed therein with the elliptical eyes, through each of which a 
 thread passes from the bosses on the arbor A, in fig. 445, to its spindle. 
 B, a spindle, which may be from 10 lo 13 inches losg. C, the whirl, 
 wherein a small worsted band from the cylinder H, fig. 444, works D, a 
 convex seat upon the spindle, whereon the concave bottom of the bobbin or 
 quill E rests.' 
 
 F, a piece of buffalo skin or metal screwed or nailed to the rail I, having 
 a hole in it, through which the spindle passes, and by which it is kept 
 steady ; G, a wire bent at right angles at a, and the bent part driven into 
 the rail A, so that it may be removed to or from the whirl C, and by the 
 other crook, b, prevent the spindle from running out of its step H, which is 
 a screw of brass or other metal passing through the rail K. The wire of 
 which the holder is made, after forming the elliptical eye, is left or extended 
 beyond the uppermost part at e, that the yarn may be conveniently slipped 
 in when occasion may require it ; these holders for each thread are for the 
 purposes of keeping the yam in a state nearly vertical over the tops of the 
 spindles when the carriage which contains them is coming out, and being re- 
 leased from that situation at the beginning of the carriage’s return, and thrown 
 into nearly a horizontal position, so as to bring the yarn below the top ot 
 the bobbins or quills upon the spindles ; and then being curved and raised 
 again by the wheel U, and its cylindrical roller moving upon the plane W 
 and X, fig. 444, distributes the yarn upon the bobbins or quills, and pre- 
 vents it from cockling, hinkling, or improperly doubling or twisting together. 
 The seats upon the spindles described by D, are turned convex, and the 
 bottoms of the bobbins and the bottoms of the quills concave, to keep the 
 bobbins or quills in a more central state upon the seats. The concavity of 
 the bobbins or quills exceeding the convexity, throws the weight of the 
 bobbins or quills upon the peripheries or extremities of the seats, and 
 ensures the rotary motions of the bobbins or quills with that of their 
 spindles. We prefer the convex and concave surfaces before described; 
 but other surfaces will have nearly the same eftect, if so contrived (as they 
 easily may be) to bear upon the peripheries or extremities of the seats as well 
 as of the bobbins or quills. The hole through the bobbin or quill, fig. 446, 
 is rather larger than the spindle, that it may not be obstructed in its motion 
 round the spindle, which motion takes place at every return of the carriage, 
 and as often as any thing obstructs the coming forward of the sliver of 
 which the yarn is formed. At one end of the arbor whereon the holders 
 are fixed is a counterpoise L, fig. 443, having a socket, and made last ; 
 
AND MACHINIST. 
 
 409 
 
 the arbor by a thumb-screw wi, the round ball at the top being led to 
 counterbalance the holders. This counterpoise, when the holders are in a 
 vertical state, declines about 10 or 15 degrees towards the horizon, but 
 when the holders are thrown down, and under the government of the cylin- 
 drical roller V, upon the wheel U, is in a different situation ; but the roller 
 V, arriving at B 3, fig. 444, on the return of the carriage, the holders are 
 precipitated to a height where the counterpoise overbalances them, and 
 locks the wheel M, fig. 443, or U, in fig. 444, in the ratchet n, where it 
 remains until the carriage has reached its destined place, where the tail of 
 the catch O strikes against a pin in the frame C C C C, fig. 444, and 
 releases it, the said roller then resting upon the frame U X. A second 
 method of compensating and providing for the want of elasticity in hemp 
 and flax, which is a part of the discovery, is, to fix a round bar of wood, 
 about inch in diameter, the whole length of the carriage, about three or 
 four inches above the tops of the spindles, so that the outer surface, or that 
 next the work-person, may be perpendicularly, or nearly so, over the tops 
 of the spindles, the inner side having pieces of w'ood or metal nailed or 
 otherwise fixed thereto, leaving only small spaces between each for the 
 yarn to pass through ; the use of these pieces is to prevent the threads 
 getting together and entangling, see fig. 447. A A A A represents a com- 
 mon faller used in the mule-jennies for spinning cotton with counterpoise B, 
 wheel C, with its cylindrical roller D, with the plane W and X, before 
 described by figs. 445, 444, and 443. E E, spindles with their whirls, con- 
 vex seats, bobbins or quills, with their concave bottoms, FF F F F F F F F F 
 the pieces of wood or metal, nailed or otherwise fastened to the round piece 
 of wood, to prevent the thread getting together. In this case every thing 
 applied to or used with the arbor, containing the holders above mentioned, 
 may be applied or used. 
 
 A third method of compensating the want of elasticity in hemp and flax, 
 which the patentees describe as a part of their contrivance, invention, and 
 discovery, is the fixing each spindle in a small frame A A, fig. 448 ; 
 b, a step of brass ; C, a common made spindle, with its whirl D ; E and F 
 two stil ts of iron fixed one on each side of the frame A A, equally in a line 
 •with the groove in the whirl D, and moving in holes in two cheeks g gy 
 fastened into the rail II, on the small frame A A. On the back side thereof, 
 next to the cylinder, is a small roller, moving on two pivots, so planted, 
 that when the spindle is in an upright position, the band from the cylinder 
 which drives it may just run free of it, and as the spindle frame, A A, is 
 kept to the rail I by a tender spring made of wire, wound round a pin 
 about half an inch in diameter, that the spindle may yield to the yarn in aH 
 cases when necessary, the said roller is to prevent the band which drives 
 the spindle out of the whirl, when the spindle leaves its vertical position. 
 
 Fig. 449, a side view of the little frame in fig, 448 ; A the frame, B the 
 spindle, C the whirl therein, D the end of the roller and one of its 
 supporters. This apparatus requires the faller last mentioned and described 
 by fig. 447, witli its appendages for laying the yarn upon the spindles, no 
 seat on the spindle or bobbin in this case being wanted, nor any more 
 than a thin piece of paper, or something thin, round the spindle, to enable 
 the spinner to take the yarn off with safety and care. A fourth and 
 last-mentioned mode of compensating and providing for the want of elasti- 
 cityin hemp and flax, and preventing breakages and other accidents from any 
 tightness in the yarn, occasioned by any obstruction or other circumstance, 
 and which is part of this invention and discovery, is, by driving the com- 
 mon mule-spindle with a slack band, having the yarn to pass over the 
 holders described in fig. 443, or over the round bar described in fig. 447, 
 
410 
 
 THE OPERATIVE MECHANIC 
 
 with all the other apparatus for laying the yarn upon the spindles, &c. 
 This last method cannot be used to advantage in any case, but may be 
 substituted for either of the three methods described above for spinning 
 yarn for sail clothe, sackings, tarpaulins, or other coarse or htnvy goods. 
 
 WEAVING. 
 
 In the preceding articles, cotton, wool, silk, and flax, we 
 have traced the process of forming the four commonest fibrous 
 materials to the state of thread or yarn, and now purpose, 
 in general terms, to treat of their farther destination in the 
 formation of the various superficial structures termed web or 
 cloth. 
 
 The structures which come under the name of cloth are 
 formed of two distinct layers of yarns, generally crossing each 
 other at right angles, termed the warp, and the woof or weft; 
 and as all cloths, however varied, are constructed of these 
 two distinct portions of threads, the mind will, when made 
 to comprehend the mode and form of loom used in the weav- 
 ing of one material, be able easily to conceive its application 
 to other sorts, varying only in dimensions and strength, 
 according as the weight of the yarn or size of the cloth may 
 demand. 
 
 Prior to commencing the weaving of any material, it is 
 necessary to prepare the yarn for the loom, one process of 
 which preparation is, in fact, the measuring and arranging 
 the threads that are to compose the warp in a parallel direc- 
 tion, termed luarping. 
 
 The warp, or that layer of threads which extends the length 
 of the piece to be woven, requires the most attention in the 
 preparation. To form a warp, it is necessary to be very 
 particular in the number and quality of the yarns ; for upon 
 their fineness, length, and breadth, depend the fineness, 
 length, and breadth of the piece to be woven. Though this 
 may appear a very simple operation, yet, the performing of 
 it with expedition and accuracy demands some mechanical 
 skill. The machine for effecting this object is termed the 
 warping-mill, and, though considerably larger, may be com- 
 pared to the reel described in the cotton manufacture : but 
 the spindle upon which it revolves is placed perpendicularly. 
 The reel cannot easily be made of such dimensions that a 
 thread measured upon its circumference shall be equal to the 
 required length of the warp ; and consequently the layer of 
 yarns is placed in a direction parallel to the axis of the reel, 
 
AND MACHINIST. 
 
 411 
 
 and wound upon it in a spiral direction till they arrive at the 
 upper end, when the motions of the mill and the yarns are 
 reversed, and a fresh layer is placed upon the same parts of 
 the reel. By this method of plying the layers of yarn, it is 
 obvious, that a small number of ends may be doubled so as 
 to form the required breadth of the w’ai*p. If the twist is 
 spun on cops, it must, prior to warping, be wound on bobbins, 
 which bobbins are placed in a frame to be wound off upon 
 the warping-mill. 
 
 The next operation to be effected in the manufacture of 
 cotton goods is that of dressing the warp ; that is, impreg- 
 nating it with certain gummy or gelatinous matter, and coating 
 the surface of the yarns, to enable the warp to sustain the 
 abrasion to which it is subjected in the process of weaving, 
 as will be seen when that process is described. In preparing 
 the wool and silk yarns for the looms, dressing is in general 
 only required for the finest sort, when a little mucilage of 
 gum arabic, or of jelly made from rabbit or other light skins,' 
 is used to increase in a slight degree the tenacity. 
 
 As it is of considerable importance in the dressing of warps 
 to have the materials dispersed equally over the surfaces, 
 many ingenious mechanics have constructed machines for that 
 purpose ; the general principle of which are the placing of 
 the warp on a roller, and immersing it in the mucilage, 
 which allows it to be drawn off covered with mucilaginous 
 matter. The superfluous mucilage is brushed off, and the 
 yarn is put in a frame, and by means of revolving fans is 
 dried and rendered fit to be put in the loom. In cases 
 'where the manufacturer operates separately, the weaver 
 dresses the warp, by extending and carefully brushing it over 
 with paste, and drying it in the air, prior to placing it in the 
 loom. 
 
 Before we proceed to give a description of the looms used 
 in the manufacture of cloth, it is requisite that the reader 
 should be acquainted with the various sorts of structure arising 
 from the dift'erent dispositions of the warp and weft, termed 
 fabric. 
 
 The simplest mode of disposing of the warp and weft is 
 called common fabric ; and taking into account the quantity 
 of yarn used for a given superficies of cloth, is certainly, 
 so far as respects its strength and durability, the most advan- 
 tageous mode of distributing it. 
 
 Fig. 412 is a section of a piece of cloth wove in the common fabric. 
 The circles represent the warp in section, and the weft is seen passing 
 alternately above and below each succeeding yarn, and the return, or next 
 
412 
 
 THE OPERATIVE MECHANIC 
 
 layer of weft, passing beneath those threads over which it had passed before, 
 and vice versa. 
 
 Fig. 413 represents a section of a piece of cloth wove to a twilled 
 pattern. In this the yam of the weft passes alternately over four and 
 under one of the threads of the warp, and vice versa in its return. 
 
 Fig. 414 represents the section of a dimity or kerseymere, in which the 
 weft passes over four and under four, then over one and under four, and 
 over four and under one, which places it in a position to begin again ; when 
 the passage of the weft, as it regards the warp, is exactly reversed. 
 
 Fig. 415 shows the construction of a double cloth woven with two warps. 
 This mode of weaving is mostly applied to the construction of carpets, and 
 the transposition of the colours in the pattern arises from it. All the divers 
 modes of passing the weft among the warp may be introduced in this 
 figure, and whatever is effected with one web of warp is alternately effected 
 with the other, as may be seen by the figure. It is therefore easy to 
 conceive, that all the various patterns in woven goods are obtained by 
 differently disposing of the warp, that is, lifting a greater or smaller quan- 
 tity of it at a time, which places the weft on either surface of the cloth at 
 pleasure. 
 
 The common loom, or that which is destined to w'eave cloth of the 
 common fabric, is the most simple in its construction, as the mode of lifting 
 and depressing the portions of the warp are similar at each throw of the 
 shuttle. A top view of a loom of this description is given in fig, 416. 
 
 A is a warp. 
 
 B a roller upon which the warp is wound, called the yarn-beam, and 
 applied to maintain the w^arp in a stretched position by means of a lever 
 passing through one of its ends and tightened with a string, as will be 
 more clearly understood by referring to the perpendicular section at No. 2 
 of this figure. 
 
 C C C are rods placed between the threads of the warp to keep them 
 separate, so that they may pass forward clear of each other, when the 
 warp is fed forward and filled with the weft, these rods are at different 
 periods moved towards the warp-roller B. 
 
 At D are the heald or heddles, formed of two rods, one above and the 
 other below the piece, and connected together by numerous strings, 
 through which distinct portions of the warp pass, and by means of the 
 treadles below are lifted and depressed. A detached view of two leaves of 
 a heddleis represented in section in fig. 417. 
 
 a a, a* a’, are the top and bottom bars, and the two lines a'* a'^ represent 
 two adjacent yarns of the warp, so that when a a rises it carries with it 
 one thread, while the other thread which is passed through the lower loop 
 of this heddle is depressed by the other heddles. The next part, E, fig. 416, 
 is a frame to carry the reed, called the lay. A portion of the reed is shown 
 detached in fig. 418. It is, except when used in cloth of the coarsest 
 description, formed of flatted wires, placed parallel to each other, and 
 governed, as to their thickness and adjacency, by the fineness of the fabric 
 in which they are to be used. 
 
 The lay, %. 416, which carries the reed, is hung from a bar capable of 
 vibrating on gudgeons in the upper frame of the loom. The two thin 
 elastic pieces of wood which suspend the lay are called swords, and may be 
 seen at F\ F^, fig. 419. The r^ed thus hung is just beyond the line of the 
 shuttle-flight, and has one or two threads of the warp passed between each 
 of its wires, which wires are termed dents. Its use is to strike home the 
 thread of the weft immediately after it has been delivered by the flight of 
 the shuttle ; it is therefore pushed by the weaver towards the yarn-beam, 
 
/■'rom /17 to 423 
 
 TL. 68 
 
AND MACHINIST. 413 
 
 prior to each flight oi’ the shuttle, and when the weft has been delivered, it 
 IS allowed to return and strike home that individual thread. 
 
 The next part of the loom is the shuttle-boxes, which are placed at F, F. 
 In weaving narrow goods, the shuttle is passed between the warp by the 
 hands of the weaver, but when the cloth is fine, or of a breadth to preclude 
 this mode, the fly-shuttle, which is much more compact, and has a spindle 
 to carry a cop upon it, is introduced. This form of shuttle is represented 
 in fig. 420. The shuttle with its cop is placed in the shuttle-box, which is 
 of dimensions just sufficient to receive it. In fig. 419 is represented the 
 reed and lay at F^ F^. The shuttle is driven to the opposite boxes by 
 means of a small piece of wood, called a driver, which lies behind the 
 shuttle in each box, and is capalale of being swiftly drawn forward by a 
 string attached to it, and connected with a handle, G. The weaver holds 
 the handle in his hand, and by a jerk throws the shuttle across the web 
 into the opposite box, and then, by bringing the lay towards him, strikes 
 home the weft. The flight of the shuttle requires adjustment or skill, as 
 its impetus must be proportioned to the weight of the yarn which it carries, 
 and the freedom with which the cop unwinds. 
 
 If two or three colours of weft are to be put into a piece, so as to form a 
 pattern, there are two or three shuttles to be thrown ; in such case, the 
 shuttle-boxes are formed in three parts, as represented by the dotted lines. 
 This combination of shuttle-boxes is capable of being moved upwards and 
 downwards upon the lay by the small levers, II, H, fixed upon the swords, 
 .and worked by the handle I, so that the shuttle to be thrown may be 
 brought opposite to the division in the w^arp through w'hich it is to fly. 
 
 As the cloth is perfected, it is led over the breast-beam K, fig. 416, and 
 is, by means of a ratchet wheel, wound upon the roller L, which is termed 
 the cloth-beam. At m is a stretching-rod, formed of two pieces, and lashed 
 with a piece of band, in such manner, that the ends are forced outwards, 
 as may be seen in the figure. This rod has small points at each end, which 
 pass through the selvage of the cloth, and serve to keep the cloth stretched, 
 as otherwise the action of the weft would occasion it to pucker and lay in 
 hollows. The weaver sits behind the breast-beam, and in fine work, 
 where the breast-beam is dispensed with, behind the cloth-roller. 
 
 Such is the construction of loom used in plain- weaving; 
 and by examining it attentively it will be seen, that by an 
 additional number of heddles any required movements of the 
 warp can be effected, and by varieties of weft other diversifi- 
 cations attained almost to infinity. The greatest skill required 
 in the act of weaving by hand is the directing of the flight of 
 the shuttle, where the impetus given should just suffice to 
 deliver it in the opposite box. The striking home of the 
 weft should be done with a regular force, and the preparatory 
 operations carefully attended to, that the warp may wind off 
 freely and regularly with an equal tension in all its parts. 
 
 From an examination of the movements of so simple a 
 machine as the loom, the mechanist will instantly conceive 
 the practicability of applying power to produce the necessary 
 movements ; we shall, therefore, present the reader with two 
 combinations of this class which are called power-looms: 
 the first invented by a Mr. Millar. 
 
414 
 
 TilE OPERATIVE MECHANIC 
 
 Fig. 421 represents a section of a power-loom, in which all the operations 
 are effected by means of treadles, moved by wipers or eccentrics. 
 
 A, the main shaft, to which the power is communicated, carrying the 
 wipers, one of which is seen at A. A', the yarn-beam ; B, three rollers, on 
 the lower of which the cloth is wound after passing above and between the 
 two upper ones ; C, C, tlie heddles ; D, D, the treadles, to which the heddles 
 are attached by means of a line passing over a pulley, in such manner, that 
 tne depression of one heddle occasions the raising of the other ; E, E, the 
 lay carrying the reed ; the motion is given to the lay by a wiper moving a 
 treadle that is attached to the lay by means of the line and crank at 
 F. The return motion for striking home the weft is given by a weight 
 hanging over a pulley, as may be seen in the figure. The flight of 
 the shuttle is occasioned by attaching the strings from the drivers to 
 another treadle, which treadle is worked at the proper periods by another 
 wiper. 
 
 Another form of power-loom^ called the crank-loom, is 
 used, and varies from the preceding in the mode by which 
 the movement is given to the heddles. In this construction 
 of loom the revolving shaft is placed immediately under the 
 heddles, which are suspended over a pulley similarly to the 
 loom last described; but the motion is given to them by 
 means of their being attached to two opposite cranks on the 
 shaft. The motion is given to the lay by a crank upon ano- 
 ther shaft, which is made to revolve twice, while the shaft 
 that moves the heddles revolves once. By this, it is evident, 
 that the warp is opened, and the shuttle thrown twice, during 
 one revolution of the first shaft. 
 
 The flight is given to the shuttle by the cords of the drivers being attached 
 to an upright lever, as represented in fig. 422. 
 
 The cords, c, c, of the drivers are attached to the lever, e, which, by 
 means of the arms, /i, i, is caused to vibrate in opposite directions upon 
 the centre, being alternately struck, by two projecting pieces upon the 
 first mentioned crank-shaft, which causes the lever, c, to vibrate in a plane 
 parallel to the crank-shafts, and gives flight to the shuttle, at the period 
 when the warp is opened. 
 
 In either of these plans for working looms by power, if the 
 number of heddles is required to be increased, in order to 
 produce any figure, it is easily effected, by varying the 
 number and the position of the cranks or wipers. 
 
 But, though great variations in the movements of a warp 
 may be effected by using many heddles, yet when the number 
 of heddles and the number of cranks are increased, great 
 objections arise to their being used; consequently, ano- 
 ther construction of loom, called the draw-loom, is intro- 
 duced when complicated figures are to be woven. In this 
 loom the changes are effected by raising one portion of the 
 warp entirely out of the way, wdiile the other is wrought by 
 the heddles at the time it is being filled with the weft; the 
 
AND MACHINIST. 
 
 415 
 
 part raised is then lowered into work, and other yams of the 
 warp lifted out of the way, 
 
 A loom on this principle is shown in fig. 423. For weaving carpets by 
 this method, every yarn of the warp has a line attached to it, which lines 
 are brought together in one connected piece, according to the portion of 
 warp to be raised at once, and carried over the pulleys as at A, and attached 
 to the fixed beam at B. This portion is called the tail. Below the warp 
 these lines, which are called the simples, are kept in a state of tension by 
 weights, as at C ; and in order to keep them distinctly apart, are made to 
 pass through a board perforated with holes at D. Other lines are attached 
 to the tail, capable of being pulled by handles, as at E, by which means,, 
 such portions of the warp as are required can be raised. By this contriv- 
 ance the greatest intricacy of pattern can be attained ; but the attaching of 
 the simples to the different parts of the warp, by means of small eyes of 
 metal through which the threads of the warp are made to pass, is a work of 
 considerable labour. Damask table-cloths are produced by this loom. 
 
 It would occupy too much room were we to enter with 
 more exactness into the great variety of looms which ingenuity 
 has constructed ; what we have said therefore we trust will be 
 sufficient to convey to the reader a perfect knowledge of the 
 principles of forming those various fabrics which are termed 
 cloth. In the weaving of ribands and other ornamental 
 works, many extraneous substances, totally unconnected with 
 the warp or weft, are thrown in, which affords the designers 
 an additional scope for the display of embellishments. These 
 substances are merely held in the fabric by the intersection 
 of the two staple parts, the warp and the weft, and are by 
 the weavers denominated whips. 
 
 In the formation of cloth from the yarn of cotton, silk, 
 hemp, and long wool, denominated worsted, the fabric when 
 taken from the loom is, so far as regards the weaving, in a 
 perfect state ; the further operations, both mechanical and 
 chemical, which it undergoes, may properly be considered as 
 tending merely to its further embellishment. These opera- 
 tions consist generally of singing the superfluous fibres from 
 the surface of the cloth, by drawing it over hot irons, and 
 after bleaching or dying, submitting the cotton and linen 
 goods to pressure between heavy iron cylinders, for the pur- 
 pose of giving it a gloss, and the worsted, called camblets or 
 stuffs, between warm copper-plates, called hot-pressing, to 
 give it a smooth and finished appearance. 
 
 In the formation of cloth from short wool, of which our 
 wearing apparel is made, the loom cannot be said similarly 
 to have completed the operation. In this branch of manu- 
 facture, the yarn is woven in a common loom in the manner 
 we have shown, and called common fabric, but .when the 
 piece is taken from the loom the web is too loose and open. 
 
416 
 
 THE OPERATIVE MECHANIC 
 
 and is consequently submitted to another operation, called 
 fulling. The cloth, after it is, by repeated washings, divested 
 of the oil that was put in it in the act of carding the wool, 
 is taken to the fidling-mill, where it is immersed in water, 
 and subjected to repeated compressions by the action of a 
 large beater formed of wood, which repeatedly changes the 
 position of the cloth, and by its continuous action causes the 
 fibres to felt and combine more closely together, so that the 
 beauty and stability of the texture is greatly improved. The 
 cloth is next submitted to the dyer, if so destined ; but in 
 many colours for the best cloths this process is effected in 
 the wool prior to the commencement of the manufacturing. 
 
 The cloth then undergoes the operation of the gig-mill, 
 which is formed of a cylinder, somewhat similar to that of 
 a carding-engine, covered with the heads or burs of a large 
 species of thistle, called teasels. This engine is used to 
 raise the fibres or nap, and lay it in a parallel direction, 
 which, in fine cloth, is cut off by shears, and the cloth 
 then undergoes hot-pressing to bring it into a state fit for the 
 market. 
 
 Upon considering the various methods of fabricating cloth 
 in general, it may easily be conceived, that great scope is 
 afforded to the practice of dishonest modes of forming fabric 
 apparently valuable, such as the introducing of weft or warps 
 of different qualities and hiding them by the mode of plying 
 the other part. In trying the strength of cloth it should 
 always stand both in the direction of the warp and the weft; 
 and the substances of which all parts are formed should be 
 known by separate examination, and not by mere superficial 
 inspection, as the surface may easily be formed to hide 
 defects, and display apparent value. 
 
 ROPE-Mx\KING. 
 
 In rendering the hemp-plant proper for the uses of the 
 rope-maker, it has to undergo a variety of processes. 
 
 The first of these is retting, that is, exposing it to me 
 action of the dew, or w^ater ; the former termed deiv-retting ; 
 the latter, by which the finest hemp is produced, water- 
 retting. In both or either of these processes, the quality of 
 the hemp is said to be influenced by the state of tbe weather, 
 and the finest to be produced when showers have mostly 
 prevailed. 
 
and machinist. 
 
 417 
 
 In dew-retting^ the hemp-stalks, immediately after being 
 pulled, are spread out, in a thin, even, and regular way, so 
 us to keep exact rows, on a fine level piece of close old sward 
 land, for the space of three, six, and sometimes eight weeks, 
 as circumstances may require ; during which, they are turned 
 two or three times in the week, according to the state of 
 the atmosphere. 
 
 The motive for thus spreading it out upon the ground is, 
 that the dew, by penetrating into the plant, may render the 
 separation of the rind from the stem or bur easy to be 
 accomplished. When the dew has acted upon it sufficiently 
 for this purpose, it is tied up into large bundles, and carried 
 home and slacked, or otherwise it is put into a covered 
 building, till wanted to be formed into hemp. 
 
 This process, called grassing^ requires great nicety and 
 attention, that the texture of the hemp may not be injured 
 either by too long continuance on the sward, or by being 
 removed before the hempy substance is rendered sufficiently 
 separable. 
 
 In water -retting, the much more common and speedy 
 method is, to tie the hemp-plant into small bundles, by 
 means of bands at each end, and in general to deposit it 
 bundle upon bundle, in a direct and crossing manner, in a 
 pond of standing water, to form what is called a bed of 
 hemp. This bed, when formed of as great a thickness as the 
 depth of the water wdll admit, wdiich some think can hardly 
 be too great, though five or six feet are the usual depths, is 
 loaded with large pieces of heavy wood until the whole is 
 immersed in the water. In choosing ponds, those should be 
 preferred that have clayey bottoms. 
 
 When the hemp-plant has remained in the water for about 
 five or six days, varied according to the nature of the pond 
 and the state of the weather, it is taken out, and conveyed 
 to a piece of mowm grass or other sward land, which is free 
 from all sorts of animals. Here the bundles are untied, and 
 the hemp-stalks spread out thin, stem by stem. While in 
 this state, especially in moist weather, they must be carefully 
 turned every second day, to prevent their being injured by 
 the worm casts. In this way they are kept for about five or six 
 weeks, when they are gathered up, tied in large bundles, and 
 kept perfectly dry in a house or small stack, till wanted for use. 
 
 In some of the northern parts of Scotland, the hemp, after 
 it has been pulled, and cleared of its leaves, seeds, and 
 branches, by means of a ripple, is formed into bundles of 
 twelve handfuls each, and steeped in a manner similar to flax, 
 
 2e 
 
418 
 
 THK OFERATIVS MECHANIC 
 
 till its reed becomes capable of parting from the barlu In 
 this process^ it is favourable to give it rather too much than 
 too little of time ; and let it be observed^ that the most 
 slender hemp requires the greatest length of time in the 
 water. Where the quantity of hemp is only small, the 
 hempy part may be separated from the reed by hand-labour; 
 hut where it is large, drying and breaking it in the manner 
 of flax is strongly recommended. 
 
 After the hemp has been taken out of the water, it is not 
 spread out upon the grass-ground in the way of flax; but 
 set up in an inclined position against cords arranged for 
 the purpose, or by any other method by which it can receive 
 the full benefit of the air till it be perfectly dried, which may 
 be known by its rising in blisters from the boon. As soon 
 as it has been reeded, it must be divested ©f the mucilaginous 
 material which it contains, by pouring water upon and re- 
 ])eatedly squeezing it. In this part of the process great care 
 must be taken to prevent the fibres from getting entangled, 
 as by that means great waste will be incurred. 
 
 M. Brealle, on the Continent, has suggested a mode, very 
 different to any of these, for the purpose of steeping hemp, 
 the advantages of which, it is asserted, have been fully proved 
 by numerous trials. The process consists in heating water 
 in a vessel, or vat, to the temperature of from 72 to 'Jb 
 degrees of Reaumer, and dissolving in it a quantity of green 
 soap, in the proportion of 1 to 48 of the hemp : the body of 
 the water being about forty times the weight of the hemp. 
 When this preparation is made, the hemp is thrown into it, 
 and floats on the surface, and the vessel being immediately 
 covered, the fire is put out. In this state the hemp.is allowed 
 to remain for two hours, at the expiration of which time it 
 will be found to be fully steeped. 
 
 The principal superiority of this method, besides the great 
 saving of time and expense, is said to consist in the hemp 
 affording a greater proportion of tow. The value of the 
 fuel, as v/ell as the time employed in the process, should, 
 however, be well considered in such cases. Besides these, 
 it is said to promote the cultivation of tlie hemp crops, by the 
 facility which it affords to the preparation, even in such 
 situations as are not contiguous to rivers, streams, or ponds ; 
 it also obviates any ill consequences that might possibly 
 ensue from the putrid effluvia of the atmosphere, and the 
 corruption of the waters, induced by it, which last are well 
 known to destroy the fish contained in them, as also to prove 
 hurtful to the cattle that drink of them. 
 
AND MACHINIST. 
 
 419 
 
 In consequence of the great trouble and expense attendant 
 iipon the process of water-retting, the hemp is frequently left 
 for seed; in which case, it is commonly stacked up and well 
 covered for the winter season, in order that it may be thinly 
 spread out in about January or the following month. Where 
 this can be executed during the period of a snow, the hemp 
 comes much more readily to a good colour, and forms strong 
 coarse cloths ; but it is far inferior to that pulled in due season, 
 and .which has undergone the water-retting operation. 
 
 Various contrivances have been made in the form of ponds 
 and pits, for the steeping of hemp ; but the one which seems 
 to possess the most merit is described in the Norfolk Report, 
 as the invention of Mr. Rainbeard ; by using of which, the 
 hemp can be deposited in the pit, without the necessity of 
 any person getting wet. The pond is an old marl-pit, 
 with a regular slope from one side, where the hemp is pre- 
 pared, to the depth of eight feet on the other side. On the 
 slope, above the water, the hemp is built into a square stack 
 upon a frame of timber, of such a height as will float and 
 bear a man without wetting his feet : this is slid down upon 
 the frame into the water, and a person on the opposite bank 
 draws it to the spot where it is to be sunk. Mr. Rainbeard 
 has found by experience, that the hemp does soonest at the 
 bottom, and would not object to 16 feet of water. By 
 means of this very useful contrivance he can put in a waggon- 
 load in an hour. The sheaves are taken out one by one in 
 the usual way ; but it is suggested, that some more expedi- 
 tious and simple contrivance, either upon the principle of 
 the lever, or some other, should be resorted to, for effecting 
 the desired purpose. 
 
 In preparing the hemp for the hackle, the work is executed 
 chiefly by the beetle, first using a coarse, and then a finer 
 brake : it may, however, be more expeditiously performed by 
 the rollers of a lint-mill. In either mode, shaking the hand- 
 fuls frequently with force is necessary. In cases where the 
 plant has not been sufficiently watered to loosen the rind, the 
 operation of peeling must be performed by the hand. 
 
 Another method for effecting this purpose is the hemp- 
 mill, which is much used in America. It consists simply of 
 a large heavy stone in the form of a sugar-loaf, having the 
 small end cut off. Thus shaped, it readily moves round 
 in a circle, when passing upon a plane. The motion is 
 given by the impulse of water on a wheel, and the hemp, 
 deposited on the receiving floor of the mill, is, by the weight 
 and revolutions of the stone, perfectly crushed and broken. 
 
TUB OPERATIVE MECHANIC 
 
 420 
 
 Still, however, the fluted rollers of a lint-mill are the best 
 means of performing the work, provided sufficient care be 
 taken to guard against accidents. 
 
 When the hemp has been completely broken, it is sub- 
 mitted to another operation, called swingling, or scotching ; 
 the intention of which is, to separate the reed from the 
 hemp. This operation is sometimes performed by a labourer, 
 who takes a handful of hemp in his left hand, and while 
 holding it over the sharp edge of a board, strikes it with, the 
 fine edge of a long flat straight piece of wood, usually termed 
 a swingle-hand or scotcher 5 but this way is both laborious 
 and tedious, consequently, mills moved by water, having a 
 number of scotchers fixed upon the same axle-tree, and mov- 
 ing with great velocity, are much more frequently used. The 
 work, in this case, is executed with much greater expedition, 
 and far less fatigue of the workman ; but the velocity of the 
 mill occasions a great waste of hemp. 
 
 Before the hemp prepared in this manner is subjected to 
 the hackle, it mostly undergoes another process, termed 
 beetling; by which the fibres of the hemp become more 
 loosened and divided. The beetles employed with this 
 intention are moved by the power either of the hand or 
 water, which may be considered best. 
 
 The implements used in preparing hemp for the operation 
 of spinning are so very similar to those described in the 
 preparatory processes of the flax-manufacture, that we do 
 not consider it necessary to give more than a general descrip- 
 tion of the proeesses ; we shall therefore conclude this article 
 with an accurate description of a patent, taken out by 
 Mr. George Duncan, of Liverpool, in March 1813, for his 
 improvements in the different stages of rope-making, and 
 for certain machines adapted for the same. 
 
 The first part of the process which he has described, is 
 that for spinning the yarn for all kinds of cordage, lines, 
 and tivine. 
 
 In this part of the invention there are two railw’ays, 
 adjoining and parallel with each other, fixed along the spin- 
 ning-ground or rope-walk, from one end of it to the other. 
 Upon each of these railways a machine for spinning the 
 yarn is made to travel alternately backwards and forwards, 
 one setting ofl from the bottom of the ground at the same 
 lime that the other sets off from the top, and as they both 
 travel at the same rate, the former arrives at the top of the 
 ground at the same time the latter arrives at the bottom. 
 
 These spinning-machines are in every respect similar to 
 
AND MACHINIST. 
 
 421 
 
 each other, and are respectively furnished with two sets of 
 twisting spindles ; one set being placed at one end of the 
 machine, with the hooks facing the top of the spinning- 
 ground ; the other at the opposite end, with the hooks 
 facing the bottom. The spinners employed in spinning with 
 them are, accordingly, divided into two companies, and 
 arranged similar to the machines ; the one company at 
 the top, the other at the bottom, of the ground. The number 
 of spindles in each set of each machine should be equal, and 
 also equal with, or rather not fewer than, the number of 
 spinners in each company ; or, in other words, as there are 
 in each machine two equal sets of spindles, (four sets in all,) 
 the number of separate spindles in the two machines should 
 not be fewer than double the whole number of spinners 
 employed ; because one set only in each machine is occupied 
 at the same time in spinning, the other set being in the 
 mean time engaged in retaining the yarns last spun from it, 
 and following them back to the winding-machine. 
 
 The manner in which the operation is performed is as 
 follows: — The spinning-machines are placed, as before de- 
 scribed, one at each end of the spinning-ground, on its respec- 
 tive railway, ready to set off. Each spinner of the two 
 companies immediately attaches his hemp or flax to the 
 spindle of the machine that is nearest to him •, and the motions 
 of both machines, excepting those of that set of twisting- 
 spindles facing the opposite company, are then struck into 
 geer, and each machine recedes from its own company, spin- 
 ning and leaving the yarn on separate guides or hooks as it 
 proceeds onwards, the one down and tlie other up the ground, 
 the one arriving and striking itself out of motion at the 
 bottom, when the other arrives and strikes itself out of motion 
 at the top. Each spinner of the two companies then detaches 
 the yarn in his hand from the hemp or flax which he was 
 spinning, and fixes the end of the piece that is spun to a 
 v/inding-up reel, in a machine stationed behind or near him, 
 while the other end still remains attached to the spindle-hook 
 of the machine on which it was spun, and which is now at 
 the further end of the ground. 
 
 The machines have now changed their company ; that is, 
 the machine which formerly belonged to the company at the 
 top, now belongs to the company at the bottom ; and that 
 which belonged to the company at the bottom, belongs now 
 to the company at the top. Each spinner, therefore, of both 
 companies, immediately attaches his hemp or flax to the 
 spindles left vacant by the opposite company, and the fHotions 
 
422 
 
 THE OPERATIVE MECHANIC 
 
 of the spindles to which the hemp or flax is attached being 
 struck into geer^ the spinning proceeds as before ; during 
 which, the respective winding-machines wind up the yarns 
 last spun, regularly as the spinning-machine, to whose spin- 
 dles they are attached, and which have remained stationary, 
 advances towards it from the other end. 
 
 The spinning of the two sets of yarn, and winding up of 
 the two last spun, being finished at one and the same time, 
 the whole machinery again stops, and each spinner, as before, 
 immediately detaches the yarn in his hand from the hemp or 
 flax, and then detaches from one of the spindle-hooks of the 
 spinning-machine just arrived, the yarn which he had on the 
 former occasion spun, and which has just been wound up on 
 one of the reels of the winding-machine, as closely as the 
 short length necessarily intervening between the spinning and 
 winding machines will allow. The two ends of these yarns 
 he splices together, so that the yarn just spun, lying on the 
 guides or hooks along the whole length of the spinning- 
 ground, is now ready to be wound up. The spinners then attach 
 their hemp to the emptied hooks, the machines are again 
 struck into motion, the spinning and winding go on as before, 
 and the same procedure continues to be renewed each time. 
 
 The general principle which constitutes this mode of opera- 
 tion, and consequent facilities of the invention, are, that one 
 set of spindles in each machine is always employed in spin- 
 ning, while the yarns spun by and attached to the hooks of 
 the other set at the opposite end of the machine are Avinding 
 up, so that every spinner is constantly kept at work in spin- 
 ning, excepting the short interval when splicing the yarn, 
 and preparing to set on to spin. Throughout the whole of 
 the operation, therefore, whatever one of the spinning and 
 the winding machines may be performing, and one of the 
 company of spinners employed in doing, the other spinning 
 and winding machines, and company of spinners, are, in 
 every respect, similarly engaged. 
 
 An endless rope, driven by any external machinery, gives the 
 travelling and twisting motions to both spinning-machines ; 
 and the whole of these motions are connected with and bear 
 a given proportion to each other, capable of being regulated 
 to suit the speed required. The two winding-machines may 
 also be driven by the endless rope. All or any of these 
 machines may, nevertheless, be driven by distinct endless 
 ropes, or by any other method or methods in use for driving 
 locomotive machinery, provided the proportionate speed be 
 kept up. 
 
AND MACHINIST. 
 
 423 
 
 The application of the rack, hereafter described, will be 
 the most accurate for regulating the travelling-movement of 
 the spinning or any other machine, on a rope-walk ; but as 
 the resistance in the present case is very trifling, the motion 
 given to the truck-wheels of the spinning-machine, as shown in 
 the engravings, will answer the purpose at less expense. 
 
 As a further improvement, Mr. Duncan invented an addi- 
 tional apparatus for giving an after-twist, which either may 
 or may not be adopted. The object of this improvement is, 
 to prevent the yarns losing strength, which otherwise they 
 do, by losing twist by the counter-twist of the strand, and 
 other subsequent operations. This is effected in a simple 
 and convenient way, by continuing the twisting for a sufficient 
 length of time after the travelling motion of the spinning- 
 machine has ceased ; by which means, an additional twist is 
 given to the yarns after they are spun to their full length ; 
 and this is done while the spinners are splicing them at the 
 other end of the spinning-ground, and preparing again to set 
 on to spin, without occupying any of their time for the pur- 
 pose. The effect of this part of the invention for the after- 
 twist has been produced in different ways by others ; but by 
 modes either so complicated or expensive, as not to be con- 
 veniently available in practice. 
 
 The principal advantages to be derived from this method 
 of spinning are the following : 
 
 First. The spinners are enabled, at much less expense, to 
 spin a greater quantity of hand- spun yarn than they can by 
 any other method in the same space of time ; because, except 
 while splicing the threads, they are constantly occupied in 
 spinning ; and have neither to hook up the threads, nor to 
 travel up and down the walk, so that their time and attention 
 is solely confined to the delivering of the hemp or flax from 
 their hands. Secondly. The speed of the spinning-machine, 
 besides being uniform, is proportioned to the full extent of 
 work the spinners can conveniently accomplish, which, in 
 some measure, compels them to produce the greatest possible 
 quantity ; and as the machine is constructed so as to lift the 
 threads off the hooks, and follow them up to the winding- 
 machine, little or no attendance is required from wheel-boys 
 or followers. Thirdly. The spinners are enabled, partly from 
 their wdiole skill and attention being confined to the one 
 object, of simply delivering the hemp or flax from their 
 fingers, and partly from the requisite degree of twist being 
 given by machinery, to produce a superior quality of yarn. 
 
424 
 
 THJC OPERATIVE MECHANIC 
 
 And fourthly. The hemp to be spUn by this machinery may 
 either be dressed in the usual way, or prepared and dressed 
 on the hackling-machines, which draw out the whole in a 
 long sliver ; and in either case it may be spun from the end 
 of the fibres, by which means the strongest yarn is formed. 
 It may, however, be spun from the spinner’s waist, and with 
 more convenience than in the common way, because, by this 
 method, the spinners remain always in a room at each end of 
 the spinning-ground ; consequently, the hemp is not so liable 
 to be discomposed as when they have to travel up and down 
 its whole length ; neither, for the same reason, is it so liable 
 to be wasted. 
 
 The expense attendant upon erecting the spinning ma- 
 chinery, with all its connections, and the power requisite to 
 drive it, is comparatively trifling. In making the spinning 
 machinery, various forms or shapes may be adopted, as they 
 may be made to travel on railways on the ground, or on 
 railways suspended from the beams of the rope-walk, or fixed 
 upon or above them, as may be thought proper ; and the 
 disposition of the necessary machinery may be arranged and 
 diversified to suit the situations of the railways, and the 
 construction and conveniences of the rope-walk. 
 
 llie mode shown in figs. 469, 470, and 471, is most preferred by 
 jMr. Duncan, merely because it occupies least room in proportion to the 
 number of spindles the spinning-machines can employ. The whole width 
 of a rope-walk, required by this mode, need not be more than six feet, except 
 at each end, where, of course, sufficient width convenient for the spinners, 
 and for the winding-machine and dressed hemp, must be allowed. In this 
 narrow space no less than twenty-four threads may be constantly kept 
 spinning at one time, and as many winding up ; so that besides every other 
 advantage, the saving in the original cost of a spinning-ground on this plan, 
 and in the expense of covering it in, will be considerable. 
 
 In the explanations to the figs. 478 and 479, is shown how other arrange- 
 ments may be made by which the competent mechanic will be enabled to 
 adapt or diversify the form of the machines, and form and disposition of 
 the machinery, to suit any situation in a ropery which is most convenient, 
 or of little use for other purposes. 
 
 In that part of the drawing, entitled “ Rope-spinning,’’ from A to B is 
 supposed to be the SYjinning-ground, shown as broken off in the middle, for 
 want of room to show it in full length ; C C and C C, on each side of the 
 break, is one railway ; DD and D L) the other. 
 
 Fig. 469 is a plan of one of the spinning-machines, at the top of the 
 ground, on the railway C C. 
 
 Fig. 470 is the other, exactly of the same construction, at the bottom of 
 the ground, on the railway D D ; and 
 
 Fig. 471 is a side elevation. 
 
 Tliough both machines are precisely similar, yet some parts of the 
 machinery are omitted in some of tl»c figures, tliat other parts may be seen 
 more distinctly, and in none of the figures are the whole shown together. 
 

 
 
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AND MACHINIST. 
 
 425 
 
 li, wherever ii occurs, shows the endless rope which drives both machines, 
 and IV the rollers or pullies suspended from the beams L over head, which 
 guide and carry it. 
 
 The same characters, in all the above figures, wherever they may be used, 
 denote the same part. 
 
 F shows the framing of the machines. 
 
 a and b two grooved sheeves, fastened upon the two upright shafts 
 c and d, (as best seen in fig. 471,) driven contrary ways by means of the 
 endless rope. 
 
 The manner in which the rope goes round, and grasps the sheeves, and 
 occasions their contrary motion, is best seen in fig. 470. 
 
 In fig. 471, e and / are two spur-wheels, fixed upon the shafts c and rf, 
 with a view to equalize their motion. 
 
 The twisting motions for each set of spindles are driven by their respec- 
 tive shafts, which, at the same time, drive all the travelling motions. But 
 the twisting motions for one end only are driven at a time; for while the 
 shaft that is nearest to the end from which the spinners are spinning, is 
 driving the twisting motions of that set of spindles, together with all the 
 travelling motions, the shaft nearest to the other end is not driving any, 
 though both shafts are then revolving. 
 
 g and h in the travelling motions are two pinions, upon loose rounds, 
 alternately driving the wheel i, which is fast upon the short upright shaft A, 
 and shown only in fig. 471. On the lower end of this shaft is the bevel- 
 wheel I, driving, by means of another bevel-wheel, m, the cross shaft w, upon 
 one end of which are fastened the sheeves 1,2, 3, and upon the other the 
 sheeves 4, 5, 6, seen best in fig. 469. These sheeves are of different sizes, 
 and one only at each end of the shaft is in use at a time ; o and p are the 
 two axles of the truck-wheels, having the sheeves 7, 8, 9, fastened upon o, 
 and upon/) the sheeves 10, 11, 12. The four truck- wheels 5^ are also fast- 
 ened upon the shafts 0 and p, and motion is given to them by two belts ; 
 one driven from any one of the sheeves 1, 2, 3, and the other from any one 
 of the sheeves 4, 5, 6, each belt running upon its corresponding sheeve on 
 the axles of the truck-wheel. The turning round of these axles impels, 
 according to the motion given to them, the machine forward ; which motion 
 can, by the sheeves being of different sizes, be regulated as occasion may 
 require. 
 
 On the lower end of the shafts c and d of the twisting motions are the 
 sheeves r and s, on loose rounds, each in its turn carried about by catch- 
 boxes, (as shall be hereafter explained,) and driving the upright rollers or 
 cylinders G and H, by means of belts going round the sheeves t and u, fast- 
 ened on the axles of the rollers. These hollers give motion to the twisting 
 spindles by separate bands or belts passing round a whirl on each spindle ; 
 in each machine are placed twenty-four spindles, twelve at each end, or six 
 at each corner of each end, the positions of which are seen in figs. 469 and 
 470. In either of these figures, one spindle at each of the four corners 
 only appears, the other five being ranged in a direct line underneath ; but 
 the manner in which they range is seen in fig. 471. In fig. 471, twelve, or 
 one half of the number of spindles, appear on the nearest side; six, or half 
 a set, at each end ; the other half appear similarly situated on the opposite 
 side. These two sets are alternately employed, the one in spinning, and 
 the other in holding and following the yarns that are winding up ; z 
 fig. 471, are ratchet-wheels and catches, placed on the axles of the rollers 
 G and H, to keep the yarns from untwisting when winding up. 
 
 Figs. 469 and 470 best show the carriers, projecting from the frame in 
 which the twisting spindles run ; the form and use of them, and of the 
 
426 
 
 THE OPERATIVE MECHANIC 
 
 whirls and spindles, are so obvious, that it is not necessary to point them 
 out in any of the figures by a distinguishing character of reference ; and, 
 for the same reason, none of the bands or belts are marked. 
 
 Having so far described the different motions and appurtenances of the 
 spinning-machine, we shall now proceed more particularly to explain the 
 manner in which they operate. 
 
 By an inspection of fig. 471, it will be seen, that the catch of the catch- 
 box 13 is in contact with the catch of the pinion h, and the catch of the 
 catch-box 14 with the catch of the sheeves I, and that the catches of the 
 boxes 1 5 and 1 6 are not in contact with the corresponding pinion g and 
 sheeve r. 
 
 17 and 18 are two separate levers, one at each end of the machine, 
 alternately used for striking into geer the catches above mentioned ; the 
 lever 17 serving for the two boxes 13 and 14, and the lever 18 for the two 
 boxes 15 and 16. 19 and 20 act as swingers or levers from the joints 21 
 
 and 22, having claw ends to grasp the catch-boxes 13 and 14 ; and being 
 coupled with the main lever 17, by means of the connecting rod 23, move 
 them either up or down. When in geer they are held firm by the sneck 24 ; 
 but on running against a fixture at one end of the spinning-ground, are 
 pulled back, which causes all the motions of the machine to stop. The 
 machine, however, may at any time be stopped, as occasion may require, by 
 pulling back the sneck by hand. The two main levers 17 and 18 are so 
 weighted at the handle end, that when disengaged from their snecks the 
 catch-boxes always fly out of geer. The machine is put in motion by raising 
 the main lever into the sneck by hand. All the machinery on each side of 
 the wheel i, at each end of the machine, is precisely alike ; the description 
 therefore given of one end may answer for the other. The twisting motions 
 at each end are never in geer at the same time ; for those at one end are 
 engaged in spinning one set of threads, while those at the other, whose 
 spindles retain and follow up the other set of threads (last spun) to the 
 winding-machine, remain at rest. All the four catch-boxes, 13, 14, 15, and 
 1 6, constantly go round with the shafts c and d, by means of feathers in the 
 shafts acting in grooves in the boxes. 
 
 When the catch-box 14 is in contact with the sheeve s, it gives motion 
 to the set of twisting-spindles belonging to the roller H, at the same time 
 its accompanying catch-box 13, by being in contact with the pinion h, 
 gives a retiring or travelling movement to the whole machine, which is 
 effected by the wheel i communicating motion to the four truck-wheels, by 
 the means which have been before described. The wheel i is common to 
 both pinions, being turned one way by one pinion, when the machine is 
 retiring from the top of the ground, and the contrary way by the other when 
 it is retiring from the bottom of the ground ; consequently, the cross shaft Ji, 
 which derives its motion from the wheel 2 , turns at the same time both the 
 truck-wheel axles, one way when retiring from the top, and the contrary 
 way wlien retiring from the bottom; the shaft n being common to both 
 truck -wheel axles. 
 
 Fig. 472 is the plan of a winding-machine, placed at the top of the spin- 
 ning-ground, containing twelve reels, corresponding with the number of 
 spindles in each spinning-machine. 
 
 Fig. 473 is a plan of a similar winding-machine, placed at the bottom ot 
 the ground, containing the same number of reels. Both these winding- 
 machines are mounted' so high above the ground as to allow the yarn wind- 
 ing on them to pass over head, that the spinners may have room to move 
 underneath. In the engraving they are placed rather nearer the spinning- 
 niachines than they ought to be, from want of room in the plate. When all 
 

AND MACHINIST. 
 
 427 
 
 the spindles of the two spinning-machines are employed, one half in spin- 
 ning and the other half in following up the yarns to the winding-machine, 
 as has already been described, all the reels of both winding-machines are of 
 course at the same time fully employed in winding up. 
 
 Fig. 474, at one end of the ground, shows a side view of the reels, placed 
 on their spindles, a description of which is unnecessary, as the movements 
 and construction of such machines are well known and understood. In the 
 figure they are represented as only winding one yarn on each reel, in ord-er 
 to expilain the improved or patent method of rope-making ; but more than 
 one yarn may be wound on any one of these, or any other kind of reel, that 
 may be used in my method of spinning, for the convenience of the common 
 method of rope-making, or for other purposes. It is neither convenient, nor 
 necessary, that the endless rope should cease motion, when the spinning- 
 machines have arrived and struck themselves out of geer at the top and bot- 
 tom of the ground ; consequently we will suppose, that the endless rope is in 
 motion, and all the other parts of the machinery at rest, excepting the two 
 shafts cand d, and their respective catch-boxes. The catch-boxes of each shaft 
 ill both machines are in the position of 15 and 16, as seen in fig. 471. Each 
 spinner in the two opposite companies having now attached the hemp to the 
 spindles, nothing remains to be done but to raise by hand the lever 1 7, 
 fig. 471, (which in the engraving appears to be already done,) and the corres- 
 ponding lever in the opposite machine ; which will cause the spinning and 
 winding to proceed in the manner already described. 
 
 When the machines stop, each spinner splices his thread, and throws it on 
 the nearest guide x, to keep it out of the way, and to conduct it to the wind- 
 ing-machine. The grooved sheeves a and b, on the top of tlie shafts c and d, 
 to which the endless rope gives the first motion, may be changed when re- 
 quired for sheeves of a larger or smaller diameter, for the pui’pose of dimi- 
 nishing or increasing all the motions in a proportionate degree. For the same 
 purpose the wheel or sheeve, which gives motion to the endless rope, may 
 also have grooves of different diameters. The sheeves that may be changed 
 for increasing or diminishing the twisting motions, are the four sheeves t r 
 for one end of the machine, and v s for the other, as seen in fig. 471 . In 
 order to obtain more or less travelling motion, the belts may be made to run 
 either on the sheeves 1 and 9, and 6 and 10, or on 2 and 8 and 5 and 11, 
 or on 3 and 7 and 4 and 12, as seen in fig. 469. 
 
 Fig. 475 (within which are .figs. 476, 477, 478, and 479) represents an 
 end view of a rope-ground building, set down as eighteen feet wide inside. 
 It is merely divided into portions, to show some different modes of diversi- 
 fying spinning-machines upon this principle, the different situations in which 
 they may work, and the proportion of room they may occupy according to 
 the number of spindles. 
 
 Figs. 478 and 479 show end views of two forms of spinning-machines, 
 different from each other, and from the one already described; but all upon 
 the same principle. The machine in fig. 478 is represented as moving on a 
 railway M M, underneath the beam L, having spindles both above and be- 
 low. The parts shown in the figure are as follows : N N two of the truck- 
 wheels. O P the endless rope sheeves. Q one of the rollers for turning the 
 spindles. R a sheeve on the end of the roller, answering the same purpose 
 as t and v in fig. 471 . W part of a sheeve on the truck-wheel axle, answer- 
 ing the same purpose as one of those on the axles o and p in figs. 469 and 
 470. The carriers, the whirls, the spindles, and their bands, in this machine 
 are the same as in the spinning-machine already described ; and their situa- 
 tions are so obvious, as not to require particular characters of reference. 
 Such part of the figure as consists of framing will be obvious. One side of 
 the railway is fixed to the post K ; the other side is fixed and rests iqiou 
 
THE OPERATIVE MECHANIC 
 
 42B 
 
 the iron fixture S, hanging from the beam L, which also serves tlie same 
 purpose for the adjoining railway. X one of the guide pullies for tlie end- 
 less rope. T a rail, (which may occasionally be removed,) laid across, and 
 answering the purpose of both railways, from post V to K, having upright 
 pins at proper distances, for the purpose of bearing and keeping separate 
 the yarns of the lower spindles. The hooks fixed to the under side of the 
 beam L are to answer the same purpose for the yarns of the upper spindles. 
 In order to lay the yarns upon these hooks, a separate guide upon each 
 spindle is fixed upright in a slender rail, fastened to, and projecting two or 
 three feet from, and parallel with, each end of the machine. The shape of 
 these guides is the same as the hooks in the beam, with this exception, that 
 each one has an eye at the point, to convey the yarns in a slanting direction 
 from the spindles, and to lay them upon their respective hooks in the beam 
 when spinning, and also to lift them off when winding up. The manner in 
 which the guides pass between the hooks may be seen in fig. 477, where a 
 represents the projecting rail; the guides, two only of which are marked ; 
 it must here be understood, that the spindles are not opposite the eyes of 
 their respective guides, but exactly opposite the upright part of them, and 
 on a level with the eyes. There are many other ways by which the hooking 
 up of the yarns may be effected, but the method just described is conceived 
 to be the most simple. The space between the post V and the iron fixture S, 
 is the room to be occupied by the other spinning-machine. 
 
 The spinning-machine, fig. 479, is represented as moving on a railway, 
 laid upon the beam L. It will be seen that this machine is nothing more 
 than the lower part of the one last described, having no spindles on the upper 
 part. The guide pins are in this method driven into the beam. The empty 
 space to the right of this machine is the room to be occupied by its fellow. 
 Tlie letters of reference used in fig. 10, and its appurtenances, apply to the 
 same parts whenever they are used in fig. 479, and its appurtenances. 
 Though these machines (the end views of which are shown in figs. 478 and 
 479) are different from each other in form and arrangement of machinery, 
 and also from the form and arrangement of the one shown in figs. 469, 470, and 
 471, yet the same principle of the travelling and twisting motions is appli- 
 cable to all, and therefore it is unnecessary to enter into further explanations 
 respecting them. 
 
 Fig. 480 shows the method of giving the after-twist. As the apparatus 
 for this purpose is to be applied to each of the endless rope shafts in each 
 machine, a description of the apparatus as belonging to one of them may 
 be sufficient. This figure is a side view of the apparatus, and is represented 
 as applied to the shafts/, in fig. 471 ; the same characters of reference there 
 used being retained in the present figure, where they denote the same parts. 
 The apparatus for the after-twist is merely an addition, which on the lower 
 part of the figure consists of a catch on the under side of the sheeve s, a cor- 
 responding catch and catch-box 25, carried round by the shaft, and the 
 lever or swinger 26 to act on the catch-box. The rod 23 is lengthened, to 
 connect this swinger with the other two. On the upper part of the figure 
 is the remainder of the apparatus, consisting of a catch on the upper side of 
 the catch-box 13 ; the worm on a loose round on the shaft 27, with a catch 
 on the under side, to operate with its corresponding catch on the catch-box 
 13 ; the screw-wheel 28 to act in the worm ; the arm 29, on a loose round 
 on the axis of the screw-wheel, confined near the circumference of the 
 wheel by the staple 30, but having play the width of the staple, the end 
 of the arm farthest from the axis being intended to act on, and press down, 
 the swinger 19; and the spring 31, fixed on the v/heel, which presses 
 against the back of the arm. 
 
 Tlie v/hole of the macliinery in the figure is represented out of the gccr, 
 
AND MACHINIST. 
 
 429 
 
 and is in the position as when ready to set off from one end of the spinning- 
 ground, to follow the yarns to the winding-machine. In that position it 
 continues until it has arrived at the winding-machine, and the yarns are 
 disengaged from the spindles when the main lever 17 is lifted up by hand 
 into the catch 24, for the purpose of putting the spinning and travelling mo- 
 tions into geer, as formerly described. By the raising up of this lever tlie 
 swinger 19 is pulled down, and the arm 29 is thus disengaged, which hav- 
 ing play within the staple, swings forward by its own weight, clear of the 
 swinger, which is hollowed or bent at that place for the purpose. The ob- 
 ject of this is, that the arm may not be in the way of the swinger 19 the 
 next time it goes into geer with the worm. When the machine has returned 
 to the other end of the ground, and the yarns consequently are spun to their 
 full length, the catch 24, on which the main lever rests, is thrown back by 
 the machine going against a fixture in the ground, as has been before 
 mentioned, and the lever (being sufficiently weighted at the handle end) 
 drops down, by which means the travelling motion is stopped. The twist- 
 ing motion would also be stopped, were it not, (as will be seen from the 
 figure) that though the catch-box 14 is throwm out of geer with the sheeve s 
 on the upper side, the catch-box 25 will be at the same instant, and by tlie 
 same movement, thrown into geer with it on the under side, so that the 
 twisting motion continues. The under side of the catch-box 13, being 
 thrown out of geer with the pinion k, (which stops the travelling motion) 
 the upper side of it will be at the same instant, and by the same movement, 
 thrown into geer with the worm 27, which consequentiy gives motion to the 
 screw-wheel 28 ; the arm 29 (which it will be recollected is then hanging 
 down) is also carried round with the wheel ; and when it comes in contact, 
 having nearly made one revolution with the swinger 19, it forces it down, 
 and by this means puts the catch-box 25, as well as its own, out of geer, and 
 causes the whole of the machinery to stop. The use of the spring 31, press- 
 ing against the back of the arm, is to cause it to force, as soon as the catches 
 13 and 25 are out of geer, the swinger 19 a little further down, wdiich it will 
 then be enabled to do, inconsequence of the resistance against it being de- 
 creased ; the object of this is to prevent any jarring of the catches when in 
 that situation. The spring is prevented forcing too far by a stop. Anotlier 
 method of forcing the swinger thus much further down may be adopted, by 
 fixing a pin or fang to project from the framing of the machine, so as the 
 end of the spring above mentioned may come in contact with it a little be- 
 fore the time when the arm begins to force down the .^winger, in order that 
 the arm may be relieved from the pressure of tlie spring until the arm has 
 forced the swinger down nearly to the point of sending the catches out of geer, 
 at which time the end of the spring, having got free of the pin, comes with 
 a sudden blow against the back of the arm, and thus sends down the catches 
 clear of those with which they were in geer ; the spring in this case also is 
 prevented from forcing too far by means of a stop. The time the screw- 
 wheel is in going round is the time allowed for the after-twist : but should 
 one wheel not allow sufficient time for the purpose the motion may be farther 
 decreased, by any usual and well-known means, and change wheels may be 
 applied to suit the different kinds of yarn. 
 
 In tempering the strands of all kinds of cordage, whether 
 shroud, hawser, or cable-laid, it is well known that from 
 various causes an inequality of tension between the different 
 strands intended for the same rope takes place, and is most 
 commonly apparent during or after the operation of hardening, 
 some of the strands becoming too slack, others too tight, and 
 
430 
 
 illE OPERATIVE MECflANfC 
 
 consequently of unequal lengths, though ovs,ginally they 
 may have been of equal length, and have received the same 
 twisting or number of turns by machinery of the most improved 
 and perfect construction. In cases, therefore, where this in- 
 equality appears, the strands require to be rectified, by being 
 brought to an equal degree of tension, in order that each 
 may bear its equal portion of strain in the rope when made. 
 The operation for effecting this object is commonly called 
 tempering the strands ; and the method in general practice is 
 to give more twist to a slack strand, or to take twist out of a 
 tight one, or to do both. In some rope-grounds where the ma- 
 chinery is driven by steam, or other considerable power, the 
 method adopted is to give more twist to the slack strands, 
 which is done by stopping the twisting of the tightest strand, 
 by throwing its hook out of geer, and to keep it waiting in 
 that position until the slack strands have twisted up to the 
 same tension. 
 
 These methods in most cases are defective ; because the 
 strand to which more twist is given is thereby rendered less 
 pliable, and is of smaller circumference ; consequently it can- 
 not top or lay up in the rope evenly and regularly with the 
 other strands which have less twist ; for the harder twisted 
 one will in the rope sink inwards, and the others stand out- 
 wards and form more of a spiral round the harder twisted one, 
 which will thereby have more than its proportionate strain 
 in the rope to bear, and will also be least enabled, when 
 under a strain, to stretch up, so as to avail itself of the as- 
 sistance of the others, and by consequence must be the first 
 to break. Should the inequality of tension be occasioned by 
 any original inequality of thickness in the strands, the smallest 
 one will, during the process of hardening, become the slack- 
 est, and in tempering by twisting it up to the tension of the 
 tightest, the inequality of size will by that means be increased ; 
 for the more it is twisted, the still smaller in circumference, 
 as well as shorter in length, will it become. But, supposing 
 all the strands were originally of equal thickness, and that the 
 inequality in tension proceeded entirely from an error in the 
 original lengths ; it is plain, that, by tempering according to 
 the methods in question, (and no other methods, after the 
 strands are fixed on the hooks, and the work has commenced, 
 can, ' y any machinery hitherto in use, conveniently be adopted,) 
 the same defective principle still applies, which, by causing 
 one strand to be harder twisted, and consequently to become 
 of a smaller size, and another to be softer twnsted, and to be- 
 come of a larger size, prevents the whole from jointly forming 
 
AND MACHINIST. 
 
 431 
 
 It regular and perfect rcpe, and to stretch equally when under 
 a stniiuj as already described. 
 
 As a more convenient, accurate, and certain method, than 
 any hitherto practised, appeared to be necessary, Mr. Dun - 
 can invented and adopted a new mode of tempering the 
 strands of all kinds of cordage, whether shroud, hawser, or 
 cable-laid : the nature and general principle of which is, to 
 cause any one strand-hook of the foreboard, or foreboard-ma- 
 chine, when the strand attached to it requires to be tightened, 
 to recede from its corresponding opposite hook of the sledge 
 or stranding machine, to which the other end of the strand is 
 attached ; or when it requires to be slackened, to cause it to 
 advance towards its corresponding opposite hook, thus bring- 
 ing all the strands to an equal tension, without one strand- 
 hook making more revolutions than another. And, what is of 
 essential importance to this invention, the operation may be 
 performed leisurely, as occasion may appear to require, either 
 before, during, or after hardening the strands, without stop- 
 ping the twisting, or other motions, or occasioning any inter- 
 ruption to them whatever; and with more ease, minute 
 accuracy, and useful effect, than by any other method yet 
 practised for the purpose. 
 
 In order more particularly to exemplify and illustrate this 
 part of the invention, we have annexed engravings of the 
 machinery which Mr. Duncan has contrived and adapted for 
 the purpose. 
 
 In fig. 481 , ABC represent the upper part of the framing in which the 
 machinery, placed at the foreboard, is fixed; C being the front of it, facing 
 or looking down the rope-walk. D is a toothed wheel, receiving motion 
 from any external machinery. This wheel drives the other toothed wheel E, 
 and either of them can be changed to suit the speed of the motion required. 
 The toothed wheel E is fixed upon the axis of, and gives motion to, the 
 toothed wheel or fluted cylinder F ; which cylinder drives the four pinions 
 J , 2, 3, 4, whose axles, to the hooks of which the rope strands are attached 
 when twisting and tempering, are the four strand hook spindles «, h, c, d. 
 To answ'er the purpose of the invention, the strand hook spindles, besides 
 having the rotative or twisting motion which we have already described, 
 are so contrived, for the tempering of the strands, that any one or more of 
 them may, while the twisting motion is or is not going on, be made to 
 slide, in a horizontal direction, parallel with the axle of the cylinder F, 
 along any part of its length, either backward or forward, as shall now be 
 explained. The strand hook spindles having to slide, as has been said, in 
 a direction parallel to the axis of the cylinder, are of course placed in that 
 direction, and so as their pinions may pass each other. The positions of 
 these pinions round the cylinder are seen in fig. 482, which represents a 
 front view of the machinery ; the same references in each figure being used 
 to denote the same part. As all the four strand hook spindles, with their 
 accompaniments and immediate connections, are precisely the same, a 
 description of one will be sufficient ; we will therefore take the spindle 
 in fig. 481. GH is a long or male screw, a few inches longer than the 
 
432 
 
 THE OPERATIVE MECHANIC 
 
 cylinder, upon which is fitted tlie nut or female screw, e, having spokes or 
 arms, to admit of it being turned by hand. Joined fast to this long screw 
 is a head-piece or claw f, within which a carrier or step is fitted, and in 
 which the adjoining end of the strand hook spindle revolves. Two collars, 
 g and hj fitted on the spindle, one on each side the step, cause the spindle 
 to accompany the long screw, either backward or forward, when moved by 
 turning the nut e, the rotative motion of the spindle going on at the same 
 time if required ; i and k are two steps or guides, fixed on the cross 
 framing B and C, through which the spindle may pass and repass, and in 
 which it also revolves ; / is a carrier of the same description, fixed on the 
 cross framing A, through which the long screw may pass and repass, but 
 without revolying. Fast upon, and projecting from the head-piece/, and 
 consequently accompanying the long screw and spindle in the sliding 
 movement, (see the side view, fig. 483,) is the tongue m, the end or point of 
 which is fitted to pass along during that movement in a slot in the rail n, 
 fixed parallel with the long screw and spindle, between the two cross 
 bearers A and B. 
 
 The object of this contrivance is to prevent the spindle 
 (one end of -which, as has been shown, revolves within the 
 head-piece of the long screw) from carrying round the screw 
 along with it, and to keep the screw and its head-piece at ail 
 times steady, and in a direct line with the spindle. For the 
 purpose of keeping the long screw stationary in the situation 
 to which it may have been last set, the pull of the strand on the 
 hook (by pressing and abutting the screw-nut e against the 
 back of the carrier /) will always be found to be sufficient. 
 The diameter of the cylinder F may be about two feet, and 
 that of each of the fore pinions 1, 2, 3, 4, about one foot, 
 more or less, according to the speed desired, and the discre- 
 tion of the mechanic. The pitch of their teeth should be the 
 same as that of the teeth of the cylinder. The length of the 
 cylinder should at least be equal to the greatest difference or 
 inequality of length ever likely to take place between the 
 slackest strand and the tightest strand intended for the same 
 rope, previous to, or during, the operation of hardening, when 
 they are both brought to an equal tension by tempering 
 according to this method. The inequality of length, or, in 
 other words, of tension, which takes place in the strands 
 during the process of hardening them, is generally found to be 
 in proportion to their circumference, and is more in a set of 
 the large strands than in the small. In rope- walks, therefore, 
 where cordage of the largest size is manufactured for the use 
 of his Majesty’s navy, the length of this cylinder should not 
 be less than four feet ; but Mr. Duncan has found, by expe- 
 rience, in manufacturing cordage for merchantmen of the 
 greatest burthen, that few cases occurred where it was requisite 
 for the length to be more than three feet. In rope-walks 
 where cordage on the common principle is manufactured, some 
 additional length is necessary. Each of the four pinions is 
 
AND MACHiNlST. 
 
 433 
 
 fastened upon the middle of the length of its strand hook 
 spindle. Supposing, therefore, that the pinion 2 should be 
 set so as to be exactly at one end of the cylinder next to the 
 cross framing B, it must be enabled to slide along to the 
 opposite end next the cross framing C, and also back again 
 to B ; for this purpose the spindle must always be kept in 
 its steps or carriers, z and /c, which support it, and in which 
 it both slides and revolves, and therefore it requires to be 
 double the length of the cylinder, besides an additional lengtli 
 equal to the spaces in its passage occupied by the necessary 
 steps, framing, clearances, &c. The length of the long screw 
 G H, and of the rail are each the length of the cylinder, 
 and correspond with, or are a few inches longer than the 
 sliding distance, to allow for steps, &c. as above. It has 
 been shown, that the cylinder drives the four strand hook 
 spindles, and that any one of them can be moved, by means 
 of its screw, either backw'ard or forward, without interrupting 
 its own rotatory motion, or the rotatory motion of any of the 
 others ; the teeth of the pinions being for this purpose kept 
 in geer with, while at the same time they are made to slide 
 along between, the teeth, or in the flutings of the cylinder. 
 
 Suppose, then, that the strands are attached to their 
 respective hooks, and the pinions set so as to be all at an 
 equal distance from each end of the cylinder, and all the 
 strand hook spindles going round, twisting and hardening 
 the strands, the operation of tempering is performed merely 
 by turning round, by hand, as often as required, any one or 
 more of the screw-nuts either way about, as the case or cases 
 may require, according as any one or more of the strands 
 require slackening or tightening for bringing them all to an 
 equal tension. Thus, in order to slacken a tight strand, its 
 hook must be advanced forward further from the front of the 
 framing C ; and in order to tighten a slack strand, its hook 
 must be drawn in, towards the framing. 
 
 Fig. 484 is a side view, representing some variatiofiin the machineiy for 
 effecting the sliding movement of the strand hook spindles on the same 
 principle, and answering the same purposes, as the ‘plan in fig. 481, already 
 described. After the full descriptions and explanations already given, a 
 very short account will be sufficient to make this fully understood : 6 is a 
 strand hook spindle, similar to those in fig. 481, excepting that the pinion 
 2 is not made fast upon it, because it has to pass or slide through the axle 
 hole of the pinion. In order, that the spindle may at the same time 
 revolve with the pinion, the slot 10 is cut upon one side of the spindle, 
 (the length of the slot being the sliding distance,) which slot receives a 
 feather or key in the axle hole of the pinion, through which the slotted part 
 of the spindle is to pass and repass, as occasion may require, the feather 
 always remaining in the slot to carry round and give the rotatory of 
 
434 
 
 THE OPERATIVE MECHANIC 
 
 tv/isting motion to the spindle. The parts /, gy and h are exactly the 
 same as tlie parts which have the same characters in fig. 481. I is a rack, (to 
 answer the same purpose as the long screw in fig. 481,) which the pinion o, 
 by means of the handle p, moves either backward or forward. The ratchet- 
 wheel, 7 , and its catch, hold the rack and pinion stationary in the situation 
 to which they may be set ; i i and k are the steps in which the spindle 
 revolves, and through which it also slides ; r r are two rings or washers, 
 loose upon the spindle, between the steps i i and the pinion 2, intended to 
 qualify the friction during both the sliding and the rotatory operation of 
 t-he spindle ; # is a guide or step for the rack to slide in, made square at 
 the bottom, which renders the tongue and slot, shown in fig. 48.3, unneces- 
 sary. The wheel K, receiving motion from any external machinery, drives 
 the pinion 2. Change wheels, for varying the motion, may be applied to 
 this method in the same way as in fig. 481. 
 
 From what has already been described, it will appear, that 
 the strand hook spindle may, by means of the rack I and 
 pinion o, be drawn or slided either backward or forward, 
 through its pinion 2, without interrupting its rotatory motion; 
 the pinion 2 always keeping in geer with the wheel K, by which 
 it is driven, and which latter may receive its motion from 
 any external machinery. Referring, therefore, to the former 
 description, it will be evident, without further explanation, 
 by what means the strands are to be tempered by this variation 
 in the machinery. 
 
 The reader will observe that there are two principles by 
 which the strands of cordage may be tempered or brought to 
 an equal tension ; the one by causing any one or more of the 
 strand hook spindles either to advance or recede, whereby an 
 equal tension will be effected without one spindle making more 
 revolutions than another ; and the other, that of causing any 
 one or more of the strand hook spindles to be at rest while 
 the others are revolving ; whereby an equal tension will be 
 effected by an unequal number of revolutions. If one of 
 these two principles only is to be adopted, Mr. Duncan 
 prefers the former, as being generally more appropriate and 
 effectual. As, however, it sometimes occurs in practice, 
 that the application of the one principle, sometimes of 
 the other, and sometimes of both, proves to be the most 
 proper and effectual remedy, Mr. Duncan has invented a 
 still more perfect method, by which either or both of the 
 principles may be practically applied in one set of machinery. 
 This object which had never, we believe, been before accom- 
 plished, is effected merely by applying to either of the two 
 varieties of machinery before described, an additional appa- 
 ratus, so that all kinds of cordage-strands may thereby be 
 tempered, either entirely, by the principle of causing any 
 one or more of the strand hook spindles to advance or 
 

 K 'IDl^ :K. M V FA € TIT MK 
 
 From J3l to tS l 
 
 n.io 
 
 Temfyerl/uf 
 
 \i7eAeX: ^tranA 
 
 
AND MACHINIST. 
 
 435 
 
 recede; or entirely, by causing any one or more of the 
 strand hook spindles to be at rest while the others are 
 revolving'; or partly by the one and partly by the other, 
 according as the original cause occasioning the inequality of 
 tension in the different strands may point out ; the whole, or 
 any part, of the operations going on, either together or 
 separately, as may be found convenient, without interruption 
 to each other. 
 
 Fig. 485 is a plan showing the additional machinery for tempering, by 
 combining the two principles as adapted for the first described machinery, 
 represented in fig. 481. The difference between the machinery of fig. 481, 
 and that of fig. 485, consists chiefly in the latter having its pinion 2 loose 
 upon the twisting spindle 5, but confined between two collars, which are 
 fast upon the spindle. The reason of the pinion running on a loose round 
 is, that it may be either put in or out of geer with the spindle, by means of 
 the catch-box t and lever u. The catch-box has a slot, fitting a feather 
 on the spindle, in order that it may revolve with it, as well as slide in or 
 out of geer, when moved by the lever. The ratchet-wheels v and w are 
 fast upon the spindle, one having teeth cut the reverse of the other, that 
 either of the two palls a: and y may, when the spindle is thrown out of geer 
 with the pinion, prevent the strands from untwisting, as otherwise the 
 spindle would be at liberty to be acted upon by the force of twist already 
 in the strand. The pall y is flat towards the point for holding against the 
 ratchet-wheel lo for a right-hand twist, and the pall x is hooked towards its 
 point for holding the wheel v for a left-hand twist. So far, this apparatus 
 would serve the purpose either of keeping in geer, or stopping the rotatory 
 motion of the spindle, provided it were not also required to perform the 
 sliding movement. In order, therefore, to complete the apparatus for both 
 these purposes, the arm z, fastened to the claw or head-piece /, and forming 
 one piece with the long screw G H, stretches alongside, parallel with the 
 spindle, so that its other end is nearly opposite to the pinion, where it is 
 furnished with two ears, having each an eye or ring, 7 and 7, fitting easy 
 upon the round iron rod 8 ; \vhich rod is fixed parallel with the spindle, 
 between the cross framing B and C. The step 9, on the cross framing B, 
 serves as a guide for the arm z. It is necessary that the distance between 
 B and C should be as much longer, than the distance in, fig. 481, as the 
 length taken up or occupied by the catch-box and ratchet-wheels. The 
 spindle also will require this additional length. The arm z, during the 
 sliding movement, has to conduct with it, along the rod 8, the lever w, and 
 the two ratchet palls x and y, the rod serving them also as a guide during 
 the sliding movement, and at all times as an axle. Though the pinion 2 
 is always in geer with, and carried round by, the cylinder F, fig. 481, yet 
 the spindle only goes round when put in geer with the catch-box by the 
 lever ; therefore the rotatory motion of the spindle may at any time, and 
 for any space of time, be stopped, for the purpose of causing the twist o 
 its strand' to cease, while at the same time the other strands are twisting 
 up. Though only one spindle is here spoken of, it is evident that all or any 
 of them may, from being furnished with the apparatus now described, be 
 made either to give, or cease from giving twist, while any one or more of 
 the spindles either may or may not, as required, be performing the sliding 
 movement. 
 
 Fig. 486 is a side view, showing the method adapted for the second 
 described machinery, as represented in fig. 484, the apparatus in thij case 
 
 2f2 
 
436 
 
 THE OPERATIVE MECHANIC 
 
 applying to the narrow wheel, and that in the former case of fig. 485, apply^^ 
 ing to the wide wheel or cylinder F. The difierence between the one and 
 the other is, that the spindle and pinion in fig. 485, slide together, as in 
 fig. 481, whereas in the figure now to be described the spindle slide? 
 through the pinion, as in fig. 484. The spindle b in this figure is similar to 
 that in fig. 484, having a slot, to receive a feather, which is fixed in the 
 catch-box t. The pinion 2, which is always in geer wdth the wheel K, is 
 fastened on the bush 11. running loose upon the spindle b. This bush, 
 being furnished with the collar 12, serves, by means of its revolving in the 
 cavity 13, adjoining the step i, to keep the pinion in its proper place, 
 during the spindle’s sliding movement : i and k are two steps, answering 
 the same purpose as those of the same characters of reference in fig. 484 ; 
 V and IV are two ratchet-wheels, fast to each other, but not fast on the 
 spindle, having a feather, fitting the slot of the spindle, in order that they 
 may hold it fast when occasion requires, and that it may pass and repas.s 
 through them during the sliding movement. These ratchet-wheels are 
 furnished with their two palls a: and ;?/, altogether answering the same pur- 
 pose as those described in the former fig. 485. The catch-box t, having 
 also a feather, fitting the slot, is furnished with a lever, (not shown in the 
 figure,) answering the same purpose as the one marked u, in fig, 485 ; but 
 to suit the present case, it works on a stationary pivot, fixed to the framing 
 of the machine. The two ratchet palls also work on pins fixed to the 
 framing; and their wheels v and w, being furnished with the rim or 
 fencing 14, are kept always opposite to the palls, by means of a bracket, 
 (fixed to the framing, but not seen in the figure,) hollowed out to receive 
 the rim. It will be evident, from what has here been said, that the opera- 
 tion of striking in and out of geer the rotatory motion of the spindle is- 
 performed exactly in the same manner, and also answers the same purpose, 
 as that described under fig. 485 ; and that the sliding movement of the 
 spindle in both cases is performed in the same manner, and answers the 
 same purpose, as described under fig's. 481 and 484, either one or other of 
 the methods, under figs. 485 and 486j combining the two principles of tem- 
 pering strands in the manner previously pointed out. 
 
 Though in the first- described machinery it has been shown, 
 that the sliding movement of the strand hooks may be 
 effected by means of a male and female screw, and in the 
 second-described machinery by that of a rack and pinion, 
 yet it will be seen, that either means may with equal pro- 
 priety be applied to either machinery. And a competent 
 mechanic, from what has been described, will easily perceive 
 that any other power, such as that of a lever, weight, or rope 
 and pulley, or one or more of them combined, may be applied 
 for the same purpose, though in the first preference be given 
 to the screw, and in the next to the rack. 
 
 The next part of the invention to be described is a 
 new method of regulating both the backward and forward 
 travelling movements of any sledge or other locomotive ma- 
 chine that is or may be used in a rope-walk. The back- 
 ward movement of the stranding- sledge, or the retrograde 
 movement of that machine towards the bottom of the rope- 
 walk by which strands are drawn out, in rope-walks whers 
 
AND MACHINIST. 
 
 437 
 
 the improved or patent principle of rope-making is adopted, 
 has hitherto been effected by means of a rope applied in 
 different ways for the purpose. In some cases the rope is 
 made to haul the sledge backwards, by fastening one end of 
 it to the sledge, and the other round the capstan or barrel, 
 at the bottom of the rope- walk; and in other cases the rope 
 is stretched tight along, and made fast at each end of the 
 rope- walk, and two or more doubles or bights of it passing 
 round and grasping the same number of grooved binding 
 sheeves in the sledge, which revolve by connection with the 
 rotative motion of the strand hooks, from which the other 
 motions are derived : thus the sledge works itself backwards 
 along the rope. 
 
 The great object to be attained in regulating this backv/ard 
 motion is, to cause it always to preserve a certain speed in a 
 given ratio with that of the rotative motion, in order that the 
 strands may always receive the degree and uniform distribution 
 of twist intended; But in whatever way a rope has hitherto 
 been applied for that purpose, the object has never been 
 effectually attained, nor the operation conveniently performed, 
 because, from the elasticity and specific gravity of the rope 
 itself, extended along the whole length of the rope-walk, it 
 has been found impossible to keep it accurately stretched, 
 and equally tight from one end to the other, so that when 
 the sledge is in motion, particularly when first struck into 
 geer, it pulls up the slack of the rope froi# the bottom of the 
 rope-walk, and its retrograde motion is thus retarded in 
 proportion as the rope may stretch, slip, oi* give way. 
 
 The retrograde motion loses therefore its relative speed 
 commensurate with that of the rotative motion of the strand 
 hooks, which have in the mean time, without interruption, 
 continued to put twist into the strands. Instances are not 
 unfrequent where they have been twisted to such a degree 
 as nearly to break them asunder before the rope could be 
 tightened sufficiently to cause the sledge to move on at its 
 proper speed ; and, on the whole, it is obvious, that by the 
 present method of drawing out the strands, they can neither 
 receive their proportionate twist nor the distribution of it. 
 The labour required in applying the rope is besides extremely 
 inconvenient and troublesome, because it requires to be first 
 fixed to the sledge, or round its binding sheeves, at the top 
 of the rope-walk, then tightened, and afterward disengaged 
 at the bottom, on every single occasion of drawing out a 
 strand or set of strands. The plan also is expensive, because 
 the constant wear and tear is considerable, and requires th?c 
 
438 
 
 THE OPERATIVE MECHANIC 
 
 rope to be frequently renewed, An iron chain may indeed 
 be applied for the purpose, and though not requiring to be so 
 frequently renewed, it is equally objectionable with the rope 
 in most other respects, and on some accounts more so. The 
 forward movement of the stranding, topping, and dragging 
 sledges, is that slow progressive movement necessarily re- 
 quired towards the top of the rope-walk by the shortening or 
 shrinking up of the strands in twisting, while forming on the 
 common principle, and of the strands and cordage, either 
 common or patent, whilst hardening and topping. It will 
 readily be seen, that this movement should also be uniformly 
 regular, in a given proportion to the twisting motion, and 
 that the travelling distance should be neither more nor less 
 than the length the strand or rope ought to shrink up. 
 According to the usual method, a number of press barrels or 
 weights are placed on the stranding or topping sledge, or on 
 a drag sledge, attached to their tail end, to serve as a resist- 
 ance against the pull of the strand or rope when shrinking 
 up. But as the quantity of weight to be applied is to be 
 varied and proportioned to the size of the strand or rope, and 
 degree of twist required, and as the friction of the drag on 
 the ground is greater on some parts than on others, the 
 operation, depending on criterions so uncertain, must be 
 attended with a great degree of irregularity, both with regard 
 to the sledge sliding faster or slower, and also with regard to 
 the whole length to which, eventually, it may be dragged ; 
 thereby occasioning a proportionate irregularity, both in the 
 distribution and total quantity of twist or lay in the strands 
 or rope, corresponding with their length. 
 
 The object, therefore, of this invention, with regard to the 
 backward movement, is, to cause the sledge, or any other 
 locomotive or travelling machine used, or that may be used, 
 in a rope-walk, to travel and recede down the walk at one 
 uniform speed, such as shall be predetermined as proportion- 
 ate with the rotatory speed of the twisting hooks of tlie 
 machine, so as to cause the twist to be uniformly regular 
 throughout each operation. And the object of this invention, 
 with regard to the forward movement, is, to cause the sledge, 
 or other movable machine, to which any kind of strand or 
 rope may be attached, for the purpose of being formed, 
 hardened, or laid, to travel slowly, and advance up the walk, 
 during the operation, at one uniform predetermined motion, 
 and precisely the length or distance assigned to it, equal to 
 that which the strands or rope ought to shrink up in the 
 operation. 
 
AND MACHINIST. 439 
 
 • 
 
 Having stated the object of this part of the invention, 
 we shall now proceed to show that the nature and funda- 
 mental principle of it, and the means for accurately and 
 conveniently attaining all the objects in view, both with 
 regard to the backward and forward movement, consist in a 
 rack, or rack-way, of cast-iron, or other suitable material, 
 laid down and fixed upon and along the rope-walk, from one 
 .end of it to the other, parallel with a railway, upon which 
 the stranding sledge, or any other sledge or locomotive 
 machine, is to travel. The teeth of the rack- way are of the 
 same pitch as the teeth of a wheel whose axle is m the 
 machine. The motion of this wdieel being given and 
 governed by the other motions in the rxiachine which turn 
 the twisting hooks, the travelling speed of the machine, 
 whether working backward or forward, becomes at all times 
 uniform, and in a given certain ratio, with the speed of its 
 twisting motion ; for the whole machinery being composed of 
 geer and toothed work, no part of it is liable to slip or yield. 
 The required speeds, both of travelling and twisting motions, 
 are adjustable by change wheels, to suit each other in that 
 machine, as well as in any other machine or machines that 
 may be employed in one and the same operation. The whole 
 machinery may be driven by an endless rope, receiving its 
 motion from external machinery at the top of the rope-walk, 
 or by any other means in use for driving locomotive ma- 
 chinery ; for, we need scarcely observe, that it is not 
 necessary, for the purpose of producing accurate work, that 
 the motion which governs all the others should be uniform, 
 because, whether the original motion be quicker or slower 
 at one time than another during the operation, the motions 
 dependant on it will still keep their proportionate speed. 
 The only difference will be in the time in which the work 
 may be finished. We have mentioned the particular cases 
 in which this part of the invention is more essentially useful ; 
 but Mr. Duncan claims the application of the rack, in 
 manner described, as an invention subservient to every 
 purpose, in any stage or process of rope-making, for which 
 regularity of travelling motion to any machine, either 
 backward or forward, in a rope-walk or elsewhere, may be 
 required 
 
 In that part of th« drawing’ entitled, “ Backward and Forward Move- 
 ment,'’ fig, 487 represents the side view of a travelling sledge, or locomotive 
 machine, of the description, and for the purposes referred to, moving on 
 the railway M M. A B is a side view of the rack-way laid down and 
 fixed on the wood sleeper N N, or other suitable material, supposed as 
 extending from the top to the bottom of tlie rope-grouiid. This machine 
 
440 
 
 THE OPERATIVE MECHANIC 
 
 is represented as driven by the endless rope O ; 13 and 14 are two guide 
 pullies, to conduct the rope in going on and coming off the large sheeve or 
 grooved wheel P, round which that rope (driven by external machinery, 
 and running from top to bottom of the rope-ground) passes, by which the 
 first movement in the sledge is given. This sheeve, giving motion to the 
 spindle or shaft Q, and being coupled with the shaft R, turns the pinion 1, 
 which drives the pinion -2, upon whose shaft, S, is the small bevel-wheel 3, 
 driving the large bevel-wheel 4, upon whose shaft again is the spur-wheel 5, 
 driving the other wheel 6 ; w'hich last wheel works in the rack-way. This 
 wheel is not fast upon its shaft, being capable of sliding thereon, for the 
 purpose of being put in and out of geer with, the rack by means of the 
 lever T- The machine travels on the lailway on four tru ck-w heels : the 
 two shown in this figure are marked 7. The pinions 1 and 2 are change- 
 able, to suit the different travelling speeds required. 
 
 So far as has been now described refers only to the backward movement 
 of the machine ; which movement, it must be understood, is in the direc- 
 tion along the rack-^way, as from A towards B. The contrary, or forward j 
 movement is of .course in the direction from B towards A, and is effected by 
 giving a reverse turn to the wheel 6, which works in the rack-way. The ne- 
 cessary machinerv for this purpose is the small pinion 8, on the shaft Q, 
 driving the wheef 9, on the shaft U ; which last shaft, and the one coupled 
 ■with it, W, lie parallel with, and extend to, the end of the shaft R, in order 
 that the pinion 10, fixed on the end of W, may, when required, work in the 
 pinion 2. The shaft S then becomes common to both the pinions 1 and 10, 
 and may, as required, be driven by either the one or the other, the pinion 1 
 being for the backward movement, and the pinion 10 for the forward move- 
 ment, one of them therefore must be out of geer while the other is in geer. 
 The figure sho-w^s the pinion 10 as out of geer. But supposing it to be in 
 geer with 2, and the pinion 1 out of geer with it, the effect is, that a con- 
 trary motion is given to the wheel 6, which works in the rack-way, by means 
 of the intervening wheels 3, 4, and 5, before described. The twisting mo- 
 tions of this machine are produced by the shaft Q being continued to the 
 front of the machine, where the wheel 11, on the end of the shaft, drives 
 the counter-wheel 12, from whence the required degree of speed is given to 
 the twisting hooks. From what has been before described, it will be seen, 
 that the backward and forward motions of the machine are produced by 
 means of the wheel 6 working in the rack-way either way about as required. 
 As, therefore, any predetermined quantity of twist may be given by means of 
 the change wheels 11 and 12, whilst at the same time the machine may be 
 made to travel at any given predetermined speed, either backward or forward, 
 by means of the change wheels 1, 2, and 10; and as the twisting as well as 
 the travelling motions are driven by one and the same impulse, originating 
 in the machine at the grooved wheel P ; they must always preserve a rela- 
 tive speed to each other in such proportion as may be assigned to them. A 
 forked lever, clasping on the catch-box 15, serves either to put in or out of 
 geer all the motions of the machine, excepting that of the grooved wheel P. 
 
 Fig. 488 is a view of the back end of the same machine, showing as much 
 of the machinery as is necessary for understanding it. The same characters 
 of reference used in fig. 1 denote the same parts in this. 
 
 Fig. 3 is a plan of part of the rack-way. A is the rack, and N N is the 
 wood sleeper upon which it is fastened. The forward motion of the sledge 
 is a remarkably slow movement ; the speed of the wheel 6 therefore requires 
 to be considerably reduced. The wheels shown in the figures will not re- 
 duce the motion sufficiently slow to suit every possible occasion ; but enough 
 is shown to enable a njechanic readily to produce any degree of motion that 
 maybe required. 
 
E.O MA^UFA F T FliF 
 From 485 to 488 
 
 n.7i 
 
 :bac]kwab.Ij) ^^foirwaio]) 
 
 r>>U «. 3S I StmU 
 
AND MACHINIST. 
 
 441 
 
 All or any part of the machinery which we have described 
 may be driven by the power of steam, water, wind, or animals. 
 
 In the course of describing the different machines, and their 
 component parts, adapted for the various purposes of the in- 
 vention, we have seldom taken notice either of their dimen- 
 sions or of the materials of which they may be made, because 
 no fixed rules can be given : but any competent mechanic, 
 from what »ve have shown, will be enabled to apply such 
 sizes, and use such materials, as may be suited and proportioned 
 to the nature and design of each machine, and to the power 
 which is to drive it, particularly when we add, that the figures 
 in the plates marked Tempering, and Backward and 
 Forward Movements,” are made out on a scale J of an inch 
 to a foot, and that the dimensions there given are such as 
 inay with effect be applied in practice. 
 
 SAW-MILLS. 
 
 Saw-mills, constructed for the purpose of sawing either 
 timber or stone, are moved by animals, by water, by wind, or 
 by steam. They may be distinguished into two kinds ; those in 
 which the motion of the saw is reciprocating, and those in 
 which the saws have a rotatory motion. In either case the 
 researches of theorists have not yet turned to any account : 
 instead therefore of giving any uncertain theory here, we shall 
 proceed to the descriptive part, and refer those who wish to 
 see some curious investigations on this subject to a Memoir 
 on the Action of Saws, by Euler, en Mem. Acad. Roy. Berlin, 
 1756. 
 
 Reciprocating saw- mills, for cutting timber, and moved by 
 water, do not exhibit much variety in their construction. The 
 saw-mill represented in fig. 450 is taken from Gray’s Ex- 
 perienced Mill- Wright ; but it only differs in a few trifling 
 particulars, from some which are described in Belidor's Archi- 
 tecture Hydrauli^e^ and in Gallon’s Collection of Machines 
 approved by the French Academy. 
 
 The plate just referred to shows the elevation of the mill. A A the shaft 
 or axle upon which is fixed the wheel B B, (of 1 7f or 1 8 feet diameter,) con- 
 taining 40 buckets to receive the water which impels it round C C, a wheel 
 upon the same shaft containing 96 teeth, to drive the pinion No. 2, having 
 22 teeth, which is fastened upon an iron axle or spindle, having a coupling- 
 box on each end that turns the cranks, as D D, round; one end of the pole 
 E is put on the crank, and its other end moves on a joint or iron bolt at F, 
 in the lower end of the frame G G. The crank D D, being turned round in 
 the pole E, moves the frames G G up and down, and those having saws in 
 ^hem, by this motion cut the wood. The pinion No. 2 may work two. 
 
442 
 
 THE OPERATIVE MECHANIC 
 
 tliree, or more cranks, and thus move as many frames of saws. No. 3 an iron 
 wheel having angular teeth, which one end of the iron K takes hold of, while 
 its other end rolls on a bolt in the lever H II. One end of this lever moves on 
 a bolt at I, the other end may lay in a notch in the frame G G so as to be 
 pulled up and down by it. Thus the catch K pulls the wheel round, while 
 the catch I falls into the teeth and prevents it from going backwards. 
 
 Upon the axle of No. 3 is also fixed the pinion No. 4 taking into the 
 teeth in the under edge of the iron bar, that is fastened upon the frame TT, 
 on which the wood to be cut is laid : by this means the frame T T is moved 
 on its rollers S S, along the fixed frame U U ; and of course the wood fastened 
 upon it is brought forward to the saws as they are moved up and down by 
 reason of the turning of the crank D D. V V the machine and handle to 
 raise the sluice, when the water is to be let upon the wheel B B, to give it 
 motion. By pulling the rope at the longer arm of the lever M, the pinion 
 No. 2 is put into the hold or gripe of the wheel C C, which drives it ; and 
 by pulling the rope 11, this pinion is cleared from the wheel. No. 5, a pinion 
 containing 24 teeth, driven by the wheel C C, and having upon its axle a 
 sheave, on which is the rope P P, passing to the sheave No. 6, to turn it 
 round; and upon its axle is fixed the pinion No.7, acting on the teeth in an iron 
 bar upon the frame TT, to roll that frame backwards when empty. By pull- 
 ing the rope at the longer arm of the lever N, the pinion No. 5 is put into 
 the hold of the wheel C C ; and by pulling the rope O, it is taken off the hold. 
 No. 8, a wheel fixed upon the axle No. 9, having upon its periphery angular 
 teeth, into which the catch No. 10 takes, and being moved by the lever attached 
 to the upper part of the frame G, it pushes the wheel No. 8 round; and 
 the catch. No. 11, falls into the teeth of the wheel, to prevent it from going 
 backward, while the rope rolls in its axle, and drags the logs or pieces of 
 wood in at the door Y, to be laid upon the movable frames T T, and car- 
 ried forward to the saws to be cut. The catches Nos. 10 and 11 are easily 
 thrown out of play when they are not wanted. The gudgeons in the shafts, 
 rounds of the cranks, spindles, and pivots, should all turn round in cods or 
 bushes of brass. Z, a door in one end of the mill-house at which the wood 
 is conveyed out when cut. W W, walls of the mill-house. Q Q, the 
 couples or framing of the roof. XXX, &c. windows to admit light to the 
 house. 
 
 Saw-mills for cutting blocks of stone are generally, though not always, 
 moved horizontally; the horizontal alternate motion may be commu- 
 nicated to one or more saws, by means of a rotatory motion, either by 
 the use of cranks, &c. or in some such way as the following. Let the hori- 
 zontal wheel A B D C, fig. 451, drive the pinion O N, this latter carrying a 
 vertical pin P, at the distance of about one-third of the diameter from the 
 centre. This pinion and pin are represented separately in No. 2 of fig. 451. 
 Lei the frame WST V, carrying four saws, marked 1, 2, 3, 4, have wheels, 
 V, T, W, W, each running in a groove or, reel, whose direction is parallel to 
 the proposed direction of the saws : and let a transverse groove P R, whose 
 length is double the distance of the pin P from the centre of the pinion, be 
 cut in the saw-frame to receive that pin. Then, as the great wheel revolves, 
 it drives the pinion, and carries round the pin P ; and this pin being com- 
 pelled to slide in the straight groove PR, while by the rotation of the pinion 
 on which it is fixed its distance from the great wheel is constantly varying, 
 it causes the whole saw frame to approach and recede from the great wheel 
 alternately, while the grooves in which the wheels run confine the frame, 
 so as to move in the direction T V v. Other blocks may be sawn at the 
 same time by the motion of the great wheel, if other pinions and frames 
 running off in the directions of the respective radii, E B, E A, E C, be 
 
■I 
 
 i: 
 
 
ANT> machinist; 
 
 443 
 
 worked by the teeth at the quadrantal points B A and C. And the contrary 
 efforts of these four frames and pinions, will tend to soften down the jolts, 
 and equalize the whole motion. 
 
 The same contrivance, of a pin fixed at a suitable distance from the centre 
 of a wheel, and sliding in a groove, may serve to convert a reciprocating into 
 a rotatory motion ; but it will not be preferable to the common conversion 
 by means of a crank. 
 
 When saws are used to cut blocks of stone into pieces having cylindrical 
 surfaces, a small addition is made to the apparatus. See figs. 452 and 
 453. Tlie saw, instead of being allowed to fall in a vertical groove, as it 
 cuts the block, is attached to a lever or beam F G, sufficiently strong ; this 
 lever has several holes pierced through it, and so has the vertical piece E D, 
 which is likewise movable towards either side of the frame in grooves in the 
 top and bottom pieces A L, D M. Tims the length K G of the radius can 
 be varied at pleasure, to suit the curvature N O ; and as the saw is moved 
 backwards and forwards by proper machinery, in the direction C B, B C, it 
 works lower and lower into the block, while, being confined by the beam 
 F G, it cuts the cylindrical portion from the block P, as required. 
 
 When a complete cylindrical pillar is to be cut out of one 
 block of stone, the first thing will be to ascertain in the block 
 the position of the axis of the cylinder ; then lay the block so 
 that such axis shall be parallel to the horizon, and let a cylin- 
 drical hole of from one to three inches diameter be bored en- 
 tirely through it. Let an iron-bar, whose diameter is rather 
 less than that of the tube, be put through it, having just 
 room to slide fr eely to and fro as occasion may require. Each 
 end of this bar should terminate in a screw, on which a nut 
 and frame may be fastened 5 the nut-frame should carry three 
 flat pieces of wood or iron, each having a slit running along 
 its middle nearly from one end to the other, and a screw and 
 handle must be adapted to each slit: by these means the 
 frame work at each end of the bars may readily be so adjusted 
 as to form isosceles or equilateral triangles ; the iron-bar will 
 connect two corresponding angles of these triangles ; the saw 
 to be used, two other corresponding angles ; and another box 
 of iron or of wood, the two remaining angles ; to give sufficient 
 strength to the whole frame. This construction, it is obvious, 
 will enable the workman to place the saw at any proposed 
 distance from the hole drilled through the middle of the 
 block ; and then, by giving the alternating motion to the saw- 
 frame, the cylinder may at length be cut from the block as 
 required. This method was first described in the Collection of 
 Machines approved by the Paris Academy. 
 
 If it were proposed to saw a conic frustrum from such 
 a block, then let two frames of wood or iron be fixed to 
 those parallel ends of the block which are intended to coin- 
 cide with the bases of the frustrum, circular grooves being 
 previously cut in these frames to correspond with the circum- 
 
444 THE OPERATIVE MECHANIC 
 
 ferences of the two ends of the proposed frustrum ; the saw 
 being worked in these grooves, will manifestly cut the conic 
 surface from the block. This, we believe, is the contrivance 
 of Sir George Wright. 
 
 The best method of drilling the hole through the middle of 
 the proposed cylinder seems to be this : on a carriage run- 
 ning upon four low wheels let two vertical pieces (each having 
 a hole just large enough to admit the borer to play freely) be 
 fixed, two or three feet asunder, and so contrived that the pieces 
 and holes to receive the borer may, by screws, &c. be raised 
 or lowered at pleasure, while the borer is prevented from sliding 
 backwards and forwards by pieces upon its bar, which are larger 
 than the holes in the vertical pieces, and which, as the borer 
 revolves, press against these pieces : let a part of the boring bar 
 between the two vertical pieces be square, and a grooved wheel 
 with a square hole of a suitable size be placed upon this part 
 of the bar ; then the rotatory motion may be given to this bar 
 by an endless-band, which shall pass over this grooved wheel 
 and a wheel of much larger diameter in the same plane, the 
 latter wheel being turned by a winch-handle in the usual way. 
 As the boring proceeds, the carriage with the borer may be 
 brought nearer and nearer the block, by levers and weights. 
 
 Circular saws, acting not by a reciprocating, but by a 
 rotatory motion, have been long known in Holland, where 
 they are used for cutting wood used for veneering. They were 
 introduced into this country, we believe, by General Bentham, 
 and are now used in the dock-yard at Portsmouth, and in a few 
 other places ; but they are not as yet so generally adopted 
 as might be wished, considering how well they are calculated 
 to abridge labour, and to accomplish, with expedition and ac- 
 curacy, what is very tedious and irksome to perform in the 
 usual way. Circular saws may be made to turn either in hori- 
 zontal, vertical, or inclined planes ; and the timber to be cut 
 may be laid upon the plane in any direction ; so that it may 
 be sawed by lines making any angles whatever, or at any 
 proposed distance from each other. When the saw is fixed at 
 a certain angle and at a certain distance from the edge of the 
 frame, all the pieces will be cut of the same size, without 
 marking upon them by a chalked line, merely by causing them 
 to be moved along, and keeping one side in contact with the 
 side of the frame 5 for then as they are brought one by one 
 to touch the saw revolving on its axle, and are pressed upon 
 it, they are soon cut through. 
 
 Mr. Smart, of the Ordnance Wharf, Westminster Bridge, 
 has several circular saws, all worked by a horse, in a moderate 
 
AND MACHINIST. 
 
 445 
 
 sized walk ; one of these intended for cutting and boring 
 tenons, used in this gentleman’s hollow masts, is represented 
 in fig. 454. 
 
 N O P Q R is a hollow frame, under which is part of the wheel-work 
 of the horse-mill., A B C D E F are pullies, over which pass straps or 
 bands, the parts of which out of sight run upon the rim of a large vertical 
 wheel ; by means of this simple apparatus the saws S S are made to revolve 
 upon their axles, with an equal velocity, the same band passing round the 
 pullies D C, upon those axles ; and the rotatory motion is given to the borer 
 G by the band passing over the pulley A. The board I is inclined to the 
 horizon in an angle of about 30 degrees ; the plane of the saw S is parallel 
 to that of the board I, and about a quarter of an inch distant from it, while 
 the plane of the sawS^ is vertical, and its lowest point at the same distance 
 from the board I. Each piece of wood K, out of which the tenon is to be 
 cut, is about four inches long, and an inch and a quarter broad, and | of an 
 inch thick. One end of such piece is laid so as to slide along the ledge at 
 the lower part of the board I, and as it is pushed on, by means of the handle 
 H, it is first cut by the saw S, and immediately after by the saw S*; after 
 this the other end is put lowest, and the piece is again cut by both saws : 
 then the tenon is applied to the borer G, and as soon as a hole is pierced 
 through it, it is dropped into the box beneath. 
 
 By the above process, at least 30 tenons may be completed 
 in a minute, with greater accuracy than a man could make one 
 in a quarter of an hour with the common hand saw and 
 gimlet. Similar contrivances may, by slight alterations, be 
 fitted for many other purposes, particularly all such as may re- 
 quire the speedy sawing of a great number of pieces into 
 exactly the same size and shape. A very great advantage at- 
 tending this sort of machinery is, that wdien once the position 
 of the saws and frame is adjusted, a common labourer may 
 perform the business just as well as the best workman. 
 
 — rtn^ir- 
 
 BARK-MILL. 
 
 The bark-mill is constructed for the purpose of grinding 
 and preparing bark till it is fit for the tanner. 
 
 Bark-mills, like most other mills, are worked either by 
 means of horses, by water, or by wind. 
 
 One of the best mills we have seen described for these 
 purposes is that invented by Mr. Bagnall, of Worsley, in 
 Lancashire. This machine will serve not only to chop bark, to 
 grind, to riddle, and pound it ; but to beam or work green hides 
 and skins out of the mastering or drench, and make them ready 
 for the ouse or bark-liquor ; to beam sheep-skins, and other 
 skins, for the skinner’s use ; and to scour and take off the 
 bloom from tanned leather, when in the currying state. 
 
446 
 
 THE OPERATIVE MECHANIC 
 
 Fig. 455 is a horizontal plan of tlie mill ; fig. 456 a longitudinal section 
 of it ; fig. 457 a transverse section of it. 
 
 A, the water-wheel, by which the whole machinery is worked. 
 
 B, the shafts. 
 
 C, the pit-wheel, which is fixed on the water-w'heel shaft B, and turns 
 the upright shaft E, by the wheel F, and works the cutters and hammer 
 by tapets. 
 
 D, the spur and bevel wheels at the top of upright shafts. 
 
 E, the upright shaft. 
 
 F, the crown-wheel, which works in the pit-wheel C. 
 
 G, the spur-nut to turn the stones I. 
 
 P, the beam, with knives or cutters fixed at the end to chop or cut the 
 Dark, which bark is to be put upon the cutters or grating i, on which the 
 beam is to fall. 
 
 Q, the tryal that receives the bark from the cutters i, and conveys it into 
 the hopper II, by which it descends through the shoe J to the stones I, 
 where it is ground. 
 
 K, the spout, which receives the bark from the stones, and conveys it into 
 the tryal L; which tryal is wired, to shift or dress the bark as it descends 
 from the stones I. 
 
 M, the trough, to receive the bark that passes through the tryal L. 
 
 ]l, the hammer, to crush or bruise the bark that falls into the dish S, 
 which said dish is on the incline, so that the hammer keeps forcing it out of 
 the lower side of the said dish, when bruised. 
 
 A, a trough, to receive the dust and moss that passes through the tryal Q. 
 
 T, the bevel-wheel that works in the wheel D, which works the beam- 
 knife by a crank V, at the end of the shaft m. 
 
 W, the penetrating-rod, which leads from the crank V to the start x, 
 the start, which has several holes in it to lengthen or shorten the stroke 
 of the beam-knife. 
 
 y, the shaft, to which the slide-rods h h are fixed by the starts n n. 
 
 hy the slide rod, on which the knife / is fixed, which knife is to work the 
 hides, &c. On the knife are tw'o springs a a, to let it have a little play as 
 it makes its strokes backwards and forwards, so that it may not scratch or 
 damage the hides, &c. 
 
 Zy is a catch in the slide rod A, which catches on the arch-head e ; and 
 the said arch-head conveys the knife back without touching the hide, and 
 then falls back to receive the catch again. 
 
 I, the roller to take up the slide-rod A, while the hides are shifting on the 
 beam b, by pulling at the handle m. 
 
 by the beam to work the hides, &c. on. Each beam has four wheels, py, 
 working in a trough-road, g g, and removed by the levers c c. When the 
 knife has worked the hides, &c. sufficiently in one part, the beam is then 
 shifted by the lever c as far as is wanted. 
 
 dy a press, at the upper end of the beam, to hold the hide fast on the 
 beam while working, 
 
 e, an arch-head, on which the slide-rod A catches. 
 
 fy the knife fixed on the slide-rod A, to work the hides, &c. 
 
 i, cutters or grating to receive the bark for chopping. 
 
 The beam P, with knives or cutters, may either be worked by tapets, as 
 described, or by the bevel-wheel T with a crank, as V, to cut the same as 
 shears. 
 
 The knife / is fixed at the bottom of the start, which is fixed on the slide- 
 rod A ; the bottom of the start is split open to admit the knife, the width of 
 one foot ; the knife should have a gudgeon at each end, to fix in the open 
 
SAW BAKbxMFLJLS 
 
 Fi.65 
 
 1 
 
 431 
 
 From 151 to 137 
 
 465 
 
 if tcfStTMA 
 
 ZEE 
 
AND MACHINIST. 
 
 447 
 
 part of the start ; and the two springs a a prevent the knife from giving too 
 much way when working. Tire knife should be one foot long, and four or 
 five inches broad. 
 
 , The arch-head e will shift nearer to or further from the beam hy and will 
 be fixed so as to carry the, knife back as far as is wanted, or it may be taken 
 away till wanted. 
 
 The roller I is taken up by pulling at the handle m, which takes up the 
 slide-rod so high as to give head room under the beam-knife ; the handle 
 may be hung upon a hook for that purpose. The slide-rod will keep run- 
 ning upon the roller all the time the hide is shifting ; and when the hide is 
 fixed, the knife is put on the beam again by letting it down by the handle m. 
 There may be two or more knives at work on one beam at the same time, 
 by having different slide-rods; there should be two beams, so that the 
 workman could be shifting one hide, &c. while the other was working. Tire 
 beam must be flat, and a little on the incline ; as to the breadth, it does not 
 matter ; the broader it is, the less shifting of the hides will be wanted, as 
 the lever c will shift them as far as the width of the hide, if required. 
 Mr. Bagnall has formed a kind of press d, to let down, by a lever, to hold 
 the hide fast on each side of the knife, if required, so that it will suffer the 
 knife to make its back stroke without pulling the hide up as it comes back. 
 Tlie slide-rod may be weighted, to cause the knife to lay stress on the hide, 
 &c. according to the kind and condition of the goods to be worked. 
 
 Hides and skins for the skinner’s use are worked in the 
 same way as for the tanner’s. 
 
 Scouring of tanned leather for the currier’s use can be done 
 on the beam, the same as working green hides ; it is only 
 taking the knife away, and fixing a stone in the same manner 
 as the knife by the said joint, and to have a brush fixed to go 
 either before or after the stone. The leather will be much 
 sooner and better secured this way than by hand. 
 
 The whole machinery may be worked by water, wind, 
 steam, or any other power ; and that part of the machinery 
 which relates to the beaming part of the hides, may be fixed 
 to any horse bark-mill, or may be worked by a horse or other 
 power separately. 
 
 OIL-MILLS. 
 
 As these kingdoms do not produce the olive, it would be 
 needless to describe the mills which are employed in the 
 southern parts of Europe ; we shall therefore content our- 
 selves with a description of a Dutch oil-mill, employed 
 for grinding and pressing linseed, rapeseed, and other 
 oleaginous grains ; and, to accommodate our description 
 still more to our local circumstances, shall employ water as 
 the first mover; thus avoiding the enormous expense and 
 complication of a windmill. 
 
 Description of fig. 458. 
 
 1 is the elevation of a wheel, over or under shot, as the situation may 
 lequire. 
 
448 
 
 THK OPERATIVE MECHANIC 
 
 i. the bell-metal socket, supported by masonry, for receiving the outcl' 
 giiageon of the w ater-wheel. 
 
 3, the watercourse. 
 
 Fig. 459. 
 
 1, a spur-whee'l upon the same axis, having 52 teeth. 
 
 2, the trundle that is driven by No. 1, and has 78 staves. 
 
 3, the wallower, or axis for raising the pestles. It is furnished round its 
 circumference with wipers for lifting the pestles, so that each .nay fall twice 
 during one turn of the water-wheel : that is, three wipers for each pestle. 
 
 4, a frame of timber, carrying a concave half cylinder of bell-metal, in 
 which the wallower (cased in that part with iron plates) rests and turns round. 
 
 5, masonry supporting the inner gudgeon of the water-wheel and the 
 above-mentioned frame. 
 
 6, gudgeon of the wallower, which bears against the bell-metal step fixed 
 in the wall. This double support of the wallower is found to be necessary 
 in all mills which drive a number of heavy stampers. 
 
 Fig. 460 is the elevation of the pestle and press-frame, their furniture, the 
 mortars, and the press-pestles. 
 
 1, the six pestles. 
 
 2, cross-pieces between the two rails of the frame, forming, with these 
 rails, guides for the perpendicular motion of the pestles. 
 
 3, the two rails ; the back one is not seen. They are checked and bolted 
 into the standards, No. 12. 
 
 4, the tails of the lifts, corresponding with the wipers upon the wallower. 
 
 5, another rail in front, for carrying the detents which hold up the pestles 
 when not acting. It is marked 14, in fig. 464. 
 
 6, a beam a little way behind the pestles ; to this are fixed the pulleys for 
 the ropes, which lift and stop the pestles. It is represented by 16, in fig. 464. 
 
 7, the said pulleys with their ropes. 
 
 8, the driver which strikes the wedge that presses the oil. 
 
 9, the discharger, a stamper which strikes upon the inverted wedge, and 
 loosens the press. 
 
 10, the lower rail with its cross-pieces, forming the lower guides of the 
 pestles. 
 
 11, a small cog-wheel upon the wallower for turning the spatula, which 
 stirs about the oil-seed in the chauffer-pan. It has 28 teeth, and. is marked 
 No. 6, in fig. 464. 
 
 12, the four standards, mortised below into the block, and above into the 
 ioists and beams of the building. 
 
 13, the six mortars hollowed out of the block itself, and in shape pretty 
 much like a kitchen-pot. 
 
 14, the feet of the pestles rounded into cylinders, and shod with a great 
 lump of iron. 
 
 15, a board behind the pestles, standing on its edge, but inclining a little 
 backwards. There is such another in front, but not represented here. 
 These form a sort of trough, which prevents the seed from being scattered 
 about by the fall of the pestles, and lost. 
 
 16, the first press-box, (also hollowed out of the block,) in which the grain 
 is squeezed, after it has come for the first time from below the mill-stones. 
 
 17, the second press-box, at the other end of the block, for squeezing the 
 grain after it has passed a second time under the pestles. 
 
 1 8, frame of timber for supporting the other end of the wallower in the 
 same manner as No. 4, fig. 459. 
 
 19, small cog-wheel on the end of the wallower^ for giving motion to the 
 mill-stones; it has 28 teeth. 
 
©ZII. 9 C (01.01711 &> lOTKOO 3m.]LS 
 From 458 to 468 ^ 
 
 FI. 66 
 
 ,1 
 
 ■i 
 
 A 
 

AND MACHINIST. 449 
 
 20, gudgeon of the wallower, bearing on a bell-metal socket fixed in the wall. 
 
 21, vessels for receiving the oil from the press-boxes. 
 
 Fig. 461, Elevation and mechanism of the mill-stones. 
 
 1, upright shaft, carrying the great cog-wheel above, and the runner mill- 
 stones below in their frame. 
 
 2, cog-wheel of 76 cogs, driven by No. 19 of fig. 460. 
 
 3, the frame of the runners. 
 
 4, the innermost runner, or the one nearest the shaft. 
 
 5, outermost ditto, being farther from the shaft. 
 
 6, the inner rake, which collects the grain under the outer runner. 
 
 7, the outer rake, which collects the grain under the inner runner. In 
 this manner the grain is always turned over and over, and crushed in every 
 direction. The inner rake lays the grain in a slopes of which fig. 465 is a 
 section; the runner flattens it, and the second rake lifts it again, as is 
 marked in fig. 466 ; so that every side of the grain is presented to the mill- 
 stone, and the rest of the legger or nether mill-stone is so swept by them, 
 that not a single grain is left on any part of it. The outer rake is also fur- 
 nished with a rag of cloth, which rubs against the border or hoop that sur- 
 rounds the nether mill-stone, so as to drag out the few grains which might 
 otherwise remain in the corner. 
 
 8, the ends of the iron axle which passes through the upright shaft, and 
 through the two runners. Thus they have two motions : first, a rotation round 
 their own axis ; secondly, that by which they are carried round upon the nether 
 mill-stone, on which they roll. The holes in these mill-stones are made a 
 little wide ; and the holes in the ears of the frame, which carry the ends of 
 the iron axes, are made oval up and down. This great freedom of motion 
 is necessary for the runner mill-stones, because frequently more or less of 
 the grain is below them at a time, and they must therefore be at liberty to 
 get over it without straining, and perhaps breaking, the shaft. 
 
 9 and 10, the border or hoop which surrounds the nether mill-stone. 
 
 11 and 12, the nether mill-stone and masonry which support it. 
 
 Fig. 462, plan of the runner mill stones, and the frame which carries 
 them round. 
 
 1,1, are the two mill-stones. 
 
 3, 3, 3, 3, the outside pieces of the frame. 
 
 4,4,4, 4, the cross-bars of the frames, which embrace the upright shaft 5, 
 and give motion to the whole. 
 
 6, 6, the iron axis upon which the runners turn. 
 
 7, the outer rake. 
 
 8, the inner ditto. 
 
 Fig. 463 represents the nether mill-stone seen from above. 
 
 1, the wooden gutter which surrounds the nether mill-stone. 
 
 2, the border or hoop, about six inches high all round, to prevent any 
 seed being scattered. 
 
 3, an opening or trap-door in the gutter, which can be opened or shut at 
 pleasure ; when open, it allows the bruised grain, collected in and .shoved 
 along the gutter by rakes, to pass through into troughs placed below to 
 receive it. 
 
 4. . portion of the circle described by the outer runner. 
 
 5, portion of the circle described by the inner one. By these we sec that 
 llie two stones have different routes round the axis, and bruise more seed. . 
 
 6, the outer rake. 
 
 7, the inner ditto. 
 
 8, the SAveep, making part of the inner rake, occasionally let down fo5 
 
 2 G 
 
450 
 
 THE OPERATIVE MECHANIC 
 
 sweeping off all the seed when it has been sufficiently bruised* The pres- 
 sure and action of these rakes is adjusted by means of wooden springs, 
 which cannot be easily and distinctly represented by any figure. The 
 oblique position of the rakes (the outer point going foremost) causes 
 them to shove the grain inwards, or toward the centre, and at the same 
 time to turn it over somewhat in the manner as the mould-board of a plough 
 shoves the earth to the right hand, and partly turns it over. Some mills 
 have but one sweeper; and indeed there is great variety in the form and 
 construction of this part of the machinery. 
 
 Fig. 464j profile of the pestle-frame. 
 
 1, section of the horizontal shaft. 
 
 2, three wipers for lifting the pestles. 
 
 3, little wheel of 28 teeth for giving motion to the spatula. 
 
 4, another wheel which is driven by it, having 20 teeth. 
 
 5, horizontal axle of ditto. 
 
 6, another wheel on the same axle, having 13 teeth. 
 
 7, a wheel upon the upper end of the spindle, having 12 teeth. 
 
 8, two guides, in which the spindle turns freely, and so that it can be 
 shifted higher and lower. 
 
 9, a lever, movable round the piece No. 1 4, having a hole in it at 9, 
 through which the spindle passes, turning freely. The spindle has in this 
 place a shoulder, which rests on the border of the hole 9, so that by the 
 motion of this lever the spindle may be disengaged from the wheel- work at 
 pleasure ; this motion is given to it by means of the lever 10, 10, movable 
 round its middle. The workman employed at the chauffer pulls at the rope 
 10, 11, and thus disengages the spindle and spatula, 
 
 11, a pestle seen sidewise. 
 
 12, the left of ditto. 
 
 13, the upper rails, marked No 3, in fig. 460. 
 
 14, the rail marked No. 5, in fig. 460. To this are fixed the detents, 
 which serve to stop and hold up the pestles. 
 
 15, a detent, which is moved by a rope at its outer end. 
 
 16, a bracket behind the pestle, having a pulley through which passes 
 the rope going to the detent 15. 
 
 17, the said pulley. 
 
 18, the rope at the workman’s hand, passing through the pulley 17, and 
 fixed to the end of the detent 15. 
 
 This detent naturally hangs perpendicular by its own weight. When the 
 workman wants to stop a pestle, he pulls at the rope 18, during the rise of 
 the pestle. When this is at its greatest height, the detent is horizontal, and 
 prevents the pestle from falling, by means of a pin projecting from the side 
 of the pestle, which rests upon the detent, the detent itself being held in 
 that position by hitching the loop of the rope upon a pin at the workman’s 
 hand. 
 
 19, the two lower rails, marked No. 10, fig. 460. 
 
 20, great wooden, and sometimes stone, block, in which the mortars are 
 formed, marked No. 21, fig. 460. 
 
 21, vessel placed below the press-boxes for receiving the oil. 
 
 22, chauffer, or little furnace, for warming the bruised grain. 
 
 23, backet in the front of the chauffer, tapering downwards, and opening 
 below in a narrow slit. The hair-bags on which the grain is to be pressed 
 after it has been warmed in the chauffer, are filled by placing them in this 
 backet. The grain is lifted out of the chauffer with a ladle, and put into 
 these bags ; and a good quantity of oil runs from it through the slit at the 
 bottom into a vessel set to receive it. 
 
Al^O JWAckiNIST. 
 
 451 
 
 24 , the spatula attached to the lower end of the ipindle, and turning 
 teund aniortg the grain in the chauffw-pan, and thus preventing it from 
 sticking to the bottom or sides, and getting too much heat. 
 
 The first part of the process is bnlisiiig the seed under the 
 runnef-stones ; that this may be more expeditiously done, 
 one of the runners is set about two-thirds of its own thickness 
 nearer the shaft than the other ; thus they have different 
 treads, and the grain, which is a little heaped tow’ards the 
 centre, is thus bruised by both. The inner rake gathers it 
 up under the outer stone into a ridge, of which the section is 
 represented in fig. 465 ; the stone passes over it, and flattens it. 
 It is gathered up again into a ridge, of the form of fig. 466, 
 under the inner stone by the outer rake, which consists of 
 two parts ; the outer part presses close on the wooden 
 border which surrounds the nether stone, and shoves the seed 
 obliquely inwards, while the inner part of this rake gathers 
 up what has spread towards the centre. The other rake has 
 a joint near the middle of its length, by which the outer half 
 of it can be raised from the nether stone, while the inner 
 half continues pressing on it, and thus scrapes off the moist 
 paste. When the seed is sufficiently bruised, the miller lets 
 down the outer end of the rake ; this immediately gathers the 
 whole paste, and shoves it obliquely outwards to the wooden 
 rim, where it is at last brought to a part that is left unboarded, 
 and it falls through into troughs placed to receive it. These 
 troughs have holes in the bottom, through which the oil drips 
 all the time of the operation. This part of the oil is directed 
 into a particular cistern, being considered as the purest of the 
 whole, having been obtained without pressure, by the mere 
 breaking of the hull of the seed. 
 
 In some mills this operation is expedited, and a much 
 greater quantity of this best oil is obtained, by having the 
 bed of masonry which supports the legger formed into a little 
 furnace, and gently heated ; but the utmost care is necessary 
 to prevent the heat from becoming considerable, lliis, 
 enabling the oil to dissolve more of the fermentable substance 
 of the seed, exposes the oil to the risk of growing soon very 
 rancid ; and in general it is thought a hazardous practice, 
 and the oil does not bring so high a price. 
 
 When the paste comes from under the stones, it is put into 
 the hair-bags, and subjected to the first pressing. The oil 
 thus obtained is also esteemed of the first quality, scarcely 
 inferior to the former, and is kept apart (the great oil-cistem 
 betog divided into several portions by partitions.) 
 
 The oil-cakes of this pressing are taken out of the bags, 
 broken to pieces, and put into mortars for the first stamping. 
 
 2g2 
 
THE OPERATIVE MECHANIC 
 
 m 
 
 Here the paste is again broken down, and the parenchyma of 
 the seed reduced to a fine meal 3 thus free egress is allowed 
 to the oil from every vesicle in which it is contained. But it 
 is now rendered much more clammy by the forcible mixture 
 of the mucilage, and even of the finer parts of the meal. 
 When sufficiently pounded, the workman stops the pestle of 
 a mortar, when at the top of its lift, and carries the contents 
 of the mortar to the first chauffer-pan, where it is heated to 
 about the temperature of melting bees’ -wax, (this, we are told, 
 is the test,) and all the while stirred about by the spatula. 
 From thence it is again put into hair-bags, in the manner 
 already described ; and the oil which drops from it during 
 this operation is considered as the best of the second quality, 
 and in some mills is kept apart. The paste is now sub- 
 jected to the second pressing, and the oil is that of the second 
 quality. 
 
 All this operation of pounding and heating is performed by 
 one workman, who has constant employment by taking the 
 four mortars in succession. The putting into the bags, and 
 conducting the pressing, gives equal employment to another 
 workman. 
 
 In the mills of Picardy, Alsace, and most of Flanders, the 
 operation ends here ; and the produce from the chauffer is 
 increased, by putting a spoonful or two of water into the pan 
 among the paste. 
 
 But the Dutch take more pains. They add no water to 
 the paste of this their first stamping 3 they say that this 
 greatly lowers the quality of the oil. The cakes which result 
 from this pressing, and are then sold as food for cattle, are 
 still fat and soft. The Dutch break them down, and subject 
 them to the pestles for the second stamping 5 these reduce 
 them to an impalpable paste stiff like clay. It is lifted out, 
 and put into the second chauffer-pan 3 a few spoonfuls of 
 water are added, and the whole kept for some time as hot as 
 boiling water, and carefully stirred all the time. From thence 
 it is lifted into the hair-bags of the last press, subjected to the 
 press, and a quantity of the lowest quality is obtained, sufficient 
 for giving a satisfactory profit to the miller. The cake is now 
 perfectly dry and hard, like a piece of board, and sold to the 
 farmers. Nay, there are small mills in Holland which have 
 no other employment than extracting oil from the cakes which 
 they purchase from the French and Brabantees : a clear indi- 
 cation of the superiority of the Dutch practice. 
 
 The nicety with which that industrious people conduct all 
 their business is remarkable in this manufacture. 
 
 In their oil-cisterns the parenchymous part, which unavoid- 
 
AND MACHINIST. 
 
 453 
 
 ably gets through, in some degree,' in every operation, gradu- 
 ally subsides, and the liquor, in any division of the cistern, 
 comes to consist of strata of different degrees of purity. The 
 pumps which lift it out of each division are in pairs ; one 
 takes it up from the very bottom, and the other only from 
 one half the depth. The last only is barrelled up for the 
 market, and the other goes into a deep and narrow cistern, 
 where the dreg again subsides, and more pure oil of that 
 quality is obtained. By such careful and judicious practice, 
 the Dutch not only supply themselves with this important 
 article, but annually send considerable quantities into the 
 very provinces of France and Flanders, where they buy 
 the seed from which it is extracted. When we reflect on the 
 high price of labour in Holland, on the want of timber for 
 machinery, on the expense of building in that country, and 
 on the enormous expense of wind-mill machinery, both in 
 the first erection and the subsequent wear and tear, it must 
 be evident that oil-mills erected in England on waterfalls, 
 and after the Dutch maimer, cannot fail of being a great 
 national advantage. The chatellenie or seigneurie of Lille 
 alone makes annually between 30,000 and 40,000 barrels, each 
 containing about 26 gallons. 
 
 What is here delivered is only a sketch. Every person 
 acquainted with machinery well understands the general move- 
 ments and operations ; but the intelligent mechanic well 
 knows that operations of this kind have many minute circum- 
 stances which cannot be described, and which, nevertheless, 
 may have a great influence upon the whole. The rakes in 
 the bruising-mill have an office to perform which resembles 
 that of the hand, directed by a careful eye and unceasing 
 attention. Words cannot convey a clear notion of this ; and 
 a mill constructed from the best drawings, by the most skilful 
 workman, may gather the seed so ill, that the half of it shall 
 not be bruised after many rounds of the machinery. This 
 produces a scanty return of the best oil, and the mill gets a 
 bad character ; the proprietor loses his money, is discouraged, 
 and gives up the work. There is no security but by pro- 
 curing a Dutch millwright, and paying him with the liberality 
 of Britons. Such unhoped-for tasks have been performed of 
 late years by machinery, and mechanical knowledge and 
 invention is now so generally diffused, that it is highly pro- 
 bable we should soon excel our teachers in the branch ; 
 but this very diffusion of knowledge, by encouraging specu- 
 lation among the artists, makes it a still greater risk to erect 
 a Dutch oil-mill, without having a Dutchman, acquainted 
 with its most improved present form, to conduct the work 
 
454 
 
 THE OPERATIVE MECHANIC 
 
 COLOUR AND INDIGO MILLS. 
 
 The reducing of earths, vegetable substances, and metallic 
 oxyds to an impalpable powder, is still in a great degree 
 effected by manual labour, by moving a heavy stone with a 
 smooth surface, called a muller, upon a slab of the same 
 material. To effect this work upon a larger scale, and to 
 i^ecure the workman from the ill effects of the poisonous and 
 noxious vapours of the paint, which is not unfrequently 
 ground with litharge of lead, Mr. Rawlinson, of Derbj^ has 
 invented a machine which we here describe. It is repre^ 
 sented in fig. 467. 
 
 A, the roller, or cylinder, made of any kind of black marble. Black marble 
 is esteemed the best, because it is hardest, and takes the best polish. B, the 
 concave muller, covering one-third of the roller, and of the same material, 
 fixed in a wooden frame 6, which is hung to the frame E at i i. C is a piece 
 of iron, about an inch broad, to keep the muller steady, and is fixed to the 
 fi-ame with a joint at f. The small binding screw witli a fly-nut, which 
 passes through the centre of the iron plate at c, is for the purpose of laying 
 niore pressure upon the muller, if required, as well as to keep it steady. 
 D is a taker-off, made of a clock-spring, about half an inch broad, and fixed 
 similar to a frame-saw in an iron frame K, in an inclined position to the 
 roller, and turning on pivots at rf rf. G is a slide-board to draw out occa- 
 sionally, to clean, &c. if any particles of paint should fall from the roller ; it 
 also forms itself for the plate H, to catch the colour as it falls from the 
 taker-off. F is a drawer for the purpose of containing curriers’ shavings, 
 which are used for cleaning paint-mills. E is the frame. 
 
 Previously to putting the colour in the mill, it must be 
 pulverized in a mortar, covered in the manner of the chemists, 
 when they levigate poisonous drugs, or rather in an improved 
 mill, used at Manchester, by Mr. Charles Taylor, for grinding 
 indigo in a dry state, a drawing and description of which i^ 
 annexed. After undergoing this process of dry-grinding, 
 which is equally necessary for the marble slab now in use, it 
 is mixed with either oil or water, and is with a spatula, or 
 palette-knife, put on the roller, near to the top of the concave 
 muller. Motion being given to the roller, it, without any 
 difficulty, carries the colour under the muller, and in a few 
 revolutions spreads it equally over the surface. When ground 
 sufficiently, it is taken off, both cleanly and expeditiously, by 
 the taker-off described, which, for that purpose, is held against 
 the roller, while the roller is turned the reverse way. The 
 muller only requires to be cleaned when the workman changes 
 the colour, or ceases from the operation ; it is then turned 
 back, being hung on pinions to the frames at i i, and is 
 cleaned with a palette-knife or spatula j afterwards a handful 
 
AND MACHINIST, 455 
 
 of curriers* shavings is held against the roller, which, in two 
 or three revolutions, cleans it effectually. 
 
 The roller of Mr. Rawlinson*s machine is sixteen inches 
 and a half in diameter, and four inches and a half in breadth 5 
 and the concave muller which it works against covers one- 
 third of the roller. It is therefore evident, that, with this 
 machine, he has seventy-two square inches of the concave 
 marble muller in constant work on the paint, and that he can 
 bring the paint much oftener under the muller in a given 
 space of time than with the common pebble muller, which, 
 being seldom more than four inches in diameter, has scarcely 
 sixteen square inches at work on the paint, whereas the con- 
 cave muller has seventy-two. 
 
 The quantity ground at once in the mill must be regulated 
 by the degree of fineness of which it is required, that which 
 is the finest requiring the smallest quantity to be ground at 
 once. The time requisite for grinding is also dependant upon 
 the state of fineness ; but Mr. Rawlinson observes, that his 
 colour-grinder has ground the quantity of colour which used 
 to serve him per day in three hours ; the colour also was 
 more to his satisfaction, and attended with less waste. 
 
 When the colour is ground, Mr. Rawlinson recommends, 
 instead of drawing the neck of the bladder up close in the act 
 of tying it, to insert a slender cylindrical stick, and bend the 
 bladder close round it ; this, when dry, will form a tube or 
 pipe, through which, when the stick is withdrawn, the colour 
 may be squeezed as wanted, and the neck again closed by 
 replacing the stick. This is not only a neater and much 
 more cleanly mode than the one usually adopted, that of per-» 
 forating the bladder, and stopping the hole with a nail, or, 
 what is more common, leaving it open, to the detriment of the 
 colour; but the bladder, not being injured, maybe repeatedly 
 used for fresh quantities of colour. The barrel of a quill may 
 be inserted in the neck of the bladder, as a substitute for the 
 stick, and the end being cut off, may be closed by a small 
 piece of wood. 
 
 In order to make the whole of the process of colour-grinding 
 complete, we shall here insert a description of the indigo-mill 
 used by Mr. Charles Taylor, of Manchester, for grinding 
 indigo in a dry state, which may with equal advantage be 
 similarly employed for colours. It k represented in figs. 468 
 and 468*. 
 
 L, fig. 468, represents a mortar, made of marble or hard stone j one made 
 in the common way will answer. M. a muller, or grinder, nearly in the 
 form of a pear ; in the upper part of which an iron axis is firmfy fixed. 
 
456 
 
 THK OPERATIVE MECHANIC 
 
 whicli axis at the parts N N turns in grooves or slits, cut in two pieces of 
 oak, projecting horizontally from a wall, and when the axis is at work are 
 secured in the grooves by iron pins O O. P, the handle, which forms 
 a part of the axis, and % which the grinder is worked. Q, the wall in 
 which the oak pieces N N are fixed. R, a weight, which may occasionally 
 be added if mo^e power is wanted. 
 
 Fig. 468% shows the muller or grinder, with its axis separate from the 
 other machinery ; its bottom should be made to fit the mortar. S is a 
 groove cut through the stone. 
 
 On grinding the indigo, or similar substance, in a dry state, 
 in this mill, the muller being placed in the mortar and 
 secured in the oak pieces by the pins, the indigo to be ground 
 is thrown above the muller into the mortar; on turning the 
 handle of the axis, the indigo, in lumps, falls into the groove 
 cut through the muller, and is thence drawn under the action 
 of the muller, and propelled to its outer edge within the 
 mortar, whence the coarser particles again fall into the groove 
 of the muller and are again ground under it; which operation 
 is continued till the whole of it is ground to an impalpable 
 powder ; the muller is then easily removed, and the colour 
 taken out. 
 
 A wood cover in halves, with a hole for the axis, is usually 
 placed upon the mortar, during the operation, to prevent 
 anv loss to the colour, or bad effects to the operator. 
 
 POTTERY. 
 
 The clays best adapted for the manufacture of earthen^ 
 ware are excavated in Dorsetshire, and the next in quality in 
 Devonshire. 
 
 The natural compounds, palled clays, consist generally of 
 pure clay, or alumine, combined with either silex or lime, 
 and sometimes magnesia, and the oxyd of iron. The pre- 
 sence of the magnesia may easily be detected by its imparting 
 a soapy feel ; and the iron by the clay burning to different 
 shades of red, proportionate to the quantity it contains. The 
 magnesia has obtained the name of soap-rock, and a marked 
 variety of it steatite. 
 
 The clay is first put into a trough about five feet long, by 
 three wide, and deep, with a certain proportion of water, 
 and subjected to the process called blunging ^ which is obvi- 
 ously akin to blending, or mixing. This is performed with a 
 long piece of wood formed in the shape of a blade at one end, 
 and with a cross-handle at the other. The bladed end is put 
 into the trough, and moved backwards and forwards, up and 
 
AND MACHINIST. 
 
 457 
 
 down, with violence, till the clay be broken and well levigated. 
 The coarser particles of the clay sink to the bottom of the 
 trough, while the finer parts remain suspended in the 
 solution 5 and clay is continued to be added until the solu- 
 tion has acquired the consistence of thick cream. This thick 
 liquid is passed into a large tub, and afterwards through 
 fine hair and silk lawn sieves, and then mixed with certain 
 proportions of a liquid of ground calcined flints and Cornish 
 stone, which, likewise, have been passed through silk lawn 
 sieves. 
 
 The china clay, which is used in every kind of earthenware 
 except the cream colour, is sometimes put into the mass, and 
 blunged with it at other times it is put into another tub, 
 and blunged separately, and is then mixed in proper propor- 
 tions with the other slip. 
 
 The slip is now passed into another large stone or wood 
 cistern, and the parts, which have not been previously, are 
 now added, and the whole is passed through fine lawn into a 
 reservoir, from whence it is pumped upon the slip-kiln. 
 
 When a steam-engine is used, the clay is thrown into a 
 vertical cast-iron cone, about two feet wide at top, and six 
 feet deep. Inside of this cone are fixed strong knives, having 
 a spiral arrangement and inclination, and radiating towards 
 the centre. In the centre of these is worked a perpendicular 
 shaft, with similar radiating knives, so that the knives, by 
 the revolution of the shaft, cut in pieces every thing that is 
 thrown! into the cone, and force downward, agreeably to the 
 nature of the screw, whatever may be put in till it is dis- 
 charged through an orifice at the bottom. 
 
 The clay, thus reduced to powder, is next subjected to 
 the process of blunging. For this purpose it is thrown 'into 
 a large circular vat, or cistern, having a strong vertical shaft 
 of wood, with arms formed like a gate as radii, worked by 
 the power of the steam-engine. The vat is nearly filled with 
 proper proportions of water and clay, which, by the rapid 
 motion of the shaft, becomes well levigated and mixed; 
 clay or water being added until the liquid is of the consist- 
 ence of cream. The liquid is then passed along several 
 trunks, at the end of each of which is fixed a fine hair or 
 lawn sieve. These sieves have a quick horizontal motion 
 communicated to them by crank machinery, which causes the 
 slip to pass through into a large reservoir, where it remains 
 till pumped upon the kiln. 
 
 The flint in its crude state is the common flint used for 
 striking fire, which consists principally of pure silex. The 
 
458 
 
 THE OPERATIVE MECHANIC 
 
 method of calcining it is, by placing it in a email conical 
 kiln, about nine feet deep, and altogether not much unlike 
 that used to burn limestone. When red-hot it is taken out 
 of the kiln and thrown into cold water, in order to lessen its 
 aggregation, and make it easier to reduce to powder. The 
 flint is next broken into pieces, either by manual labour, or 
 machinery. Where manual labour is employed one man is 
 found adequate to break per diem enough to supply two 
 flint-pans, 12 feet diameter. 
 
 In the other process the flints are put on a strong iron 
 grating, and are struck by large hammers, moved by ma- 
 chinery, till they be so reduced as to fall through the grating 
 into a cavity, from whence they are taken to the flint-mill. 
 
 The Jiint-mill consists of a large circular vat, about 30 
 inches deep, with a step fixed in the centre at the bottom 
 for the axis of a vertical wood or iron shaft. The upper 
 end of the shaft is surmounted by a large crown cog-wheel, 
 to which the moving power is applied. The lower end has, 
 at right angles, four leaves, or paddles, like arms, upon 
 which are fixed chert-stones. Large blocks of chert-stone 
 are also placed in the vat. The flints being put into the vat, 
 the whole is covered with water, to prevent any dust from 
 arising, which had formerly a very injurious effect. Power 
 being communicated to the shaft, the chert-stones are car- 
 ried round with considerable velocity, and the calcined flints, 
 being of a very fragile nature, are, by their reciprocal action, 
 reduced to an impalpable powder. 
 
 This semi-fluid is put into another vat, that has a similar 
 vertical shaft, and when a large quantity of water has been 
 introduced, the power is applied and the whole is well 
 levigated. In this process, the weighty particles sink to the 
 bottom, and the finest remain in suspension ; which are then 
 passed into a reservoir that has certain apertures for drawing 
 off the surplus water, till it has subsided to a state fit for 
 the potter’s use. This is a very important process, and is 
 attended with some difficulty. It is at present best per- 
 formed by Mr. Sampson Hanley, of Sandon Mill. 
 
 The manufacturer should be very choice in selecting the 
 stones to be employed in the grinding ; for should they con- 
 tain calcareous carbonates, such parts will be abraded, and 
 by mixing with the silicious matter will, in a subsequent 
 process, prove a serious injury. 
 
 A few years ago a loss to the amount of several thousand 
 pounds was experienced by some manufacturers, who had 
 very injudiciously purchased stones that had been ground by 
 
AND MACHINIST. 
 
 459 
 
 a person ignorant of the art, and who had employed stones 
 for the grinding containing carbonate of lime. 
 
 The average weight of an ale pint measure of the pulp of 
 flint is 32 oz. ; and of clay 24 oz. 
 
 In some manufactories the pulps are mixed together in a 
 large vat, by a process similar to that first described of mix- 
 ing the clay with the water. But however the mixing be 
 accomplished, great attention must be paid to the relative 
 specific gravity of each fluid, and more of the solution of the 
 flint, or the clay, must be added, till a pint of the mixture 
 weighs the determined number of ounces. It is by the con- 
 sistence and weight of these materials, that the manufacturer 
 is enabled to ascertain, the proper proportions requisite for 
 each kind of pottery ; and it is from these that he can calcu- 
 late, whether there be a probability of making any improve- 
 ment that will yield him a profitable return. 
 
 When the proper proportions of slop clay and flint have 
 been well blunged together, the liquid is pumped out of the 
 reservoir on the top of the slip-kiln. 
 
 The slip-kiln is a kind of trough formed of fire-bricks, of 
 various sizes, from 30 to 60 feet in length, by from 4 to 6 
 in breadth, and about }2 inches iq depth. Flues from the 
 fire-places pass under these troughs, and the bricks of which 
 they are formed being bad conductors of heat, a slow and 
 advantageous process of evaporation is carried on, which gives 
 uniform consistence to the mass. 
 
 The porcelain clay is never allowed to boil, but is carefully 
 evaporated at a slow heat on a plaster-kiln ; the gypsum 
 being run on old moulds pulverized, and thus forming a level 
 surface. 
 
 The slip-maker carefully attends to the evaporation, and 
 at proper intervals turns over with a paddle the thickened 
 mass from one end to the other, else the part nearest to the 
 bricks would become hard, while the surface were fluid. To 
 regulate the heat three different thicknesses of bricks are 
 employed, the thickest being placed nearest to the fire-place, 
 where is the greatest excess of heat. 
 
 When a sufficient quantity of the moisture is evaporated, 
 which is indicated by the cessation of apparent effervescence, 
 or the absence of air-bubbles on the surface of the mass, the 
 composition, still called clay, is removed to the flags. 
 
 If the evaporation were continued longer the clay could 
 not be formed into the required shapes, either on the wheel, 
 or by the vat, but would be, W’hat is called knotty, lumpy. 
 
 The clay is cut out of the kilns in square masses, by means 
 
400 
 
 TIIK OPKRATIVE MECHANIC 
 
 of spades, and is thrown into a heap, where is attained an 
 uniform temperature of cold and moisture. The longer it 
 can lie after coming off the kiln the better it will be; but the 
 time is arbitrarily varied by the want of room, of time, or 
 of capital. 
 
 When the clay is first taken off the kiln, it is, partly from 
 the air-bubbles remaining in it, and partly from the non- 
 dissipation of the heat requisite for evaporation, too soft to 
 be worked. On this account it is well incorporated together, 
 or tempered, by beating with wooden mallets. It is then 
 cut into small pieces with a paddle, not much unlike a spade, 
 and from the paddle each piece is, with all the force of the 
 workman, propelled upon the mass. These two operations 
 are repeated until a proper consistence pervades, and the 
 whole is supposed to be well-tempered. 
 
 Whe*i the clay is required for the thrower the process of 
 slapping follows next. This is performed by a strong man, 
 who places a large mass, about half a hundred-weight, upon 
 a convenient and strong bench. He then, wdth a thin brass 
 wire, cuts the mass through, and taking up the piece thus 
 cut off, he, wdth his utmost strength, casts it down again on 
 the mass below ; and continues the operation as long as is 
 considered necessary. 
 
 This is a very laborious process, and is absolutely neces- 
 sary to drive out any air-bubbles which may happen to remain 
 in the mass after it has been beaten : for should any be left 
 in the clay the pieces on being fired would blister and spoil, 
 owing to the rarefaction of the air by the heat. On this very 
 important account, the process is continued until the mass, 
 wherever cut by the brass wire, exhibits a surface, perfectly 
 smooth, and homogeneous. 
 
 In several of the largest manufactories the labour of slap- 
 ping the clay is superseded by mechanical contrivance. A 
 quantity of the mass from the slip- kiln, w hen rather cold, is 
 thrown into a large conical iron vessel, (similar to that em- 
 ployed in breaking the clay,) with strong knives fixed in it, 
 with a given inclination, with corresponding knives radiating 
 from a vertical shaft, moved by the steam-engine wdth a slow 
 and regular motion. By these means, all the clay put into 
 the cone is very minutely separated, and pressed down, as 
 by a screw, so that the mass just cut, and divided, is instantly 
 squeezed together again, and is then similarly affected by 
 other knives below. At the bottom of the cone on one side is 
 a quadrangular aperturej through which the clay is gradually 
 forced, and is by a thin brass wire cut into brick-shaped 
 
AND MACHINIST. 
 
 461 
 
 pieces of from 50 to 60 pounds weight. Sometimes these 
 masses are for particular purposes returned into the cone, and 
 undergo the process a second time. 
 
 fTedging the clay is a similar process, though never omitted 
 by the presser, or squeezer, however well it may have been 
 beaten by the slip-maker. The presser cuts off, with a thin 
 brass wire, a piece of clay from the mass, which he slaps 
 forcibly between the palms of his hands, and then with great 
 violence throws it on the board; continuing the operation 
 until the commixture is so complete that there is no proba- 
 bility of any air-bubbles remaining. If one of the two first 
 pieces of clay had been white, and the other black, the mass, 
 after undergoing these processes, would present wherever cut 
 a uniform grey colour. 
 
 It is owing to the mass being properly wedged that that 
 consistency and tenacity is obtained, which enables the 
 workman to employ it with facility and confidence in the 
 fabrication of the different pieces of pottery which he has to 
 make. The clays for vessels require different degrees of 
 wedging ; and some kinds require much more careful and 
 continued wedging than others. 
 
 The clay may now be considered ready for the thrower. 
 The throwing-wheel, or, with greater propriety, the 
 engine, consists of a large vertical wheel; having a winch or 
 handle affixed to it, and a groove on the rim for the intro- 
 duction of a cord. The whole is fixed upon a strong movable 
 plank, by which the cord can be slackened or tightened at 
 pleasure, and then upon a frame iiea,rly triangular, or half- 
 oval, and about 30 inches in height, with a broad ash hoop 
 placed edgewise on the fore part, about six inches deep. 
 
 In the centre of this frame is a vertical spindle, with its 
 low'er end fitted and working in a step. A little above this 
 is a pulley, with grooves for three speeds of the propelling- 
 power, connected with the throwing-wheel by means of a 
 cord or belt; and a little higher up is a pivot turned to fit 
 and work in a collar-step. On the upper end is a stout 
 wooden circular top, which revolves horizontally, and is in 
 diameter about seven inches; and other tops of different 
 diameters are in readiness to be fixed on, according to the 
 intended size of the vessel to be made. 
 
 The engine is set in motion by manual labour, applied at 
 the winch, and another man, called the halier, cuts with a 
 thin piece of brass wire a piece of clay from the mass on the 
 bench, and forms it into a ball, which he gives to the thrower, 
 if china is to be made, the bailer, previously to forming the 
 
462 
 
 THE OPERATIVE MECHANIC 
 
 clay into a ball, breaks it in two, and violently slaps it toge- 
 ther between the palms of his hands. The thrower forcibly 
 throws the ball down upon the horizontal revolving top of 
 the engine, and dipping his hands frequently into water, to 
 prevent the clay adhering to them, fashions it into a long 
 thin column, which he again forces down into a lump, and 
 continues to repeat the operation until he is satisfied that 
 the air-bubbles, which might have remained in the clay after 
 the processes of slapping and balling, are dispelled. 
 
 Tiie thrower now directs the speed of the engine to be 
 lessened, and with his fingers, which he frequently dips in 
 water, he gives the first form to the vessel; then with 
 different profiles^ or rihs^ he forms the inside of the vessel 
 into w^hatever shape may be required, and smoothes it by 
 removing the slimy, or inequalities. 
 
 If a number of vessels of the same size be required, the 
 thrower has a peg placed as a gauge, which serves to direct 
 him in the width and depth; and when the vessel has two 
 diameters, as the neck and body in a jug, he has two pegs to 
 guide him. 
 
 The thrower forms all circular vessels in this manner; and 
 he employs different sized ribs to finish the shapes, or swell 
 of the edge, &c. When he has thus given the first form to 
 the clay, he cuts the vessel from the head of the engine, by 
 passing a thin brass wire through the lowest part of the clay, 
 which separates it, and allows it to be easily lifted off, and 
 placed by the bailer on a long board or shelf, where it is 
 left to dry a little preparatory to being turned, or properly 
 smoothed and shaped. 
 
 Where large vessels are made, and the power of a steam- 
 engine applied, according to Mr. J. Wedgwood's method, a 
 pair of vertical cones is used, the apex of the one being 
 opposite to the vertex of the other. One of these cones is 
 driven directly by the steam-engine, and transmits motion 
 to the other by means of a broad belt or strap of leather, 
 which is always equally tight in any and every part of the 
 cones, because they are equal and reversed ; but it is plain, 
 that the speed of the driven cone will vary much according 
 as the belt is at the top or the bottom of the driving cone. 
 When the belt is at the bottom or thinnest part of the driving 
 cone, the driven cone moves very slowly ; as the belt is made 
 to ascend, the speed of the driven cone increases, and ulti- 
 mately attains its maximum when the belt is at the top. A 
 strap is attached from the driven cone to the spindle of the 
 throwing-engine, and the speed is varied at the thrower’s 
 
AND MACHINIST. 465 
 
 pleasure, by a boy working a directing winch. When the 
 article is finished, the machine is thrown out of geer. 
 
 For forming saucers, and other small circular articles, there 
 has been recently introduced a small vertical shaft, called a 
 jigger, on the top of which is a turned head, suited to receive 
 the mould on which the saucers, &c. are to be formed. 
 
 When the clay is in one peculiar state, called the green 
 state, it is the most suitable and proper for performing to the 
 greatest advantage the remaining operations and processes of 
 turning, handling, trimming, &c. 
 
 The tuming’dathe is the same as used by wood -turners. 
 The end of the spindle, outside the headstock, has a screw 
 tliread, upon which is screwed chocks of wood, of a tapered 
 form, and of different diameters, according to the size of the 
 interior of the articles of pottery to be turned. The turner 
 stands very steady, and receives from an attendant the vessel 
 to be turned, which he fixes upon the chock, and then with a 
 tool presses the edges close down. 
 
 The tools are of different sizes, from one quarter of an 
 inch to two inches in breadth, and six inches in length, 
 made of thin iron, like hoop-iron, the end for cutting being 
 turned up about a quarter of an inch, and ground sharp. 
 
 Motion being commmuiiicated to the lathe, the turner 
 applies his tool or tools to the various parts of the surface 
 that require reduction of substance, either as regards thick- 
 ness, or the suitable shapes of rims, feet, &c. When this is 
 completed, a contrary motion is communicated to the spindle, 
 during which the turner applies the flat part of his tool to 
 the vessel, and by gentle pressure gives it a smooth surface, 
 and solid texture. 
 
 In the turning-lathes moved by steam some particular 
 arrangements are made. A horizontal shaft runs the whole 
 length of the room ; and opposite to each lathe is a drum, 
 which communicates motion to a set of pulleys, of various 
 sizes, fixed on an arbor or shaft, by means of a leather belt. 
 Upon this arbor, or shaft, is a loose pulley, connected by a 
 crossed belt with a small pulley fixed on the spindle of the 
 lathe, which evidently will, whenever the strap from the 
 drum is directed upon the loose pulley, receive a retrograde 
 motion. The spindle has pulleys counter to those fitted on 
 the arbor, and as they are ever revolving, the directing of the 
 belt from them to the spindle, by a guide moved by the 
 workman’s foot, will increase or diminish the speed during 
 the turning of the vessel under operation; and when it is 
 finished, by moving the drum-strap on another pulley, retro- 
 
4G1 
 
 TIIK OPERATIVE MECHANIC 
 
 grade motion is given, during which the turner smooths off 
 his article, as before noticed. 
 
 The engine-lathe is of the kind employed to give unto 
 circular articles of hardware a milled edge ; consequently, it 
 differs from the other, or common lathe, in the formation of 
 the end of the spindle, and the appendages to the headstock. 
 Certain thin circular plates of steel, into whose edges are cut, 
 at regular intervals, and of different degrees of breadth, deep 
 incisions, are made to screw very firmly on the end of the 
 spindle above the chock. The collar-step of the spindle is 
 so fitted that it can be effected by a screw pin, which gives it 
 the requisite horizontal shuffling motion. Opposite to the 
 steel-plate is fixed an iron piece that fits into the incisions. 
 The turner’s tools are filed to give the particular form to the 
 designed ornament, and the vessel, having been previously 
 turned in the plain way, receives a shuffling motion back- 
 wards and forwards as the spindle slowly revolves, and only 
 when the incision admits the piece of iron will the vessel be 
 in contact with the tool of the workman. When the iron is 
 against the rim the surface remains untouched by the tool. 
 Numerous very elegant and curiously indented porcelain arti- 
 cles are formed by the engine-lathe. The black Egyptian 
 circular tea-pots will exemplify every species of engine-lathe 
 turning. 
 
 As the vessels as soon as turned are in the best green 
 state, they are, as soon as possible, passed to the handler, 
 who fixes the spouts, handles, and all other requisite appen- 
 dages. Such spouts, handles, or appendages, as are in any 
 way curved, oval-shaped, or ornamented, are formed in moulds 
 of two or more parts, as will be seen hereafter when speaking 
 of squeezing. 
 
 For handles, and some other articles of appendage, a press 
 is used, consisting of an iron cylinder, six inches wide, and 
 ten inches deep. This cylinder has a strong bottom, with an 
 aperture in the centre, to which is made to fit differently 
 shaped plugs. It has a piston acting by a screw, that works 
 in a bent iron bow, fastened to the block on which the cylin- 
 der rests. The aperture being supplied with a plug of the 
 required form, some clay is put into the cylinder, and the 
 piston forced down, by turning the screw, which causes 
 the clay to protrude through the aperture in the shape 
 required. The workmen cut it into lengths, as wanted, and 
 bend it into the required form, and when sufficiently dry, 
 affix it to the vessel by slip. Slip is likewise used to affix ail 
 other appendages. When a tube is wanted, a pin is fixed 
 
AND MACHINIST. 
 
 466 
 
 in the clay that protrudes through the aperture of the cylin- 
 der, a pin is fixed above the centre of the plug. The vessel, 
 being allowed a short time to dry, is cleared of all the super- 
 fluous clay by a knife. The vessel is then trimmed with 
 other tools, and the whole of the joints cleaned off with a 
 moist sponge, which, while it carries off all excrescences, 
 gives to the whole uniform moisture. 
 
 We shall, previously to mentioning the process of squeez- 
 ing, lake notice of the modeller and the mould-maker, whose 
 occupations are very distinct branches of the art. 
 
 The modeller has great scope for the exertion of natural 
 and acquired ability, taste, and ingenuity : for on him depends 
 the elegance, size, figure, adaptation, and correct arrange- 
 ment of suitable ornaments. His business consists in taking 
 a large lump of well-tempered clay, and modelling it, by 
 continued carvings, with a sharp narrow-bladed knife, into 
 the rough figure : he then commences the trimming process, 
 by removing all excrescences, inserting any additions, and 
 finally with a great variety of suitable tools, made of ivory, 
 wood, or metal, gives to the whole the several touchings and 
 retouchings requisite for finishing. 
 
 The modellers of the present day have attained much 
 excellence, and as a proof we need only to state, that many 
 who have seen the Portland or Barberini vase (for model- 
 ling of w'hich Mr. Wedgwood is said to have paid Webber 
 the enormous sum of four hundred pounds) declare, that any 
 good modeller would now execute the whole himself in less 
 than a month, and with a proper assistant in a fortnight. 
 The branch of modelling, however, is by far more common 
 now than it was in the time of Mr. Wedgwood j and good 
 workmen obtain fair remuneration for their labour. 
 
 The mould-maker receives the model, and forms from it 
 the requisite moulds, by employing plaster of Paris. 
 
 The gypsum or native sulphate of lime plaster is first 
 ground in a mill, similar to a flour-mill. It is then put in a 
 long trough, under which runs a flue communicating with the 
 fire, to effervesce until all the water is expelled. This process 
 is called both boiling and burning. The workman has his 
 mouth and nose always well covered, to prevent his inhaling 
 any of the dusty particles, which would, if taken inwardly, 
 be very prejudicial to the lungs. 
 
 The mould-maker forms, and secures by a broad strap, a 
 casing of thick clay round the model : he then mixes in a jug, 
 containing a certain quantity of water, the proper portion 
 of the soft impalpable powder or plaster, and stirring it 
 
466 
 
 TUB OPERATIVE MECHANIC 
 
 quickly, that the water may have an opportunity of pervading 
 it thoroughly, pours it upon and around the model : in some 
 instances gently or briskly shaking the mass. Some heat is 
 immediately given out, and the whole very soon becomes a 
 compact mass. After standing a short time, the mould is 
 easily separated from the model, and each part is placed in a 
 stove to be dried. 
 
 When the moulds are found to be perfect, they are kept 
 dry, by which they retain the property of absorbing moisture 
 with great rapidity, so that the squeezer can often separate 
 his work from them readily, and when this is the case, the 
 mould is said to deliver easily. 
 
 In some of the principal manufactories large slabs of 
 plaster are fitted up as shelves, which serve the twofold 
 purpose of holding the newly-formed articles, and of facilitat- 
 ing the drying, by absorbing a portion of the moisture. 
 
 The workman, called the dish-maker, who uses moulds, 
 for dishes, plates, saucers, w\ash-bowls, or hollow ware, 
 always cuts off from the mass a piece of clay according to the 
 size and strength of the article he has to make. This he 
 again cuts asunder, or breaks with his hands, repeating the 
 operation of forcibly slapping them together, to prevent any 
 air- bubbles from remaining in it. The piece is then laid on 
 a flat surface of board, or plaster, and the workman with a 
 heavy lump of clay, with a level under-surface, adapted for 
 holding in the hand, beats the clay to the thinness the vessel 
 is intended to form. These pieces of clay are technically 
 called hats. 
 
 For wash-bowls, dishes, or plates, the workman, called the 
 whirler, uses a vertical spindle, surmounted with a circular 
 block, ten inches diameter, and about two inches thick. On 
 this he places his plaster-mould, and with a bat lays the clay 
 properly upon it; he then with one hand gives motion to the 
 whole, while with the other, dipped in water, he presses the 
 clay very close to the plaster-mould : then, when any addi- 
 tional piece is required, as the ledge, or foot, it is joined on 
 with slip, and firmly squeezed to the other clay. Afterwards 
 a suitable thin tool or utensil of pot, of the profile of the 
 inside, is applied, to give the proper shape and thinness. 
 The sponge is now again employed to clean ofl* all excres- 
 cences ; the whole is cut to its size, finished with the sponge, 
 and set .to dry a little, and a horn tool is employed to trim 
 it off. 
 
 The moulds are capable of being used five or six times in 
 succession each day, because as soon as one has been charged 
 
and machinist. 407 
 
 jt is set in a stove lu dry, and as the workman proceeds 
 regularly, each is allowed equal time for drying. 
 
 When the bowls, dishes^ or plates, are taken off the 
 moulds, and have been pared round the edge with a thin 
 bladed knife, they are slightly polished by the hand, and 
 afterwards laid on each other in quantities of four, eight, 
 twelve, or more, according to their size and strength, to dry 
 and harden, preparatory to being placed in saggers for the 
 biscuit-oven. 
 
 The squeezer generally uses moulds which have two or 
 more parts. The moulds for figures have their parts numbered. 
 He takes a bat of a proper size and thickness, and lays it 
 in one part of the mould, then with a large sponge beats and 
 w'ell forces it into all the cavities ; he next takes another 
 part, on which is the bottom, and presses the two parts toge- 
 ther; he then rolls a piece of clay, and forces it into those 
 parts of the article where the mould joins together, and 
 afterwards cleans off all the excrescences, and secures the 
 parts by a leather strap, so that they cannot come asunder 
 while the mould is in the stove, or on the shelf, to dry to the 
 green state. When he takes the strap off, the parts of the 
 mould are carefully separated, and the vessel finished, by 
 the joints being pared, cleaned, and sponged. The spouts, 
 handles, covers, ornaments on the outside, and figures, are 
 similarly formed and finished off. 
 
 This part of the process was formerly performed by casting; 
 but casting is now only employed for the mos^ elegant 
 irregular shapes, where strength is not important. 
 
 The very dry mould is well closed together, and strapped 
 for security. Some clay is then mixed with pure water till 
 it be reduced to a pulp of the consistence of cream. This is 
 poured into the mould until it be filled, and the plaster, of 
 which the mould is formed, absorbs the water from the clay 
 that is contiguous to it, and leaves a coating of clay attached 
 to the mould. The pulp is then poured out, and the coating 
 allowed a short time to dry; a second charge of a much 
 thicker consistence is then poured in, and forms a body suffi- 
 ciently thick for the article intended, and when a coating is 
 again formed, the remainder of the pulp is poured off^ and 
 the mould placed a short time near a stove, and wlien suffi- 
 ciently dried is separated, and the article left to dry to the 
 green state : the seams of the joints are then smoothed off, and 
 -the article is finished by the skill of the workman, and when 
 thoroughly dried is placed in a sagger for the biscuit-oven. 
 
 All the articles made in the clav bv these various processes, 
 
 2ii2‘ ' 
 
THE OPERATIVE MECHANIC 
 
 4es 
 
 after being finished in reference to their shapes, figures, sizesy 
 ornaments, &c. are placed on boards, and left to dry by the 
 temperature of the apartment where they were made, or put 
 into a drying-house, green-house, or stove. 
 
 The sagger-maker^ is expected to know the exact propor- 
 tions of marl, old ground saggers, and sand, that are required 
 to form the best saggers for either pottery or porcelain. 
 Saggers are of different sizes, shapes, and depths, formed of 
 a very porous composition, and capable of bearing, without 
 being fused, a most intense heat. The bottom of each sagger 
 has a thin layer of fine white sand, to prevent the pieces of 
 pottery touching and adhering to it. 
 
 For porcelain flat ware, as plates, &c. the sagger is also 
 firmly filled with very dry flint, to preserve each piece in its 
 proper shape. When a sagger is filled with clay ware, on 
 its outer edges are placed thick pieces of coarse clay, called 
 wads from their being employed to wedge or closely join 
 the interstice between two saggers, as well as to support the 
 edges, and preserve equal pressure. 
 
 Each pile of saggers placed in an oven is called a hung; 
 and the man who places the ware in the saggers, and the 
 saggers in the oven, the oven-man. 
 
 The potter’s oven, for both biscuit and gloss firings, is very 
 much like that in which bricks and tiles are usually burnt in 
 most parts of the kingdom; that is, a cylindrical form, 
 surmounted by a dome. Around this oven are formed fire- 
 places or mouths, whence the fire passes into horizontal 
 flues in the bottom, and perpendicular flues, called bags, on 
 the inside, and so ascends through all the interstices of the 
 bungs of saggers, until the surplus escapes through the 
 aperture in the dome of the oven. 
 
 Most ovens are surrounded bj^ a high conical building, 
 called a hovel, large enough to allow the man to wheel coals 
 to the requisite places, and to pass along to supply each mouth 
 with fuel ; and at the same time to protect both him and the 
 oven from rain or any other atmospheric inclemency. 
 
 The saggers are sometimes placed to dry in the sides of the 
 hovel, and sometimes in a smoke house. 
 
 The biscuit-oven is always the largest upon the premises. 
 The workman is called the biscuit fireman, and is employed 
 from 48 to 50 hours at a time. The heat is gradually in- 
 
 *The word “ sagger ” is by many supposed to be a corruption of safe- 
 guard ; bu»t we are disposed to date its origin to the Hebrew, from the 
 word sagar, to burn. It is a baked earthen vessel into which others are 
 placed when put into the kiln. 
 
AND MACHINIST. 469 
 
 creased throughout the time, but porcelain does not require 
 it so long, as it more readily allows the heat to be raised. 
 
 In different parts of the oven, where they can be easily ex- 
 tracted, rings of Egyptian black clay are placed, as trials, by 
 which an experienced fireman can tell how much longer the 
 process must be carried on, not within an hour, as indi- 
 cated by Wedge wood’s pyrometer, but within ten minutes. 
 Hence the pottery district has a very pertinent proverb : 
 
 JVothing beats a trial,’* 
 
 The name of the ware thus fired is biscuit, because of its 
 being to appearance and feel like ship-bread when well baked; 
 the surface is devoid of any appearance except that of a 
 tobacco-pipe, sometimes tinged by the intense heat. When 
 the saggers are taken out, the articles are carefully sorted, 
 and all injured pieces are rejected. 
 
 If pottery were used in the biscuit state, it would, in some 
 cases, be permeable to water ; hence wine-coolers, alcazaras, 
 are always in the biscuit state. The best size of wine-coolers 
 is that which just admits the bottle, for then the air of the 
 room can very little affect the water in the cooler, which con- 
 sequently, bypassing from the inner to the outer surface, effects 
 the purpose sooner ; a humid coating being thus presented to 
 the action of the surrounding atmosphere, the evaporation 
 causes a consequent quicker diminution of heat than could 
 take place with a dry surface 
 
 All articles of pottery which have but one colour, and many 
 that have several, are in general ornamented either by the 
 pencil, or by impressions taken from copper-plates. The 
 former is called blue, or biscuit-painting, the latter blue- 
 printing, Both processes take place on the biscuit, prior to 
 the ware being dipped in the glaze, [f tlie ware were not 
 previously fired, and were capable of being handled about for 
 the painting, the water, used to soften the colours, would 
 soften the ware ; and the impressions from plates could not 
 be clearly, even if at all, transferred to the ware ; water also 
 could not be employed to wash off the paper, and the water 
 which contains the components of the glaze would be ab- 
 sorbed by the clay body, which would by this means be ren- 
 dered so soft as not to preserve its shape in the oven. 
 
 It has been thought that advantage might result from 
 being able to mix some substance with the clay of enamelled 
 ware, which would resist the action of water, as a suitable 
 glaze might then be first employed, and one firing answer for 
 both the biscuit and the gloss, which would save one operg^ 
 tion, as well as the time, labour, and expense of fuel, 
 
THE OPERATIVE MECHANIC 
 
 470 
 
 In blue- painting y the colour is mixed with water and gum, 
 and carefully laid on the biscuit ware. As every stroke leaves 
 a mark in the pores of the vessel, great attention must be 
 paid to the pattern, for a stroke once made can never 
 be rubbed out. After the pattern is finished, the ware i : 
 allowed to dry by the atmosphere, and is then dipped in th : 
 glaze ; it is afterwards exposed to heat in the gloss-oven 
 which fuses the minerals contained in the colours, and give4 
 to each a coating of true gloss : about 4000 young women are 
 employed in this branch of pottery, and by their industry 
 support themselves in a respectable manner. 
 
 Blue-printing is the impressions taken from engraved cop- 
 per-plates by means of a rolling-press. The bliie-printer lays 
 the plate upon a stove while the oily colouring substance is 
 rubbed in, and by the heat the metalline particles contained in 
 the oil flow and sink more readily into the engraved lines. 
 The colour is oxide of cobalt, fluxed with different sub- 
 stances, and in suitable proportions, for the pale or dark 
 blues. 
 
 The superfluous colour is carefully cleaned off the hot plate, 
 which is laid on the press, and covered wuth a piece of coarse 
 tissue paper, which has been first brushed over with a strong 
 lie of soft soap, called sizmg. The whole is now passed 
 through the press, and the heat of the plate dries the paper, 
 renders it more adhesive of colour, and also more easy to be 
 extracted from the plate. The impression when taken oft* the 
 plate is given to a girl, called a cutter^ who cuts it into 
 shapes, and hands the parts to a woman, (the transferrer,) who 
 puts them on the biscuit, and when she has properly arranged 
 them rubs them till the several pieces are completely affixed to 
 the biscuit article : the article is then left for a short time to 
 imbibe the colouring matter ; after which, the paper is well 
 washed off with clean water, and the article is put into a kiln 
 to dissipate the oil. Sometimes the outline of a pattern is 
 printed on the ware, and the colours are afterwards added 
 with a pencil. 
 
 The earthenware is now ready to receive the smooth coat- 
 ing called glaze or gloss. The employing of this glaze, 
 though in general, is not always, with a design to prevent the 
 vessel from imbibing the liquid that may, at any future time, 
 be poured into it ; because some bodies of earthenware are, 
 before glazed, impermeable to liquids of any kind ; but with 
 a design of accomplishing a more important object, that of 
 hiding the substance of the vessel, which is not always either 
 for fineness of texture or whiteness of colour, of a very pre- 
 
MACIHNiSfr. 
 
 471 
 
 possessing appearance. A coating of glaze would, by 
 
 its. transparency, only expose these defects ; even if it were 
 sqfiicieiitly contractile and expansile, by sudden changes of 
 temperature, to admit of its being used. Hence is employed 
 a^vitrifiable composition of oxides of lead, glass, tin, &c. some- 
 what resembling common flint glass, readily made fusible 
 by a little alkali and hardened flint, which will, when w ell 
 managed, possess sufihcient opacity, and by applying a certain 
 degree of heat, flow and vitrify, and render fusible any flint 
 or clay in contact with it, and thus not only fill up the 
 pores of the biscuit article, but cover the whole with an 
 opaque coating, that may be regarded as of real flint glass. 
 
 As the glaze that suits one, composition of ware will not 
 suit another, owing to the difference in kinds as well as pro- 
 portions of materials, it is ever requisite that the components 
 of the glaze be carefully appropriated to the hardness, density, 
 &c. of the components of the clay ; because a good glaze 
 should always possess the property of remaining, after being 
 fired, unaffected by heat or cold, in exactly the same ratio as 
 the clay', else on any sudden change of temperature, there 
 would be a counter action between the body and the glaze. 
 
 When the article is short-fired, it is always more susceptible 
 of the components of the glassy surface, and becomes al- 
 together crazed, or full of little cracks, which render it perme- 
 able to water, and receptive of oily and greasy, and other 
 heterogeneous substances, and ere long the article will, by 
 constant usage, appear very much like a rotten substance. 
 
 Crazing is the technical term for the cracking of the glaze, 
 whatever be the cause : whether it arise from excess of al- 
 kali in the materials composing the glaze, the deceptive 
 union of the body and glaze, the unsuitableness of the body 
 to the materials of the glaze, the components of the glaze not 
 being equally fusible at the heat employed, or the beat for the 
 proper fusion of the glaze being too high for the body 
 itself. 
 
 Mr. Parkes states, that a little lime mixed in the clay will 
 prevent crazing ; but manufacturers are of opinion that the 
 fact is the contrary. Lime will in a slight degree add to the 
 transparency of porcelain, but ever render it liable to craze. 
 If the articles, whether biscuit or gloss, be taken out of the 
 oven before tolerably cool, the temperature of the air will 
 most generally affect them, and especially the glaze, which is 
 not then properly annealed. 
 
 The glaze is a vitrifiable composition, about the consist- 
 ence of, and in appearance, very much like new cream. It is 
 
THE OPERATIVE MECHANIC 
 
 472 
 
 essential tiat it be thin, and when fired, possess a degree of 
 opacity to approach as nearly as possible to, and yet be below 
 the fusibility of the biscuit, that the combination may be 
 more intimate and permanent. Hence its composition varies 
 for each body, consonant with the view and experience of the 
 manufacturer ; and it is very seldom that it can be applied to 
 another body without previously altering its composition. 
 
 In some instances the cost of glazing is much less than in 
 others ; though economy is sought for in all, and each manu- 
 facturer regards his own as the best and cheapest of the kind 
 for the purpose to which it is employed. Great care is taken 
 that the recipes, which are considered very valuable, be kept 
 as much as possible secret among themselves, to prevent 
 foreign potters availing themselves of them, to the injury of 
 our manufacture. 
 
 Raw glazes are employed for the common pottery, such as 
 toys, jugs, tea- ware, &c. They are generally composed of 
 white-lead, Cornish-stone, and flint, ground by a hand-mill. 
 We have seen a few raw glazes for porcelain of a very good 
 quality ; but fritt glazes are mostly used, and are of excellent 
 quality. 
 
 Fritt is derived from a certain combination of different 
 materials being well mixed together, ov fritted, and then cal- 
 cined 3 which procures a union of all the parts, and a solidity 
 and purity not otherwise attainable. The fritt is generally 
 placed where it can be affected by a sufficient heat to fuse all 
 its ingredients, without volatilizing the uncombined alkali. 
 
 Lynn sand is occasionally one of the ingredients em- 
 ployed in the fritt. Some persons use soda, to render the 
 fritt more fluent while being fired. In some instances, com- 
 mon salt is used along with a portion of potash, which decom- 
 poses it, and drives off part of its impurity. The remaining 
 impurities are driven away in the process of fritting. Let it 
 be remembered, however, that brilliancy of glaze is formed 
 only by lead ', and that the employment of salts ever produces 
 a poor appearance. 
 
 The calcined fritt is pounded, picked, sifted, and ground to 
 an impalpable powder, after which it is mixed with certain 
 proportions of white-lead and flint, and again ground in a very 
 powerful mill. The finer it is ground, the more serviceable 
 it is for the purpose ; the glaze is every way better, is more 
 level on the ware, more readily and easily fired, of greater 
 brilliancy, and scarcely ever liable to craze. 
 
 The lead causes the other components to vitrify at a certain 
 iieat : and accordingly as more or less is used, the glazo 
 
AND MACHINIST. 
 
 473 
 
 Oecomes harder or softer. Many objections have been made 
 to its employment : those in reference to vessels for domes- 
 tic purposes we have already noticed j and in reference to the 
 dippers being subject to paralysis (which is supposed to 
 result from the lead,) every aid is afibrded by preventives, 
 and where attention is paid to personal cleanliness, and the 
 water and towel placed for their use are employed, deleterious 
 elfects can seldom be experienced. 
 
 The materials being w’ell-ground and in a state of fluidity, 
 are next put into the dipping tub. As the materials are heavy 
 it is requisite to keep the powder suspended, and uniformly 
 dispersed through the mass, which w^eighs about 32 oz. per 
 ale-pint. By the side of this tub stands the dipper, and a boy, 
 his assistant. The boy is employed in brushing the articles, 
 and delivering them, one by one, to the dipper, who dips them 
 quickly into the liquid, and as soon as he takes them out, 
 turns them rapidly about, that the thickness of the liquid 
 may be equal in all the parts. The water is imbibed by the 
 porosity of the biscuit, and there is left a coating of the sub- 
 stances, sufficiently hard to continue affixed until the article 
 be placed in the sagger. The article is then placed on a 
 board, another is similarly dipped, and thus it proceeds until 
 the quantity be finished, when the whole are put into saggers. 
 
 When a flat piece has been dipped, it is placed on a board, 
 in which are a number of nails, about an inch above the sur- 
 face ; the superfluous compound runs ofl^ the remainder 
 quickly dries, and soon admits of being moved ; which effects 
 a saving in fuel and materials, and the articles are better 
 glazed. 
 
 flollow pieces and blue-printed ware, are placed on hair 
 sieves, or on four pieces of sheet iron, from two to three feet 
 long, called a fiddle ; in three minutes the dipped articles 
 are sufficiently dry to be removed to the board, and a few 
 minutes afterwards to be placed in the saggers. 
 
 In the inferior earthenware certain metallic oxides, as of 
 copper. See. are mixed with the glaze. These kinds of glazes 
 are distinguished by the name of dips. When the article has 
 been thus dipped, it is finished on a turner’s lathe, to mark 
 what is to be white, and when the appendages are affixed it 
 is dried in the oven. 
 
 The articles are again put into the saggers to fuse the glaze, 
 and as in this process each would attach itself to the other, 
 were they to come in contact, pieces of clay of different sizes 
 and shapes, called stilts, cockspurs, rings, pins, bats, &c» 
 are put to keep them apart. 
 
THK OPERATIVB MECHANIC 
 
 4/4 
 
 The saggers are, as before, piled in the gloss-ovoi, which 
 seldom holds more than one half the quantity of ware fired in 
 the biscuit-oven. The gloss-Jireman raises the temperature 
 as quickly as possible to a height sufficient to fuse the glaze, 
 which is much lower than the heat of the biscuit-oven and 
 usually keeps it fired from 16 to 19 hours. Trials y made of 
 native red clay, are found very essential in this operation, to 
 prevent the ware being more intensely heated than the biscuit 
 body will bear ; for as clay contracts by every addition of heat, 
 were the heat of the gloss-oven to exceed the heat used 
 for the biscuit, the articles would be further contracted, and 
 would be either crooked in shape, or injured in the glaze. 
 The coating of glaze which adhered to the biscuit is, by this 
 firing, uniformly spread over the surface, the particles are 
 fused altogether, and the ware, when cold, appears to be 
 covered with perfect gloss. 
 
 As the gloss-oven is sometimes fired to a greater degree of 
 heat than some colours will bear, another process is employed, 
 called enamelUngy because the designs are more elegant in 
 their execution and form, and the colours are burnt into the 
 glaze of the pottery. These designs are of the finest descrip- 
 tion, and are most delicately executed upon the glossy surface. 
 
 The colours used are generally of a mineral or metallic 
 nature. For blacks^ oxide of umber and cobalt, and a little 
 oxide of copper. The best oxide of iron is produced by 
 causing heated air to act upon iron. 
 
 ¥ov purples and violets y precipitate of cassius, and oxide of 
 gold. 
 
 For greens^ oxide of copper, and precipitate of copper. 
 
 And for hluesy oxide of cobalt. 
 
 These oxides are all in an impalpable powder, and are mixed 
 with a certain powder as a flux, and are so prepared as never 
 to spread beyond their lines, or injure the drawing while 
 being fired. 
 
 Each colour is ground with a muller on a large hard stone, 
 and is incorporated with acid of tar, oil of turpentine, or 
 whatever oil may be deemed suitable, and is evaporative. 
 Camel-hair pencils are used to lay the colours on the pottery. 
 
 As both males and females are employed in this branch, the 
 men are c?\\Qd painters y the women paintresses : but in blue- 
 painting, where no men are employed, the women are called 
 blue-painters. 
 
 This is the finest and most durable species of painting, and 
 it is capable of being employed for the most elegant and valu • 
 able embellishments, as neither air, nor wear, can affect 
 
AND MACHINIST. 
 
 either the beauty of the design, or the brilliancy of the 
 colours. 
 
 Gilding requires the precipitate of gold from its solution 
 to be properly mixed with oil of turpentine, and great pains 
 must be taken in laying it on the pieces, which is done in a 
 manner similar to the preceding. When the article is heated, 
 the oxygen flies off and leaves on the ware the gold in a metal- 
 lic state ] but the natural brilliancy of the gold is wanting, 
 consequently, a burnisher of agate, blood-stone, or steel, is 
 applied to the gold, first moistened with flint-water, to pro- 
 cure the bright and shining property of the precious metal, 
 which is, by that means, quickly brought in view. This, when 
 the gold is not too much lowered by fluxing, will scarcely 
 ever tarnish. 
 
 Black-printing is a very distinct and curious process. The 
 tvorl^man boils a quantity of glue to a certain consistence, 
 and pours it on very smooth dishes, to the thickness of an 
 eighth or a quarter of an inch, according to the size of the 
 plate he may have to use. This, when cold, is cut into sizes 
 lor the plate, called papers ; and he makes as many as he can 
 conveniently use in his routine of working. 
 
 Then taking a copper-plate, properly engraved, he rubs 
 into it some well-boiled oil, and having properly cleansed the 
 plate, forcibly presses the glue-paper against it ; the latter 
 being firmly fastened to a piece of wood to be held in one 
 hand, and the paper being laid on a boss or cushion held in 
 the other. The oil in the plate adheres by the pressure to the 
 glue-paper, and he carefully, but firmly, presses it and the 
 piece of pottery together 5 then separates them, and with fine 
 cotton slightly sprinkles the colour (which is in an impalpable 
 powder) upon the design left by the oil. After a certain time 
 the oil has evaporated sufficiently to permit all superabundant 
 colour to be 'wiped off, which is done with much delicacy and 
 attention, by using old silk rags, and the black printed pot- 
 tery is placed in the enamel- kiln, where the glaze and colour 
 fuse and incorporate. 
 
 The enamel-kiln is commonly made in the shape of a 
 chemist’s muffle, from about six to ten feet long, and three to 
 five feet wide ; having from one to four mouths, according to 
 the size of the kiln, and the purposes to which it is applied ; 
 these mouths are made for the admission of fuel. In this kiln 
 the articles are verj^ carefully placed in layers, or thin bats, 
 until the whole be filled ; the mouth is then stopped, and the 
 kiln fired for about eight or ten hours. 
 
 The articles, when painted, gilded, or blitck printed, are 
 
476 THE OPERATIVE MECHANIC 
 
 subjected to a third firing in the enamel-kiln, which fuses both 
 the glaze and the colours, and the mineral or metallic particles 
 flow and become incorporated into the glassy surface. 
 
 Lustre ivare consists of an inferior quality of the materials 
 worked into the usual forms, and having the hue of gold, 
 platina, or copper, &c. fixed on the glaze, whose great 
 brilliance, when first made, occasioned it to be thus named. 
 
 The very easy method of performing the operation, and the 
 quick sale which the articles obtain, has caused it to become 
 so common, and of a quality so inferior, as to be little esteemed 
 by potters. 
 
 The pottery to receive lustre is made and glazed for the 
 purpose. That for gold lustre is made of the red clay of the 
 district, and when fired gloss, has just a sufficient tint left to 
 give to the articles that peculiar shade of colour observable on 
 viewing them. A very common article of cream-colour is 
 commonly used for the silver lustre. 
 
 The oxide used for lustre, as gold, platinum, &c. is mixed 
 with some essential oil by the application of heat, and the 
 fluid is brushed over the surface of the articles. Sometimes 
 ornaments are formed on the surface. For this purpose, a 
 thick fluid of soot or lamp-black is laid on the articles, by 
 brushes, according to the patterns, and the articles are then 
 heated in a veiy hot iron oven, and afterwards have the lustre 
 brushed over them. When dry, they are placed in a kiln, 
 similar to that for enamel ware ; which, being carefully fired, 
 dissipates the oxygen, loosens the ornamental article, and re- 
 stores the metallic lustre to a degree almost equal to its primi- 
 tive brilliance ; but in some cases it is of a coppery and 
 steely brilliance. 
 
 In Messrs. Rileys’ shining black biscuit porcelain, the ware 
 is of a jet black jasper, or porcelain body^ having undergone 
 a high degree of vitrification, which elicits a lustre, or bright 
 vitrified polish on the surface, of the appearance of black 
 coral, without a glaze, which is of considerable importance in 
 point of durability, elegance, and usefulness. It is warranted 
 never to change its elegant quality by time or use, and will 
 clean with water, equal to a piece of the finest porcelain. It 
 has a decided advantage over the dry body, or common 
 Egyptimi black, which is generally scoured and oiled to give 
 the surface a smooth appearance, by which it imbibes dust 
 and becomes offensive, and the substance of which it is com- 
 posed being of a porous nature, it becomes saturated with the 
 li(]uids poured into it, which eventually prove unwholesome, 
 as well as disagreeable to the hands and sight ) the whole of 
 
AND MACHINIST. 
 
 477 
 
 these disadvantages is obviated by Messrs. Rileys’ black 
 lustre, which, being perfectly vitrified, allows no liquid to be 
 imbibed. 
 
 The direful effects of using lead in the manufacture of pottery 
 are manifest by severe cholics, paratysis of the limbs, and 
 often the untimely death of the workmen ; and yet this dan- 
 gerous mineral forms the glaze of the common red pottery, in 
 which much of the food of the lower classes is prepared. 
 Lead is slightly soluble in animal oil, more copiously in the 
 acids of our common fruits, and more especially when their 
 action is aided by the heat required in cookery. It is not 
 improbable that many of the visceral disorders of the poor, 
 who use such potterj^, are attributable to this little suspected 
 source ; and that it is to procure the temporary removal of the 
 pain occasioned by the action of the lead, that they habituate 
 themselves to the deleterious use of distilled spirits. 
 
 It was on this view of the subject that the Society for the 
 Encouragement of Arts, Manufactures, and Commerce, were 
 induced to offer their largest honorary premium for the dis- 
 covery of a glaze for such red pottery, composed of materials 
 not any way prejudicial to the health, and which from its 
 cheapness, and fusibility at the comparatively low temperature 
 required by red pottery, might supersede the use of lead in 
 that branch of manufacture. 
 
 This important object was eventually discovered by 
 J. Meigh, Esq. of Shelton, who was well persuaded of the 
 possibility of its accomplishment, and who, without any 
 other stimulus than a desire to benefit mankind, first fully 
 ascertained what particular objects were contemplated by the 
 Society, and then communicated his successful process ; by 
 which any makers of red pottery, who may choose to depart 
 from long-established usage, which is but too often the 
 greatest obstacle to improvement, may easily remove the 
 source of the mischief, and considerably improve the quality 
 of the ware, and effect a saving in materials in fuel. 
 
 After this view of the subject, we shall not be required to 
 apologize for giving the process in Mr. Meigh’s own language. 
 
 The common coarse red pottery, being made of brick- 
 clay, is very porous, and is fired at as low a temperature as 
 possible, to save the expense of fuel, and to avoid fusion, or 
 variation of shape, which would result from highly firing 
 ' common clay ; consequently there is needed a glaze to fill up 
 the pores, that the vessel may contain fluids. This glaze 
 must be very fusible, and cheap ; hence, for transparent 
 vessels, litharge, and for black opaque, common lead ore, are 
 
THE OPERATIVE AIECHANIC 
 
 478 
 
 used. A glaze of lead, whether altogether or in part, is 
 objectionable, because, first, when quickly raised to the tem- 
 perature of boiling water, it cracks from different expansibility 
 of the clay and the glaze, so that the liquid permeates the 
 body of the vessel ; and secondly, the glass of lead, whether 
 alone or mixed with small proportions of earthy matter, is 
 very soluble in vinegar, in the acid juices of fruits, and in 
 animal fat when boiling.’' 
 
 The injurious effects arising from these have been already 
 stated. Mr. Meigh therefore proposes, that a mixture of red 
 marl, which can be easily ground in water to an impalpable 
 paste, and will remain suspended therein for a long time^ 
 be employed to dip the vessel in, so that its pores may be 
 filled with the fine particles of the marl, preparatory to 
 glazing; which is performed with a mixture, of the con- 
 sistence of cream, of equal parts of black manganese, glass, 
 and Cornish-stone, (chiefly felspar,) well ground and mixed 
 together ; in a white glaze the manganese is omitted. After 
 undergoing this process, the ware is well dried and fired, as 
 usual. 
 
 Mr. Meigh also proposes a substitute for the materials of 
 the common red pottery, consisting of four parts common 
 marl, one part red marl, and one part brick- clay. The ware 
 made in this way is of a reddish cream-brown, harder, more 
 compact, and less porous, than the red pottery ; more econo- 
 mic^ to the potter, and calculated to contribute in no incon- 
 siderable degree to the health of the lower classes who use 
 the red pottery. 
 
 The aim of the principal manufacturers has been to obtain 
 the composition of a clay and glaze for porcelain, which, 
 when fired, should be very fine in its tejcture, extremely white 
 in colour, possess considerable transparency, and at the same 
 time be able to bear different degrees of heat and cold. That 
 the reader may understand more fully the several peculiarities 
 which are considered by manufacturers as essential to perfect 
 porcelain, we shall state. 
 
 That the first and most important quality is a superiority 
 in the whiteness of the porcelain ; that its appearance be free 
 from any specks, and that it be covered with a rich and very 
 v'hite glaze of almost velvet softness in appearance, and of 
 best flint-glass smoothness to the touch. 
 
 That the second important and essential quality is dura- 
 hilitj/, or a substance whose components will bear, without 
 being injuriously affected, a sudden and rapid increase of 
 temperature, and particularly to sustain unaltei*ed, the action 
 of boiling water. 
 
and machinist. 
 
 479 
 
 T^at the third essential quality is transparency^ which is 
 "admitted to be, in some measure, requisite, but certainly not 
 entitled to that high degree of preference so frequently given 
 to it, the best porcelain being a shade less transparent than 
 n kind much inferior. 
 
 Formerly, connoisseurs very highly estimated porcelain 
 of a fine granular texture ; but this criterion of excellence 
 cannot always be relied on. 
 
 To ascertain the texture of an article, it must be fractured, 
 and thereby tacitly destroyed ; the semi-vitrification and 
 closeness of texture observable in one piece will not be so 
 obvious, but there will be a varied appearance in different 
 pieces, though all be fabricated at the same time, and from 
 the same mass of materials. 
 
 Stone-china is formed of a compound of Cornish-stone and 
 clay, blue clay, and flint ; and with a glaze, consisting of lead, 
 bullet-glass, Cornish-stone, and flint. It is very dense and 
 durable, but less transparent than bone-china ; and is very 
 much used for jugs, and the larger sorts of vessels. 
 
 Iron-stone china is not very transparent ; but possesses 
 great strength, compactness, density, and durability. It is 
 not much used for tea- ware, but has very suitable properties 
 for dinner and supper services, jugs, and ornaments. It was 
 discovered by Messrs. G. and C. Mason, and has been 
 more productive than any other species of pottery or 
 porcelain. 
 
 Felspar china, which has been only very recently intro- 
 duced, is the most noted of all the porcelains ; it results from 
 the introduction of certain proportions of a fresh material into 
 both the clay and glaze. 
 
 Cornish-stone is a species of granite in a state of decom- 
 position, and contains much felspar. Cornish-clay is found 
 in situations where this decomposition is in progress. The 
 decomposing granite is broken up with pickaxes, and the 
 fragments are thrown into running water, whose action washes 
 off, and keeps in suspension, the slight argillaceous particles 
 miscible with that fluid. The water is discharged into pans 
 or pits, where the particles subside, and the water is evapo- 
 rated, formerly by the atmosphere, but now by heated flues 
 passing under the reservoirs. When the water is evaporated, 
 the substance is cut out in square lumps, and placed on shelves 
 to dry, when it becomes extremely white, and in the state of 
 an impalpable powder. It is then packed up in casks, and 
 forwarded to the manufacturers. 
 
 The clay of the best felspar porcelain is formed of certain 
 
480 
 
 THE OPERATIVE MECHANIC 
 
 proportions of china- stone and felspar ; the mixing of th^ 
 proportions requires much attention, for an excess of felspar 
 would cause the vessels to shrink in the biscuit-oven, prior 
 to the fusion of the clayey particles, which causes its trans- 
 parency; and an excess of china-clay would increase the 
 opaqueness. In both cases, the glaze would expand and con- 
 tract in a ratio differing from that of the biscuit, and cause 
 the pieces to be crazed. The fusibility of native felspar is 
 owing to its containing about 13 per cent, of potash, which 
 causes it to be one of the best materials for glazing porcelain. 
 Calcined bone is used, and renders the clay very white ; but 
 it should be employed with judgment, as its great con- 
 tractibility causes the articles wherein it is used to excess, to 
 crack on sudden changes of temperature. 
 
 Beside the porcelain or china-clay already noticed, the 
 manufactures use four other kinds ; the two first from Devon- 
 shire, the two last from Dorsetshire. 
 
 The black clay is remarkable for the fact, that the bituminous matter 
 which gives the colour whence it derives its name, flies off by firing ; and 
 the blacker the clay when first dug, the whiter will be the pottery. 
 
 The cracking clay is used because of its extremely beautiful whiteness 
 when fired ; but it requires very exact proportions of flint, otherwise the 
 ware will crack during the firing of the biscuit. 
 
 The brown clay burns very white without cracking, and some manufac- 
 turers use much of it ; but as the ware does not so readily imbibe the 
 particles of melting glaze, the liability of the ware to craze causes others to 
 reject it altogether. This clay is with difficulty sifted through the lawn, re- 
 quires much longer weathering, or exposure to the action of the atmosphere, 
 for the separation of its particles, and to prevent crazing, different propor- 
 tions of other materials ; but the greatest objection to it is, that some of the 
 kind sent within these few years has always burned inferior in colour to what 
 it formerly did. 
 
 The blue clay is the best, and the most expensive. It forms a very 
 white and solid body, and requires a much greater proportion of flint, which 
 considerably improves the quality of the ware ; but the proportions require 
 very strict attention, and a higher degree of biscruit-fire. 
 
 The cream-coloured i^ottery has its name from the tint of 
 its colour being that of new cream. It is, when well made, 
 and properly fired, very sonorous, sufficiently hard to elicit 
 sparks by the application of steel, and vrill contain liquids 
 without being permeated by them. When it is of good quality, 
 it will resist the action of nitre, glass of lead, and other fluxes, 
 which renders it of great utility in all domestic and chemical 
 processes where great heat is used. Care must be paid to 
 the current of air while the pottery is in contact with fire, 
 otherwise its hardness and density, by preventing its sudden 
 contraction or expansion, renders it very lialile to break. 
 
 Wedgwood’s cream-coloured pottery is allowed to retain 
 
AND MACHINIST. 
 
 481 
 
 its superiority, neither failing nor crazing through age ; while 
 much of the pottery made by persons of small capital is very 
 subject to both these defects. 
 
 Cream colour is formed, according to the views of the 
 manufacturers 3 of various proportions of blue and porcelain 
 clays, flint, and Cornish-stone; others add black, or brown, 
 and cracking clays, with little flint and stone. Recent expe- 
 riments prove that pottery of very good quality may be made 
 by mixing from 30 to 40 per cent, of the native clay with 
 bine and porcelain clays, and flint and stone. 
 
 The glaze for cream-coloured pottery is formed of white 
 lead. Cornish-stone, and flint. The excess of lead renders 
 the glaze more or less yellow, which is remedied by the 
 application of other materials ; the flint gives consistence to 
 the lead during vitrification, and prevents its great fluidity, 
 wliich else would cause it to run down the sides of the ware, 
 and leave certain parts without glaze. 
 
 The deleterious effects arising from the employ of white 
 lead in the fabrication of vessels used for condiments have 
 been pointed out, as has also the importance of a substitute ; 
 but as the best manufacturers use much Cornish- stone and 
 flint in their glaze, and more especially for those vessels called 
 bakers, the cause of complaint does not attach itself to their 
 pottery. All persons, therefore, who wash their pickles and 
 preserves to be unaffected by this poisonous mineral, should 
 resolve on purchasing their jars from the dealers who have 
 their goods from the most respectable manufacturers, who 
 will readily vouch for the excellence of their articles. 
 
 It is not sufficiently known, that most of the earthenware 
 sold by hawkers, or pedlars, is of a very inferior and dangerous 
 quality. The components of the clay of which this common 
 earthenware is made, will not bear a fair degree of heat, and 
 in addition to the w'are being short-fired in the biscuit, the 
 glaze is too soft and short-fired; hence, when such earthenware 
 has been used a few times, the hot ^vater requisite for cleans- 
 ing it will cause all its defects to be obvious, and ere long it 
 becomes so crazed as to resemble a rotten substance. 
 
 This soft and *soft-glazed pottery is easily scratched by a 
 knife ; oily matters standing on it will stain and render it 
 dull ; and vinegar, and other weak acids, will attack and dis • 
 solve the lead. 
 
 The proper cream colour will bear all of these uninjured, 
 and so small a quantity of lead is used, that, when properly 
 glazed, pernicious effects need not be apprehended* 
 
 It is the opinion of some very intelligent potters, that the? 
 
 2 i' 
 
482 
 
 THE OPERATIVE MECHANIC 
 
 total rejection of lead is not compatible with perfection in 
 pottery. 
 
 The blue-printed pottery is a very popular kind, and most 
 persons who have seen it placed near the preceding, must 
 have remarked that it is of a finer kind, with a very different 
 tint or colour. 
 
 The best species is in considerable demand for dinner, 
 dessert, tea, and supper services 3 while its cheapness has 
 caused it to supersede almost every kind of ware. 
 
 The difference is caused by two peculiarities ; one in the 
 clay, arising from the employment of a greater proportion of 
 blue and porcelain clays and flints ; the other in the glaze, 
 from certain components being mixed together, and calcined 
 into a frit, which is often picked and sifted, then ground 
 together with glass and white lead, and mixed with certain 
 proportions of Cornish-stone and flint. 
 
 One kind of this pottery has its glaze varied to capacitate 
 it for enamelling. The blue printed tea-w^are has recently 
 obtained the name of semi-china^ owing to its being, when wxll 
 fired, very fine, white and neat, and possessing some degree 
 of traiisparency. 
 
 The chalky pottery is a very excellent and beautiful kind, 
 having a delicate white appearance, of fine texture, and glassy 
 smoothness. The nature of the ciay and the glaze renders it 
 very proper for enamelling, as smalts are introduced, in ac- 
 cordance with the views of the maker, to effect the tints. 
 
 The'clay is boiled on a plaster-kiln, and consists of certain 
 proportions of porcelain, blue and Welsh clays, pulverized, 
 calcined, or raw flints, Cornish-stone, white enamel, tinged 
 with smalts ; and some persons add calcined bone and plaster 
 of Paris. This ware requires a most ardent fire for the biscuit. 
 
 The glaze is composed of a frit of glass, Cornish-stone, 
 flint, borax, nitre, red-lead, potash, Lynn sand, soda, and 
 cobalt calx. After fritting, and being well fired, it is ground 
 and mixed together wdth white-lead, glass, flint, and Cornish- 
 stone. 
 
 fine red pottery is formed of almost equal proportions 
 of yellow brick-clay and the red from Bradwall-wood ; an 
 inferior sort is made for lustre-ware. 
 
 In the Hall-field colliery, east side of Henley, is found a 
 marl, which, wdien properly prepared, by levigating and drying, 
 will alone form a very beautiful light red, of four distinct 
 shades, according to the intensity of the firing. This was 
 discovered by Mr. G. Jones, in 1814, who commenced a manu- 
 facture of this kind of ornamental pottery for Messrs. Burnett, 
 
AND MACHINIST, 
 
 483 
 
 to be shipped to Holland : but the sudden return of Napoleon 
 from Elba so disconcerted the arrangements^ that the elder 
 Mr. Burnett died suddenly, and Jones did not long survive 
 the disappointment he experienced. 
 
 The introduction of ochre will change the red to a brown 
 colour. 
 
 The bamboo, or cane-coloured pottery, is a very beautiful 
 kind, employed chiefly for ornamental articles, and the larger 
 vessels of tea-services. It is never glazed outside, though 
 one kind has the outside vitrified. The insides of tea-ware 
 are well washed with a liquid which forms, when fired, a thin 
 coating of glass. The colour varies from that of a light 
 bamboo to almost a buff : but the prevalent colour is nankeen. 
 The best clay or body is formed of proportions of black marl, 
 brown clay, Cornish-stone, and shavings of cream-coloured 
 potteryi 
 
 The jasper pottery was invented by Mr. J. Wedgwood. It 
 is extremely beautiful ; and is formed of blue and porcelain 
 clay, Cornish-stone, Cork- stone, (sulphate of barytes,) flint, 
 and a little gypsum, tinged with cobalt calx. 
 
 The pottery is a superb kind for elegant and tasteful 
 ornaments, and is so much valued, that the workmen are 
 usually locked up, and employed only on choice articles. The 
 components of the clay are blue and porcelain clay, Cornish- 
 stone, a little glass, and red-lead. This forms the best body 
 for apothecaries’ mortars ; but it is more expensive, and more 
 durable, than the common mortar body. 
 
 The black F^gyptian pottery is now so very popular for 
 tea-services, that few persons are ignorant of what is meant 
 by this denomination. Its components are cream-coloured slip, 
 manganese, and ochre ; sometimes glazed with, lead, Cornish- 
 stone, and flint ; and the inside is washed with white-lead, 
 flint, and manganese. It w'as the custom formerly to grease 
 the outside with butter or suet, to give it a bright appearance. 
 
 The ochreous material is obtained from the water that is 
 pumped out of the collieries. This water is carried along 
 channels in which are placed small weirs, to afford an oppor- 
 tunity for the precipitation of the sediment. When a sufficient 
 quantity has accumulated, the w^ater is diverted, the weirs 
 are emptied, and the thick fluid is thrown into small pools, 
 called sun-pans, whence the moisture is evaporated by the 
 solar heat. This substance is afterwards burned with small- 
 coal, which renders it proper for use. 
 
 The unpleasantness of the grease, requisite to give bright- 
 ness to the black, having been a subject of general complaint, 
 
 2 I 2 
 
484 
 
 THU OPERATIVE MECHANIC 
 
 Messrs. Rilc\^j of Burslem, were induced to attempt to remedy^ 
 it ; the result of which was, the invention of a new black 
 porcelain, with a bright burnished, vitrescent appearance, 
 superior to any other kind of dry-body pottery. It never 
 imbibes dust, or absorbs moisture; and it can be cleaned with 
 water equally as well as the finest porcelain, and always retains 
 the appearance of a beautiful black coral. 
 
 The drah pottery is useful for articles which require strength 
 to be united to ornament, as fiower-pots, water-jugs, &c. 
 It is formed of blue, porcelain, and Bradwall-wood clays, 
 Cornish- stone, and black marl, mixed with nickel ; one kind 
 is made of turners’ shavings of cream-coloured ware made 
 into slip, and mixed with nickel. The inside is rendered 
 white by a wash of slip, flint, and porcelain clay. 
 
 It has for some time been usual for ladies of taste and 
 acquirements in the fine arts, to purchase porcelain in its^ 
 glazed state, for the exercise of their talents and ingenuity 
 in ornamenting their own tea-services. This very pleasing 
 amusement is often aided by manufacturers, who readily 
 afford every assistance in their power to facilitate the easy 
 enamelling of such services ; they supply proper mineral 
 colours, and the rectified oil of amber, for the best purposes, 
 and the best oil of turpentine for others ; and they attend to 
 the proper firing of the enamel, burnish the gold, and dress 
 off the whole for the table. 
 
 Tlie different combinations of materials appear to be of 
 less importance in the fabrication of good pottery, than due 
 regard to weli-determined proportions. All clays have some 
 proportions, more or less, of metallic matter, which cause 
 great difference in their appearance, and the effects produced 
 on them by fire. All clays vary in colouring according 
 to the ardency of the fire ; hence the oven-man’s greatest care 
 is, to place the saggars in the most appropriate parts. 
 
 Iffie chief ingredients are clay and flint ; for no pottery 
 will be perfect unless made of suitable clay, with a definite 
 proportion of flint. The great difficulty is to unite beauty 
 and goodness in the same composition. If too much flint be 
 used, the pottery, after being fired, wffll crack on exposure to 
 the air ; and if too little, the glaze will not be retained on it 
 after firing. Every kind of clay that is dried alone will crack; 
 for if pure argillaceous earth be made sufficiently soft to be 
 w’rought on the potter’s wheel, it will, while drying, shrink 
 one inch in tw^elve, which will inevitably cause it to craze. 
 
 Pure clay (alumina) is always opaque, and the flint (silica) 
 always transparent ; but both are prepared previously to 
 
AND MACHINIST. 
 
 485 
 
 being used. Alumina will unite with silica in the humid 
 way, and form a paste, which, when dry, will resist decom- 
 position by atmospheric affection. 
 
 Experienced manufacturers know that they can easily 
 compound clays which will fire very white, be beautifully 
 semi-transparent for porcelain, and bear to be covered with a 
 shining glaze ; but they will prove deficient in tenacity for 
 working, want proper compactness and density, break by 
 sudden applications of heat and cold, and the glaze, because 
 too soft, will crack, become rough, and lose its lustre. Again, 
 they compound clays which have suitable tenacity for working, 
 become very hard and dense without fusing by being fired, 
 sustain, uninjured, sudden changes of excess of temperature, 
 and are yet deficient in the requisite whiteness, fineness of 
 texture, beauty, and transparency. Some clays of this descrip- 
 tion are manufactured. 
 
 Having proceeded thus far, the reader may feel surprised 
 that we have not accompanied our observations with recipes 
 for the manufacture of the several kinds of pottery, as is cus- 
 tomary in works of this description ; but these, w^e can assure 
 him, are, as far as we have seen, erroneous ; and, indeed, the 
 manufacturers are so very silent upon this head, that the 
 exact proportions of the components of bodies, glazes, and 
 colours, cannot easily be obtained. We shall therefore con- 
 clude this article by stating, that the district called the 
 Potteries,” is an extensive tract of comitry in the hundred 
 of North Pyrehill and county of Stafford, comprehending an 
 area of about eight miles long, and six broad ; and that the 
 principal towns and hamlets contained wdthin the limits of 
 the Pottery are Stoke, Henley, Shelton, Golden-hill, New- 
 field. Smith-field, Tunstall, Long-port, Burslem, Cobridge, 
 Etruria, Lune-End, Lower Lune, and Lune- Delft. 
 
486 
 
 THE OPERATIVE MECHANIC 
 
 HOROLOGY 
 
 In the early ages, time was measured either by the sun- 
 jdial or clepsydra ; in the former, by the shadow of a wire, or 
 of the upper edge of a plane, erected perpendicularly on the 
 dial, falling upon certain lines meant to indicate the hour ; in 
 the latter, by the escape of water from a vessel through a 
 small orifice, which vessel had certain marks upon it to 
 show the time the vessel was discharging. 
 
 These modes are now superseded by the use of clocks, 
 watches, and chronometers, which indicate time by the move- 
 ment of machinery. 
 
 Under this general head of Horology, therefore, we propose 
 to treat of the structure of the several kinds of machines now 
 used for the exact measurement of time ; in doing which, the 
 article will of necessity be divided into three sub-heads. 
 Clocks, Watches, and Chronometers ; and to them will be 
 annexed two others, treating of some of the best kinds of 
 pendulums and escapements. 
 
 CLOCKS. 
 
 Clocks are certain machines, constructed in such a manner, 
 and so regulated by the uniform action of a pendulum, as to 
 measure time, in larger or smaller portions, with great exact- 
 ness 
 
 Fig. 489 represents the profile of a clock. P is a weight suspended by a 
 rope that winds about the cylinder or barrel C, which is fixed upon the axis 
 a a; the pivots b b go into holes made in the plates TS, T S, in wliich they 
 turn freely. These plates are made of brass or iron, and are connected by 
 means of four pillars Z Z, and the whole together is called the frame. 
 
 The weight P, if not restrained, would necessarily turn the barrel C with 
 an uniformly accelerated motion, in the same manner as if the weight were 
 falling freely from a height ; but the barrel is furnished with a ratchet-wheel 
 K K, the right sides of whose teeth strike against the click, which is fixed 
 with a screw to the wheel D D, as represented in fig. 490, so that the action 
 of the weight is communicated to the wheel D D, the teeth of which act 
 upon the teeth of the small wheel d, which turns upon the pivots c c. The 
 communication or action of one wheel with another is called the pitching ; 
 a small wheel like d is called a pinion^ and its teeth the leaves of the pinion. 
 Several things are requisite to form a good pitching, the advantages of which 
 are obvious in all machinery where teeth and pinions are employed. The. 
 teeth and pinion-leaves should be of a proper shape, and perfectly equal 
 among themselves ; the size also of the pinion should be of a just proportion 
 to the wheel acting upon it ; and its place must be at a certain distance 
 from the wheel, beyond or within which it will make a bad pitching. 
 
 The wheel E E is fixed upon the axis of the pinion d ; and the motion 
 communicated to the wheel D D by the weight is transmitted to the pinion 
 
ft StoMey sc 3St StrsAd 
 
AND MACHINIST. 
 
 487 
 
 d, coi^equently to ttie whesl E E, as likewise to the pinion e, and wheel 
 FF which moves the pinion/, upon the axis of which the crown or balance 
 wheel G H is fixed. The pivots of the pinion / play in holes of the plates 
 L M, which are fixed horizontally to the plates T S. In short, the motion 
 begun by the w'eight is transmitted from the wheel G II to the pallets I K, 
 vUnd by means of the fork UX, rivetted on the pallets, communicates motion 
 to the pendulum A B, which is suspended upon the hook A. The pendulum 
 A B describes, round the point A, an arc of a circle, alternately going and 
 returning ; if, therefore, the pendulum be once put in motion by a push of 
 the hand, the weight at B will make it return upon itself, and it will continue 
 to go alternately backward and forv/ard till the resistance of the air upon 
 the pendulum, and the friction at the point of suspension at A, destroys the 
 originally impressed force. But as, at every vibration of the pendulum, tlie 
 teeth of the balance-wlieel G H act so upon the pallets I K, (the pivots upon 
 the axis of these pallets play in two holes of the potence s t,) that after one 
 tooth, H, has communicated motion to the pallet K, that tooth escapes, 
 then the opposite tooth, G, acts upon the pallet I, and escapes in the same 
 manner ; and thus each tooth of the wheel escapes the pallets I K, after 
 having communicated their motion to the pallets in such a manner that the 
 pendulum, instead of being stopped, continues to move. 
 
 The wheel E E revolves in an hour. The pivot c of the wheel passes 
 through the plates, and is continued to r ; upon the pivot is a wheel N N, 
 with a long socket fastened in the centre ; upon the extremity of this socket, 
 r, the minute-hand is fixed. The wheel N N acts upon the w^heel O, tlie 
 pinion, p, of which acts upon the wheel g g, fixed upon a socket which 
 turns along with the wheel R. The wheel gg makes its revolutions in 
 twelve hours, upon the socket of which the hour-hand is fixed. 
 
 From the foregoing description it is evident^ first, that the 
 weight P turns all the wheels, and at the same time continues 
 the motion of the pendulum ; secondly, that the quickness of 
 the motion of the wheels is determined by that of the pen- 
 dulum ; and thirdly, that the wheels point out the parts of time 
 divided by the uniform motion of the pendulum. 
 
 When the cord from which the weight is suspended is 
 entirely run down from off the barrel, it is wound up again ];y 
 means of a key, which goes on the square end of the arbor 
 at Q, by turning it in a contrary direction from that in which 
 the weight descends. For this purpose, the inclined side of the 
 teeth of the wheel II, fig. 490, removes the click C, so that 
 the ratchet-wheel, K, turns while the wheel D is at rest ; but 
 as soon as the cord is wound up, the click falls in between 
 the teeth of the wheel D, and the right side of the teeth 
 again act upon the end of the click, which obliges the wheel 
 T> to turn along with the barrel, and the spring A keeps the 
 click between the teeth of the ratchet-wheel R. 
 
 We shall now explain how time is measured by the pen- 
 dulum ; and how the wheel E, upon the axis of which the 
 minute-hand is fixed, makes but one precise revolution in an 
 hour. The vibrations of a pendulum are performed in a 
 shorter or longer time in proportion to the length of the pen- 
 
488 
 
 THE OPERATIVE MECHANIC 
 
 dulum itself. A pendulum of 3 feet French lines in length 
 makes 3,600 vibrations in an hour, that is, each vibration is 
 performed in a second of time, and for that reason it is called 
 R seco7uls pendulum ; but a pendulum of 9 inches 2\ French 
 lines makes 7j200 vibrations in an hour, or two vibrations in 
 a second of time, and is called a half-second pendulum. 
 Hence, in constructing a wheel whose revolution must be 
 performed in a given time, the time of the vibrations of 
 the pendulum, which regulates its motion, must be consi- 
 dered. Supposing, then, that the pendulum A B makes 
 7^200 vibrations in an hour, let us consider how the wheel E 
 shall take up an hour in making one revolution. This entirely 
 depends on the number of teeth in the wheels and pinions. 
 If the balance-wheel consists of SO teeth, it will turn once in 
 the time that the pendulum makes 60 vibrations ; for at every 
 turn of the wheel, the same tooth acts once on the pallet I, 
 and once on the pallet K, which occasions two separate 
 vibrations in the pendulum ; and the wheel having 30 teeth, 
 it occasions twice 30 or 60 vibrations. Consequently, this 
 wheel must perforin 120 revolutions in an hour, because 60 
 vibrations, which it occasions at every revolution, are con- 
 tained 120 times in 7/200, the number of vibrations performed 
 by the pendulum in an hour. 
 
 In order to determine the number of teeth for the wheels E F, and 
 the pinions e/, it must be remarked, that one revolution of the wheel E 
 must turn the pinion e as many times as the number of teeth in the pinions 
 is contained in the number of teeth in the wheel. Thus, if the wheel E 
 contains 72 teeth, and the pinion e six, the pinion Vv'ill make 12 revolutions 
 in the time that the wheel makes one ; for each tooth of the wheel drives 
 forward a tooth of the pinion, and when the six teeth of the pinion are 
 moved, a complete revolution is performed; but the wheel E has by that 
 time only advanced six teeth, and has still 66 to advance before its revolu- 
 tion be completed, which will occasion 11 more revolutions of the pinion. 
 For the same reason, the wheel F having 60 teeth, and the pinion/ six, the 
 pinion will make 10 revolutions while the wheel performs one. Now the 
 wheel F, being turned by the pinion <?, makes 12 revolutions for one of the 
 wheel E; and the pinion / makes 10 revolutions for one of tlie wheel F ; 
 consequently the pinion / performs 10 times 12, or 120 revolutions in the 
 time the wheel E performs one. But the wheel G, which is turned by the 
 pinion/, occasions 60 vibrations in the pendulum each time it turns round; 
 consequently, the wheel G occasions 60 times 120, or 7,200 vibrations of 
 the pendulum, w'hile the w'heel performs one revolution ; but 7,200 is the 
 number of vil)rat!ons made by the pendulum in an hour, and consequently 
 the wheel E performs but one revolution in an hour ; and so of the rest. 
 
 From this reasoning, it is easy to discover how long a clock 
 may be made to go for any length of time v/ithoiit winding 
 i)p : 1 . by increasing the number of teeth in the wheels ; 
 2 . by diminishing the number of teeth in the pinions ; 3. by 
 increasing the length of cord that suspends the weight ; 
 
f 
 
 t’lvO'TlKS 
 
 From t90 to 
 
 ifetU it StoekU^ sc ^Sz Simnd 
 
ij 
 
 
 
 
 
 
 r • ■ , ■■ 
 
AND MACHINIST. 
 
 489 
 
 4, by increasing' the length of the pendulum ; and 5. by 
 adding to the number of the wheels and pinions. But^ in 
 proportion as the time is augmented, if the weiglit continues 
 the same, the force which it communicates to the last wheel, 
 G H, will be diminished. 
 
 It only now remains for us to take notice of the number of 
 teeth in the wheels which turn the hour and minute hands. 
 The wheel E performs one revolution in an hour ; the wheel 
 NN, which is turned by the axis of the wheel E, must like- 
 wise make only one revolution in the same time ; and the 
 minute-hand is fixed to the socket of this wheel. The wheel 
 N has 30 teeth, and acts upon the wheel O, which has like- 
 wise 30 teeth, and the same diameter; consequently the 
 wheel O takes one hour to a revolution. Now the wheel Q 
 carries the pinion />, which has six teeth, and which acts upon 
 the wdieel gg, of teeth ; consequently the pinion p makes 
 12 revolutions while the wheel gg makes one, and of course 
 thew’heel^'^ takes 12 hours to one revolution; and upon 
 the socket of this wheel the hour-hand is fixed. Ail that has 
 been here stated concerning revolutions is equally applicable 
 to watches as to clocks. 
 
 Clock-work, properly so called, is that part of the move- 
 ment which strikes the hours, &c. on a bell ; in contradis- 
 tinction to that part of the movement of a clock or ^vatch 
 which is designed to measure and exhibit the time on a dial- 
 plate, and v/hich is termed watch-work. 
 
 Fig. 491 represents the clock part. II is the first or great wheel, moved 
 by means of the weight or spring at the barrel G. In 16 or 34 hour clocks, 
 this wheel has usually pins, and is called the piii-ivheel; and in eight-day 
 pieces, the second wheel, I, is commonly the pin-wheel, or striking-wheel, 
 and is moved by the former. Next the striking-wheel is the detent-wheel, 
 or hoop-wheel, K, having a hoop almost round it, wherein is a vacancy at 
 which the clock locks. The next is the third or fourth wheel, according to 
 its distance from the first, called the tvarning-wheel, L. TJie last is the 
 flying-pinion, Q, with a fly or fan, to gather air, and so bridle the rapidity 
 of the clock’s motion. To these must be added the pinion of report, which 
 drives round the locking-wheel, called also the count-ivheel, which has, in 
 general, eleven notches, placed at unequal distances, to make the clock 
 strike the hours. 
 
 Besides the wheels, to the clock part belongs the rash or ratch, which is a 
 kind of wheel with twelve large fangs, running concentrical to the dial-wheel, 
 and serving to lift up the detents every hour, and make the clock strike ; 
 the detents, or stops, which being lifted up and let fall, lock and unlock the 
 clock in striking ; the hammer, as S, which strikes the bell R ; the hammer- 
 tails, as T, by which the striking-pins draw back the hammers ; latches, 
 whereby the work is lifted up and unlocked ; and lifting-pieces, as P, which 
 lift up and unlock the detents. 
 
 We shall now proceed to give a description of an ingenious 
 
490 
 
 THE OPERATIVE MECHANIC 
 
 clock, contrived by the late Dr. Franklin, of Philadelpina, 
 that showed the hours, minutes, and seconds, with only three 
 wheels and two pinions in the whole movement. 
 
 The dial-plate of this clock is represented by fig. 492. The hours 
 are engraved in spiral places, along two diameters of a circle, containing 
 four times 60 minutes. The index A goes round in four hours, and counts 
 the minutes from any hour it has passed by to the next following hours. 
 The time as appears in the figure is either 32§ minutes past 12, or past 4, 
 or past 8 ; and so on in each quarter of the circle, pointing to the number of 
 minutes after the hours the index last left in its motion. Now, as one 
 can hardly be four hours mistaken in estimating the time, he can always 
 tell the true hour and minute by looking at the clock, from the time he 
 rises till the time he goes to bed. The small hand B, in the arch at top, goes 
 round once in a minute, and shows the seconds as in a common clock. 
 
 Fig. 493 shows the wheel-work of the clock. A is the first or great 
 wheel; it contains 160 teeth, goes round in four hours, and the index A 
 (fig. 492) is put upon its axis, and moved round in the same time. The 
 hole in the index is round ; it is put tight upon the round end of the axis, 
 so as to be carried by the motion of the wheel, but may be set at any time 
 to the proper hour and minute, without affecting either the wheel or its axis. 
 This wheel of 160 teeth turns a pinion, B, of ten leaves ; and as 10 is but 
 a sixteenth part of 160, the pinion goes round in a quarter of an hour. On 
 the axis of this pinion is the wheel C of 120 teeth ; it also goes round in a 
 quarter of an hour, and turns a pinion D, of eight leaves, round in a 
 minute ; for there are 15 minutes in a quarter of an hour, and 8 times 
 15 is 120. On the axis of this pinion is the second-hand B, (fig. 492, and 
 also the common wheel E, fig. 493, of 30 teeth, for moving a pendulum (by 
 pallets) that vibrates seconds, as in a common clock. 
 
 This clock is not designed to be wound up by a winch, 
 but to be drawn up like a clock that goes only thirty hours. 
 For this purpose, the line must go over a pulley on the axis 
 of the great wheel, as in a common thirty-hour clock. 
 
 One inconvenience attending this clock is, that if a person 
 wake in the night, and look at the clock, he may possibly be 
 mistaken in the four hours, in reckoning the time by it, as 
 the hand cannot be upon any hour, or pass by any hour, 
 without being upon, or passing by, four hours at the same 
 time. In order, therefore, to avoid this inconvenience, tlie 
 ingenious Mr. Ferguson contrived the following method. 
 
 In fig. 494, the dial-plate of such a clock is represented ; in which there 
 is an opening, a h c d, below the centre. Through this opening, part of a flat 
 plate appears, on which the 12 hours are engraved, and divided into 
 quarters. This plate is contiguous to the back of the dial -plate, and turns 
 round in 12 hours ; so that the true hour or part thereof, appears in the 
 middle of the opening, at the point of an index. A, which is engraved on 
 the face of the dial-plate. B is the minute-hand^ as in a cdmmon clock, 
 going round through all the 60 minutes on the dial in an hour ; and in that 
 time, the plate seen through the opening abed shifts one hour under the 
 fixt, engraven index A. By these means the hour and minute may be 
 always known at whatever time the dial-plate i? viewed. In this plate is 
 another opening, efgh, through which the seconds are seen on a fiat 
 
AND MACHINIST. 
 
 491 
 
 movable ring, almost contiguous to the back of the dial-plate, and as the 
 ring turns round, the seconds upon it are shown by the top point of a 
 fleur-de-lis C, engraved on the face of the dial-plate. 
 
 Fig. 495 represents the wheels and pinions in this clock. A is the first 
 or great wheel; it contains 120 teeth, and turns round in 12 hours. On 
 its axis is the plate on which the 12 hours above-mentioned are engraved. 
 This plate is not fixed on the axis, but is only put tight upon a round part 
 thereof, so that any hour, or part of an hour, may be set to the top of the 
 fixed index A, fig. 494, without affecting the motion of the wheel. For this 
 purpose, twelve small holes are drilled through the plate, one at each hour, 
 among the quarter divisions ; and by putting a pin into any hole in viewg 
 the plate may be set, without affecting any part of the w^heel-work. This 
 great wheel A, of 1 20 teeth, turns a pinion B, of ten leaves, round in an 
 hour; and the minute-hand B, fig. 494, is on the axis of this pinion, the 
 end of the axis not being square but round, that the minute-hand may he 
 turned occasionally upon it without affecting any part of the movement. 
 On the axis of the pinion B is a wheel C of 120 teeth, turning round in 
 an hour, and turning a pinion D, of six leaves, in three minutes ; for three 
 minutes is a twentieth part of an hour, and 6 is a twentieth part of 120. 
 On the axis of this pinion is a wheel E of 90 teeth, going round in three 
 minutes, and keeping a pendulum in motion that vibrates seconds, by 
 pallets, as in a common clock, where the pendulum-wheel has only 30 teeth, 
 and goes round in a minute. But as this wheel goes round only in three 
 minutes, if it be wanted to show the seconds, a thin plate must be divided 
 into 3 times 60, or 180 equal parts, and numbered 10, 20, 30, 40, 50, 60 ; 
 10, 20, 30, 40, 50, 60; 10, 20, 30, 40, 50, 60; and fixed upon the same 
 axis with the wheel of 90 teeth, so near the back of the dinl-plato, as 
 only to turn round without touching it : and these divisions will show tlie 
 seconds through the opening efgli in the dial-plate, as they slide gradually 
 round below the point of the fixed fleur-de-lis C. 
 
 As the great wheel A, and pulley on its axis, over wliicli 
 the cord goes, (as in a common thirty-hour clock,) turns round 
 only once in twenty-four hours, this clock will go a week witli 
 a cord of common length, and always have the true hour, or 
 part of that hour, in sight at the upper end of the fixed index 
 A on the dial-plate. 
 
 There are two advantages which Mr. Ferguson's clock has 
 beyond Dr. Franklin's : but it has two disadvantages of which 
 his clock is free. For in this, although the twelve-hour wheel 
 turns the minute index B, yet if that index be turned by hand 
 to set it to the proper minute for any time, it wall not move 
 the twelve-hour plate to set the corresponding part of the 
 hour even with the top of the index A : and therefore, after 
 having set the minute index B right by hand, the hour-plate 
 must be set right by means of a pin put into the small hole 
 in the plate just below the hour. It is true there is no great 
 disadvantage in this ; but the pendulum -wheel having ninety^ 
 teeth instead of the common number thirty, may probably 
 make some difference to the scapement, on account of the 
 smallness of the teeth ; and it is certain that it will cause the 
 
492 THE Oi’ERATIVE MECHANIC 
 
 pendulum-ball to describe but small arcs in its vibrations, 
 Some men of science think small arcs are best ; but where- 
 fore we know not. For whether the ball describes a large or 
 a small arc^ if the arc be nearly cycloidal, the vibrations will 
 be performed in equal times ; the time therefore will depend 
 entirely on the length of the pendulum-rod, not on the length 
 of the arc the ball describes. The larger the arc is, the 
 greater the momentum of the ball; and the greater the 
 momentum is, ib.e less will the time of the vibrations be 
 affected by any unequal impulse of the pendulum- wheel upon 
 the pallets. 
 
 The greatest objection to Mr. Ferguson’s clock is, that 
 the weight of the fiat ring on which the seconds are engraved, 
 ' will load the pivots of the axis of the pendulum-wheel with a 
 great deal of friction, which ought by all possible means to 
 be avoided ; and yet one of these clocks, recently made, goes 
 very well, notwithstanding the weight of this ring. This 
 objection, however, can easily be remedied by leaving it out; 
 for seconds are of very little use in common clocks not made 
 for astronomical observations; and table clocks never have 
 them. 
 
 Having thus described this clock, we shall next proceed to 
 give a description of a clock, by the same ingenious mechanic, 
 for showing the apparent daily motions of the sun and moon, 
 the age and phases of the moon, with the time of her coining 
 to the meridian, and the times of high and low water, by 
 having only two wheels and a pinion added to the common 
 movement. 
 
 Mr. Ferguson’ s clock for exhibiting the apparent daily 
 
 motions of the sun and moon^ and state of the tides, B^c. 
 
 The dial-plate of this clock is represented by fig. 496. It contains all 
 the twenty-four hours of the day and night. S is the sun, which serves as 
 an hour index, by going round the dial-plate in twenty-four hours ; and M 
 is the moon, which goes round in twenty-four hours fifty minutes and a 
 half, from any point in the hour circle to the san\e point again, which is 
 equal to the time of the moon’s going round in the heavens, from the 
 meridian of any place to the same meridian again. The sun is fixed to 
 a circular plate, as fig. 497, and carried round by the motion of the plate, 
 on which the twenty-four hours are engraven, and within them is a circle 
 divided into twenty-nine and a half equal parts for the days of the moon’s 
 age, accounted from the time of any new moon to the next after ; and 
 each day stands directly under tlie time (in the twenty-four hour circle) 
 of the moon’s coming to the meridian, the twelve under the sun standing 
 for mid-day, and the opposite tv^elve for mid-night. Thus, when the moon 
 is eight days old, she comes to the meridian at half an hour past six in the 
 afternoon ; and when she is sixteen days old, she comes to the meridian at 
 one o’clock in the morning. The moon M, fig. 496, is fixed to another 
 circular plate, of the same diameter with that which carries the sun; and 
 
496 
 
 FL.74 
 
AND MACHINIST. 
 
 493 
 
 tliis moon-plate turns round in twenty-four hours fifty minutes and a halfi 
 It is cut open, so as to show some of the hours and days of the moon’s 
 age ; on the plate below it that carries the sun, and across this opening at 
 a and h are two short pieces of small wire in the moon-plate. The wire a 
 shows the day of the moon’s age, and time of her coming to the meridian, 
 on the plate below it that carries the sun ; and the ware h shows the time of 
 high water for that day, on the same plate. These wires must be placed as 
 far from one another, as the time of the moon’s coming to the 'meridian 
 dilfers from the time of high-water at the place where the clock is intended 
 to serve. At London-bridge it is high water when the moon is two hours 
 and a half past the meridian. 
 
 Above this plate that carries the moon, there is a fixed plate N, supported 
 by a wire A, the upper end of which is fixed to that plate, and the lower 
 end is bent to a right angle, and fixed into the dial-plate at the low'ermost 
 or midnight tw’elve. This plate may represent the earth, and the dot at L, 
 London, or any other place at which the clock is designed to show the 
 limes of high and low water. 
 
 Around this oiate is an elliptical shade upon the plate that carries the 
 moon M ; the highest points of this shade are marked High Water and the 
 lowest points Low Water : as this plate turns round below the fixed plate N, 
 the high and low’ w’ater points come successively even with L, and stand 
 just over it at the times w’hen it is high or low’ w’ater at the given placed 
 which times are pointed out by the sun S, among the twenty-iour hours on 
 the dial-plate : and, in the atch of this plate, above twelve at noon, is a 
 plate H, that rises and falls as tlie tide does at the given place. Thus, when 
 it is high water, (suppose at London,) one of the highest points of the 
 elliptical shade stands just over L, and the tide place II is at its greatest 
 height : and w hen it is low W'ater at London, one of the lowest points of the 
 elliptical shade stands over L, and the tide place 11 is quite dow’n, so as to 
 disappear beyond the dial-plate. As the sun S goes round the dial-plate 
 in 24 hours, and the moon M goes round it in 24 Irours 50§ minutes, the 
 mmon goes so much slower than the sun as only to make 28f revolutions 
 in the time the sun makes 29f ; and therefore the moon’s distance from 
 the sun is continually changing; so that at w’hatever time the sun and 
 moon are together, or in conjunction, in 29i- days afterwards they w’ill be 
 in conjunction again. Consequently the plate that carries the moon moves 
 so much slower than the plate that carries the sun, as always to make the wire 
 a shift over one day of the moon’s age on the sun’s plate in 24 hours. 
 
 In the plate that carries the moon, there is a round hole ?a, through w’hich 
 the phase or appearance of the moon is seen on the sun’s plate, for every 
 day of the moon’s age from change to change. When the sun and moon 
 are in conjunction, the whole space seen through the hole m is black : 
 when the moon is opposite to the sun (or full) all that space is white ; when 
 she is in either of her quarters, the same space is half black and halfw’hite; 
 and different in all other positions, so as the w’hite part may resemble the- 
 visible or enlightened part of the moon for every day of her age. 
 
 To show these various appearances of the moon, there is a black shaded 
 space, fig. 497, as N /F i, on the plate that carries the sun. Wl\en the sun 
 and moon are in conjunction, the whole space seen through tne round hole 
 is black, as at N ; when the moon is full, opposite to the sun, all the space 
 seen through the round hole is white,- as at F ; when the moon is in her 
 first quarter, as at f, or in her last quarter, as at I, the hole is only half 
 shaded ; and more or less accordingly for each position of tne moon, with 
 regard to her age ; as is abundantly plain by the figure. 
 
 The wheel-work and tide-w’ork of this clock arc represented by fig. 498, 
 
494 
 
 THE OrERATIVE MECHANIC 
 
 iu which A and B are two vvheels of equal diameters. A has 57 teelli, 
 its axis is hollow, it comes through the dial of the clock, and carries the 
 sun-plate with the sun, S, in fig 496. B has 59 teetli, its axis is a solid 
 spindle, turning within the hollow axis of A, and carrying the moon-plate 
 W'itli the moon, M, in fig. 496. A pinion C, of 19 leaves, takes into the 
 teeth of both the wheels, and turns them round. Tliis pinion is turned 
 round, by the common clock-work, in eight hours, and as 8 is a third 
 part of 24, so 19 is a third part of 57 ; and therefore the wdieel A of 57 teeth, 
 that carries the sun, will go round in 24 hours exactly. But as the same 
 pinion C (that turns the wheel A of 57 teeth) turns also the w'heel B of 59 
 teeth, this last wheel will not turn round in less than 24 hours 50 ^ minutes 
 of time ; for as 57 teeth are to 24 hours, so are 59 teeth to 24 liours 50§ 
 minutes, very nearly. 
 
 On the back of the moon-wheel of 59 teeth is fixed an elliptical ring D, 
 which, as it turns round, recoils and lets down a lever EF, whose centre of 
 motion is on a pin at F ; and this, by means of an upright bar G, raises and 
 lets down the tide-plate H, twice in the time of the moon’s revolving from 
 the meridian to the meridian again. The upper edge of this plate is shown 
 at H, in fig. 496, and it moves betv/een four rollers, R R R R, in fig. 498. 
 
 Mr. Ferguson states that he made one of these clocks to go 
 by the movement of an old watch in the following manner: 
 to the end of the axis of the first or great wheel of a 
 watch, which goes round in four hours, he put a wheel of 
 20 teeth to turn a wheel of 40 teeth on the axis of the 
 pinion C : by which means, that pinion turned round in eiglit 
 hours, the wheel A in 24 hours, and the wheel B in 24 hours 
 50:V minutes. 
 
 The writer of the different branches of 14 orology in Dr. Rees ’s 
 Cyclopccdia states, that there is an inaccuracy in the numbers 
 of the wheel-work adopted in the dial-work of this clock, 
 which would render it too imperfect to be used for a consider- 
 able length of time without a new rectification, even provided 
 the motions of the sun and moon, or, more properly speaking, 
 of the earth and moon, were quite equable, as the construc- 
 tion supposes, which inaccuracy, he states, may thus be 
 explained. 
 
 “ As tlie pinion of 19 drives both the wheels of 57 and 59, when the former 
 has performed a revolution in a solar day, the latter falls two teeth short of 
 a revolution, which it completes not until two teeth of the second revolution 
 of the wheel 57 have been again impelled, so that in every 24 hours the 
 little moon loses of its revolution, which is a part of a relative retrograde 
 motion, as it regards any point for instance, the upper hour xii, in the solar- 
 plate, so that as often as 2 are contained in 59, so many day-spaces 
 must there be on tlie solar-plate, figured in a retrograde direction, as the 
 figures regard the principal plate ; but the value of is 294 exactly, which 
 number of days measures the lunation according to these wheels exactly : 
 there is, therefore, a monthly error of 44™ 3® almost, which will amount to 
 nearly an entire day in the short space of about 32 lunations. 
 
 “ But there is, moreover, a practical objection to the two wheels, 57 and 
 59, being both driven by the same pinion of 19, which is, that being of the 
 same diameter, the distance between their teeth is not the same in both, one 
 
AND MACHINIST. 
 
 495 
 
 behio- and the other : of a semicircle, supposing their teetli and 
 
 spaces to be respectively equal to one another, but if both wheels are cut in 
 the cutting-engine by the same cutter, the inequality will fail in the teeth 
 entirely ; in either cases, the action of one of the teeth must be bad if the 
 other is properly proportioned, and periodic jerks vrill be the consequence, 
 which, in wheel-work going by a clock or watch movement, ought to be 
 avoided. Whether or not Mr. Ferguson had the dial of the clock at 
 Hampton Court in his eye when he contrived the simple mechanism of this 
 clock, we will not undertake to affirm; but we think it extremely probable 
 that he had, particularly as he has copied the position of the annular train 
 in another of his clocks. Being in the habit of calculating numbers proper 
 for representing given periods of time in clocks, watches, orreries, &c. w e 
 have turned our thoughts towards the improvement of this clock, as well 
 as of other pieces of mechanism, so far as relates to accuracy ; and beg 
 leave to lay before the reader the alteration that has occurred to us, for 
 rendering the clock before us more perfect than it is in the state above described. 
 
 “When describing the Hampton Court clock, we endeavoured to prove 
 that when the moon’s age is indicated by the difference of the velocities of 
 the two hands, moving in the same direction, and representing the sun 
 and moon, the latter ought to pass the xii o’clock point, on each day 50“ 
 473 nearly later than on the preceding day ; but by Mr. Ferguson’s calcu- 
 lations we see the daily retrogradation is 50™ 526, and the difference 
 .053 amounts to an entire day’s motion in a little more than 952 days ; or 
 somewhat upwards of 32 lunations, as we have stated. What therefore 
 we want, in this case, is a couple of divisible numbers that shall be to 
 each other very nearly in the ratio of 24^ to 24^' 50™ 473, which numbers, by 
 a peculiar arithmetical process become farhiliar to us by practice, wm have 
 determined to be 2368 : 2451. These are the nearest possible numbers 
 that can be got without ascending higher in the scale of continual ratios, and 
 are luckily capable of reduction into composite numbers thus ; 2368 taken 
 as a product is equal to 74 x 32 and 2451 = 57 x 43 ; therefore the train 
 X fA wall be the wheel-work required ; the solar wffieel of 74 teeth being 
 made to revolve with a tube as an arbor in 24 hours, by the clock move^ 
 ment, must impel the wheel of 43 placed on a stud, or otherwise on the 
 front plate of the frame, at one side of it, and this wheel of 43 must have 
 the next driver, 32, pinned to it, to impel the last wheel, 57, or lunar 
 wheel, placed on a solid arbor, concentrically behind the solar wheel, 
 according to Mr. Ferguson’s position, and the dials and other designs of 
 the clock face may remain precisely as described ; so that instead of the 
 pinion of 19 impelling two unequal wheels at once, we shall have a pair of 
 small w'heels pinned together, one impelled by, and the other impelling its 
 fellow, where the motion must be taken from an arbor of twelve hours, 
 carrying a wheel of 37 to actuate the 74 in twenty-four hours, instead of 
 from one of eight hours, as Mr. Ferguson proposed ; w'hich mode is equally 
 practicable. 
 
 “ As a proof of the accuracy of our calculation, we have by direct propor- 
 tion as 2368 ; 2451 : • 24^: 24 ^ 50™ 4729729, &c : hence the deviation from 
 the data is here only 0000271 of a minute in each lunar day, which will 
 not amount to an error of an entire day in less than 1,862,472 such days, 
 and therefore, may be assumed as no bad substitute of the truth itself ; see- 
 ing the clock will never be expected to go so long without clearing or stop- 
 page from some external cause. 
 
 “ Should it occur to the reader that 32 lunations constitute a period long 
 enough for the clock of Mr, Ferguson to go, before a new rectiheation, w’e 
 beg leave to suggest to him, that in the space of a lunar day there are two 
 
THE OPERATIVE MECHANIC 
 
 406 
 
 tides and two ebbs, consequently an error of three-quarters of an hour in eacli 
 lunation will place the tide-plate H, three hours wrong in the space of about 
 four months, and in nearly eight months an high water will be changed into 
 low water, and the reverse in the next eiglit months, which is certainly an 
 indispensable error. 
 
 “ That the clock-maker may not be at a loss how to apply the remedy we 
 have proposed for the inaccuracy of Mr. Ferguson’s solar and lunar wheels, 
 we shall conclude our description of the clock before us with an account of 
 the exact dimensions of the parts proposed to be substituted. If we take 
 tire wiieel of communication of 37 teeth at 12 per inch, measured at the 
 pitch line, its geometrical diameter will be 98 or of an inch, and its 
 practical diameter, with the addendum for the ends of the teeth, 1*04; the 
 w’heel of 74 being double will have its geometrical diameter equal to 1-96, 
 and its practical one 2-02 ; tlie fellow of this last or solar-wheel has its 
 geometrical diameter by the same proportion, 1.14, and its practical one 
 1.20 : the distance of the stud from the centre of motion of the solar and 
 lunar wheels, must necessarily be the sum of the geometrical radii of these 
 two last wheels, namely, 1’96 + 1 .14-f-2^ which is =1*55; again the sum 
 of tlie geometrical radii of the remaining two wheels, 32 and 57, must be 
 also equal to 1‘55, in order that the centres of motion of the solar and lunar 
 wheels may exactly coincide ; but a wheel of a geometrical diameter equal to 
 f-oo or 3.10 inches and of 32 + 57^ or 89 teeth, •wall have only about 
 nine teeth per inch, and the practical diameters of wheels 32 and 57, by the 
 same, will be respectively 1-21 and 2-1. The calliper suitable for these 
 ]u-oportions and dimensions is given, of their full size and dimensions, in 
 .hg. 498*, which needs no farther explanation, except that the wheels 43 and 
 32 are so nearly of a size that one circle represents both, as pinned together, 
 and revolving with a contemporary motion round a stud or screw in their 
 centre, going into the front plate of the clock-frame. The small wheel of 32 
 acts deeper into the teeth of its fellow than the 43, by reason of having larger 
 teeth than tlie other, though the wheel is of the same size.’’ 
 
 Ill the year 1803, the Society for tlie Encouragement of Arts, 
 &c. presented to Mr. John Prior, of Nessfield, Yorkshire, a 
 reward of thirty guineas on account of his contrivance for the 
 striking part of an eight-day clock. As this invention is 
 likely to be useful we shall describe it here. It consists of a 
 wheel and fly, with six turns of a spiral line, cut upon the 
 wheel for the purpose of counting the hours. The pins below 
 this spiral elevate the hammer, and those above are for the 
 use of the detent. This single wheel serves the purpose of 
 count- wheel, pin-wheel, detent- wheel, and the fl}^- wheel, and 
 has six revolutions in striking the twelve hours. If we suppose 
 a train of wheels and pinions used in other striking parts to be 
 made without error, and that the wheels and pinions would 
 turn each other without shake or play, then, allowing the above 
 supposition to be true, (though every mechanic knows it is not^) 
 Mr. Prior’s striking part would be found six times superior to 
 others, in striking the hours 1, 2,5,7? 10, II ; twelve time? 
 superior in striking 4, 6, 8 ; and eighteen times in striking 3 
 9, and 12. In striking 2, the inventor purposely made an 
 
AND MACHINIST 
 
 497 
 
 imperfection equal to the space of three teeth of the wheel ; 
 and in striking 3, an imperfection of nine or ten teeth ; and 
 yet both these hours are struck perfectly correct. The flies in 
 clocks turn round at a mean^ about sixty times for every knock 
 of the hammer, but this turns round only three times for the 
 same purpose : and suppose the pivots were of equal diameters, 
 the influence of oil on them would be as the number of 
 revolutions in each. It would be better for clocks if they 
 gave no warning at all, but the snail piece to raise a weight 
 somewhat similar to the model Mr. P. sent for the inspection 
 of that respectable society. 
 
 The striking part of this clock is represented in fig. 499. 
 
 A, the large wheel, on the face of which are sunk or cut the six turns of a 
 spiral. 
 
 B, the single worm screw, wliich ads on the above wheel, and moves 
 the fly C. 
 
 D, the spiral work of the wheel A. The black spots show the grooves 
 into which the detents drop on striking the hour. 
 
 E, the groove into which the locking piece F drops when it strikes 1, 
 and from which place it proceeds to the outward parts of the spiral in the 
 progressive hours, being thrown out by a lifting piece H at each hour ; the 
 upper detent G being pumped oflf with the locking piece F, from the pins on 
 the wheel A. 
 
 In striking the hour of 12, the locking piece, having arrived at the outer 
 spiral at H, rises up an inclined plane, and drops by its own weight into 
 the inner circle, in which the hour 1 is to be struck, and proceeds on in a 
 progressive motion through the different hours till it comes again to 12. 
 
 I, the hammer-work made in the common way, which is worked by thirteen 
 pins on the face of the spiral. 
 
 Fig. 500, K. the thirteen pins on the face of the spiral, which work the 
 hammer-work. 
 
 ^ L, the outer pins which lock the detent. 
 
 ’ M, the pump spring to the detent. 
 
 In the fourth century, an artist named James Dondi con- 
 structed a clock for the city of Padua, which was long con- 
 sidered as the wonder of the period. Besides indicating the 
 hours, it represented the motions of the sun, moon, and 
 planets, as well as pointed nut the different festivals of 
 the year. On this account Dondi obtained the surname of 
 Horologio, which became that of his posterity. A short time 
 after, William Zelander constructed for the same city a 
 clock still more complex ; which was repaired in the sixteenth 
 century by Janellin Turrianus, the mechanist of Charles V. 
 
 But the clocks of the cathedrals of Strasburgh and of Lyons 
 are much more celebrated. That of Strasburgh was the work 
 of Conrad Dayspodius, a mathematician of that city, who 
 finished it about 1573. The face of the basement of this 
 clock exhibits three dial-plates ; one of which is round, and 
 consists of several concentric circles ; the two interior ones of 
 
 2 K 
 
49B 
 
 THE OPERATIVE MECHANIC 
 
 which perform their revolutions in a year, and serve to mark 
 the days of the year, the festivals, and other circumstances of 
 the calendar. The two lateral dial-plates are square, and 
 serve to indicate the eclipses both of the sun and the moon. 
 
 Above the middle dial-plate, and in the attic space of the 
 basement, the days of the week are represented by different 
 divinities, supposed to preside over the planets from which 
 their common appellations are derived. The divinity of the 
 current day appears in a car rolling over the clouds, and at 
 midnight retires to give place to the succeeding one. Before 
 the basement is seen a globe borne on the wings of a pelican, 
 around which the sun and moon revolved ; and which in that 
 manner represented the motion of these planets, but this 
 part of the machine, as well as several othei-s, has been de- 
 ranged for a long time. The ornamental turret, above this 
 basement, exhibits chiefly a large dial in the form of an astro- 
 labe ; which shows the annual motion of the sun and moon 
 through the ecliptic, the hours of the day, &c. The phases 
 of the moon are seen also marked out on a particular dial- 
 plate above. This work is remarkable also for a considerable 
 assemblage of bells and figures, which perform different mo- 
 tions. Above the dial-plate last mentioned, for example, the 
 four ages of man are represented by symbolical figures ; one 
 passes every quarter of an hour, and marks the quarter by 
 striking on small ])ells ; these figiii’es are followed by Death, 
 wlio is expelled by Jesus Christ risen from the grave : who, 
 however, permits it to sound the hour, in order to warn man 
 that time is on the wing. Two small angels perform move- 
 ments also ; one striking a bell with a sceptre, whilst the 
 other turns an hour-glass at the expiration of an hour. In 
 the last place, this work is decorated with various animals, 
 which emitted sounds similar to their natural voices ; but 
 none of them remain, except the cock, which crows imme- 
 diately before the hour strikes, first stretching out its neck 
 and clapping its wings. Indeed it is to be regretted that a 
 great part of this curious machine is now entirely deranged. 
 
 The clock of the cathedral of Lyons is of less size than that 
 of Strasburgh, but is not inferior to it in the variety of its 
 nxovements ; it has the advantage also of being in a good con- 
 dition. It is the work of Lippius de Basle, and was exceed- 
 ingly well repaired in the last century by an ingenious clock- 
 maker of Lyons, named Nourisson. Like that of Strasburgh-, 
 it exhibits, on different dial-plates, the annual and diurnal 
 progress of the sun and moon, the days of the year, their 
 length, and the whole calendar, civil as well as ecclesiastic. 
 
AND MACIUNIST. 
 
 499 
 
 The days of the week are indicated by symbols more analo- 
 gous to the place where the clock is erected ; the hours are 
 announced by the crowdng of a cock, three times repeated, after 
 it has clapped its wings, and made various otlier movements. 
 When the cock has done crowing, angels appear, who by 
 striking various bells, perform the air of a hymn ; the annun- 
 ciation of the virgin is represented also by moving figures, and 
 by the descent of a dove from the clouds ; and after this 
 mechanical exhibition the hour strikes. On one of the sides of 
 the clock is seen an oval dial-plate, where the hours and 
 minutes are indicated by means of an index, which lengthens 
 or contracts itself, according to the length of the semidiametcr 
 of the ellipsis over which it moves. 
 
 A very curious clock, the work of Martinot, a celebrated 
 clock-maker of the seventeenth century, was formerly to 
 be seen in the royal apartments at Versailles. Before it 
 struck the hour, two cocks on the corner of a small edifice 
 crowed alternately, clapping their wings ; soon after, two 
 lateral doors of the edifice opened, at which appeared two 
 figures bearing cymbals, beat upon bj^ a kind of guards with 
 clubs. When these figures had retired, the centre door was 
 thrown open, and a pedestal, supporting an equestrian statue 
 of Louis XIV., issued from it, wLile a group of clouds separat- 
 ing, gave a passage to a figure of Fame, which came and 
 hovered over the statue. An air was then performed by bells ; 
 after which the two figures reentered, the two guards raised 
 up their clubs, which they had lowered as if out of respect to 
 the presence of the king, and the hour was then struck. 
 
 While, however, we have thought it right to describe these 
 ingenious performances of foreign artists, we must not neglect 
 to mention the equally ingenious workmanship of some of our 
 own countrymen. We now refer to two clocks made by 
 English artists, as a present from the East India Company to 
 the Emperor of China. These two clocks are in the form of 
 chariots, in each of which a lady is placed in a fine attitude, 
 leaning her right hand upon a part of the chariot, under which 
 appears a clock of curious workmanship, little larger than a 
 shilling, which strikes and repeats, and goes for eight days. 
 Upon the lady’s finger sits a bird, finely modelled and set 
 with diamonds and rubies, with its wings expanded in a flying 
 posture, and which actually flutters for a considerable time by 
 touching a diamond button below it ; the body of the bird, in 
 which are contained the wheels that animate it as it were, is 
 less than the 16th part of an inch. The lady holds in her 
 
 2k2 
 
500 
 
 THE OPERATIVE MECHANIC 
 
 left hand a golden tube, little thicker than a large pin, on 
 the top of which is a small round box, to which is fixed a 
 circular ornament not larger than a sixpence, set with dia- 
 monds, which goes round in or near three hours in constant 
 regular motion. Over the lady’s head is a double umbrella, 
 supported by a small fluted pillar the size of a quill, and 
 under the larger of which a bell is fixed, at a consider- 
 able distance from the clock, with which it seems to have 
 no connection, but from which a communication is secretly 
 conveyed to a hammer that regularly strikes the hour, and 
 repeats the same at pleasure, by touching a diamond button 
 fixed to the clock below. At the feet of the lady is a golden 
 dog. 
 
 In a work like the present, however we may wish to pursue 
 this interesting subject through its progressive steps of im- 
 provement, and to do justice to the numerous scientific and 
 ingenious men who have from time to time effected those 
 improvements, we are compelled to confine ourselves within 
 certain limits, which preclude us from entering more fully 
 into detail in this article ; we therefore refer such of our 
 readers, who wish to pursue the subject, to the catalogue ol 
 writings in Dr. Young’s Natural Philosoph}^ 
 
 We shall next proceed to give a description of the mecha- 
 nism of an ordinary watch, and to annex thereto a useful set 
 of tables, published originally by Mr. W. Stirt. 
 
 WATCHES. 
 
 Figure 501 represents the interior works of an ordinary watch with the 
 crown-wheel escapement, as they remain on the pillar-plate when the uppei 
 part of the frame, shown by fig. 505, is unpinned and removed ; and fig. 50?, 
 which is a section of the whole frame and its contents, shows the connection 
 of all the parts, as though the calliper were in one right line. These two 
 figures, by having the same letters of reference, mutually explain each other. 
 The mainspring which actuates all the wheels and pinions, that are called, 
 in one general term, the movement, is contained in the circular box a, seen 
 in the different views in the separate figs. 501, 502, and 508, in the last of 
 which its parts are given in a detached state, viz. the box ; the relaxed spring 
 immediately above lying in a spiral form ; the arbor with its pin, on which 
 the interior end of the spring is hooked, and the lid through which the 
 pivot of the arbor penetrates; this spring is forced into the box by a tool on 
 purpose when it is strong ; and then the exterior end is hooked to a pin in 
 the circular edge of the box, so that if the box is made to turn round while 
 the arbor is held fast, the spring begins to coil at the centre, and is thereby 
 said to be wound up. The same effect would be produced if the box were 
 held fast, and the arbor only were turned ; but in the latter case the chain, 
 which requires to be uncoiled from the spring-box as this spring is wound up, 
 would remain unmoved ; it is necessary therefore that the box be tumeci 
 while the arbor is at rest, which is thus effected : one end of the chain is 
 
WATCHJES 
 
 n.75 
 
 5ol 
 
 From 501 to 509 
 
 505 
 
 4 S-mM^ sc 3 Si Smmd 
 
\r 
 
 
 
 
 Ti'i/^ '’H 
 
 
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 i-' -^!’-v • • • ?. 
 
 V ‘11 
 
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 J 
 
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 '!'■ V..' ; 
 
 w; .v- 1 ! ,. • . ■'-:: n-j 
 
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 Vi‘ .'i i'M 
 
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 ■ -■■'. ,Jr.’cr^ . V 
 
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 K 'V iii ' >'•■' 'k^ii'sc 
 
 
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 "Aus:?^ 
 
 ■ ' . .: -;i ms ■ <:,v- ?K^tiS;a: 4 , 
 
 
AND MACHINIST. 
 
 301 
 
 made fast to the side of the spring-box, and th© other to the fusee h, after 
 being coiled several times round the circumference of the box ; then as the 
 square end of the spring-box arbor is held by the small ratchet and click 
 c seen on the reversed face of the pillar-plate in fig. 507, so that it cannot 
 revolve, it is obvious that inserting a key on the square of the fusee arbdr, 
 and turning it in a proper direction, will wind the chain upon the spiral 
 groove of the fusee, while it is unwound from the box ; and during this 
 operation, the spring will be coiled up to the centre of the box, or put into its 
 state of greatest tension for pulling the fusee back again. The rapid motion 
 which the fusee would have in a retrograde direction when pulled by the 
 whole force of the coiled spring, is prevented by the train of wheel-work and 
 balance, thus : the great w'heel d is not fast to the thick end of the fusee, as 
 appears in the drawings, but carries a click and click-spring Zy as seen in 
 %. 503, while the ratchet-wlieel, seen in fig. 504, is made fast to the fusee ; 
 the consequence of which contrivance is, that while a key applied to the 
 fusee arbor winds up the watch and fills the fusee groove with the chain, 
 until the guard driven by it catches the beak at the small end of the fusee, the 
 click, in fig. 503, slides over the teeth of the ratchet in fig. 504, without acting 
 on them, and thus leaves the great wheel d at rest, in connection wdth the 
 pinion e on the centre or minute wheel arbor ; but when the spring acts on , 
 the fusee in a contrary direction, the click attached to the great wheel is 
 laid hold of by the teeth of the ratchet, which thu^ makes it fast to the end 
 of the fusee ; or in other words, until the spring wants winding up again, 
 which usually happens once in 28 or 30 hours : but it is commonly wound 
 up once in 24 hours more or less. The action of the great wheel d, on the 
 pinion e, is that of a long lever driving a short one ; or this wheel may be 
 said to act under a mechanical disadvantage, when an increase of velocity, 
 but a loss of power, is experienced by the pinion ; again, on the same cen- 
 tral arbor of this pinion e is rivetted the centre wheel/, which revolves in an 
 exact hour, as we shall see presently, and this wheel drives the pinion g-, 
 on the arbor of the third wheel A, also with a mechanical disadvantage, for 
 the force it imparts to the pinion i, on the arbor of the contrate wheel, is 
 again diminished in the ratio of the diameter of the wheel to that of its 
 pinion; thus the force of the mainspring is continually diminishing, as it is 
 transmitted through the train, and when the contrate wheel comes to be 
 actuated, it has just force enough to drive the horizontal pinion on the 
 balance wheel /, so that the alternate impulse given by its teeth to the pal- 
 lets of the balance verge are just sufficient to perpetuate the oscillation from 
 right to left, under all the obstacles of friction, dirt, wear, and the air’s 
 resistance. It is a curious fact that the crown-wheel escapement, though the 
 oldest that w^e know of, is still the most in use in common watches, probably 
 from the facility with which it is constructed ; for certainly it is more under 
 the influence of the irregularities of tl)e mainspring’s force than any other 
 escapement. The properties and action of this escapement have been 
 minutely explained in page 516 of the article Escapement, with reference 
 to fig. 523, to which explanation and figure we request our reader’s 
 attention. 
 
 In order that the force applied to pallets of the verge at 
 each oscillation may not sensibly vary, it was found necessary 
 to equalize, as much as possible, the variable forces of the 
 mainspring in its different states of tension ; and the most 
 practical way of doing this has been found, to convert the 
 cylinder on the arbor of the great wheel, which would have 
 
502 
 
 ^I Hii OI'ERAliVli: MKCHANIC 
 
 been proper for a gravitating body, used as a maintaining 
 power, into a figure of a parabolic form, that is, into a srdid, 
 generated by the revolution of a parabola, in order that, as 
 the force of the spring becomes greater by increased tension, 
 its action on the great wheel might be lessened in a similar 
 proportion, by a gradual decrease of the radius of the fusee, 
 round which the chain is wound, to impart the force thus 
 modified. Every separate spring, therefore, has not only its 
 average force proportioned to the balance it is destined to 
 actuate, when diminished by transmission through a given 
 train, but requires its scale of varying forces to be nicely 
 counteracted in every degree of tension by the shape of the 
 fusee ; and this is done by means of a tool, called a fusee ad- 
 justing tool, which is nothing more than a lever with a sliding 
 weight, attached to the square end of the fusee arbor, as re* 
 presented in fig. 509; for when the weight on the lever is 
 an exact counterpoise to the force of the mainspring in every 
 part of the successive revolutions of the fusee, as the spring is 
 wound up by the lever instead of a key, then the shape of the 
 fusee is proper, but not otherwise. Hence, whenever a new 
 mainspring is put to a watch, the fusee ought to be adjusted 
 in the fusee engine according as the adjusting tool determines. 
 
 The comparative forces of the spring at the extreme ends 
 of the fusee may be adjusted by the small ratchet c, on the 
 back of the pillar-plate in fig. 507, but when the spring is put 
 to a suitable degree of tension to act well at both extremities 
 of the fusee, it must not be altered by the ratches’ click, but 
 the intermediate forces must be equalized by a due shape 
 given to the fusee. We have insisted the more on this part 
 of the mechanism being attended to, because, as the primmn 
 mobile, it is the basis of all other motions. The number of 
 rounds that the spiral of the parabolic fusee may be cut into 
 depends on the length of the pillars of the frame, or, which is 
 the same thing, the shallowness of the watch. The French 
 frequently leave out the fusee, and attempt to equalize the 
 forces of the mainspring by tapering it ; and wdth detached 
 escapements, this mode may sometimes answer tolerably, but 
 with the crown-wdieel escapement a fusee is indispensable. 
 Again, the number of teeth in the great wheel, and in the centre 
 pinion, depends on the number of rounds in the spiral of the 
 fusee, 
 
 [ti a thirty-hours’ watch, with six turns of the fusee, the great wheel must 
 have or five times as many teeth as the centre pinion ; so that if this has 
 SIX leaves, the wheel must have 5 x G — liO teeth ; but if eight, then 5 x 8 —40; 
 if the spiral lias seven turns, the great wheel 48, and tlie pinion 12, then tlie 
 
AND MACHINIST. 
 
 503 
 
 time of going will be x7=28 hours; also, if there be 5^ turns on the 
 fusee, 50 teeth in the wheel, and 10 leaves in the pinion, the period of 
 going will be 27^ hours, or ^ x =5 x 5f = 27^ ; but if 24 hours only 
 were"required as the period, with six turns and a pinion of 12, the great 
 wheel would be required to have 48. 
 
 Thus when an alteration is made in either the pinion^ the 
 wheel, or the turns in the fusee, a corresponding variation 
 may be made in the others, to produce the same period of 
 going, but still the centre wheel revolves once in an hour. 
 In the commonest watches the pinions have only six leaves 
 each, which do not act so well as pinions of higher numbers ; 
 but in the best watches, and in all chronometers, the leaves 
 and teeth are more numerous. The pivot-holes, particularly 
 of the verge and escapement arbor, have jewels for tlie pur- 
 pose of diminishing the friction, in the best watches ; but de- 
 tached and remontoire escapements are the best correctives of 
 the unequal impulses given through the medium of the train 
 in the different states of its foulness. 
 
 The potence m, and small or counter potence n, that hold the pivots of 
 the balance-wheel, are small cocks seen in fig. 502, both in their attached 
 and detached states, and are screwed to the top or upper plate within the 
 frame ; but the springs, buttons, and joints of the case, are not exhibited, 
 as forming no part of the movement.. Fig. 505 represents the outer face of 
 the upper plate, with the balance p, the cock o, and balance-spring s, called 
 the pendulum-spring, from its having the properties of the pendulum; by 
 means of this spring, not only is the regulation made steady, but the adjust- 
 ment for time is effected. In every balance-spring there is a certain length, 
 to be taken as the effective length, by which the going of the watch to 
 which it is applied is limited to exact performance ; and when this length 
 is determined by experiment, a pin is put in the stud that holds the exterior 
 ends, as at 4, in fig. 505, to prevent its being altered ; but as the variation 
 of temperature will alter the momentum of the moving-balance, the effect 
 thereby produced is a loss of time in the rate, in hot weather, and a gain 
 in cold weather, by an alternate increase and decrease in the dimensions of 
 the balance itself, as well as by some alteration in the spring. To remedy 
 this defect, in an ordinary w'atch, the contrivance shown in fig. 506 is intro- 
 duced ; the wheel t is placed under the graduated circle r, seen in fig. .505, 
 and a circular rack u, fig. 506, that holds the curb or slit-piece 5, seen in 
 both figures, is moved by a sliding motion given to it, when a key is applied 
 to the squared arbor cf the figure circle, and thus the effective length of the 
 spiral spring is limited by the position of the curb 5 ; and according as the 
 key is turned forwards or backwards, towards the words ‘fast^ or ‘slow' 
 engraved on the cock, the shortened or lengthened spring alters the rate of 
 going, till the proper length is found that suits the season in question. 
 
 Ill Harrison’s time-piece the curb was moved by an expan- 
 sion-lever of two metals, that acted by means of the change 
 of temperature ; but in the best chronometers of more recent 
 dates, the compensating levers constitute the three portions 
 into which the rim of the balance is divided,* and the adjust- 
 
504 
 
 THE OPERATIVE MECHANIC 
 
 ment for time, as well as compensation for temperature, are 
 by means of heavy screws, which form a part of the moving 
 balance. In these more perfect machines, the length of the 
 spring, which is now made helical or cylindrical, is first 
 determined such, that the long and short vibrations are per- 
 formed in the same time, and this is called the isochronal 
 lengths, which is not afterwards altered by subsequent adjust- 
 ments. 
 
 Tlie last portion of the watch which demands our explanation is the dial- 
 work, for producing the hours and minutes ; this will be easily understood 
 by reference to figs. 502 and 507. When the pinion called the cannon- 
 pinion, seen near the minute-hand in fig. 502, is inserted on the arbor of 
 the hour or centre wheel, to which it fits rather tight by friction, it revolves 
 therewith in an hour, and receives the minute or hour hand on its protruding 
 squared end ; then this pinion drives the wheel x round a stud on the pillar- 
 plate, and with it a pinion w made fast to its centre ; which pinion again 
 drives a second wheel, v, round the tube of the cannon-pinion in twelve 
 hours ; and to this the hour-hand is attached. This diminution of twelve 
 revolutions from the cannon-pinion to the hour-wheel might be effected by 
 one pinion driving a single wheel of twelve times its number of teeth ; but 
 as the motion must be brought back to the centre of the dial again, two 
 more wheels, or a wheel and pinion, are necessary to be introduced,- and., 
 these are therefore made a part of the train, and no large wheel or smalb> 
 pinion is wanted, for the ratio 12; 1 may be more conveniently obtained 
 by two factors, viz. 4 : 1 and 3 : 1 ; thus, suppose the cannon-pinion 
 to have 15 leaves, its wheel may have 4x15=60 teeth for wheel x^ i | 
 
 60 
 
 and if wheel v be the same, its pinion will be -^^ = 20, and the train 
 
 60 60 
 T5 ^ 20 
 
 3 ' .'V 
 
 360 72 60 12 , , , . . . , ^ 
 
 — = — or — = — ■ or 12 ; so that when the pinions are fixed j 
 30 6 5 1 ^ 
 
 upon for the dial-work, the wheels are readily determined, and vice versa. \ 
 
 The following Tables, somewhat differently arranged, were 
 published by W. Stirt, an ingenious balance-wheel and fusee 
 cutter. J 
 
 f«| 
 
 A TABLE OF TRAINS FOR WATCHES ; ^ 
 
 Showing the Number of Turns on the Fusee and Teeth in the Balance- | 
 wheel, with the Beats in an Hour, and the number of Seconds in which * 
 the Contrate or Fourth Wheel revolves; for the easy Timing of Watches 
 by the Vibrations of the Pendulum. 
 
 9 Teeth in the Balance-wheel 
 
 Second wheel 58 6 Third wheel pin. 
 
 60 8 
 
 60 6 
 
 60 6 
 
 60 6 
 
 60 6 
 
 64 6 
 
 64 8 
 
 Third wheel 56 6 Contrate pin. .. 
 
 56 7 
 
 58 6 
 
 58 6 
 
 60 6 
 
 60 6 
 
 60 6 
 
 60 8 
 
 Contrate wheel 54 6 Balance pin. .. 
 
 80 6 
 
 52 6 
 
 56 6 
 
 54 6 
 
 60 6 
 
 54 6 
 
 80 6 
 
 Beats 14,616 in an hour 
 
 14,400 
 
 15,080 
 
 16,240 
 
 16,200 
 
 18,000 
 
 17,280 
 
 14,400 
 
 . Seconds 39 -^, in which the 4th 1 
 wheel revolves • • • J 
 
 60 
 
 3/| 
 
 3/| 
 
 36 
 
 36 
 
 331 
 
 60 
 
AND MACHINIST, 
 
 505 
 
 A Table of Trains for Watches continued. i 
 1 1 Teeth in the Balance-ivheel. 
 
 : Second wheel 48 6 Tliird wheel pinion. . . . 
 
 1 , Third wheel 45 6 Contrate pinion 
 
 ‘ Contrate wheel 70 6 Balance pinion 
 
 '| Beats 15,400 in an hour 
 
 1 Seconds 60, in which the 4th wheel revolves 
 
 54 6 
 45 6 
 65 6 
 16,087 
 534 
 
 54 6 
 50 6 
 60 6 
 16,500 
 48 
 
 56 7 
 45 6 
 78 6 
 17,160 
 60 
 
 56 6 
 54 6 
 54 6 
 16,632 
 42f 
 
 56 6 
 56 6 
 55 6 
 17,567 
 414 
 
 58 6 
 
 58 6 
 
 58 6 
 
 58 6 
 
 58 7 
 
 60 6 
 
 60 6 
 
 60 6 
 
 60 6 
 
 60 6 
 
 60 6 
 
 1 52 6 
 
 54 6 
 
 54 6 
 
 56 6 
 
 56 6 
 
 50 6 
 
 52 6 
 
 54 6 
 
 54 6 
 
 54 6 
 
 55 6 
 
 ! 52 6 
 
 52 6 
 
 54 6 
 
 54 6 
 
 56 6 
 
 52 6, 
 
 52 6 
 
 50 6 
 
 52 6 
 
 54 6 
 
 52 6 
 
 15,973 
 
 16,588 
 
 17,226 
 
 17,817 
 
 15,879 
 
 15,888 
 
 16,520 
 
 16;500 
 
 17,160 
 
 17,820 
 
 17,477 
 
 42i 
 
 44 
 
 44 
 
 39i 
 
 544 
 
 43 
 
 414 
 
 40 
 
 40 
 
 40 
 
 39 
 
 60 6 
 
 60 7 
 
 60 8 
 
 60 8 
 
 60 6 
 
 60 8 
 
 60 7 
 
 62 6 
 
 62 7 
 
 63 6 
 
 63 6 
 
 56 6 
 
 56 6 
 
 56 7 
 
 56 7 
 
 60 6 
 
 60 6 
 
 60 7 
 
 54 6 
 
 58 6 
 
 54 6 
 
 56 " 
 
 50 6 
 
 56 6 
 
 74 6 
 
 78 6 
 
 48 6 
 
 56 6 
 
 60 6 
 
 52 6 
 
 52 6 
 
 50 6 
 
 56 6 
 
 17,111 
 
 16,426 
 
 16,280 
 
 17,160 
 
 17,553 
 
 15,400 
 
 16,163 
 
 17,935 
 
 16,324 
 
 17,325 
 
 17,248 
 
 S8i 
 
 40 
 
 60 
 
 60 
 
 36 
 
 48 
 
 49 
 
 384 
 
 45 
 
 38 
 
 42i 
 
 64 6 
 
 64 6 
 
 65 7 
 
 70 8 
 
 70 7 
 
 72 8 
 
 72 7 
 
 80 8 
 
 75 10 
 
 72 9 
 
 72 9 
 
 50 6 
 
 52 6 
 
 62 7 
 
 54 7 
 
 63 7 
 
 63 7 
 
 64 7 
 
 72 8 
 
 72 9 
 
 66 8 
 
 60 B 
 
 50 6 
 
 52 6 
 
 59 7 
 
 68 6 
 
 58 7 
 
 54 6 
 
 58 7 
 
 68 8 
 
 66 8 
 
 60 6 
 
 54 6 
 
 16,296 
 
 17,625 
 
 15,250 
 
 16,830 
 
 16,408 
 
 16,035 
 
 17,142 
 
 16,830 
 
 13,200 
 
 13,200 
 
 11,880. 
 
 40^ 
 
 39 
 
 434 
 
 5.3^ 
 
 40 
 
 444 
 
 384 
 
 40 
 
 60 
 
 66 
 
 60 
 
 
 
 
 13 Teeth in 
 
 the Balance-wheel. 
 
 
 
 
 Second wheel 
 
 48 6 Third wheel pinions . . 
 
 48 6 
 
 52 6 
 
 54 6 
 
 54 6 
 
 54 6 
 
 i Third wheel 
 
 45 6 < 
 
 Contrate pinion 
 
 
 45 6 
 
 52 6 
 
 50 6 
 
 52 6 
 
 52 6 
 
 Cnnfrnf-f' 66 6 Rflianpp nininn . 
 
 
 68 6 
 
 52 6 
 
 50 6 
 
 48 6 
 
 50 6 
 
 Bpat.s 17.160 in an linnr.. . 
 
 
 
 17,680 
 
 16,925 
 
 16,274 
 
 16,224 
 
 16,900 
 
 Seconds 60, 
 
 in which the 4th wheel revolves 
 
 60 
 
 464 
 
 48 
 
 46 
 
 46 
 
 54 6 
 
 54 6 
 
 55 6 
 
 56 7 
 
 56 6 
 
 56 6 
 
 56 6 
 
 56 6 
 
 56 6 
 
 58 6 
 
 58 6 
 
 52 6 
 
 52 6 
 
 51 6 
 
 45 6 
 
 50 6 
 
 50 6 
 
 52 6 
 
 52 6 
 
 54 6 
 
 48 6 
 
 50 6 
 
 51 6 
 
 52 6 
 
 51 6 
 
 66 6 
 
 50 6 
 
 51 6 
 
 48 6 
 
 50 6 
 
 49 6 
 
 52 6 
 
 50 6 
 
 17,238 
 
 17,576 
 
 17,219 
 
 17,160 
 
 16,851 
 
 17,188 
 
 16,824 
 
 17,525 
 
 17,836 
 
 17,425 
 
 17,453 
 
 46 
 
 46 
 
 1 
 
 46| 
 
 60 
 
 46§ 
 
 464 
 
 444 
 
 444 
 
 424 
 
 464 
 
 4^1 
 
 60 6' 
 
 60 8 
 
 60 6 
 
 60 6 
 
 60 7 
 
 60 6 
 
 60 7 
 
 60 8 
 
 60 7 
 
 60 8 
 
 60 6 
 
 48 6 
 
 48 6 
 
 50 6 
 
 50 6 
 
 54 6 
 
 54 8 
 
 56 7 
 
 56 7 
 
 58 7 
 
 58 6 
 
 60 7 
 
 48 6 
 
 66 6 
 
 46 6 
 
 48 6 
 
 52 6 
 
 60 6 
 
 56 6 
 
 66 6 
 
 56 6 
 
 56 6 
 
 48 6 
 
 16,640 
 
 17,160 
 
 16,611 
 
 17,333 
 
 17,382 
 
 17,550 
 
 16,640 
 
 17,160 
 
 17,234 
 
 17,593 
 
 17,828 
 
 " 45 
 
 60 
 
 43 
 
 43 
 
 46| 
 
 54 
 
 524 
 
 60 
 
 50| 
 
 494 
 
 42 
 
 60 8 
 
 60 6 
 
 62 7 
 
 63 7 
 
 63 7 
 
 64 7 
 
 64 7 
 
 64 8 
 
 64 8 
 
 65 7 
 
 70 8 
 
 60 6 
 
 60 7 
 
 56 7 
 
 52 6 
 
 60 7 
 
 52 6 
 
 60 7 
 
 60 8 
 
 64 8 
 
 62 7 
 
 60 7 
 
 54 6 
 
 56 7 
 
 56 6 
 
 51 6 
 
 60 7 
 
 50 6 
 
 60 7 
 
 66 6 
 
 72 7 
 
 58 7 
 
 52 6 
 
 17,550 
 
 17,828 
 
 17,194 
 
 17,238 
 
 17,191 
 
 17,168 
 
 17.464 
 
 17,160 
 
 17,115 
 
 17,717 
 
 16,900 
 
 48 
 
 42 
 
 50| 
 
 46| 
 
 46| 
 
 46 
 
 454 
 
 60 
 
 564 
 
 43f 
 
 48 
 
 70 8 
 
 72 8 
 
 72 8 
 
 74 8 
 
 74 8 
 
 75 10 
 
 75 10 
 
 80 10 
 
 96 12 
 
 96 12 
 
 90 10 
 
 66 8 
 
 52 6 
 
 70 8 
 
 64 8 
 
 68 8 
 
 72 9 
 
 72 9 
 
 60 8 
 
 75 10 
 
 75 10 
 
 90 10 
 
 64 7 
 
 52 6 
 
 68 8 
 
 S3 7 
 
 68 8 
 
 70 7 
 
 72 9 
 
 60 8 
 
 80 8 
 
 88 8 
 
 90 10 
 
 17,160 
 
 16,673 
 
 17.403 
 
 17,316 
 
 17,400 
 
 15,600 
 
 12,480 
 
 15,600 
 
 15,600 
 
 17,160 
 
 18,954 
 
 50 
 
 44| 
 
 ,52* 
 
 484 
 
 60 
 
 60 
 
 60 
 
 60 
 
 60 
 
 60 
 
 44^ 
 
506 
 
 THB orJiKATIVE MECHANIC 
 
 A Table of Trains for Watches continued. 
 
 15 Teeth in the Balance-ivheel. 
 
 Second wheel 
 
 48 6 
 
 Third wheel pinion. . . . 
 
 48 6 
 
 48 6 
 
 54 6 
 
 54 6 
 
 54 6 
 
 Third 
 
 wheel 
 
 45 6 
 
 Contrate pinion 
 
 
 45 6 
 
 45 6 
 
 48 6 
 
 48 6 
 
 48 C ^ 
 
 Contrate wheel 54 6 
 
 Balance 
 
 pinion , 
 
 
 58 6 
 
 60 6 
 
 46 6 
 
 48 6 
 
 64 8 
 
 Beats 16,200 in an 
 
 hour . . 
 
 
 17,400 
 
 18,000 
 
 16,560 
 
 17,280 
 
 17,280 
 
 Seconds 60, 
 
 in which the 4th wheel revolves 
 
 60 
 
 60 
 
 50 
 
 50 
 
 50 
 
 54 6 
 
 56 7 
 
 56 7 
 
 56 7 
 
 56 6 
 
 56 7 
 
 58 6 
 
 58 6 
 
 60 8 
 
 60 8 
 
 60 8 
 
 50 6 
 
 45 6 
 
 45 6 
 
 45 6 
 
 48 6 
 
 60 8 
 
 48 6 
 
 50 8 
 
 48 6 
 
 48 6 
 
 56 7 
 
 48 6 
 
 56 6 
 
 58 6 
 
 60 6 
 
 46 6 
 
 60 6 
 
 46 6 
 
 58 6 
 
 58 6 
 
 60 6 
 
 48 6 
 
 18,000 
 
 16,800 
 
 17,400 
 
 18,000 
 
 17,173 
 
 18,000 
 
 17,786 
 
 17,520 
 
 17,400 
 
 18,000 
 
 14,400 
 
 48 
 
 60 
 
 60 
 
 60 
 
 48 
 
 60 
 
 46f 
 
 59i 
 
 60 
 
 60 
 
 60 
 
 60 8 
 
 60 7 
 
 60 8 
 
 60 8 
 
 60 8 
 
 60 6 
 
 60 6 
 
 60 6 
 
 60 6 
 
 60 10 
 
 60 G 
 
 56 7 
 
 56 7 
 
 56 7 
 
 56 7 
 
 56 7 
 
 60 8 
 
 60 10 
 
 60 8 
 
 60 10 
 
 60 6 
 
 60 10 
 
 56 7 
 
 58 7 
 
 58 6 
 
 60 6 
 
 60 7 
 
 48 6 
 
 48 6 
 
 56 7 
 
 58 6 
 
 60 6 
 
 64 8 
 
 14.400 
 
 17,044 
 
 17,400 
 
 18,000 
 
 15, .386 
 
 18,000 
 
 14,400 
 
 18,000 
 
 17,400 
 
 18,000 
 
 14,400 
 
 60 
 
 52§ 
 
 60 
 
 60 
 
 60 
 
 48 
 
 60 
 
 48 
 
 60 
 
 60 
 
 60 
 
 60 8 
 
 60 8 
 
 62 8 
 
 63 7 
 
 63 7 
 
 64 8 
 
 64 8 
 
 64 8 
 
 64 6 
 
 65 7 
 
 70 6 
 
 64 8 
 
 64 8 
 
 60 8 
 
 54 7 
 
 56 7 
 
 45 6 
 
 60 8 
 
 60 8 
 
 60 10 
 
 56 7 
 
 60 10 
 
 66 7 
 
 70 7 
 
 60 6 
 
 50 6 
 
 56 7 
 
 56 6 
 
 58 6 
 
 60 6 
 
 70 8 
 
 56 7 
 
 48 6 
 
 16,971 
 
 18,000 
 
 17,437 
 
 17,356 
 
 17,280 
 
 16,800 
 
 17,400 
 
 18,000 
 
 16,800 
 
 17,828 
 
 16,800 
 
 60 
 
 60 
 
 61| 
 
 51f 
 
 50 
 
 60 
 
 60 
 
 60 
 
 56^ 
 
 48| 
 
 51 | 
 
 70 7 
 
 70 8 
 
 70 8 
 
 70 10 
 
 72 6 
 
 72 8 
 
 72 8 
 
 72 8 
 
 72 8 
 
 75 8 
 
 81 9 
 
 60 10 
 
 64 8 
 
 64 8 
 
 65 8 
 
 60 10 
 
 64 8 
 
 64 8 
 
 64 8 
 
 65 8 
 
 64 8 
 
 72 9 
 
 70 7 
 
 50 6 
 
 58 7 
 
 60 6 
 
 48 6 
 
 50 6 
 
 54 7 
 
 64 8 
 
 64 8 
 
 64 8 
 
 72 9 
 
 i 18,000 
 
 17,500 
 
 17,400 
 
 17,062 
 
 17,280 
 
 18,000 
 
 16,662 
 
 17,280 
 
 17,550 
 
 18,000 
 
 17,280 
 
 60 
 
 51i 
 
 51i 
 
 56| 
 
 50 
 
 50 
 
 50 
 
 50 
 
 49 
 
 48 
 
 50 
 
 17 Teeth in the Balance-icheel. 
 
 Second wheel 
 
 48 6 
 
 Third wheel pinion .... 
 
 56 7 
 
 Third wheel 
 
 45 6 
 
 Contrate 
 
 pinion 
 
 
 45 6 
 
 Contrate wheel 50 6 
 
 Bal ance 
 
 pinion 
 
 
 53 6 
 
 Beats 17,000 in an 
 
 hour . . . 
 
 
 
 18,020 
 
 Seconds 60, 
 
 in which the 4th wheel revolves 
 
 60 
 
 o.w. 
 
 S.W. P. ' 
 
 r. N. s. 
 
 G. w. ; 
 
 s. vv. P. 
 
 T. N, S. 
 
 G. W. 
 
 48 
 
 10 
 
 
 60 
 
 10 
 
 5 
 
 55 
 
 50 
 
 10 
 
 6 
 
 62 
 
 10 
 
 4| 
 
 56 
 
 52 
 
 10 
 
 H 
 
 64 
 
 10 
 
 
 58 
 
 54 
 
 10 
 
 
 48 
 
 12 
 
 
 60 
 
 55 
 
 10 
 
 5 6 
 
 50 
 
 12 
 
 '71 
 
 * 
 
 62 
 
 56 
 
 
 
 52 
 
 12 
 
 ^>’41 
 
 64 
 
 58 
 
 10 
 
 
 54 
 
 12 
 
 6| 
 
 
 60 8 
 
 64 8 
 
 56 7 
 
 60 8 
 
 52 6 
 
 60 7 
 
 17,828 
 
 17,485 
 
 60 
 
 60 
 
 s. w. p. 
 
 T.N.S. 
 
 12 
 
 
 12 
 
 
 12 
 
 
 12 
 
 6 
 
 12 
 
 
 12 
 
 
 If we divide double the product of all the four wheels by the product of 
 all the three pinions, the quotient will be the number of beats, as given in 
 any of the trains contained in this table ; also, if we take the second and 
 third w'heels, and their pinions respectively, as a compound fraction of an 
 hour, they will give the seconds in which the contrate-wheel, attached to the 
 latter pinion, will revolve ; thus, of^’^ of ^ of 60*"= or 60*, which numbers 
 
AND MACHINIST. 
 
 507 
 
 are consequently proper for a watch that indicates the seconds ; and if the 
 beats be 18,000, or 14,400, there wall be five or four beats respectively in 
 a second, which are the best trains for measuring fractional parts of a second. 
 
 CHRONOMETERS. 
 
 Chronometers differ from an ordinary watch principally in 
 the escapement and balance. These machines deserve more 
 than usual attention, as well from their practical utility in 
 navigation, as from the principles on which they are con- 
 structed, in which the irregular f^srces both of impulse and 
 resistance are greatly diminished by the exactness of form 
 and dimension. 
 
 In the reign of queen Anne, the British parliament passed 
 an act, offering a reward of 10,000/. for any method of 
 determining the longitude within the accuracy of one degree 
 of a great circle ; of 1 5,000/. within the limit of forty 
 geographical miles ; and of 20,000/. within the limit of thirty 
 such miles, or half of a degree ; provided such method should 
 extend more than eighty miles from the coast. The hope 
 of obtaining this reward stimulated a watch-maker named 
 Harrison to be indefatigable in his endeavours to effect the 
 required improvement, which eventually led him to apply 
 the principle of the apposite expansions of different metals 
 to a watch to effect a self-regulating curb, for limiting the 
 effective length of the spiral pendulum-spring to correspond 
 to the successive changes of heat and cold, w'hich changes 
 were now known to alter the force of this spring, and the 
 momentum of the balance. 
 
 After Harrison had by his industry and perseverance ob- 
 tained the large reward, the act was repealed, and another 
 substituted, offering separate rewards to any person who 
 should invent a practicable method of determining, within 
 circumscribed limits, the longitude of a ship at sea ; for a 
 time-keeper, the reward held forth to the public is 5,000/. 
 for determining the longitude to or within one degree 5 
 7,500/. for determining the same to forty geographical miles ; 
 and 10,000/. for a determination at or within half a degree. 
 This act, notwithstanding its abridged limits and diminished 
 reward, has produced several candidates ; of whom Mudge, 
 the two Arnolds, and Earnshaw, have had their labours 
 crowned with partial success. 
 
 Although, in respect to Mudge’s time-keeper, great ex- 
 pectations were at first raised, it has, from the complexity 
 of the machinery, and consequent expense attendant upon 
 making it, gradually fallen into disrepute, and is now seldom 
 or ever made. Such of our readers who wish to see its 
 
508 
 
 THK orjiRATIVE MECHANIC 
 
 manner of construction and performance, we must refer to 
 
 The Description of Mr. Mudge's Time-keeper/’ published 
 in 1709, by Thomas Mudge, jun. 
 
 The chronometer we purpose to lay before our readers is 
 that constructed by Mr. Earnshaw, as we are strongly dis- 
 posed to conclude, from various documents we have seen, 
 and from the similarity so evident in the construction of the 
 escapement, that Mr. Arnold derived the knowledge of his 
 principle from Mr. EarnsK>;w. 
 
 In Mr.Earnshaw’s chronometer the escapement is detached, 
 which is the best for the equal measurement of time, because 
 the vibrations of the balance are free from the friction of the 
 wheels, excepting about one-twelfth part of the circle, while 
 the scape-wheel is acting on the pallet to keep up the motion 
 of the balance, which is done with considerably more power 
 and less friction than by any other escapement, as it receives 
 but one blow from the wheel, whilst other escapements receive 
 two ; it has also an equal advantage of the same quickness of 
 train, and when the impulse is given to the balance by the 
 wheel, it is given in a similar direction, and not in opposition, 
 as most escapements are which produce a recoil. 
 
 The pivots of the balance-axis should be the 
 size of the verge-pivots of a good sized pocket- 
 w'atch, and of the annexed shape, which v/ill greatly 
 add to their strength, the extreme end, or acting 
 part, only being straight; the jewel-hole should be 
 as shallow as possible, so as not to endanger cutting 
 the pivot, and the part of the action of the hole made quite 
 back, with only a very shallow chamber behind to retain the 
 oil ; deep holes are very bad, for when the oil becomes 
 glutinous, it will make the pivots stick, so as to prevent the 
 balance from its usual vibration. The pallet should be half 
 the diameter of the wheel, or a little larger, for if smaller, or 
 one-fourth the diameter, as is the case in Arnold’s, the 
 wheel will have too much action on it, which will increase 
 friction most considerably, and likewise cause the balance to 
 swing so much farther to clear the wheel ; consequently, 
 a check in the motion of the balance may stop the watch, 
 and cause time-keepers so constructed to stop. The face of 
 ^he pallet should run in a line of equal distance between the 
 centre of the pallet and its extremity, and not in a right line 
 to its centre, as this causes an increase of friction, and a loss 
 of that power which is obtained by the wheel, acting on the 
 ^'xtremity of the pallet. The scape-wheel teeth should form 
 the same direction as the face of the pallet, under-cut for 
 
AND MACHINIST. 
 
 509 
 
 the purpose of avoiding friction, and maintaining the pov/er, 
 and for safe unlocking. The points of the wheel-teeth must 
 not be rounded off, but left as sharp as possible. The pivots 
 of the scape-wheel are to be a very little larger than the 
 balance-pivots. 
 
 The wheel is locked by a spring, instead of a detent with 
 
 E ivots, as the French have made them ; for those pivots must 
 ave oil, and when the oil thickens, the spring of the pivot- 
 detents become so affected by it, as to prevent the detent 
 from falling into the wheel quick enough, which causes irre- 
 gular time, and ultimately a stoppage of the watch. 
 
 When the spring is planted on the side of the wheel, the 
 part on which the wheel rests should be a little short of a 
 right angle, so that the wheel may have a tendency to draw 
 the spring into it ; for if sloped the other way, or beyond 
 a right angle, it will have a tendency to push the spring out, 
 in which case the wheel will have liberty to run. The wheel 
 should take no more hold on the spring than just sufficient 
 to stop it, otherwise the friction will be increased. The 
 small return-spring should be as thin as possible at the end 
 fastened to the other spring, but at the outer end a little 
 thicker ; the spring should be planted down as close to the 
 wheel as to be just free of it : the discharging pallet about 
 one-third, or near one-half the size of the large or main 
 pallet, the face of it in a right line to the centre, the back of 
 it a little rounding off from the centre. Great care must 
 be used, in taking off the edges of this discharging piece to 
 make it round, to prevent cutting the spring, nor can it be 
 made too thin, provided it does not cut ; the end of it nearest 
 the balance should be a little more out from the centre of the 
 balance-axis than the lower part of it towards the potence, 
 for counteracting the natural tendency of the spring down- 
 wards from the pressure of the scape-wheel ; and that part 
 of the spring on which the wheel rests should be sloped a 
 little down, to give the wheel a tendency to force it up, to 
 counteract the natural inclination which the wheel has to 
 draw it down by its pressure on it. 
 
 The balance is to be made of the best steel, and turned from 
 its own centre to the proper size, and then put into a crucible 
 with as much of the best brass as will, when melted, cover it. 
 The brass will adhere to the steel, and when set, is to be 
 turned to its proper thickness, and hollowed out, so as to 
 leave the steel rim about the thickness of a repeating-spring 
 to a small sized repeating-watch. The brass is to be turned 
 to near twice or three times the thickness of the steel ; cross 
 
510 
 
 THE OPERATIVE MECHANIC 
 
 it out with only one arm straight across the centre, and at 
 each end of the arm fix two screws, opposite to each other, 
 through the rim of the balance, to regulate the watch to time. 
 The diameter of the heads of these screws must be about 
 equal to the thickness of the balance, a little more or less is 
 not material. The compensation-weights should be made of 
 the best brass, and well hammered, and a groove turned to let 
 the rim of the balance into it ; this should be cut into four- 
 teen equal parts, which will leave seven pair of pieces of 
 equal size and weight, one of which pair, being screwed on 
 the rim of the balance at equal distances, will produce an 
 equilibrium. In making balances, great care must be taken 
 that they get no bruises or bendings; for if a bruise be made on 
 one side so as to indent the metal, that part will be less affected 
 by the atmospheric agency of heat and cold than those parts 
 whose pores have not been closed by the same violence. 
 
 Balances are likewise spoiled by bending the compensation- 
 pieces, as bending cracks and destroys the compact body of 
 the metal. The soldering up those cracks with a metal very 
 different in expansion to the metal cracked is hurtful, as it is 
 not then possible to bend the compensation-pieces into a 
 true circle, in which case they form so many parts of different 
 circles, that nothing regular can be produced. 
 
 To adjust the balance in heat and cold, put the watch into 
 about 85 or 90 degrees of heat by the common thermometer, 
 mark down exactly how much it gains or loses in twelve 
 hours, then put it into as severe a cold as you can get for 
 twelve hours ; and if it gain one minute more in twelve hours 
 in cold than in heat, move the compensation-weights farther 
 from the arm of the balance about one-eighth of an inch ; 
 and if it gain one minute more in twelve hours in heat than 
 in cold, move the weights one-eighth of an inch nearer to the 
 arm of the balance, and so on in like proportion, trying it 
 again and again, till you find the watch go the same in what- 
 ever change of heat or cold you put it in. 
 
 Mr. Earnshaw has found out a method of obviating the 
 difficulties attendant in making time-keepers go nearly the 
 same in whatever position they might be put. It merely 
 consists in having the balance-spring well and properly made ; 
 but if the spring be made as hereafter described, it only re- 
 quires that the balance should be of equal weight, and it will 
 go, within a few seconds per day, in all positions alike ; and 
 if it vibrate not more than 1^ circle, will, by applying a 
 small weight to that part of the balance which is downwards 
 when in the position that it loses most, correct it with gi*eat 
 
AND MACHINIST. 
 
 511 
 
 accuracy. If it vibrate more than 1 J circle, it will require 
 the weight to be above, instead of below ; and after the watch 
 has been going a few months, and its vibrations shorten to 
 1| circle, it will go worse and worse by reason of the weight 
 being in the wrong place ; therefore, to avoid this evil, it is 
 absolutely necessary to confine the vibrations to IJ circle, 
 which will produce the most steady performance. 
 
 The greatest difficulty with which Mr. Earnshaw had to 
 contend in the construction of his chronometers was, to find 
 out the invisihle properties of that apparent simple part of the 
 machine, called the balance-spring. He found, in reasoning 
 on bodies, that watch-springs, when kept constantly in mo- 
 tion, relax and tire like the human frame. In proof of this, 
 let a watch, that has been going a few months, go down ; let 
 it remain down for a week or two, and then set it going, when 
 it will, if it be a good time-keeper, and not affected by the 
 weather, go some few seconds per day faster than it did when 
 it was let down ; but it will again lose its quickness in a 
 gradual manner, gaining less and less till it comes to its 
 former rate. Finding, therefore, that isochronal springs 
 would not do, and having made s]3rings of such shape as 
 w’ould render long and short vibrations equal in time, and 
 which constantly lost the longer the watch went, Mr. Earn- 
 shaw made them of such shape as to gain in the short 
 vibrations about five or six seconds per day more than the 
 long ones, which quantity could only be found by long expe- 
 rience ; an^ the way he adopted to prove this, was to try the 
 rate of the watch with the balance vibrating about one-third 
 of a circle, then tried its rate vibrating IJ circle; and if the 
 short vibrations went slow^er than the long ones, he found 
 that the watch would lose in its rate ; and if equal, it would 
 likewise lose, but that only from relaxation ; he found also, 
 if it gain in the short vibrations more than five or six seconds 
 in twenty-four hours, it will in the long rtin gain on its rate ; 
 but if not more than that quantity, and the time-keeper is 
 perfect in heat and cold in every other part, the above pro- 
 perties will render it deserving the name of a perfect time- 
 keeper. Mr. Earnshaw found the common relaxation of 
 balance- springs to be about five or six seconds per day on 
 their rates in the course of a year ; therefore, if the short 
 vibrations are made by the shape of the spring to go about 
 that quantity faster than the long ones, and as the spring 
 relaxes in going by time, so the watch accumulates in dirt 
 and thickening of the oil, which shortens the vibrations, the 
 
512 
 
 THE OPERATIVE MECHANIC 
 
 *5hort ones then being quicker, compensated for the evil of 
 relaxation of the balance-spring. 
 
 Having thus given our readers Mr. Earnshavv's prefatory 
 observations to the Board of Longitude, we shall, in the next 
 place, proceed to give a general description of the dilfeient 
 parts of his chronometer. 
 
 Fig. 510 represents the time-keeper put together. 
 
 Fig. 511, the pillar-plate from which the calliper may be taken; a, the 
 height of the pillars. 
 
 Fig. 512, the barrel and main-spring; 5, side view of the barrel. 
 
 Fig. 513, the fusee and great wheel, with ratchet to keep it going whilst 
 winding up ; c, side view of fusee. 
 
 Fig. 514, second wheel and pinion; d, side view of second wheel. 
 
 Fig. 515, third wheel and pinion ; e, side view of it. 
 
 Fig. 51 6, fourth wheel and pinion ; f, side view of it. 
 
 Fig. 517 represents the upper plate, with the escapement on it, from 
 which the calliper may be taken. In this figure the draftsman has not 
 placed the pallet near enough the wheel ; but this is of no consequence, as 
 a proper and exact draft of the escapement on a much larger scale is given 
 in fig. 522 ; the escapement, therefore, is to be understood from that figure ; 
 this only show's the sizes of the wheels. 
 
 Fig. 518 represents a side view of the scape-spring which locks the wheel. 
 
 Fig. 519, one of the brass weights to be fixed on the rim of the balance 
 for the compensation for heat and cold; the groove cut in it to receive 
 the rim of the balance. The rim of the balance is cut through in two places 
 in opposite directions, as in fig. 510, and two of these w'eights are to be 
 placed on the balance-rim, at equal distances, as there represented, and 
 fastened by the screw as at /^. These weights are to be moved backwards 
 or forwards on the rim of the balance, to make the watch go faster or 
 slower in heat or in cold, as by trial may be found necessary. 
 
 Fig. 520 is a side view of said brass weights ; the groove to receive 
 the rim of the balance ; its depth shows the breadth for balance-ring. 
 
 Fig. 521, the cylindrical balance-spring. The only advantage attending 
 the cylindrical shape is, that it is rather easier made, being a saving of about 
 one hour of time ; for if the real body or form of the spring be like the shape 
 of the stem of a feather, or common writing quill, it is of no consequence 
 whether it be turned into a spiral or cylindrical figure. 
 
 The model, from which the four following figures were taken, contains, 
 besides the parts necessary to explain the nature of the escapement, a box 
 enclosing a spring, which, when wound up, communicates, by means of 
 some more wheels, a force to the balance-wheel sufficient, when the balance 
 is put in motion, to keep it in action for some time. These wheels are 
 contained between two brass plates, fastened together by four upright pil- 
 lars. The uppermost of these plates is that which is represented in fig. 522, 
 where P Q R S are the four screws that take into the heads of the four pillars 
 above-mentioned, and connect it to the remaining part of the model. The 
 plate P Q R S contains, however, the whole of the parts necessary for the 
 present purpose. The side of this plate represented to view, is the under- 
 most when fixed in the model ; so that the figure represents this plate as 
 taken off, with the side next to the balance laid upon a table, and the eye ii 
 supposed to be placed perpendicularly over it. 
 
 In the plate PQKS is an opening, or a piece taken out, represented hy 
 
iTetU AStodcUy sc 3Sz Strand. 
 
1 
 
 
AND MACHINIST. 
 
 513 
 
 T U W X Y Z. In this opening the balance-wheel A B C D, pallet M S K, 
 and part of the balance TJ V, are seen. The balance-wheel is supported by 
 two pieces of brass, O N H, O I ; the piece O N II is screwed to the side of 
 the plate nearest to view by a strong screw, V, and made firm by small 
 pins, represented by ttit tt tt tt tt ; these pins are called steady -pins ; they 
 are rivetted fast into the supporting-piece O H, and take into holes in the 
 plate P Q R S, made exactly to fit them. The part O N of this supporting- 
 piece is supposed to be raised above the part 0 II by a joint or bend at N : 
 the otlier supporting-piece O I is fastened to the opposite side of the plate ; 
 and between these two pieces the balance-wheel turns freely and steadily 
 in the direction of the letters A BC D. The small wheel M S K is called 
 the large pallet ; it is a cylindrical piece of steel, having a notch or piece 
 cut out of it at I h I ; against the side of this notch is a square, flat piece of 
 ruby, or any hard stone, h I, ground and polished very smooth, and fixed 
 into the pallet. The cylinder is so placed, with respect to the -balance- 
 wheel, that it may not be more than just clear of two adjoining teeth. E F 
 is a long, thin spring, which is made fast at one end, by being pinned into 
 a stud G, and made to bear gently against the head of an adjusting screw, 
 m ; the otlier end is bent a little in the form of a hook ; to this spring there 
 is fixed anotlier very slender spring at 7, which projects to a small distance 
 beyond it. This small spring lies on the side of the thick spring nearest to 
 the balance-wlieel. The adjusting screw m takes into a small brass cock at 
 ap, which is screwed fast to the upper plate by a strong screw. Upon the 
 spring E F there is fixed a semi-cylindrical pin, which stands up perpen- 
 dicularly upon it, and of a sufficient length to fall between the teeth of the 
 balance-wheel A B CD. This pin is called the locking-pallet, and is placed 
 on the opposite side of the spring represented to view. Through the centre 
 of the cylindrical pallet M S K, a strong steel axis passes, called the verge ; 
 the pallet is made fast to this axis, which also passes through the centre of 
 the balance, and is made fast to it ; it has two fine pivots at its extremities, 
 upon which it turns very freely, between two firm supporting pieces of 
 brass, screw'ed firmly, and made as permanent as possible, by steady-pins, 
 to the principal plate. A little above the cylindrical pallet M S K, is fixed 
 a small cylindrical piece of steel, i w, having a small part projecting out at i, 
 through which the verge also passes ; this is called the lifting-pallet, and is 
 from one-third to half the diameter of the large pallet ; it fixes upon the verge 
 like a collar, and is made fast by a twist, so as to be set in any position 
 with respect to the large pallet M S K. The end E G of the long spring 
 E F being made very slender, if a small force be applied at the point 0 to 
 press that end out from the wheel A B C D, it yields easily in that dire(i 
 tion, turning, as it were, upon a centre at G ; it is also made to slide in a 
 groove made in this stud, in such a manner that the end 0 may be placed at 
 any required distance from the centre of the verge. 
 
 Having described the several parts as they appear in the figure, we next 
 come to their situation or connection with respect to each other. Let the 
 long spring EF be supposed to be so placed, that the end of the slender 
 spring y i may project a little way over the point of the lifting-pallet i n, 
 but not so close but that the point of the pallet may pass by the hooked end 
 of the spring EF without touching it; the head of the adjusting-screw m is 
 ajso supposed to bear gently on the inner side of the said spring E F, or 
 that nearest to the wheel, and at the same time the locking-pallet is so 
 placed, that one of the teeth, D, of the balance-wheel, may just take hold 
 of it. This pallet is not visible in its proper place in the figure, being 
 covered from sight by the screw ni, and part of the spring E F ; its. position 
 is therefore represented by the dot on the opposite side of the wheel, 
 
514 
 
 TflK OPERATIVE MECHANIC 
 
 having the tooth A just bearing up against it. From the above description 
 of the several parts of the escapement, and their connection with each other 
 it will be easy to see the mode of its action, which is as follows : 
 
 A force being supposed to be applied to the balance- wheel, so as to cause 
 it to move round in the direction of the letters A B C D, one of the teeth, as 
 D, will come against the locking-pallet (as represented at A, and the lockino-- 
 pallet by k.) The wheel is then said to be locked, being prevented from 
 being moved forward by this pin. Let the balance be now supposed to 
 rest in its quiescent position, and it will have the situation represented in 
 the figure ; the lifting-point i of the pallet i n will be just clear of the pro- 
 jecting end of the slender spring, the face, h I, of the large pallet M S K will 
 fall a little below the point of the tooth B, and the balance, having its spiral 
 or helical (meaning cylindrical) spring applied to it, remains perfectly at 
 rest in this position. Now, as the balance, and the two pallets M S K and 
 i n, are fixed to the verge, it is plain they must all move together ; let, there- 
 fore, the balance be carried a little way round in the direction of the letters 
 M S K ; by this motion, the end i of the lifting-pallet i n will be brought to 
 press up against the projecting end of the slender spring, and as this spring 
 is fixed on the side of the spring E F, nearest to the balance-wheel, the 
 point i will press the two springs together out of the balance-wheel ; then, 
 as only the point of the tooth D (see its position at k) touches the locking- 
 pallet when the spring EF was at rest against the head of the screw m, it 
 will, by the spring being pressed out from the tooth, have slipped oft’; (for 
 the locking-pallet, which was before supposed at k, will now be at a, clear 
 of the tooth A of the balance-wheel ;) the wheel being now at liberty, will 
 move round by the force supposed to be applied to it ; but as the point i of 
 the lifting-pallet moves on and presses out the spring, the point, I, of the 
 large pallet approaches towards the point of the tooth B of the balance- 
 wheel, so that when the spring E F is sufficiently pushed out to unlock the 
 wheel, the point I of the large pallet will be got to d, and in this position 
 the point of the tooth B of the balance-wheel will fall upon it, at the same 
 time the point of the tooth D has just dropped off from the locking-pallet 
 m ; the force of the wheel, being by this means applied to the top of the 
 pallet h I, gives an increased momentum to the balance, and assists it in its 
 motion in the same direction, and by the continued motion of the large 
 pallet in the direction M S K, the point of the tooth B, which keeps pressing 
 and urging it forward, moves up towards the bottom of the face of the pallet 
 towards h, until the plain fiat surfaces of the tooth and pallet come into 
 contact ; by this time the end o of the slender spring has dropped off from 
 the point i of the lifting-pallet, and the two springs have returned again 
 into their quiescent position, the spring E F gently bearing against the head 
 of the adjusting screw, m, and the locking-pallet, in a position to receive the 
 next tooth, C, of the balance-wheel. When the two surfaces of the tooth 
 and pallet are thus in contact, the greatest force of the wheel is exerted upon 
 the pallet, and of course upon the balance moving with it. The tooth still 
 pressing against the face of the pallet, and the pallet moving in the direction 
 M S K, it at ,last drops off, leaving the balance at perfect liberty to move 
 on in the same direction in which it was going. Just as the point of the 
 tooth B, which has been pressing the large pallet round, is ready to leave 
 it, the next tooth, C, of the wheel is almost in contact with the locking- 
 pallet m, so that the instant the tooth B drops off, the wheel is again locked, 
 and the action of that tooth on the balance is finished. As the balance 
 moves with the greatest freedom upon its pivots, the force of the tooth has 
 given it a considerable velocity, so that the balance still keeps moving on 
 in the same direction, after the pressure of the tooth is removed by slipping 
 
AND MACHINIST. 
 
 515 
 
 off from the pallet, until the force of the pendulum-spring, (which is not 
 represented in the figure,) being continually increased by being wound up, 
 overcomes the momentum of the balance, which for an instant of time is 
 then stationary, but immediately returns by the action of the pendulum- 
 spring, which exerts a considerable force upon it in unwinding itself. As 
 the balance returns, the point i, of the lifting-pallet i n, passes by the ends 
 of two springs, EF and Y O, and, in passing by, pushes the projecting end o 
 of the slender spring in towards the balance-wheel, until it has passed it ; 
 after this, the projecting end o again returns, and applies itself close to the 
 hooked end of the spring E F as before. The spring yo is made so slender, 
 that it gives but little resistance to the balance, during the time the point i 
 of the lifting-pallet is passing it, and of course causes but little, if any, de- 
 crease in its momentum. During the time the point i of the lifting-pallet 
 is pressing in the small spring y o, the long spring E F remains steadily 
 bearing against the head of the adjusting screw m, as the hooked end at o 
 just lets the end of the lifting-pallet pass by without touching it. As the 
 spring has now been continually acting upon the balance, from the extremity 
 of its vibration in the direction M S K, it has given it the greatest velocity 
 when the point i of the lifting-pallet is passing the end o of the slender 
 spring; for at this instant the spring which was wound up by the contrary 
 direction of the balance, is now unwound again, or in the same state as it 
 was in its quiescent position at first, and of course has no effect at all upon 
 the balance in either direction ; but the balance, having now all the velocity 
 it would acquire from the unwinding the spring, goes on in the direction 
 S M K until the force of this spring again stops it, and brings it back again, 
 moving in the same direction as at first, with a considerable velocity. By 
 this return of the balance, the point i of the lifting-pallet comes up again to 
 the projecting end o of the slender spring, pushes back the long spring E F, 
 and unlocks the wheel ; and another tooth falling upon the face of the pallet 
 A Z, gives fresh energy to the balance ; and thus the action is carried on as 
 before. 
 
 ESCAPEMENT, OR ’SCAPEMENT. 
 
 The motions of a clock or watch are regulated by a pen- 
 dulum or balance, which serves as a check, without which, 
 the wheels impelled by the weight in the clock, or spring in 
 the watch, would run round with a rapidly accelerating 
 motion, till this should be rendered uniform by friction, and 
 the resistance of the air ; if, however, a pendulum or balance 
 be put in the way of this motion, in such manner that only 
 one tooth of a wheel can pass, the revolutions of the wheel 
 will depend on the vibration of the pendulum or balance. 
 
 We know that the motion of a pendulum or balance is 
 alternate, while the pressure of the wheels is constantly 
 exerted in the same direction. Hence it is evident that some 
 means must be employed to accommodate these different 
 motions to each other. Now, when a tooth of the wheel has 
 given the pendulum or balance a motion in one direction, it 
 must quit it, that the pendulum or balance may receive an 
 impulsion in the opposite direction. This escaping of the 
 tooth has given rise to the term escapement 
 
 2 L 2 
 
516 
 
 THE OPERATIVE MECHANIC 
 
 The ordinary ’scapenient is extremely simple, and may be thus illustrated. 
 Let x'y, fig. 523, represent a horizontal axis, to which the pendulum is 
 attached by a slender rod. This axis has two leaves, c and rf, one near 
 each end, and not in the same plane, but so that when the pendulum hangs 
 perpendicularly at rest, c spreads a few degrees to the right, and d as much 
 to the left. These are called the pallets. Let afb represent a wheel, 
 turning on a perpendicular axis, e o, in the order af eh. The teeth of this 
 wheel are in the form of those of a saw, leaning .forward in the direction of 
 the rim’s motion. This wheel is usually called the crown-ivheel, or in 
 watches the halance-wheel. It in general contains an odd number of teeth. 
 In the figure the pendulum is represented at the extremity of its excursion 
 towards the right, the tooth a having just escaped from the pallet e, and b 
 having just dropped on d. 
 
 Now it is evident, that while the pendulum is moving to the left, in the 
 arc jt) g, the tooth h still presses on the pallet d, and thus accelerates the 
 pendulum, both in its descent along p h, and its ascent up kg, and that 
 when d, by turning round the axis x y, raises its point above the plane of 
 the wheel, the tooth b escapes from it, and i drops on c, now nearly perpen- 
 dicular. Thus c is pressed to the right, and tlie motion of the pendulum 
 along gp is accelerated. Again, while the pendulum hangs perpendicularly 
 in the line h, the tooth b, by pressing on d, will force the pendulum 
 to the left, in proportion to its lightness, and if it be not too heavy, will 
 force it so far from the perpendicular, that b will escape, and i will catch 
 on c, and force the pendulum back to p, when the same motion will be 
 repeated. This effect will be the more remarkable if the rod of the pen- 
 dulum be continued through .r y, and have a ball q, on the other end, to 
 balance p. 
 
 When b escapes from d, the balls are moving with a certain velocity and 
 momentum, and in this condition the balance is checked when i catches 
 on c. It is not, however, instantly stopped, but continues to move a little 
 to the left, and i is forced a little backward by the pallet c. It cannot make 
 its escape over the top of the tooth i, as all the momentum of the balance 
 was generated by the force of b, and i is of equal power. Besides, when 
 i catches on c, and the motion of c, to the left, continues, the lower point 
 of c is applied to the face of i, which now acts on the balance by a long 
 lever, and soon stops its motion in that direction, and, continuing to press 
 on c, urges the balance in the opposite direction. In this, it is evident that 
 the motion of the wheel is hobbling and unequal, by which this escapement 
 has received the appellation of the recoiling \scapement. 
 
 In considering the utility of the following improved ’scape- 
 ment for clocks, we must keep in mind the following propo- 
 sition, which, after the above illustration, scarcely requires 
 any proof. It is, that the natural vibrations of a pendulum 
 are isochronous, or are performed in equal times. The great 
 object of the ^scapernent is to preserve this isochronous 
 motion of the pendulum. 
 
 As the defect of the recoiling ’scapenient was long ap- 
 parent, several ingenious artists attempted to substitute in 
 its place a ’scapenient that should produce a more regular 
 and uniform motion. Of these, the ’scapenient contrived by 
 Mr. Cuinming appears to be one of the most ingenious in its 
 construction, and most perfect in its operation. The follow- 
 
JESCAFJEMJENTS 
 
 Tl.77. 
 

AND MACHINIST. 
 
 ^>17 
 
 lug construction is similar to that of Mr. Gumming, but 
 rendered rather less complex for the purpose of shortening 
 the description. 
 
 Let ABC, fig. 524, represent a portion of the swing-wheel, of which O 
 is the centre, and A one of the teeth, and Z the centre of the crutch, the 
 pallets, and pendulum. The crutch is represented of the form of the letter 
 A, having in the circular cross-piece a slit i k, which is also circular, Z being 
 the centre. The arm Z F forms the first detent, and the tooth A is repre- 
 sented as locked on it at F. D is the first pallet on the end of the arm Z d, 
 movable round the same centre with the detents, but independent of them. 
 The arm, d e, to which the pallet D is attached, lies wholly behind the arm Z F 
 of the detent, being fixed to a round piece of brass, efg, having pivots 
 turning concentric with the axis of the pendulum. To the same piece of 
 brass is fixed the horizontal arm c H, carrying at its extremity the ball H, 
 of such size that the action of the tooth A on the pallet D is just able 
 raise it up to the position represented. Z P/r represents the fork, or pen- 
 dulum-rod, behind both detent and pallet. A pin p projects forward, 
 coming through the slit i k, without touching either margin of it. Attached 
 to the fork is the arm m n, of such length that, when the pendulum-red is 
 perpendicular, the angular distance of nq from the rod e q H is just equal 
 to the angular distance of the left side of the pin p from the left end i of the 
 slit i k. 
 
 Now the natural position of the pallet D is at S, represented by the dotted 
 lines, resting on the back of the detent F. It is naturally brought into this 
 position by its own weight, and still more by the w'eight of the ball II. 
 The pallet D, being set on the foreside of the arm at Z, comes into the same 
 plane with the detent F and the swing-wheel, though represented in the 
 figure in a different position. The tooth C of the wheel is supposed to have 
 escaped from the second pallet, on which the tooth A immediately seizes 
 the pallet 1), situated at 5, forces it out, and then rests on the detent F, the 
 pallet D leaning on the tip of the tooth. After the escape of C, the pen- 
 dulum, moving down the arch of semi-vibration, is represented as having 
 attained the vertical position. Proceeding still to the left, the pin p reaches 
 the extremity i of the slit i k; and, at the same instant, the arm n touches 
 the rod e II in q. The pendulum proceeding a hair’s-breadth further, with- 
 draws the detent F from the tooth, which now pushes off the detent, by 
 actin<r on the inclining face of it. 
 
 The wheel being now unlocked, the tooth, following C on the other side, 
 acts on its pallet, pushes it off, and rests on its detent, which has been 
 rapidly brought into a proper position by the action of A on the inclined 
 face of F, By a similar action of C on its detent at the moment of escape, 
 F was brought into a position proper for the wheels being locked by the 
 tooth A. As the pendulum still goes on, the ball II, and pallet connected 
 with it, are carried by the arm m 7i, and before the pin p again reaches the 
 end of the slit, which had been suddenly withdrawal by the action of A on 
 F, the pendulum comes to rest. It now returns towards the right, loaded 
 with the ball II on the left, and thus the motion lost during the last vibration 
 is restored. When the pin p, by its motion to the right, reaches the end k 
 of i k, the wheel on the right side is unlocked, and at the same instant the 
 weiglit H, being raised from the pendulum by the action of a tooth like B 
 on the pallet D, ceases to act. 
 
 In this ^scapementj both pallets and detents are detached 
 from the pendulum^ except in the moment of unlocking the 
 wlieel^ so that, excepting during this short interval, the pen 
 
518 
 
 TH15 CrPEUA'nVE mechaotc 
 
 dulum may be said to be free during its whole vibration, and 
 of course its motion must be more equable and undisturbed. 
 
 The constructing of a proper "scapement for watches 
 requires peculiar delicacy, owing to the small size of the 
 machine, from which the error of of an inch has as much 
 effect as the error of a whole inch in a common clock. 
 From the necessary lightness of the* balance too, it is ex- 
 tremely difficult to accumulate a sufficient quantity of regu- 
 lating power. This can only be done by giving the balance 
 a great velocity, which is effected by concentrating as much 
 as possible of its weight in the rim, and making its vibrations 
 very wide. The balance-rim of a tolerable watch should 
 pass through at least ten inches in every second. 
 
 Jn considering the most proper ’scapements for w^atches, 
 we may assume the following principle ; viz. : that the oscil- 
 lations of a balance urged by its spring, and undisturbed by 
 extraneous forces, are isochronous. 
 
 In ordinary pocket-watches, the common recoiling ’scape- 
 ment of clocks is still employed, and answers the common 
 purposes of a watch tolerably well, so that, if properly exe- 
 cuted, a good ordinary watch will keep time within a minute 
 in the day. These watches, however, are subject to great 
 variation in their rate of going, from any change in the powet 
 of the wheels. 
 
 The following is considered as the best construction of the common water, 
 ’scapement, and is represented by fig. 525, as it appears when looking straigli. 
 down on the end of the balance arbor. C marks the centre of the balance 
 and verge ; C A represents the upper pallet, or that next the balance, and 
 C B the lower pallet; F and D are two teeth of the crown-wheel, moving 
 from left to right ; E G are two teeth in the lower part, moving from right 
 to left. The tooth D appears as having just escaped from the point of C A, 
 and the tooth Eas having just come in contact with C B. In practice, the 
 ’scapement should not be quite so close, as, by a small inequality of the teeth, 
 D might be kept from escaping at all. In the best proportioned watches, the 
 distance between the front of the teeth, that is, of G F E D, and the axis C of 
 the balance, is ^ of F A, the distance between the points of the teeth. The 
 length C A, C B, of the pallets is | of the same degrees, and the front D H, 
 or F K of the teeth makes an angle of 25" with the axis of the crown-wheel. 
 Tlie sloping side of the tooth must be of an epicycloidal form, suited to the 
 relative motion of the tooth and pallet. 
 
 It appears from these proportions, that by the action of the tooth D, 
 the pallet A can throw out till it reach a, 120® from C L, the line of the 
 crown-wheel axis. To this if we add B C A =95®, we shall have L C a = 120®. 
 Again, B will tlirow out as far on the other side. Now, if from 240®, the 
 sum of the extent of vibration of both pallets, we take 95®, the angle of the 
 pallets, the remainder 145® will express the greatest vibration which the 
 balance can make without striking the front of the teeth. From several 
 causes, however, this measure is too great, and 120® is reckoned a sufficient 
 vibration in the l)est ordinary ’scapement. Encydopci'dki BriUunika. 
 
AND MACHINIST. 
 
 5i9 
 
 In 1812^ Mr. Prior, jim. was rewarded by the Society of 
 Arts for the construction of a remontoirc escape which pos- 
 sesses considerable merit. 
 
 The advantage of this escapement is such as will give an 
 exact and equal impulse to the pendulum without any friction, 
 and which cannot be at all affected by any irregularities or 
 variations arising by the clogging of oil and increasing of 
 friction from the train, except during the very small part of 
 the vibration that the pendulum is removing the spring detents 
 from off the points of the teeth of the escape-wheel, the effect 
 of which can never be discovered in the rate by any variation 
 the oil on the pivots and the increase of friction can ever 
 produce, as long as the wheels will be able to wind up the 
 renovating spring, which will be nearly as long as they can 
 move at all, as the renovating spring has not either to be 
 wound up quick, or to be pushed beyond any catch or spring to 
 keep it in its proper situation, nor can there ever be any increase 
 of friction in winding up the renovating spring, as it is formed 
 in nearly as right a line as possible ; consequently must go 
 almost endlessly without cleaning, and will never require any 
 oil. 
 
 The swing-wheel A, figs. 526 and 527*, has thirty teeth cut in its peri- 
 phery, and is constantly urged forward by the maintaining power, which is 
 supplied by a small weight X, figs. 527 and 527* ; C D are two spring- 
 detents catching the teeth of the wheel alternately, these are, at the proper 
 intervals, unlocked by the parts marked 2 and 3, fig. 526, upon the pen- 
 dulum rod H, intercepting small pins aft, fig. 527, projecting from the 
 detents, as it vibrates towards the one or the other; E is the renovating or 
 remontoire spring, fixed to the same stud F, as the detents ; it is wound up 
 by the highest tooth of the wheel, as seen in fig. 526, (its position when un- 
 wound being shown by the dotted line.) This being a case, suppose a tooth 
 of the wheel is caught by the detent D, which prevents the wheel from 
 moving any further, and keeps the renovating spring from escaping off the 
 point of the tooth ; in this position, the pendulum is quite detached from 
 the wheel ; now, if the pendulum be caused to vibrate towards G, the part 
 of it marked 2 comes against the pin h, fig. 527, projecting from the renovat- 
 ing spring E, and pushes this spring from the point of the wheel’s tooth ; 
 on vibrating a little further, it removes the detent D, which detained the 
 wheel, by the part 3 striking the pin a, fig. 2, which projects from the detent ; 
 the maintaining power of the clock causes the wheel, thus unlocked, to ad- 
 vance, until detained by a tooth resting upon the end of the detent C, on 
 the opposite side ; by this means the renovating spring w ill be clear of the 
 tooth of the wheel as it returns with the pendulum, and gives it an impulse, 
 by its pin b pressing against the part 2 of the pendulum, until the spring 
 comes to the position shown by the dotted line, in w'hich position it is un- 
 wound, and rests against a pin fixed in the cross bar of the plate ; the pen- 
 dulum continues vibrating towards I, nearly to the extent of its vibration, 
 when the part 1 meets the pin in the detent C, and removes it from the 
 wheel, and unlocks it ; the maintaining pow'er now carries it forward, 
 pushing the renovating spring E before it, until another tooth is caught by 
 
520 
 
 THE OPERATIVE. MECHANIC 
 
 Ihe detent D, which detains the wheel in the |)osition first described, the 
 renovating spring being wound up ready to give another impulse to the 
 pendulum. 
 
 The pin h, fig. 527, is not fixed to the renovating spring itself, but is part of 
 a })iece of brass, which is screwed fast to the renovating spring, and is made 
 very slender near the screw which fastens it ; this permits the renovating spring 
 to give way, if, by the weight being taken off’ the clock, or any otlier ac- 
 cident, the escape-wheel should be wound backwards, so as to catch on the 
 detents improperly. 
 
 in this escapement it is necessary to attend to the following 
 observations ; 
 
 1st. That the renovating and detent springs must spring 
 from one centre, and as similarly as possible. 
 
 2dly. That the force applied to the train must be so mucli 
 more than what will wind up the renovating spring, as will 
 overcome the influence of oil and friction on the pivots of the 
 machine. 
 
 3dly. That the renovating spring, when unwound, must rest 
 against the point of the tooth of the wheel, which will be an 
 advantage, as it thereb)" takes as much force olF the tooth of 
 the wheel resting against the detent spring as is equal to the 
 pressure of the renovating spring C, against the face of the 
 tooth of the wheel. 
 
 4thly. The detent springs must be made as slender and 
 light as possible, though whatever force they take from the 
 pendulum by their elasticity in removing them to unlock the 
 wheel, so much force they return to the pendulum in follow- 
 ing it, to where it removed them from, therefore action and 
 reaction will be equal in contrary directions. 
 
 5thly. That it is necessary for the pendulum to remove the 
 detents or renovating springs, much further than it is neces- 
 sary to free the teeth of the wheel, as it will always vibrate 
 on the same arc ; in table clocks it ought to remove them 
 further, so that it can go when not placed exactly level, or 
 what is generally termed out of the beat. 
 
 The following description of a clock escapement, contrived 
 by Mr. Reid, about twelve or fifteen years ago, is extracted 
 from the Edinburgh Encyclopaedia : 
 
 Fig. 528. S W is the swing-wheel, whose diameter may be so large as to 
 be sufficiently free of the arbor of the wheel that runs into its pinion, wliich 
 in eight-day clocks is the third. The teeth of this swing-wheel are cut thus 
 deep, in order that the wheel may be as light as possible, and the strength of 
 the teeth little more than what is necessary to resist the action or force of a 
 common clock weight through the wheels. They are what niay be called 
 the locking-teeth, as will be more readily seen from the use of them after- 
 wards to be explained. Those called the impulse-teeth, consist of very 
 small tempered steel pins, inserted on the surface of the rim of the wheel on 
 one side only. ITiey arc nearly two-tenths of an inch in height; and the 
 
:E S r T 
 
 _From 52 S to 536. 
 
 o^O 
 
 JTetle i- StofJtUu.tejs^J-tr^nd, 
 
AND MACHINIST. 
 
 62 i 
 
 smaller they are so much more room will be given for the tliickness of the 
 pallets. If they have strength to support about 80 or 100 grains, they 
 will be strong enough. There is no rule required for placing them relatively 
 to the locking-teeth, only they may as well be opposite to these teeth 
 as any where else. P P are the pallets whose centre of motion is the same 
 as tiiat at the verge at a. These pallets are formed so as to have the arms 
 sufficiently strong, and at the same time as light as may be. That part 
 where the arms meet at the angle at a, has a steel socket made out of the 
 same piece as the arms, being forged together in this manner. The socket 
 is made to fit well on the verge, on which it is only twisted fast, and is 
 turned pretty small on the outside, in order to allow the arbors of the detents to 
 be laid as close to the verge as may be, so that their centres of motion may 
 coincide as nearly as possible. A perfect coincidence of the centres might 
 be obtained by using a hollow cylinder for the verge, with the detent-arbors 
 running inside of it, but this would have occasioned more trouble. Tliat 
 part of the pallet frame, as it may be called, in which is set the stone for 
 receiving the action or impulse of the small pin teeth, is formed into a rect- 
 angular shape, so as to allow room for a dove-tail groove, into which the 
 stone pallets are fixed, as may be seen at P P, fig. 528, and P, fig. 529, 
 which also gives a side view of the verge at a, and where the socket of the 
 pallets is seen as fixed on the verge. At B, fig. 529, is seen the outer end 
 of one of the stone pallets made flush with the steel. That part of the stone 
 pallets upon which the pin teeth act, may be seen in fig. 528, where they 
 are represented in their respective positions relative to the pin teeth. Their 
 shape or form is exactly that which gives the dead beat. In fig, 528 are 
 seen the detents d d, whose centre of motion is at c c. They are fixed on 
 their arbors by a thin steel socket, made as forged with the detents, much 
 in the same w'ay as the pallets were, as may be seen at c, fig. 530, which 
 gives a side view of one of the detents and its arbor. The screws e e,f f, in 
 the arms of the detents, have a place made to receive them, which is more 
 readily seen in fig. 530, than in fig 528. The screws e e serve for the pur- 
 pose of adjusting that part of the ’scapement connected with the pallets 
 pushing the detents out from locking the wheel, by means of locking the 
 teeth. The ends of the screws e e, on the unlocking, are met by the ends of 
 the stone pallets, one of which is represented at b, fig. 529. The screws ff 
 seem to adjust the locking of the wheel-teeth on the detents ; g g are brass 
 rectangular pieces, or studs, which are fixed to the inside of the pillar frame 
 plate, and maybe near an inch high. The ends of the screws f f rest on 
 the side of these studs, and according as they are more or less screwed 
 through at the ends of the detents, so much less or more hold will the de- 
 tent piece have, of the teeth. These holding pieces of the detents are not 
 represented in the drawing, as tliey would have made other parts of it rather 
 obscure. They are made of stone, and are fitted in by means of a dove- 
 tail cut in a piece left for that purpose, on the inside of the detent-arms, as 
 may easily be conceived from the drawing, where it is represented in part at 
 e, fig. 530 ; and is in the line across the arm with the screw c, which is 
 close by the edge of the detent stone piece, which projects a little beyond 
 the end of the screw. Having described the parts of the ’scapement, we 
 shall now' explain their mode of action. On the left-hand side the pin tooth 
 is represented as having just escaped its pallet, as seen in fig. 528 ; but 
 previous to its having got on to the flanch of this pallet, let us conceive that the 
 back of the pallet, or end piece b of it, had come, in consequence of the 
 motion of the pendulum, to that side, and opposing the screw’ <?, which is 
 in the detent arm, pushes or carries it on with it, and consequently unlocks 
 the tooth of the wheel, w'hich then endeavours to get forward, but the pin 
 
522 
 
 THE OPERATIVE MECHANIC 
 
 tooth at tliis instant of unlocking, meeting with the flanch of the pallet at the 
 lower edge inside, and pushing forward on the flanch, by this means im- 
 pels the pendulum, and after having escaped the pallet, the next locking 
 tooth is received by the detent, on the right-hand side, where the wheel is now 
 again locked. In the mean time, while the pendulum is describing that part of 
 its vibration towards the left hand free and detached, as the pallets are now at 
 liberty to move freely and independently of the small pin teeth, on the return 
 of the pendulum to the right-hand side, the detent, by means of the pallet on 
 that side, is pushed out from locking the wheel, and at the instant of unlock- 
 ing, the wheel gets forward, and the pin tooth is at the same instant ready 
 to get on the flanch of its pallet, and gives new impulse to the pendulum, as 
 is obvious by what is represented in the drawing, fig. 528. After the pin 
 tooth has escaped the pallet, the wheel is again locked on the opposite or 
 left-hand side ; the pendulum moves on to the right freely and independently 
 till the next locking on the left takes place, and so on. It may be observed, 
 that the unlocking takes place when the pendulum is near the lowest point, 
 or point of rest, and of course where its force is nearly a maximum. 
 
 Without attaching any thing to the merits of this ^scape- 
 ment, we may remark that the clock was observed from time 
 to time by a very good transit instrument, and, during a 
 period of eighty-three days, it kept within the second, with- 
 out any interim apparent deviation. This degree of time- 
 keeping seemed to be as much a matter of accident as other- 
 wise ; and cannot reasonably be expected from this or any 
 other clock as a fixed or settled rate. 
 
 This ’scapement being a detached or free ’scapement, can at 
 pleasure be converted into a recoiling or dead beat one, without 
 so much as once disturbing or stopping the pendulum a 
 single vibration. To make dead beat of it, put in a peg of 
 wood, or small wire, to each, so as to raise the detents free of 
 the pallets ; and these being left so as to keep them in the 
 position, the pin-teeth will now fall on the circular parts of 
 the pallets, and so on to the flanch, and the 'scapement is 
 then, to all intents and purposes, a dead beat one. To make 
 a recoiling one of it, let there be fixed to each arbor of the 
 detents, a wire to project horizontally from them about 3i or 
 4 inches long ; the outer ends of the wires must be tapped 
 about half an inch in length ; provide two small brass balls, 
 half an ounce weight each, having a hole through them, and 
 tapped so as to screw on the wires ; the balls can be put 
 more or less home, and be adjusted proportionably to the 
 force of the clock on the pendulum. No recoil will be seen on 
 the seconds’ hand ; yet these will alternately oppose and 
 assist the motion of the pendulum, as much as any recoiling 
 pallets can possibly do ; and as their efforts on the pendulum 
 will be exactly the same, it may be considered as a good 
 recoiling ’scapement. This sort of detached ’scapement, by 
 becoming a dead beat, or a recoiling one, at any time when 
 
AND MACHINIST. 
 
 523 
 
 required, makes it convenient for making various experiments 
 with the different ’scapements. 
 
 Another ^scapement, in which a considerable degree of 
 ingenuity is united with comparative simplicity, is that of 
 Mr. De Lafons. The inventor’s description, and some of his 
 observations, as presented to the Society of Arts, are as 
 follows : 
 
 “Although the giving of an equal impulse to the balance has been 
 already most ingeniously done by Mr. Mudge and Mr. Haley, (from whose 
 great merit I would not wish to detract,) yet the extreme difficulty and 
 expense attending the first, and the very compound locking of the second, 
 render them far from completing the desired object. 
 
 “ The perfections and advantages arising from my improvements on the 
 remontoire detached ’scapement for chronometers, which gives a perfectly 
 equal impulse to the balance, and not only entirely removes whatever 
 irregularities arise from the different states of fluidity in the oil, from the 
 train of wheels, or from the mainspring, but does it in a simpler way than 
 any with which I am acquainted. I trust it will not be thought improper 
 in me to answer some objections made at the examinations before the 
 committee, as I am fully persuaded the more mathematically and critically 
 the improvements are investigated, the more perfect they will prove to be. 
 
 “ It was first observed, that my method did not so completely detach 
 the train of w^heels from the balance as another ^scapement then referred 
 to. I beg leave to remark, that the train of wheels in mine is prevented 
 from pressing against the locking by the whole power of the remontoire- 
 spring ; so that the balance has only to remove the small remaining pressure, 
 which does away that objection, and also that of the disadvantage of 
 detents, as this locking may be compared to a light balance turning on 
 fine pivots, without a pendulum-spring ; and has only the advantage of 
 banking safe at two turns of the balance, and of being firmer, and less 
 liable to be out of repair, than any locking where spring-work is used, but 
 likewise of unlocking with much less power. It was then observed, it 
 required more power to make it go than usual. Permit me to say, it 
 requires no more power than any other remontoire-’scapement, as the 
 power is applied in the most mechanical manner possible. And, lastly, it 
 was said, that it set or required the balance to vibrate an unusually large 
 arch before the piece would go. Tliis depends on the accuracy of the 
 execution, the proportionate diameter and weight of the balance, the 
 strength of the remontoire-spring, and the length of the pallets. If these 
 circumstances are well attended to, it will set but little more than the most 
 generally detached ’scapements.’^ 
 
 A shows the scape-wheel, fig. 534. 
 
 B, the lever-pallet, or an arbor with fine pivots, having at the lower 
 end, 
 
 C, the remontoire or spiral spring fixed with a collar and stud, as 
 pendulum-springs are. 
 
 D, the pallet of the verge, having a roller turning in small pivots for the 
 lever-pallet to act against. 
 
 E, pallets to discharge the locking, with a roller between, as in fig. 535. 
 
 F, the arm of the locking-pallet continued at the other end to make it 
 poise, having studs and screws to adjust and bank tlie quantity of motion. 
 
 a and b, the locking-pallets, being portions of circles, fastened on an 
 arbor turning on fine pivots. 
 
524 
 
 THE OPERATIVE MECHANIC 
 
 G, the triple fork, at the end of the arm of the locking-pallets. 
 
 The centre of the lever-pallet in the draft, is in a right line between 
 the centre of the scape-wheel and the centre of the verge, though in the 
 .model it is not : but may be so or not, as best suits the calliper, &c. 
 
 “ The scape-wlieel A, with the tooth 1, is acting on the lever-pallet B, 
 and has wound up the spring C ; the verge pallet D (turning the way 
 represented by the arrow) tlie moment it comes within the reach of the 
 lever-pallet, the discharging pallet E, taking hold of one prong of the fork, 
 iemoves the arm b", and relieves the tooth 3 from the convex part of the 
 lock a. The wheel goes forward a little, just sufficient to permit the lever- 
 pallet to pass, while the other end gives the impulse to the balance : the 
 tooth 4 of the wheel is then locked on the concave side of the lock d, 
 and the lever-pallet is stopped against the tooth 5, as in fig. 536. So 
 far the operation of giving the impulse, in order again to wind the 
 remontoire-spring, (the other pallet at E, in the return, removing the arm F 
 the contrary direction,) relieves the tooth 3 from the lock I/. The wheel 
 again goes forward, almost the whole space, from tooth to tooth, winds the 
 spiral spring again, and comes into the situation of fig 534, and thus the 
 whole performance is comjjleted. The end of the lower pallet B resting on 
 the point of the tooth 1, prevents the wheel exerting its full force on the 
 lock «, as in fig. 534. The same effect is produced by the pallet lying on 
 the tooth 5, by preventing the wheel from pressing on 5 ; and thus the 
 locking becomes the tightest possible. This ’scapement may be much 
 simplified by putting a spring with a pallet made in it, as in fig. 534, 
 instead of the lever-pallet and spiral spring. The operation will be in 
 other respects exactly the same, avoiding the friction of the pivots of the 
 lever-pallet. This method I prefer for a piece to be in a stale of rest, as a 
 clock, but the disadvantage, from the weight of the spring in different 
 positions, is obvious. The locking may be on tiny two teeth of the wheel, 
 as may be found most convenient.” 
 
 PENDULUMS. 
 
 The pendulum is ii simple ponderous body, so suspended, 
 that it may swing backvrards and forwards, about some fixed 
 point, by the mere force of gravity. 
 
 These alternate ascents and descents of the pendulum are 
 called its oscillations^ or vibrations ; each oscillation being 
 the arc which the pendulum describes from the highest point 
 on one side to the highest point on the other side. The point 
 round wliich the pendulum moves, or vibrates, is called the 
 axis of suspoision, or centre of motion ; and a right line drawn 
 through the centre of motion, parallel to the horizon, and per- 
 pendicular to the plane in which the pendulum moves, is called 
 the axis of oscillation. There is also a certain point within 
 every pendulum, into which, if all the matter that composes 
 the pendulum were collected, or condensed, as into a point, 
 tlie times in which the vibrations would be performed would 
 not be altered by such condensation ; and this point is called 
 the centre of oscillation. The length of the pendulum is 
 always estimated by the distance of this point below the 
 centre of motion, being usually near the bottom of the pen- 
 
AND MACHINIST. 
 
 
 duluni; but in a slender cylinder, or any other uniform prism 
 or 1*0(1 suspended at the top, it is at the distance of one-third 
 from the bottom, or two-thirds below the centre of motion. 
 
 The length of a pendulum, so measured to its centre of 
 osciiiation that it will perform each vibration in a second of 
 time, thence called the seconds’ pendulum, has, in the latitude 
 of London, been generally taken at 39vV or 39^ inches ; 
 but by some very ingenious and accurate experiments, the 
 late celebrated Mr. George Graham found the true length to 
 be 39Vo-oV inches, or 39^ inches very nearly. 
 
 Tlie length of the pendulum vibrating seconds at Paris 
 was found by^Varin, Des Hays, De Glos, and Godin, to be 
 440^ lines ; by Picard, 440J lines; and by Mairan, 440^^ lines. 
 
 As all woods and metals are more or less affected by changes 
 of temperature, many ingenious contrivances have been re- 
 sorted to, to counteract the effects of heat and cold, in length- 
 ening or shortening a pendulum-rod. 
 
 The first person who observed that, by change of tempera- 
 ture, metals changed their length, was Godfroi VVendelinus ; 
 and he who first endeavoured to take advantage of this know- 
 ledge, to counteract the effects of heat and cold upon a pen- 
 dulum, was Graham, who, in the year 1713, suggested that 
 a combination of rods or wires of different metals would have 
 a tendency to that effect ; but being of opinion that this would 
 not be quite adequate to the desired purpose, he did never, 
 we believe, put it in execution. Still continuing his observa- 
 tions, he, a short time afterwards, conceived that mercury, 
 from its great expansion by heat, was more adapted to the 
 end he was pursuing, and accordingly we find, that, by the 
 9th of June, 1722, he had constructed a clock which had a 
 pendulum upon this principle, and which he kept continually 
 going, without having either the pendulum or the hands 
 altered, for the space of three years and four months, during 
 which he found the errors of his were but about one-eighth 
 part of those of one of the best sort of common clocks, with 
 which he had compared it. This pendulum, which is called 
 the mercurial pemdiilum^ consists of a rod of brass, branched 
 towards the lower end, so as to embrace a cylindric glass jar 
 13 or 14 inches long, and about two inches diameter ; which, 
 being filled about 12 inches deep with mercury, forms the 
 weight or ball of the pendulum. In adjusting this pendulum, 
 if the expansion of the rod be too great for that of the mer- 
 cury, more mercury must be poured into the vessel ; but if 
 the expansion of the mercury exceed that of the rod, so as 
 to occasion the clock to go fast with heat, some of the mercury 
 
52G 
 
 THE OPERATIVE MECHANIC 
 
 must be taken out^ to shorten the column. This pendulum, 
 though troublesome to construct, because any filling in or 
 taking out of the mercury from the cylinder or glass jar, to 
 bring about the compensation, will cause a change of place 
 in the index-point on the graduated arch or index-plate, if 
 such a thing be used, is, notwithstanding some defect may 
 arise from the expansion of the mercury commencing sooner 
 than that of the rod, of much practical excellence. The mer- 
 curial pendulum has been much improved by Reid ; for an 
 account of which we must refer our readers to the article 
 ‘‘ Horology,” written by this gentleman, and inserted in the 
 Edinhurgh EncyclopcBdia, 
 
 Mr. Harrison, of whom we have already spoken under the 
 article Chronometers, some time previous to 1726, constructed 
 a pendulum in which the compensation was effected by the 
 opposite contraction of different metals. This pendulum, 
 called the gridiron-pendidum, from, we suppose, its bearing 
 a near resemblance to the culinary implement of that name, 
 was made of five steel and four brass rods, placed in alternate 
 order, the middle rod, by which the pendulum-ball is sus- 
 pended, being of steel. These rods are so connected with 
 each other at their ends, that while the expansion of the steel 
 rods has a tendency to lengthen the pendulum, the expansion 
 of the brass rods, acting upwards, tends to shorten it, so that 
 by the combined effect the pendulum is invariably preserved 
 of the same length. This is a very ingenious and simple 
 contrivance, and the only objections we have heard urged 
 against this mode of compensation are, 1st. the difficulty of 
 exactly adjusting the length of the rods ; 2dly. of propor- 
 tioning their thickness, so that they shall all begin to con- 
 tract or expand at the same instant ; 3dly. the connecting 
 bars of a pendulum thus constructed are apt to move by starts; 
 4thly. this kind of pendulum is more exposed to the air's 
 resistance than a simple pendulum. 
 
 Other modes of constructing pendulums on the principle of 
 the opposite contraction of metals have been contrived by 
 other ingenious artists, among whom we may notice Ellicott, 
 Cumming, Troughton, Reid, and Ward. 
 
 In Ellicott’s pendulum the ball was adjustable by levers, 
 thence called the lever -pendulum^ which can never be equal 
 to those in which the expansion and contraction act by con- 
 tact in the direct line of the pendulum-rod ; the construction 
 nevertheless evinced great ingenuity. The rod of this pen- 
 dulum was composed of two bars, one of brass, and the other 
 of steel. It had two levers,. each sustaining its half of the 
 
AND MACHINIST. 
 
 527 
 
 ball or weight, with a spring under the lower part of the ball 
 to relieve the levers from a considerable part of its weight, 
 and so to render their motion more smooth and easy. These 
 levers were placed within the ball, and each had an adjusting 
 screw to lengthen or shorten the lever, so as to render the 
 adjustment the more perfect. See the Philos. Transact. 
 voL xlvii. p. 479 ; where Mr. Ellicott’s methods of construc- 
 tion are described and illustrated by figures. 
 
 This pendulum was much improved by Gumming, who 
 conceived that where there were two bars only, a flexure and 
 unequal bearing w'ould take place, and consequently an exact 
 compensation could not be eftected. To remedy this, he 
 constructed a pendulum of one flat bar of brass, and two bars 
 of steel, and used three levers within the ball of the pendulum, 
 wEereas Mr. Ellicott used only two. Among many other 
 ingenious contrivances for the more accurate adjusting of this 
 pendulum to mean time, it is provided with a small ball and 
 screw below’ the principal ball or weight, one entire revolu- 
 tion of w’hich on its screw will only alter the rate of the 
 clock’s going one second per day ; and its circumference is 
 divided into 30, one of which divisions will therefore alter its 
 rate of going one second in a month. 
 
 Troughton’s tubular-pendulum, which acts on the prin- 
 ciple of the gridiron-pendulum, is a very neat and ingenious 
 contrivance. It is constructed of an exterior tube of brass, 
 reaching from the bob nearly to the top, within which is 
 another tube, and five brass wires in its belly, so disposed as 
 to produce altogether, (like Harrison’s gridiron-pendulum,) 
 three expansions of steel dowTiw'ards, and two of brass up- 
 w’ards, whose lengths being inversely proportioned to their 
 dilatation, when properly combined, destroy the whole effect 
 that either metal w^ould have singly. The small visible part 
 of the rod, near the top, is a brass tube, wEose use is to cover 
 the upper end of the middle wire, which is single, and other- 
 wise unsupported. Drawings of this pendulum may be seen 
 in Nicholson s Journal, No. 36, N.S. 
 
 Reid’s pendulum is composed of a zinc tube, and three long 
 and one short steel rods, connected by means of traverses. 
 Two of these long rods are inserted at one end in the ball of 
 the pendulum, and terminate at the other in the upper tra- 
 verse, which keeps them exactly parallel with respect to each 
 other. At the lower ends of these rods, not far above the 
 ball, is another traverse, in the middle of w’hich the short 
 steel rod is pinned, descending thence through the centre of 
 the ball. Another traverse is placed a little above this, on 
 
52S 
 
 HIK OPERATIVK MKCHANIC, &C. 
 
 the centre of which the zinc tube rests, extending upwards, 
 and pressing against, or rather pressed by the upper traverse. 
 The third or centre steel rod passes through a hole in the 
 upper traverse, equidistant from each of the other two steel 
 rods, thence down the zinc tube, and finally is pinned to the 
 second traverse, or that traverse on which the zinc tube rests. 
 By this means, the centre steel rod, when lengthened by heat, 
 will make the lower end of the zinc tube descend wdth it ; 
 but the same cause which lengthens the steel rod downwards 
 will expand the zinc tube upwards, and this will carry up the 
 two outside steel rods with which the ball of the pendulum is 
 connected ; their expansion downwards, as well as that of 
 the centre rod, is compensated by the upward expansion of 
 the zinc tube. In constructing a pendulum upon this prin- 
 ciple, it would be proper to have a few holes in the tube, for 
 the purpose of admitting air more freely to the centre rod. 
 
 Ward’s pendulum consists of two flat bars of steel, and one 
 of zinc, connected together by three screws. The description 
 which has been given of it in the Transactions of the Society 
 of Arts, &c. for the year 1807, the pamphlet which 
 Mr. Ward published at Blandford in 1808, contain sufficient 
 details to enable any common clock-maker to copy it. 
 
 Before we conclude this article, we shall briefly notice the 
 sympathy or mutual action of the pendulums of clocks. 
 
 It is now nearly a century since it was known that when 
 two clocks are set agoing on the same shelf, they will disturb 
 each other ; that the pendulum of the one will stop that of 
 the other ; and that the pendulum which was stopped will, 
 after a while, resume its vibrations, and, in its turn, stop that 
 of the other clock, as was observed by the late Mr. John 
 Ellicott. When two clocks are placed near one another, in 
 cases very slightly fixed, or when they stand on the thin 
 boards of a floor, it has been long known that they will affect 
 a little the motions of each other’s pendulum. Mr. Ellicott 
 observed, that two clocks resting against the same rail, which 
 agreed to a second for several days, varied T 86'^ in twenty- 
 four hours when separated. The slower having a longer 
 pendulum, set the other in motion in 16 V minutes, and 
 stopped itself in 36-i- minutes. 
 
AND MACHINIST. 
 
 5S9 
 
 BUILDING. 
 
 Under this general term, which implies the construction 
 of an edifice according to the rules laid down by the differ- 
 ent artificers employed, we purpose to treat of the respect- 
 ive business of the Mason, Bricklayer, Carpenter, Joiner, 
 Plasterer, Plumber, Painter, and Glazier; previous to which 
 it will be necessary to consider the sinking of the foundation, 
 the due mixture of the ingredients which compose the 
 mortar, and the art of making bricks ; upon the whole of 
 which materially depends the stability of an edifice. 
 
 As firmness of foundation is indispensable, wherever 
 it is intended to erect a building, the earth must be pierced 
 by an iron bar, or struck with a rammer, and if found to 
 shake, must be bored with a well-sinker’s implement, in 
 order to ascertain whether the shake be local or general. 
 If the soil is in general good, the loose and soft parts, if 
 not very deep, must be excavated until the labourers arrive 
 at a solid bed capable of sustaining the pier or piers to be 
 built. If not very loose, it maybe made good by ramming 
 into it very large stones, packed close together, and of a 
 breadth proportionate to the intended weight of the build- 
 ing ; but where very bad, it must be piled and planked. 
 
 In places where the soil is loose to any great depth, and 
 over which it is intended to place apertures, such as doors, 
 windows, &c. while the parts on which the piers are to 
 stand are firm, .the best plan is to turn an inverted arch un- 
 der each intended aperture, as then the piers in sinking will 
 carry with them the inverted arch, and by compressing the 
 ground compel it to act against the under sides of the arch, 
 which, if closely jointed, so far from yielding, will, with 
 the abutting piers, operate as one solid body ; but, on the 
 contrary, if this expedient of the inverted arch is not 
 adopted, the part of the wall under the aperture, being of 
 less height, and consequently of less weight than the piers, 
 will give way to the resistance of the soil acting on its base> 
 and not only injure the brick- work between the apertures^ 
 but fracture the windcAV-heads andcills. 
 
 2m 
 
530 
 
 THE OPERATIVE MECHANIC 
 
 In constructing so essential a part as the arch, great at- 
 tention must be paid to its curvature, and we strongly re- 
 commend the parabolic curve to be adopted, as the most 
 effectual for the purpose ; but if, in consequence of its 
 depth, this cannot conveniently be introduced, the arch 
 should never be made less than a semi-circle. The bed of 
 the piers should be as uniform as possible, for, though the 
 bottom of the trench be very firm, it will in some degree 
 yield to the great weight that is upon it, and if the soil be 
 softer in one part than in another, that part which is the 
 softest, of course will yield more to the pressure, and cause 
 a fracture. 
 
 If the solid parts of the trench happen to be under the in- 
 tended apertures, and the softer parts where piers are want- 
 ed, the reverse of the above practice must be resorted to ; 
 that is, the piers must be built on the firm parts, and have 
 an arch that is not inverted between them. In performing 
 this, attention must be paid to ascertain whether the pier 
 will cover the arch ; for if the middle of the pier rest over 
 the middle of the summit of the arch, the narrower the 
 pier is, the greater should be the curvature of the arch at 
 its apex. When suspended arches are used, the intrados 
 ©light to be kept clear of the ground, that the arch may 
 have its due effect. 
 
 When the ground is in such a state as to require the foun- 
 dation merely to be rammed, the stones are hammer- dress- 
 ed, so as to be as little taper as possible, then laid of a 
 breadth proportioned to the iveight that is to be rested upon 
 them, and afterwards well rammed together. In general, 
 the lower bed of stones may be allowed to project about a 
 foot from the face of the wall on each side, and on this bed 
 another course may be laid to bring the bed of stones on a 
 level with the top of the trench. The breadth of this 
 upper bed of stones should be four inches less than the lower 
 one ; that is, projecting about eight inches on either side 
 of the wall. In all kinds of walling, each joint of every 
 course must fall as nearly as possible in the centre, be- 
 tween two joints of the course immediately below it ; for 
 in all the various methods of laying stones or bricks, the 
 principal aim is to procure the greatest lap on each other. 
 
 MORTAR. 
 
 In making mortar, particular attention must be paid 
 to the quality of the sand, and if it contain any propor- 
 
AND MACHINIST. 
 
 531 
 
 lion of clay or mud^ or is brought from the sea-shore and 
 contains saline particles, it must be washed in a stream 
 Df clear water till it be divested of its impurities. The 
 necessity of the first has been clearly proved by Mr. Smeaton, 
 ivho, in the course of a long and meritorious attention to 
 lis profession of an engineer, has found, that when mortar, 
 :hough otherwise of the best quality, is mixed with a small 
 3roportion of unburnt clay, it never acquires that hardness 
 vhich, without it, it would have attained 5 and, with respect 
 o the second, it is evident, that so long as the sand contains 
 ialine particles it cannot become hard and dry. The sharper 
 ind coarser the sand is the better for the mortar, and the less 
 be quantity of lime to be used; and sand being the 
 cheapest of the ingredients which compose the mortar, 
 tis more profitable to the maker. The exact proportions 
 )f lime and sand are still undetermined ; but in general no 
 nore lime is required than is just sufficient to surround 
 he particles of the sand, or sufficient to preserve the 
 lecessary degree of plasticity. 
 
 Mortar, in which sand forms the greater portion requires 
 ess water in its preparation, and consequently is sooner 
 let. Jt is also harder and less liable to shrink in drying, 
 lecause the lime, while drying, has a greater tendency to 
 brink than sand, which retains its original magnitude. 
 The general proportions given by the London builders is H 
 jwt., or 37 bushels, of lime to loads of sand ; but if 
 iroper measures be taken to procure the best burnt lime 
 ind the best sand, and in tempering the materials, a greater 
 portion of sand may be used. There is scarcely any 
 uortar that has the lime well calcined, and the com- 
 position well beaten, but that will be found to require 
 :wo parts of sand to one part of unslacked lime ; and it is 
 ivorthy of observation, that the more the mortar is beaten 
 be less proportion of lime suffices. 
 
 Many experiments have been made with a view to obtain 
 the most useful proportion of the ingredients, and among 
 the rest Dr. Higgins has given the following : — 
 
 Lime newly slacked one part. 
 
 Fine sand three parts ; and 
 Coarse sand four parts. 
 
 He also found that one-fourth of the lime of bone-ashes 
 greatly improved the mortar, by giving it tenacity, and ren- 
 dering it less liable to crack in the drying. 
 
 It is best to slack the lime in small quantities as required 
 2 M 2 
 
THE OPERATIVE MECHANIC 
 
 for 11 se^ about a bushel at a time, in order to secure to the 
 mortar such of its qualities as would evaporate were it 
 aUlowed to remain slacked for a length of time. But if the 
 mortar be slacked for any considerable time previous to 
 being used, it should be kept covered up, and when wanted 
 be re-beaten. If care be taken to secure it from the action 
 of the atmosphere, it may thus remain covered up for a 
 considerable period without its strength being in the least 
 affected ; and, indeed, some advantages are gained, for 
 it sets sooner, is less liable to crack in the drying, and is 
 harder when dry. 
 
 Grout, which is a cement containing a larger proportion 
 of water than the common mortar, is use'd to run into the 
 narrow interstices and irregular courses of rubble-stone 
 walls ; and as it is required to concrete in the course of a 
 day, it is composed of mortar that has been a long time 
 made and thoroughly beaten. 
 
 Mortar, composed of pure lime, sand, and water, 
 may be employed in the linings of reservoirs and aque- 
 ducts, provided a sufficient time is allowed for it to dry 
 before the water is let in ; but if a sufficient time is not 
 allowed, and the water is admitted while the mortar is wet, 
 it will soon fall to pieces. There are, however, certain in- 
 gredients which may be put into the common mortar to 
 make it set immediately under the water; or, if the quick- 
 lime composing the mortar contain in itself a certain por- 
 tion of burnt clay, it will possess this property. For further 
 information on this head the reader is referred to the 
 s u i) -h ead — Plastering, 
 
 BRICKS. 
 
 The earth best adapted for the manufacture of brick is of 
 a clayey loam, neither containing too much argillaceous mat 
 ter, which causes it to shrink in the drying, nor too much 
 sand, which has a tendency to render the ware both heai^ 
 and brittle. It should be dug two or three years before it 
 is wrought, that it may, by an exposure to the action of the 
 atmosphere, lose the extraneous matter of which it is pos- 
 sessed when first drawn from its bed ; or, at least, should 
 be allowed to remain one winter, that the frost may mellow 
 and pulverize it sufficiently to facilitate the operation of 
 tempering. As the quality of the brick is greatly dependent 
 upon the tempering of the clay, great care should be taken 
 to have this part of the process well done. Formerly the 
 manner of performing it consisted in throwing the clay into 
 
AND MACHINIST. 
 
 633 
 
 shallow pits, and subjecting it to 'the tread of men and 
 oxen ; but this method has of late been superseded by the 
 clay or pug mill, which is a very eligible, though simple 
 machine. 
 
 The clay or pug mill consists of a large vertical cone, 
 having strong knives with a spiral arrangement and inclina- 
 tion fixed on its internal surface. Passing through the 
 centre, and terminating in a pivot at the bottom, is a strong 
 perpendicular shaft with similar radiating knives, so that 
 the knives by the revolution of the shaft, cut, separate, and 
 purify the clay, till it be reduced to a homogeneous paste, 
 which passes through an orifice at the bottom into a receiver 
 placed for that purpose. The clay is taken from the re- 
 ceiver to the moulder’s bench, and is, either by a lad or a 
 woman, cut into pieces somewhat larger than the mould, 
 and passed on to the moulder, who works it into a mould, 
 previously dipped in sand, and strikes off the superfluous 
 parts with a flat smooth piece of wood. In this country the 
 mould used is about ten inches in length, and five inches in 
 breadth, and the bricks when burnt are about nine inches 
 long, four and a half inches broad, and two and a half inches 
 thick. The degree of sh ringing, however, is various, ac- 
 cording to the temper and purity of the clay, and the de- 
 gree of heat attained in the burning. A handy moulder is 
 calculated to mould from about 5000 to 7000 per day. From 
 the moulder’s bench the bricks are carried to the hack, and 
 arranged somewhat diagonally, one above the other, and two 
 edgewise across, with a passage between the heads of each 
 for the admission of air, till they be eight bricks in height. 
 They are then left to dry. The time they take ere they re- 
 require shifting depends entirely upon the weather, which 
 when fine will be but a few days ; they are then turned and 
 re-set wider apart, and in six or eight days are ready for the 
 clamp or kiln. 
 
 Clamps are generally used in the vicinity of London. 
 They are made of the bricks to be burnt, and are commonly 
 of an oblong form. The foundation is made either with the 
 driest of the bricks just made, or with the coanmonest kind 
 of brick, called place bricks. The bricks to be burnt are 
 arranged tier upon tier as high as the clamp is intended to 
 be, and a stratum of breeze or cinders to the depth of two 
 or three inches is strewed between each layer of bricks, and 
 the whole is finally covered with a thick stratum of breeze. 
 At the west end of the clamp a perpendicular fire-place of 
 about three feet in height is constructed, and flues are formed 
 
534 
 
 iHfi OPERATIVE MECHANIC 
 
 by arching the bricks over so as to leave a space of about 
 a brick in width. The flues run straight through the clamp, 
 and are filled with a mixture of coals, w’ood, and breeze, 
 which are pressed closely together. If the bricks are re- 
 quired to be burnt off quickly, which can be accomplished 
 in the space of from twenty to thirty days according to the 
 state of the weather, the flues must not exceed six feet dis- 
 tance apart ; but if there is no urgent demand, the flues 
 need not be nearer than nine feet, and the clamp may be 
 allowed to burn slowly. 
 
 Coke has been recommended as a more suitable fuel for 
 bricks than either coal or wood, as the dimensions of the 
 flues and the stratum of the fuel are not required to be so 
 great, which, since the measurement of the clamp has been 
 restricted to certain limits by the interference of the legis- 
 lature, is a point of some consideration ; besides, the heat 
 arising from the coke is more uniform and more intense than 
 what is produced by the other materials, so that the burn- 
 ing of the bricks is more likely to be perfect through- 
 out. The saving which is thus produced may be calculated 
 at about 32 per cent. 
 
 Kilns are also in common use, and are in many respects 
 preferable to the clamp, as less waste arises, less fuel is 
 consumed, and the bricks are sooner burnt. A kiln will 
 burn about 20,000 bricks at a time. The walls of a kiln are 
 about a brick and a half thick, and incline inwards towards 
 the top, so that the area of the upper part is not more than 
 114 square feet. The bricks are set on flat arches, with 
 holes left between them, resembling lattice-work ; and, 
 when the kiln is completed, are they covered with pieces of 
 broken bricks and tiles, and some wood is kindled and put 
 in to dry them gradually. When sufficiently dried, which 
 is known by the smoke changing from a dark to a light 
 transparent colour, the mouths of the kiln are stopped 
 with pieces of brick, called shmlog, piled one upon ano- 
 ther, and closed over with wet brick-earth. The shinlogs 
 are carried so high as just to leave room for one faggot to 
 be thrust into the kiln at a time, and when the brush-wood, 
 furze, heath, faggots, &c. are put in, the fire is kindled, 
 and the burning of the kiln commences. The fire is kept 
 up till the arches assume a white appearance, and the 
 flames appear through the top of the kiln ; upon which the 
 fire is allowed to slacken, and the kiln to cool by degrees. 
 This process of alternately heating and slacking the kiln is 
 continued till the bricks are thoroughly burnt, which, in 
 
AND MACHINIST. 
 
 535 
 
 general, is in the space of forty-eight hours. The practice 
 of steeping bricks in water after they have been burned, 
 and then. burning them again, has the effect of considerably 
 improving the quality. 
 
 Bricks are of several kinds, the most usual of which are 
 marls, stocks, and place bricks ; but there is little dif- 
 ference in the mode of manufacturing them, except that 
 great care is taken in preparing and tempering the marls. 
 
 The finest marls, called firsts, are selected /or the arches 
 of doorways, &c. and are rubbed to their proper form and 
 dimensions : and the next best, called seconds, for the 
 principal fronts. The colour, a light yellow, added to the 
 smooth texture, and superior durability of the marls, give 
 them the precedence of the other descriptions of brick. 
 
 Grey stocks are somewhat like the seconds, but of infe- 
 rior quality. 
 
 Place bricks, sometimes called pickings, sandal, or samel 
 bricks, are such as from being the outermost in the clamp 
 or kiln, have not been thoroughly burned, and are, in con- 
 sequence, soft, of uneven texture, and of a red colour. 
 
 There are also burrs or clinkers, arising from the bricks 
 being too violently burned, and sometimes several bricks are 
 found run together in the kiln. They derive their colour from 
 the nature of the soil of which they are composed, which, 
 in general, is very pure. The best kind are used as cutting 
 bricks, and are called red rubbers. In old buildings they 
 are very frequently to be seen ground to a fine smooth sur- 
 face, and set in putty instead of mortar, as ornaments over 
 arches, windows, door-ways, &c. ; but though there are 
 many beautiful specimens of red brick-work, yet these 
 bricks cannot be judiciously used for the front walls of build- 
 ings. This objection arises from the colour being too heavy, 
 and fi'om its conveying to the mind, in the summer months, 
 an unpleasant idea of heat ; to which may be added, that as 
 the fronts of the buildings have a greater or less proportion 
 af stone and painted wood-work, the contrast in the colours 
 is altogether injudicious. The colour of grey stocks, 
 on the contrary, assimilates so much with the stones and 
 paint, that they have obtained, in and near London, univer- 
 sal preference. 
 
 At the village of Hedgerley, near Windsor, red bricks 
 are made which will stand the greatest heat : they are called 
 Windsor bricks. 
 
 Bricks used for paving, are generally about an inch and a 
 half in breadth ; and, beside these, there are paving tiles. 
 
THE OPERATIVE MECHANIC 
 
 636 
 
 which are made of a stronger clay, and are of a red colour. 
 The largest are about twelve inches square, and one inch 
 and a half thick : the next, though called ten-inch tiles, are 
 about nine inches square, and one inch and a quarter thick. 
 
 About the year 1795, a patent was obtained by Mr. Cart- 
 wright, for an improved system of making bricks, of 
 which the following extract will furnish the reader with 
 all necessary information. 
 
 “ Imagine a common brick, with a groove or rabate on each side down 
 the middle, rather more than half the width of the side of the brick ; a 
 shoulder will thus be left on either side of the groove, each of which will 
 be nearly equal to one quarter of the width of the side of the brick, or to 
 one half of the groove or rebate. A course of these bricks being laid 
 shoulder to shoulder, they will form an indented line of nearly equal 
 divisions, the grooves or rebates being somewhat wider than the ad- 
 joining shoulders, to allow for the mortar or cement. When the course 
 js laid on, the shoulders of the bricks, which compose it, will fall into 
 grooves of the first course, and the shoulders of the first course, will fit 
 into the grooves or rabates of the second, and so with every succeeding 
 course. Buildings constructed with this kind of brick, will require no 
 bond timbers, as an universal bond runs through the whole building, and 
 bolds all the parts together ; the walls of which will neither crack nor 
 bilge without breaking through themselves. When bricks of this con- 
 struction are used for arches, the sides of the grooves should form the 
 radii of the circle, of which the intended arch is a segment ; yet if the 
 circle be very large, the difference of the width at the top and bottom will 
 be so very trifling, as to render a minute attention to this scarcely if at all 
 necessary. In arch-work, the bricks may either belaid in mortar, or dry, 
 and the interstices afterwards filled up by pouring in lime, putty, plaster of 
 Paris, &c. Arches upon this principle, having any lateral pressure, can 
 neither expand at the foot, nor spring at the crown, consequently they 
 want no abutments, requiring only perpendicular walls to be let into, or 
 to rest upon ; neither will they want any superincumbent weight on the 
 crown to prevent their springing up. The centres also may be struck 
 immediately, so that the same centre, which never need be many feet 
 wide, may be regularly shifted as the work proceeds. But the most 
 striking advantage attending this invention is, the security it affords 
 against the ravages of fire ; for, from the peculiar properties of this 
 kind of arch, requiring no abutments, it may be laid upon, or let into 
 common walls, no stronger than what is required for timbers so as to ad- 
 mit of brick floorings.” 
 
 Having said thus much on the laying of the foundation, 
 the mixing of the mortar, and the manufacture of the 
 brick, we shall next proceed to treat on the principles of 
 the art of masonry, as practised in the present day. 
 
 MASONRY, 
 
 :Is the art of cutting stones, and building them into a 
 mass, so as to form the regular surfaces which are required- 
 in the construction of an edifice. ^ 
 
AND MACHINIST. 
 
 537 
 
 The chief business of the mason is to prepare the stones, 
 make the mortar, raise the wall with the necessary breaks, 
 projections, arches, apertures, &c., and to construct the 
 vaults, &c. as indicated by the design. 
 
 A wall built of unhewn stone, whether it be built with 
 mortar or otherwise, is called a rubble ivalL Rubble work 
 is of two kinds, coursed and uncoursed. In coursed rub- 
 ble the stones are gauged and dressed by the hammer, 
 and thrown into different heaps, each heap containing stones 
 of equal thickness ; and the masonry, which may be of dif- 
 ferent thicknesses, is laid in horizontal courses. In un- 
 coursed rubble the stones are placed promiscuously in the 
 wall, without any attention being paid to the placing them 
 in courses ; and the only preparation the stones undergo, 
 is that of knocking off the sharp angles with the thick 
 end of a tool called a scahling hammer. Walls are ge- 
 nerally built with an ashlar facing of fine stone, averaging 
 about four or five inches in thickness, and backed with rub- 
 ble work or brick. 
 
 Walls backed with brick or uncoursed rubble, are liable 
 to become convex on the outside, from the great number 
 of joints, and the difficulty of placing the mortar, 'which 
 shrinks in proportion to the quantity, in equal portions, 
 in each joint ; consequently, walls of this description are 
 much inferior to those where the facing and backing are 
 built of the same material, and with equal care, even though 
 both of the sides be uncoursed. When the outside of a 
 wall is faced with ashlar, and the inside is coursed rubble, 
 the courses of the backing should be as high as possible, 
 and set within beds of mortar. Coursed rubble and brick 
 backings are favourable for the insertion of bond timber ; 
 but, in good masonry, wooden bonds should never be in 
 continued lengths, as in case of either fire or rot the wood 
 will perish, and th6 masonry will, by being reduced, be 
 liable to bend at the place where the bond was inserted. 
 
 When timber is to be inserted into walls for the purposes 
 of fastening buttons for plastering, or skirting, &c., the 
 pieces of timber ought to be so disposed that the ends of 
 the pieces be in a line with the wall. 
 
 In a wall faced with ashlar, the stones are generally about 
 2 feet or 2^ feet in length, 12 inches in height, and 8 inches 
 in thickness. It is a very good plan to incline the back of 
 each stone, to make all the backs thus inclined run in the 
 same direction, which gives a small degree of lap in the 
 setting of the next course ; whereas, if the backs are paral • 
 
THE OPERATIVE MECHANIC 
 
 538 
 
 lei to the front, there can be no lap where the stones run of 
 an equal depth in the thickness of the wall. It is also ad* 
 vantageous to the stability of the wall to select the stones, so 
 that a thicker and a thinner one may succeed each other 
 alternately. In each course of ashlar facing, either with 
 rubble masonry, or brick backing, thorough-stones should 
 occasionally be introduced, and their number be in pro- 
 portion to the length of the course. In every succeeding 
 course, the thorough stones should be placed in the middle 
 of every two thorough-stones in the course below ; and 
 this disposition of bonds should be punctually attended to 
 in all cases where the courses are of any great length. 
 Some masons, in order to prove that they have introduced 
 sufficient bonds into their work, choose thorough-stones of 
 a greater length than the thickness of the wall, and after- 
 wards cut off the ends ; but this is far from an eligible plan, 
 as the wall is not only subject to be shaken, but the stone is 
 itself apt to split. In every pier, between windows and 
 other apertures, every alternate jamb-stone ought to go 
 through the wall with its bed perfectly level. When the 
 jamb-stones are of one entire height, as is frequently the 
 case when architraves are wrought upon them, upon the 
 lintel crowning them, and upon the stones at the ends of 
 the courses of the pier which are adjacent to the architrave- ' 
 jamb, every alternate stone ought to be a thorough-stone: 
 and if the piers between the apertures be very narrow, no 
 other bond-stone is required ; but where the piers are wide, 
 the number of bond-stones are proportioned to the space. 
 Bond-stones must be particularly attended to in all long 
 courses below and above windows. 
 
 All vertical joints, after receding about an inch with a close 
 joint, should widen gradually to the back, thereby forming hol- 
 low spaces of a wedge- like figure, for the reception of mortar, 
 rubble, &c. The adjoining stones should have their beds and 
 vertical joints filled, from the face to about three quarters 
 of an inch inwards, \vith oil and putty, and the rest of the 
 beds must be filled with well-tempered mortar. Putty ce- 
 ment will stand longer than most stones, and will even 
 remain, permanent when the stone itself is mutilated. All 
 walls cemented with oil-putty, at first look unsightly ; but 
 this disagreeable effect ceases in a year or less, when, if 
 care has been taken to make the colour of the putty suitable 
 to that of the stone, the joints will hardly be perceptible. 
 
 In selecting ashlar, the mason should take care that each 
 stone invariably lays on its natural bed; as from ca’eless- 
 
AND MACHINIST. 
 
 539 
 
 Dess in this particular^ the stones frequently flush at the 
 joints, and sooner admit the corrosive power of the atmos- 
 phere to take effect. 
 
 It ought also to be observed, that, in building walls, or 
 insulated pillars of small horizontal dimensions, every 
 stone should have its bed perfectly level, and be without 
 any concavity in the middle ; because, if the beds are con- 
 cave, the joints will most probably flush when the pillars 
 begin to sustain the weight of the building. Care should 
 also be taken, that every course of masonry in such piers 
 be of one stone. 
 
 Having thus given to the practical mason an outline 
 of the subject of walling, we will proceed to the con- 
 sideration of the more difficult branches of the art, that 
 of constructing arches and vaults. 
 
 DEFINITIONS. 
 
 An arch^ in masonry, is that part of a building which is 
 suspended over a given plane, supported only at its extre- 
 mities, and concave towards the plane. 
 
 The upper surface of an arch is called the extrados ; and 
 the under surface, or that which is opposite the plan, the 
 intrados. 
 
 The supports of an arch are called the spring tvalls. 
 
 The springing lines, are those common to the supports 
 and the intrados ; or the line which forms the intersection 
 of the arch with the surface of the wall which supports it. 
 
 The chord, or span, is a line extending from one springing 
 line to the opposite one. 
 
 Section of the hollow of the arch, is a vertical plane, sup- 
 posed to be contained by the span and the intrados. 
 
 The height, or rise of the arch, is a line drawn at right 
 angles from the middle of the chord, or spanning line, to 
 the intrados. 
 
 The crown of the arch is that part which the extremity of 
 the perpendicular touches. 
 
 The haunches, or flanks, of the arch, are those parts of 
 the curve betw’een the crown and the springing line. 
 
 When the base of the section, or spanning line, is paral- 
 lel to the horizon, the section will consist of two equal and 
 similar parts, so that when one is applied to the other, they 
 will be found to coincide. 
 
 Arches are variously named according to the figure of the 
 section of a solid that would fill the void, as tircular, ellip • 
 
THE OPERATIVE MECHANIC 
 
 540 
 
 tical, cycloidal^ catenarian, paraholical, &c. There are also 
 pointed, composite, and lancet, or Gothic arches. 
 
 A rampant arch is when the springing lines are of two 
 unequal heights. 
 
 When the intrados and extrados of an arch are parallel, it 
 is said to be extradossed. 
 
 There are, however, other terms much used by masons ; 
 for example, the semicircular are called perfect arches, and 
 those less than a semicircle, imperfect, surhused, or dimi- 
 nished arches. 
 
 Arches are also called surmounted, when they are higher 
 than a semicircle. 
 
 A vault is an arch used in the interior of a building, 
 overtopping an area of a given boundary, as a passage, or 
 an apartment, and supported by one or more walls, or pil- 
 lars, placed without the boundary of that area. 
 
 Hence an arch in a wall is seldom or never called a vault ; 
 and every vault may be called an arch, but every arch can- 
 not be termed a vault. 
 
 A groin vault, is a complex vault, formed by the intersec- 
 tion of two solids, whose surfaces coincide with the intra- 
 dos of the arches, and are not confined to the same heights. 
 Anarch is said to stand upon splayed jambs, when the 
 springing lines are not at right angles to the face of the wall. 
 
 In the art of constructing arches and vaults, it is neces- 
 sary to build them in a mould, until the whole is closed : 
 the mould used for this purpose is called a centre. The in- 
 trados of a simple vault is generally formed of a portion of 
 a cylinder, cylindroid, sphere, or spheroid, that is, never 
 greater than the half of the solid : and the springing lines 
 which terminate the walls, or when the vault begins to 
 rise, are generally straight lines, parallel to the axis of the 
 cylinder, or cylindroid. 
 
 A circular wall is generally terminated wdth a spherical 
 vault, which is either hemispherical, or a portion of a 
 sphere less than an hemisphere. 
 
 Every vault which has an horizontal straight axis, is call- 
 ed a straight vault ; and in addition to what we have already 
 said, the concavities which two solids form at an angle, re- 
 ceive likewise the name of arch. 
 
 An arch, when a cylinder pierces another of a greater dia- 
 tneter, is called cylindro-cylindric. The term cylindro is 
 applied to the cylinder of the greatest diameter, and the 
 term cylindric to the less. 
 
JBUIjlbINO 
 
 From 55 ito 554 
 
 n.78 
 
 y^cU iiStcdda 3c SizSsroTid 
 
AND MACHINIST. 541 
 
 If a cylinder intersect a sphere of greater diameter than 
 the cylinder, the arch is called a sphero- cylindric arch ; but 
 on the other hand, if a sphere pierce a cylinder of greater 
 diameter than the sphere, the arch is called a cylindro- sphe- 
 ric arch. 
 
 If a cylinder pierce a cone, so as to make a complete per- 
 foration through the eone, two complete arches will be 
 formed, called cmo- cylindric arches ; but, on the contrary, 
 if a cone pierce a cylinder, so that the concavity made by 
 the cone is a conic surface, the arch is called cylindro-conic 
 arch. 
 
 If, in a straight wall, there be a cylindric aperture con- 
 tinuing quite through it, two arches will be formed, called 
 piano- cylindric arches. 
 
 Every description of arch is, in a similar manner to 
 the above, denoted by the two preceding words ; the 
 fcrmer ending in o, signifying the principal vault, or sur- 
 face cut through ; and the latter in ic, signifying the de- 
 scription of the aperture which pierces or intersects the wall 
 or vault. . 
 
 When groins are introduced merely for use, they may be 
 built either of brick or stone; but, when introduced byway 
 of proportion or decoration, their beauty will depend on the 
 generating figures of the sides, the regularity of the sur- 
 face, and the acuteness of the angles, which should not be 
 obturided. In the best buildings, when durability and 
 elegance are equally required, they may be constructed of 
 wrought stone ; and, when elegance is wanted, at a trifling 
 expense, of plaster, supported by timber ribs. 
 
 In stone-cutting, a narrow surface formed by a point or 
 chisel, on the surface of a stone, so as to coincide with a 
 straight edge, is called a draught. 
 
 The formation of stone arches has always been considered 
 a most useful and important acquisition to the operative 
 mason ; in order, therefore, to remove any difficulties 
 which might arise in the construction of arches of different 
 descriptions, both in straight ana circular walls, we shall here 
 introduce a few examples, which, it is hoped, with careful 
 examination, will greatly facilitate a knowledge of some of 
 the most abstruse parts of the art. 
 
 Fig^. ,551, No. 1. To find the moulds necessary for the construction of 
 a semicircular arch, cutting- a straight wall obliquely. 
 
542 
 
 THE OPERATIVE MECHANIC 
 
 Let ABCDEFGH be tite plan of the arch ; IKLM the outer line; 
 and NOPQ the inner line on the elevation. 
 
 abode, on the elevation, shows the bevel of each joint or bed from the 
 face of the wall ; and abed e below, gives the mould for the same, where 
 xy on the elevation corresponds with x y ?tia. 
 
 The arch mould, fig. 551, No. 2, is applied on the face of the stone, 
 and on being applied to the parts of the plan, gives, of course, the beve 
 of each concave side of the stone with the face, that is K to O, on the ele- 
 vation. 
 
 Fig. 552. To find the mould for constructing a semicircular arch in a 
 circular wall. 
 
 No. 1 is the elevation of the arch; and No. 2 the plan of the bottom 
 bed from q to r. 
 
 « to 5 is what the arch gains on the circle from the bottom bed ko tol; 
 and cto d is the projection of the intrados to p, on the joint 1. p. 
 
 Nos. 2, 3, 4, are plans of the three arch-stones, 1, 2, 3, in the eleva- 
 tion ; and Nos. 5 and 6 are moulds to be applied to the beds of stones 
 1 and 2, in which s c equals s c in No. 2, and t w equals tw in No. 3. 
 
 In No. I, kip 0 is the arch or face mould. 
 
 When the reader is thoroughly proficient in the construc- 
 tion of arches, under given datas, as the circumstances of 
 the case may point out, he may proceed to investigate the 
 principles of spherical domes and groins. 
 
 Figs. 553 and 554 show the principles of developing the soffits of the 
 arches in the two preceding examples. In each the letters of reference 
 are alike, and the operation is precisely the same. 
 
 Let ABDE be the plan of the opening in the wall ; and AFB the 
 elevation of the arch: produce the chord AB to C, divide the semicircle 
 AFB into any number of parts, the more the better, and with the com- 
 passes set to any one of these divisions, run it as many times along AC 
 as the semicircle is divided into ; then draw lines, perpendicular to BC, 
 through every division in the semicircle and the line CA, and set the dis- 
 tance lb, 2 d, 3 f, &c. respectively equal to ab, c d, ef, &c.and then by 
 tracing a curve through these points, and finding the points in the line 
 GD, in the same manner, the soffit of the arch is complete. 
 
 Fig. 555, shows the method of constructing spherical domes. 
 
 No. 1 mould is applied on the spherical surface to the vertical joints ; 
 and No. 2 mould on the same surface to the other joints; and in both 
 cases, the mould tends to the centre of the dome. 
 
 3, 4, 5, 6, 7, and 8, are moulds which apply on the convex surface to 
 the horizontal joint, the lines ab, c d, ef, &c. being at right angles to 
 the different radii, b c, dc,fc, &c. and produced until they intersect 
 the perpendicular a c ; the different intersections are the centres which 
 give the circular leg of the mould, and the straight part gives the hori- 
 zontal joint. 
 
 Fig. 55G exhibits the plan of a groined vault. 
 
 Lay down the arch, either at the full or half size, on a floor or piece of 
 floor-cloth, then divide and draw on the plan the number of joints in the 
 semicircular arch, and from the intersections with the diagonals, draw the 
 transverse joints on the plan, and produce them till they touch the in- 
 triidoes of the elliptical arch, the curve of which may be found by setting 
 the corresponding distances from the line of the base to the curve ; thus 
 a b equal to a b. This being accomplished, draw the joints of the ellipti- 
 
BlTIOLBIING 
 From 556 to 551 
 
 f 
 
 FI. 7 9 
 
 556 
 
 hTa4U &.Stcddev scdbzStrVLZ 
 
! 
 
 ■i 
 
 
 I 
 
 I 
 
AND MACHINIST. 
 
 543 
 
 cal arch in the manner ot which we give e t/, as a specimen. To draw the 
 joint c d, draw the chord e c and bisect it, draw a line from the centre c, 
 through the bisecting point, and produce it till it touches the perpendicu- 
 lar e f; and c d, being at right angles to e f, will be the joint required. In 
 the same manner the others are found. 
 
 By examination, it will be seen, that a rectangle circumscribing the 
 mould 3, 3, gives the size of the stone in its square state, and, that if each 
 stone in both arches be thus enclosed, the dimensions for each will be 
 found, as also the position in which the moulds must be placed. The 
 dark lines give the different bevels which must be carefully prepared and 
 applied to the stones in the manner represented in the figure. 
 
 Fig. 557. To draw the joints of the stones for an elliptical arch in a 
 wall, &c. 
 
 The curve is here described by the intersection of lines, which, cer- 
 tainly, gives the most easy and pleasing curve, as segments of circles 
 apply only under certain data* or in the proportion which the axis major 
 has to the axis minor, while the intersection of lines apply to any descrip- 
 tion of ellipsis. Find the foci F. In an ellipsis the distance of either 
 focus from one extremity of the axis minor is equal to the semi-axis ma- 
 jor ; that is, DF is equal to c C. Then to find any joint, a b, draw lines 
 from both foci through the point 6, as F e, / d, and bisect the angle db e 
 by the line a 6, which is the joint required. 
 
 Having thus given a general outline of the principles of 
 masonry, and accompanied the same with a few examples 
 on the most abstruse parts of the art, we shall conclude 
 this part of our treatise with the methods employed in the 
 mensuration of masons" work. 
 
 Rough stone or marble is measured by the foot cube : but 
 in measuring for workmanship, the superficies or surface, 
 for plain work, is measured before it is sunk. In measuring 
 ashlar, one bed and one upright joint are taken and con- 
 sidered plain work. In taking the plain sunk, or cir- 
 cular work, and the straight moulded, or circular moulded 
 work, particular care is required to distinguish the different 
 kinds of work in the progress of preparing the stone. In 
 measuring strings, the weathering is denominated sunk 
 work^ and the grooving throatings. 
 
 Stone cills to windows, &c. are, in general, about 4| 
 inches thick and 8 inches broad, and are weathered at the 
 top, which reduces the front edge to about 4 inches, and the 
 horizontal surface at the top to about I J inch on the inside ; 
 so that the part taken away is 6§ inches broad and three 
 quarters of an inch deep. Cills, when placed in the wall, 
 generally project about inches. The horizontal part left 
 on the inside of the cill is denominated plain work; and 
 the sloping part sunk work ; and in the dimension book 
 are entered thus, — 
 
644 
 
 THE OPERATIVE MECHANIC 
 
 U 
 
 4 
 
 Si 
 
 8 inches the breadth of the plain work in the dll 
 according- to the above dimensions, — then 
 
 
 8 
 
 2 8 
 
 
 4 
 
 H 
 
 2 2 
 
 2 
 
 s 
 
 
 
 4 
 
 6 
 
 
 4 0 
 
 
 Plain work. 
 
 Sunk work. 
 
 Plain to ends 
 of throating-. 
 
 No account is taken of the sawing. 
 
 Cornices are measured by girthing round the moulded 
 parts, that is, the whole of the vertical and under parts, 
 called moulded work : — for example, suppose a cornice pro- 
 ject one foot, girth two feet, and is 40 feet in length, then 
 the dimensions will be entered as under, — 
 
 40 
 
 2 80 
 
 40 
 
 1 40 
 
 Moulded work. 
 Sunk work at top. 
 
 All the vertical joints must be added to the above. 
 
 Cylindrical work is measured in the girth ; and the sur- 
 face is calculated to be equivalent to plain work twice 
 taken. 
 
 For example, suppose it be required to measure the plain 
 work or a cylinder, 10 feet long, and 5 feet in circumference, 
 the dimensions would then be entered 
 
 ^5 0 Sup', plain work, double measure. 
 
 Paving-slabs and chimney-pieces are found by superficia. 
 measure, as also are stones under two inches thick. 
 
 The manner in which the dimensions of a house are 
 taken, vary according to the place and the nature of the 
 agreement. 
 
 In Scotland, and most parts of England, if the builder 
 engages only for workmanship, the dimensions are taken 
 round the outside of the house for the length, and the 
 height is taken for the width, and the two multiplied 
 
AND MACHINIST. 
 
 bio 
 
 together gives the superficial contents. This, however, 
 applies only when the wall is of the same thickness all the' 
 way up ; and when not, as many separate heights are taken 
 as there are thicknesses. This mode of measuring gives 
 something more than the truth, by the addition of the four 
 quoins, which are pillars of two feet square ; but this is not 
 more than considered sufficient to compensate the workmen 
 for the extra labour in plumbing the quoins. 
 
 If there be a plinth, string, course-cornice, or blocking 
 course, the height is taken from the bottom of the plinth 
 to the top of the blocking course, including the thickness of 
 the same ; that is, the measurer takes a line or tape and be 
 gins, we will suppose, at the plinth, then stretching the line 
 to the top, bends it into the offset, or weathering, and, 
 keeping the corner tight at the internal angle, stretches the 
 line vertically upon the face of the wall, from the internal 
 angle to the internal angle of the string ; then girths round 
 the string to the internal angle at the top of the string, and 
 keeping the line tight at the upper internal angle, stretches 
 it to meet the cornice ; he then bends it round all the 
 mouldings to the internal angle of the blocking course, 
 from which he stretches the string up to the blocking course, 
 to the farther extremity of the breadth of the top of the 
 same so that the extent of the line is the same as the 
 vertical section stretched out : this dimension is accounted 
 the height of the building. 
 
 With respect to the length, when there arc any pilasters, 
 breaks, or recesses, the girth of the whole is taken at the 
 length. This method is, perhaps, the most absurd of any 
 admitted in the art of measuring ; since this addition in 
 height and length, is not sufficient to compensate for the 
 value of the workmanship on the ornamental parts. 
 
 The value of a rood of workmanship must be first ob- 
 tained by estimation, that is, by finding the cost of each 
 kind of work, such as plinth, strings, cornices, and archi- 
 traves, &c. and adding to them the plain ashlar work, and 
 the value of the materials, the amount of which, divided 
 by the number of roods contained in the w^hole, give the 
 mean price of a single rood. When the apertures or open- 
 ings in a building are small, it is not customary to make 
 deductions either for the materials or workmanship which 
 are there deficient, as the trouble of plumbing and return- 
 ing the quoins, is considered equivalent tor the deficiency of 
 fliaterials occasioned by such aperture. 
 
546 
 
 THE OPERATIVE MECHANIC 
 
 Elsam’s Gentleman's and Builder’s Assistant^ gives the 
 following information on the practice of measuring rough 
 stone work. 
 
 To find the number of perches contained in a piece of 
 rough stone-work. 
 
 If the wall be at the standard thickness, that is, 12 inches high, IS 
 inches thick, and 21 feet long, divide the area by 21, and the quotient, if 
 any, will be the answer in perches, and the remainder, if any, is feet. 
 If the wall be more or less than 18 inches thick, multiply the area of the 
 wall by the number of inches in thickness, which product, divided by 18, 
 and that quotient by 21, will give the perches contained. 
 
 Exam^Ae, A piece of stone-work is 40 feet long, 20 feet high, and 24 
 inches thick, how many perches are contained in it? 
 
 40 length. 
 
 20 height. 
 
 800 
 
 24 
 
 3200 
 
 1600 
 
 21 ) 
 
 18) 19200 (1066 
 18 105 
 
 120 16 
 108 
 
 120 
 
 108 
 
 P. P. In. 
 
 ( 50 16 8 
 
 12 equal to 8 inches. 
 
 The method last described, of finding the value of mason’s 
 work, is usually adopted, the perch being the standard of 
 the country ; but the most expeditious way of ascertaining 
 the value, is to cube the contents of the wall, and to charge 
 the work at per foot. To ascertain the value of common 
 stone- work, a calculation should be made of the prime cost 
 of all the component parts, consisting of the stones in the 
 quarry, the expense of quarrying, land-carriage to the place 
 where it is to be used, with the extra trouble and consequent 
 expense in carrying the stone one, two, three, or more 
 stories higher. Also the price of the lime when delivered, to- 
 gether with the extra expense of wages to workmen, if in the 
 <’ountry ; all these circumstances must be taken into consi- 
 deration in finding the value of a perch of common stone- 
 work, the expense of which will be found to vary according to 
 
AND MACHINIST. 547 
 
 local circumstances, in degrees scarcely credible ; wherefore 
 a definite price cannot, with propriety, be fixed. 
 
 BRICKLAYING 
 
 In building upon an inclined plane, or rising ground, the 
 foundation must be made to rise in a series of level steps, 
 according to the general line of the ground, to insure a firm 
 bed for the courses, and prevent them from sliding ; for if 
 this mode be not adopted, the moisture in the foundations in 
 wet weather, will induce the inclined parts to descend, tc 
 the manifest danger of fracturing the walls and destroying 
 the building. 
 
 In walling, in dry w’eather, when the work is required to 
 be firm, the best mortar must be used ; and the bricks must 
 be wetted, or dipped in water, as they are laid, to cause 
 them to adhere to the mortar, which they would not do if 
 laid dry ; for the dry sandy nature of the brick absorbs the 
 moisture of the mortar and prevents adhesion. 
 
 In carrying up the wall, not more than four or five feet of 
 any part should be built at a time ; for, as all walls shrink im- 
 mediately after building, the part which is first carried up will 
 settle before the adjacent part is carried up to it, and, con- 
 sequently, the shrinking of the latter will cause the two 
 parts to separate ; therefore, no part of a wall should be 
 carried higher than one scaffold, without having its contin- 
 gent parts added to it. In carrying up any particular part, 
 the ends should be regularly sloped off, to receive the bond 
 of the adjoining parts on the right and left. 
 
 There are two descriptions of bonds ; English bond, and 
 Flemish bond. In the English bond, a row of bricks is laid 
 lengthwise on the length of the wall, and is crossed by ano- 
 ther row, which has its length in the breadth of the Avail, 
 and so on alternately. Those courses in which the lengths 
 of the bricks are disposed through the length of the wall, 
 are termed stretching courses, and the bricks stretchers : and 
 those courses in which the bricks run in the thickness of 
 the lengths of the walls, heading courses, and the bricks 
 headers. 
 
 ITie other description of bond, called Flemish bond, con- 
 sists in placing a header and a stretcher alternately in the 
 same course. The latter is deemed the neatest, and most 
 elegant ; but, in the execution is attended with great incon- 
 venience, and, in most cases, does not unite the parts of a 
 
548 
 
 THE OPERATIVE MECHANIC 
 
 wall with tne same degree of firmness as the English bond. 
 In general, it may be observed, that, whatever advantages 
 are gained by the English bond in tying a wall together in 
 its thickness, they are lost in the longitudinal bond ; and 
 vice-versa. To remove this inconvenience, in thick walls, 
 some builders place the bricks in the cone at an angle of 
 forty-five degrees, parallel to each other, throughout the 
 length of every course, but reversed in the alternate 
 courses ; so that the bricks cross each other at right an- 
 gles. But even here, though the bricks in the cone have 
 sufficient bond, the sides are very imperfectly tied, on ac- 
 count of the triangular interstices formed by the oblique 
 direction of the internal bricks against the flat edges of those 
 in the outside. 
 
 Concerning the English bond, it may be observed, that, 
 as the longitudinal extent of a brick is nine inches, and its 
 breadth four and a half, to prevent two vertical joints from 
 running over each other at the end of the first stretcher 
 from the corner, it is usual, after placing the return corner 
 stretcher, which occupies half of the length of this stretcher, 
 and becomes a header in the face, as the stretcher is bj- 
 low, to place a quarter brick on the side, so that the two 
 together extend six inches and three-quarters, being a lap 
 of two inches and a half for the next header. The bat thus 
 introduced is called a closer. A similar effect may be ob- 
 tained by introducing a three-quarter bat at the corner of 
 the stretching course, so that the corner header being laid 
 over it, a lap of two inches and a quarter will be left, at 
 the end of the stretchers below, for the next header, which 
 being laid on the joint below the stretchers, will coincide 
 with its middle. 
 
 In the winter, it is very essential to keep the unfinished 
 wall from the alternate effects of rain and frost for if it is 
 exposed, the rain will penetrate into the bricks and mortar, 
 and, by being converted into ice, expand, and burst or 
 crumble the materials in which it is contained. 
 
 The decay of buildings, so commonly attributed to the 
 effects of time, is, in fact, attributable to this source ; but 
 as finished edifices have only a vertical surface, the action 
 and counter-action of the rain and frost extend not so ra- 
 pidly as in an unfinished wall, where the horizontal sur- 
 face permits the rain and frost to have easy access into the 
 body of the work. Great care, therefore, must be taken as 
 soon as the frost or stormy weather sets in, to cover the iwi- 
 
AND MACHINIST. 549 
 
 finished walls, either with straw, which is the most com- 
 mon, or weather boarding. 
 
 When weather boarding is employed, it is advisable to 
 have a good layer of straw between the work and the board- 
 ing, and to place the boarding in the form of stone-coping, 
 to throw the water off equally on both sides. 
 
 A number of very pleasing cornices and other ornaments 
 may be formed in brick-work, by the mere disposition of 
 the bricks, Avithout cutting ; and if cut, a simple chainpher 
 will be sufficient. A great defect, however, is very often 
 observable in these ornaments, particularly in the bulging 
 of arches over windows ; which arises from mere careless- 
 ness, in rubbing the bricks too much on the inside ; where- 
 as, if due care Avere taken to rub them exact to the gauge, 
 their geometrical bearings being united, they Avould all tend 
 to one centre, and produce a Avell- proportioned and pleasing 
 effect. 
 
 In steining Avells, it is necessary first to make a centre, 
 consisting of a boarding of inch or inch and a half stuff, 
 ledged within with three circular rings, upon which the bricks, 
 all headers, are laid. The vacuity betAveen the bricks towards 
 the boarding, are to be filled in with tile or other pieces of 
 brick. As the w^ell-sinker proceeds to excavate the ground, 
 the centre with its load of bricks sinks, and another similarly 
 charged is laid upon it, and another upon that, and so on till 
 the wall is complete, the centreing remaining with the 
 brick- work. This plan is generally adopted in London, at 
 least where the soil is sandy and loose ; where it is firm, 
 centreings are not requisite. In the country, among many 
 other methods, the following is most approved : — rings 
 of timber, without the exterior boarding, are used ; upon the 
 first ring, four or five feet of bricks are laid, then a second 
 ring, and so on. But the mode before described is by far 
 the most preferable ; as in the latter the sides of the brick- 
 work are apt to bulge in sinking, particularly if great care be 
 not taken in filling and ramming the sides uniformly, so as 
 to keep the pressure regular and equal. In steining wells 
 and building cesspools, a rod of brick-work will require at 
 least 4760 bricks. 
 
 As the construction of AA^alls, arches, groins, &c. in 
 brick-work, approximates so nearly to that of stone-Avork, i 
 and as the same observations generally apply, further infor- 
 mation would, perhaps, be considered superfluous ; we 
 shall, therefore, conclude this article with some practical 
 observations on the measuring of brick-AVork. 
 
550 
 
 THE OPERATIVE MECHANIC 
 
 Brick-work is measured and valued by the rod. The con- 
 tents of a rod of brick-work is 16^ feet simarc ; consequent- 
 ly, the superficial rod contains 2/2*25, or 272J square 
 feet; but as the quarter has been found troublesome in cal- 
 culation, 2/2 superficial feet has been admitted as the 
 standard. 
 
 The standard thickness of a brick wall is brick laid 
 lengthwise ; therefore, if 272 square feet be multiplied by 
 13 inches, the result will be 306 cubic feet, or a rod. 
 
 A rod of standard brick-work, making the necessary allovr- 
 ance for mortar and waste, will require 4500 bricks ; but 
 this quantity is of course ruled by the size of the brick, and 
 the closeness of the joints. 
 
 A foot of reduced brick-work requires 17 bricks ; a foot 
 superficial of marl facing, laid in Flemish bond, 8 bricks ; 
 and a foot superficial of gauged arches, 10 bricks. In paving, 
 a yard will require 82 jiaving bricks, or 48 stock bricks, or 
 38 bricks laid flat. 
 
 A square of tiling contains 100 superficial feet ; and re- 
 quires of plain tiles, 800 at -a six-inch gauge, 700 at a seven- 
 inch gauge, or 600 at an eight- inch gauge. 
 
 The distances between the respective laths must depend 
 on the pitch of the roof ; and one roof may require a 6, 
 7, and 8 inch gauge. For instance, akirt roof will require, 
 in the kirt part, a 74 or 8 inch gauge, and in the upper part 
 6, 64, or 7 inch, the gauge decreasing in the ratio of the 
 angle of elevation. 
 
 A square of plain tiling will require a bundle of laths, 
 more or less, according to the pitch; with two bushels of 
 lime, one bushel of sand, and a peck of tile- pins. 
 
 Laths are sold by the thousand, or bundle ; and each 
 bundle is supposed to contain 100 laths, though the exact 
 number depends on the length ; the 3 feet containing 5 
 score, the 4 feet 4 score, the 5 feet 3 score, and so on in 
 proportion. 
 
 A square of pan -tiling requires 180 tiles, laid at a ten- 
 inch gauge ; and one bundle, containing 12 laths, ten feet 
 long. 
 
 In lime measure, 25 struck bushels, or 100 pecks, make a 
 hundred of lime ; 8 gallons, a bushel dry measure ; and 268 
 cubic inches, one gallon. 
 
 In measuring sand, 24 heaped, or 30 struck bushels make 
 one load ; and 24 cubic feet weighs one ton. 
 
 A load of mortar, which ought to contain half a hundred ot 
 lime, with a proportionate quantity of sand, is 27 cubic feet. 
 
AND MACHINIST. 
 
 551 
 
 Excavations of the earth are measured by the number ot 
 cubic yards which they contain, therefore, to find the number 
 of cubic yards in a trench, find the solidity of the trench in 
 cubic feet, and divide it by 27 , the number of cubic feet in 
 a yard, and the quotient, is the number of cubic yards, and 
 the remainder the number of cubic feet. 
 
 For example, the length of a trench is 60 feet, the depth 3 feet, and 
 the breadth 2 feet. 
 
 60 
 
 3 
 
 180 
 
 2 
 
 yds, ft. 
 
 27 ) 360 ( 13 9 the answer. 
 
 27 
 
 90 
 
 81 
 
 9 
 
 In the horizontal dimensions, if the trench be wider at the 
 top than it is at the bottom, and equal at the ends, take 
 half the sum of the two dimensions for a mean breadth ; 
 and if the breadth of one end of the trench exceed that of 
 the other, so as to have two mean breadths, differing from 
 each other, take half the sum of the two added together, as 
 a mean breadth of the whole.' 
 
 In measuring the footing of a wall, multiply the length 
 and the height of the courses together ; then multiply 
 the product by the number of half bricks in the mean 
 breadth, divide the last product by 3, and the quotient is 
 the answer in reduced feet. Instead of measuring the 
 height of the footing, it is customary to allow three inches 
 to each course in height, or multiply the number of courses 
 by 3, which gives the height in inches. 
 
 To find the contents in rods of a piece of brick work. 
 
 Case 1. If the wall be of the standard thickness, divide the area of tlie 
 wall by 272, and the quotient is the number of rods, and the remainder 
 the number of feet ; but if the wall be either more or less than a brick 
 and a half in thickness, multiply the area of the 'wall by the number of 
 half bricks, that is, the number of half lengths of a brick ; divide the 
 product by 3, Avhich will reduce the wall to the standard thickness of 1^ 
 brick, then divide the quotient by 272, and it vvill give the number of rods, 
 
 Case II. Divide the number of cubic feet contained in the wall by 303 ; 
 the quotient will give the number of rods, and the remainder the number 
 of cubic feet. 
 
 Case III. Multiply the numter of cubic feet in a wall by 8 ; divide the 
 
THE OPERATIVE MECHANIC 
 
 552 
 
 product by 9 ; and the quotient will give the area of the wall at the 
 standard : divide this standard area by 272, and the quotient will give 
 the number of rods ; the remainder the reduced feet. 
 
 Example. The length of a wall is 0 feet, the height 20 feet, and the 
 thickness equal to the length of three bricks ; it is therefore required 
 to know how many rods of brick-work is contained in the said wall ? 
 
 Bv Case I. 60 
 
 20 
 
 1200 
 
 6 
 
 3 ) 7200 
 
 272 ) 2400 ( 8 rods 224 feet the answer. 
 
 2176 
 
 224 
 
 Case il 60 
 
 20 
 
 1200 
 
 2.3 thickness of wall 
 
 2100 
 
 300 
 
 303 ) 2700 ( 8 rods 252 feet the answer, 
 2448 
 
 252 
 
 Case III. 60 
 20 
 
 1200 
 
 2.3 
 
 2400 
 
 300 
 
 2700 
 
 8 
 
 9 ) 21600 
 
 272 ) 2400 ( 8 rods 224 feet, as in Case I 
 2176 
 
AND MACHINIST. 
 
 553 
 
 In the calculation of brick-work, where there are several 
 walls of different thicknesses, it will be quite unnecessary 
 to use the divisors 3 and 272, as will be hereafter shown. 
 
 In taking dimensions for workmanship, it is usual to 
 allow the length of each wall on the external side, to com- 
 pensate for plumbing the angles ; but this practice must not 
 be resorted to for labour and materials, as it gives too much 
 quantity in the height of the building or story by two pil- 
 lars of brick ; and in the horizontal dimensions by the 
 thickness of the walls. 
 
 In measuring walls, faced with bricks of a superior qua- 
 lity, most surveyors measure the whole as common work, 
 and allow an additional price per rod for the facing, as the 
 superior excellence of the work, and quality of the bricks 
 may deserve. 
 
 Every recess or aperture made in any of the faces must 
 be deducted ; but an allowance per foot lineal should be 
 made upon every right angle, whether external or internal, 
 excepting when two external angles may be formed by a 
 brick in breadth, and then only one of them must be al- 
 lowed . 
 
 Gauged arches are sometimes deducted and charged se- 
 parate ; but as the extra price must be allowed in the for- 
 mer case, it will amount to the same thing. 
 
 In measuring walls containing chimneys, it is not custom- 
 ary to deduct the flues ; but this practice, so far as re- 
 gards the materials, is unjust, though, perhaps, by taking 
 the labour and materials together, the overcharge, with 
 respect to the quantity of bricks and mortar, may, in some 
 degree, compensate for the loss of time : on the other hand, 
 if the proprietor finds the materials, it is not customary to 
 allow for the trouble of forming the flues, which, conse- 
 quently, is a loss to the contractor who has engaged by 
 task-work or measure. 
 
 If the breast of a chimney project from the face of the 
 wall, and is parallel to it, the best method is, to take the 
 horizontal and vertical dimensions of the face, multiply them 
 together, and multiply the product by the thickness, taken 
 in the thinnest part, without noticing the breast of the 
 chimney; then find the solidity of the breast itself, add 
 these solidities together, and the sum will give the solidity of 
 the wall, including the vacuities, which must be deducted 
 for the real solidity. Nothing more is necessary to be said 
 of the shaft, than to take its dimensions in height, breadth, 
 and thickness, in order to ascertain its solidity. 
 
554 THE OPERATIVE MECHANIC 
 
 If a chimney be placed at an angle, with the face of tne, 
 breast intersecting the two sides of the wall, the breast of 
 the chimney must be considered a triangular prism. To 
 take the dimensions : — -from the intersections of the front of 
 the breast into the two adjacent walls, draw two lines on 
 the floor, parallel to each adjacent wall ; then the triangle 
 on the floor, included between the front and these lines, will 
 be equal to the triangle on which the chimney stands, and, 
 consequently, equal to the area of the base. To attain the 
 area of the triangular base, the dimensions may be taken in 
 three various ways, almost equally easy ; one of which is, 
 to take the extent of the base, which is the horizontal di- 
 mension of the breast, and multiply it by half of the per- 
 pendicular ; or multiply the whole perpendicular by half 
 the base : but, as this calculation would, in cases of odd 
 numbers, run somewhat long, a more preferable method is, 
 to multiply the whole base by the whole perpendicular, and 
 take half of the product, which will give the area on which 
 the chimney stands ; and which, multiplied by the height, 
 gives the solid contents of the chimney. From this contents 
 is to be deducted the vacuity for the fire-place. 
 
 A row of plain tiles, laid edge to edge, with their broad 
 surfaces parallel to the termination of a wall, so as to pro- 
 ject over the wall at right angles to the vertical surface, is 
 called single plam tile creasing ; and two rows, laid one 
 above the other, the one row breaking the joints of the 
 other, arc called double plain tile creasing. 
 
 Over the plain tile creasing a row of bricks is placed 
 on edge, with their length in the thickness of the wall, and 
 are called a barge course^ or cope. 
 
 The bricks in gables, which terminate with plain tile 
 creasing coped with bricks, in order to form the sloping bed 
 for the ])lain tile creasing, must be cut, and the sloping of 
 the bricks thus, is called cut splay. 
 
 Plaiii tile creasing and cut splay are charged by the foot 
 run ; and the latter is sometimes charged by the superficial 
 foot. 
 
 A brick wall built in pannels between timber quarters is 
 called brick 7iogging ; and is generally measured by the yard 
 s(piarc, the quarters and nogging pieces being included in 
 the measure. 
 
 Pointing is the filling up the joints of the bricks after the 
 walls arc'built. It consists in raking out some of the mor- 
 tar from the joints, and filling them again with blue mor- 
 tar, and in one kind of pointing, the courses are simnlv 
 
AND MACHINIST. 
 
 655 
 
 marked with the end of a trowel, called flat-joint pointing ; 
 but if, in addition to flat -joint pointing, plaster be inserted 
 in the joint with a regular projection, and neatly paved to 
 a parallel breadth, it is termed hick pointing, or hick- joint 
 pointing, or formerly, hick, and patt. Pointing is measured 
 by the foot superficial, including in the price, mortar, labour, 
 and scaffolding. 
 
 Rubbed and gauged work is set in putty or mortar ; and 
 is measured either by the foot superficial, or the foot run, 
 according to the manner in which it is constructed. 
 
 In measuring canted bow windows, the sides are con- 
 sidered as continued straight lines ; but the angles on the 
 exterior side of the building, whether they be external or 
 internal, are allowed for in addition, and paid for under the 
 denomination of run of bird’s mouth. All angles within the 
 building, if oblique, from whatever cause they are made, 
 either by straight or circular bows, or the splays of windows, 
 are allowed for, under the head Oi run of cut splay. 
 
 Brick cornices are measured by the leiical foot ; but as 
 various kinds of cornices require more or less difficulty in 
 the execution, the price must depend on the labour and the 
 value of the material used. 
 
 Garden walls are measured the same as other walls, but if 
 interrupted by piers, the thin part may be measured as in 
 common walling, and the piers by themselves, making an 
 allowance, at per foot run, for the right angles The coping 
 is measured by itself, according to the kind employed. 
 
 Paving is laid either with bricks, or tiles, and is measured 
 by the yard square. The price, per yard, is regulated by the 
 manner in which the bricks or tiles are laid, whether flat or 
 edge-ways, or whether any of them be laid in sand or mortar. 
 
 The circular parts of drains may be reduced either to the 
 standard, or the cubic foot ; and the number of rods may, if 
 required, be taken. The mean dimensions of the arch 
 may be found, by taking the half sum of the exterior and in- 
 terior circumferences ; but, perhaps, it were better to make 
 the price of the common measure, whether it be a foot, 
 yard, or rod, greater as the diameter is less ; but as the re- 
 ciprocal ratio would increase the price too much in small 
 diameters, perhaps prices at certain diameters would be a 
 sufficient regulation. 
 
 The following tables will be found an acquisition to <hose 
 persons to whom a saving of time is an object: — 
 
556 
 
 THE OPERATIVE MECHANIC 
 
 TABLE I. 
 
 This Table shews what quantity of bricks are necessary to construct a 
 piece of brick-work of any given dimensions, from half a brick to two 
 bricks and a half in thickness ; and by which the number for any tliick- 
 ness may be found. 
 
 This Table is at the rate of 4500 bricks to the rod of reduced brick- 
 work, including waste. 
 
 Area of 
 
 The number of bricks thick and the quantity required. 
 
 the face 
 
 
 
 
 
 
 of wall. 
 
 J brick. 
 
 1 brick. 
 
 li brick. 
 
 2 bricks. 
 
 2J bricks. 
 
 1 
 
 5 
 
 1 1 
 
 16 
 
 22 
 
 27 
 
 2 
 
 11 
 
 22 
 
 33 
 
 44 
 
 55 
 
 3 
 
 16 
 
 33 
 
 49 
 
 66 
 
 82 
 
 4 
 
 22 
 
 44 
 
 66 
 
 88 
 
 no 
 
 5 
 
 27 
 
 55 
 
 82 
 
 no 
 
 137 
 
 6 
 
 S3 
 
 66 
 
 99 
 
 132 
 
 165 
 
 7 
 
 38 
 
 77 
 
 115 
 
 154 
 
 193 
 
 8 
 
 44 
 
 88 
 
 132 
 
 176 
 
 220 
 
 9 
 
 49 
 
 99 
 
 148 
 
 198 
 
 288 
 
 10 
 
 55 
 
 no 
 
 165 
 
 220 
 
 275 
 
 20 
 
 1 10 
 
 220 
 
 330 
 
 441 
 
 551 
 
 SO 
 
 165 
 
 330 
 
 496 
 
 661 
 
 827 
 
 40 
 
 220 
 
 441 
 
 661 
 
 882 
 
 1102 
 
 50 
 
 275 
 
 551 
 
 827 
 
 1102 
 
 1378 
 
 60 
 
 330 
 
 661 
 
 992 
 
 1323 
 
 1655 
 
 70 
 
 386 
 
 772 
 
 1158 
 
 1544 
 
 1930 
 
 80 
 
 441 
 
 882 
 
 1323 
 
 1764 
 
 2205 
 
 90 
 
 496 
 
 992 
 
 1488 
 
 1985 
 
 2480 
 
 100 
 
 551 
 
 1102 
 
 1654 
 
 2205 
 
 2757 
 
 200 
 
 1102 
 
 2205 
 
 3308 
 
 4411 
 
 5514 
 
 300 
 
 1654 
 
 3308 
 
 4963 
 
 6617 
 
 8272 
 
 400 
 
 2205 
 
 4411 
 
 6617 
 
 8823 
 
 n,029 
 
 500 
 
 2757 
 
 5514 
 
 8272 
 
 11,029 
 
 13,786 
 
 600 
 
 3308 
 
 6617 
 
 9926 
 
 13,235 
 
 16,544 
 
 700 
 
 3860 
 
 7720 
 
 11,580 
 
 15,441 
 
 19,301 
 
 800 
 
 4411 
 
 8823 
 
 13,235 
 
 17,647 
 
 22,058 
 
 900 
 
 4963 
 
 9926 
 
 14,889 
 
 19,852 
 
 24,816 
 
 1000 
 
 5514 
 
 11,029 
 
 16,544 
 
 22,058 
 
 27,573 
 
 2000 
 
 11,029 
 
 22,058 
 
 33,088 
 
 44,117 
 
 55,147 
 
 3000 
 
 16,544 
 
 33,088 
 
 49,632 
 
 66,176 
 
 82,720 
 
 4000 
 
 22,058 
 
 44,117 
 
 66,176 
 
 88,235 
 
 110,294 
 
 5000 
 
 27,573 
 
 55,147 
 
 82,720 
 
 110,294 
 
 137,867 
 
 6000 
 
 33,088 
 
 66,176 
 
 99,264 
 
 132,352 
 
 165,441 
 
 7000 
 
 38,602 
 
 77,205 
 
 1 15,808 
 
 154,411 
 
 193,014 
 
 8000 
 
 44,117 
 
 88,235 
 
 132,352 
 
 176,470 
 
 220,588 
 
 9000 
 
 49,632 
 
 99,264 
 
 148,896 
 
 198,529 
 
 248,161 
 
 10,000 
 
 55,147 
 
 110,294 
 
 165,441 
 
 220,588 
 
 275.735 
 
 20,000 
 
 110,294 
 
 220.588 
 
 330,882 
 
 441,176 
 
 551,470 
 
 10,000 
 
 165,441 
 
 330,882 
 
 496,323 
 
 661,764 
 
 827,205 
 
 40,000 
 
 220,588 
 
 441,176 
 
 661,764 
 
 882,352 
 
 1,102,940 
 
 50,000 
 
 275,735 
 
 551,470 
 
 827,205 
 
 1,102,940 
 
 1,378,675 
 
 60,000 
 
 330,882 
 
 661,764 
 
 992,646 
 
 1,323,528 
 
 1,654,410 
 
 70,000 
 
 386,029 
 
 772,058 
 
 1,158,087 
 
 1,544,116 
 
 1,930,145 
 
 80,000 
 
 441,176 
 
 882,352 
 
 1,323,528 
 
 1,764,704 
 
 2,205,880 
 
 90,000 
 
 496,323 
 
 992,646 
 
 1,488,969 
 
 1,985,292 
 
 2,481,615 
 
AND Machinist, 
 
 557 
 
 The left-hand column contains the number of superficial 
 feet contained in the wall to be built : the adjacent columns 
 shew the number of bricks required to build a wall of the 
 different thicknesses of ^ 1,11, 2, and 2| bricks. 
 
 Example. Suppose it be required to find the number of bricks neces- 
 sary to build a wall 1 brick thick, containing" an area of 5760 feet ? 
 First look for 5000 in the left hand column, and you will find that it takes 
 55,147 bricks, add to this quantity, the number necessary for each of the 
 other component parts, and we shall have the following 
 5000 will require 55147 
 700 .... 7720 
 
 60 . . . . ■ 661 
 
 5760 63,528 
 
 TABLE II. 
 
 Shews the number of rods contained in any number of superficial feet, 
 from 1 to 10,000, and from ^ a brick to 2^ bricks ; and thence by addi- 
 tion, to any number, and to any thickness, at the rate of 4500 bricks to 
 the rod. 
 
 Feet 
 
 sup. 
 
 § brick. 
 
 1 
 
 brick. 
 
 1 
 
 .] brick. 
 
 2 
 
 bricks. 
 
 24 bricks. 
 
 
 R. 
 
 Q 
 
 ,F. 
 
 In. 
 
 R. 
 
 Q 
 
 .F. 
 
 In. 
 
 R. 
 
 Q 
 
 .F. 
 
 In. 
 
 R. 
 
 Q 
 
 .F. 
 
 In. 
 
 R. 
 
 Q. 
 
 .F. 
 
 In. 
 
 1 
 
 0 
 
 0 
 
 0 
 
 4 
 
 0 
 
 0 
 
 0 
 
 8 
 
 0 
 
 0 
 
 1 
 
 O' 
 
 0 
 
 0 
 
 1 
 
 4 
 
 0 
 
 0 
 
 1 
 
 8 
 
 2 
 
 0 
 
 0 
 
 0 
 
 8 
 
 0 
 
 0 
 
 1 
 
 4 
 
 0 
 
 0 
 
 2 
 
 0 
 
 0 
 
 0 
 
 2 
 
 8 
 
 0 
 
 0 
 
 3 
 
 4 
 
 3 
 
 0 
 
 0 
 
 1 
 
 0 
 
 0 
 
 0 
 
 2 
 
 0 
 
 0 
 
 0 
 
 S 
 
 0 
 
 0 
 
 0 
 
 4 
 
 0 
 
 0 
 
 0 
 
 5 
 
 0 
 
 4 
 
 0 
 
 0 
 
 1 
 
 4 
 
 0 
 
 0 
 
 2 
 
 8 
 
 0 
 
 0 
 
 4 
 
 0 
 
 0 
 
 0 
 
 5 
 
 4 
 
 0 
 
 0 
 
 6 
 
 8 
 
 5 
 
 0 
 
 0 
 
 1 
 
 8 
 
 0 
 
 0 
 
 3 
 
 4 
 
 0 
 
 0 
 
 5 
 
 0 
 
 0 
 
 0 
 
 6 
 
 8 
 
 0 
 
 0 
 
 8 
 
 4 
 
 6 
 
 0 
 
 0 
 
 2 
 
 0 
 
 0 
 
 0 
 
 4 
 
 0 
 
 0 
 
 0 
 
 6 
 
 0 
 
 0 
 
 0 
 
 8 
 
 0 
 
 0 
 
 0 
 
 10 
 
 0 
 
 7 
 
 0 
 
 0 
 
 2 
 
 4 
 
 0 
 
 0 
 
 4 
 
 8 
 
 0 
 
 0 
 
 7 
 
 0 
 
 0 
 
 0 
 
 9 
 
 4 
 
 0 
 
 0 
 
 11 
 
 8 
 
 8 
 
 0 
 
 0 
 
 2 
 
 8 
 
 0 
 
 0 
 
 5 
 
 4 
 
 0 
 
 0 
 
 8 
 
 0 
 
 0 
 
 0 
 
 10 
 
 8 
 
 0 
 
 0 
 
 13 
 
 4 
 
 9 
 
 0 
 
 0 
 
 3 
 
 0 
 
 0 
 
 0 
 
 6 
 
 0 
 
 0 
 
 0 
 
 9 
 
 0 
 
 0 
 
 0 
 
 12 
 
 0 
 
 0 
 
 0 
 
 15 
 
 0 
 
 10 
 
 0 
 
 0 
 
 3 
 
 4 
 
 0 
 
 0 
 
 6 
 
 8 
 
 0 
 
 0 
 
 10 
 
 0 
 
 9 
 
 6 
 
 13 
 
 4 
 
 0 
 
 0 
 
 16 
 
 8 
 
 11 
 
 0 
 
 0 
 
 3 
 
 8 
 
 0 
 
 0 
 
 7 
 
 4 
 
 0 
 
 0 
 
 11 
 
 0 
 
 0 
 
 0 
 
 14 
 
 8 
 
 0 
 
 0 
 
 18 
 
 4 
 
 12 
 
 0 
 
 0 
 
 4 
 
 0 
 
 0 
 
 0 
 
 8 
 
 0 
 
 0 
 
 0 
 
 12 
 
 0 
 
 0 
 
 0 
 
 16 
 
 0 
 
 0 
 
 0 
 
 20 
 
 0 
 
 13 
 
 0 
 
 0 
 
 4 
 
 4 
 
 0 
 
 0 
 
 8 
 
 8 
 
 9 
 
 0 
 
 13 
 
 0 
 
 0 
 
 0 
 
 17 
 
 4 
 
 0 
 
 0 
 
 21 
 
 8 
 
 14 
 
 0 
 
 0 
 
 4 
 
 8 
 
 0 
 
 0 
 
 9 
 
 4 
 
 0 
 
 0 
 
 14 
 
 0 
 
 0 
 
 0 
 
 18 
 
 8 
 
 0 
 
 0 
 
 23 
 
 4 
 
 15 
 
 0 
 
 0 
 
 5 
 
 0 
 
 0 
 
 0 
 
 10 
 
 0 
 
 0 
 
 0 
 
 15 
 
 0 
 
 0 
 
 0 
 
 20 
 
 0 
 
 0 
 
 0 
 
 25 
 
 0 
 
 16 
 
 0 
 
 0 
 
 5 
 
 4 
 
 0 
 
 0 
 
 10 
 
 8 
 
 0 
 
 0 
 
 16 
 
 0 
 
 0 
 
 0 
 
 21 
 
 4 
 
 0 
 
 0 
 
 26 
 
 8 
 
 17 
 
 0 
 
 0 
 
 5 
 
 8 
 
 0 
 
 0 
 
 11 
 
 4 
 
 0 
 
 0 
 
 17 
 
 0 
 
 •0 
 
 0 
 
 22 
 
 8 
 
 0 
 
 0 
 
 28 
 
 4 
 
 18 
 
 0 
 
 0 
 
 6 
 
 0 
 
 0 
 
 0 
 
 12 
 
 0 
 
 0 
 
 0 
 
 18 
 
 0 
 
 0 
 
 0 
 
 24 
 
 0 
 
 0 
 
 0 
 
 SO 
 
 0 
 
 19 
 
 0 
 
 0 
 
 6 
 
 4 
 
 0 
 
 0 
 
 12 
 
 8 
 
 0 
 
 0 
 
 19 
 
 0 
 
 0 
 
 0 
 
 25 
 
 4 
 
 0 
 
 0 
 
 31 
 
 8 
 
 20 
 
 0 
 
 0 
 
 6 
 
 8 
 
 0 
 
 0 
 
 13 
 
 4 '■ 
 
 0 
 
 0 
 
 20 
 
 0 
 
 0 
 
 0 
 
 26 
 
 8 
 
 0 
 
 0 
 
 S3 
 
 4 
 
 21 
 
 0 
 
 0 
 
 7 
 
 0 
 
 0 
 
 0 
 
 14 
 
 0 
 
 0 
 
 0 
 
 21 
 
 0 
 
 0 
 
 0 
 
 28 
 
 0 
 
 0 
 
 0 
 
 35 
 
 0 
 
 22 
 
 0 
 
 0 
 
 7 
 
 4 
 
 0 
 
 0 
 
 14 
 
 8 
 
 0 
 
 0 
 
 22 
 
 0 
 
 0 
 
 0 
 
 29 
 
 4 
 
 0 
 
 0 
 
 36 
 
 8 
 
 23 
 
 0 
 
 0 
 
 7 
 
 8 
 
 0 
 
 0 
 
 15 
 
 4 
 
 0 
 
 0 
 
 23 
 
 0 
 
 0 
 
 0 
 
 30 
 
 8 
 
 0 
 
 0 
 
 38 
 
 4 
 
 24 
 
 0 
 
 0 
 
 8 
 
 0 
 
 0 
 
 0 
 
 16 
 
 0 
 
 0 
 
 0 
 
 24 
 
 0 
 
 0 
 
 0 
 
 32 
 
 0 
 
 0 
 
 0 
 
 40 
 
 0 
 
 25 
 
 0 
 
 0 
 
 8 
 
 4 
 
 0 
 
 0 
 
 16 
 
 8 
 
 0 
 
 0 
 
 25 
 
 0 
 
 0 
 
 0 
 
 33 
 
 4 
 
 0 
 
 0 
 
 41 
 
 8 
 
 26 
 
 0 
 
 0 
 
 8 
 
 8 
 
 0 
 
 0 
 
 17 
 
 4 
 
 0 
 
 0 
 
 26 
 
 0 
 
 0 
 
 0 
 
 34 
 
 8 
 
 0 
 
 0 
 
 43 
 
 4 
 
 27 
 
 0 
 
 0 
 
 9 
 
 0 
 
 0 
 
 0 
 
 18 
 
 0 
 
 0 
 
 0 
 
 27 
 
 0 
 
 0 
 
 0 
 
 36 
 
 0 
 
 0 
 
 0 
 
 45 
 
 0 
 
 28 
 
 0 
 
 0 
 
 9 
 
 4 
 
 0 
 
 0 
 
 18 
 
 8 
 
 0 
 
 0 
 
 28 
 
 0 
 
 0 
 
 0 
 
 37 
 
 4 
 
 0 
 
 0 
 
 46 
 
 8 
 
 29 
 
 0 
 
 0 
 
 9 
 
 8 
 
 0 
 
 0 
 
 19 
 
 4 
 
 0 
 
 0 
 
 29 
 
 0 
 
 0 
 
 0 
 
 38 
 
 8 
 
 0 
 
 0 
 
 48 
 
 4 
 
 30 
 
 0 
 
 0 
 
 10 
 
 0 
 
 0 
 
 0 
 
 20 
 
 0 
 
 0 
 
 0 
 
 SO 
 
 0 
 
 0 
 
 0 
 
 40 
 
 0 
 
 0 
 
 0 
 
 50 
 
 0 
 
 31 
 
 0 
 
 0 
 
 10 
 
 4 
 
 0 
 
 0 
 
 20 
 
 8 
 
 0 
 
 0 
 
 31 
 
 0 
 
 0 
 
 0 
 
 41 
 
 4 
 
 0 
 
 0 
 
 51 
 
 8 
 
658 
 
 THE OPERATIVE MECHANIC 
 
 Feet 
 
 sup. 
 
 3 
 
 brick. 
 
 1 brick 
 
 
 brick. 
 
 2 
 
 bricks. 
 
 2^ bricks. 
 
 
 R. 
 
 Q 
 
 F. 
 
 In. 
 
 R.Q. 
 
 F. 
 
 In. 
 
 R. 
 
 Q 
 
 .F. 
 
 In. 
 
 R. 
 
 Q 
 
 :.F. 
 
 In. 
 
 R. 
 
 Q 
 
 l.F. 
 
 In. 
 
 S2 
 
 0 
 
 0 
 
 10 
 
 8 
 
 0 
 
 0 
 
 21 
 
 4 
 
 0 
 
 0 
 
 32 
 
 0 
 
 0 
 
 0 
 
 42 
 
 8 
 
 0 
 
 0 
 
 53 
 
 4 
 
 S3 
 
 0 
 
 0 
 
 11 
 
 0 
 
 0 
 
 0 
 
 22 
 
 0 
 
 0 
 
 0 
 
 33 
 
 0 
 
 0 
 
 0 
 
 44 
 
 0 
 
 0 
 
 0 
 
 55 
 
 0 
 
 34 
 
 0 
 
 0 
 
 11 
 
 4 
 
 0 
 
 0 
 
 22 
 
 8 
 
 0 
 
 0 
 
 34 
 
 0 
 
 0 
 
 0 
 
 45 
 
 4 
 
 0 
 
 0 
 
 56 
 
 8 
 
 S5 
 
 0 
 
 0 
 
 11 
 
 8 
 
 0 
 
 0 
 
 23 
 
 4 
 
 0 
 
 0 
 
 35 
 
 0 
 
 0 
 
 0 
 
 46 
 
 8 
 
 0 
 
 0 
 
 58 
 
 4 
 
 36 
 
 0 
 
 0 
 
 12 
 
 0 
 
 0 
 
 0 
 
 24 
 
 0 
 
 0 
 
 0 
 
 36 
 
 0 
 
 0 
 
 0 
 
 48 
 
 0 
 
 0 
 
 0 
 
 60 
 
 0 
 
 37 
 
 0 
 
 0 
 
 12 
 
 4 
 
 0 
 
 0 
 
 24 
 
 8 
 
 0 
 
 0 
 
 37 
 
 0 
 
 0 
 
 0 
 
 49 
 
 4 
 
 0 
 
 0 
 
 61 
 
 8 
 
 88 
 
 0 
 
 <> 
 
 12 
 
 8 
 
 0 
 
 0 
 
 25 
 
 4 
 
 0 
 
 0 
 
 38 
 
 0 
 
 0 
 
 0 
 
 50 
 
 8 
 
 0 
 
 0 
 
 63 
 
 4 
 
 89 
 
 0 
 
 0 
 
 13 
 
 0 
 
 0 
 
 0 
 
 26 
 
 0 
 
 0 
 
 0 
 
 S9 
 
 0 
 
 0 
 
 0 
 
 52 
 
 0 
 
 0 
 
 0 
 
 65 
 
 0 
 
 40 
 
 0 
 
 0 
 
 13 
 
 4 
 
 0 
 
 0 
 
 26 
 
 8 
 
 0 
 
 0 
 
 40 
 
 0 
 
 0 
 
 0 
 
 53 
 
 4 
 
 0 
 
 0 
 
 66 
 
 8 
 
 41 
 
 0 
 
 0 
 
 13 
 
 8 
 
 0 
 
 0 
 
 27 
 
 4 
 
 0 
 
 0 
 
 41 
 
 0 
 
 0 
 
 0 
 
 54 
 
 8 
 
 0 
 
 1 
 
 0 
 
 4 
 
 42 
 
 0 
 
 0 
 
 14 
 
 0 
 
 0 
 
 0 
 
 28 
 
 0 
 
 0 
 
 0 
 
 42 
 
 0 
 
 0 
 
 0 
 
 56 
 
 0 
 
 0 
 
 1 
 
 2 
 
 0 
 
 43 
 
 0 
 
 0 
 
 14 
 
 4 
 
 0 
 
 0 
 
 28 
 
 8 
 
 0 
 
 0 
 
 43 
 
 0 
 
 0 
 
 0 
 
 57 
 
 4 
 
 0 
 
 1 
 
 3 
 
 8 
 
 44 
 
 0 
 
 0 
 
 14 
 
 8 
 
 0 
 
 0 
 
 29 
 
 4 
 
 0 
 
 0 
 
 44 
 
 0 
 
 0 
 
 0 
 
 58 
 
 8 
 
 0 
 
 1 
 
 5 
 
 4 
 
 45 
 
 0 
 
 0 
 
 15 
 
 0 
 
 0 
 
 0 
 
 30 
 
 0 
 
 0 
 
 0 
 
 45 
 
 0 
 
 0 
 
 0 
 
 60 
 
 0 
 
 0 
 
 1 
 
 7 
 
 0 
 
 46 
 
 0 
 
 0 
 
 15 
 
 4 
 
 0 
 
 0 
 
 30 
 
 8 
 
 0 
 
 0 
 
 46 
 
 0 
 
 0 
 
 0 
 
 61 
 
 4 
 
 0 
 
 1 
 
 8 
 
 8 
 
 47 
 
 0 
 
 0 
 
 15 
 
 8 
 
 0 
 
 0 
 
 31 
 
 4 
 
 0 
 
 0 
 
 47 
 
 0 
 
 0 
 
 0 
 
 62 
 
 8 
 
 0 
 
 I 
 
 10 
 
 4 
 
 48 
 
 0 
 
 0 
 
 16 
 
 0 
 
 0 
 
 0 
 
 32 
 
 0 
 
 0 
 
 0 
 
 48 
 
 0 
 
 0 
 
 0 
 
 64 
 
 0 
 
 0 
 
 1 
 
 12 
 
 0 
 
 49 
 
 0 
 
 0 
 
 16 
 
 4 
 
 0 
 
 0 
 
 32 
 
 8 
 
 0 
 
 0 
 
 49 
 
 0 
 
 0 
 
 0 
 
 65 
 
 4 
 
 0 
 
 1 
 
 13 
 
 8 
 
 50 
 
 0 
 
 0 
 
 16 
 
 8 
 
 0 
 
 0 
 
 33 
 
 4 
 
 0 
 
 0 
 
 50 
 
 0 
 
 0 
 
 0 
 
 66 
 
 8 
 
 0 
 
 1 
 
 15 
 
 4 
 
 60 
 
 0 
 
 0 
 
 20 
 
 0 
 
 0 
 
 0 
 
 40 
 
 0 
 
 0 
 
 0 
 
 60 
 
 0 
 
 0 
 
 1 
 
 12 
 
 0 
 
 0 
 
 1 
 
 32 
 
 0 
 
 70 
 
 0 
 
 0 
 
 23 
 
 4 
 
 0 
 
 0 
 
 46 
 
 8 
 
 0 
 
 1 
 
 2 
 
 0 
 
 0 
 
 1 
 
 25 
 
 4 
 
 0 
 
 1 
 
 48 
 
 8 
 
 80 
 
 0 
 
 0 
 
 26 
 
 8 
 
 0 
 
 0 
 
 53 
 
 4 
 
 0 
 
 1 
 
 12 
 
 0 
 
 0 
 
 1 
 
 38 
 
 8 
 
 0 
 
 1 
 
 65 
 
 4 
 
 90 
 
 0 
 
 0 
 
 30 
 
 0 
 
 0 
 
 0 
 
 60 
 
 0 
 
 0 
 
 1 
 
 22 
 
 0 
 
 0 
 
 1 
 
 52 
 
 0 
 
 0 
 
 2 
 
 14 
 
 0 
 
 IdO 
 
 0 
 
 0 
 
 33 
 
 4 
 
 0 
 
 0 
 
 66 
 
 8 
 
 0 
 
 1 
 
 32 
 
 0 
 
 0 
 
 1 
 
 65 
 
 4 
 
 0 
 
 2 
 
 30 
 
 8 
 
 200 
 
 0 
 
 0 
 
 66 
 
 8 
 
 0 
 
 1 
 
 65 
 
 4 
 
 0 
 
 2 
 
 64 
 
 0 
 
 0 
 
 3 
 
 62 
 
 8 
 
 1 
 
 0 
 
 61 
 
 4 
 
 300 
 
 0 
 
 1 
 
 32 
 
 0 
 
 0 
 
 2 
 
 64 
 
 0 
 
 1 
 
 0 
 
 28 
 
 0 
 
 1 
 
 1 
 
 60 
 
 0 
 
 1 
 
 S 
 
 24 
 
 0 
 
 400 
 
 0 
 
 1 
 
 65 
 
 4 
 
 0 
 
 3 
 
 62 
 
 8 
 
 1 
 
 1 
 
 60 
 
 0 
 
 1 
 
 3 
 
 57 
 
 4 
 
 2 
 
 I 
 
 54 
 
 8 
 
 500 
 
 0 
 
 2 
 
 30 
 
 8 
 
 I 
 
 0 
 
 61 
 
 4 
 
 1 
 
 3 
 
 24 
 
 0 
 
 2 
 
 1 
 
 54 
 
 8 
 
 3 
 
 0 
 
 17 
 
 4 
 
 600 
 
 0 
 
 2 
 
 64 
 
 0 
 
 1 
 
 1 
 
 60 
 
 0 
 
 2 
 
 0 
 
 56 
 
 0 
 
 2 
 
 3 
 
 52 
 
 0 
 
 3 
 
 2 
 
 48 
 
 0 
 
 700 
 
 0 
 
 3 
 
 29 
 
 4 
 
 1 
 
 2 
 
 58 
 
 8 
 
 2 
 
 2 
 
 20 
 
 0 
 
 3 
 
 1 
 
 49 
 
 4 
 
 4 
 
 1 
 
 10 
 
 8 
 
 800 
 
 0 
 
 3 
 
 62 
 
 8 
 
 1 
 
 3 
 
 57 
 
 4 
 
 2 
 
 3 
 
 52 
 
 0 
 
 3 
 
 3 
 
 46 
 
 8 
 
 4 
 
 3 
 
 41 
 
 4 
 
 900 
 
 1 
 
 0 
 
 28 
 
 0 
 
 2 
 
 0 
 
 56 
 
 0 
 
 3 
 
 1 
 
 16 
 
 0 
 
 4 
 
 1 
 
 44 
 
 0 
 
 5 
 
 2 
 
 4 
 
 0 
 
 1000 
 
 1 
 
 0 
 
 61 
 
 4 
 
 2 
 
 1 
 
 54 
 
 8 
 
 3 
 
 2 
 
 48 
 
 0 
 
 4 
 
 3 
 
 41 
 
 4 
 
 6 
 
 0 
 
 34 
 
 8 
 
 2000 
 
 2 
 
 1 
 
 54 
 
 8 
 
 4 
 
 3 
 
 41 
 
 4 
 
 7 
 
 1 
 
 28 
 
 0 
 
 9 
 
 3 
 
 14 
 
 8 
 
 12 
 
 1 
 
 1 
 
 4 
 
 3000 
 
 3 
 
 2 
 
 48 
 
 0 
 
 7 
 
 1 
 
 28 
 
 0 
 
 11 
 
 0 
 
 8 
 
 0 
 
 14 
 
 2 
 
 56 
 
 0 
 
 18 
 
 1 
 
 36 
 
 0 
 
 4000 
 
 4 
 
 3 
 
 41 
 
 4 
 
 9 
 
 3 
 
 14 
 
 8 
 
 14 
 
 2 
 
 56 
 
 0 
 
 19 
 
 2 
 
 29 
 
 4 
 
 24 
 
 2 
 
 2 
 
 8 
 
 5000 
 
 6 
 
 0 
 
 34 
 
 8 
 
 12 
 
 1 
 
 1 
 
 4 
 
 18 
 
 I 
 
 36 
 
 0 
 
 24 
 
 2 
 
 2 
 
 8 
 
 30 
 
 2 
 
 37 
 
 4 
 
 6000 
 
 7 
 
 1 
 
 28 
 
 0 
 
 14 
 
 2 
 
 56 
 
 0 
 
 22 
 
 0 
 
 16 
 
 0 
 
 29 
 
 1 
 
 44 
 
 0 
 
 36 
 
 3 
 
 4 
 
 0 
 
 7000 
 
 8 
 
 2 
 
 21 
 
 4 
 
 17 
 
 0 
 
 42 
 
 8 
 
 25 
 
 2 
 
 64 
 
 0 
 
 34 
 
 1 
 
 17 
 
 4 
 
 12 
 
 3 
 
 38 
 
 8 
 
 8000 1 
 
 9 
 
 3 
 
 14 
 
 8 
 
 19 
 
 2 
 
 29 
 
 4 
 
 29 
 
 1 
 
 44 
 
 0 
 
 39 
 
 0 
 
 58 
 
 8 
 
 19 
 
 0 
 
 5 
 
 4 
 
 9000 ill 
 
 0 
 
 8 
 
 0 
 
 22 
 
 0 
 
 16 
 
 0 
 
 33 
 
 0 
 
 24 
 
 0 
 
 44 
 
 0 
 
 32 
 
 0 
 
 55 
 
 0 
 
 40 
 
 0 
 
 10000 |12 
 
 1 
 
 1 
 
 4 
 
 24 
 
 2 
 
 2 
 
 8 
 
 36 
 
 3 
 
 4 
 
 0 
 
 49 
 
 0 
 
 5 
 
 4 |61 
 
 1 
 
 6 
 
 8 
 
 The left-hand column contains the area of the wall in superficial feet ; 
 the adjacent columns the quantity, reduced to the standard thickness, ac- 
 cording- to the difierent thicknesses on the top. 
 
 Example. What is the quantity of reduced brick-work in a wall contain- 
 ing- '^540 superficial feet, 2 bricks thick ? 
 
 Divide the number as in the preceding- table, into its component parl^^ 
 Bay 4540= 4000 -j- 600 40, then by the table. 
 
 R. Q. F. In. 
 
 4000 contains 19 2 29 4 
 
 500 ... 2 1 54 8 
 
 40 ... 0 0 53 4 
 
 82 1 14 
 
AND MACHINIST. 
 
 559 
 
 Tlie game by rule. 
 
 4540 
 
 4 number of half bricks. 
 
 3)18150( R. Q. F. In. as above. 
 
 272) 60,53 + 4(2? 1 1 4 
 
 ,544 
 
 613 
 
 541 
 
 ^ of a rod 68) 69 (1 
 68 
 
 1 
 
 TABLE III. 
 
 Shews the^ value of reduced brick- work per rod, calculated at the se- 
 veral prices of £3 5s. £3 10.9. £3 15s. £4 Os. £4 5s. and £4 10s. per rod 
 for mortar, labour, and scaffolding ; and of bricks from £1 10s. to £3 
 Os. per thousand ; allowing 4500 bricks to the rod. 
 
 Bricks per 
 thousand. 
 
 Mortar and 
 Labour 
 3/. 5s, 
 per rod. 
 
 Mortar and 
 Labour 
 3^. IOj. 
 per rod. 
 
 Mortar and 
 Labour 
 31. 15s. 
 per rod. 
 
 Mortar and 
 Labour 
 4/. 05. 
 per rod. 
 
 Mortar and 
 Labour 
 41. 5s. 
 per rod. 
 
 Mortar and 
 Labour 
 4/. 105. 
 per rod. 
 
 £. 
 
 s. 
 
 d. 
 
 £. 
 
 s. 
 
 d. 
 
 £. 
 
 s. 
 
 d. 
 
 £. 
 
 s. 
 
 d. 
 
 £. 
 
 s. 
 
 d. 
 
 £. 
 
 s. 
 
 d. 
 
 £. 
 
 .5. 
 
 d. 
 
 1 
 
 10 
 
 0 
 
 10 
 
 0 
 
 0 
 
 10 
 
 5 
 
 0 
 
 10 
 
 10 
 
 0 
 
 10 
 
 15 
 
 0 
 
 11 
 
 0 
 
 0 
 
 11 
 
 5 
 
 0 
 
 I 
 
 .12 
 
 0 
 
 10 
 
 9 
 
 0 
 
 10 
 
 14 
 
 0 
 
 10 
 
 19 
 
 0 
 
 11 
 
 4 
 
 0 
 
 11 
 
 9 
 
 0 
 
 11 
 
 14 
 
 0 
 
 1 
 
 14 
 
 0 
 
 10 
 
 18 
 
 0 
 
 11 
 
 3 
 
 0 
 
 11 
 
 8 
 
 0 
 
 11 
 
 13 
 
 0 
 
 11 
 
 18 
 
 0 
 
 12 
 
 3 
 
 0 
 
 1 
 
 16 
 
 0 
 
 11 
 
 7 
 
 0 
 
 11 
 
 12 
 
 0 
 
 11 
 
 17 
 
 0 
 
 12 
 
 2 
 
 0 
 
 12 
 
 7 
 
 0 
 
 12 
 
 12 
 
 0 
 
 1 
 
 18 
 
 0 
 
 11 
 
 16 
 
 0 
 
 12 
 
 1 
 
 0 
 
 12 
 
 6 
 
 0 
 
 12 
 
 11 
 
 0 
 
 12 
 
 16 
 
 0 
 
 13 
 
 1 
 
 0 
 
 2 
 
 0 
 
 0 
 
 12 
 
 5 
 
 0 
 
 12 
 
 10 
 
 0 
 
 12 
 
 15 
 
 0 
 
 13 
 
 0 
 
 0 
 
 13 
 
 5 
 
 0 
 
 13 
 
 10 
 
 0 
 
 2 
 
 2 
 
 0 
 
 12 
 
 14. 
 
 0 
 
 12 
 
 19 
 
 0 
 
 13 
 
 4 
 
 0 
 
 13 
 
 9 
 
 0 
 
 13 
 
 14 
 
 0 
 
 13 
 
 19 
 
 0 
 
 2 
 
 4 
 
 0 
 
 13 
 
 3 
 
 0 
 
 13 
 
 8 
 
 0 
 
 13 
 
 13 
 
 0 
 
 13 
 
 18 
 
 0 
 
 14 
 
 3 
 
 0 
 
 14 
 
 8 
 
 0 
 
 2 
 
 6 
 
 0 
 
 13 
 
 12 
 
 0 
 
 IS 
 
 17 
 
 0 
 
 14 
 
 2 
 
 0 
 
 14 
 
 7 
 
 0 
 
 14 
 
 12 
 
 0 
 
 14 
 
 17 
 
 0 
 
 2 
 
 8 
 
 0 
 
 14 
 
 1 
 
 0 
 
 14 
 
 6 
 
 0 
 
 14 
 
 11 
 
 0 
 
 14 
 
 16 
 
 0 
 
 15 
 
 1 
 
 0 
 
 15 
 
 6 
 
 0 
 
 2 
 
 10 
 
 0 
 
 14 
 
 10 
 
 0 
 
 14 
 
 15 
 
 0 
 
 15 
 
 0 
 
 0 
 
 15 
 
 5 
 
 0 
 
 15 
 
 10 
 
 0 
 
 15 
 
 15 
 
 0 
 
 2 
 
 12 
 
 0 
 
 14 
 
 19 
 
 0 
 
 15 
 
 4 
 
 0 
 
 15 
 
 9 
 
 0 
 
 15 
 
 14 
 
 0 
 
 15 
 
 19 
 
 0 
 
 16 
 
 4 
 
 0 
 
 2 
 
 14 
 
 0 
 
 15 
 
 8 
 
 0 
 
 15 
 
 13 
 
 0 
 
 15 
 
 18 
 
 0 
 
 16 
 
 3 
 
 0 
 
 16 
 
 8 
 
 0 
 
 16 
 
 13 
 
 0 
 
 2 
 
 16 
 
 0 
 
 15 
 
 17 
 
 0 
 
 16 
 
 2 
 
 0 
 
 16 
 
 7 
 
 0 
 
 16 
 
 12 
 
 0|16 
 
 17 
 
 0 
 
 17 
 
 2 
 
 0 
 
 2 
 
 18 
 
 0 
 
 16 
 
 6 
 
 0 
 
 16 
 
 11 
 
 0 
 
 16 
 
 16 
 
 0 
 
 17 
 
 1 
 
 0 17 
 
 6 
 
 0 
 
 17 
 
 11 
 
 0 
 
 3 
 
 0 
 
 0 
 
 16 
 
 15 
 
 0 
 
 17 
 
 0 
 
 o;i7 
 
 5 
 
 0 
 
 17 
 
 10 
 
 0,17 
 
 15 
 
 0 
 
 18 
 
 0 
 
 0 
 
 Exatnple. What is the price of a rod of brick-work, when the rate of bricks 
 is £2 2s. per thousand, and the price of mortar £4 5s. per rod ? 
 
 Look from the given column of bricks until you come under £4 5s. the 
 given price of labour and mortar, and you will find £13 14s. the price of 
 the rod. 
 
560 
 
 THE OPERATIVE MECHANIC 
 
 CARPENTRY. 
 
 This branch of building comprises the art of employing 
 timber in the construction of edifices. 
 
 The art of employing timber in building may be classed 
 under two distinct branches^ Carpentry and Joinery. 
 
 Carpentry comprehends the large and rough description 
 of work^ or that which is requisite in the construction and 
 stability of an edifice ; and Joinery^ the fittings up and de- 
 corative work, so necessary to the completion of a building. 
 
 Carpentry is, in general, valued by the cubical foot ; and 
 joinery by the superficial foot. 
 
 The principal operations which timbers have to undergo, 
 from the time of their arrival in the carpenter's yard to 
 their final destination in an edifice, may be classed under 
 two general heads ; those which respect individual prices, 
 and those which respect their dependence on others. 
 
 Under the former of these heads is the pit-saw, by means 
 of which, whole pieces of timber are divided, and reduced 
 into their respective sized scantlings. 
 
 The term scantling implies dimensions in breadth and 
 thickness, without any regard to length. 
 
 Planing, is the operation by which wood is reduced to a 
 smooth and uniform surface, by means of an instrument 
 called a plane, which takes a thin shaving off the surface of 
 the wood, as it is moved backwards and forwards in a 
 straight line by the hands of the workmen. There are, 
 however, other operations of the plane besides that of re- 
 ducing timber to an uniform and smooth surface, termed 
 g7'ooving, rehating, and moulding, 
 
 Groovmg is forming a channel on the surface of a piece 
 of wood, by taking away so much of the solid as is of 
 the shape and size of the groove required. 
 
 Rabathig or rebating, is reducing a piece by taking away 
 from the angles a prism of the shape and size of the rabate 
 required, so as to form an internal angle, and generally a 
 right angle. This operation is frequently required in con- 
 structing door cases, and the frames of casement windows : 
 the rabate, or groove, being intended as a ledge for the door 
 or casement to rest in. 
 
 The pieces being cut into their proper scantlings, the next 
 operation is the joining them together. 
 
561 
 
 'and machinist. 
 
 In this department we shall treat first, of the most approved 
 methods of lengthening beams, by w^hat is termed scarfing, 
 or joining them in pieces ; secondly, of the strengthening 
 of beams by trussing ; thirdly, of the methods of joining 
 two timbers at angles, in any given direction ; and lastly, of 
 the mode of connecting several timbers in order to com- 
 plete the design, and to effect certain powers respectively 
 required by each individual piece. 
 
 To lengthen a piece of timber implies the act of joining 
 or fastening tw^o clistinct pieces, so that a part of the*^ end of 
 one shall lap upon the end of another, and the surfaces 
 of both, being one continued plane, form a close joint, 
 called by w^orkmen a scarf. It is manifest, that two bodies, 
 joined together and intended to act as one continued piece, 
 in a state of tension, or compression, cannot, by any possi- 
 ble means, be so strong as either pieces taken separately. 
 It, therefore, requires much attention, and careful discri- 
 mination, in the choice and selection of such methods as 
 are the most applicable to the peculiar circumstances o* 
 the case. Every two pieces of timber joined in the manner 
 thus described, and, indeed, in most other cases, require 
 some force to compress them equally on each side, and 
 more particularly udien the pieces are light ; for this pur- 
 pose iron bolts are used, wdiich act as a tie, and possess the 
 same effect as two equal and opposite forces would have in 
 compressing the beam on each side the joint : and as the co- 
 hesive power of iron is very great, the hole, which is made 
 to receive the bolt, may be of such dimensions as will not, 
 in the least degree, tend to diminish the strength of the 
 timber. When wooden pins are used, the bore is larger, and 
 the joints weaker ; consequently the two pieces, thus con- 
 nected, are not held together by any compression of the pin, 
 but merely by the friction of the individual pieces. 
 
 No specific distance can be laid down for the length of the 
 scarf, though, in general, it may be observed, that, a long 
 scarf has but little effect in diminishing the cohesive strength 
 of a compound piece of timber ; on the contrary, it affords 
 an opportunity of increasing the number of bolts. 
 
 Fig. 558 shows the method of joining two pieces of timber by means 
 of a single step on each piece. 
 
 By this method more than one-half the power is lost ; and 
 this scarf is not calculated to resist the force of tension 
 equal to a single piece sawed half through its thickness from 
 the opposite side, at a distance equal to the leqgth of the 
 
 2 o 
 
562 
 
 THE OPERATIVE MECHANIC 
 
 scarf ; by the application of straps, however, it may be made 
 to resist a much greater force. 
 
 Fig". 559 represents a scarf with parallel joints, and a sing-le table upon 
 each piece. 
 
 In this the cohesive strength is decreased in a greater 
 degree than the preceding example, by the projection of the 
 table ; but this affords an opportunity of driving a wedge 
 through the joint between the ends of the tables, and there- 
 by forcing the abutting parts to a joint. 
 
 A scarf of this description to be longer than those which 
 have no tables, and the transverse parts of the scarf, must 
 be strapped and bolted. 
 
 Fig. 5GO presents us with the same opportunity of wedging as before. 
 
 In this figure, if the parts LM and NO be compressed together by bolts 
 as firmly as if they were but one piece, and if the projection of the tables 
 be equal to the transverse parts of the joints L and O, the loss of strength, 
 compared with that of a solid piece, will be no more than what it w'ould 
 be at L and O. 
 
 Strapping across the transverse part of the joint is much 
 the best and most effectual way of preventing the pieces 
 from being drawn from each other, by the sliding of the 
 longitudinal parts of the scarf, and, therefore, giving to the 
 bolts an oblique position. 
 
 Fig. 561 is a scarf formed by several steps. 
 
 In this, if all the transverse parts of the steps be equal, 
 and the longitudinal parts strongly compressed by bolts, the 
 loss of strength will only be a fourth, compared to that of a 
 solid piece, there being four transverse parts, that is, the 
 part which the end of the steps is of the whole. 
 
 Fig. 562 is a scarf w ith a bevel joint, and equally as eligible for or- 
 dinary purposes as any in use. 
 
 Figs. 561 and 563. Scarfs intended for longer bearings than the pre- 
 ceding one. 
 
 Fig. 564 represents the method of constructing a compound timber, 
 when tw'o pieces are not of adequate length to allow them to lap, by 
 means of a third piece joined to both by a double scarf, formed by several 
 gradations or steps, the pieces abutting upon each other with the middle of 
 the connecting piece over their abutment. 
 
 lliat which shall next claim our attention is a consider- 
 ation of the principles and the best methods of strengthen- 
 ing beams by trussing. 
 
 When girders are extended beyond a certain length, they 
 bend under their own weight, and the degree of curvature 
 increases in a proportion far greater than that of their 
 lengths. The besl method to obviate this saggmg^ as it is 
 
Trum 558 to 566 
 
 FL8o 
 
 
 556 
 
 
 559 
 
 
 
 r' 
 
 
 560 
 
 1 
 
 1 
 
 ^P=5 ^ 
 
 562 
 
 562 
 
 
 
 563 
 
 
 
 564 
 
 
 9 a a a a a a /^| 
 
 1 
 
 [^ 
 
V 
 
 
 
AND MACHINIST. 
 
 563 
 
 termed, without the support of posts, &c. is to make the 
 beam in two equal lengths, and insert a truss, so that when 
 the two pieces are confined together by bolts, the truss may 
 be included between them, and cause them to act as a tie. 
 To prevent any unfavourable results from natural tendency 
 of the timbers to shrink, the posts of the truss may be made 
 of iron, and screwed, and nutted at the ends ; and to give 
 a still stronger abutment, the braces may be let in with 
 grooves into the side of each flitch, or piece, which form 
 the beam. The ends of the abutments are also made of 
 iron, screwed, or nutted, at each of the ends, and bolted 
 through the thickness of both pieces, with a broad part in 
 the middle, that the braces may abut upon the whole di- 
 mension of their section ; or, otherwise, the abutments are 
 made in the form of an inverted wedge at the bottom, and 
 rise cylindrically to the top, where they are screwed and 
 nutted. 
 
 These methods may be constructed either with one king- 
 bolt in the middle, or with a truss-bolt at one-third of the 
 ■ length from each end. When two bolts are applied, they 
 include a straining place in the middle. The two braces 
 may be constructed of oak, or cast or wrought iron ; but 
 the latter material is seldom used : for, as all metals are 
 liable to contract, wood is considered the best material. 
 With respect to the bolts, iron is indispensable. * 
 
 The higher the girder is, the less are the parts liable to 
 be effected by the stress ; and, consequently, the risk of 
 their giving way under heavy weights, or through long bear- 
 ings, is less. 
 
 Figs. 565 and 566 are two examples of girders calculated from their 
 rise to sustain very heavy weights. If the tie beam be very strong, the 
 abutments may be wedged ; but the wedges ought to be very long, and 
 a little taper, that there may be no inclination to rise. The excess of 
 length may afterwards be taken off. 
 
 In joining two timbers together, in any given direction, 
 the joinings, as practised by carpenters, are almost infinitely 
 various ; and though some are executed with a view merely 
 to gratify the eye, the majority have decided advantages, 
 and each, in peculiar cases, is to be preferred. In this 
 treatise, our limits will not permit us to enter upon a de- 
 scription of such as yield no substantial benefit, or are em- 
 ployed only in connecting small work ; but, even in these, 
 the skill of the workman may at all times be discovered by his 
 selection of materials. It may here be observed, that, as 
 all timber is either more or less, according to the dryness^ 
 
 2o2 
 
THE OPERATIVE MECHANIC 
 
 564 
 
 and the quality of the timber used, subject to shrink, the 
 carpenter should very carefully consider how much the di- 
 mensions of his framings will be affected by it, and so 
 arrange the inferior pieces that their shrinkage shall be 
 in the same direction as the shrinkage of the framing, and 
 80 conduce to the greater stability of the whole. If this be 
 not attended to, the parts will separate and split asunder. 
 
 Two pieces of timber may be connected either by making 
 both planes of contact parallel with or at right angles to 
 the fibres, or by making the joint parallel with the fibres of 
 the one piece, and at right or oblique angles to the other, or 
 at oblique angles to the fibres of both pieces. 
 
 If two pieces of timber are connected, so that the joint 
 runs parallel with the fibres of both, it is called a longitudi- 
 nal joint ; but when the place of the joint is at right angles 
 to the fibres of both, an abutting joint. Butting and mitre 
 joints are seldom used in carpentry. 
 
 When two pieces of timber are joined together at one or 
 more angles, the one piece will meet the other and form 
 one angle, or by crossing it make two angles, or the two 
 pieces will cross "each other and form four angles. 
 
 In all the following cases of connecting two timbers-, 
 it is supposed, that the sides of the pieces are parallel with 
 the fibres, or, when the fibres are crooked, as nearly so as 
 possible ; and that each piece, the four sides being at right 
 angles to each other, has at least one of its surfaces in the 
 same plane with those of the other. The angle or angles 
 so formed will be either right or obtuse. 
 
 Fig. 537, is an example of a notched joint, which is the most common 
 and simple form, and, in some cases, the strongest for joining two timbers 
 at one or more angles, particularly when bolted at the joint. The form 
 of the joint may be varied, according to the position of the sides of the 
 pieces, the number of angles, the quantity and direction of the stress on 
 the one or both pieces, or by any combination of their circumstances. 
 Notching admits two pieces to be joined at from one to four angles ; but 
 joining by mortise and tenon admits only from one to two angles. 
 
 In joining by mortise and tenon, four sides of the mortise 
 should, if possible, be at right angles to each other, and to 
 the surface whence it is recessed, and two of these sides 
 parallel with each of the sides which forms a right angle with 
 tiie side from which the mortise is made : the fifth plane, that 
 is, the bottom of the mortise, is parallel with the top or sur- 
 face iVom which the mortise is made. Four sides of the tenon 
 “ho'iid b? parallel to the four sides of the piece ; but there 
 aicMuary cases where a digression is unavoidable* 
 
AND MACHINIST. 
 
 
 In the application of timbers to buildings, we will here 
 suppose, that all pieces cut for use have a rectangular sec- 
 tion, and when laid down, have their sides perpendicular 
 to, and parallel with, the horizon. If two pieces of timber, 
 therefore, are to be joined at four angles, cut a notch in one 
 piece equal to the breadth of the other, so as to leave the 
 remaining part of the thickness sufficiently strong, and in- 
 sert the other piece in the notch ; or, if the work is required 
 to be very firm, notch each piece reciprocally to each other’s 
 breadth, and fasten them together by pins, spikes, or bolts, 
 as the case may require. This form is applicable when the 
 pieces are equally exposed to a strain. 
 
 Fig-. 568 will fully elucidate this description of joint. 
 
 The framing of timber by dove-tail notching is principal- 
 ly applicable to horizontal framing, where the lower timber 
 is sufficiently supported. Where the lower timber is unsup- 
 ported it is common to use mortise and tenon, w hich does 
 not materially weaken the timber ; but when the timber is 
 notched from the upper side, the operation reduces its thick- 
 ness, and consequenlly impairs its strength, though, if the 
 solid of one piece fill the excavation of the other, and both 
 be lightly driven or forced together, according to Du Hamel, 
 it will, if not cut more than one third through, rather increase 
 than decrease in strength. It may, however, be observed, 
 that in large works, where heavy timbers are employed, it 
 is difficult, and almost impossible, to fit the mortise and 
 tenon with due accuracy ; and even if the joints were closely 
 fitted at first, the shrinking would occasion cavities on the 
 sides, that w^ould render the tenons of no avail, because the 
 axis of fracture would be nearer to the breaking or under- 
 side of the supporting piece. What has been here said 
 with respect to timbers placed horizontally, applies to fram- 
 ing in every position, when the force is to fall on the plane 
 of the sides ; and if a number of pieces thus liable to lateral 
 pressure on either side, are to be framed into two other stiff 
 pieces, the mortise and tenon will prove best for the purpose. 
 
 If it be required to connect two pieces of timber so as to 
 form two right angles, and t» be immovable, when the 
 transverse is held or fixed fast, and the standing piece pulled 
 in a direction of its length, cut a dove-tail notch across the 
 breadth of the transverse piece, and notch out the vertical 
 sides of the standing piece at the end, so as to form a si- 
 milar and equal solid. In some kinds of work, besides the 
 dove-tail, an additional notch is cut to receive the shoulder 
 
606 ' n'HE OPERATIVE MECHANIC 
 
 of the lower piece. If the position of these pieces be hori- 
 zontal, and the upper is of sufficient weight, or is press- 
 ed down by any considerable force, when the pieces are 
 placed together, the dove- tail will be sufficiently strong 
 without the assistance of pins, spikes, or bolts. This con- 
 struction requires the timbers to be well seasoned 5 for 
 otherwise the shrinking will permit the standing piece to be 
 drawn out of the transverse, and thus defeat the purpose of 
 the construction. 
 
 In introducing binding joists, which will, as they have to 
 support the bridging joists and boarding of the floor, be 
 framed into girders, there will be a considerable strain at 
 the extremities, so that it is necessary, in order to make 
 the tenons sufficiently strong, to have a shorter bearing te- 
 non attached to the principal tenon, with a sloping shoulder 
 above, called a tusk^ which term is likewise applied to this 
 tenon, called the tusk tenon. 
 
 When two parallel pieces, which are quite immovable, 
 are to have another piece framed between them, the prin- 
 ciple is, to insert the one end of the tenon of the piece to be 
 framed in a shallow mortise, and make a long mortise in the 
 opposite side of the other timber ; so that when the cross 
 piece is moved round the shoulder of the other extremity as 
 a centre, it may slide home to its situation. This mode of 
 framing a transverse piece between two others, is employed 
 in trimming in ceiling joists, which joists are seldom or 
 never cut and fitted into the binding joists before the build- 
 ing is covered over. The binding joists are always mortised 
 before they are disposed in the situation to receive the ceil- 
 ; ing joists. 
 
 ' When a transverse piece of timber is to be framed be- 
 tween two parallel joists, whose vertical surfaces are not pa- 
 i rallel, turn the upper edge of the transverse piece downwards 
 ; upon the upper horizontal surface of the joists, mark the in- 
 terval, or distance between them, upon the surface of the 
 transverse piece now under ; then placing the edge over the 
 place where it is intended to let down, turn the transverse 
 piece in the way it is intended to be framed, apply a straight 
 edge to the oblique surface of the joist, and slide the trans- 
 verse piece so as to bring the mark on the upper side of it on 
 a line with the straight edge, which being done, proceed 
 in the same manner with the other end, and the two lines 
 drawn on the vertical sides of the intermediate piece will 
 give the shoulders of the tenons. This act of framing a 
 transverse joist between two others is termed tumbling in 
 
AND MACHINIST. 5G7 
 
 joists ; and is particularly useful when the timber is warped 
 or twisted. 
 
 In order that the reader may the more fully understand the 
 preceding description of the joinings of timbers, we have 
 annexed a plate (to which the subjoined description refers,) 
 of the best methods now m practice. 
 
 Fi^. 457. No. 1 and 2, and 3 and 4, exhibit two methods of a simple 
 joint, where the two pieces are halved upon each other ; in both of which 
 the end of one piece does not pass the outer surface of the other. No. S 
 and 4 represent the two pieces before put together. 
 
 Fig. 568, is a method of joiuing timber, when the end of one piece 
 passes the end of the other at a small distance. No. 1 represents the 
 pieces before joined. 
 
 Fig. 569 shews how two pieces may be joined by what is termed a 
 niche. — In this case, the two pieces should be fixed to another by a bolt at 
 right angles to the niche joint. 
 
 Fig. 570. How one piece of timber may be joined to another, when one 
 of the pieces is extended on both sides of the other piece. Nos. 1 and 2 
 show the pieces before put together. 
 
 Fig. 571 shows the manner of joining the binding joists and girders.' 
 No. 1. The binding joist preparedforbeing joined to the girder. 
 
 Fig. 572 is the general and most approved method of framing the rafter 
 foot into the girder. 
 
 Fig. 573 is a section of the beam, shewing the different shoulders of 
 the rafter foot. 
 
 Fig. 574 is another example, preferable to the former, because the 
 abutment of the inner part is better supported. In this the beam, when 
 no broader than the rafter is thick, may be weakened, in which case, it 
 would require a much deeper socket than is here given ; and perhaps an 
 advantage would be gained by introducing a joint like fig. 575. 
 
 Fig. 576 is the method of introducing iron straps to confine the foot of 
 the rafter to the tie-beam. 
 
 When it is found necessary to employ iron straps for 
 strengthening a joint, considerable attention is required to 
 place them properly. The first thing to be ascertained is 
 the direction of the strain. We must then endeavour, as 
 near as we can, to resolve this strain into a strain parallel 
 to each piece, and another perpendicular to it. Then the 
 strap which is to be made fast to any of the pieces, must be 
 so fixed that it shall resist in the direction parallel to the 
 piece. 
 
 The strap which is generally misplaced, is that which 
 connects the foot of the rafter with the tie-beam. It binds 
 down the rafter; but does not act against its horizon- 
 tal thrust. It should be placed farther back on the beam, 
 and have a bolt through it, to allow it to turn round ; and 
 should embrace the rafter almost horizontally near the foot, 
 and be notched square with the back of the rafter. The 
 example given in No. 10 combines these requisites. By 
 
568 
 
 tH¥ OPliRATIV^B MECHAlSlc 
 
 moving round the eye-bolt^ it follows the rafter, and can • 
 not pinch and cripple it, which it always does in its ordi- 
 nary form. Straps which have eye-bolts on the very angles, 
 and allow motion round them, are considered the most 
 perfect. 
 
 Fig. 577 exhibits two methods of connecting the struts of a roof, or par- 
 tition, &c. with the king-post. 
 
 If the action of a piece of timber on another does not ex^ 
 tend, but compress, the same, there is no difficulty whatever 
 in the joint, indeed joining is unnecessary : it is enough 
 that the pieces abut on each other ; and we have only to 
 take care that the mutual pressure be equally borne by all 
 the parts, and that no lateral pressure, which may cause 
 one of the pieces to slide on the butting joint, be produced. 
 At the joggle of a king-post, a very slight mortise and 
 tenon, with a rafter, or straining beam, is sufficient. It is 
 generally best to make the butting plain, bisecting the angle 
 formed by the sides, or else perpendicular to one of the 
 pieces. For instance, the joint a is preferable to 5, and, 
 indeed, to any uneven joints, which never fail to produce 
 very unequal pressures, by which some of the parts are 
 crippled, and others splintered off. 
 
 Fig. 578 is the method of securing the tie-beam and principals, when 
 the king-post is made of an iron rod. 
 
 Fig. 579 shows a method of joining the principals with the king-post by 
 means of an iron dove-tail, which is received in a mortise at the head of 
 each principal. 
 
 Trusting that the reader will be able, from the above de- 
 scription, to comprehend the best methods of joining tim- 
 bers, we shall next proceed to describe the modes of con- 
 necting several timbers, in order to complete the design, 
 and to effect certain powers respectively required by each 
 individual piece. 
 
 In framing centres for groins, the boarding which forms 
 the interior surface is supported by transverse ribs of tim- 
 ber, which are either constructed simply, or with trusses, 
 according to the magnitude of the work ; and, as a groin 
 consists generally of two vaults intersecting each other, one 
 of them is always boarded over the same as a plain vault, 
 without any respect to the other, which is afterwards ribbed 
 and boarded so as to make out the regular surface. 
 
 Timbers inserted in walls, and at returns, or angles, are 
 joined together where the magnitude of'the building or ex- 
 posure to strain may require. There are three denomi^ 
 iiations, yiz. hand timber y linteU, and wall^piates. 
 
From 51)7 1o58o 
 
 n. 
 
 y^e^^Stocid^ xcSS’lStraftd. 
 

 
 
 
 ' '■ ' V" 
 
 '"'1 
 
 t 
 
 •V -<f* 
 ' 
 
 ..i'-C. 
 
 
 
AND MACHINIST. 
 
 569 
 
 Flooring is supported by one or more rows of parallel 
 beams, called naked, or carcase Jioonng, and is denominated 
 cither single or double. During the construction of the 
 building, the flooring, if not supported by walls or parti- 
 tions, must be shored. The framing of flooring, whether 
 single or double, depends upon the magnitude of the build- 
 ing, the horizontal dimensions of the apartments, or the 
 stress with which the surface of the boarding is likely to be 
 affected. When the flooring is intended to be veiy stiff and 
 firm, it is necessary to introduce truss girders. Naked 
 flooring, for ball-rooms, should be framed very strong, and 
 the upper part contrived with a spring, to bend with the im- 
 pression of the force, while the lower part, w^hich sustains 
 the ceiling, remains immovable. 
 
 Partitions are constructed of a number of pieces of tim- 
 ber, called scantling, placed vertically, at a specified dis- 
 tance from each other, dependent on the purposes for which 
 it is intended to answ'er. If to support girders, they should 
 be trussed, and afterwards filled in with parallel pieces, 
 called studs. 
 
 The framing ought to be so contrived, as to supersede the 
 necessity of hanging up the floor, in whatever situation the 
 doors may be placed. Truss partitions are also of the 
 greatest utility in supporting floors which are above them. 
 
 The rafters which support the covering in a roof are sus- 
 tained by one, two, or several pieces of framing, called a 
 pair of principals, placed at right angles to the ridge of the 
 roof. In roofing, many ingenious contrivances are resorted 
 to, their application depending upon the pitch of the roof, 
 the number of compartments into which it may be divided, 
 and the introduction of tie-beams. In cases where apart- 
 ments are required to be within the framing of the roof, 
 and it is inconvenient to introduce tie-beams, the sides of 
 the roof may be prevented from descending, by arching them 
 with cast-iron, or trussing them with wood in the inclined 
 planes of their sides. To restrain the pressure of the raf- 
 ters, which would be discharged at the extremities of the 
 building, a strong wall-plate, well connected in all its parts, 
 must be introduced, to act as a tie, and prevent the lateral 
 pressure from forcing out the walls. 
 
 In this construction, as well as in the former, the rafters 
 would have a tendency to become hollow, so that it is 
 necessary, in order to counteract this tendency, to introduce 
 straining beams at convenient heights ; and if it be requisite 
 to occupy very little space by the wood-work, cast-iron 
 
570 THB OPERATIVE MECHANIC 
 
 arches, abutting upon each other, and screwed with their 
 planes upon the upper sides of the rafters, are best adapted 
 for the purpose. If this and the former principle were adopt- 
 ed, the combined effect would be very great. 
 
 We shall now present the reader with a few practical ob- 
 servations. 
 
 Timber, except it stand perpendicular to the horizon, is 
 much weakened by its own weight. The bending of timber 
 is nearly in proportion to the weight laid on it. No beam 
 ought to be trusted for any long time, with above one-third 
 or one-fourth part of the weight it will absolutely carry ; 
 for experiments prove, that a far less weight will break a 
 piece of timber when hung to it a considerable time, than 
 is sufficient to break it when first applied. 
 
 The strain occasioned by pulling timber in the direction 
 of its length, is called tension. It frequently occurs in roofs, 
 and is therefore worthy of consideration. 
 
 The absolute strength of a fibre, or small thread of tim- 
 ber, is the force by which every part of it is held together, 
 and is equal to the force that would be required to pull it 
 asunder. The force required to tear any number of threads 
 asunder, is proportional to that of their sum ; but the areas 
 of the sections of two pieces of timber, composed of fibres 
 of the same kind, are as the number of fibres in each ; 
 therefore, the strength of the timber is as the areas of the 
 sections. Hence all prismatic bodies- are equally strong ; 
 that is, they will not break in one part rather than in another. 
 
 Bodies which have unequal sections, will break at their 
 smallest part ; therefore if the absolute strength required to 
 tear a square inch of each kind of timber be known, we 
 shall be able to determine the strength of any other quan- 
 tity, whatever. 
 
 The wood next to the bark, commonly called white or 
 hleOy is also weaker than the rest : and the wood gradually 
 increases in strength as we recede from the centre to the 
 blea. . 
 
 The heart of a tree is never in its centre, but always near- 
 er to the north side, and on that side the annual coats of 
 wood are thinner. In conformity to this, it is a general 
 opinion among carpenters, that that timber is strongest 
 whose annual plates are thickest. The Trachece^ or «2>- 
 vessels, are weaker than the simple ligneous fibres. These 
 air-vessels make the separations between* the annual plates, 
 and are the same in diameter, and number of rows, in 
 all trees of the same species 5 consequently, when these 
 
Bi'CLirc^S 
 
 Tram oSl to o83 
 
 TI .82 
 
AND MACHINIST. 571 
 
 are thicker, they contain a greater proportion of the simple 
 ligneous fibre. 
 
 The wood is stronger in the middle of the trunk than at 
 the springing of the branches, or at the root ; and the wood 
 of the branches is weaker than that of the trunk. 
 
 The part of the tree towards the north, in the European 
 climates, is the weakest, and that of the south side the 
 strongest : and the difference is most remarkable in hedge- 
 row trees, and such as grow singly. 
 
 All description of wood is more tenacious while green ; 
 and loses very considerably by drying, after the tree is 
 felled. 
 
 We shall now conclude these remarks with the follow- 
 ing useful problem. 
 
 Fig-. 580. To cut the strongest beam possible out of a round tree whose 
 section is a given circle. Let ab c dhe the section of the tree ; draw 
 the diameter c h, divide it into three equal parts, e and f, and from one of 
 them, as /, draw' /a perpendicular to the diameter c h ; draw ah and 
 a c, — b d and d c, and ab c d\% the strongest piece that can be cut out 
 of the tree. From this it is manifest, that the strongest beam which can be 
 cutout of a round tree, does not contain the most timber, for the greatest 
 rectangle that can be inscribed in a circle is a square, and therefore the 
 square g h i k greater than the rectangle a b c dt and yet is not the 
 strongest. 
 
 Fig. 581. Plan of a floor. — 1. Girder resting upon the walls. — 2. Bridg- 
 ing-joists. — 3. Binding-joists. — 4. Trimmers, 
 
 Nos. 1 and 2, sections of the floor. . _ 
 
 Fig. 582. A trussed partition with an opening in the middle for folding 
 doors. — 1. Head. — 2. Sill. — 3. Posts. — 4<. Braces. — 5. Studs.-— 6. Door- 
 head. — This partition, as may be seen, supports itself. 
 
 Fig. 583. A simple trussed roof. 
 
 DEFINITIONS. 
 
 Wall-plates ; pieces of timber laid on the wall, in 
 order to distribute equally the pressure of the roof, and to 
 bind the walls together. They are sometimes called raising 
 plates. 
 
 Tie-beam ; a horizontal piece of timber, connected to 
 two opposite principal rafters ; it answers a two-fold pur- 
 pose, viz. that of preventing the walls from being pushed 
 outwards by the weight of the covering, and of supporting 
 the ceiling of the rooms below. When placed above the 
 bottom of the rafters, it is called a collar^heam. 
 
 Principal rafters ; two pieces of timber in the sides of 
 the truss, supporting a grated frame of timber over them, on 
 which the covering or slating rests. ‘ 
 
 Purlines ; horizontal pieces of timber notched on the 
 principal rafters. 
 
572 
 
 THE OPERATIVE MECHANIC 
 
 Common rafters ; pieces of timber of a small section, 
 placed equidistantly upon the purlines, and parallel to the 
 principal rafters : they support the boarding to which the 
 slating is fixed. 
 
 P ole- plat es ; pieces of timber resting on the ends of 
 the tie-beams, and supporting the lower ends of the com- 
 mon rafters. 
 
 Kmg-post ; an upright piece of timber in the middle of 
 a truss, framed at the upper end into the principal rafters, 
 and at the lower end into the tie-beam ; this prevents the 
 tie-beam from sinking in the middle. 
 
 Struts ; oblique straining pieces, framed below iiito the 
 king-posts, or queen-posts, and above into the principal raf- 
 ters, which are supported by them ; or sometimes they have 
 their ends framed into beams, that are too long to support 
 themselves without bending, they are often called braces. 
 
 Other pieces of timber are introduced in roofs of a greater 
 span ; which we shall here describe. 
 
 Queen-posts ; two upright pieces of timber, framed be- 
 low into the tie-beam, and above into the principal rafters ; 
 placed equidistantly from the middle of the truss, or its 
 extremities. 
 
 Puncheons ; short ti*ansvcrse pieces of timber, fixed be- 
 tween two others for supporting them equally ; so that 
 when any force operates on the one, the other resists it 
 equally ; and if one break the other will also break. These 
 are sometimes called studs. 
 
 Straining-beam ; a piece of timber placed between two 
 others, called queen-posts^ at their upper ends, in order to 
 withstand the thrust of the principal rafters. 
 
 Straining-cill ; a piece of timber placed upon the tie- 
 beam at the bottom of two queen-posts, in order to Muth- 
 stand the force of the braces, which are acted upon by the 
 weight of the covering. 
 
 Camber-beam ; horizontal pieces of timber, made on the 
 upper edge sloping from the middle towards each end in 
 an obtuse angle, for discharging the water. They are placed 
 above the straining-beam in a truncated roof, for fixing the 
 boarding on which the lead is laid ; their ends run three or 
 four inebes above the sloping plane of the common rafters, 
 in order to form a roll for fixing the lead. 
 
 Auxiliary rafters ; pieces of timber framed in the same 
 vertical plane with the principal rafters, under, and parallel 
 to them, for giving additional support. They are sometimes 
 called principal braces, and sometimes cushion rafters^, / 
 
AND MACHINIST. 
 
 573 
 
 Joggles ; the joints at the meetings of struts, with king- 
 posts, queen-posts, or principal rafters ; or at the meeting 
 of principal rafters with king and queen- posts: the best 
 form is that which is at right angles to the struts. 
 
 Cocking, or Cogging ; the particular manner of fixing the 
 tie-beams to the wall- plates. 
 
 There are a variety of roofs differing in form, according 
 to the nature of the plan, and the law of the horizontal and 
 vertical sections. 
 
 The most simple form of a roof is that which has only 
 one row of timbers arranged in an inclined plane, and 
 throws the rain entirely on one side. This description of 
 roof is termed a shed-roof, or lean-to. 
 
 If the plan of the roof be a trapezium, and the tops of 
 the walls properly levelled, the roof cannot be executed in 
 plane surfaces, so as to terminate in a level ridge; con- 
 sequently, the sides, instead of being planes, are made to 
 wind, in order to have the summit parallel to the horizon ; 
 but the best plan is, to make the sides of the roofs planes, 
 enclosing a level space or flat, in the form of a triangle or 
 trapezium, at the summit of the roof. Roofs which are flat 
 on the top, are said to be truncated : they arc chiefly em- 
 ployed with a view to diminish the height, so as not to pre- 
 dominate over that of the walls. 
 
 If all the four sides of the roof are formed by inclined 
 planes, it is said to be hipped, and is therefore called a 
 hipped-roof ; and the inclined ridges, springing from the 
 angles of the walls, are called hips. 
 
 Roofs on circular bases, with all their horizontal sections 
 circular, the centres of the circles being in a straight line, 
 from the centre of the base perpendicular to the horizon, 
 are called roofs of revolution or rev olved-r oofs. 
 
 When the plan of the roof is a regular polygon, circle, 
 or an ellipsis, the horizontal sections being all similar to the 
 base, and the vertical section a portion of any curve, which 
 is convex on the outside, the roof is called a dome. 
 
 In roofs of rectangular buildings, when a saving of ex- 
 pense is of consequence, instead of a lead flat, which 
 must be covered with lead or copper, a valley is introduced, 
 which makes the vertical section in the form of the letter M, 
 or rather an inverted W ; hence it has obtained the name 
 of M roof. 
 
 The pitch of a roof, or the angle which its inclined side 
 forms with the horizon, is varied according to the climate 
 and the nature of the covering. 
 
THE OPERATIVE MECHANIC 
 
 574 
 
 The inhabitants of cold countries make their roofs very 
 high ; and those of warm countries^ where it seldom rains 
 or snows^ very flat. But even in the same climate the pitch 
 of the roof is greatly varied. Formerly the roofs were 
 made very high, probably with the notion that the snow 
 would slide off easier; but where there are parapets, a high 
 roof is attended with very bad effects, as the snow slips 
 down and stops the gutters, and an overflow of water is 
 the consequence ; besides, in heavy rains, the water descends 
 with such velocity, that the pipes cannot convey it away 
 soon enough to prevent the gutters from being overflowed. 
 
 The height of roofs at the present time is very rarely 
 above one- third of the span, and should never be less than 
 one-sixth. The most usual pitch for slates is that when the 
 height is one-fourth of the span, or at an angle of 26;^ de- 
 grees with the horizon. Taking this as a standard, the fol- 
 lowing table will show the degree of inclination which may be 
 given for other materials : — 
 
 
 Inclination 
 
 Height of 
 
 
 Kind of covering. 
 
 to the hori- 
 
 roof in 
 
 Weight upon a 
 
 zon in de- 
 
 parts of 
 
 square of roofing. 
 
 
 grees. 
 
 Span. 
 
 
 
 1 
 
 Deg. Min. 
 
 
 
 Copper or lead .... 
 
 3 50 
 
 * 4'8 
 
 /copper 100 
 \ lead 700 
 
 Slates large 
 
 22 0 
 
 i 
 
 , 1120 
 
 Ditto ordinary 
 
 26 33 
 
 1 
 
 / from 900 
 
 Ito 500 
 
 Stone slate 
 
 Plain tiles 
 
 29 41 
 
 9 . 
 
 7 
 
 2380 
 
 ' 29 41 
 
 4 
 
 Pan-tiles 
 
 T 
 
 1780 
 
 24 0 
 
 3 . 
 
 9 
 
 Thatch of straw, reeds. 
 
 650 
 
 45 
 
 h 
 
 A roof for a span of from 20 to 30 feet may have a truss 
 of the form shown in Fig. 583. Within this limit, the pur- 
 lines do not become too wide apart, nor the points of sup- 
 port of the tie-beam. 
 
 For spans exceeding 30 feet, and not more than 45 feet, 
 the truss shown in Fig. 584 is well adapted. Each pnrline 
 IS supported, consequently, there are no cross strains on the 
 principal rafters 5 and the points of support divide the tie- 
 beams into three comparatively short bearings. The sag- 
 ging, which usually takes place from the shrinking of the 
 heads of the queen- posts, may be avoided by letting the end 
 of the principal rafter abut against the end of the straining 
 
BnXiBINO 
 
 J’hom to o8 7 
 
 n.83 
 
 
 
 
 ' 1 
 
 684 \ 
 
 1 j 
 
 
 
 
 ^.1; ; 
 
 S h 
 
 ^SOtekleji *c SS%SfTYU*ii 
 
AND MACHINIST. 575 
 
 beam A, and notching pieces and bolting them together in 
 pairs at each joint. 
 
 When the span exceeds 45 feet, and is not more than 60 feet, the truss 
 shown in Figf. 585 is sufficiently strong for the purpose, and leaves a con- 
 siderable degree of free space in the middle. For this span the tie-beam 
 will most likely require to be scarfed, and as the bearing of that portion 
 of the tie-beam between a and h is short, the scarf should be made there. 
 The middle part of the tie-beam may be made stronger by bolting the 
 straining cill c to it. 
 
 It often occurs, that the centre aisles ornaives of churches 
 are higher than the side aisles ; a similar effect, as when the 
 tie-beam continues through, may be produced by connect- 
 ing the lower beams to the upper one, by means of braces, 
 so that the whole may be as a single beam. To illustrate 
 this mode of construction, we have given a design for a roof 
 of a church, somewhat similar to St. Martin’s in the fields, 
 London. 
 
 Fig. 586, the lower ties, AA, are so connected with the principal tie- 
 beam, B, by means of the braces, a, a, that the foot of the principal raf- 
 ters, e, c, cannot spread without stretching the tie-beam, B. The iron 
 rods, b, b, perform the office of king-posts to the ties. A, A, and are much 
 better than timber, in consequence of the shrinkage, which in this situa- 
 tion would be very objectionable. 
 
 Fig. 587 is a design for a roof of a church, or other building, requiring 
 a semicircular arched ceiling. 
 
 Domes derive their names according to the plans on 
 which they are built, circular, elliptical, or polygonal : of 
 these, the circular may be spherical, spheroidal, ellipsoidal, 
 hyperboloid al, paraboloidal, &c. Those which rise higher 
 than the radius of the base, are called surmounted domes ; 
 those that are of a less height than the radius, diminished^ 
 or surhased'^, and such as have circular bases, cupolas. 
 The most usual form for a dome is the spherical, in which 
 case, the plan is a circle, and the section a segment of a 
 circle. 
 
 The top of a large dome is often finished with a lantern, 
 supported by the framing of the dome. 
 
 The interior and exterior forms of domes are seldom 
 alike, and in the space between them, a staircase to the 
 lantern is usually made. According to the space left be- 
 tween the external and internal domes, the framing must 
 be designed. Sometimes the framing may be trussed with 
 ties across the opening ; but generally the interior dome rises 
 so high that ties cannot be obtained. 
 
 Fig. 588, No. 1, shows the construction of a dome without ties. This 
 is the most simple method, and one which is particularly applicable to 
 domes of ordinary dimensions. This example consists in placing a num- 
 
THE ©PKRATIVi: MECHANIC 
 
 fi/G 
 
 her of curved ribs, so that the lower ends stand upon and are well framed 
 into the kirb at the base, and the upper ends meet at the top, or are 
 framed into the upper kirb on which the lantern is placed. 
 
 When it occurs, as it generally does, that the pieces are 
 so long, and so much curved, that they cannot be cut out of 
 timber without being cut across the grain, so much as will 
 weaken them, they should be put together in thicknesses, 
 with the joints crossed, and well bolted together. 
 
 No. 2, shows the ribs fixed, and bolted together, with horizontal rafters 
 to receive the boarding on the exterior, and the laths on the interior, 
 T’hese ribs should be placed about two feet, or two feet six inches apart 
 at the base, and be composed of three or four thicknesses of one and a half 
 inch-deal, about 11 or 12 inches wide, M-hich, when carefully bolted 
 together with the joints judiciously broken, will stand exceedingly firm 
 and well. 
 
 To construct the ribs of a spherical dome, with eight 
 axal ribs, and one purline in the middle. 
 
 (Fig. 589.) No. 1. Let ABCDE be the plan of half the dome, udiich di- 
 vide into four equal parts at BCD and E, these points of division will 
 mark the centre of the back, or convex sides of the ribs. This being done, 
 let B 6, C c, D fi, be the plans of these ribs, with the points of division 
 in the centre. F, G, H, I, K, are the seats of the upper ends of the rilis ; 
 on the upper kirb draw a? y. No. 2, parallel to AE, then from tlie dif- 
 ferent seats of the ribs on the plan draw' perpendiculars cutting ^ y. 
 DraAv the cill, x y, its intended thickness, and complete the elevation of 
 the front and back ribs. The front ribs are quadrants, forming a semi- 
 circle on the upper side of the wall-plate, which, of course, is the diame- 
 ter. The curves of the sides of each of the other ribs are the quadrants 
 of an ellipsis of the same height with the front rib. Place the purlines 
 ill their intended situation, and having drawn the elevation and plan, as 
 shown by the dotted line, the construction is complete. 
 
 The ribs of an elliptical dome are found precisely on the 
 same principle. 
 
 Given the plan of a polygonal dome, and one of the axal 
 ribs, at right angles to one of the sides, to find the curve of 
 the angle rib and the covering. 
 
 Fig. 590. Let A, B, C, D, E, F, G, H, be the plan of an octangular 
 polygonal dome, and cab the given rib ; produce c « to d, divide the 
 curve line a BA h into any number of equal parts, the more the better, in 
 this case four, 1, 2, 3, h, which extend on the line a d ; the first from a 
 to 1, the second from 1 to 2, &c. : from the points of division, 1, 2, 3, 5, 
 draw lines parallel to B e, cutting C c, and from these points draw lines, 
 parallel to c d, or at right angles to B e, and through the points, 1, 2, 3, 
 draw k I, m n, o p, and tracing a curve through the points d, p, n, I €, 
 and making d o m k B similar, then the space comprehended between the 
 curve lines dJi e ; and the side BC of the plan, will give the form of the 
 whole covering, for each side of the dome. 
 
 To find the hip- line of the angle-rib, whose base is C c. 
 
 Draw CE, 2e, If, at right angles to C e, and make CE equal to eb. 
 
2^eeU &Stoc^d^ scJ:> z Sntmd 
 
1 
 
 I 
 
 I 
 
and machinist. 
 
 ^77 
 
 2 (? equal S-'S, and 1 /equal to 1, 2, &c. and trace the curve through these 
 points, and it will give the angle-rib. 
 
 The method of covering spherical domes is, to suppose 
 them polygonal, and the principle the same as the foregoing 
 operation for an octangular dome. 
 
 A in carpentry, is the wood-work to be lathed over 
 
 for plastering. The general construction of niches is with 
 cylindrical backs and spherical heads, called cylindro-sj^heric 
 niches ; the execution of which depends upon the principles 
 of spheric sections. 
 
 As every section in a sphere is a circle, and that section 
 passing through its centre is equal, and the greatest that 
 can be formed by cutting the sphere ; it is evident, that if 
 the head of a niche is intended to form a spherical surface, 
 the ribs may be all formed by one mould, whose curvature 
 must be equal to that of the greatest circle of the sphere ; 
 viz. one passing through its centre ; but the same spherical 
 surface may, though not so eligible, be formed by ribs of 
 wood, moulded from the sections of lesser circles, in a 
 variety of ways. 
 
 The reason why these latter spherical surfaces are not so 
 eligible as those of greater circles is, because their dispo- 
 sition for sustaining the lath is not so good, and the trouble 
 of moulding them to different circles, and of forming the 
 edges according to different bevels, in order to range them 
 in the spherical surface, is very great, compared with those 
 made from great circles. 
 
 Tne disposition of the ribs of niches is generally in a 
 vertical plane, parallel to each other, or intersecting each 
 other in a vertical line. When the line of intersection 
 passes through the centre of a sphere, all the ribs are great 
 circles ; but if the line of intersection does not pass through 
 the centre of the sphere, the circles which form the sphe- 
 rical surface are all of different radii. When the ribs are 
 fixed in parallel vertical planes, their disposition is either 
 parallel to the face of the wall, or parallel to a vertical 
 plane, passing through the centre of the sphere, perpendi- 
 cular to the surface of the wall ; but this method is not so 
 eligible for the purposes of lathing. 
 
 Another method is, by making the planes of the ribs pa- 
 rallel to the horizon ; this is not only attended with great 
 labour in workmanship, but is incommodious for lathing. 
 The various positions in which the ribs of a niche may be 
 placed, are very numerous ; but the regular positions, al- 
 
 2 p 
 
THE OPERATIVE MECHANIC 
 
 578 
 
 ready enumerated, ought to be those to which the carpenter 
 should direct his attention. 
 
 To get out the ribs for the head of a niche, all of them being 
 hi vertical planes passing through the centre of the sphere, 
 
 Fi^. 591, No. 1. From the centre C draw the ground-plan of the ribs, 
 and set out as many ribs upon the plan as you intend to have in the head 
 of the niche. With the foot of your compasses in C, and from the ends of 
 each rib, at k and /, draw the small concentric dotted circles round to the 
 centre rib, at o and p, and draw o m, and p w, parallel to a b, the face of 
 the wall ; then from r round to s on the plan is the length and sweep of 
 the centre rib to stand over ; and from n round to s the length and curve 
 of the rib that stands from b to g ; and from m round to s, the curve of 
 the shortest rib, that stands from A: to A on the plan. 
 
 Uotu to find the bevel of the ends of the back ribs against 
 the front rib. 
 
 The back ribs are laid down distinct by themselves, at AB and C from 
 the plan. Take b 1, in No. 1, and set it to A 1, at B, draw the perpen- 
 diculars, and when they intersect the rib, it will show the bevel required. 
 The same operation being done to C, the bevel is found in the same manner. 
 
 The places of the back-ribs when fixed upon the front- 
 rib are ascertained by drawing perpeiiu eulars, and com- 
 pleting the elevation of the niche No. 2 from the plan. 
 
 To find the radius of curvature of the ribs of a spherical 
 niche, tvhen the ribs all meet in a vertical line, which di- 
 vides the front rib into two equal parts. 
 
 Fig. 592, No. 1. Complete the circle, of which the inside of the plan is 
 an arc ; produce the middle line of the plan of any rib, as of a A, to meet 
 the opposite side of the circumference in A ; on the whole line a A, as a 
 diameter, describe a semicircle, and from the point c, when the ribs in- 
 tersect, draw a perpendicular to c </, to meet the arc a rf at which arc 
 is the curve of the rib, whose seat is d. The other rib, as AD, is found 
 in the same manner. No. 2 is the elevation of the niche. 
 
 Pendentive cradling, is a cove bracketing, springing from 
 the rectangular walls of an apartment upwards to the ceil- 
 ing, so as to form the horizontal part of the ceiling into a 
 complete circle or ellipsis. 
 
 The proper criterion for such bracketing, if the walls are 
 out by horizontal planes through the coved parts, is, that 
 all the sections through such parts will be portions of cir- 
 cles, or of ellipses, and have their arcs proportioned to the 
 sides of the apartment, so that each section will be a 
 compound figure. Besides having four curvilinear parts, it 
 will have four other parts, which are portions of the sides 
 of the rectangular apartment : and the axis of the ellipsis 
 will bisect each side of the rectangle. 
 
 Fig. 593. Let ABCD be the plan of a room, or stair-case, to be brack- 
 
AND MACHINIST. 
 
 579 
 
 •ted, so as to form tlie surface of a peiidentive ceiling- ; and let A 6 c D be 
 the section across the diagonal ; it is required to find the curvature of the 
 springing ribs ? 
 
 Draw C d perpendicular to AC, meeting AC, take the distance from C 
 to tJie line AC, and set it from Con the line CA, and from this point draw 
 a perpendicular to meet the curve \ I e D of the diagonal rib ; make the 
 versid sine of the segment A </ C equal to this perpendicjjlar, and describe 
 the segment A d C, which is the springing line required. If from the 
 centre C an arc be described, with a radius equal to the length of the seat 
 of a rib, to meet the seat of the diagonal rib AD ; and, if from the point 
 of meeting a perpendicular be drawn to meet the curve A b, the portion of 
 the arc of the diagonal rib, intercepted between A and the perpendicular, 
 will give the length of the rib, corresponding to the seat which was taker.. 
 
 Fig. 594. The diagonal rib is a semicircle: the operation is exactly the 
 same, and may be described in the same words. 
 
 MENSURATION OF CARPENTERS* WORK. 
 
 All large and plain articles in which an uniform quantity 
 of materials and workmanship is expended, are generally 
 measured by the square of 100 superficial feet. 
 
 Piles used in the foundations are valued at per piece, and 
 driven by the foot run, according to their diameter, and 
 the quality of the ground. 
 
 Keepers and planking are measured by taking the super- 
 ficial contents in yards or squares. 
 
 Plain centreing is measured by the square ; but as the 
 ribs and boarding are two different qualities of work, they 
 ought to be measured and valued separately ; one dimension 
 of the boarding being taken by girting it round the arch, 
 the other being the length of the vault. 
 
 Centreing for groins should be measured and valued as 
 common centreing ; but in addition thereto, the angles 
 should be paid for by the foot run, that is, the ribs and 
 boarding ought to be measured and valued separately, ac- 
 cording to the exact superficial contents of each ; and the 
 angles by the lineal foot for workmanship, in fitting the 
 rib and boards, and for the waste of wood occasioned by 
 the operation. 
 
 Wall-plates, lintels, and bond-timbers, are measured by 
 the cubic foot, under the denomination of fir-in-bond. 
 
 Naked flooring may either be measured by the square, 
 or by the cubic foot, according to the description of the 
 work, and the quantity of timber employed. In forming 
 an estimate of its value, it should be observed, that in equal 
 cubic quantities of small and large timbers, the small tim • 
 
 2 p 2 
 
:>8o 
 
 THE OPERATIVE MECHANIC 
 
 bers will have more superficies than the large ones^ and, 
 therefore^ the saving will not be in a ratio with the solid 
 contents ; consequently the value of the workmanship will 
 not follow the cubic quantity, or said ratio. The difficulty 
 of handling timbers of the same length increases with the 
 weight or solidity, as the greater quantity requires greater 
 power to handle it, and consequently more time. 
 
 In naked flooring, where girders are introduced, the uni- 
 formity of the \vork is interrupted by mortises and tenons, 
 so that the sum ascertained by the cubic quantity of the 
 girders, at the same rate per foot as the other parts, is not 
 sufficient ; not only on account of the great difference of 
 size, but the great disparity in the quantity of workman- 
 ship, occasioned by its being cut full of mortises to receive 
 the tenons of the binding-joists ; the best method, there- 
 fore, to value the labour and materials is, to measure and 
 estimate the whole by the cubic quantity, and allow an addi- 
 tional rate upon every solid foot of girders ; or, if the bind- 
 ing-joists are not inserted in the girders, at the usual dis- 
 tances, a fixed price for every mortise and tenon, in pro- 
 portion to their size, which will keep a ratio with the area 
 of the end of the girder. 
 
 Partitions may be measured by the cubic feet ; but the 
 cills, top-pieces, and door-heads, should be measured by 
 themselves, according to the solid quantity, at an additional 
 rate ; because, both the uniform solidity, and the uniform 
 quantity of workmanship are interrupted by them. In 
 trussed partitions, the braces should be rated by the foot 
 cube, at a superior price to that of the quarterings, for the 
 trouble of fitting the ends of the uprights upon their upper 
 and lower sides, and for forming the abutments at the ends. 
 
 The timbers in roofing should be measured by the cubic 
 foot, classed as the difficulty of execution, or as the waste 
 occasioned, may require. 
 
 Battening to walls is best measured by the square, ac- 
 cording to the dimensions and distances in the clear of the 
 battening. 
 
 It w'ould be endless to enumerate the various methods 
 of measuring each particular species of carpenters' work ; 
 the leading articles only need be noticed. 
 
 When the shell of a building is finished, that is, previous 
 to the floors being laid, or the ceilings lathed, all the timbers 
 should be measured, that no doubt may arise as to the actual 
 scantlings of the timbers, or of the description of the work- 
 manship. In taking dimensions it must be observed that, 
 
AND MACHINIST. '581 
 
 alJ pieces which have tenons^ must be measured to the extre- 
 mities of the tenons. 
 
 It is impossible to determine on any proper rate, includ- 
 ing both materials and workmanship, as the one may be 
 stationary, while the other is variable. With respect to 
 materials, the value of any quantity may be easily ascer- 
 tained, whatever be the price per load ; but the difficulty is 
 far greater in fixing proper rates of \vorkmanship ; however, 
 were the time of executing every species of work known, 
 there would be no difficulty in establishing certain uniform 
 quantities^ which would give the real value. 
 
 JOINERY. 
 
 Is the next branch of art which comes under our con- 
 sideration, and comprises the practice of employing wood in 
 the external and internal finishings of houses. 
 
 In the execution of this branch of building, it is almost 
 unnecessary to observe that, as joinery is employed princi- 
 pally by way of decoration, and is liable to close inspection, 
 it is one of the departments which demands the strictest 
 care and attention in the ^vorkmen; and it requires the 
 greatest ingenuity, skill, and experience, to become fully 
 master of every subject under the joiner’s consideration. 
 
 The first and most important thing to be attended to, is 
 the judicious selection of materials ; as, without a strict ob- 
 servance of this particular, the care, ingenuity, and ex- 
 ertions of the workman will be wholly frustrated. 
 
 As the temperature of the atmosphere has a great influ- 
 ence on wood, and more particularly in the winter sea- 
 son, it would be advisable to put that which is to be 
 used in fine work over an oven for a day or two. In the 
 different descriptions of joint used by the joiner, a hot 
 tenacious liquid, called glue^ is almost universally used, and 
 when applied, the two surfaces of the wood, which have been 
 previously rendered smooth, are rubbed together until the 
 glue is nearly all forced out. One piece is then set to its 
 situation with respect to the other. 
 
 For outside work, such as gates, dobrs, &c. white-lead is 
 used in all the joints. 
 
 When a frame, consisting of several pieces, is required, 
 the mortises and tenons are fitted together, and the joints 
 glued all at one time, then entered to their places, and forced 
 together by the assistance of an instrument called a cramp. 
 
682 
 
 THE OPERATIVE MECHANIC 
 
 The operation of rendering a rough surface smooth, by 
 taking away the superfluous wood, is called planing ; and 
 the tools used for this pui’pose are called planes. 
 
 The planes used by joiners in the primary operation of 
 their work are called jack-planes^ trying-planes, long- 
 planes, and smoothing-planes ; the respective uses of which 
 are as follow : — ^The jack-plane is used for taking away the 
 rough occasioned by the saw, and removing all superfluous 
 and other uneven parts. The trying-plane more par- 
 ticularly to bring the surface perfectly level and true : the 
 long plane succeeds, when the surface is long, and is re- 
 quired to be very straight, as in jointing long boards for 
 the purpose of gluing them together; and the smoothing- 
 plane is used to smooth and clean off the work. 
 
 In addition to the above, termed hench-planes, others are 
 occasionally used in forming any kind of prismatic surfaces, 
 viz. rehating-planes, grooving-pflanes, moulding-planes, &c. ; 
 under which head is included the fillister and plough, 
 
 Rehating-planes arc used for cutting out rebates, a kind 
 of half groove, upon the edge of a board, or other piece of 
 wood, formed by taking down or reducing a small part of 
 the breadth of the board to half, more or less, of the general 
 thickness. By this means, if a rebate be cut on the upper 
 side of one board, and the lower side of another, the two 
 may be made to overlap each other, without making them 
 any thicker at the joint. 
 
 Rebates are also used for ornamenting mouldings, and for 
 many other purposes in joiners^ work. The planes for cut- 
 ting them are of different kinds, some having the cutting 
 edge at the side of the iron and stock ; others at the bottom 
 edge of the iron and the face of the stock ; and others cut- 
 ting in both these directions. The former are used to 
 smooth the side of a rebate, and therefore are called side 
 rehating-planes ; the others for smoothing the bottom. A 
 third sort of rebate-planes, called a fillister, is used for 
 sinking or cutting away the edge of a piece of wood, to form 
 the rebate, leaving it for the others to smooth the surfaces 
 when cut. 
 
 The moving fillister is a rebating- plane having a ruler of 
 wood, called \\\ct fence, fixed by screws, upon its face, in the 
 direction of its length, and exactly parallel to the edge of 
 the face ; consequently, it covers part of the width of the 
 cutting edge, and can be fixed at any required distance from 
 the edge, to leave more or Rss of the cutting edge exposed, 
 which will be the breadth of the rebate it will cut, because. 
 
AND MACHINIST. 
 
 683 
 
 wnen used, the edge of the fence is applied against the edge 
 of the piece to be rebated, and thus gauges the breadth its 
 iron should cut away. The cutting-iron of this plane is not 
 situated at right angles to the length of the stock, but has 
 an obliquity of about forty-five degrees ; the exposed side 
 of the iron being more forward than the one next to the 
 fence. By this obliquity, the plane has a tendency or drift 
 to run further into the breadth of the wood ; but as the fence 
 sliding against the edge prevents this, the drift always keeps 
 the fence in contact with the piece without the attention of 
 the workman : it also causes the iron to cut the bottom of 
 the rebate smoother, particularly in a transverse direction 
 to the fibres, or where the wood is cross-grained, or where 
 the edge is perpendicular to the sides of the plane. It is 
 chiefly used, however, to throw the shaving into a cylindri- 
 cal form, and thereby make it issue from one side of the 
 plane. Besides this iron, there is another of smaller di- 
 mensions, called the toothy which precedes the other, to 
 scratch or cut a deep crack in the width of the rebate, thus 
 making the shaving, which the iron cuts up from the bot- 
 tom, separate sideways from the rest of the wood. The 
 sash-fillister differs in many particulars from the moving- 
 fillister : the fence is adapted to be moved to a considerable 
 distance, not being fixed, as in the moving fillister, by 
 screws upon the face, but sustained by two bars, fixed fast to 
 it, passing through the two vertical sides of the stock at 
 right angles to the sides : these bars, when set to their 
 intended places, are tightened by small wedges. This kind 
 of plane is usually employed to rebate narrow pieces of 
 wood, such as are used in sashes ; and the fence is applied 
 against the opposite edge to that on which the rebate is to 
 be formed. 
 
 plough is a plane with a very narrow face, made of 
 iron, fixed beneath a wooden stock, and projecting down 
 from the wood of the stock ; the edge of the cutting-iron 
 being the full width of the groove required : it is guided by 
 a fence with bars like the sash-fillister, and has also a stop to 
 regulate the depth intended for the grooves. 
 
 Moulding-planes are those which have their faces and 
 cutting edges curved, to produce all the varieties of orna- 
 mental mouldings : they are known by the names of snipe' s- 
 hills, side snipe* s-hills, beads, hollows, rounds, ovolos, and 
 ogees. Of these there are a great variety of sizes, with which 
 every good joiner is furnished. 
 
 The whole of these planes have their faces straight in the 
 
584 
 
 THE OPERATIVE MECHANIC 
 
 direction of their length ; but a section across the face is 
 the impression or reverse of the moulding they are intended 
 to make. 
 
 The tools employed in boring cylindric holes are a stock 
 with hits^^ gimlets, and of various descriptions and 
 
 sizes. Tne tools used for paring the wood obliquely, or 
 across the fibres, and for cutting rectangular prismatic ca- 
 vities, are in general denominated chisels ; those for paring 
 the wood across the fibres being called firmer s, or paring- 
 chisels, and those for cutting mortises, mortise- chisels. The 
 best paring-chisels are made entirely of cast steel. Chisels 
 for paring concave surfaces, are called gouges. 
 
 Wood is generally divided or reduced by means of saivs, 
 of which there are several sorts; as the ripping- saw, for 
 dividing boards into separate pieces, in the direction of the 
 fibres ; the hand-saw, for cross-cutting, or for sawing thin 
 pieces in the direction of their length ; the panel-saw, either 
 for cross cutting, or cutting very thin boards longitudinally ; 
 the tenon-saw, with a thick iron back, for making an inci- 
 sion of any depth below the surface of the wood, and for 
 cutting pieces opposed to the length of the fibres ; also a 
 sash-saw, and a dovetail-saw, used much in the same way 
 as the tenon-saw. 
 
 From the thinness of the plates of these three last-men- 
 tioned saws, it is necessary to stiffen them by a strong piece 
 of metal called the back, which is grooved to receive the 
 upper edge of the plate, fixed to the back, and which is 
 thereby secured and prevented from crippling. 
 
 When it is required to divide boards into curved surfaces, 
 a very narrow saw without a back, called a compass-saw, 
 is used ; and in cutting a very small hole, a saw of a similar 
 description is used, called a key-hole-saw . Both of these 
 description of saws are called turning- saws, and have ‘their 
 plates thin and narrow towards their bottoms, and each 
 succeeding tooth finer. 
 
 The external and internal angles of the teeth of all saws 
 are generally formed at one angle of 60 degrees, and the 
 fi out edge teeth slope backwards in a small degree. The 
 teeth of every description of saw, except turning-saws, are 
 alternately bent on contrary sides of the plate, so that all 
 the teeth on the same side are alike bent throughout the 
 length of the plate, for the purpose of clearing the sides of 
 the cut made by it in the wood. The foregoing are generally 
 termed edge-tools. 
 
 U^hen it is necessary to ascertain if an angle be exactly 
 
AND MACHINIST. 
 
 585 
 
 square, or inclined to any number of degrees, a tool called 
 a square is used, and in the latter instance, a bevel is set to 
 the angle ; when any piece is to be reduced to a parallel 
 breadth or thickness, an instrument, called a gauge, formed 
 of a square piece with a mortise, having a sliding bar, called 
 a stem, running through it at right angles, and furnished 
 with a tooth, projecting a little from the surface, is used ; 
 so that when the stock of the gauge is applied to the verti- 
 cal side or edge of the piece, with the toothed side of the 
 stem upon the horizontal surface, and is pushed and drawn 
 alternately backwards and forwards by the workman, the 
 tooth will make an incision from the surface into the wood, 
 at a parallel distance from the edge to which the stock part 
 ii> applied. 
 
 When a mortise is to be made in a piece of wood, the 
 gauge used has two teeth. The construction of this gauge 
 is the same as that before described, except that the tooth 
 nearest the stock moves by means of a longitudinal slider 
 in the stem, wdiich is to be set at a distance from the other 
 tooth, as occasion may require. 
 
 If a piece of wood is to be sawn across the fibres, a flat 
 piece of wood, which has two projecting knobs, on opposite 
 sides, one at each end, called a side-hook, is used, to keep 
 the piece which has to undergo the operation of the saw 
 steady ; the knob at one end presses against the piece, while 
 that at the other end is hooked to the bench. Two of 
 these are necessary when the pieces are long. • 
 
 When a piece of wood is required to be cut to a mitre, 
 that is, to half a right angle, joiners use a trunk of wood 
 with three sides, like a box that has neither ends nor top, the 
 sides and bottom being parallel pieces, and the sides of equal 
 height. Through each of the opposite sides, in a plane per- 
 pendicular to the bottom, and at the oblique angles of 45° 
 and 135° with the planes of the sides, a kerf is cut ; and 
 another kei'f is made with its plane at right angles to the 
 two former. Into this trunk, termed a mitre-hox, the piece 
 to be cut is put, and the saw, guided by the kerfs, cuts the 
 wood to the angle required. 
 
 In making a straight surface, a strip of wood called a 
 straight-edge, which has one of its edges perfectly straight, 
 is frequently applied, to detect the irregularities, and the 
 piece is accordingly planed with the trying plane until the 
 surface coincides with the straight-edge. 
 
 To ascertain if. the surface of a piece of wood be in one 
 plane, the joiner takes two slips of wood, each straightened 
 
580 
 
 THE OPERATIVE MECHANIC 
 
 on one edge, with the opposite edge parallel, and both 
 pieces of the same height, and places them one at each end, 
 across the board under operation ; he then looks in the lon- 
 gitudinal direction of the board over the upper edges of the 
 slips, and if the two edges and his eye be not in one plane, 
 the upper parts are planed down until the piece is said to be 
 out of luind, and the same term is applied to the slips, which 
 are called winding-sticks. The operation of making the 
 edge of a board straight is called shooting ; and the edge so 
 made is said to be shot. 
 
 From what has been here said of the application of the 
 ])rincipal tools used by the joiner, we consider any further 
 account of the primary processes unnecessary 5 we shall, 
 tlierefore, proceed to lay before the reader the best methods 
 in use of effecting some of the more difficult and particular 
 operations. - 
 
 To construct the surface of a portion of a cylinder with 
 wood^ when the fibres are at right angles to the axis of the 
 cylinder^ such as may he used in a circular dado, or the sof- 
 fits of windows. 
 
 If the dimension of the cylindric surface, parallel to the 
 axis, be not broader than a plank or board, this may be 
 done by gluing several thicknesses of veneer upon each 
 other ; the first upon a mould, or upon brackets, with their 
 edges in the surface of the proposed cylinder, parallel to its 
 axis. This may be effected by means of two sets of brackets 
 fastened to a board, one convex and of the curve intended, 
 and the other concave of the curve of the exterior of the 
 whole thickness of veneers, or somewhat larger ; this last 
 bracket is then applied on the top of the veneers and fas- 
 tened to the other bracket, and the veneers are then forced 
 together by means of wedges between the concave brac- 
 ket and the veneer. If this operation be carefully done and 
 the glue properly dried, the wedges may be slackened and 
 the work will stand well, but it must be observed, that, as 
 the wood has a natural tendency to unbend itself, the curved 
 surface, upon which it is glued, should be rather quicker 
 than that intended to be made. 
 
 A second plan is to form a templet or cradle to the sur- 
 face intended, and lay a veneer upon it ; then to glue a num- 
 ber of blocks of wood upon its back, closely fitted to its 
 surface, and the other joints to each other, the fibres of the 
 veneer being parallel to those of the blocks. 
 
 A third method is to make a cradle and place the veneer 
 upon it, coiifiriing one end; lay the glue between the 
 
AND MACHINIST. 
 
 587 
 
 veneers with a brushy and fix a bridle across^ confining its 
 ends either by nails or by screws ; open the veneers again, 
 put glue a second time between each, and fix another bridle 
 across them 5 and in this manner proceed to the other ex- 
 tremity. 
 
 A fourth plan is to cut a number of equidistant grooves 
 across the back of the board, at right angles to its edges, 
 leaving only a small thickness towards the face; then to bend 
 this round a cradle with the grooves outwards, and fill the 
 grooves with strips of wood, which, after the glue is quite 
 dry, must be planed down level with the surface of the 
 board. This may be stiffened by gluing strong canvass on 
 the back. 
 
 To hend a hoard so as to form the frustum of a cone, or 
 any segmental portion of the frustum of a cone, as the sof- 
 fit of the head of an aperture. 
 
 When the envelope of the covering is found by the rule 
 laid down under the article Masonry, page 542, and 
 the mould is made with a thin piece of board, cut out the 
 board intended to be bent, and run a number of saw kerfs, 
 or grooves made by a plane, (which are preferable,) equi- 
 distant from each other, and tending to the centre, and 
 having fixed it to a templet, made to the surface of a cone, 
 finish it in the manner shown in the last method, for a 
 cylinder. 
 
 To glue up the shaft of a column, supposmg it to be the 
 frustum of a cone. 
 
 Prepare as many staves as the circumference may require, 
 and let the joints of each be so managed as to fall in the fil- 
 lets, which disposition will be stronger than if they were to fall 
 in the middle of the flutes. Suppose eight pieces to be suf 
 ficient to constitute the shaft of a column : describe a circle 
 to the diameterof each end; about each circle describe an octa- 
 gon ; from the concourse of each angle draw aline to the cen- 
 tre, then draw an interior concentric octagon, with each side 
 parallel to the respective sides of the corresponding one, 
 and the distance between these two octagons equal to the 
 thickness of the staves ; and thus the section of the staves 
 will be found at each end, and consequently, the bevels will 
 be obtained throughout the whole length. In order to join 
 the column, glue two pieces together, and when quite dry, 
 glue in blockings to strengthen them ; join a third piece to 
 the former two, and secure it also by blockings. In this 
 manner proceed to the last piece but one. In fixing the last 
 piece^ the blockings must be idued to the adjacent sla\es; 
 
588 
 
 THE OPERATIVE MECHANIC 
 
 and their surfaces, on which the last stave is intended to 
 rest, must be all in the same plane, that its back may rest 
 firmly upon them. In closing up the remaining space, the 
 part of the Qolumn that is glued together should be kept 
 from spreading by confining it in a kind of cramp, or cra- 
 dle, while driving the remaining stave to close the joints. 
 
 Instead of the foregoing mode, some joiners glue up the 
 columns in halves and then glue them together. When an 
 iron core is necessary to support a floor or roof, the column 
 must necessarily be glued up in halves ; in which case the 
 two halves are to be dowelled together, and the joints filled 
 with white-lead. Instead of a cramp, a rope is used, 
 twisted by means of a lever. In bringing the two halves 
 together, the percussive force of the mallet must be applied 
 upon the middle of the surface of one half, while an assist- 
 ant holds something steady against the middle of the other, 
 that the opposition may be equal, and by this means the 
 surfaces will be brought into contact, and form the joint 
 as desired. In this operation pieces of wood ought to be in* 
 serted between the column and the rope. 
 
 Boards can be connected together at any given angle, 
 either by pins or nails, mortise and tenon, or by indenting 
 them together. 
 
 This last mode, from the sections of the hollows and pro- 
 jecting parts being formed like a dove’s tail, is called dove-- 
 tailing. 
 
 There are three sorts of dovetailing}, viz. common, lap, 
 and mitre. Common dovetailing shews the form of the 
 projecting parts, as well as of the excavations made to re- 
 ceive them ; lap dovetailing conceals the dovetail, but shews 
 the thickness of the lap on the return side j and mitre dove- 
 tailing conceals the dovetail and shews only a mitre on the 
 edges of the planes at the surface of the concourse ; that is, 
 the edges in the same plane, the seam or join being in the 
 concourse of the two faces, making the given angle with 
 each other. 
 
 Concealed dovetailing is particularly useful where the faces 
 of the boards are intended to form a saliant angle ; but 
 when the faces form a re-entrant angle, common dovetailing 
 is preferable. 
 
 There is another simple and expeditious manner of con- 
 necting the ends of boards together where the faces form a 
 re-entrant, or internal angle, by means of a groove in the 
 one, and a tongue in the other ; and if the pieces be pre 
 
AND MACHINIST. 
 
 589 
 
 viously nailed so that the nails be not seen in the faces^ inis 
 will answer every purpose of common -dovetailing. 
 
 As various methods are employed in connecting pieces of 
 wood so as to form an angle, we shall here present the 
 reader with so.ne of the best examples. 
 
 Fi^s. 595 and 596 are methods of connecting two pieces of wood so as 
 to form two internal right angles. 
 
 Figs. 597, 598, 599, 600, 601, and 602, exhibit the joining of boards at 
 an external angle. 
 
 In Figs. 598 and 599 the external angle, being that which is exposed 
 to sight, is rounded or beaded. 
 
 Fig. 600 is the most common of mitres. 
 
 Fig. 601, a lapped mitre, which is much stronger than Fig. 600. 
 
 Fig. 602, a lapped andtongued mitre. 
 
 Fig. 603, dovetailing. 
 
 Fig. 601, secret dovetailing. 
 
 If several boards are required to be joined together to 
 form a broad face, they are sometimes strengthened by fix- 
 ing, with a tongue and groove, or mortise and tenon, 
 another narrow piece across each end : the cross piece is 
 termed a clamp, and the board thus constructed is said to 
 be clamped. 
 
 The most simple description of door is constructed of 
 several boards simply rebated together, or each edge plough- 
 ed and tongued ; these are confined together by a transverse 
 piece, called a ledge nailed a cross, from which the door de- 
 rives the name of a ledge-door. 
 
 When strength, durability, and beauty are to be combined, 
 a frame, joined by mortise and tenon, is constructed with 
 one or more openings ; and these openings are filled with 
 pieces called panels, fitted into grooves, ploughed in the 
 edges of the frame. The horizontal pieces of the framing are 
 called, according to their situation, top-rail, bottom-rail, 
 lock-rail, and frieze-rail. On the lock- rail the lock is either 
 mortised in, or screwed on ; and the frieze-rail is an interme- 
 diate rail between the top and middle rail. The extreme 
 vertical pieces to which the rails are fixed are called stiles ; 
 and if there be any intermediate piece it is called a 
 mounting. 
 
 Doors derive their names according to the manner in 
 which they are framed and the number of panels they con- 
 tain, as one, two, four, six, &c. panelled doors ; and are 
 further described by the moulding and description of panel. 
 
 Jib-doors are those which, when shut, are as much con- 
 cealed as possible. They are used to preserve the uni- 
 formity of a room, or to save the expense of a corresponding 
 
590 
 
 THE OPERATIVE MECHANIC 
 
 door. Doors ought to be made of the best materials, per- 
 fectly seasoned, and firmly put together ; the mitres or 
 scribings should be brought together with the greatest ex- 
 actness, and the whole of their surfaces be perfectly smooth. 
 
 The mortising, tenoning, ploughing, and sticking of the 
 mouldings, ought to be worked correctly to the gauge-lines ; 
 otherwise the door, when put together, will be out of 
 truth, and occasion the workman a great deal of trouble, 
 paring the different parts to make it appear satisfactory : 
 the door will also lose much of its firmness, especially if the 
 mortises and tenons require to be pared. 
 
 In bead and flush doors, make the work square, after- 
 wards put in the panels, and smooth the whole off to- 
 gether ; then, marking the panels at the parts of the fram- 
 ing to \vhich they agree, take the door to pieces, and work the 
 beads on the stiles, mountings, and rails. If the doors are 
 tloubie margin, that is, representing a pair of folding doors, 
 the staff stile, which imitates the meeting-stiles, must be 
 inserted into the top and bottom rails of the door, by fork- 
 ing the emls into notches cut in the top and bottom rails. 
 
 In the hanging of doors, the chief aim is to clear the car- 
 pet or ground; which may be accomplished by observing 
 the following rules. First, let the floor be raised under the 
 door, according to the intended thickness of the carpet ; 
 secondly, let the knuckles of the top and bottom hinges be so 
 placed, that the top hinge hang, or project, about one 
 eighth of an inch over the lower ; that is, if the hinge be let 
 equally into the door and into the jamb, project a little be- 
 yond the surface of the door ; but if the centre lie in the 
 surface of the door, it must be placed at the very top, which 
 is seldom done, except when the door is hung with centres. 
 Thirdly, let the jamb on which the door hangs, be fixed 
 about an eighth of an inch out of the perpendicular, the 
 upper part inclining towards the opposite jamb ; and 
 fourthly, let the inclination of the rebate be such, that the 
 door shall, when shut, project at the bottom, towards the 
 room, about an eighth of an inch. 
 
 These several methods, practised on so small a scale, are 
 not perceptible ; but, nevertheless, will throw the door, 
 when opened, to a square sufficiently out of the level ; that 
 is, at least half an inch, when the height of the door is 
 double the width. 
 
 Several kinds of rising hinges have been introduced for 
 this purpose : some of the best, constructed of brass, are by 
 no means objectionable, even to the best doors. 
 

 FL.85 
 
 nr^l, sc JS I SmmJ 
 

AND MACHINIST. 
 
 591 
 
 Before we proceed to the principles of hanging doors, we 
 shall submit to the reader some information on the subject 
 of hinging in general. 
 
 The placing of hinges depends entirely on the form of the 
 joint, and as the motion of the door or closure is angular, and 
 performed round a fixed line as an axis, the hinge must be 
 so fixed that the motion be not interrupted : thus, if the joint 
 contain the surface of two cylinders, the convex one in mo- 
 tion upon the edges of the closure, and sliding upon the 
 concave one which is at rest on the fixed body, the motion 
 of the closure must be performed on the axis of the cylin- 
 der, which axis must be the centre of the hinges. In this 
 case, whether the aperture be shut or open, the joint will be 
 close ; but if the joint be a plane surface, it is necessary to 
 consider upon what side of the aperture the motion is to be 
 performed, as the hinge must be placed on the side of the 
 closure where it revolves. 
 
 The hinge is made in two parts, movable in any angular 
 direction, the one upon the other. 
 
 The knuckle of the hinge is a portion contained under a 
 cylindric surface, and is common both to the moving part 
 and the part which is at rest ; the cylinders are indented in- 
 to each other, and are made hollow to receive a concentric 
 cylindric pin, which passes through them, and connects the 
 moving parts together. 
 
 The axis of the cjdindrical pin, is called the axis of the 
 hinge. 
 
 When two or more hinges are placed upon a closure, the 
 axis of the hinges must be in the same straight line. 
 
 The straight line in which the axis of the hinges are placed 
 is called the line of hinges. 
 
 We shall now proceed to the principle of hanging doors, 
 shutters, or flaps, with hinges. 
 
 The centre of the hinge is generally put in the middle of the joint, as 
 at A, Fig. G05, but in many cases there is a necessity for throwing back 
 the flap to a certain distance from the joint ; in order to eflect this, sup- 
 pose the flap when folded back, were required to be at a certain distance 
 from the joint, as BA, Fig. G05, divide BA in two equal parts at the point 
 C, and it will give the centre of the hinge. The centre of the hiiige 
 must be placed a small degree beyond the surface of the closure, other- 
 wise it will not fall freely back on the jamb, or partition. It must also be 
 observed, that, the centre of the hinge must be on the same side as the re- 
 bate, or it will not open without the joint being constructed in a particu- 
 lar form. 
 
 To hajig two flaps, so that ivhen folded hack, they shall he 
 at a certain distance from each other. 
 
 This is easily accomplished by means of hinges having knees project- 
 
592 
 
 I'HK OPERATIVE MECHANIC 
 
 ing’ to half that distance, as appears from Fig-. GOT: this sort of hinge is 
 used in hanging the doors of pews, in order to clear the moulding of the 
 coping. Fig. 607, No. 2, shows the same hinge opened. 
 
 To make a rule joint for a ivindow-shutter, or other fold- 
 ingflap. 
 
 60S, No. 1. Let a be the place of the joint, draw a c at rig’ht an- 
 gles to the flap, shutter, or door, take c, in the line a c, for the centre of 
 the hinge, and the plain part a b, as may be thought necessary ; or c, with 
 a radius, c by describe the arc b d ; then will a b d be the true joint. 
 The knuckle of the hinge is always placed in the wood ; because the further 
 it is inserted, the more of the joint will be covered when it is opened to a 
 right angle, as in Fig. GOG, No. 2; but if the centre of the hinge were 
 placed the least without the thickness of the wood, it would show an cpen 
 space, which would be a blemish. 
 
 To form the joints of stiles, to he hung together, when the 
 knuckle of the hinge is placed on the contrary side of the 
 rebate. 
 
 Fig. G08. Let c be the centre of the hinge, m i the joint on the same 
 side, c h the depth of the rebate in the middle of the thickness of the styles, 
 perpendicular to i m, and If the joint on the other side, parallel toim; 
 bisect i I at k, join k c, on k c describe a semicircle c iky cutting i?n at A, 
 through the points h and k draw h k g, cutting / 1 aXg; then will f gyh my 
 be the true joint. 
 
 Fig. GOO represents the common method of hanging shutters together, 
 the hinge being let the whole of its thickness into the shutter, and not into 
 the sash-fr.ame. By this mode it is not so firmly hung as when half of it 
 is let into the shutter, and half into the sash-frame ; but the lining may be 
 made thinner. 
 
 It may here be proper to observe, that the centre of the 
 hinge must be in the same plane with the face of the shut- 
 ter, or beyond it, but not within the thickness. 
 
 Hoiv to construct a joint for hangmg doors with centres. 
 
 Fig. G14. Let a d be the thickness of the door, bisect it in by draw b c 
 perpendicular to a by make b c equal to b a, or h dy or c, the centre of the 
 hinge, with a radius c «, or c dy describe an arc, a e dy which will give 
 the joint required. 
 
 Another plan is represented in Fig. 613. Draw a b parallel to the jamb, 
 meeting the other side in by make b d equal to h «, and join a d and a c, bi- 
 sect « c by a perpendicular e /, meeting a d in/, then / is the centre of 
 the liiiige. 
 
 Figs. 610, 611, and 612, exhibit different methods of hanging flaps, 
 &c. These are so very simple, that by a little attention the reader will 
 y cadily perceive their uses and manner of construction. 
 
 We shall now detail the construction of sash-frames, 
 sashes, and shutters, and the manner of putting the several 
 parts together. 
 
 Fig. 615, No. 1, the elevation ; No. 2, the plan ; and No. 3, the section 
 of the same ; showing the manner in which the different parts are eon- 
 1 ected. 
 
Ir om 6l5 to 6l 7 
 
 PIM 
 
 b'lo^ 
 
 StriaU 
 
AND MACHINIST. 
 
 593 
 
 No. 1 . A Backi— B Flush skirting:, separated from the back by flush 
 reeds, and showing: the same depth of plinth as the blocks of the pilas- 
 ters. — C C Blocks or plinths to pilasters. — D D Pilasters. — E E Patteras. 
 — a a aa Inside bead of sash-frame . — b b b rounded edge of boxing-stile. 
 
 No. 2. Plan of sash-frame, shutters, pilasters, and the difterent parts 
 are explained in the figures. . 
 
 No. 3. a thickness of the pilaster or architrave ; b the rounded edge of 
 the boxing-stile ; c the breadth of the shutter ; d bead of the sash-frame ; 
 e under sash ; f top ditto ; g parting bead ; h outside lining and bead, 
 t the breadth of* the reveal or outer brick-work ; k k lintels made of strong 
 yellow deal or oak ; I the head of the ground ; m the architrave or pilaster 
 fixed upon the grounds ; n the soffit, tougued into the top of the sash- 
 frame-head ; and, on the other edge, into the head of the architrave m ; 
 0 the sash-frame head ; /? the elbow q capping ; r sash-frame cill ; s sash- 
 cill ; t stone-cill. 
 
 The face of the pulley-stile of every sash-frame ought to 
 project about three-eighths of an inch beyond the edge of 
 the brick- work; that is, the distance between the face of each 
 pulley- stile ought to be less by three quarters of an inch 
 than in the clear of the reveals on the outside ; so that the 
 face of the shutters ought to be in the same plane with the 
 stone or brick-work on the outside. 
 
 Fig. 616 shows a plan of a sash-frame and shutter on the same princi- 
 ple as the foregoing, and which may be applied to a similar window. 
 
 As the thickness of the wall is here conceived to be less thfin in the fore- 
 going example, another back-flap is introduced : — a the outside lining ; 
 b the pulley-stile ; c the inside lining ; d the back lining ; e fiha weights ; 
 g parting slip of weights ; h parting bead to sashes ; i inside bead ; k 
 back lining of boxing ; t ground, or boxing-stile, grooved to receive the 
 plastering ; m front shutter hung to the inside lining, c, of the sash- 
 frame by the hinge n ; o p back flaps hinged together at and to the 
 shutter at r; s architrave or pilaster. 
 
 Fig. 617. Is a vertical section of the cill, &c. of the same sash-frame , 
 a bottom rail of sash ; b cill of the sash-frame ; c back of recess of win- 
 dow ; d coping bead, or capping let into the sash-frame cill ; e inside 
 bead, tongued on the top of the cill ; h outside lining ;f space for the top-* 
 sash to run in ; g parting bead, 
 
 STAIRS. 
 
 This is one of the most important subjects connect- 
 ed with a joiner’s art, and should be attentively consi- 
 dered, not only with regard to the situation, but as to the 
 design and execution. The convenience of the building 
 depends on the situation ; and the elegance, on the design 
 and execution of the workmanship. In contriving a grand 
 edifice, particular attention must be paid to the situation of 
 the space occupied by the stairs, so as to give thein the 
 most easy command of the rooms. 
 
 With regard to the lighting of a good staircase, a sky- 
 light, or rather lantern, is the most appropriate ; for these 
 
 2q 
 
594 
 
 THE OPERATIVE MECHANIC 
 
 unite elegance with utility, that is, admit a powerful light, 
 with elegance in the design ; indeed, where the staircase 
 docs not adjoin the exterior walls, this is the only light that 
 can be admitted. Where the height of a stoiy is consider- 
 able, resting places are necessary, which go under the name 
 of quarter-paces, and half -paces, according as the passenger 
 has to pass one or two right-angles ; that is, as he has to 
 describe a quadrant or semi-circle. In very high stories, 
 which admit of sufficient head-room, and where the space 
 allowed for the staircase is confined, the staircase may 
 have two revolutions in the height of one story, which will 
 lessen the height of the steps ; but in grand staircases only 
 one revolution can be admitted, the length and breadth of 
 the space on the plan being always proportioned to the 
 heigh,t of the building, so as to admit of fixed proportions. 
 
 The breadth of the steps ought never to be more than 15 
 inches, or less than nine ; the height not more than seven, 
 or less than five : there are cases, however, wdiich are ex- 
 ceptions to all rule. When the height of the story is given 
 in feet, and the height of the step in inches, you may throw 
 the feet into inches, and divide it by the number of inches 
 the step is high, and the quotient will give the number of 
 steps. 
 
 It is a general maxim, that the greater breadth of a step 
 requires less height than one of less breadth : thus, a step 
 of 12 inches in breadth will require a rise of 5^ inches, which 
 may be taken as a standard, to regulate those of other di- 
 mensions. 
 
 Though it is desirable to have some criterion as a guide in 
 the arrangement of a design, yet workmen will, of course, 
 vaiy them as circumstances may require. Stairs are con- 
 structed variously, according to the situation and destina- 
 tion of the building. 
 
 Geometrical stairs are those which arc supported by 
 having one end fixed in the wall, and every step in the as- 
 cent having an auxiliary support from that immediately be- 
 low it, and the lowest step from the floor. 
 
 Bracket- stairs are those which have an opening or well, 
 with strings and newels, and are supported by landings and 
 carriages ; the brackets are mitred to the ends of each riser, 
 and are fixed to the string-board, which is moulded below 
 like an architrave. 
 
 Dog-lcgged stairs arc those which have no opening, or 
 well-hole, and have the rail and balusters of both the pro- 
 gressive and returning flights falling in the same vertical 
 
AND MACHINIST. 
 
 595 
 
 planes, the steps being fixed to strings, newels, and car- 
 riages, and the ends of the steps of the inferior kind termi- 
 nating only upon the side of the string, without any housing. 
 In taking dimensions and laying down the plan and section 
 of stair-cases, take a rod, and, having ascertained the num- 
 ber of steps, mark the height of the story, by standing the 
 rod on the lower floor : divide the rod into as many equal 
 parts as there are to be risers, then, if you have a level sur- 
 face to work upon below the stair, try each of the risers 
 as you go on, and this will prevent any excess or defect ; for 
 any error, however small, when multiplied, becomes of con- 
 siderable magnitude, and even the difference of an inch in 
 the last riser, will not only have a bad effect to the eye, but 
 will be apt to confuse persons not thinking of any such ir- 
 regularity. In order to try the steps properly by the story 
 rod, if you have not a level surface to work from, the better 
 way will be, to lay two rods on boards, and level their top 
 surface to that of the floor : place one of these rods a little 
 within the string, and the other near or close to the wall, so 
 as to be at right angles to the starting line of the first riser, 
 or, which is the same thing, parallel to the plan of the string ; 
 set off the breadth of the steps upon these rods, and num- 
 ber the risers ; you may set not only the breadth of the 
 flyers, but that of the winders also. In order to tiy the 
 story-rod exactly to its vertical situation, mark the same 
 distances of the risers upon the top edges, as the distances of 
 the plan of string-board, and the rods are from each other. 
 
 In bracket-stairs, as the internal angle of the steps is open 
 to the end, and not closed by the string as in common dog- 
 legged stairs, and the neatness of workmanship is as much 
 regarded as in geometrical stairs, the balusters must be 
 neatly dove-tailed into the ends of the steps, two in every 
 step. The face of each front baluster must be in a straight 
 surface with the face of the riser, and, as all the balusters 
 must be equally divided, the face of the middle baluster 
 must stand in the middle of the face of the riser of the pre- 
 ceding step and succeeding one. The risers and heads are 
 all previously blocked and glued together, and when put up, 
 the under side of the step nailed or screwed into the under 
 edge of the riser, and then rough brackets to the rough 
 strings, as in dog-legged stairs, the pitching pieces and 
 rough strings being similar. In glueing up the steps, the 
 best method is to make a templet, so as to fit the external 
 angle of the steps with the nosing. 
 
 2 q2 
 
59G 
 
 THE OFERATIVF. MECHANIC 
 
 The steps of geometrical stairs ought to be constructed so 
 as to have a very light and clean appearance when put up : 
 for this purpose, and to aid the principle of strength, the 
 risers and treads, when planed up, ought not to be less than 
 one eighth of an inch, supposing the going of the stair, 
 or length of the step, to be four feet, and for every six inches 
 in length, another one-eighth may be added. The risers 
 ought to be dove-tailed into the cover, and when the steps 
 are put up, the treads are screwed up from below to the 
 under edge of the risers. The holes for sinking the heads of 
 the screws ought to be bored with a centre-bit, then fitted 
 closely in with wood, well matched, so as entirely to con- 
 ceal the screws, and appear as one uniform surface. Brack- 
 ets are mitred to the riser, and the nosings are continued 
 round. In this mode, however, there is an apparent de- 
 fect ; for the brackets instead of giving support, are them- 
 selves unsupported, and dependent on the steps, being of no 
 other use, in point of strength, than merely tying the risers 
 and treads of the internal angles of the steps together : and, 
 from the internal angles being hollow, or a re-entrant angle, 
 except at the ends, which terminate by the wall at one extre- 
 mity, and by the brackets at the other, there is a want of 
 regular finish. Tlie cavetto, or hollow, is carried round the 
 front of the riser, and is returned at the end, and mitred 
 round the bracket, and if an open string, that is, the under 
 side of the stairs open to view, the hollow is continued along 
 the angle of step and riser. 
 
 The best plan, however, of constructing geometrical stairs 
 is, to put up the strings, and to mitre the brackets to the 
 risers, as usual, and enclose the soffit with lath and plasteiv 
 which will form an inclined plane under each flight, and a 
 winding surface under the winders. In superior staircases, 
 for the best buildings, the soffit may be divided into panels. 
 If the risers are made from two inch planks, it will greatly 
 add to the solidity. The method of drawing and executing 
 the scroll, and other wreath parts of the hand-rail, will be 
 given in a subsequent part of this article. 
 
 In constructing a flight of geometrical stairs, where the 
 soffit is inclosed as above, the bearers should all be framed 
 together, so that when put up, they will form a perfect 
 staircase. Each piece of frame-work, which forms a riser, 
 should, in the partition, be well wedged at the ends, lliis 
 plan is always advisable when strength and firmness are re- 
 quisite, as the steps and risers are entirely dependent on the 
 
AND MACHINIST. 597 
 
 framed carriages, wliich, if carefully put together, will never 
 yield to the greatest weight. 
 
 Fig-. 619 will show the section of this framing firmly put together, and 
 wedged into the partition, as above described. 
 
 In preparing the string for the wreath part, a cylinder 
 should be made of the size of the well-hole of the stair- 
 case, which can be done at a trifling expense ; then set the 
 last tread and riser of the flyers on one side, and the first 
 tread and riser of the returning flight on the opposite side, 
 at their respective heights ; then on the centre of the curved 
 surface of this cylinder, mark the middle between the two, 
 and with a thin slip of wood, bent round with the ruling 
 edge, cutting the two nosings of these flyers and passing 
 through the intermediate height marked on the cylinder, 
 draw a line, which will give the wreath line formed by 
 the nosings of the winders ; then draw the whole of 
 the winders on this line, by dividing it into as many parts 
 as you want risers, and each point of division is the nosing 
 of such winder. Having thus far proceeded, and carefully 
 examined your heights and widths, so that no error may 
 have occurred, prepare a veneer of the width intended 
 for your string, and the length given by the cylinder, and 
 after laying it in its place on the cylinder, proceed to glue a 
 number of blocks about an inch wide on the back of the 
 veneer, with their fibres parallel to the axis of the .cylinder. 
 When diy, this will form the string for the wreath part of 
 the staircase, to be framed into the straight strings. It is 
 here necessary to observe, that about five or six inches of 
 the straight string should be in the same piece as the circu- 
 lar, so that the joints fall about the middle of the first and 
 last flyers. This precaution always avoids a cripple, to 
 which the work would otherwise be subject. 
 
 Fig-. 6 IS, No. 1, is a plan of a dog-legged staircase, a the seats of the 
 newels, c the seat of the upper newel. 
 
 No. 2.** The elevation of the same. i 
 
 AB. The newels ; the part AC being turned. — DE the upper newel. — 
 FG the carriage piece. — HI upper string board framed into the newel. — 
 K a joist framed into the trimmer. 
 
 To describe the ramps ; produce the horizontal part of the knee to L, 
 and also the under side of the rail until it meets the face of the first balus- 
 ter, at c, make c d equal to c D, and upon A rf, and from the point d, draw 
 the perpendicular d L, and L is the centre for describing the ramps d D. 
 
 The story-rod ah'v&K very necessary article infixing the steps ; for, if 
 a common rule be used for this purpose, the workmen will be very liable 
 to err and render the stairs extremely faulty, -which cannot take place if the 
 story-rod be applied to every riser, and the successive risers be regulated 
 by it. 
 
598 
 
 THE OPERATIVE MECHANIC 
 
 In the construction of dog- legged staircases, the first 
 thing is, to take the dimensions of the stair, and the height 
 of the story, and lay down a plan and section upon a floor 
 to the full size, representing all the newels and steps ; then 
 the situation of the carriages, pitching pieces, long and cross 
 bearers, as also the string boards ; the strings, rails, and 
 newels, being framed together, must be fixed with temporary 
 supports. The string-board will show the situation of the 
 pitching-pieces, which must be put up in order, wedging 
 one end firmly into the wall, and fixing the other to the 
 string-board ; this being done, pitch up the rough strings, 
 and finish the carriage part of the flyers. Having proceeded 
 thus far, the steps are next applied, beginning at the bot- 
 tom and working upwards, the risers being all firmly nailed 
 into the treads. 
 
 In the best kind of dog-legged stairs, the nosings are re- 
 turned ; sometimes the risers are mitred to the brackets, and 
 sometimes mitred with quaker strings. In the latter case a 
 hollow is mitred round the internal angle of the under side 
 of the tread, and the face of the riser. Sometimes the 
 string is framed into the newel, and notched to receive the 
 ends of the steps ; the other end having a corresponding 
 notch-board, and the whole flight being put up like a step- 
 ladder. 
 
 Fig. 619, No. 1 and 2, is a plan and elevation of a geometrical stair- 
 case. The lower part, No. 2, shows the section of the steps and car- 
 riages, which are framed together as directed in a former part of this 
 article. 
 
 The methods of finding the different moulds necessary in 
 the formation of the wreath part of the hand-rail, will be 
 found in the next plate. 
 
 To draw the scroll oj a hand-raiL 
 
 Fig. 620. First make a circle inches in diameter, divide the diameter 
 into three equal parts, make a square in the centre of the circle equal to 
 one of those parts, and divide each side of the square into six equal parts. 
 
 Fig. 4, shows this square on a larger scale, and laid in the same position 
 as the little square above, with the different centres marked. The centre 
 at 1 draws from a to A, the centre at 2 from h to c, and the centre at 3 
 from c to dy &c. which mil complete the outside revolution at A : set the 
 thickness of the rail from cf and to x, draw the inside the reverse way, 
 and the scroll will be completed. 
 
 To draw the curtail- steps. 
 
 Set the balusters in their proper places on each quarter of the scroll, 
 Fig. 3, the first baluster showing the return of the nosing round the 
 step, the second placed at the beginning of the twist, and the third a 
 quarter distant, and straight with the front of the last riser ; then set the 
 projection of the nosing without, and draw it round equally distant from 
 the scroll, which will give the form of the curtail. 
 

 Frayn 618 to 6‘J2 
 
 n.87 
 
AND MACHINIST. 
 
 599 ^ 
 
 As the method of getting a scroll out of a solid piece of 
 wood, having the grain of the wood to run in the same 
 direction with the rail, is far preferable to any other method 
 with joints, being much stronger and more beautiful than 
 any other scroll with one or two joints, we shall here give the 
 method of finding a face- mould to apply on the face of the 
 plank. 
 
 Place your pitch board I m n with m n passiag" throus^h the eye of tlie 
 scroll, then draw ordinates across the scroll at discretion, and take the 
 leng-th of the line o n, with its divisions, and lay it on o «, at Fig’. 621, then 
 the ordinate being drawn, take the different distances 2 x, 8 4 v. See. 
 
 and transfer them to 2 y, 3 2 ;, 4 v, Sec. and the rest of the points being taken 
 in the same manner, a curve may be traced which will be the face-mould 
 required. 
 
 To find the parallel thickness of the plank. 
 
 Fig. 622. Let Imn he the pitch board, and let the level of the scroll 
 rise one-sixth, that is, divide I m into six equal parts, and the bottom 
 division is the top of the level of the scroll ; from the end of the pitch 
 board, set on n to 0 , half the thickness of abaluster, t(> the inside ; then set, 
 from 0 to p, half the width of the rail, and draw the form of the rail on 
 the end at y, the point n being where the front of the riser comes, the 
 point jo will be the projection of the rail before it : draw a dotted line to 
 touch the nose of the scroll, parallel with I n, then the distance between 
 this dotted line and the under tip of the scroll, will show the exact thick- 
 ness of planking ; but there is no occasion for the thickness to come quite 
 to the under side, for if it come to the under side of the hollow' it will be 
 sufficient, as a little bit glued under the hollow could not be discernible, 
 and can be no hurt to the scroll. In ordinary cases, where the tread is 
 about 11 inches, and rise 6^, a scroll can be got out of a piece, about 4.^ 
 inches thick. 
 
 To describe a section of a hand-rail^ supposing it to be two 
 inches deep^ and two and a quarter inches broad^ the usual 
 dimensions. 
 
 Fig. 622. Let ABCD be a section of the rail, as squared ; on AB de- 
 scribe an equilateral triangle AB a ; from a, as a centre, describe an arc 
 to touch AB, and to meet a A and a B ; take the distance between the 
 point of section in a A and the point A, and transfer it fiom the point o. 
 section to k, upon the same line a A, join Dk ; from ky with the distance 
 between k and the end of the arc, describe another arc, to meetD k ; with 
 the same distance describe a third arc, of contrary curvature, and draw a 
 vertical line to touch it ; which will form one side of the section of the 
 rail, and the counter part may be formed by a similar operation. 
 
 The branch of Joinery that falls under our next and last 
 consideration is that of hand* railing ; which calls into action 
 all the ingenuity and skill of the workman. This art con- 
 sists in constructing hand-rails by moulds, according to the 
 geometrical principles, that if a cylinder be cut in any di- 
 *’ection, except parallel to the axis, or base, the section will 
 be an ellipsis ; if cut parallel to the axis, a rectangle ; and if 
 parallel to the base, a circle. 
 
TWB OPERATIVE MECHANIC 
 
 600 
 
 Now, suppose a hollow cylinder be made to the size of the 
 well-hole of the stair-case, the interior concave, and the ex- 
 terior convex ; and the cylinder be cut by any inclined or 
 oblique plane, the section formed will be bounded by two 
 concentric similar ellipses ; consequently, the section will 
 be at its greatest breadth at each extremity of the larger 
 axis, and its least breadth at each extremity of the smaller 
 axis. Therefore, in any quarter of the ellipsis there will be 
 a continued increase of breadth from the extremity of the 
 lesser axis to that of the greater. Now it is evident that a 
 cylinder can be cut by a plane through any three points ; 
 therefore, supposing we have the height of the rail at any 
 three points in the cylinder, and that we cut the cylinder 
 through these points, the section will be a figure equal and 
 similar to the face-mould of the rail ; and if the cylinder be 
 cut by another plane parallel to the section, at such a dis- 
 tance from it as to contain the thickness of the rail, this 
 portion of the cylinder will represent a part of the rail with 
 its vertical surfaces already worked : and, again, if the back 
 and lower surface of this cylindric portion be squared to 
 vertical lines, either on the convex or concave side, through 
 two certain parallel lines drawn by a thin piece of wood 
 which is bent on that side, the portion of the cylinder thus 
 formed, will represent the part of the rail intended to be 
 made. 
 
 Though the foregoing only relates to cylindrical well- 
 holes, it is equally applicable to rails erected on any seat 
 whatever. 
 
 face-mould applies to the two faces of the plank, and 
 is regulated by a line drawn on its edge, which line is ver- 
 tical when the plank is elevated to its intended position. 
 This is also called the raking-mould. 
 
 The falling-mould, is a parallel piece of thin wood ap- 
 plied and bent to the side of the rail-piece, for the purpose 
 of drawing the back and lower surface^ which should be so 
 formed, that every level straight line, directed to the axis of 
 the well-hole, from every point of the side of the rail formed 
 by the edges of the falling mould, coincide with the surface. 
 
 In order to cut the portion of rail required, out of the least 
 possible thickness of stuff, the plank is so turned up on one 
 of its angles, that the upper surface is no where at right 
 angles to a vertical plane passing through the chord of the 
 plane ; the plank in this position is said to be sprung 
 
 pitch-hoardi is a right-angled triangular board made 
 to the rise and tread of the step, one side forming the right 
 
AND MACHINIST. 
 
 601 
 
 angle of the width of the tread, and the other of the height 
 of the riser. When there are both winders and flyers, two 
 pitch- boards must be made to their respective treads, but, 
 of course, of the same height, as all the steps rise the same. 
 
 The bevel by which the edge of the plank is reduced 
 from the right angle when the plank is sprung, is termed 
 the spring of the plank, and the edge thus bevelled is called 
 the sprung edge. 
 
 The bevel by which the face mould is regulated to each 
 side of the plank, is called the pitch. 
 
 The formation of the upper and lower surfaces of a rail is 
 called the falling of the rail the upper surface of the rail 
 is termed the hack. 
 
 In the construction of hand-rails, it is necessary to spring 
 the plank, and then to cut away the superfluous wood, as 
 directed by the draughts, formed by the face-mould ; v^^hich 
 may be done by an experienced workman, so exactly, with 
 a saw, as to require no further reduction ; and when set in 
 its place, the surface on both sides will be vertical in all 
 parts, and in a surface perpendicular to the plan. In order 
 to form the back and lower surface, the falling mould is ap- 
 plied to one side, generally the convex, in such a manner, 
 that the upper edge of the falling mould at one end, coin- 
 cides with the face of the plank ; and the same in the 
 middle, and leaves so much wood to be taken away at the 
 other end as will not reduce the plank on the concave side ; 
 — the piece of wood to be thus formed into the wreath or 
 twist being agreeable to their given heights. 
 
 In the following figures, we have given the method o. 
 finding the moulds necessary for constructing a hand-rail on 
 a circular plan. 
 
 Fi^. 623, is the plan, showing part of the winders, which in this case 
 are eight, as also the seat of the joint. 
 
 Fig. 624. Let AAA, &c. be the outside, and a a a, &c. the inside of the 
 plan. BCD a line passing through the middle of the breadth, BC being 
 straight, and CD one-fourth of the circumference of the circle, the ])oint 
 K in the middle of the arc CD, B at one extremity of the line BCED, 
 and D at the other. 
 
 Divide the quadrant CD into any number of equal parts, which in this 
 example are four. DraAv the straight line MN, and make MN equal to 
 the developeraent of the quadrant AAA, &c. on the convex side. Draw 
 ^10 perpendicular to MN, and make MO equal to the height of a step ; 
 draw OP parallel to MN, and make OP equal in length to the width of a 
 step, and join PM. 
 
 Draw N s perpendicular to MN. In Ns make N o equal to the height 
 of four of the winders, and join o M* curve otf the angle at M, in the 
 manner shown below, by intersection of lines : Through o draw x y per- 
 pendicular to M 0 , make o x and oy each equal to half the width of the 
 felling mould, and draw the upper ami lower edges of the mould. 
 
THE OPERATIVE MECHANIC 
 
 GQ2 
 
 Join DE. Fig’. 624, and produce DE to F. Draw DG and EL. Make 
 DG equal to one-fourth (or any part of) the heig^ht from N to the upper 
 cdg-e of the falling’ mould, Fig’. 625, and EL equal to one-fourth, or the 
 saine part, of the heig-ht from Q to the upper ed^e of the falling- mould. 
 Join (jL and produce it to meet DE in F, join the dotted line BF. Draw 
 IK, through the centre F, perpendicular to BF. Draw ah^ ah, &c. meet- 
 ing IK. At any convenient distance from KI draw c d parallel to IK. 
 Make the perpendicular of the face-mould equal to its corresponding 
 height on the falling mould, and draw the straight line c e ; then draw 
 ordinates A b, A b, &c. continue them until they meet c e, and from the 
 points of intersection draw perpendiculars to c e, and set off the distances 
 as shown by corresponding letters. Then by tracing a curve through 
 these points the face mould will be completed. 
 
 The top line r r r, &c. is left on the falling mould, to regulate its posi- 
 tion when bent upon the convex surface, as the line r >• r, and will fall into 
 the plane surface of the top of the plank. This line is obtained by making 
 the perpendiculars fr, 2 r, f r, &c. equal to the corresponding perpeiu 
 dicularsy* b,fb, &c. Fig. 624. To find the face-mould of a staircase, so 
 that when set to its proper rake it will be perpendicular to the plan where- 
 on it stands for a level landing. 
 
 Fig. 626. Draw the central line, a b, parallel to the sides of the rail; 
 on the right line a b apply the pitch-board of a flyer, from b to c dra\i 
 ordinates n m, o p, qr, s t, uv, at discretion, observing to draw one from 
 the point r, so that you may obtain the same point exactly in the face- 
 mould ; then take the parts which the ordinates give on the line a b, and 
 apply them at Fig. 627, and take the distances m 7i, p o, &c. and transfer 
 them to Fig. 627, and a curve through these points will be the face-mould 
 required. 
 
 To find the fallmg mould. 
 
 Fig. 626. Divide the radius of the circle into four equal parts, and set 
 three of these parts from 4 to a; through x y, the extremities of t)ie 
 diameter of the rail, draw ax and ay, producing them till they touch 
 the tangent AB ; then will AB be the circumference of the semicircle 
 X by, which is applied from A to B, Fig. 628, as a base line. Make A a 
 the height of a step ; draw the hypotenuse a B, apply the pitch board 
 of a flyer at a & c, and B e, then curve off the angle by intersection of 
 lines, and draw a line parallel to it, for the upper edge or the mould. 
 
 MEASURES CUSTOMARY IN JOINERs’ WORK. 
 
 Prepared boarding is measured by the foot superficial ; 
 the following being the different distinctions : — edges shot ; 
 edge shot, ploughed, and torigued ; wrought on one side, 
 and edges shot ; wrought on both sides, and edges shot ; 
 wrought on both sides, ploughed, and tongucd ; boards 
 keyed and clamped, mortise-clamped, and mortise and 
 mitre-clamped. The prices are regulated according to the 
 thickness. If the boards be glued, an additional price per 
 foot is allowed ; if tongued, still more, according to the 
 description of tongue. In boarded flooring, the dimensions 
 are taken to the extreme parts, from which the squares arc 
 to be computed. Deductions for chimneys, stair-cascs 
 
jbuhlbiko 
 
 From 623 to 623 
 
 FIM 
 
 FTesU ^ sc 35 z StranJL 
 
AND MACHINIST. 
 
 (303 
 
 ^c. are taken from this. The price depends on the sur- 
 face, whether wrought or plain, the manner of the longi- 
 tudinal and heading-joints, the thickness of stuff, whether 
 the boards be laid one after the other, or folded, or whether 
 the floor be laid with boards, battens, or wainscot.- 
 
 Skirting, when wide, is also measured by the foot super- 
 ficial ; the price depending upon the position, whether level, 
 raking, or ramping, or upon the manner of finishing, whe- 
 ther plain, torus, or rebated, or scribed to the floor, or to the 
 steps, or upon the plan, w^hether straight or circular. 
 
 Weather-boarding, is measured by the square of 100 su- 
 perficial feet. 
 
 Boarded partitions are measured by the square, from 
 which must be deducted the doors and windows, except an 
 agreement be made to tlie contrary. 
 
 The price of all kinds of framing depends on the thick- 
 ness, or whether the framing be plainer moulded; and if 
 moulded, the description of moulding, whether struck on the 
 solid, or laid in, mitred, or scribed ; as also upon the num- 
 ber of panels in a given height and breadth, and upon the 
 nature of the plan. 
 
 The different kinds of wainscotting, as window linings, 
 door linings, back linings, partitions, doors, shutters, &c. 
 are all measured by the superficial foot. 
 
 Windows are in general valued by the foot superficial; 
 though sometimes by the window. When measured, the 
 dimensions are taken for height, from the top of the cill to 
 the under side of the head, allowing seven inches for the 
 head and cill ; and for width in clear of pulley- stiles, allow- 
 ing eight inches. The sash and frame are either measured 
 together or separately. 
 
 Skylights are measured by the foot superficial, their price 
 depending on the plan and elevation. Framed grounds at 
 per foot run. 
 
 Ledged doors by the foot superficial, dado by the super- 
 ficial foot ; the price depending whether the plan be straight 
 or circular, or the elevation level or inelined. 
 
 In measuring stair-cases, the risers, treads, and carriages, 
 are generally classed together, and measured by the foot su- 
 perficial : the price varying as the steps are flyers or wind- 
 ers, as the risers are mitred into the string-board, the treads 
 dove-tailed for balusters, and the nosings returned, or whe- 
 ther the bottom of the risers be tongued into the treads. The 
 curtail step is generally valued as a whole. Returned nosings 
 at so much each ; and if circular, double the price of straight 
 
604 
 
 THE OPERATIVE MECHANJQ 
 
 ones. The brackets at so much each, according to the pat- 
 tern, and whether straight or circular. 
 
 Hand-railing is measured by the foot run, the price de- 
 pending on the materials, the diameter of the well-hole, or 
 whether ramped, swan- necked, level, circular, or wreathed, 
 or whether made out of the solid, or in thicknesses. The 
 scroll is paid at per piece. The joints at so much each, and 
 three inches of the straight part at each end of the wreath 
 are included in the measurement. Deal balusters are pre- 
 pared and fixed at per piece ; as also iron balusters, iron 
 column to curtail, housings to steps, &c. An extra allowance 
 is made for the additional labour .in fixing the iron balusters. 
 
 The price of string-board is regulated by the foot super- 
 ficial, according to the manner in which it is moulded, whe- 
 ther straight, circular, or wreathed, and the manner in 
 which such string is backed. The shafts of columns are 
 measured by the foot superficial ; the price depending upon 
 the diameter, and whether it be straight or curved, or pro- 
 perly glued and blocked. If the column be fluted or reeded, 
 the flutes or reeds are measured by the foot run, their price 
 depending upon the size of the flute or reed The headings 
 of flutes and reeds are at so much each. Pilasters, straight 
 or curved, in the height, ai*e measured in the same way, and 
 the price taken per foot superficial in the caps and bases if 
 pilasters ; besides the mouldings, the mitres must be so 
 much each, according to the size. 
 
 Mouldings are valued by the foot run, as double-faced ar- 
 chitraves, base and surbase. The head of an architrave in 
 a circular wall, is four times the price of the perpendicular 
 parts, not only on account of the time required to form the 
 mouldings to the circular plan, but on account of the greater 
 difficulty of forming the mitres. 
 
 All horizontal mouldings, circular upon plan, are three or 
 four times the price of those on a straight plan ; being 
 charged more, as the radius of the circle is less : housings to 
 mouldings are valued at so much each, according to the size. 
 
 The price per superficial foot of mouldings is regulated by 
 the number of quirks, for each of which an addition is made 
 to the foot. 
 
 The price of mouldings depends also upon the materials 
 of which they are made, and upon their running figure, whe- 
 ther curved or raking. 
 
 In grooving, the stops arc paid over and above, and so 
 much more must be allowed for all grooves wrought by 
 hand, particularly in the parts adjoining the concourse of 
 
AND MACHINIST. 
 
 ms 
 
 ail angle : circular grooving must be paid still more. Water 
 trunks are measured by the foot run ; the rate depending 
 upon the side of their square : the hopper-heads and shoes 
 are valued at so much each, as also are the moulded weather 
 caps, and the joints. Scaffolding, &c. used in fixing, is 
 charged extra. 
 
 Flooring-boards are prepared, that is, planed, gauged, and 
 rebated to a thickness at so much each, the price depending 
 upon the length of each board ; if more than nine inches 
 broad, the rate is increased according to the additional 
 width ; each board listing at so much per list. 
 
 The following is a classification of such articles in joinery 
 as are usually rated at so much each. 
 
 Trusses. 
 
 Cantalivers. 
 
 Iliile-joints. 
 
 Cut brackets fur shelves. 
 
 Housing’s in g’encral. 
 
 Housinirs to steps. 
 
 Cutting’s to standarda. 
 
 Elbow capping’s. 
 
 Returned moulded nosings to steps. 
 Caps to hand-rails. 
 
 Scroll of hand-rails. 
 
 Making and fixing joists of hand- 
 rails with joint-screws. 
 
 Fixing iron coiunms in curtails. 
 Fixing iron baluster, and prepar- 
 ing mould. 
 
 Preparing and fixing deal balusters. 
 
 Articles at 'per foot 
 
 Sinking to shelves. 
 
 Moulded raisings of panels. 
 
 All raised panels in the extremity 
 of the raising to be charged ex- 
 tra. 
 
 Capping to wainscot. 
 
 Level circular string-boards to 
 stairs. 
 
 Hand-rails. 
 
 Newels to stairs. 
 
 Moulded planiers in stairs. 
 
 Sinking in rail for iron rail or ba- 
 lusters. 
 
 Water-trunks and spouts. 
 
 Skirting and door-grounds. 
 
 Beads or fillets. 
 
 Articles at per 
 
 Deals pinned, ploughed, tongued, 
 leacled, glued, and clamped. 
 
 Brackets to stairs. 
 
 Curtail step. 
 
 Clam})-initres. 
 
 Mitres of pilasters according to 
 their size. 
 
 Mitres of cornices. 
 
 Headings to flutes and reeds'. 
 Hopper-heads and shoes to water- 
 trunks. 
 
 Joints to water-trunks. 
 
 Preparing flooring-boards and bat- 
 tens. 
 
 Fixing locks and fastenings, per 
 article. 
 
 Hole in seat of water-closet. 
 Patteras, 
 
 'unningy or lineal. 
 
 Fillets mitred on panels. 
 
 Square or beaded angle -staff, re- 
 bated. 
 
 Mouldings. 
 
 Single cornice. 
 
 Single faced architrave. 
 
 Pilasters under four inches wide. 
 Boxings to windows. 
 
 Ornamental grooving. 
 
 Narrow linings. 
 
 Legs, rails, and runners of dres- 
 sers. 
 
 Border to hearth. 
 
 Base-moulding. 
 
 Surbase-rnoulding. 
 
 Narrow skirting. 
 
 foot superficiaL 
 
 Skirting. 
 
 Sash-frames and sashes. 
 
THE OPERATIVE MECHANIC 
 
 cm 
 
 8ky]i<^hts. 
 
 'Back, cibow, soffits, 
 
 Slmtters. 
 
 Framed or plain back-liniiig-s. 
 Door-lining's, jambs. 
 Wainscotting'. 
 
 Dado. 
 
 Partitions. 
 
 Siej)s and rises to stairs, incliidiii"’ 
 carriag-es. 
 
 Cradling. 
 
 Double-faced architraves. 
 Mouldings wrought by hand, if 
 large. 
 
 Shafts of columns. 
 
 PLASTERING. 
 
 The Plasterer is a workman to whom the decorative part 
 of architecture owes a considerable portion of its effect^ and 
 whose art is requisite in every kind of building. 
 
 The tools of the plasterer consist of a spade or shovel of 
 the usual description ; a rake, with two or three prongs, 
 bent downwards from the line of the handle, for mixing the 
 hair and mortar together; trowels of various kinds and 
 sizes ; stopping and picking-out tools; rules called straight- 
 edges ; and wood models. 
 
 The trowels used by plasterers are more neatly made than 
 tools of the same name used by other artificers. The lay- 
 ing and smoothing tool consists of a flat piece of hardened 
 iron, about ten inches in length, and two inches and a half 
 wide, very thin, and ground to a semicircular shape at one 
 end, but left square at the other; and at the back of the plate, 
 near the square end, is rivetted a small iron rod with two 
 legs, one of which is fixed to the plate, and the other to a 
 round wooden handle. With this tool all the first coats of 
 plaster is laid on, as are also the last, or, as it is technically 
 termed, the setting. The other kinds of trowels are made 
 of three or four sizes, for gauging the fine stuff and plaster, 
 used in forming cornices, mouldings, &c. The longest size 
 of these is about seven inches on the plate, which is of po- 
 lished steel, about two inches and three quarters broad at 
 the heel, diverging gradually to a point. To the heel or 
 broad end a handle is adapted. 
 
 The stopping and picking- out tools are made of polished 
 steel, of different sizes, though most generally about seven 
 or eight inches in length, and half an inch in breadth, flat- 
 tened at both ends, and ground somewhat round. These 
 tools are used in modelling and finishing mitres and re- 
 turns to cornices ; as likewise in filling- up and perfecting 
 the ornaments at the joinings. 
 
 The straight-edges are for keeping the work in an even, 
 or perpendicular line ; and the models or moulds are for run- 
 
AND MACHINIST. 
 
 607 
 
 iiing plain mouldings, cornices, &c.; of these latter the 
 plasterer requires a great number as very little of his finish- 
 ing can be done without them. 
 
 Experienced workmen keep their tools very clean, and 
 have them daily polished by the hawk-boys. 
 
 Plasterers have technical divisions of their work, by which 
 its quality is designated, and value ascertained ; as, lathing ; 
 laying ; pricking-up ; lathing, laying, and set ; lathing, float- 
 ing, and set; screed, set or putty; rendering and set, or 
 rendering, floated, and set ; trowelled stucco, &c. ; each of 
 which, hereafter, we shall very minutely explain. 
 
 In all the operations of plastering, lime extensively 
 abounds ; we shall, therefore, first offer some observations 
 on the properties of this important article. 
 
 Ail who have written on the subject of lime, as a cement, 
 have endeavoured to ascertain what is the due proportion 
 of sand for making the most perfect cement ; but with a 
 little attention it is evident, that ail prescribed rules must 
 be so very vague and uncertain, as to be of little utility to 
 the workman, for, besides the variation which is occasioned 
 by a more or less degree of calcination, it is a certain fact, 
 that some kinds of lime-stone are much more pure, and 
 contain a much smaller proportion of sand than others ; 
 consequently, it would be absurd to say, that pure lime 
 requires as small a proportion of sand, when made into 
 mortar, as that which originally contained in itself a large 
 proportion. 
 
 The variation thus produced, in regard to the proportion 
 of sand, is found to be extremely great. It is, however, 
 stated, that the best mortar which has come under exa- 
 mination, was formed of eleven parts of sand to one of 
 lime: to which was added, by measure, between twice and 
 thrice its own bulk of sand, whieh may be allowed to have 
 been at least three times its quantity by weight. Supposing, 
 therefore, that every particle of the lime had been so per- 
 fectly calcined as to be in a caustic state, there could not be 
 less than forty-seven parts of sand to one of lime ; but it 
 is hard to suppose, that above one hundredth part of this 
 mass, independent of the water, consisted of pure caustic 
 calcareous earth. 
 
 From these considerations it is conceived, that it is im- 
 possible to prescribe any determinate proportion of sand to 
 lime, as that must vary according to the nature of the lime, 
 and other incidental circumstances, which would form an 
 infinity of exceptions to any general rule. But it would 
 
608 THE OPERATIVE MECHANIC 
 
 seem, that it might be safely inferred, that the moderns in 
 general rather err in giving too little, than in giving too 
 much sand. It deserves, however, to be noticed, that the 
 sand, when naturally in the lime-stone, is more intimately 
 blended with the lime, than can possibly be ever effected by 
 any mechanical operation ; so that it would be in vain to 
 hope to make equally good mortar artificially from pure 
 lime, with so small a proportion of caustic calcareous mat- 
 ter, as may sometimes be effected when the lime naturally 
 contains a very large proportion of sand. Still, however, 
 there seems to be no doubt, that if a much larger propor- 
 tion of sand than is common were employed, and that more 
 carefully and expeditiously blended and worked, the mortar 
 would be made much more perfect, as has been proved by 
 actual experiments. 
 
 Another circumstance, which greatly tends to vary the 
 quality of cement, and to make a greater or smaller pro- 
 portion of sand necessary, is, the mode of preparing the 
 lime before it is beaten up into mortar. When for plaster, 
 it is of great importance to have every particle of the lime- 
 stone slaked before worked-up, for, as smoothness of sur- 
 face is the most material point, if any particles of lime be 
 beaten-up before sufficiently slaked, the water still continu- 
 ing to act on them, will cause them to expand, which will 
 produce those excrescences on the surface of the plaster, 
 termed blisters. Consequently, in order to obtain a perfect 
 kind of plaster, it is absolutely necessary that the lime, 
 before being worked, be allowed to remain a considerable 
 time macerating or souring in water : the same sort of pro- 
 cess, though not absolutely required, would considerably 
 improve the lime intended for mortar. Great care is re- 
 quired in the management ; the principal thing being the 
 procuring of well-burnt lime, and allowing no more lime, 
 before worked, than is just sufficient to macerate or sour it 
 with the water : the best burnt lime will require the ma- 
 ceration of some days. 
 
 It has been almost universally admitted, that the hardest 
 lime -stone affords the lime which will consolidate into the 
 firmest cement ; hence, it is generally concluded, that lime 
 made of chalk produces a much weaker cement than that 
 made of marble, or lime-stone. It would seem, however, 
 that, if ever this be the case, it is only incidentally, and not 
 necessarily. In the making of mortar, other substances are 
 occasionally mixed with lime, which we shall here proceed 
 to notice, and endeavour to point out their excellencies and 
 
AND MACHINIST 
 
 609 
 
 defects. Those commonly used, besides sand of various 
 denominations, are powdered sand-stone, brick-dust, and 
 sea-shells : and for forming plaster, where closeness rather 
 than hardness is required, lime which has been slaked and 
 kept in a dry place till it has become nearly effete, and 
 powdered chalk, or whiting, and gypsum, in various pro- 
 portions, besides hair and other materials of a similar nature. 
 Other ingredients have been more lately recommended, such 
 as earthy balls, slightly burnt and pounded, old mortar 
 rubbish, powdered and sifted, and various things of the 
 like kind, the whole of which are, in some respect or other, 
 objectionable. 
 
 Plaster of Paris is employed by the plasterer to give tht 
 requisite form and finish to all the superior parts of his work. 
 
 It is made of a fossile stone, called gypsum, which is ex- 
 cavated in several parts of the neighbourhood of Paris, 
 whence it derives its name, and is calcined to a powder, to 
 deprive it of its water of ciystallization. The best i? 
 Montmartre. 
 
 The stones are burnt in kilns, which are generally of vei7 
 simple construction, being not unfrequently built of the 
 gypsum itself. The pieces to be calcined are loosely put 
 together in a parallelepiped heap, below which are vaulted 
 pipes or flues, for the application of a moderate heat. 
 
 The calcination must not be carried to excess ; as other- 
 wise the plaster will not form a solid mass w^hen mixed with 
 a certain portion of water. During the process of calcina- 
 tion, the water of crystallization rises as white vapour, 
 which, if the atmosphere be dry, is quickly dissolved in air. 
 
 The pounding of the calcined fragments is performed 
 sometimes in mills constructed for the purpose, and some- 
 times by men, whose health is much impaired by the par- 
 ticles of dust settling upon their lungs. 
 
 On the river Wolga, in Russia, where the burning of gyp- 
 sum constitutes one of the chief occupations of the pea- 
 santry, all kinds of gypsum are burnt promiscuously on 
 grates made of wood ; afterwards the plaster is reduced to 
 powder, passed through a sieve, and finally formed into 
 small round cakes, which are sold at so much per thousand. 
 
 These balls are reduced into an impalpable powder by 
 the plasterer, and then mixed with mortar. The less the 
 gypsum is mixed with other substances, the better it is 
 qualified for the purpose of making casts, stucco, &c. The 
 sparry gypsum, or selenite, which is the purer kind, is em#- 
 ployed for taking impressions from coins and medals, and 
 
 2 R 
 
610 
 
 THE OPERATIVE MECHANIC 
 
 for making those beautiful imitations of marble, granite, 
 and porphyry, known by the name of scagliolcty which is 
 derived from the Italian word, scagli. 
 
 Finely powdered alabaster, or plaster of Paris, when 
 heated in a crucible, assumes the appearance of a fluid, by 
 rolling in waves, yielding to the touch, steaming, &c. all of 
 which properties it again loses on the departure of the 
 heat : if taken from the crucible and thrown upon paper, it 
 will not wet it ; but immediately be as motionless as it was 
 before exposed to the heat. 
 
 Two or three spoonfuls of burnt alabaster mixed up thin 
 with water, will, at the bottom of a vessel filled with water, 
 coagulate into a hard lump, notwithstanding the water 
 that surrounds it. The coagulating or setting property 
 of burnt alabaster will be very much impaired, or lost, 
 if the powder be kept for any considerable time, and 
 more especially in the open air. When it has been once 
 tempered with water, and suffered to grow hard, it cannot 
 be rendered of any further use. 
 
 Plaster of Paris, diluted with water into the consistence of 
 a soft or thin paste, quickly sets, or grows firm, and at the 
 instant of its setting, has its buik increased. This expansive 
 property, in passing from a soft to a firm state, is one of its 
 valuable properties ; rendering it an excellent matter for 
 filling cavities in sundry works, w^here other earthy mix- 
 tures would shrink and leave vacuities, or entirely separate 
 from the adjoining parts. It is also probable that this ex- 
 pansion of the plaster might be made to contribute to the 
 elegance of the impressions it receives from medals, &c. by 
 properly confining it when soft, so that, at its expansion, it 
 would be forced into the minutest traces of the figures. 
 
 A plaster of a coarser description, made of a blueish 
 stone, much like that of which Dutch terras are made, 
 is sometimes used in this country, for floors in gentlemen's 
 houses, and for corn-granaries. This stone, when burnt 
 after the manner of lime, assumes a white appearance, but 
 does not ferment on being mixed with water : when cold, it 
 is reduced to a fine powder. About a bushel of this powder 
 is put into a tub, and water is applied till it becomes liquid. 
 In this state it is well stirred with a stick, and used im- 
 mediately ; for in less than a quarter of an hour it becomes 
 hard and useless, as it will not allow of being mixed a 
 second time. 
 
 Other cements are used by plasterers for inside work. 
 The first is called lime and haivy or coarse stuffy and is pre- 
 
AND MACHINIST. 
 
 611 
 
 pared as common mortar, with the addition of hair from 
 the tan-yards. The mortar is first mixed with a requisite 
 quantity of sand, and the hair is afterwards worked in by 
 the application of a rake. 
 
 Next to this is Jine which is merely pure lime, 
 
 slaked first with a small quantity of water, and afterwards, 
 without any extraneous addition, supersaturated with w^ater, 
 and put into a tub in a half fluid state, where it is allowed to 
 remain till the water is evaporated. In some particular cases, 
 a small portion of hair is incorporated. When this fine 
 stuff is used for inside walls, it is mixed with very fine 
 washed sand, in the proportion of one part sand to three 
 parts of fine stuff, and is then called trowelled or bastard 
 stucco, with which all walls intended to be painted are 
 finished. 
 
 The cement called gauge stuff', consists of three-fifths of 
 fine stuff, and one-fifth plaster of Paris, mixed together with 
 water, in small quantities at a time, to render it more ready 
 to set. This composition is mostly used in forming cor- 
 nices and mouldings run with a wooden mould. When 
 great expedition is required, plasterers gauge all their mor- 
 tars with plaster of Paris, which sets immediately. 
 
 The technical divisions of plasterer's work shall now claim 
 our attention. 
 
 Lathing, the first operation, consists in nailing laths on the 
 ceiling, or partition. If the laths be of oak, they will require 
 wrought iron nails ; but if of deal, nails made of cast iron 
 may be used. Those mostly used in London are of fir, im- 
 ported from America and the Baltic, in pieces called staves. 
 Laths are made in three foot and four foot lengths : and 
 with respect to their thickness and strength, arc either sin- 
 gle, lath and half, or double. The single are the thinnest 
 and cheapest ; those called lath and half, are supposed to be 
 one third thicker than the single ; and the double laths are 
 twice that thickness. In lathing ceilings, the plasterer 
 should use both the lengths alluded to, and in nailing them 
 up, should so dispose them, that the joints be as much 
 broken as possible, that they may have the stronger key or 
 tie, and thereby strengthen the plastering with which they 
 are to be covered. The thinnest laths are used in partitions, 
 and the strongest for ceilings. 
 
 Laths are also distinguished into heart and sap laths : the 
 former should always be used in plain tiling ; the latter, 
 which are of inferior quality, are most frequently used by 
 the plasterer. 
 
 2 r2 
 
612 
 
 THE OPERATIVE MECHANIC 
 
 Laths should be as evenly split as possible. Those that 
 are very crooked should not be nsed^ or the crooked part 
 should be cut out ; and such as have a short concavity or. 
 the one side, and a convexity on the other, not very pro- 
 minent, should be placed with the concave sides outwards. 
 
 The following is the method of rending or splitting laths. 
 The lath-cleavers having cut their timber into the required 
 lengths, cleave each piece with wedges, into eight, twelve, 
 or sixteen pieces, according to the scantling of the timber, 
 called bolts ; and then, with dowl-axes, in the direction of 
 the felt-grain, termed felting, into sizes for the breadth of 
 the laths ; and, lastly, with the chit, clear them into thick- 
 nesses by the quarter grain. 
 
 Having nailed the laths in their appropriate order, the 
 plasterer’s next business is to cover theiri with plaster, 
 the most simple and common operation of which, is laq- 
 iug ; that is, spreading a single coat of lime and hair over 
 the whole ceiling, or partition ; carefully observing to keep 
 it smooth and even in every direction. This is the cheapest 
 kind of plastering. 
 
 PricJcing wp is performed in the same manner as the fore- 
 going ; but is only a preliminary to a more perfect kind 
 of work. After the plaster is laid on, it is crossed all over 
 with the end of a lath, to give it a tie or key to the coat 
 which is afterwards to be laid upon it. 
 
 Lathing, laying, and set, or what is termed lath and plas- 
 ter, one coat and set, is, when the work, after being lathed, 
 is covered with one coat of lime and hair, and afterwards, 
 when sufficiently dry, a thin and smooth coat spread over it, 
 consisting of lime only, or, as the workmen call it, putty, 
 or set. This coat is spread with a smoothing- trowel, used 
 by the workman with his right hand, while his left hand 
 moves a large flat brush of hog’s bristles, dipped in water, 
 backwards and forwards over it, and thus produces a sur- 
 face tolerably even for cheap work. 
 
 Lathing, floating, and set, or lath and plaster, one coat, 
 floated ami set, differs from the foregoing, in having the first 
 coat pricked up to receive the set, which is here called the 
 floating. In doing this, the plasterer is provided with a 
 substantial straight edge, frequently from ten to twelve feet 
 in length, which must be used by two workmen. All the 
 parts to be floated are tried by a plumb-line, to ascertain 
 whether they be perfectly flat and level, and whenever any 
 deficiency appears, the hollow is filled uj) with a trowel full 
 or more of lime and hair only, which is imncdifllling out, 
 
^AND MACIIINI.ST. 
 
 613 
 
 and when these preliminaries are settled, the screeds are next 
 formed. The term screed signifies a style of lime and hair, about 
 seven or eight inches in width, gauged quite true, by draw- 
 ing the straight edge over it until it be so. These screeds 
 are made at the distance of about three or four feet from 
 each other, in a vertical direction, all round the partitions 
 and walls of a room. When all are formed, the intervals 
 are filled up with lime and hair, called by the workmen, 
 stuff'^ till flush with the face of the screeds. The straight 
 edge is then worked horizontally on the screeds, by w’hich 
 all the superfluous stuff, projecting beyond them in the in- 
 tervals is removed, and a plain surface produced. This 
 operation is termed floating, and may be applied to ceilings 
 as well as to partitions, or upright walls, by first forming 
 the screeds in the direction of the breadth of the apartment, 
 and filling up the intervals as above described. As great 
 care is requisite to render the plaster sound and even, none 
 but skilful workmen should be employed. 
 
 The set to floated-work is performed in a mode similar to 
 that already prescribed for Laying; but being employed 
 only for best rooms, is done with more care. About one- 
 sixth of plaster of Paris is added to it, to make it set more 
 expeditiously, to give it a closer and more compact ap- 
 pearance, and to render it more firm and better calculated 
 to receive the white- wash or colour when dry. For floated 
 stucco-work the pricking up coat cannot be too dry ; but, if 
 the floating which is to receive the setting coat be too dry, 
 before the set is laid on, there will be danger of its peeling 
 off, or of assuming the appearance of little cracks, or shells, 
 which would disfigure the work. Particular care and at- 
 tention therefore must be paid to have the under coats in a 
 proper state of dryness. It may here be observed, that 
 cracks, and other unpleasant appearances in ceilings, are 
 more frequently the effect of weak laths being covered with 
 too much plaster, or too little plaster upon strong laths, 
 rather than of any sagging or other inadequacy in the tim- 
 bers, or the building. If the laths be properly attended to, 
 and the plaster laid on by a careful and judicious workman, 
 no cracks or other blemishes are likely to appear. 
 
 The next operation combines both the foregoing pro- 
 cesses, but requires no lathing ; it is called rendering and set, 
 or rendering, floated, and set. What is understood by 
 rendering, is the covering of a brick or stone wall with a 
 coat of lime and hair, and by set is denoted a superficial 
 goat of fine stuff or putty upon the rendering. These ope-t 
 
THE OPERATIVE MECHANIC 
 
 614 
 
 rations are similar to those described for setting of ceilings 
 and partitions ; and the floated and set is laid on the ren- 
 dering in the same manner as on the partitions, &c. already 
 explained, for the best kind of work. 
 
 Trowelled stucco, which is a very neat kind of work, nsea 
 in dining-rooms, halls, &c. where the walls are prepared to 
 be painted, must be worked upon a floated ground, and the 
 floating be quite dry before the stucco is applied. In this 
 process the plasterer is provided with a wooden tool, called 
 a float, consisting of a piece of half inch deal, about nine 
 inches long and three wide, planed smooth, with its lower 
 edges a little rounded off, and having a handle on the upper 
 surface. The stucco is prepared as above described, and 
 afterwards well beaten and tempered with clear water. 
 The ground intended to be stuccoed is first prepared with 
 the large trowel, and is made as smooth and level as pos- 
 sible; when the stucco has been spread upon it to the extent 
 of four or five feet square, the workman, with a float in his 
 right hand and a brush in his left, sprinkles with water, and 
 rubs alternately the face of the stucco, till the whole is re- 
 duced to a fine even surface. He then prepares another 
 square of the ground, and proceeds as before, till the whole 
 is completed. The water has the effect of hardening the 
 face of the stucco. When the floating is well performed, it 
 will feel as smooth as glass. 
 
 Rough casting, or rough walling, is an exterior finishing, 
 much cheaper than stucco, and, therefore, more frequently 
 employed on cottages, farm-houses, &c. than on buildings 
 of a higher class. The wall intended to be rough-cast, is 
 first pricked-up with a coat of lime and hair ; and when 
 this is tolerably dry, a second coat is laid on, of the same 
 materials as the first, as smooth as it can possibly be spread. 
 As fast as the workman finishes this surface, he is followed 
 by another with a pail-full of rough-cast, with which he 
 bespatters the new plastering, and the whole dries together. 
 The rough-cast is composed of fine gravel, washed from all 
 earthy particles, and mixed with pure lime and water till 
 the whole is of a semi-fluid consistency. This is thrown 
 from the pail upon the wall with a wooden float, about five 
 or six inches long, and as many wide, made of half-inch 
 deal, and fitted with a round deal handle. While, with this 
 tool, the plasterer throws on the rough-cast with his right 
 hand, he holds in his left a common whitewashers’ brush, 
 dipped in the rough-cast also, with which he brushes and 
 colours the mortar and the rough-cast he has already spread, 
 
AND MACHINIST. 615 
 
 to give them, when finished, a regular uniform colour and 
 appearance. 
 
 Cornices^ are either plain or ornamented, and sometimes 
 embrace a portion of both classes. The first point to be 
 attended to is, to examine the drawings, and measure the 
 projections of the principal members, which, if projecting 
 more than seven or eight inches, must be bracketted. This 
 consists in fixing up pieces of wood, at the distance of about 
 ten or twelve inches from each other, all round the place 
 proposed for the cornice, and nailing laths to them, covering 
 the whole with a coat of plaster. In the brackets, the stuff 
 necessary to form the cornices must be allowed, which in 
 general is about one inch and a quarter. A beech mould is 
 next made by the carpenter, of the profile of the intended 
 cornice, about a quarter of an inch in thickness, with the 
 quirks, or small sinkings, of brass or copper. All the sharp 
 edges are carefully removed by the plasterer, who opens 
 with his knife all the points whieh he finds incompetent to 
 receive the plaster freely. 
 
 These preliminaries being adjusted, two workmen, pro- 
 vided with a tub of putty and a quantity of plaster of Paris, 
 proceed to run the cornice. Before using the mould, they 
 gauge a screed of putty and plaster upon the wall and ceil- 
 ing, covering so much of each as wWl correspond with the 
 top and bottom of the intended cornice. On this screed 
 one or two slight deal straight-edges, adapted to as many 
 notches or chases made in the mould for it to work upon, 
 are nailed. The putty is then mixed with about one-third 
 of plaster of Paris, and brought to a semi-fluid state by the 
 addition of clean water. One of the workmen, with two or 
 three trowels-full of this composition upon his hmvk, which 
 he holds in his left hand, begins to plaster over the surface 
 intended for the cornice, with his trowel, while his partner 
 applies the mould to ascertain when more or less is wanted. 
 When a sufficient quantity of plaster is laid on, the workmen 
 holds his mould firmly against both the ceiling and the wall, and 
 moves it backwards and forwards, which removes the super- 
 fluous stuff, and leaves an exact impression of the mould 
 upon the plaster. This is not effected at once; for while he 
 works the mould backwards and forwards, the other work- 
 man takes notice of any deficiences, and fills them up by 
 adding fresh supplies of plaster. In this manner a cornice 
 from ten to twelve feet in length may be formed in a very 
 short time ; indeed, expedition is essentially requisite, as the 
 plaster of Paris occasions a very great tendency in the putty 
 
616 THE OPERATIVE MECHANIC' 
 
 to set, to prevent which, it is necessary to sprinkle the com- 
 position frequently with water, as plasterers, in order to 
 secure the truth and correctness of the cornice, generally 
 endeavour to finish all the lengths, or pieces, between any 
 two breaks or projections, at one time. In cornices which 
 have very large proportions, and in cases where any of the 
 orders of architecture are to be introduced, three or four 
 moulds are required, and are similarly applied, till all the 
 parts are formed. Internal and external mitres, and small 
 returns, or breaks, are afterwards modelled and filled up by 
 hand. 
 
 Cornices to be enriched with ornaments, have certain in- 
 dentations, or sinkings, left in the mould in which the casts 
 are laid. These ornaments were formerly made by hand ; 
 but now are cast in plaster of Paris, from clay models. 
 When the clay model is finished, and has, by exposure to 
 the action of the atmosphere, acquired some degree of firm- 
 ness, it is let into a wooden frame, and when it has been 
 retouched and finished, the frame is filled with melted wax, 
 wdiich, w'hen cold, is, by turning the frame upside down, 
 allowed to fall off, being an exact cameo, or counterpart, of 
 the model. By these means, the most enriched and curi- 
 ously wrought mouldings may be cast by the common plas- 
 terer. These wax models are contrived to cast about a foot 
 in length of the ornament at once ; such lengths being most 
 easily got out from the cameo. The casts are made of the 
 finest and purest plaster of Paris, saturated with water ; and 
 the wax mould is oiled previously to its being put in. When 
 the casts, or intaglios, are first taken from the mould, they 
 are not very firm ; but being suffered to dry a little, either 
 in the open air or an oven, they acquire sufficient hardness 
 to allow of being scraped and cleaned. 
 
 Basso-relievos and friezes are executed in a similar man- 
 ner, only the wax mould is so made, that the cast can have 
 a back-ground at least half an inch thick of plaster-cast to 
 the ornament or figure, in order to strengthen and secure 
 the proportions, at the same time that it promotes the ge- 
 neral effect. 
 
 The process for capitals to columns is also the same, ex- 
 cept that numerous moulds are required to complete them. 
 In the Corinthian capital a shaft or belt is first made, on 
 which is afterwards fixed the foliage and volutes; the whole 
 of which require distinct cameos. 
 
 In running cornices which are to be enriched, the plas- 
 terer takes care to have proper projections in the runniiig- 
 
AND MACHINIST. 
 
 617 
 
 mould, so as to make a groove in the cornice, for the recep- 
 tion of the cast ornament, which is laid in and secured by 
 spreading a small quantity of liquid plaster of Paris on its 
 back. Detached ornaments intended for ceilings or other 
 parts, and where no running mould has been employed, are 
 cast in pieces corresponding with the design, and fixed upon 
 the ceiling, &c. with white-lead, or with the composition 
 known by the name of iron-cement. 
 
 The manufacture of stucco has, for a long time past, at- 
 tracted the attention of all connected with this branch of 
 building, as well as chemists and other individuals ; but the 
 only benefit resulting from such investigation is, a more ex- 
 tensive knowledge of the materials used. It would seem, 
 that the great moisture of our climate prevents its being 
 brought to any high degree of perfection ; though, among 
 the various compositions which have been tried and pro- 
 posed, some, comparatively speaking, are excellent. 
 
 Common stucco, used for external work, consists of clean 
 washed Thames sand and ground Dorking lime, which are 
 mixed dry, in the proportion of three of the latter to one of 
 the former : when well incorporated together, these should 
 be secured from the air in casks till required for use. Walls 
 to be covered with this composition, must first be prepared, 
 by raking the mortar from the joints, and picking the bricks 
 or stones, till the whole is indented : the dust and other 
 extraneous matter must then be brushed oIF, and the wall 
 W'ell saturated with clean water. The stucco is supersatu- 
 rated with water, till it has the appearance and consistence 
 of ordinary white-w'ash, in which state it is rubbed over the 
 wall with a flat brush of hogs’ bristles. When this process, 
 called roughing in, has been performed, and the work has 
 become tolerably dry and hard, which may be known by its 
 being more white and transparent, the screeds are to be 
 formed upon the wall with fresh stucco from the cask, tem- 
 pered with water to a proper consistency, and spread on the 
 upper-part of the wall, about eight or nine inches wide ; as 
 also against the two ends, beginning at the top and proceeding 
 downwards to the bottom. In this operation, two workmen 
 are required ; one to supply the stucco, the other to apply 
 the plumb-rule and straight-edge. When these are truly 
 formed, other screeds must be made in a vertical direction, 
 about four or five feet apart, unless apertures in the wall 
 prevent it, in which case, they must be formed as near toge- 
 ther as possible. When the scrceding is finished, compo is 
 prepared in larger quantities, and both the workmen spread 
 
618 
 
 THE operative mechanic 
 
 it with their trowels over the wall in the space left between 
 each pair of screeds. When this operation is complete, the 
 straight-edge is applied, and dragged from the top to the 
 bottom of each pair, to remove whatever superfluous stucco 
 may project above the screeds. If there be any hollow 
 places, fresh stucco is applied, and the straight-edge is again 
 drawn over the spot, till the compo is brought even to the 
 face of the screeds, and the whole is level with the edge of the 
 rule. Another interval is then filled up, and Ihe workmen 
 thus proceed till the whole of the wall is covered. The 
 wall is finished by floating, that is, hardening the surface, 
 by sprinkling it with water, and rubbing it with the com- 
 mon wood-float, which is performed similarly to trowelling 
 stucco. 
 
 This description of compo is frequently used by plas- 
 terers for cornices and mouldings, in the same manner as 
 described in common plastering; but if the workman finds 
 it necessary, he may add a small quantity of plaster of Paris, 
 to make it fix the better while running or working the 
 mould. Such addition is not, however, calculated to give 
 strength to the stucco, and is only made through the neces- 
 sity of having a quick set. 
 
 In the year 1796, Mr. Parker obtained a patent for a cement 
 that is impervious to water, and which may be successfully 
 employed in ice-houses, cisterns, tanks, &c. In his speci- 
 fication Mr. Parker states, that nodules of clay, or argil- 
 laceous stone, generally contain water in their centre, sur- 
 rounded by calcareous crystals, having veins of calcareous 
 matter. They are formed in clay, and are of a brown 
 colour like the clay.” These nodules he directs should, after 
 being broken into small pieces and burnt in a kiln, with a heat 
 that is nearly sufficient to vitrify them, be reduced to pow- 
 der : when two measures of water added to five of this 
 powder, will produce tarras. Lime and other matters may 
 be added or withheld at pleasure ; and the proportion of 
 w’ater may be varied. 
 
 The term of the patent being now expired, many other 
 manufactories of this cement have been established, which 
 produce it of equal goodness, and some of them of rather 
 better colour, which is of importance, since the fresco- 
 painting or white- wash, laid on Mr. Parker’s composition, is 
 soon taken off by the rain, and leaves the walls of a dingy 
 and unpleasant appearance. 
 
 The fresco-painting, or staining, is laid on the walls co- 
 vered with this cement, to give them the appearance of 
 
AND MACHINIST. 
 
 619 
 
 stone buildings 5 and is performed by diluting snlphuric acid, 
 {oil of vitriol,) with water, and adding fluid- ochres, &c. of 
 the required tint. 
 
 When stucco is washed over with this mixture, the affinity 
 existing in the iron of the cement ceas''s; and the acid and 
 colour suspended in and upon the stucco are fixed. When 
 dexterously managed, the surface assumes the appearance 
 of an ashlar bond of masonry. 
 
 Scagliola is a distinct branch of plastering, discovered or 
 invented, and much used in Italy, and thence introduced 
 into France, where it obtained its name : the late Mr. H. 
 Holland, who introduced it into England engaged artists 
 from Paris, some of whom, finding a demand for their labour, 
 remained in this country, and instructed the natives in 
 the art. 
 
 Columns and pilasters are executed in this branch of 
 plastering in the following manner : A wooden cradle, 
 
 composed of thin strips of deal, or other wood, is made to 
 represent the column designed ; but about two inches and a 
 half less in diameter than the shaft is intended to be when 
 finished. This cradle is lathed round, as for common plas- 
 tering, and then covered with a pricking up coat of lime 
 and hair. When this is quite dry, the artists in scagliola 
 commence operations, by imitations of the most rare and 
 precious marbles, with astonishing and delusive effect ; in- 
 deed, as the imitation takes as high a polish, and feels 
 as cold and hard as the most compact and solid marble, 
 nothing short of actual fracture can possibly discover the 
 counterfeit. 
 
 In preparing the scagliola, the w^orkman selects, breaks, 
 and calcines the purest gypsum, and as soon as the largest 
 fragments, in the process of calcination, lose their brilliancy, 
 withdraws the fire, and passes the calcined powder through 
 a very fine sieve, and mixes it, as required for use, with a 
 solution of glue, isinglass, &c. In this solution the colours 
 required in the marble to be imitated are diffused ; but 
 when the work is to be of various colours, each colour is 
 prepared separately, and afterwards mingled and combined, 
 nearly in the same manner as a painter mixes on his palette 
 the primitive colours to compose his different tints. 
 
 When the powdered gypsum is prepared, it is laid on the, 
 shaft of the intended column, over the pricked- up coat of 
 lime and hair, and is then floated wdth moulds of wood, 
 made to the requisite size : the artist uses the colours neces- 
 sary for the imitation during the floating, by which means 
 
620 THE OPERATIVE MECHANIC 
 
 tliey mingle and incorporate with the surface. To obtain 
 the glossy lustre, so much admired in works of marble, the 
 workman rubs the work with one hand with a pumice-stone, 
 while with the other he cleans it with a wet sponge : he 
 next polishes it with tripoli, charcoal, and a piece of fine 
 linen; afterwards with a piece of felt dipped in a mixture 
 of oil and tripoli, and finally completes the work by the ap- 
 plication of pure oil. This imitation is, certainly, the most 
 complete that can be conceived ; and when the bases and 
 capitals are made of real marble, as is the common practice, 
 the deception is beyond discovery. If not exposed to the 
 w^eather, it is, in point of durability, little inferior to real 
 marble, retains its lustre full as long, and is not one-eighth 
 of the expense of the cheapest kind. 
 
 There is another species of plastering, used in the deco- 
 rative parts of architecture, and for the frames of pictures, 
 looking-glasses, &c. which is a perfectly distinct branch of 
 the art. This composition, which is very strong, and, when 
 quite dry, of a brownish colour, consists of the proportion 
 of two pounds of powdered whiting, one pound of glue in 
 solution, and half a pound of linseed oil, mixed together, 
 and heated in a copper, and stirred with a spatula, till the 
 whole is incorporated. When cool, it is laid upon a stone, 
 
 ’ covered with powdered whiting, and beaten fill it assumes a 
 tough and firm consistence; after w^hich it is covered with 
 wet cloths, to keep it fresh, till required for use. 
 
 The ornaments to be cast in this composition, are mo- 
 delled in clay, as in common plastering, and afterwards a 
 cameo, or mould, is carved in box-wood. This carving 
 requires to be done with the utmost care, otherwise the 
 symmetry of the ornament which is to be cast from it will 
 be spoiled. The composition, when required for use, is cut 
 with a knife into pieces of the requisite size, and forced 
 into the mould ; after which it is put into a press, worked 
 by an iron screw, and still further compressed. When 
 the mould is taken from the press, the composition, which 
 is generally cast about a foot in length, is dislodged from the 
 mould, and the superfluous parts pared off with a knife, and 
 cast into the copper for the next supply. 
 
 The ornaments thus formed, are glued upon wooden, or 
 other grounds, or fixed by means of white lead, &c. ; after 
 which they are painted or gilt, according to the purposes for 
 which they are intended. This composition is at least 80 
 per cent, cheaper than carving, and, in most cases, equally 
 calculated to answer all the purposes of the art. 
 
AND MACHINIST. 
 
 It is much to be wished, that the art of plastering could 
 be restored to its ancient perfection ; for the Romans pos- 
 sessed an art of rendering works of this kind much more 
 firm and durable than can be accomplished at the present 
 time. 
 
 The specimens of ancient Roman plastering still visible, 
 which have not been injured by force, are found to be firm 
 and solid, free from cracks or crevices, and as smooth and 
 polished on the surface as when first applied. The sides 
 and bottoms of the Roman aqueducts were lined with this 
 plastering, and endured many ages. 
 
 At Venice, some of the roofs of houses, and the floors of 
 rooms, are covered with a sort of plaster of later date, and 
 yet strong enough to endure the sun and weather for several 
 ages, without either cracking or spoiling. 
 
 The method of making the Venetian composition is not 
 known in England ; but such might probably be made by heat- 
 ing the powder of gypsum over afire, and when boiling, which 
 it will do without the aid of water, or other fluid, mixing it with 
 resin, or pitch, or both together, with common sulphur, and 
 the powder of sea-shells. If these be mixed together, water 
 added to it, and the composition kept on the fire till the instant 
 of its being used, it is not improbable that the secret may be 
 discovered. Oil of turpentine and wax, which are the com- 
 mon ingredients in such cements as are accounted firmest, 
 may also be tried as additions ; as also may strong ale wort, 
 which is by some directed to be used instead of water, to 
 make mortar of lime-stone of more than ordinary strength. 
 
 SLATING, 
 
 This brancn of ouilding, which is principally employed in 
 the covering of roofs, is not unfrequently combined with 
 that of plastering. The slates chiefly used in London are 
 brought from the quarries at Bangor, in Caernarvonshire, 
 which supply all parts of the United Kingdom. Another 
 kind of slate, of a pale blue-green colour, is used, and most 
 esteemed, being brought from Kendal, in Westmoreland, 
 called Westmoreland slates* These slates are not large; 
 but of good substance, and well calculated to give a neat 
 appearance to a roof. The Scottish slate, which assimilates 
 in size and quality to a slate from Wales, called ladies, is in 
 little repute. 
 
622 THE OPERATIVE MECHANIC 
 
 Slaters class the Welsh slates in the following order : 
 
 
 Ft. 
 
 In. 
 
 
 Ft. 
 
 In. 
 
 Doubles, average size, 
 
 1 
 
 1 
 
 by 
 
 0 
 
 G 
 
 Ladies, 
 
 1 
 
 3 
 
 
 0 
 
 S 
 
 Countesses, 
 
 1 
 
 8 
 
 — 
 
 0 
 
 10 
 
 Duchesses, 
 
 2 
 
 0 
 
 — 
 
 1 
 
 0 
 
 Welsh rags, 
 
 3 
 
 0 
 
 — 
 
 2 
 
 0 
 
 Queens, 
 
 3 
 
 0 
 
 — 
 
 2 
 
 0 
 
 Imperials, 
 
 2 
 
 G 
 
 — 
 
 2 
 
 0 
 
 Patent slate, 
 
 2 
 
 6 
 
 — 
 
 2 
 
 0 
 
 The doubles, are made from fragments of the larger kinds, 
 and derive their name from their diminutive size. Ladies 
 are similarly obtained. Comitesses are a gradation above 
 ladies and duchesses above countesses. 
 
 Slate, like most other stony substances, is separated from 
 its bed by the ignition of gunpowder. The blocks, thus 
 obtained, are, by the application of wedges, reduced into 
 layers, called scantlings, from four to nine inches in thick- 
 ness, and of any required length and breadth, which arc 
 afterwards sawn to the respective sizes by machinery. The 
 blue, green, and purple, or darker kinds of slate, are, in 
 general, found capable of being split into very thin laminae, 
 or sheets ; but those of the white or brownish free-stone 
 kind, can seldom be separated or divided so fine; conse- 
 quently, these last form heavy, strong, thick coverings, pro- 
 per for buildings in exposed situations, such as barns, stables, 
 and other out-houses. 
 
 The instruments used in splitting and cleaning slates are, 
 slate-knives, axes, bars, and wedges ; the three first being 
 used to reduce the slates into the required thicknesses, and 
 the last to remove the inequalities from the surface. 
 
 Imperial slating is particularly neat, and may be known 
 by having its lower edge sawn ; whereas all other slates 
 used for covering are chipped square on their edges only. 
 
 Patent slate was first brought into use by Mr. Wyatt, the 
 architect ; but a patent was never obtained. It derives its 
 name from the mode adopted to lay it on roofs ; it may be 
 laid on a rafter of much less elevation than any other, and 
 is considerably lighter, by reason of the laps being less than 
 is necessary for the common sort of slating. This slating 
 was originally made from Welsh rags ; but is now ver} 
 frequently made from Imperials, which render it lighter, and 
 also somewhat neater in appearance. 
 
 Westmoreland slate, ivom the experiments made by the late 
 Bishop of Landaff, appears to differ little in its natural com- 
 position from that obtained from Wales. It must, however 
 
AND MACHINIST. 
 
 623 
 
 •be remarked, that this kind of slate owes its lightness, not 
 so much to any diversity in the component parts of the 
 stone, as to the thinness to which it is reduced by the work- 
 men ; consequently, it is not so well calculated to resist 
 violent winds as those which are heavier. 
 
 Slates, when brought from the quarry, are not sufficiently 
 square for the slater’s use ; he therefore picks up and exa- 
 mines the slates separately, and observes which is the 
 strongest and squarest end ; then, seating himself, he holds 
 the slate a little slanting upon, and projecting about an inch 
 over, the edge of a small block of wood, which is of the 
 same height as his seat, and cuts away and makes straight 
 one of its edges; then, with a slip of wood, he gauges, and 
 cuts off* the other edge parallel to it, and squares the end. 
 The slate is now considered prepared for use, with the 
 exception of perforating through its opposite ends two small 
 holes, for the reception of the nails which are to confine it 
 to the roof. Copper and zinc nails, or iron nails tinned, arc 
 considered the best, being less susceptible of oxidation than 
 nails made of bar iron. 
 
 Before we proceed further with the operations necessary 
 in the slating of building, we shall give some account of the 
 tools used by this class of artificers. 
 
 . Slaters’ tools are very few, which sometimes are found by 
 the masters, and sometimes by the men. The tool called 
 the saixe, is made of tempered iron, about sixteen inches in 
 length, and two inches in width, somewhat bent at one end, 
 with a handle of wood at the other. This tool is not unlike 
 a large knife, except that it has on its back a projecting piece 
 of iron, about three inches in length, drawn to a sharp 
 point. This tool is used to chip or cut all the slates to the 
 required sizes. 
 
 The ripper is also of iron, about the same length as the 
 saixe ; it has a very thin blade, about an inch and three- 
 quarters wide, tapered, somewhat towards the top, where a 
 round head projects over the blade about half an inch on 
 each side : it has also two little round notches in the two 
 internal angles at their intersections. The handle of this 
 tool is raised above the blade by a shoulder, which enables 
 the workman to hold it firm. This instrument is used in 
 repairing old slating, and the application consists in thrust- 
 ing the blade under the slates, so that the head, which pro- 
 lects, may catch the nail in the little notch at its intersec- 
 tion, and enable the workman to draw it out. During this 
 
624 THE OPERATIVE MECHANIC 
 
 operation the slate is sufficiently loosened to allow of its 
 being removed, and another inserted in its place. 
 
 The hammer, which is somewhat different in shape to the 
 ordinary tool of that name, is about five inches in height 
 on the hammer, or driving part, and the top is bent back, and 
 ground to a tolerably sharp point, its lower or flat end, 
 which is quite round, being about three-quarters of an inch 
 in diameter. On this side of the driving part is a small 
 projection, with a notch in the centre, which is used as a 
 claw to extract such nails as do not drive satisfactorily. 
 
 The shaving-tool is used for getting the slates to a smooth 
 face for skirtings, floors of balconies, &c. It consists of an 
 iron blade, sharpened at one of its ends like a chisel, and 
 mortised through the centre of two round wooden handles, 
 one fixed at one end, and the other about the middle of the 
 blade. The blade is about eleven inches long, and two inches 
 wide, and the handle is about ten inches long, so that they 
 project about four inches on each side of the blade. In using 
 this tool, the workman places one hand on each side of the 
 handle that is in the middle of the blade, and allows the 
 other to press against both his wrists. In this manner he 
 removes all the uneven parts from off the face of the slate, 
 and gets it to a smooth surface. 
 
 The other tools used by the slater consist of chisels, 
 gouges, and files of all sizes ; by means of which he finishes 
 the slates into mouldings and other required forms. 
 
 In slating roofs, it is necessary to form a base or floor for 
 the slates to lay compactly and safely upon ; for doubles and 
 ladies, boarding is required, which must be laid very even, 
 witli the joints close, and properly secured by nails to the 
 rafters. This being completed, the slater provides himself 
 with several slips of wood, tilting fillets, dhoxxi ten 
 
 inches and a half wide, and three-quarters of an inch 
 thick on one edge, and chamfered to an arris on the other, 
 which he nails down all round the extreme edges of the 
 roof, beginning with the hips, if any, and if not, with the 
 sides, eaves, and ridge. He next selects the largest of the 
 slates, and arranges them regularly along the eaves with 
 their lower edges to a line, and nails them to the boarding. 
 Til is part of the work being completed, he takes other 
 slates to form the bond to the under sides of the eaves, and 
 places them under those previously laid,- so as to cross and 
 cover all their joints. Such slates are pushed up lightly 
 under tliose which are above them, and are seldom nailed, 
 but left dependent for support on the weight of those above 
 
AND MACHINIST. 
 
 G-2j 
 
 tliem. and their own weight on the boarding. The countessc.^ 
 and all other description of slates^ when intended to be luid 
 in a good manner, are also laid on boards. 
 
 Wdieri the slater has finished the eaves, he strains a line 
 on the face of the upper slates, parallel to its outer edge, 
 and as far from it as he cieems sufiTicient for the lap of those 
 he intends shall form the next course, which is laid and 
 nailed even with the line, crossing the joints of the upper 
 slates of the eaves. This lining and laying is continued 
 close to the ridge of the roof, observing throughout to cross 
 the different joints, by laying the slates one above another. 
 The same system is uniformly followed in laying ail the 
 different sorts of slates, with the exception of those called 
 patent slates, as are hereafter explained. 
 
 Tlie largest kinds of slate, are found to lay firm on hat-^ 
 tens, which are, consequently, much employed, and pro- 
 duce a very considerable saving of expense in large build- 
 ings. A batten is a narrow portion of deal, about two 
 inches and a half, or three inches wide ; four of them being’' 
 commonly procured from an eleven inch board. 
 
 For countess slates, battens three-quarters of an inch 
 thick, will be of adequate substance ; but for the larger and 
 heavier kinds, inch battens will be necessary. In battening 
 a roof for slates, the battens are not placed at an uniform 
 distance from each other, but so as to suit the length of the 
 slates ; and as tliese vary as they approach the apex, or ridge 
 of the roof, it follows that the slater himself is the best 
 judge where to fix them, so as best to support the slates. 
 
 A roof, to be covered with patent slates, requires that the 
 common rafters be left loose upon their purlines, as they 
 must be so arranged that a rafter shall lie under every one of 
 the meeting-joints. Neither battening nor bearding is re- 
 quired for these slates. The number of rafters will depend 
 on the width of the slates ; hence if they be of a large size, 
 very few will siiftice. This kind of slating is likewise com- 
 menced at the caves ; but no crossing or bonding is re- 
 quired, as the slates are laid uniformly, with each end reach- 
 ing to the centre of the rafter, and butted up to each other 
 throughout the length of thereof. When the eaves-course 
 is laid, the slates which compose it are screwed down to 
 the rafters by two or three strong inch and half screws at 
 each of their ends. A line is then strained about two 
 inches below the upper edge, in order to guide the laying 
 of the next course, which is laid with its lower edge touch 
 ing the line. This lining, laying with a lap, and screwed 
 
62(3 
 
 THE OPERATIVE MECHANIC 
 
 down, is continued till the roof is completely covered. The 
 joints are then secured by filletting, which consists in cover- 
 ing all the meeting-joints with fillets of slate, bedded in 
 glazier’s putty, and screwed down through the whole into 
 the rafters. The fillets are usually about three inches wide, 
 and of a length proportionate to that of the slates, whose 
 joints they have to cover. These fillets are solidly bedded 
 in the putty, and their intersecting joints are lapped similar 
 to those of the slates. The fillets being so laid, and secured 
 by one in the middle of the fillet and one in each lap, are 
 next neatly pointed all round their edges with more putty, 
 and then painted over with the colour of the slate. The hips 
 and ridges of such slating are frequently covered by fillets, 
 which produces a veiy neat effect; but lead, which is not 
 much dearer, is by far the best kind of covering for all hips 
 and ridges. The patent slating may be laid so as to be per- 
 fectly water-tight, with an elevation of the rafters consider- 
 ably less than for any other slate or tile covering. The rise 
 in each foot of length in the rafter is not required to be 
 more than two inches, which, in a rafter of fifteen feet, will 
 amount to only two feet six inches : a rise scarcely percep- 
 tible from the ground. 
 
 Slating is performed in several other ways, but the prin- 
 ciples already explained, embrace the most of them. Some 
 workmen shape and lay their slates in a lozenge form. This 
 kind of work consists in getting all the slates to an uniform 
 size, of the shape of a geometrical square. When laid on 
 the roof, which must be boarded, they are bonded and lap- 
 ped as in common slating, observing only to let the elbow, 
 or half of the square, appear above each slate that is next 
 beneath it, and be regular in the courses all over the roof. 
 One nail or screw only can be used for such slating ; hence 
 it soon becomes dilapitated. It is commonly employed in 
 {)laces near to tlie eye, or wdiere particular neatness is re- 
 quired. 
 
 It has been ascertained, that a slate one inch thick will, 
 in an horizontal jiosition, support as much, in weight, as 
 five inches of Portland stone similarly suspended. Hence 
 slates are now wrought and used in galleries, and other pur- 
 poses, where it is essential to have strength and lightness 
 combined. 
 
 Slates are also fashioned into chimney-pieces ; but are in- 
 capable of receiving a polish like marble. It makes excel- 
 lent skirtings of all descriptions, as well as casings to walls, 
 where dilapidations, or great wear and tear are to be ex- 
 
AND MACHINIST. 
 
 627 
 
 pected. For these purposes, it is capable of being fixed with 
 joints, equally as neat as wood : and may, if required, be 
 painted over so as to appear like it. Stair-cases may also 
 be executed in slate, which will produce a resemblance of 
 marble. 
 
 MENSURATION OF PLASTERERS* AND SLATERS* WORK. 
 
 ' Plasterers* work is executed by the yard square ; and the 
 dimensions are taken in feet and inches. 
 
 If a room consists of more than four quoins, the addi- 
 tional corners must be allowed at per foot run. 
 
 In measuring ceilings with ribs, the superficies must be 
 taken for plain work ; then an allowance must be made for 
 each mitre, and the ribs must be valued at so much per foot 
 run, according to the girth ; or by the foot superficial, al- 
 lowing moulding work. 
 
 In measuring common work the principal things to be 
 observed are as follow : — first, to make deductions for 
 chimneys, windows, and doors ; secondly, to make deduc- 
 tions for rendering upon brick work, for doors and windows ; 
 thirdly, if the workman find materials for rendering between 
 quarters, one-fifth must be added for quarters ; but if work- 
 manship only is found, the whole must be measured as whole 
 work, because the workman could have performed the 
 whole much sooner if there had been no quarters ; fourthly, 
 all mouldings in plaster work are measured by the foot su- 
 perficial, the same as joiners, by girting over the mouldings 
 with a line. 
 
 Slaters* work is measured and reduced into squares, con- 
 taining 100 feet superficial. If in measuring the slating on 
 a roof, it be hipped on all sides with a flat at top, and the 
 planof the building be rectangular, add thelengthand breadth 
 of two adjoining sides of the eaves, and the length and 
 breadth of two adjoining sides at the flat together, multiply 
 the sum by the breadth of the slope, and the product will 
 give the area of the space that is covered. Add the number 
 of square feet produced, by multiplying the girts of the roof 
 by the length of the slates at the eaves ; to the area also, for 
 the trouble of putting on the double row of slates, add the 
 number of square feet produced by multiplying the length 
 of the hips by one foot in breadth, and the sum 'will be the 
 whole contents, and yield a compensation for the trouble 
 and waste of materials. If there be no flats, add the two 
 adjoining sides and twice the length of the ridge for the 
 length ; multiply the sum by the breadth of the slips, for, 
 
 2s 2 
 
628 
 
 THE OPERATIVE MECHANIC 
 
 the area of the space covered^ and add the allowances as 
 before. 
 
 Another plan is to allow in addition to the nett dimen- 
 sions of the work^ six inches for all the eaves, and four 
 inches for the hips. 
 
 All faced work in slate skirting, stair-cases, galleries, &c. 
 is charged by the foot superficial, without any addition. 
 
 PLUMBING, 
 
 Is the art of casting and working in lead, and using the 
 same in the covering and for other purposes in building. 
 
 To the plumber is also confided the pump-work, as well 
 as the making and forming of cisterns and reservoirs, large 
 or small closets, &c. for the purposes of domestic (economy. 
 The plumber does not use a great variety of tools, because the 
 ductility of the metal upon which he operates does not re- 
 quire it. 
 
 The tools used, consist of an iron hammer, rather heavier 
 than a carjienter’s, with a short thick handle ; two or three 
 wooden mallets of different sizes ; and a dressing and flat- 
 ting tool. 
 
 This last is of beech, about eighteen inches long, and two 
 inches square, planed smooth and flat on the under surface, 
 rounded on the upper, and one of its ends tapered off rouncl 
 as a handle. With this tool he stretches out and flattens 
 the sheet-lead, or dresses it to the shape required, using 
 first the flat side, then the round one, as occasion may re- 
 quire. 
 
 The plumber has also occasion for a jack and trying plane, 
 similar to that of the carpenter. 
 
 With this he reduces the edges of sheet-lead to a straight 
 line, Avhen the purposes to which it is to be applied re- 
 (|uire it. 
 
 Also a chalk line, wound upon a roller, for marking out 
 the lead into such breadths as he may want. 
 
 His cutting tools consist of a variety of chisels and gouges 
 as well as knives. 
 
 The latter of these are used for cutting the sheet lead into 
 slips and jiieces after it has been marked out by the chalk 
 line. 
 
 Files of different sizes ; ladles of three or four sizes, for 
 melting the solder ; and an iron instrument called grazing- 
 iro7is. 
 
AND MACHINIST. 
 
 629 
 
 These grozing-irons are of several sizes, generally about 
 twelve inches in length, tapered at both ends, the handle 
 end being turned quite round, to allow of its being firmly 
 held while in use : the other end is a bulb of a spindle, or 
 spherical shape, of a size proportioned to the soldering in- 
 tended to be exeeuted. They are, when required for use, 
 heated to redness. 
 
 The plumber’s measuring rule is two feet in length, di - 
 vided into three equal parts of eight inches each ; two of 
 its legs are of box-wood, daodecimally divided ; and the 
 third consists of a piece of slow tempered steel, attached to 
 one of the box legs by a pivot on which it turns, and falls, 
 when not in use, into a groove cut in such leg for its recep- 
 tion. This steel leg can be passed into places where the others 
 cannot enter ; and it is also useful for occasionally removing 
 the oxide or any other extraneous matters from the surface 
 of the heated metal. 
 
 Scales and weights are also necessary ; and he must be 
 supplied with centre-bits of all sizes ; and a stock to work 
 them, for the purpose of making perforations in lead or 
 wood, through which he may want to insert pipes, &c. 
 Compasses, to strike circular pieces, to line or cover figures 
 of that shape, are occasionally required. 
 
 Lead is obtained from ore, and, from its being generally 
 combined with sulphur, it has been denominated sulphu- 
 ret,'' After the ore has been taken from its bed it is smelted, 
 first being picked, in order to separate the unctuous and rich, 
 or genuine ore from the stony matrix, and other impurities ; 
 the picked ore is then pounded under stampers worked by 
 machinery, and afterwards washed to carry off the remaindeV 
 of the matrix, which could not be separated in picking. It is 
 next put into a reverberatory furnace, to be roasted ; during 
 which operation, it is repeatedly stirred, to facilitate the 
 evaporation of the sulphur. When the surface begins to 
 assume the appearance of a paste, it is covered with char- 
 coal, and well shaken together : the fire is then increased, 
 and the purified lead flows down on all sides into the basin 
 of the furnace, whence it runs off into moulds prepared for 
 its reception. The moulds are capable of receiving 1541bs. 
 of lead each, and their contents, when cool, are, in the com- 
 mercial world, called 
 
 Lead is of a bluish-white colour, and when newly melt- 
 ed, or cut, is quite bright ; but it soon becomes tarnished 
 on exposure to the atmosphere ; assuming first a dirty grey 
 colour, and afterwards becomes white. It is capable of 
 
630 
 
 THE OPERATIVE MECHANIC 
 
 being hammered into very thin plates, and may be drawn 
 into wire ; but its tenacity is very inferior to that of other 
 metals ; for a leaden wire, the hundred and twentieth part 
 of an inch in diameter, is only capable of supporting about 
 18lb. without breaking. Lead, next to tin, is the most fu- 
 sible of all metals ; and if a stronger heat be applied, 
 it boils and evaporates. If cooled slowly, it crystallizes. 
 The change of its external colour is owing to its gradual 
 combination with oxygen, 'which converts its exterior sur- 
 face into an oxyd. This outward crust, however, preserves 
 the rest of the metal for a long time, as the air can pene- 
 trate but very slowly. 
 
 Lead is not acted upon immediately by water, though that 
 clement greatly facilitates the action of the air upon it : for 
 it is known that, when lead is exposed to the atmosphere, 
 and kept constantly wet, the process of oxidation takes 
 place much more rapidly than it does under other circum- 
 stances : hence the white crust that is to be observed on 
 the sides of leaden vessels containing water, just at the 
 place where the surface of the w^ater terminates. 
 
 Lead is purchased by plumbers, in pigs, and they reduce 
 it into sheets or pipes, as they have occasion. Of sheet-lead 
 they have two kinds, cast and milled. The former is used 
 for covering flat roofs of buildings, laying of terraces, form- 
 ing gutters, lining reservoirs, &c. ; and the latter, which is 
 very thin, for covering the hips and ridges of roofs. This 
 last they do not manufacture themselves, but purchase it 
 of the lead merchants, ready prepared. 
 
 For the casting of sheet lead, a copper is provided, and well 
 fixed in masoniy, at the upper end of the workshop, near 
 the mould or casting table, which consists of strong deal 
 boards, well jointed together, and bound with bars of iron 
 at the ends. ITie sides of this table, of which the shape is 
 a parallelogram, vary in size from four to six feet in width, 
 and from 10 to 18 feet and upwards in length, and are guarded 
 by a frame or edging of wood, 3 inches thick, and 4 or 5 
 inches higher than the interior surface, called the shafts, 
 This table is fixed upon firm legs, strongly framed together, 
 about 6 or 7 inches lower than the top of the copper. At 
 the upper end of the mould, nearest the copper, is a box, 
 called the pan, which is adapted in its length to the breadth 
 of the table, having at its bottom a long horizontal slit, 
 from which the heated metal is to issue, when it has been 
 poured in from the copper. This box moves upon rollers 
 along the surface of the rim of the table, and is put in mo- 
 
AND Machinist. 
 
 631 
 
 tioii by means of .ropes and pulleys, fixed to beams above. 
 While the metal is melting, the surface of the mould, or 
 table, is prepared by covering it with a stratum of dry and 
 clean sand, regularly smoothed over with a kind of rake, 
 called a strike, which consists of a board about 5 inches 
 broad, and rather longer than the inside of the mould, so 
 that its ends, which are notched about two inches deep, may 
 ride upon the shafts. This being passed down the whole 
 length of the table, reduces the sand to an uniform sur- 
 face. The pan is now brought to the head of the table, close 
 to the copper, its sides having previously been guarded by a 
 coat of moistened sand, to prevent its firing from the heat of 
 the metal, which is now put in by ladles from the copper. . 
 
 These pans, or boxes, it must be observed, are made to 
 contain the quantity of melted lead which is required to cast 
 a whole sheet at one time ; and the slit in the bottom is so 
 adjusted as to let out, during its progress along the table, 
 just as much as will completely cover it of the thickness and 
 weight per foot required. Every thing being thus prepared, 
 the slit is opened, and the box moved along the table, dis- 
 pensing its contents from the top to the bottom, and leaving 
 in its progress a sheet of lead of the desired thickness. 
 When cool, the sheet is rolled up and i-emoved from the 
 table, and other sheets are cast, till all the metal in the cop- 
 per is exhausted. The sheets thus formed are then rolled 
 up and kept for use. 
 
 In some places, instead of having a square box upon 
 wheels, with a slit in the bottom, the pan consists of a kind 
 of trough, being composed of two planks nailed together at 
 right angles, with two triangular pieces fitted in between 
 them, at their ends. The length of this pan, as well as that 
 of the box, is equal to the whole breadth of the mould. It 
 is placed with its bottom on a bench at the head of the table 
 leaning wdth one side against it : to the opposite side is fixed 
 a handle, by which it may be lifted up in order to pour out 
 the liquid metal. On the side of the pan next the mould 
 are two iron hooks, to hold it to the table, and prevent it 
 from slipping while the metal is being poured into the 
 mould. 
 
 The mould, as well as the pan, is spread over, about two 
 inches thick, with sand, sifted and moistened, and rendered 
 perfectly level by moving over it the strike, and smoothing it 
 down with a plane of polished brass, about a quarter of an 
 inch thick, and nine inches square, turned up on the edges. 
 
 . Before they proceed to casting the lead, the strike is made 
 
6132 TUB OPERATIVE MECHANIC 
 
 ready by tacking two pieces of old hat on the notches^ or 
 by covering the notches with leather cases, so as to raise the 
 under side of the strike, about an eighth of an inch, or 
 more, above the sand, according to the proposed thickness 
 of the sheet. The face or under side of tlie strike is then 
 smeared with tallow, and laid across the breadth of the 
 mould, with its ends resting on the shafts. The melted lead 
 is then put into the pan with ladles ; and, when a sufficient 
 quantity has been put in, the scum is swept off with a piece 
 of board, and suffered to settle on the coat of sand, to 
 prevent its falling into the mould, when the metal is poured 
 out. It generally happens, that the lead, when first taken 
 from the copper, is too hot for casting ; it is therefore suf- 
 fered to cool in the pan, till it begins to stand with a shell 
 or wail on the sand with which the pan is lined. Two men 
 then take the pan by the handle, or one of them takes it by 
 means of a bar and chain fixed to a beam in the ceiling, and 
 turn it down, so that the metal runs into the mould : while 
 another man stands ready with the strike, and, as soon as 
 all the metal is poured in sweeps it forward and draws the 
 residue into a trough at the bottom, which has been prepa- 
 red to receive it. The sheet is then rolled up, as before. 
 
 In this mode of operation, the table inclines in its 
 length about an inch, or an inch and a half, in the length of 
 sixteen or seventeen feet, or more, according to the required 
 thickness of the sheets ; the thinner the sheet the greater 
 the declivity; and vice versa. The lower end of the mould 
 is also left open, to admit of the superfluous metal being 
 thrown off. 
 
 When a cistern is to be cast, the size of the four sides is 
 measured out; and the dimensions of the front having been 
 taken, sli{5s of wood, on which the mouldings are carved, are 
 pressed uj)on the sand. Figures of birds, beasts, &c. are 
 likewise stamped in the internal area, by means of leaden 
 moulds. If any part of the sand has been disturbed in 
 doing this, it is made smooth, and the process of casting 
 goes on as for plain sheets ; except that, instead of rolling 
 up the lead when cast,it is bent into four sides, so that the 
 two ends, when they are soldered together, may be joined 
 at the back ; the bottom is afterwards soldered up. 
 
 The lead which lines the Chinese tea-boxes is reduced 
 to a thinness which our plumbers cannot, it is said, ap- 
 proach. The following account of the process was commu- 
 nicated by an intelligent East-lndian, in a letter which ap- 
 peared in the Gentleman’s Magazine. The caster sits by 
 
AND MACHlNIf.T. 
 
 G33 
 
 a pot, containing the melted metal, and has two large stones, 
 the lower one fixed and the upper one movable, having 
 their surfaces of contact ground to each other, directly be- 
 fore him. He raises the upper stone by pressing his foot 
 upon its side, and with an iron ladle pours into the opening 
 a sufficient quantity of the fluid metal. He then lets fall 
 the upper stone, and thus forms the lead into an extremely 
 thin and irregular plate, which is afterwards cut into its re- 
 quired form.” 
 
 Cast sheet lead, used for architectural purposes, is techni- 
 cally divided into 51b. 5^lb. 6lb. 6^1b. 71b. 72lh. 8Ib. and 
 8’Ib.; by which is understood, that every superficial foot 
 is to contain those respective weights, according to the price 
 agreed upon. 
 
 The milled lead used by plumbers is very thin, seldom 
 containing more than 51b. to the foot. It is by no means 
 adapted to gutters or terraces, nor, indeed, to any part of a 
 building that is much exposed either to great wear or to the 
 effects of the sun’s rays : in the former case, it soon wears 
 away ; in the latter, it expands and cracks. It is laminated 
 in sheets of about the same size as those of cast lead, by 
 means of a roller, or flatting- mill. 
 
 Lead-pipes, besides the various ways of manufacture de- 
 scribed in page 362, are sometimes made of sheet lead, by 
 beating it on round wooden cylinders of the length and 
 dimensions required, and then soldering up the edges. 
 
 Solder is used to secure the joints of work in lead, 
 which by other means would be impossible. It should be 
 easier of fusion than the metal intended to be soldered, and 
 should be as nearly as possible of the same colour. The 
 plumber therefore uses, what is technically called, soft sol- 
 which is a compound of equal parts of tin and lead, 
 melted together and run in to moulds. In this state it is 
 sold by the manufacturer by the pound. 
 
 In the operation of soldering, the surfaces or edges in- 
 tended to be united are scraped very clean, and brought 
 close up to each other, in which state they are held by an 
 assistant, while the plumber applies a little resin on the 
 joints, in order to prevent the oxidation of the metal. The 
 heated solder is then brought in a ladle and poured on the 
 joint ; after which it is smoothed and finished by rubbing it 
 about with a red-hot soldering iron, and when completed is 
 made smooth by filing. 
 
 In the covering of roofs or terraces with lead, (the sheets 
 never exceeding six feet in breadth,) it becomes necessary in 
 
634 
 
 THE OPERATIVE MECHANIC 
 
 large surfaces^ to have joints ; which are managed several 
 ways, but in all, the chief object is to have them water- 
 tight. The best plan of effecting this, is to form laps or 
 roll joints, which is done by having a roll, or strip of wood, 
 about two inches square, l)ut rounded on its upper side, 
 nailed under the joints of the sheets, where the edges lap 
 over each other ; one of these edges is to be dressed up 
 over the roll on the inside, and the other is to be dressed 
 over them both on the outside, by which means the water 
 is prevented from penetrating. No other fastening is requi- 
 site than what is required from the hammering of the sheets 
 together down upon the flat ; nor should any other be re- 
 sorted to, when sheet lead is exposed to the vicissitudes of 
 the weather ; because it expands and shrinks, which, if pre- 
 vented by too much fastening, would cause it to crack and 
 become useless. It sometimes, however, occurs, that rolls 
 cannot be used, and then the method of joining by seams is 
 resorted to. This consists in simply bending the approxi- 
 mate edges of the lead up and over each other, and then 
 dressing them down close to the flat, throughout their 
 length. But this is not equal to the roll, either for neatness 
 or security. 
 
 Lead flats and gutters should always be laid with a cur- 
 rent, to keep them dry. About a quarter of an inch to the 
 foot run is a sufficient inclination. 
 
 In laying gutters, &c. pieces of milled-lead, called 
 ings, about eight or nine inches wide, are fixed in the walls 
 all round the edges of the sheet-lead, with which the flat is 
 covered, and are suffered to hang down over them, so as to 
 prevent the passage of rain through the interstice between 
 the raised edge and the wall. If the walls have been pre- 
 viously built, the mortar is. raked out of the joint of the 
 bricks next above the edge of the sheet, and the flush- 
 ings are not only inserted into the crack at the upper sides, 
 but their lower edges are likewise dressed over those of 
 the lead in the flat, or gutter. When neither of these 
 modes can be resorted to, the flushings are fastened by 
 wall-hooks, and their lower edges dressed down as before. 
 
 Drips in flats, or gutters, are formed by raising one part 
 above another, and dressing the lead, as already described, 
 for covering the rolls. They are resorted to when the gutter 
 or flat, exceeds the length of the sheet ; or sometimes for 
 convenience. They are also an useful expedient to avoid sol- 
 dering the joints. 
 
 Sheet lead is also used in the lining of reservoirs, which 
 
AND MACHINIST. 
 
 635 
 
 are made cither of wood or masonry. As these conveni- 
 ences are seldom in places subject to material change of 
 temperature, recourse maybe had to the soldering, without 
 fear of its damaging the work, by promoting a disposition 
 to crack. 
 
 The pumps which come under the province of the plum- 
 ber, are confined generally to two or three kinds, used for 
 domestic purposes, of which the suction and lifting pumps 
 are the chief: these, as well as water-closets, are manufac- 
 tured by a particular set of workmen, and sold to the 
 plumber, who furnishes the lead pipes, and fixes them in their 
 places. 
 
 Plumber’s work is generally estimated by the pound, or 
 hundred weight; but the weight may be discovered by 
 measurement, in the following manner : sheet-lead used in 
 roofing and guttering is commonly between seven and 
 twelve pounds to the square foot ; but the following table 
 exhibits the particular weight of a square foot for each of 
 the several thicknesses. 
 
 Thick- 
 
 ness. 
 
 Poundsto 
 a sqr.ft. 
 
 Thick- 
 
 ness. 
 
 Poundsto 
 a sqr. ft. 
 
 .10 
 
 5.899 
 
 .15 
 
 8.848 
 
 .11 
 
 6.489 
 
 .16 
 
 9.438 
 
 ■9 
 
 6.554 
 
 1 
 
 T 
 
 9.831 
 
 .12^ 
 
 7.078 
 
 .17 
 
 10.028 
 
 
 7.373 I 
 
 .18 
 
 10.618 
 
 .13 
 
 7.668 
 
 .19 
 
 11.207 
 
 .14 
 
 8.258 , 
 
 5 
 
 11.797 
 
 • 
 
 T 
 
 1 8.427 ' 
 
 •21 
 
 12.387 
 
 In this table the thickness is set down in tenths and hun- 
 dredths, &c. of an inch ; and the annexed corresponding 
 numbers are the weights in avoirdupois pounds, and thou- 
 sandth parts of a pound ; so that the weight of a square 
 foot of 1-lOth of an inch thick, lO-lOOths, is 5 lbs. and 899 
 thousandth parts of a pound ; and the weight of a square 
 foot l-9th of an inch in thickness, is 6 pounds and 554 
 thousandths of a pound. Leaden pipe of an inch bore, is 
 commonly 13 or 14 lbs. to the yard in length. 
 
 GLAZING. 
 
 The business of this class of artificers consists in putting 
 glass into sashes and casements. Glazier’s work may be 
 classed under three distinct heads, sash- work, lead-work, 
 and fret-work. 
 
636 
 
 THE OPERATIVE MECHANIC 
 
 The tools requisite for the performance of the first of these 
 departments are, a diamond, a ranging lath, a short lath, a 
 square, a rule, a glazing-knife, a cutting- chisel, a heading- 
 hammer, a duster, ana sash-tool ; and in addition, for stop- 
 ping in squares, a hacking-knife and hammer. 
 
 The diamond is a speck of that precious stone, polished 
 to a cutting point, and set in brass on an iron socket, to re- 
 ceive a wooden handle, which is so set as to be held in the 
 hand in the cutting direction. The top of the handle goes 
 between the root of the fore-finger and the middle finger, 
 and the hinder part, between the point of the fore-finger 
 and thumb ; there is, in general, a notch in the side of the 
 socket, which should be held next to the lath. Some dia- 
 monds have more cuts than one. Plough diamonds have a 
 square nut on the end of the socket, next the glass, which, 
 on running the nut square on the side of the lath, keeps it 
 in the cutting direction. 
 
 Glass binders have these plough diamonds without long 
 handles, as, in cutting their curious productions, they can- 
 not apply a lath, but direct them by the point of their mid- 
 dle finger, gliding along the edge of the glass. 
 
 The ranging lath must be long enough to extend rather 
 beyond the boundary of the table of glass. 
 
 Ranging of glass is the cutting it in breadths as the work 
 may require, and is best done by one uninterrupted cut from 
 one end to the other. 
 
 The square is used in cutting the squares from the range, 
 that they may with greater certainty be cut at right angles. 
 The glazing knife is used for laying in the putty in the re- 
 bates of the sash, for binding in the glass, and for finishing 
 the front putty. 
 
 Of the glass used in building, three qualities are in com- 
 mon use, denominated hest^ second, and third. 
 
 The best is that which is the purest metal and free of 
 blemishes, as blisters, specks, streaks, &c. ; the second is 
 inferior, from its not being so free from these blemishes ; and 
 the third are still inferior, both in regard to quality and 
 colour, being of greener hue. 
 
 They are all sold at the same price per crate ; but the 
 number of tables varies according to the quality. Best 
 twelve, second fifteen, and third eighteen tables. 
 
 These tables are circular when manufactured, and about 
 four feet in diameter, having in the centre a knot, to which, 
 in the course of the process, the flashing rod was fixed ; but 
 for the safety of carriage, and convenience of handling, as 
 
AND MACHINIST. 
 
 0S7 
 
 well as utility in practice, a segment is cut off about four 
 inches from the knot. The large piece with the knot, stil 
 retains the name of table ; the smaller piece is technically 
 called a slab. From these tables being of a given size, it is 
 reasonable to suppose that, when the dimensions of squares 
 are such as cut the glass to waste, the price should be ad- 
 vanced. 
 
 A superior kind of glass may be obtained at some of the 
 first houses in London, which is very flat, and of large di- 
 mensions ; some of it being 2 feet 8 inches by 2 feet 1 
 inch ; these are sold only in squares. 
 
 Rough glass is well adapted to baths, and other places of 
 privacy ; one side is ground with emery or sand, so that no 
 objects can be seen through it, though the light be sti-ll 
 transmitted. 
 
 The glass, called German-sheet, is of a superior kind, as 
 it can be had of much larger dimensions than common glass ; 
 it is also of a purer substance, and for these reasons, is fre- 
 quently appropriated to picture frames. Squares may be 
 had at the astonishing size of 3 feet 8 inches, by 3 feet I inch, 
 and 3 feet 10 inches by 2 feet 8 inches, and under. 
 
 The glass is first blown in the form of a globe, and after- 
 wards flatted in a furnace, in consequence of which it has a 
 very forbidding appearance from the outside, the surface 
 being uneven. 
 
 Plate-glass is the most superior in quality, substance, 
 and flatness, being cast in plates, and polished. The 
 quantity of metal it contains, must be almost, if not al - 
 together, colourless ; that sort which is tinged being of an 
 inferior quality. Plate-glass -when used in sashes, is pe- 
 culiarly magnificent ; and it can be had of larger dimen- 
 sions than any other kind of glass. 
 
 Stained-glass is of different colours, as red, orange, yel- 
 low, green, blue, and purple. 
 
 These colours are fixed by burning, and are as durable as 
 the glass. 
 
 Glass can be bent to circular sweeps, which is much used 
 in London for shop windows, and is carried to great per- 
 fection in covers, for small pieces of statuary, &c. 
 
 The application of stained glass to the purposes of glazing 
 is called fret-iuork. This description of work consists of 
 working ground and stained glass, in fine lead, into different 
 patterns. In many cases family arms and other devices are 
 worked in it. It is a branch capable of great improvement ; 
 but at present is much neglected. Old pieces are very much 
 
638 
 
 THE OPERATIVE MECHANK 
 
 esteemed, though the same expense would furnish elegant 
 modern productions. They are placed in halls and stair- 
 case windows, or in some particular church windows. In 
 many instances they are introduced where there is an un- 
 pleasant aspect, in a place of particular or genteel resort. 
 
 Lead- work is used in inferior offices, and is in general 
 practice all through the country. Frames intended to re- 
 ceive these lights are made with bars across, to which the 
 lights are fastened by leaden bars, called saddle bars ; and 
 where openings are wanted, a casement is introduced cither 
 of wood or iron. Sometiiiies a sliding frame answers the 
 same purposes. Church windows are generally made in 
 this manner, in quarries or in squares. 
 
 The tools with which this work is performed are, in ad- 
 dition to the foregoing, as follow : — 
 
 A vice, with ditferent cheeks and cutters, to turn out tiic 
 different kinds of lead as the magnitude of the windoiv or 
 the squares may require. 
 
 The German vices, which are esteemed^ the best, arc 
 furnished with moulds, and turn out lead in a variety of 
 sizes. The bars of lead cast in these vices are received by 
 the mill, which turns them out with two sides parallel to 
 each other, and about | of an inch broad, with a partition 
 connecting the two sides together, about g of an inch wide, 
 forming on each side a groove, nearly -n-r by ^ of an inch, 
 and about 6 feet long. 
 
 Besides a vice and moulds there are setting-hoard, latter^ 
 kin, setting- knife, resin-hox tin, glazing-irons, and clips. 
 
 The setting-hoard is that in which the ridge of the light 
 is marked and divided into squares, struck out with a chalk 
 line, or drawn with a lath, which serves to guide the work- 
 men. One side and end is squared with a projecting bead 
 or fillet. 
 
 The latter kin is a piece of hard wood pointed, to run in 
 the groove of the lead, and widen it for the easier reception 
 of the glass. 
 
 The setting-knife consists of a blade with a round point, 
 loaded with lead at the bottom and terminating in a long 
 square handle. The square end of the liandle serves to 
 force the square of glass tight in the lead. All the inter- 
 sections are soldered on both sides, except the outside 
 joints of the outer sides, that is, where they come to the 
 outer edge. These lights should be cemented by pouring 
 thin paint along the lead bars, and filling up the chasms with 
 dry whiting, to which, after the oil in the paint has se- 
 
AND MACHINIST. 
 
 cso 
 
 creted a little, a little more dry whiting, or white lead, 
 must be added. This will dry hard, and resist the action 
 of the atmosphere. 
 
 MENSURATION OF GLAZIERS* WORK. 
 
 Glaziers* work is measured by superficial feet, and the di- 
 mensions are taken in feet, tenths, &c. For this purpose, 
 their rules are generally divided into decimal parts, and 
 their dimensions squared according to decimals. Circular, 
 or oval windows are measured as if they were rectangular ; 
 because in cutting squares of glass there is a very great 
 waste, and more time is expended than if the window had 
 been of a rectangular form. 
 
 PAINTING, 
 
 As applied to purposes of building, is the application of 
 artificial colours, compounded cither with oil or water, in 
 embellishing and preserving wood, &c. 
 
 This branch of painting is termed economical^ and applies 
 more immediately to the power which oil and varnishes pos- 
 sess, of preventing the action of the atmosphere upon 
 wood, iron, and stucco, by interposing an artificial surface ; 
 but it is here intended to use the term more generally, in 
 allusion to the decorative part, and as it is employed by 
 the architect, throughout every part of his work, both ex- 
 ternally and internally. 
 
 In every branch of painting in oil, the general processes 
 are very similar, or with such variations only, as readily oc- 
 cur to the workman. 
 
 The first coatings, or layers, if on wood or iron, ought al- 
 ways to be of ceruse or white lead, of the best quality, pre- 
 viously ground very fine in nut or linseed oil, either over a 
 stone with a mullcr, or, as that mode is too tedious _for 
 large quantities, passed through a mill. If used on shut- 
 ters, doors, or wainscottings, made of fir or deal, it is very 
 requisite to destroy the effects of the knots ; which are ge- 
 nerally so completely saturated with turpentine, as to 
 render it, perhaps, one of the most difficult processes in 
 this business. The best mode, in common cases, is, to pass 
 a brush over the knots, with ceruse ground in w^ater, bound 
 by a size made of parchment or glue; when that is dry, 
 paint the knots with white lead ground in oil, to which add 
 some powerful siccative, or dryer, as red lead, or litharge of 
 
C40 
 
 THE OPERATIVE MECHANIC 
 
 lead ; about oiic-fourtli part of the latter. These must be 
 laid very smoothly in the direction of the grain of the wood. 
 
 When the last coat is dry, smooth it with pumice-stone, 
 or give it the first coat of paint, prepared or diluted with 
 nut or linseed oil ; after which, when sufficiently dry, all 
 the nail- holes or other irregularities on the surface, must be 
 carefully stopped with a composition of oil and Spanish 
 white, commonly known by the name of putty. The work 
 must then be again painted with wdiite lead and oil, some- 
 what diluted with the essence of oil of turpentine, which pro- 
 cess should, if the work be intended to be left of a plain 
 white, or stone colour, be repeated not less than three or 
 four times ; and if of the latter colour, a small quantity of ivory 
 or lamp-black should be added. But if the work is to be 
 finished of any other colour, either grey, green, See. it 
 will be requisite to provide for such colour, after the third 
 operation, particularly if it is to be finished flat, or, as the 
 ])aiiiters style it, dead white, grey, fawn, &c. In order to 
 finish the work flatted or dead, which is a mode much to be 
 preferred for all superior works, not only for its ap’iear- 
 ance, but also for preserving the colour and purity of tiie 
 tint, one coat of the flatted colour, or colour mixed up 
 with a considerable quantity of turpentine, will be found 
 suflicient; although in large surfaces it will frequently be 
 requisite to give two coats of the flatting colour, to make it 
 quite complete. Indeed, on stucco it will be almost a ge- 
 neral rule. 
 
 In all the foregoing operations, it must be observed that, 
 some sort of dryer is absolutely requisite; a very general 
 and useful one is made by grinding in linseed, or, perhajis, 
 prepared oils boiled are better, about two parts of the best 
 wdiite copperas, which must be well dried with one part of 
 litharge of lead : the quantity to be added, will much de- 
 })cnd on the dryness or humidity of the atmosphere, at the 
 time of painting, as well as the local situation of the build- 
 ing. It may here be noticed, that there is a sort of cop- 
 ])eras made in England, and said to be used for some pur- 
 poses in medicine, that not only does not assist the opera- 
 tion of drying in the colours, but absolutely prevents those 
 colours drying, which would otherwise have done so in 
 the absence of this copperas. 
 
 The best dryer for all fine whites, and other delicate tints, 
 is sugar of lead, ground in nut oil, but being very active, a 
 small quantity, about the size of a walnut, will be suflicient 
 for twenty pounds of colour, when the basis is^vhitc lead. 
 
AND MACHINIST. 
 
 611 
 
 It will be always necessary to caution painters to keep their 
 utensils, brushes, &c. very clean, as the colour would other- 
 wise soon become very foul, so as to destroy the surface of 
 the work. If this should happen, the colour must be pass- 
 ed through a fine sieve, or cairvass, and the surface of the 
 work be carefully rubbed down with sand-paper, or pumice- 
 stone : the latter should be ground iuAvater, if the paint be 
 tender, or recently laid on. The above may suffice as to 
 painting on wood, either on inside or outside work, the 
 former being seldom finished otherwise than in oil : four or 
 five coats are generally sufficient. 
 
 It does not appear that painting in oil can be serviceable 
 in stucco, unless the walls have been erected a sufficient 
 time to permit the mass of brick-work to have acquired a 
 sufficient degree of dryness. When stucco is on battened 
 work, it may be painted over much sooner than when pre- 
 pared on brick. Indeed, the greatest part of the art of 
 painting stucco, so as to stand or wear well, consists in at- 
 tending to these observations, for whoever has observed the 
 expansive power of water, not only in congelation, but also 
 in evaporation, must be well aware that when it meets with 
 any foreign body, obstructing its escape, as oil painting, for 
 instance, it immediately resists it, forming a number of 
 vesicles or particles, containing an acrid lime-water, wffiich 
 forces off the layers of plaster, and frequently causes large 
 defective patches, not easily to be eradicated. 
 
 Perhaps, in general cases, where persons are building on 
 their own estates, or for themselves, two or three years are 
 not too long to suffer the stucco to remain unpainted, 
 though frequently, in speculative works, as many weeks are 
 scarcely allowed to pass. 
 
 The foregoing precautions being attended to, there can be 
 no better mode adopted for priming, or laying on the first 
 coat on stucco, than by linseed or nut-oil, boiled with dry- 
 ers, as before mentioned 5 taking care, in all cases, not to 
 lay on too much, so as to render the surface rough and irre- 
 gular, and not more than the stucco will absorb. It should 
 then be covered with three or four coats of white- lead, pre- 
 pared as described for painting on wainscotting, allow- 
 ing each coat a sufficient time to dry hard. If time will 
 permit, two or three days between each layer, will be ad- 
 vantageous. When the stucco is intended to be finished in 
 any given tint, as grey, light green, &c. it will then be pro- 
 per, about the third coat of painting, to prepare the ground 
 for such tint, by a slight advance towards it. Grey is made 
 
 2 T 
 
THli: OPKRATlVii; MECHANIC 
 
 042 
 
 with white- lead, Prussian-blue^ ivory-black, and lake; sage- 
 green, pea, and sea-greens, with white. Prussian-blue, and 
 fine yeiiows ; apricot and peach, with lake, white, and 
 Chinese vermilion ; fine yellow fawn colour with burnt 
 terra sienna, or umber and white; and olive-greens with fined 
 Prnssian-blues, and Oxfordshire ochre, 
 
 Distemper, or painting in water colours, mixed with 
 size, stucco, or plaster, which is intended to be painted in 
 oil when finished, but not being sufficiently dry to receive 
 the oil, may have a coating in Vv^ater colours, of any given 
 tint required, in order to give a more finished appearance to 
 that part of the building. Straw colours may be made with 
 French whites and ceruse, or white lead and masticot, or 
 Dutch pink. Greys, full, with some whites and refiner’s 
 vei ditcr. An inferior grey may be made wdth blue-black, 
 or bone-black and indigo. Pea-greens with French green, 
 Olympian green, &c. Fawn-colour with burnt terra de 
 sienna, or burnt umber and white, and so of any interme- 
 diate tint. The colours should all be ground very fine, and 
 mixed with whiting and a size made with parchment, or 
 some similar substance. Less than two coats will not be 
 sufficient to cover the plaster, and bear out with an uniform 
 appearance. It must be recollected, that when the stucco 
 is sufficiently dry, and it is desirable to have it painted in 
 oil, the whole of the water-colours ought to be removed, 
 which may easily be done by washing, and when quite dry, 
 proceed with it after the direction given on oil-painting in 
 stucco. 
 
 If old plastering has become disfigured by stains, or other 
 blemishes, and it be desired to have it painted in distem- 
 per, it is, in this case, advisable to give the old plastering, 
 when properly cleaned off and prepared, one coat, at least, 
 of white-lead ground in oil, and used with spirits of tur- 
 pentine, which will generally fix old stains ; and, when quite 
 dry, take water-colours very kindly. 
 
 MENSURATION OF PAINTERs’ WORK. 
 
 Painters’ w^ork is measured by the yard square, and the 
 dimensions are taken in feet, inches, and tenths. Every 
 part which the brush has passed over is measured, conse- 
 quently the dimensions must be taken with a line, that girts 
 over the mouldings, breaks, &c. All kinds of ornamental 
 work produces an extra price, according to the nature of 
 the imitations, &c. Carved work is also valued according 
 to the time taken in painting it 
 
Ax\D MACHINIST. 
 
 643 
 
 RAIL-ROADS 
 
 AND 
 
 LOCOMOTIVE ENGINES. 
 
 Amidst the various speculations of the day, perhaps none 
 have more deservedly , excited the public interest than that 
 of the numerous projected lines of rail-road for diminish- 
 ing the friction of carriages, and for propelling carriages on 
 them by either gas or steam power. 
 
 The lessening the friction, produces a consequent diminu- 
 tion in the power which otherwise would be required to 
 propel a given weight ; and therefore, is, in a commercial 
 nation, like that of the united kingdom, a subject worthy of 
 the highest consideration. 
 
 Railways were originally made of wood, and appear to 
 have been first introduced between the river Tyne and some 
 of the principal coal-pits, as early as the year 1680. The 
 scarcity of this material, and the expense of frequent re- 
 pairs, soon suggested an idea that iron might be more 
 advantageously employed. At first, flat rods of bar-iron 
 were nailed upon the original wooden rails, or, as they were 
 technically called, sleepers; which, though an expensive 
 process, was found to be a great improvement. But as the 
 wood on which these rested was liable to rot and give way, 
 these railings were soon after superseded by others made 
 entirely of iron. 
 
 These tram or rail-roads have, for a considerable length 
 of time, been much used in the colliery and mining districts ; 
 and some few have been carried from one town or manufac- 
 turing district to another. The principal of these latter in 
 England and Wales are, the Cardiff and Merthyr, 26f miles 
 longj running near the Glamorganshire canal ; the Caer- 
 marthen ; the Lexhowry, 28 miles, in the counties of Mon- 
 mouth and Brecknock ; the Surrey 26 miles ; the Swansea, 
 71 miles ; one between Gloucester and Cheltenham ; besides 
 several in the north of England. 
 
 Railways are of two kinds, arising from the disposition of 
 2t2 
 
644 
 
 THE OPERATIVE MECHANIC 
 
 tlie flaiich that is to guide the wheels of the carriage, and 
 prevent it from ruiiiiiiig off the rail. In the one, the llanch 
 is at right angles, and of one piece with the flat surface of 
 the rail : in the other, the flat surface of the rail is raised 
 above the level of the ground, and the flanch is fixed on the 
 wheel of the carriage, at right angles to the tyre, or iron 
 ])laccd on the circumference of the wheel, to strengthen it. 
 Beside these, another kind of railway has lately been intro- 
 duced by Mr. Palmer, which consists of a single rail, sup- 
 ported some height from the surface of the ground : on this, 
 two wheels confined in sufficient frame- work, are placed, 
 suspending the load equally balanced on either side. This 
 arrangement certainly seems to ensure the grand principle 
 of lessening friction, and doubtless will, in many situations, 
 be found a great improvement. 
 
 Previously to entering upon the probable advantages like- 
 ly to result from a general introduction of railways, we 
 shall give the substance of the specification of a patent, ob- 
 tained in Sept. 1816, by Messrs. Losh and Stephenson, both 
 of whom are well known to those interested in the subject. 
 
 These gentlemen preface a description of their method of 
 facilitating carriages along tram and railways, with an ob- 
 servation, that there are two kinds of railways in general 
 use ; the one consisting of bars of cast iron, generally of 
 the shape of that described by a, fig.631 , the other of the 
 shape of that described by figs. 630 and^631. That shewn at a, 
 fig. 629, is known in different situations by the denomina- 
 tion of the edge rail, round-top rail, fish-backed rail, &c. 
 That shewn at figs. 632 and 633, by the denomination of 
 the plate-rail, tram-way plate, barrow-way plate, &c. The 
 first we shall distinguish by the name of the edge railway 5 
 the second, by that of the plate railway. 
 
 In the construction of edge railways, Messrs. Losh and 
 Stephenson’s objects are, first, to fix both the ends of the 
 rails, or separate pieces, of which the ways are formed, 
 immovable, in' or upon the chairs or props by which they 
 are supported ; secondly, to place them in such a manner, 
 that the end of any one rail shall not project above or fall 
 below the correspondent end of that with which it is in con- 
 tact, or with which it is joined ; thirdly, to form the join- 
 ings of the rails, with the pedestals or props which support 
 them, in such a manner, that if these props should vary 
 from their perpendicular position in the line of the w’ay, 
 (which in other railways is often the case) the joinings of 
 the rails with each other v/onld remain as before such varia- 
 
AND MACHINIST 
 
 645 
 
 tion, and so that the rails shall bear upon the props as firm- 
 ly as before. The formation of the rails or plates of which 
 a plate railway consists, being different from the rails of 
 which the edge railways are composed, they are obliged to 
 adopt a different manner of joining them, both with each 
 other, and with the props and sleepers on which they rest. 
 But in the joining these rails or plates upon their chairs and 
 sleepers, they fix them down immovably, and in such a 
 manner that the end of one rail or plate does not project 
 above, or fall below the end of the adjoining plate, so as to 
 present an obstacle, or cause a shock to the wheels of the 
 carriages which pass over them, and they also form the 
 joinings of these rails or plates in such a manner as to pre- 
 vent the possibility of the nails, which are employed in 
 fixing them in their chairs, from starting out of their places 
 from the vibration of the plates, or from other causes. 
 
 In what relates to the locomotive engines and their car- 
 riages, which may be employed for conveying goods or 
 materials along edge railways or plate-railways, or for 
 propelling or drawing after them the carriages or waggons 
 employed for that purpose, their invention consists in sus- 
 taining the weight, or a proportion of the weight, of the 
 engine, upon pistons, movable within cylinders, into which 
 the steam or the water of the boiler is allowed to enter, in 
 order to press upon such pistons ; and which pistons are, by 
 the intervention of certain levers and connecting rods, or 
 by any other effective contrivance, made to bear upon the 
 axles of the wheels of the carriage upon which the engine 
 rests. In the formation of the wheels it is their object to 
 construct them in such a manner, and to form them of such 
 materials, as shall make them more durable and less ex- 
 pensive in the repairs than those hitherto in use. This is 
 accomplished by forming the wheels either with spokes of 
 malleable iron, and with cast iron rims, or by making the 
 wheels and spokes of cast iron, with hoops, tyres, or trods, 
 of malleable iron, and in some instances, particularly for 
 wheels of very small diameters, instead of spokes of mallea- 
 ble iron, employing plates of malleable iron, to form the 
 junction between the naves and the cast iron rims of fhe 
 wheels. 
 
 The advantages gained by this method of constructing 
 railways are, first, that the separate pieces of which they 
 consist are, ccEteris parihus, rendered by this mode of joining 
 them, capable of sustaining a much heavier pressure than 
 those which are joined in the usual way. Secondly, by this 
 
646 
 
 VIIE OPERATIVE MECHANIC 
 
 mode of joining the rails^ they remove the liability to which 
 rails joined in the usual plan, (where the end of one rail is 
 seldom in the same plane with the correspondent end of the 
 next) arc exposed, of receiving blows and shocks from the 
 carriages which move over them, and to which blows and 
 shocks the great breakage which often occurs in railways, 
 when not made of enormous weight, may generally be re- 
 ferred ; and as action and re-action are mutual and con- 
 trary, if they prevent the communication of shocks to the 
 rails, they at the same time preserve the wheels, the car- 
 riages, and engines which move over them, from the re- 
 action which is often destructive to them. As the centre of 
 gravity in a loaded coal-waggon is, from its shape, much 
 elevated, there is generally a great waste of coal from the 
 shaking of the waggons, to which that circumstance (the 
 position of the centre of gravity) makes them more liable 
 when they encounter obstacles, as they do at the junction 
 of almost every two rails on the common railways. On 
 Losh and Stephenson’s railways, the loss thus arising is, 
 if not entirely prevented, at least considerably diminished, 
 by the steady and regular motion of the waggons. The 
 usual method of fixing down the plates, of which the plate 
 railways employed in coal-mines, and there called tram 
 and rolley-ways, are formed, is by a single nail, nearly at 
 each end of each plate ; which nail passes through a hole in 
 the plate, and fixes it to a sleeper of wood. These nails, 
 from the vibration of the plate, or the motion of the sleeper, 
 or some other cause, generally very soon start up, and con- 
 sequently the plates work loose, and very frequently the 
 nails come entirely out. The delay of work, the breakage 
 of plates, wheels, &c. and the injury which the horses re- 
 ceive from the loose nails which result from the mode of 
 fixing the plate railways, are generally complained of, and 
 therefore the advantages of a plan which will remove these 
 inconveniences must be apparent. 
 
 When locomotive steam-engines are employed as the 
 jnoving or propelling power on railways, these gentlemen 
 have, from much practice, found it of the utmost impor- 
 tance, that they should move steadily, and as free as possi- 
 ble from shocks or vibrations, which have the effect of 
 deranging the working parts of the machinery, and lessening 
 their power. It is therefore to produce that steadiness of 
 motion, and to prevent the engines from receiving shocks, 
 and to preserve their equilibrium, that they employ the 
 'loaling pisloiis, which, acting on an clastic Iltiid, [)roduce 
 
AND MACHINIST. 
 
 647 
 
 the desired effect with much more accuracy than could be 
 obtained by employing the finest springs of steel to suspend 
 the engine. The wheels which are constructed on this plan 
 will be found, when compared with those already in use 
 (the weights of both being equal) to be more durable ; for 
 the arms, when made of malleable iron, being infinitely 
 less liable to be broken by shocks or concussions, than 
 those of cast iron, may be of less weight, and in fewer 
 numbers, so that the excess of weight of the extra arms of 
 the cast iron wheels may be applied on the rims of these 
 wheels, and thus add to the substance of that part which 
 alone suffers from the friction of the rails. The rims of 
 wheels thus constructed, can also be case-hardened without 
 risk of breaking, either in cooling or afterwards, which is 
 not the case when wheels are east in one piece. The ad- 
 vantage of hooping cast iron wheels with malleable iron 
 tyres or trods, is, that when such tyres or trods are worn 
 through, they can very easily be replaced at a small expense, 
 and that the tyre, whieh is not liable to break, receiving 
 the shocks from the re-action of the rails, preserves the 
 cast-iron wheel, by considerably lessening the effect of such 
 shocks on the cast metal. 
 
 As it is perhaps impossible to cast the bars or plates of 
 metal of which railways and plate- ways are composed per- 
 fectly straight, and correctly even and smooth on their sur- 
 faces, and equally difficult to fit the joints with mathema- 
 tical accuracy, the wheels of the engines and waggons will 
 always have some inequalities and obstacles to encounter. 
 From these circumstances, therefore, Messrs. Losh and 
 Stephenson are induced to employ the improvements which 
 they have made in the construction of the locomotive en- 
 gine, and in the wheels of carriages upon edge railways 
 and plate railways, constructed according to their own 
 plans 5 but it is apparent that their adoption on the rail and 
 plate-ways on the usual construction, is of still more im- 
 portance. 
 
 They therefore claim as a method of facilitating the con- 
 veyance of goods, and all manner of materials along edge 
 railways or plate railways, the use of any of the plans 
 they have described singly, as well as the whole of them 
 collectively. They have no hesitation in saying, that on a 
 railway eonstructed on their plan, and with a locomotive 
 engine and carriage-wheels on their principle, the expe- 
 dition with which goods can be conveyed with safety, will 
 be increased to nearly double the rate with which they are 
 
648 
 
 THE OPERATIVE MECHANIC 
 
 at present usually taken along railways^ and with less 
 interruption from the breakage of wheels, rails, &c. than 
 at present occurs, and with much less injury to the work- 
 ing parts of the engine. 
 
 In order that their specification may be more clearly un- 
 derstood, we have annexed a schedule of drawings. 
 
 Fig. 629 represents a longitudinal view of the locomotive engine on 
 the edge railway, a a a, are the cylinders containing the floating pistons 
 b by wliich are more fully described in the next figure. 
 
 Fig. 630 represents a cross section of Fig, 629, at the middle cylin- 
 ders a, a ; h h are the floating pistons, connected with the wrought iron 
 rods c c, the ends of which rest upon the bearing brasses of the axles of 
 the wheels d d. These pistons press equally on all the axles, and cause 
 each of the wheels to press with an equal stress upon the rails, and to act 
 upon them with an equal degree of friction, although the rails should no-t 
 all be in the same plane, for the bearing brasses have the liberty of 
 moving in a perpendicular direction in a groove or slide, and, carrying 
 the axles and wheels along with them, force the wheels to accommodate 
 themselves to the inequalities of the rail- way. 
 
 Fig. 634, is a view of the wheel, with wrought iron arms, a aaaaa 
 show how the arms are cast in the nave h h, and dropped into the mortise 
 holes c cccc c in the rim, which are dovetailed, to suit the dovetailed 
 ends of the arms d d d d d d. The arms are heated red hot previously to 
 dropping them into the holes, in order to cause them to extend sufficiently 
 for that purpose, for when cold they are too short. In doing this they 
 take advantage of that quality which iron possesses of expanding on the 
 application of heat, and of contracting again to its former dimensions on 
 cooling down to the same temperature from which it was raised ; the 
 arms, therefore, on cooling are drawn with a force sufficient to produce a 
 degree of comhination between their dovetailed ends and the mortises of 
 the rim, which prevents the possibility of their working loose ; they arc 
 afterwards keyed up ; the mortise holes are also dovetailed, from the tail 
 side of the wheel (a a, fig. 635) to the crease side (5 b, on the same 
 figure). 
 
 Fig 635, is a cross section through the centre of the wheel, with 
 wrought iron arms. 
 
 Fig. 636 is an end view of Fig. 635. 
 
 Fig. 637 represents a view of their edge railway ; shewing a rail «, 
 connected with the two adjoining rails, the ends ot which are shewn by 
 b b, and also with the props or pedestals on which they rest, d d show 
 the metal chairs, and c c the stone supports. The joints e e are made by 
 the ends of the rails being applied to each other by what is denominated 
 a half lap, and the pin or bolt g, which fixes them to each other, and to 
 the chair in which they are inserted, is made to fit exactly a hole which is 
 drilled through the chair, and both ends of the rails at such a height as to 
 allow both ends of the rails to bear on the chair, and the bearance being 
 the apex of a curve, they both bear at the same point. Thus the end of 
 one rail cannot rise above that of the adjoining one; for although the 
 chair may move on the pin in the direction of the line of the road, yet the 
 rails will still rest upon the curved surface of their bearance without 
 moving. 
 
 Fig. 638 is a cross secti«m of their edge railway through the middle ol 
 one of Uic chairs n, and across the ends ofthe two adjoining rails c d and 
 tlie pill c ,• f is Die stone support or sleeper. 
 
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AND MACHINIST. 649 
 
 Fig. 639 is a cross section of a rail a, at the centre, and sliows the car- 
 riage c behind. 
 
 Fig. 640 is a plan of the rail-way described at fig. 637, shewing tlie 
 half lap joinings of the rails c c, placed in their carriages (/ d. 
 
 Fig. 641 is a view of the cast iron wheel with the malleable iron tyre. 
 This wheel is made with curved spokes, as shewn ntaaaaaaaaaa, in 
 the figure, and with a slit or aperture in the rirn, shewn at b, into which 
 a key is inserted. The reason of this is, that on the application of the 
 hot tyre the cast metal expands unequally, and the rim is liable to be 
 cracked, and the arms drawn off, unless the first is previously slit or 
 opened, and the latter curved, which allows them to accommodate them- 
 selves to the increased diameter of the wheel ; by this formation of the 
 wheel the tyre might be forced on when cold, and keyed up afterwards. 
 
 Fig. 642 is a cross section of fig. 641, through the centre, a a show 
 the tyre, bb bh show the metal rim. This cast metal rim is dovetailed ; 
 so that when the tyre, which is dovetailed to suit it,* is put on hot, it con- 
 tracts and applies itself to the rim with a degree of adhesion which pre- 
 vents its coming otF from the motion of the wheel on the rail-way. This 
 wheel is of the form to suit an edge railway, and to make it answer for 
 a plate rail it only requires the rim to be round or flat. 
 
 Fig. 643 is an end view of fig. 641, without the malleable iron tyre. 
 
 Fig. 644 represents a view of a rolley or tram-wheel, calculated to 
 move upon a plate railway. aaaa show the malleable iron arms, 
 fastened to the projections bb b b, on the inside of the rim c c c, hy the 
 bolts d d d d. 
 
 Fig. 645 is a cross section of fig. 644, through the centre of the wheel. 
 a a show the arms, c c the rim, d d the bolts. 
 
 Fig. 646 represents a view of a rolley or tram-wheel, with a plate of 
 malleable iron « a a a, to form the junction between the nave b b and the 
 cast metal rim cccc. 
 
 Fig. 647 is across section of fig. 646. a a show the plate upon which 
 the nave 5 5 is cast, c c show the cast iron rim which is cast upon the 
 plate, the edges of which plate are previously covered with a thin coating 
 of loam and charcoal dust, or other fit substance, to prevent the too inti- 
 mate adliesion between the iron plate and metal rim, so that if tlie rim 
 should break, it can easily be taken off and replaced by casting another 
 on the plate. 
 
 Fig. 648 represents the plate railway on their plan. At the end of 
 each plate are projections aaaa, to fit into the dovetail carriage b b, and 
 at each end of each plate are projections or tenons cccc, which fall into 
 the mortise hole {d, in Figs. 649 and 6.50) in the carriage b b, and secure 
 the rail from an end motion ; and when the pin or key e is driven into its 
 place, it secures the plates from rising, thus they are fixed immovable 
 in their carriages. 
 
 Fig. 649 is a front view of fig. 648. 
 
 Fig. 650 is a plan of the carriage, in which a a show the nail holes 
 through which the nails are driven, to secure it to the sleeper. When 
 the rails are laid in this carriage, and secured by the pin or key, they 
 keep these nails from starting up by resting upon them. 
 
 Fig. 651 is a cross section of the carriage, and the end of one of the 
 plate rails. 
 
 Fig. 629* shews a rail of the common way, inclining out of the horizon- 
 tal position, as they very often do from the yielding of the props or 
 pedestals, and of course a shock is sustained by the waggons in passing 
 the joining to the next rail 
 
G50 
 
 THE OPERATiVE MECHANIC 
 
 The ease with which cast-iron can be made into any re- 
 quired shape has till very recently given to rails of that 
 material a decided superiority over those of malleable-iron. 
 But the brittleness of the former renders such rails very 
 liable to be broken^ unless, indeed, they be of such sub- 
 stance as will resist the effects of the blows or shocks to 
 which they are exposed, and which will require them to 
 be of considerably greater weight than otherwise would be 
 necessary. To obviate this, numerous experiments have 
 been made with a view to substitute malleable-iron for cast- 
 ron rails. 
 
 Rails of malleable-iron appear to have been first used at 
 Lord Carlisle’s works, at Tinclal Fell, in Cumberland, about 
 the year 1808; and though found there, and also at two 
 or three other places at which they were tried, to be a 
 saving in the first cost, and much less liable to accident, 
 they have not till very lately been much used. In fact, it 
 was not till some time after Mr. Birkinshaw, of the Bed- 
 lington Iron Works, had obtained a patent for malleable- 
 iron rails of a new and improved construction, that rails of 
 this material came into competition with the cast-iron rails. 
 
 The form of the malleable-iron rails previously to this 
 was that of a parallelopipedon ; which was liable to two 
 objections, either that the narrowness of the surfaces, when 
 compared to the breadth of the rim of the carriage wheel, 
 was so considerable as to expose both the wheel and the rail 
 to great injury from wear ; or, if the breadth of the rail 
 was increased to remove this objection, the weight of the 
 rail would make the cost amount to almost a prohibition of 
 its use. 
 
 Mr. Birkinshaw obtained his patent in October 1820 ; 
 and the improvement consisted in making the rails in the 
 form of prisms, though their sides need not of necessity be 
 flat. The upper surface, on which the wheel of the carriage 
 is to run, is slightly convex, in order to reduce the friction ; 
 and the under part, which rests on the supporting blocks, 
 chains, rests, standards, or pedestals, is mounted upon the 
 sleeper. The wedge form is proposed, because the strength 
 of the rail is always in proportion to the square of its 
 breadth and depth. Hence this form possesses all the strength 
 of a cube equal to its square, with only half the quantity of 
 metal, and consequently half the cost of the former rail. 
 Suflicient strength, however, may be still retained, and the 
 weight of metal further reduced, by forming the bars with 
 
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AND MACHINIST. 
 
 651 
 
 concave sides, which is the form of rail the paten tee decidedly 
 prefers, although the prism or wedge form, in all its varie- 
 ties, is the principle upon which his patent-right is founded. 
 
 The mode of making these wedge-formed rails of mallea- 
 ble-iron is, by passing bars of iron, when heated, through 
 rollers, having grooves or indentations cut upon their peri- 
 })heries, agreeably to the intended shape of the bar to be 
 produced. But, though the patentee recommends, and 
 adopts this mode as the most eligible means of producing 
 these rails, he claims the exclusive right of manufacturing 
 and rendering the wedge-formed bars or rails of any length, 
 for the purpose of forming or constructing rail-roads. 
 
 The advantages derived from this method of constructing 
 railways may be as follows : — 
 
 1st. The original cost of a malleable-iron railway is less 
 than a cast-iron railway of equal strength. 
 
 2dly. As the rails can be made in the lengths of 9,12,15, 
 or 18 feet each, and even longer when required, the number 
 of joints is hereby reduced ; and thus is removed, in a great 
 measure, the liability to which the short rails now in use 
 are exposed, of receiving blows and shocks from the car- 
 riages which move over them. 
 
 3dly. In order to remedy the evil arising from the rails 
 being imperfectly joined, the plan of welding the ends to- 
 gether has been adopted ; by this means making one con- 
 tinued rail the whole length of the road without any joint 
 whatever. 
 
 4thly. It hence follows, that on iron railways, the loss of 
 coals, occasioned by the jolting of the waggons at the joints 
 of the rails, and the injury done to the wheels, the car- 
 riages, and engines from the same cause, are, if not entirely 
 prevented, at least considerably diminished. 
 
 In September, 1821, Mr. Losh took out another patent 
 for further improvements in the construction of rail- 
 ways. These improvements consist, first, in fixing bars of 
 malleable iron on the upper surface of a line of cast or 
 malleable iron rails, of whatever form such rails may be, 
 in the longitudinal direction of the rails when laid, so as to 
 form an uninterrupted line the whole length of the bar, 
 which may be as long as it shall be found convenient, and 
 of the same breadth, or a little broader or narrower than 
 the upper surface of the rails to which it is fixed. Secondly, 
 in fixing, in some cases, a band or strap of malleable iron 
 to the under surface of cast-iron rails, in order that such 
 strap or band may, by its power of tension, give support to 
 
THB OPERATIVE MECHANIC 
 
 652 
 
 the cohesion of the parts of cast iron rails, and admit of its 
 being made lighter, of less expense, and less liable to 
 breakage. Thirdly, in forming a rail, by fixing two bars of 
 malleable iron on their sides or edges, and fixing them in 
 that position by bolts and studs, or any other convenient 
 method ; and in placing and fixing on their upper edges a 
 flat bar of malleable iron, or one which is slightly curved or 
 rounded at the edges to diminish friction, so that the bar 
 or plate, placed and fixed on the upper edges of the two 
 malleable iron bars, shall form the surface upon which the 
 wheels of the carriage are to revolve. 
 
 Mr. Losh states, in the specification of his patent, that 
 rail-roads are now become so general, that for the infor- 
 mation of mechanical men, or those who have the direc- 
 tion of constructing and laying them, drawings would be 
 quite superfluous ; he therefore proceeds to state the me^ 
 thods which he has found the most convenient, for forming 
 the junction of the plate or flat bar, which he applies upon 
 the surface of the body of the rail ; and also the mode by 
 which he attaches the band or strap to the lower edge of 
 the cast iron rail. 
 
 He recommends the dimensions of the bars meant to form 
 the upper surface of a railway, calculated to carry locomo- 
 tive engines of seven or eight tons, and waggons of three or 
 four tons weight each, to be fifteen or sixteen feet long, 
 two and a quarter inches broad, and half to five-eighths of 
 an inch thick. At every eighteen inches or two feet of the 
 length of this surface-plate, a tenon is firmly welded or 
 riveted ; or otherwise attached to the under side, taking 
 care in this operation to leave the upper surface of the plate 
 even as before. These tenons have holes through them in the 
 transverse direction of the bars, to take a pin or rivet of 
 from about a quarter to half an inch in diameter ; and at 
 each extremity of the plate, a tenon is fixed on by welding, 
 having previously cut off a piece of about two inches long, 
 and of half the breadth of the bar, from the opposite ends of 
 the bar or plate, and at the opposite angles, so that when 
 two bars, so prepared,‘’are brought to join at the ends, the 
 joint is what is denominated a half-lap, or scarfed joint. 
 
 If it be required to place malleable iron plates or bars on 
 cast iron rails, nothing more is necessary than to make the 
 rails with mortise holes, to receive the tenons with trans- 
 verse holes, to correspond with those in the tenons fixed on 
 the plates ; and, after placing the rails in their chairs or 
 carriages, to apply the plate to the surface of the rails, and 
 
AND MACHINIST. 
 
 653 
 
 to drop the tenons into the mortise holes, and to secure 
 them there by a pin driven tightly into and through the 
 transverse holes of the tenons and mortise holes. The 
 mortise holes are made in the rails by placing a core in the 
 mould previously to running in the metal, and lest this 
 core should weaken the rail, it is advisable to add as much 
 metal on the outside of the rail, in the form of a boss, where 
 the hole is, as will make up the deficiency. A chair is then 
 placed on a pedestal at every three or four feet distance, less 
 or more, according to the length of the cast iron rails ; and 
 each of these must be supported at its ends : these rails are 
 generally made with half-lap joints, and to rest on a curb 
 bearance. Care is taken that, where the ends of the surface- 
 plates meet to form a joint, they shall be sustained by a chair; 
 and the reason for making the joints half-lapped, or scarfed, 
 with tenons welded to these half laps is, that one pin or bolt 
 will secure both the adjoining ends of the surface-plates, and 
 of the bars of cast iron, more perfectly in the chair, than any 
 other known contrivance, when the bearance is the apex of 
 a curve. Surface-plates thus prepared with tenons, as 
 described above, may be attached and fixed to the upper 
 surface of a series of malleable iron rails placed in chairs, 
 which rails consist of flat bars (generally three or four feet 
 long, more or less, but sometimes also as long as the sur- 
 face plate), fixed on their thin edges, so as to present the 
 greatest resistance to a weight bearing upon them. For 
 this purpose, pins or rivets may be driven through the 
 transverse holes in the tenons on the surface-plate, and the 
 corresponding transverse holes made in the supporting bars ; 
 and thus may be formed a cheap and very serviceable rail- 
 way. In this case, the supporting bars should not be less 
 than two and a half inches deep, by half an inch thick, if 
 meant to carry locomotive engines. For smaller carriages, 
 the bars may be of less dimensions, in proportion to the de- 
 creased weight of the carriages. 
 
 In forming the rail, consisting of a plate of malleable 
 iron, supported by two flat bars of the same material, Mr. 
 Losh prepares the surface-plate as above with tenons, and 
 having fixed the two bars intended to support it on their 
 edges, parallel to each other, in a series of chairs, and se- 
 cured them in that position by bolts passing through them, 
 and by intervening studs, to keep them at a proper distance, 
 which is such, that the sides or edges of the surface-plate, 
 which may be a little curved or rounded, to diminish the 
 friction from the wheels passing over it, shall project about 
 
054 
 
 THE OPERATIVE MECHANK 
 
 a quarter of an inch beyond them. By these intervening 
 studs, the surface-plate is laid upon them, and the tenons 
 arc dropped in between them, and fixed by pins or bolts 
 passing in a transverse direction through holes in the bars, 
 which rwe made to correspond with holes in the tenons, 
 and thus securing them as if they were in mortise-holes. 
 The strap or band of malleable iron is fixed by Mr. Losh to 
 the under edge of the cast-iron rail, by perforating both 
 ends of the strap, near the extremities, with along hole, cal- 
 culated to pass over studs of malleable iron which are 
 fixed at each end of the rail, by being run at the time of 
 casting the rail or otherwise. The studs should be about 
 one and a half inches broad, by three- eighths of an inch 
 thick, and placed so, that when the strap has been put over 
 them in a heated state, it cannot, in contracting, slip its 
 hold ; but will, on the contrary, fix itself the closer. These 
 straps are made of malleable iron bars, about one and a 
 half inches broad, three-eighths to half an inch thick, and 
 of such length as to draw strongly against the studs and 
 bottom of the rail, when in its position. The under edge 
 of the cast iron rail to which this strap is applied being 
 curved, it will, when the strap is fixed upon the studs, by 
 an extension of its length by heat, apply itself firmly to, 
 and support every part of the lower edge of the rail, in con- 
 tracting, by parting with its heat ; and till the power of 
 tension of this strap is overcome, and it extends in length, 
 or the studs break, the rail cannot give way. 
 
 Many other methods, perhaps equally secure, may be 
 made use of to place and fix surface-plates on the surface of 
 rails ; but Mr. Losh prefers the plan pointed out, by te- 
 nons and mortise-holes, and by rivets passed through holes 
 in such tenons, and through corresponding holes in the 
 supporting bars ; because, when worn or damaged, these 
 plates can easily be taken off and replaced, without injury to 
 that part of the rail which supports them. 
 
 The principal patents obtained before the above described, 
 are those by Blenkinsop, Brunton, and Chapman ; specifi- 
 cations and drawings of which may be seen in the Reper- 
 tory of Arts. 
 
 Mr. Blenkinsop’s patent was obtained the 10th of April, 
 1811, and is for a method of fixing into the ground a 
 toothed rack, or longitudinal piece of cast iron, or other fit 
 material, having teeth, or protuberances, into which a 
 toothed or cogged wheel, connected with a locomotive car- 
 riage, plays. 
 
AND MACHINIST. 
 
 G55 
 
 Mr. Brunton’s patent was taken out the 22nd of May, 
 1813, and is for a method of propelling machines along a 
 railway by means of two or more bars or legs, which, by 
 receiving a reciprocating motion from a steam engine, act 
 against the ground like a man’s legs, when in the act of 
 walking. These bars or legs are constructed of metal or 
 wood, and of such length that, during the act of propulsion, 
 tlie angle formed by the said bars or legs and the surface of 
 the road may be such, as to afford sufficient resistance from 
 tlie materials propelled against to overcome the friction of 
 the body to be moved. This angle admits of consideral)le 
 latitude ; but will be found to answer best when between 
 50 and 70 degrees. 
 
 The reader has now been informed of the principal patents 
 that have been taken out for improvements in rail-roads. 
 The rails most in use are those of cast-iron by Losh and 
 Stephenson, and of malleable-iron by Birkinshaw.' 
 
 Previously to constructing a railway, it is necessary to 
 ascertain, as accurately as the nature of the thing will ad- 
 mit, the quantity of lading expected to traverse each way 
 upon its line. For if the weight of the carriage of merchan- 
 dize, &c. be more in the one direction than in the other, as 
 will frequently be the case in forming a line of railway from 
 a manufacturing or mining district to a town, the railway 
 must have a gentle inclination or descent ; but if the lading 
 is expected to be nearly equal in both directions, with a 
 preponderance at certain periods only, the railing must, in 
 such case, be set out in levels, or in lines nearly level, 
 and the ascents and descents made by planes inclined ac- 
 cordingly. 
 
 That the reader may see the necessity of paying due at- 
 tention to this point, we shall show the advantages that will 
 result from constructing railways with a gentle gradual 
 descent, when the carriage of the articles of trade are con- 
 siderably more in one direction than the other. 
 
 Dr. Armstrong, in his Recreations in Agriculture, ob- 
 serves, that a horse, travelling at the usual rate that w^aggons 
 move, would, wdth ease, under favourable circumstances, 
 draw 20 tons : but Mr. Fulton says, that five tons to a horse 
 is the average work on railways, descending at the rate of 
 three miles per hour ; or one ton upwards with the same 
 speed. Mr. Telford, an experienced engineer, observes, 
 that on a railway well constructed, and laid with a declivity 
 of 50 feet in a mile, one horse wall readily take down w^ag- 
 gons containing 12 to 15 tons ; and bring back the same 
 waggons with four tons in them. Mr. Joseph Wilkes, in 
 
(55G THE OPERATIVE MECHANIC 
 
 1799 stated, that a horse of the value of 20/. drew down the 
 declivity of an iron road, ^ yard, 21 car- 
 
 riages or waggons, laden with coals and timber, weighing 35 
 tons, overcoming the vis inerticv repeatedly with ease. The 
 same horse, up this declivity, drew five tons with ease. On 
 a different railway, one horse, value 30/. drew 21 waggons 
 of five cwt. each, which, with their loading of coals, 
 amounted to 43 tons eight cwt., down the declivity of l-3d 
 of an inch in a yard ; and up the same place he afterwards 
 drew seven tons ; the cwt. in all these experiments by Mr. 
 W. being 1201bs. 
 
 Though in the preceding statements there is an apparent 
 variance, the authors are not the less entitled to credit ; be- 
 cause the variations may have arisen from difference in the 
 physical strength of the animals, or in the method of con- 
 structing the railways. To make the case, how^ever, as 
 clear as possible, we shall here present our readers with 
 some observations and calculations deduced from known 
 data, which have lately appeared in a very able pamphlet, 
 entitled A Report on Rail-Roads and Locomotive Engines,’’ 
 by Mr. Charles Sylvester, civil engineer. 
 
 Mr. Sylvester, having made some judicious observations 
 on the principles of railways, and the nature of the friction 
 to be overcome, states, that, agreeably to the prineiples 
 laid down in the commencement, when a force is applied 
 equal to the friction, the smallest force above that would, 
 if continued, generate any required velocity. But it will 
 be desirable to have such a force at command, as Avill ge- 
 nerate the necessary velocity in a short time, and when that 
 has been accomplished, to reduce this force, but still to leave 
 it fully equal to the friction. If any part of the route has an 
 inclination, there ought to be an extra force at command, 
 above what would be required for a dead level. The ])lane 
 on which this experiment was made, inclined, in the direc- 
 tion of the load, about ~ of an inch to a yard. This is as 
 great, or perhaps a greater, inclination than any rail-road 
 ought to have, where loaded carriages go up and down. 
 The moving force ought, therefore, to be always greater 
 than the friction added to the force which is required to 
 overcome the inclination of the plane. The latter force 
 assists the body to go down, and equally resists it in moving 
 upwards. 
 
 On this account” says he, I have used, or supposed, a 
 moving force, which will give the velocity of 5 miles an hour, 
 ov 7^ feet per second, in the space of one minute. This will 
 be performed down the aboA^e plane by the engine making 
 
AND MACHINIST. 
 
 G57 
 
 45 strokes per minute, (the circumference of the wheel 
 being nine feet), with a pressure of 9’71bs. upon an inch, of 
 each of the two cylinders, the area of each being 63*6 square 
 inches. The weight of the engine and 16 waggons is equal 
 to 154,5601bs, or nearly 70 tons. The velocity of five miles 
 an hour being acquired after one minute, the only force to 
 keep the whole in motion, at the same rate, will be the dif- 
 ference between the gravity of the weight down the plane 
 and the friction. The friction is 9001138 ; the gravitating 
 force of the weights down the plane 5401bs ; therefore 900 
 - 540 = 3601bs. 
 
 “ If the same weight, at that speed, had to move on a dead 
 level, and acquired the same velocity in one minute as be- 
 fore, the moving force would require to be 17811bs. which 
 would require a pressure of I3-71bs. upon one inch. But 
 after the speed is obtained, it will require only 71 bs. to keep 
 it moving at the same rate. If the same load were required 
 to move up the plane, it would require a moving force of 
 23281bs. or a pressure upon every square inch of 18*31bs. 
 And this velocity would be kept up by a constant pressure 
 of 14471bs. which will be ll*31bs. upon every inch of the 
 piston. 
 
 “ In starting the engine, in the first instance, and giving 
 the required velocity, it is probable the effects will agree 
 very nearly with these calculations ; namely, 15 4,5601 bs. 
 moved at the rate of five miles an hour, with a pressure of 
 9vlbs. upon every inch of the piston. Whether the pres- 
 sure were reduced to the difference between the friction and 
 the force upon the plane, which is calculated at 2*81bs. it is 
 difficult to say, as there was no steam-gauge to indicate the 
 pressure when the engine was going.” 
 
 In table 1, at a more advanced part of the work, 
 Mr. Sylvester states, that, when the engine is required to 
 travel at the rate of nine miles per hour, the force necessary to 
 overcome the weight, I54,5601bs. will be for the first minute, 
 when the engine is travelling on a level 2890*811bs ; when 
 moving down the plane 246T611bs ; and when moving up 
 the plane 3320*01 lbs. But that, when the velocity is at- 
 tained, a force that will balance the friction is sufficient to 
 keep up the required velocity. This force is, for travelling 
 on a level, 9001bs ; for moving down the plane, 47Hbs ; and 
 for moving up the plane 13291bs. 
 
 By this, therefore, it is evident that, when the lading is 
 expected to be considerably more in one direction of the 
 line of rail-road than it is in the other, the advantage which 
 
 2 U 
 
658 
 
 THE OPERATIVE MECHANIC 
 
 will arise from making the road with a gentle slope, is very 
 gi*eat. This kind of railing is also preferable when the la- 
 ding is only equal at certain periods. For then the expense 
 of extra horses, to draw the additional vveights up the plane 
 during these periods, will fall infinitely short of the expense 
 saved by making the plane with a gentle inclination. 
 
 The necessary preliminaries being settled, the engineer 
 will obtain much greater facility, as also a diminution of ex- 
 pense, by beginning to lay down the rails on any part of the 
 intended line of road where stone, gravel, and other mate- 
 rials that are wanted, are to be most conveniently had ; as, 
 by that means, he will evade the slow and expensive mode 
 of common cartage. 
 
 The immense sums that have been invested in the hands of 
 certain companies, for the purpose of cstablisliing general 
 lines of rail- road throughout the country, have excited much 
 interest and elicited many able papers from practical men, 
 in several of the publications of the day. Amongst these, 
 perhaps those inserted in the Scotsman, an Edinburgh news- 
 paper, and in the Manchester Guardian, arc the most de- 
 serving of our notice. 
 
 The Scotsman first commences with some theoretical 
 statements, and then continues : 
 
 Having developed the theory of the motion of carriages 
 on horizontal railways, we shall have little more to do with 
 mathematical discussions, and shall now turn our attention 
 to points of a practical nature, better adapted to the taste of 
 ordinary readers. But first, we shall bring under the eye 
 again, the effect of a given quantity of power on a railway, 
 and on a canal, in a calm atmosphere—for it is only in a 
 calm atmosphere that the results can be properly compared. 
 
 We have found tliat a boat weighing with its load 15 tons, 
 and a waggon of the same lueight, the one on a canal, and the 
 other on a rail-way, would be impelled at the following rates, 
 by the following quantities of power — which we have stated 
 both in pounds and in horse power — reckoning one horse 
 power equal to 180 pounds. 
 
 Miles 
 
 Boat on a Canal, 
 power in 
 
 Horse 
 
 Waggon on a Rail-way. 
 power in Horse 
 
 per hour. 
 
 pounds. 
 
 power. 
 
 in pounds. 
 
 power. 
 
 2 
 
 33 
 
 I-5th 
 
 100 
 
 h 
 
 4 
 
 - 133 
 
 2-3ds. 
 
 102 
 
 h 
 
 6 
 
 300 
 
 H 
 
 105 
 
 h 
 
 8 
 
 r.33 
 
 3 
 
 109 
 
 h 
 
 12 
 
 1 200 
 
 7 
 
 120 
 
 2-Sds. 
 
 16 
 
 2133 
 
 12 
 
 137 
 
 i 
 
 26 
 
 3325 
 
 18 
 
 158 
 
 1 
 
AND MACHINIST. 
 
 659 
 
 We have not taken into account the time lost in over- 
 coming the inertia of the waggon wiiere a small power is 
 applied, because, in point of fact, the casual resistance of 
 the wind would render it necessary to provide double or 
 triple the power above stated. But if necessary, the time 
 lost by the slow motion at first might be saved. Suppose 
 there are a certain number of places where the steam-coach 
 or waggon was to stop, to take in or put out passengers or 
 goods; and farther, that the waggon, by travelling a few 
 miles, has acquired an uniform velocity of 20 miles an 
 hour. Then, if it is made to ascend an inclined plane of 10 
 feet perpendicular height, this velocity will be extinguished, 
 and the vehicle will stop at the head of the plane. When 
 it is to proceed again on its journey its descent along an in- 
 clined plane of the same height on the other side, will enable 
 it to recommence its career in a few seconds with the full 
 velocity of 20 miles an hour. By raised platforms of this 
 kind, at the two extremities of the journey, and at the in- 
 termediate stages, the velocity thus generated, might be 
 treasured up for permanent use. The platforms should be 
 of different heights, corresponding to the various velocities 
 of the vehicles plying on the railway. But, in point of 
 fact, the terminal velocity is attained so soon from a state of 
 rest, that this contrivance would probably be found un- 
 necessary. 
 
 Where locks or lifts occur. The 'stationary steam-engine 
 should drag up the vehicle (supposing it to be along an in- 
 clined plane), not simply from the one level to the other, 
 but to a platform some feet above the higher level, that the 
 vehicle, by its descent, might recover the lost velocity. It is 
 plain, however, that when the difference of level did not 
 exceed eight or ten feet, the momentum of the vehicle 
 would carry it up without any assistance from a stationary 
 engine, and with merely a small temporary loss of velocity. 
 
 Some persons imagine erroneously that teethed wheels 
 and rackwork would be necessary where the railway was 
 not perfectly level. But the friction of iron on iron being 
 25 per cent, of the weight, if the whole load was upon the 
 w’heels to which the moving power was ap()lied, and if the 
 quantity of power was sufficient, the waggon would ascend 
 without slipping though the plane rose one foot in four — 
 while even cart roads scarcely ever rise more than one foot 
 in 18 or 20. If four-fifths of the load, however, were placed 
 on separate cars, and only one-tenth of the whole pressure, 
 for instance, was upon the axle to which the moving force 
 
660 
 
 THE OrERATIVE MECHANIC 
 
 was applied, the power of ascent by friction would only be 
 one-tenth of one foot in four, or one foot in forty. 
 
 The steam engine, as we commonly see it, is so bulky, 
 and with the addition of its fuel and supply of water, so 
 ponderous, as to create an impression on a first view, that 
 its w’hole power would scarcely, under the most favourable 
 circumstances, transport its own weight. The steam-boat, 
 however, which cuts its way through the ocean, in defiance 
 of tide and tempest, shews that this is a mistake. For all 
 velocities above four miles an hour, the locomotive engine 
 will be found superior to the steam-boat ; that is to say, it 
 will afford a greater amount of free power, above what is re- 
 quired to move its own weight. 
 
 i. We have seen various statements respecting the loco- 
 motive engine, few of them so detailed as could be desired — 
 from which we subjoin the following particulars : 
 
 Trevithick and Vivian’s high pressure locomotive en- 
 gine, with a cylinder of eight inches diameter, and a pres- 
 sure of 65 pounds per square inch (apparently about eight 
 horse power), drew carriages containing ten and a half tons 
 of iron, at five and a half miles per hour, for a distance of 
 nine miles. (Stuart’s History of Steam Engine, p. 164.) 
 Whether on a road or railway is not mentioned. 
 
 We find it stated in a Liverpool paper, as the result of 
 inquiries made respecting the locomotive engines, that one 
 of these, of ten horse power, conveys fifty tons of goods at 
 the rate of six miles an hour on a level railway. But was 
 the road an edge or tram road ? 
 
 Mr. Blenkinsop states, in replies to queries put by Sir 
 John Sinclair, that his patent locomotive engine, with two 
 eight-inch cylinders, weighs five tons, consumes 2-3d 
 cvvt. of coal, and fifty gallons of water per hour, draws 27 
 waggons weighing 94 tons on a dead level, at three and a 
 half miles per hour, or 15 tons up an ascent of two inches 
 in the yard ; when ‘ lightly loaded’ travels 10 miles an hour, 
 does the work of 16 horses in 12 hours, and costs 4001. 
 Another person says, that the weight of this engine with its 
 water and coals is six tons, and that it draws 40 or 50 tons 
 (waggons included) at four miles an hour on a level rail- 
 way. (Repertory of Arts, 1818, p. 19-21 This seems to 
 have been a high pressure engine of about eight or ten 
 horse power. But we are not informed what sort of rail- 
 way it worked on, how long its journies were, or what is 
 meant by ‘ lightly loaded.’ 
 
 We shall take for granted then that an eight-horse 
 
AND MACHINIST. 
 
 661 
 
 power high pressure engine, with its charge of water and 
 coal, and with the car which bears it, weighs six tons, and 
 that it requires an additional supply of 100 weight of coal, 
 and 400 weight of water for each hour it works. This is 
 very consistent with other ascertained facts. We find, for 
 instance, in the parliamentary report on steam navigation, 
 that the low pressure engines used in vessels, which are 
 made twice as strong as stationary engines, weigh about one 
 ton and one-fifth for each horse power, including their 
 charge of water and coal. Now the high-pressure engines 
 want the condensing apparatus which must diminish the 
 weight probably by one-fourth part. The estimate for coal 
 we have increased one-half, because we think it rather below 
 the truth. It is only about nine pounds per hour for each 
 horse power, while Mr. Watt allows twelve pounds for his 
 low pressure engines. 
 
 It follows, therefore, that an eight-horse power locomo- 
 tive engine, with coal and water for eight hours, would 
 weigh eight tons. Hence, bulky and ponderous as the 
 steam-engine appears, we find ,that a locomotive engine, 
 weighing eight tons, moves 50 tons beside itself, (taking the 
 more moderate estimate,) that is, it consumes only one- 
 seventh part of the power it creates, when travelling at four 
 miles an hour; or the free power applicable to other pur-' 
 poses, is seven-eighths of the whole. This is the result of an 
 early experiment, made probably upon a rail-road not of the 
 best kind, and with vehicles much less perfect than they 
 may yet be rendered. Though it falls much under the effect 
 calculated theoretically, it does not strike us as being incon- 
 sistent with the truth of the principles on which the calcu- 
 lation VA^as founded. 
 
 The high pressure engine, on account of its smaller 
 weight and bulk, is evidently best adapted for railways ; and 
 it can be used with perfect safety, because it may be easily 
 placed in a car by itself, a few feet before the vehicle in 
 which the passengers are. The vehicle itself, by its regular 
 and steady motion on the railway, would answer the pur- 
 pose of 2 i fly-wheel in the most perfect manner. The en- 
 gine might run upon six wheels, which should be locked 
 together by teeth pinions, that the tendency to slip might be 
 resisted by the friction of the whole mass of eight tons. 
 
 The best form of a steam coach for the conveyance of 
 passengers would probably be the following : — A gallery 
 seven feet high, eight wide, and 100 feet in length, formed 
 into 10 separate galleries 10 feet long each, connected with 
 
662 
 
 THE OTERATIVE MECHANIC 
 
 each other by joints working horizontally, to allow the train 
 to bend where the road turned. A narrow covered foot- 
 way, suspended on the outside over the wheels on one side, 
 would serve as a common means of communication for the 
 whole. On the other side might be outside seats, to be used 
 in fine weather. The top, surrounded with a rail, might 
 also be a sitting place of promenade, like the deck of a 
 track boat. Two of the 10 rooms might be set apart for 
 cooking, stores, and various accommodations; the other 
 eight would lodge iOO passengers, whose weight, with that 
 of their luggage, might be 12 tons. The coach itself might 
 be 12 tons more ; and that of the locomotive machine, eight 
 tons, added to these, would make the whole 32 tons. Each 
 of the short galleries might have four wheels ; but to lessen 
 the friction, the two first wheels only should be grooved, the 
 two last cylindrical, and three or four times as broad as the 
 thickness of the rail. The conveyance of goods would be 
 effected by a train of small waggons loosely attached to each 
 other. 
 
 It will be observed from the table we have given above, 
 that it would require seven horse power to impel a steam- 
 boat weighing 15 tons at 12 miles an hour. This gives a 
 load of two tons so moved ; however, tlie engine, if a low 
 pressure one, with water and eight hours’ coals, would weigh 
 nearly 10 tons, and the vessel would weigh at least five ; so 
 that the whole power of the engine would be expended in 
 impelling itself and the ship containing it, at the supposed 
 rate, and no free power would remain for freight. Facts 
 show that the resistance is actually rather greater in 
 water than theory in this case represents it. We have cal- 
 culated from data furnished by the Parliamentary Report on 
 steam navigation, that the entire burden on the engine in 
 vessels going only eight or nine miles an hour in calm 
 weather, rarely exceeds three tons for each horse power, 
 while, according to the table, it should be five tons. Indeed, 
 in our common steam-vessels for passengers, going eight or 
 nine miles an hour, the ship and engine may be considered 
 as constituting the whole burden. For 50 passengers, 
 weighing perhaps with their luggage six or eight tons, placed 
 on board a ship weighing, with her engine of 60 or JO horse 
 power, a hundred and fifty or hundred and eighty tons, form 
 but an addition of one- twentieth or one- thirtieth to the 
 mass — a quantity of no importance in a practical point of 
 view. If we convert the steam-engine power into real horse 
 power, and figure to ourselves 100 horses employed to 
 
AND MACHINIST. 
 
 663 
 
 draw 50 persons, we see what an enormous waste of power 
 there is in the mode of conveyance. We may remark fur- 
 ther, that the tenor of the evidence given before the Par- 
 liamentary Committee rendersit extremely doubtful, whether 
 any vessel could be constructed, that would bear an engine 
 capable of impelling her at the rate of two miles an hour, 
 without the help of wind or tide. 
 
 When the steam coach is brought fully into use, practice 
 will teach us many things respecting it, of which theory 
 leaves us ignorant. With the facilities of rapid motion 
 which it will afford, however, we think we are not too san- 
 guine, in expecting to see the present extreme rate of tra- 
 velling doubled.’’ 
 
 This practicability of conveying individuals or merchan- 
 dize at the speed required in the present improved state of 
 our internal intercourse-with the different parts of the king- 
 dom, has created much doubt and discussion with many able 
 and practical mechanics. The question seems to resolve 
 itself thus. Do the friction incurred by any moving body, 
 laying aside the resistance of the atmosphere, increase in 
 proportion to its velocity ? 
 
 Without going into any diffuse or theoretical argument on 
 this point, we shall merely cite that by the results of actual 
 experiments instituted by Vince and Coulomb, it appears 
 that friction does not increase in proportion to the velocity. 
 
 By experiments made also by Stephenson and Wood, 
 it appears that the force required to keep a given weight in 
 motion does not vary with the velocity : thus, a force of 
 141bs. was found to overcome friction, and keep in motion 
 an empty coal waggon, weighing 23*25 cwt. on a rail- road ; 
 and that on doubling the velocity, no more force was re- 
 quired. Further also it appears, that on increasing the 
 weight, or load, the power required to overcome the fric- 
 tion, and keep the waggon in motion, did not increase in si- 
 milar proportion, but up to 76*25 cwt. was about one-four- 
 teenth less. 
 
 Notwithstanding the simple and satisfactory manner by 
 which the experiments that led to these results were con- 
 ducted, the fact has been still much doubted. We cannot 
 therefore do better than to extract from the Manchester 
 Guardian the following article, which contains an account 
 of experiments, with most conclusive results, made by that 
 able mechanic, Mr. Roberts of Manchester : — 
 
 The object of the papers on rail-roads which appeared 
 in the Scotsman, was, in a great measure, to shew the prac- 
 
664 
 
 THE OPERATIVE MECHANIC 
 
 ticability of transporting commodities upon rail-roads at a 
 very considerable speed ; and (with some fallacies, which 
 we shall endeavour to point out) they contain a great deal 
 of valuable information, on the relative merits of highways, 
 canals, and rail-roads. The principal point, however, and 
 the one to which we shall confine our observations, is an 
 enunciation of the law’s wdiich regulate the friction of rolling 
 and sliding bodies, as deduced from the experiments of 
 Vince and Coulomb. With a view to the illustration of 
 this part of the subject, some very important and conclu- 
 sive experiments have recently been made in this town, to 
 wdiich we shall by and by have occasion to refer at some 
 length ; but before doing so, we must make a few observa- 
 tions on the rule laid down by the Scotsman, and the mis- 
 conceptions w’hich appear to have prevailed respecting it, 
 both in that journal and in other quarters. 
 
 After comparing the resistance experienced by a boat 
 moving through the water, with the friction which retards 
 the progress of a w^aggon on a rail- road, and stating that 
 they are governed by different law’s, the Scotsman notices 
 the conclusions established by the experiments of Vince and 
 Coulomb ; the most important of which is, that the friction 
 of rolling and sliding bodies is the same for all velocities. 
 The WT’iter then observes 
 
 ^ It is wdth this last law only that w’e have to do at pre- 
 sent ; and it is remarkable that the extraordinary results to 
 which it leads, have been, as far as w’e know, entirely over- 
 looked by writers on roads and railways. These results, 
 indeed, have an appearance so paradoxical, that they will 
 shock the faith of practical men, though the principle from 
 which they flow is admitted without question by all scienti- 
 fic mechanicians. 
 
 ^ First. It flow\s from this law, that (abstracting the re- 
 sistance of the air,) if a car w ere set in motion on a level 
 railway, with a constant force greater in any degree than 
 is required to overcome its friction, the car would proceed 
 with a motion continually accelerated, like a falling body 
 acted upon by the force of gravitation ; and how’ever small 
 the original velocity might be, it would in time increase 
 beyond any assignable limit. It is only the resistance of the 
 air (increasing as the space of the velocity) that prevents this 
 indefinite acceleration, and ultimately renders the motion 
 uniform. 
 
 ^ Secondly. Setting aside again, the resistance of the air 
 (the effects of w’hich we shall estimate by and by,) the very 
 
AND MACHINIST^ 
 
 665 
 
 same amount of constant force which impels a car on a rail- 
 way at two miles an hour, would impel it at ten or twenty 
 miles an hour, if an extra force were employed at first to 
 overcome the inertia of the car, and generate the required 
 velocity. Startling as this proposition may appear, it is an 
 indisputable and necessary consequence of the lav’s of 
 friction. 
 
 ^ Now it would at all times be easy, as we shall afterwards 
 show, to convert this accelerated motion into a uniform 
 of any determinate velocity ; and from the nature of the re- 
 sistance, a high velocity would cost almost as little, and be 
 as readily obtained as a low one. For all velocities, there- 
 fore, above four or five miles an hour, rail- ways will afford 
 facilities for communication prodigiously superior to canals, 
 or arms of the sea.’ 
 
 Now we are perfectly satisfied, both by the experiments 
 of Vince and Coulomb, and those more recent and conclu- 
 sive experiments, to which we have already alluded, that 
 the rule laid down here is correct ; but the writer ought to 
 have guarded against the misconception to which his last 
 paragraph is liable. When he says that a high velocity 
 would cost almost as little as a low one, he should have 
 said that it would cost as little per mile, or as little over any 
 given space : for it cannot be his meaning, that a carriage 
 can be kept moving for an honr, or for any given time, at a 
 high veloeity, with as little expenditure of power, as at a low 
 velocity. Yet this he has been generally understood to 
 mean, and a great deal has been written and said with a 
 view to prove that he was mistaken ; when in fact he was 
 only misunderstood. In a subsequent article, however, 
 the author appears, in some degree, to have fallen into the 
 same error into which he has led other persons. He says : 
 
 ‘ Every body knows that the rate of stage coach travel- 
 ing in this country has increased within the last twenty-five 
 years, from six or seven miles an hour to eight or nine, and 
 this, too, before roads were YFAdamized, and with much 
 less injury to the horses than was anticipated. Supposing 
 that a coach-horse could run fourteen miles unloaded, with 
 the. same muscular exertion which carries forward the 
 stage-coach at eight or nine miles, then professor Leslie’s 
 formula becomes 3-4ths (14 v)2. Each horse would, of 
 coui*se, draw with a force of 481bs. at six miles, and of 
 271bs. at eight miles an hour. But if the friction increased 
 in the ratio of the velocity, the load upon each horse w’ould 
 increase from 481 bs. to 601 bs., when the speed increased 
 
665 
 
 THE OPERATIVE MECHANIC 
 
 from six to eight miles an hour : and as the horse exerting 
 the same strength, would only pull with a force of 271bs., 
 he would thus have more than double work to do, which is 
 plainly impossible. But admit that the friction is equal in 
 equal times ; then, since the time is diminished l-4th by 
 increasing the speed from six to eight miles an hour, the 
 horses have actually 4- 5ths less to do ; the load upon each is 
 reduced from 481bs. to 36, and the horse would have to in- 
 crease its exertion only 1 -3rd, that is, from 271bs. to 36 . 
 The facts, we believe, will be found strictly consistent with 
 this hypothesis, and decidedly at variance with the other. 
 However strange it may sound, then, to common observers, 
 it is practically true, that a smaller absolute amount of force 
 will drag a coach over the same space in three hours than in 
 four, and in one than in two.’ 
 
 This paragraph seems to us to contain a^ very obvious 
 fallacy. If the speed be increased from six miles an hour to 
 eight, the horses have by no means l-4th less work to do, 
 supposing the friction a constant quantity, and the traction 
 consequently the same. It is true that they exert this 
 power for a shorter time, but it is over the same distance. 
 Supposing the power of traction necessary to overcome the 
 friction is lOOOibs., then that power must be extended over 
 every yard of the distance, whether the carriage moves at 
 six or eight miles an hour : and it is by the distance, not 
 the time, that the power must be measured. That this 
 must be the case, will be obvious if the experiment be put 
 in another shape. Suppose a perfectly horizontal railway, 
 a mile long, with a perpendicular descent of a mile at one 
 end of it, as represented in fig. 652. 
 
 Suppose a waggon placed on this railway at A, at- 
 tached to a rope passing over a pulley at B, and loaded at 
 that point with a weight exactly sufficient to overcome the 
 friction, then, if the resistance of the air is nothing, and 
 the rope be without weight, it follows, from the rule laid 
 down, that if the waggon is set in motion at any given 
 speed, it will continue to move at that rate, until it reaches 
 the point B and the weight falls to C. But whether the 
 waggon passes over the railway in an hour or in three 
 minutes, it is obvious that the same weight will descend 
 through the same space, and that consequently, the same 
 amount of power will be expended. It is, perhaps, neces- 
 s^y to observe here, that if the weight is only just suffi- 
 cient to overcome the friction, there will (as is proved by 
 
AND MACHINIST. 667 
 
 the experiments of Mr. Vince) be no acceleration of motion 
 on the principle of falling bodies. 
 
 However^ though a carriage cannot, as we think we 
 have shewn, be moved ten miles in one hour, with a similar 
 expenditure of power than in two, it is very interesting to 
 know that it can be moved with the same expenditure, 
 (excepting the resistance of the air.) In many cases dis- 
 patch is of so much consequence, that the elucidation and 
 application of this rule will probably lead to very important 
 results. Many persons, however, are very sceptical on this 
 subject, and contend that the experiments of Vince and 
 Coulomb do not authorise any such conclusions as have 
 been drawn from them. It has been asked, if the same 
 constant force will move a carriage as well at a high as at a 
 low velocity, why we do not see something like this in prac- 
 tice ; why a carriage moved by a steam-engine instead of 
 acquiring, as it proceeds, a high degree of velocity, moves 
 on at one uniform rate after it has overcome the vis inerticc 
 at the commencement of its journey ? We think the rea- 
 son is very obvious. A locomotive steam-engine does not 
 exert the same constant force on the peripheries of the 
 wheels of the carriage, when it moves at different veloci- 
 ties. For instance, suppose the piston of an engine to move 
 220 feet in a minute, and to impel the peripheries of the 
 travelling wheels at a velocity of t^vo miles, and with a 
 force just sufficient to overcome the friction, how can the 
 speed be augmented without increasing the power of the 
 engine ? If the diameter of the wheels be increased with 
 the view of increasing the speed, the force with which they 
 are impelled will be diminished in the same proportion ; 
 and the engine will stop, unless the pressure is increased. 
 To increase that, of course, wdll be to augment the power. 
 As it is obvious, therefore, that a steam-engine cannot ex- 
 ert the same force at different velocities, some other means 
 must be devised for putting to the test of experiment the 
 rule laid down in the Scotsman, 
 
 We now come to the most important and interesting 
 part of this article. As none of the experiments of Vince or 
 Coulomb (so far as we have seen or heard them detailed) 
 were made with bodies resembling railway waggons, 
 either in form, or in the nature of their motion, the cor- 
 rectness of the conclusions deduced from them with respect 
 to such carriages, was doubted by many persons of consi- 
 derable scientific attainments. It became desirable, there- 
 fore, that other experiments should be tried, with carriages 
 
THE OPERATIVE MECHANIC 
 
 668 
 
 upon railways, which, of course, would be much more 
 satisfactory. This, however, it did not, at first sight, ap- 
 pear very easy to accomplish in a satisfactory manner ; but 
 Mr. Roberts, of this town, recently devised a mode of de- 
 termining the point, which appears to us wholly unobjec- 
 tionable, and which exhibits, in a high degree, the simpli- 
 city and facility of execution, by which that gentleman’s 
 inventions are so eminently distinguished. It was very 
 difficult to devise means for measuring accurately the fric- 
 tion of a carriage moving over a railway ; but it occurred 
 to Mr. Roberts, that the difficulty would be obviated if the 
 railway were made to move under the carriage. When this 
 idea once presented itself, it was easy to reduce it to prac- 
 tice. Mr. Roberts therefore constructed an apparatus, of 
 which fig. 654 will give a pretty correct notion. 
 
 A is a small wag-^on Mith four cast iron wheels, placed on the peri- 
 phery of a cast iron drum B, three feet in diameter, and six inches broad, 
 (which acts as the rail-road.) This drum is fastened on the same shaft as 
 the pulley C, which is driven at different speeds by a strap from another 
 pulley. The wagg’on is attached by a wire to one of Marriot’s patent 
 weighing' machines D, for the purpose of measuring the friction, and the 
 board G, prevents the current of air, occasioned by the motion of the 
 drum, from acting upon the carriage. Now if the drum be driven with 
 any given velocity, say four miles an hour, in the direction indicated by 
 the mark E, and the waggon held in its place by the wire which attaches 
 it to the index, it is perfectly obvious that the wheels will revolve on the 
 drum in precisely the same manner as if the waggon moved forward on a 
 horizontal road ; and the friction will also be the same, except, perhaps, a 
 small addition occasioned by the curvature of the drum, but which will 
 not affect the relative frictions of different speeds. As the waggon is sta- 
 tionary, the resistance of the air will be entirely got rid of ; and the index 
 of the machine will indicate the precise amount of traction necessary to 
 overcome the friction. Of course, in making the experiment, it will be 
 necessary to keep the centre of the waggon exactly over the axis of the 
 drum ; for if it were permitted to go beyond the centre, a part of the 
 weight would be added to the friction ; if, on the contrary, it was brought 
 nearer the index, a part of the weight would act against the friction, and 
 diminish the apparent quantity. The tempering screw F, is therefore 
 added to keep the waggon in its proper situation, in whatever way the 
 spring of the weighing machine may be acted upon by the friction. 
 
 This simple apparatus having been constructed, a number of experi- 
 ments were made, chiefly with a view to determine whether the friction 
 were the same at different velocities. The waggon was loaded with fifty 
 pounds, (including its own weight) and the drum was driven at different 
 velocities, varying from two to twenty-four miles an hour on the periphe- 
 ry : but in every case, the friction, as indicated by the weighing machine, 
 was precisely the same. No increase of speed affected the index at all, 
 but on increasing the weight, it immediately shewed a corresponding in- 
 crease of friction. 
 
 We consider these experiments as perfectly conclusive 
 
663 
 
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AND MACHINIST. 
 
 669 
 
 of the fact, that the friction on a railway is the same for all 
 velocities ; and that a carriage may be propelled twenty miles 
 in one hour, with the same amount of force which would 
 be necessary to drive it twenty miles in ten hours, provided 
 the resistance of the atmosphere was out of the question ; 
 and, if the carriage was properly constructed, that would 
 not amount to much. In other words, goods may be con- 
 veyed from Manchester to Liverpool, on a rail-road, with 
 very nearly the same expenditure of steam, whether they are 
 carried two miles, or four miles, or twenty miles an hour. A 
 steam engine, which will propel twenty tons at four miles 
 an hour, will, with the same expense of coals, propel ten 
 tons at eight miles an hour ; so that, with the smaller load, 
 it might make a journey to Liverpool and back, in the same 
 time which would be occupied in going thither with the 
 larger load Or, to put the matter in another shape : sup- 
 pose a four-horse engine will convey forty tons to Liverpool 
 in eight hours, an eight horse engine will convey the same 
 weight thither in four hours. There will be the same ex- 
 penditure of steam in both cases, but, in the latter, a 
 saving of half the time ; a saving which, we need not add, 
 .will frequently be of immense importance.” 
 
 These practical results are very satisfactory," as the hope 
 of propelling carriages at a suitable speed, for the more ra- 
 pid dispatch of business, and conveyance of passengers, is 
 thereby placed almost beyond a doubt. 
 
 We ought to notice here, the striking difference in the 
 force requisite to give rapid motion on a rail-road to that on 
 a canal or navigable river. These latter are governed by a 
 totally different law, as the resistance, or head of water on 
 the bows of the boat, increase as the squares of its velocity ; 
 consequently it will require four times the power to double 
 the speed. But, on the other hand, it must be admitted, 
 that in all speeds under three miles per hour, the canal has 
 a decided advantage, as the force increases as the speed di- 
 minishes. 
 
 With respect to the horse, it is well known, that his 
 power decreases as his speed increases ; and that when he is 
 travelling at his greatest speed, which, with a weight, sel- 
 dom exceeds 13 miles per hour, he is able to exert little or 
 no strength. We, therefore, take it for granted, that in the 
 present improved state of our manufactures, artificial pow- 
 er of some description must be resorted to, and whatever 
 experience may prove to be the most economical, the ap- 
 plication of that power is the most important part of the 
 
THE OPERATIVE MECHANIC 
 
 6/0 
 
 subject now under consideration. On this point, the data 
 with which we are furnished is so veiy limited, as scarcely 
 to render it possible to form any decisive opinion. 
 
 The engines which have been some time at work at Mr. 
 Brandley’s collieries, near Leeds, have a cogged wheel, 
 playing in a rack, which is laid as one of the rails of the 
 road ; and those at Hetton colliery are much on the same 
 principle. This plan is objectionable, because the whole 
 weight of the engine, which, on the most improved con- 
 struction, is not less than eight tons, is on the wheel, so 
 that any obstacle on the rail, must of necessity shake the 
 whole machinery. To obviate this, Mr. Gordon has con- 
 trived, and taken out a patent for a locomotive carriage with 
 the engine on springs, which imparts the motion without 
 any connexion with the wheels or axle-tree, and there are 
 various other plans in progress for the same object. But let 
 this be effected as it may, the great weight of the engine, 
 which is by far the greatest objection, is not obviated. And, 
 indeed, this appears to us only possible to be accomplished, by 
 either diminishing the weight of the engine, as proposed by 
 the application of Mr. Brown’s pneumatic, or vacuum en- 
 gine, or taking the engine entirely from the carriage, and 
 employing stationary engines, at suitable distances, to tow 
 or draw the carriages in regular succession. This last mode 
 has been applied to practice in the vicinity of Newcastle, 
 by Mr. Thompson ; and the results may be seen in some 
 very able observations annexed to the specification of his 
 patent, and inserted in the Repertory of Arts, for March, 
 1822 . 
 
 His method consists in dividing the line of Rail- road into 
 any number of stages, at suitable distances apart. At the 
 end of each stage an engine is erected for the purpose of 
 drawing the carriages from the next stage, or engine, on 
 either side, towards itself. This is effected by means of 
 ropes, which, previously to commencing operation, are 
 taken from each respective engine to the engine immediately 
 before it by horses ; but after the work has commenced, by 
 being hooked at the end of the advancing or returning 
 carriages. 
 
 Ill forming lines of rail- road ujion this system, that is, where 
 stationary engines are to be employed, it is not necessary 
 that they incline in the direction of the loads, or be made 
 perfectly level. For in engines of this description there is 
 no occasion to pay that particular attention to the weight of 
 the boiler and a])purtenances, as is the case in engines 
 
AND MACHINIST. 
 
 671 
 
 which have a locomotive principle. Indeed trifling inequali- 
 ties of surface, which would be a material objection in the 
 application of locomotive carriages, are, in the lines of road 
 where stationary engines are employed, quite unheeded. 
 
 As many roads are traversed by night as well as by day, 
 it becomes necessary that a signal should be given from one 
 engine to the other as soon as the carriages have arrived and 
 are hooked to its respective ropes, that the engine tender 
 may not be at a loss when to throw his machinery into 
 geer. For this purpose, Mr. Thompson recommends that 
 the door of the fire-place of the boiler, or other strong light, 
 be placed towards the engines on each side, so that, by 
 opening it on that side which faces the engine, to whose 
 ropes the carriages just arrived have been attached, the en- 
 gineer may adopt such measures as will effect the desired 
 purpose. 
 
 It is true, locomotive engines were not at that period so 
 well understood as at present ; but it appears to us that this 
 point still remains in a very undecided state, and that from 
 the even now limited experience in propelling carriages on 
 railways, at a speed any thing like that of common 
 carriages, it is very difficult to hazard an opinion. From 
 the data, however, that can be collected, we certainly in- 
 cline to stationary engines, as the most mechanical and 
 economical application of the requisite power. 
 
 As to the degree of danger which travellers may be ex- 
 posed to by locomotive engines, it cannot, under a 
 proper management, exceed that of a steam-boat, or a 
 factory, where power is operating. It is true, that as the 
 weight of the engine is of great consideration, condensing 
 engines (if steam be the force employed,) are quite inappli- 
 cable, and what are generally called high pressures must be 
 introduced. But though all engines which do not condense 
 their steam, and act only by the pressure, or elastic force, 
 are called high pressure engines, there is no necessity what- 
 ever to go to dangerous heats, and with either wrought- 
 iron or copper boilers and valves, placed out of the reach 
 of the operative engineer, or engine tender, may certainly 
 be worked at 45 or 53ibs. pressure, with as much safety as 
 at 201bs. in condensing engines. Indeed, on investigating 
 the cause of steam explosions, they will be found to have 
 rarely oceurred but from the grossest ignorance and neglect. 
 
 Such of our readers who are desirous to have farther in- 
 formation on this interesting subject, we must refer to a 
 very able report on rail-roads, by Mr. Charles Sylvester, 
 
772 THE OPERATIVE MECHANIC, &C. 
 
 to the paper alluded to by Mr. Thompson, in the Repertory 
 of Arts, for March, 1822, to a work which will shortly 
 issue from the Press, by Mr. N. Wood of the Killingworth 
 Colliery, of whose experiments, in conjunction with Mr. 
 Sylvester, we have already had occasion to speak, and to 
 Observations on a General Iron Railway, by Mr, Gray. 
 
APPENDIX 
 
 GEOMETRY. 
 
 Geometry is that branch of mathematics which treats of the de- 
 scription and properties of magnitudes in general. 
 
 Definitions or Explanation of Terms. 
 
 1. A point has neither length, breadth, nor thickness. From this 
 definition it may easily be understood that a mathematical point can- 
 not be seen nor felt ; it can only be imagined. What is commonly 
 called a point, as a small dot made w'ith a pencil or pen, or the point 
 of a needle, is not in reality a mathematical point ; for however small 
 such a dot may be, yet if it be examined with a magnifying glass, it 
 will be found to be an irregular spot, of a very sensible length and 
 breadth ; and our not being able to measure its dimensions with 
 the naked eye, arises only from its smallness. The same reasoning 
 may be applied to every thing that is usually called a point ^ even 
 the point of the finest needle appears like that of a poker when ex- 
 amined with the microscope. 
 
 2. A line is length, without breadth or thickness. What was said 
 above of a point, is also applicable to the definition of a line. What 
 is drawn upon paper with a pencil or pen, is not in fact a line, but 
 the representation of a line. For however fine you may make these 
 representations, they will still have some breadth. But by the 
 definition, a line has no breadth whatever, yet it is impossible to 
 draw any thing so fine as to have no breadth. A line therefore, can 
 only be imagined. The ends of a line are points. . 
 
 3. A right line is what is commonly called a straight line, or that 
 tends every where the same way. 
 
 4. A curveis a line which continually clianges its direction between 
 its extreme points. 
 
 5. Parallel lines are such as always keep at the same distance 
 from each other, and which, if prolonged ever so far, would never 
 meet. Fig. 1. 
 
 6. An angle is the inclination or opening of two lines meeting in 
 a point. Fig. 2. 
 
 7. The lines AB, and BC, which form the angle, are called the 
 legs or sides j and the point B where they meet, is called the vertex 
 of the angle, or the angular point. An angle is sometimes express- 
 ed by a letter placed at the vertex, as the angle B, Fig. 2 j but most 
 commonly by three letters, observing to place in the middle the letter 
 at the vertex, and the other two at tho end of each leg, as the 
 angle ABC. 
 
APPENDIX. 
 
 G74 
 
 8 . When one line stands upon another, so as not to lean more to 
 one side than to another, both the angles which it makes with the 
 other are called rig/i/ as the angles ABC and A BD, Fig. 3, 
 and all right-angles are equal to each other, being all equal to90®j 
 and the line AB is said to be perpendicular to CD. 
 
 Beginners are very apt to confound the terms perpendicular , and 
 plumb or vertical line. A line is vertical when it is at right-angles 
 to the plane of the horizon, or level surface of the earth, or to the 
 surface of water, which is always level. The sides of a house are 
 vertical. But a line may be perpendicular to another, whether it 
 stands upright or inclines to the ground, or even if it lies flat upon 
 it, provided only that it makes the two angles formed by meeting 
 with the other line equal to each other 5 as for instance, if the angles 
 ABC and ABD be equal, the lineAB is perpendicular to CD, w'hat- 
 ever may be its position in other respects. 
 
 9 . When one line, BE {Fig. 3,) stands upon another, CD, so as 
 to incline, the angle EBC, which is greater than a right-angle, is 
 called an obtuse angle ; and that which is less than a right-angle, is 
 called an acute angle, as the angle EBD. 
 
 10. Two angles which have one leg in common, as the angles 
 ABC, and ABE, are called contiguous angles, or adjoining angles j 
 those which are produced by the crossing of two lines, as the angles 
 EBD and CBF, formed by CD and EF, crossing each other, are 
 called opposite or vertical angles. 
 
 1 1. A figure is a bounded space, and is either a surface or a solid. 
 
 12. A superficies, or surface, has length and breadth only. The 
 extremities of a superficies are lines. 
 
 13. A plane, or plane surface, is that which is everywhere per- 
 fectly flat and even, or which will touch every part of a straight line, 
 in whatever direction it may be laid upon it. The top of a marble 
 slab, for instance, is an example of this, which a strait edge will 
 touch in every point, so that you cannot see light any where betv/een. 
 
 14. A curved surface is that which will not coincide with a straight 
 line in any part. Curved surfaces may be either convex or concave. 
 
 15. A convex surface is when the surface rises up in the middle, 
 as, for instance, a part of the outside of a globe. 
 
 16. A concave surface is when it sinks in the middle, or is hollow, 
 and is the contrary to convex. 
 
 A surface may be bounded either by straight lines, curved lines, or 
 both these. 
 
 17. Every surface, bounded by straight lines only, is called a 
 polygon. If the sides are all equal, it is called a regular polygon. If 
 they are unequal, it is called an irregular pjolygon. Every polj’gon, 
 whether equal or unequal, has the same number of sides as angles, 
 and tliey are denominated sometimes according to the number of 
 sides, and sometimes from the number of angles they contain. Thus a 
 figure of three sides is called a triangle, and a figure of four sides a 
 ([uadr angle. 
 
 A pentagon is a polygon of five sides.^ 
 
G E O M E T R Y 
 
 I'l. 89. 
 
 w 
 
 y^eietJtP^i^ t: ^ ^ 
 
.APPENDIX. 
 
 675 
 
 A hexagon has six sides. 
 
 A heptagon seven sides. 
 
 An octagon eight sides. 
 
 A nonagon nine sides. 
 
 A decagon ten sides. 
 
 An undecagon eleven sides. 
 
 A duodecagon twelve sides. 
 
 When they have a greater number of sides, it is usual to call them 
 polygons of 13 sides, of 14 sides, and so on. 
 
 Triangles are of different kinds, according to the lengths of their sides. 
 
 18. An equilateral triangle has all its sides equal, as ABC, Fig. 4. 
 
 19. An isosceles triangle has two equal sides, as DBF, Fig. 5. 
 
 20. A scalene triangle has all its sides unequal, as GHI, Fig. 
 
 Triangles are also denominated according to the angles they contain. 
 
 21. A right-angled triangle is one that has in it a right angle, as 
 ABC, Fig. 7. 
 
 22. A triangle cannot have more than one right-angle. The side 
 opposite to the right-angle B, as AC, is called the hypothenuse, and 
 is always the longest side. 
 
 23. An ohtuse-angled triangle has one obtuse-angle, as Fig. 8. 
 
 24. An acute-angled triangle has all its angles acute, as Fig. 4. 
 
 25. An isosceles, or a scalene triangle, may be either right- 
 angled, obtuse, or acute. 
 
 26. Any side of a triangle is said to subtend the angle opposite to 
 it : thus AB (Fig. 7)t subtends the angle ACB. 
 
 27. If the side of a triangle be drawn out beyond the figure, as 
 AD (Fig. 8), the angle A, or CAB, is called an internal angle, and 
 the angle CAD, or that without the figure, an external angle. 
 
 28. A quadrangle is also called a quadrilateral figure. They are 
 of various denominations, as their sides are equal or unequal, or as all 
 their angles are right-angles or not. 
 
 29. Every four-sided figure whose opposite sides are parallel, is 
 called a parallelogram. Pi'ovided that the sides opposite to each 
 other be parallel, it is immaterial whether the angles are right or 
 not. Fig. 9, 10, 11, and 12, are all parallelograms. 
 
 30. When the angles of a parallelogram are all right-angles, it is 
 called a rectangular parallelogram or a rectangle t as Fig. 1 1 and 12. 
 
 3 1 . A rectangle may have all its sides equal, or only the opposite 
 sides equal. When all its sides are equal, it is called a square, as 
 Fig. 12. 
 
 32. When the opposite sides are parallel, and all the sides equal 
 to each other, but the angles not right-angles, the parallelogram is 
 called a rhombus, as Fig. 10. 
 
 33. A parallelogram having all its angles oblique, an<i only its 
 
 opposite equal, is called a rhomboid, as Fig. 9. , 
 
 34. When a quadrilateral or four-sided figure has none of its sides 
 parallel, it is called a trapezium, as Fig. 13 j consequently every 
 quadrangle, or quadrilateral which is not a parallelogram, is a tra- 
 pezium. 
 
 2x2 
 
APPENDIX. 
 
 676 
 
 35. A trapexo'id has only one pair of its sides parallel, as Fig. 14. 
 
 36. A diagonal is a right line drawn between any two angles that 
 are opposite in a polygon, as \K,Fig. 15. In parallelograms the 
 diagonal is sometimes called the diameter, because it passes through 
 the centre of tlie figure. 
 
 37. Complements of a parallelogram. If any point, as E (Fig, 
 
 1 5y, be taken in the diagonal of a parallelogram, and through that 
 point two lines are drawn parallel to the sides, as AB, CD, it will 
 be divided into four parallelograms, DD, L, F, GG, The two divi- 
 sions, L, F, through which the diameter docs not pass, are called 
 the complements. 
 
 38. Base of a figure is the side on which it is supposed to stand 
 erect, as AB, and CD, Fig. 16. 
 
 39. Altitude of a figure is its perpendicular height from the base 
 to the highest part, as EF, Fig. 16. 
 
 40. Area of a plane figure, or other surface, means the quantity of 
 space contained within its boundaries, expressed in square feet, 
 yards, or any other superficial measure, 
 
 41. Similar figures are such as have the same angles, and whose 
 sides are in the same proportion, as Fig. 17. 
 
 42. Equal figures are such as have the same area or contents. 
 
 43. A circle is a plane figure, bounded by a curve line returning 
 into itself, called its circumference, ABCD (Fig. \SJ, every where 
 equally distant from a point E within the circle, which is called the 
 centre. 
 
 44. The radius of a circle is a straight line drawn from the centre 
 to the circumference, as EF (Fig. 18J. The radius is the opening 
 of the compass when a circle is described j and consequently all the 
 radii of a circle must be equal to each other. 
 
 45. A diameter of a circle is a straight line drawn from one side 
 of the circumference to the other through the centre, as CB (Fig. 18^. 
 Every diameter divides the circle into two equal parts. 
 
 46. A segment of a circle is a part of a circle cut off by a straight 
 line drawn across it. This straight line is called the chord. A seg- 
 ment may be either equal to, greater, or less than a semi-circle, 
 which is a segment formed by the diameter of the circle, as CEB, 
 and is equal to half the circle. 
 
 47. A tangent is a straight line, drawn so as just to touch a circle 
 without cutting it, as GH {Fig. 18). The point A, where it touches 
 the circle, is called the point contact. And a tangent cannot touch 
 a circle in more points than one. 
 
 48. A sector of a circle is a space comprehended between two radii 
 and an arc, as BIK {Fig. 19). 
 
 49. The circumference of every circle, whether great or small, is 
 supposed to be divided into 360 equal parts, called degrees ; and 
 every degree into 60 parts, called minutes j and every minute into 
 60 seconds. To measure the inclination of lines to each other, or 
 angles, a circle is described round the angular point, as a centre, as 
 IK, Fig. 19 ; and according to the number of degrees, minutes, and 
 
APPENDIX., 
 
 677 
 
 seconds, cut oflf by the sides of the angle, so many degrees, minutes, 
 and seconds, it is said to contain. Degrees are marked by minutes 
 by ^ and seconds by " ; thus an angle of 48 degrees, 15 minutes, and 
 7 seconds, is written in this manner, 48° 15' 7". 
 
 50. A solid is any body that has length, breadth, and thickness : 
 a book, for instance, is solid, so is a sheet of paper ; for though its 
 thickness is very small, yet it has some thickness. The boundaries 
 of a solid are surfaces. 
 
 51. Similar solids are such as are bounded by an equal number of 
 similar planes. 
 
 52. A prism is a solid, of which the sides are parallelograms, and 
 the two ends or bases are similar polygons, parallel to each other. 
 Prisms are denominated according to the number of angles in the 
 base, triangular prisms, quadrangular, heptangular, and so on, as 
 Fig. 20, 21, 22,23. If the sides are perpendicular to the plane of 
 the base, it is called an upright prism j if they are inclined, it is 
 called an ohlique prism. 
 
 53. When the base of a prism is a parallelogram, it is called a 
 parallelopipedon, as Fig. 22 and 23. Hence, a parallelopipedon is a 
 solid, terminated by six parallelograms. 
 
 54. When all the sides of a parallelopipedon are squares, the solid 
 is called a cube, as Fig. 23. 
 
 55. A rhomboid is an oblique prism, whose bases are parallelo- 
 grams. {Fig. 24.) 
 
 56. A pyramid AB {Fig. 25 and 26) is a solid, bounded by, or 
 contained within, a number of planes, whose base may be any poly- 
 gon, and whose faces are triangles terminated in one point, B, com- 
 monly called the summit, or vertex of the pyramid. 
 
 57. When the figure of the base is a triangle, it is called a trian- 
 gular pyramid ; when the figure of the base is a quadrilateral, it is 
 called a quadrilateral pyramid, &c. 
 
 58. A pyramid is either regular or irregular, according as the base 
 is regular or irregular. 
 
 59* A pyramid is also right or upright, or it is oblique. It is 
 right, when a line drawn from the vertex to the centre of the base, 
 is perpendicular to it, as Fig. 25 ; and oblique, when this line inclines, 
 as Fig. 26. 
 
 60. A cylinder is a solid {Fig, 27 and 28) generated or formed by 
 the rotation of a rectangle about one of its sides, supposed to be at 
 rest j this quiescent side is called the axis of the cylinder. Or it may 
 be conceived to be generated by the motion of a circle, in a direction 
 perpendicular to its surface, and always parallel to itself. 
 
 61. A cylinder is either right or oblique, as the axis is perpendicu- 
 lar to the base or inclined. 
 
 62. Every section of a right cylinder taken at right-angles to its 
 axis, is a circle ; and every section taken across the cylinder, but 
 oblique to the axis, is an ellipsis. 
 
 63. A circle being a polygon of an infinite number of sides, it fol- 
 
APPENDIX. 
 
 G78 
 
 lows, that the cylinder may be conceived as a prism, having such 
 polygons for bases. 
 
 64. A cone is a solid {Fig. 29 and 30) having a circle for its base, 
 and its sides a convex surface, terminating in a point A, called the 
 vertex or apex of the cone. It may be conceived to be generated by 
 the revolution of a right-angled triangle about its perpendicular. 
 
 65. A line drawn from the vertex to the centre of the base is the 
 axis of the cone. 
 
 66. When this line is perpendicular to the base, the cone is called 
 an upright or right cone ; but when it is inclined, it is called an 
 oblique cone. 
 
 67. If it be cut through the axis, from the vertex to the base, the 
 section will be a triangle. 
 
 68. If a right cone be cut by a plane at right-angles to the axis, 
 the section will be a circle. 
 
 69. If it be cut oblique to the axis, and quite across from one side 
 to the other, the section will be an ellipsis, as Fig. 31. A section of 
 a cylinder, made in the same manner, is also an ellipsis ; and this is 
 easily conceived j but it does not appear so readily to most people, 
 that the oblique section of a cone is an ellipsis : they frequently ima- 
 gine that it will be wider at one end than the other, or what is called 
 an oval, which is of the shape of an egg. But that this is a mistake, 
 any one may convince himself, by making a cone, and cutting it across 
 obliquely : it will be then seen, that the section, in whatever direc- 
 tion it is taken, is a regular ellipsis j and this is the case, whether 
 the cone be right or oblique, except only in one case, in the oblique 
 cone, which is, when the section is taken in a particular direction, 
 which is called sub-contrary to its base. 
 
 70. When the section is made parallel to one of the sides of the 
 cone, as Fig. 32, the curve ABC, which bounds the section, is called 
 a parabola. 
 
 71. When the section is taken parallel to the axis, as Fig, 33, the 
 curve is called an hyperbola. 
 
 These curves, which are formed by cutting a cone in different direc- 
 tions, have various properties, which are of great importance in as- 
 tronomy, gunnery, perspective, and many other sciences. 
 
 72. A sphere is a solid, terminated by a convex surface, every 
 point of which is at an equal distance from a point within, called the 
 centre. Fig. 34. 
 
 73. It may be conceived to be formed by making a semicircle re- 
 volve round its diameter. This may be illustrated by the process of 
 forming a ball of clay by the potter’s wheel, a semicircular mould 
 being used for the purpose. The diameter of the semicircle, round 
 which it revolves, is called the axis of the sphere. 
 
 74. The ends of the axis are called poles. 
 
 75. Any line passing through the centre of the sphere, and termi- 
 nated by the circumference, is a diameter of the'sphere. 
 
 76. Every section of a sphere is a circle ; every section taken 
 
APPENDIX. 6/9 
 
 through the centre ef the sphere, is called a great circlet as AB, Fig. 
 34 ; every other is a lesser circle, as CD. 
 
 77. Any portion of a sphere cut off by a plane, is called a segment ; 
 and when the plane passes through the centre, it divides the sphere 
 into two equal parts, each of which is called a hemisphere. 
 
 78. A conoid is a solid, produced by the circumvolution of a section 
 of the cone, about its axis, and, consequently, may be either an 
 elliptical conoid, a hyperbolical conoid, or a parabolical conoid. When 
 it is elliptical, it is generally called a spheroid. These solids are also 
 called ellipsoid, hyperboloid,, and paraboloid, 
 
 79. A spheroid is a solid {Fig. 35), generated by the rotation of a 
 semi-ellipsis about the transverse or conjugate axis 3 and the centre 
 of the ellipsis is the centre of the spheroid' 
 
 80. The line about which the ellipsis revolves, is called the azis. 
 If the spheroid be generated about the conjugate axis of the semi- 
 ellipsis, it is called a prolate spheroid. 
 
 81. If the spheroid be generated by the semi-ellipsis, by revolving 
 about the transverse axis, it is called an oblong spheroid. 
 
 82- Every section of a spheroid is an ellipsis, except when it is 
 perpendicular to that axis about which it is generated 3 in which case, 
 it is a circle. 
 
 83. All sections of a spheroid parallel to .each other, are similar 
 figures. 
 
 A frustum of a solid, means a piece cut off from the solid, by a 
 plane passed through it, usually parallel to the base of the solid, as 
 the frustum of a cone, a pyramid, &c. 
 
 There is a lower and an upper ft-ustum, according as the piece 
 spoken of does or does not contain the base of the solid. 
 
 84. A regular body is a solid, contained under a certain number of 
 equal and regular plane figures of the same sort. 
 
 85. The faces of the solid are the plane figures under which it is 
 contained 5 and the linear sides, or edges of the solid, are the sides of 
 the plane faces. 
 
 86. The are only five regular bodies : — viz. 1st. the tetraedon, 
 which is a regular pyramid, having four triangular faces ; 2d. the 
 hexaedron, or cube, which has six equal square faces 3 3d. the octae- 
 dron, which has eight triangular faces 5 4th. the dodecaedron, which 
 has twelve pentagonal faces 3 5th. the icosaedron, which has twenty 
 triangular faces. 
 
 Note.— If the figures marked A, B, C, D, E, be exactly drawm on 
 pasteboard, and the lines cut half through, so that the parts be turned 
 up, and glued together, they will represent the five regular bodies, 
 viz. — Fig. A, the tetraedon 3 B, the hexaedron 3 C, the octaedron 3 
 D, the dodecaedron ; and E, the icosaedron. 
 
 . 87. Ratio is the proportion which one magnitude bears to another 
 
 of the same kind, with respect to quantity, aud is usually maked 
 thus, A : B. 
 
 Of these, the first is called the antecedent, and the second the /row- 
 fey wew/. 
 
APPENDIX. 
 
 680 
 
 88 . 1l\\q measure or quantity of a ratio, is conceived by considering 
 what part of the consequent is the antecedent 5 consequently, it is 
 obtained by dividing the consequent by the antecedent. 
 
 89. Three magnitudes or quantities. A, B, C, are said to be pro- 
 portional, when the ratio of the first to the second is the same as 
 that of the second to the third. Thus, 2 , 4, 8 , are proportional, be- 
 cause 4 is contained in 8 as many times as 2 is in 4. 
 
 90. Four quantities. A, B, 0, D, are said to be proportional, when 
 the ratio of the first. A, to the second, B, is the same as the ratio of 
 the third, C, to the fourth, D. It is usually written, A : B :: C : D, 
 or, if expressed in numbers, 2 : 4 :: 8 : 16. 
 
 91. Of Mree proportional quantities, the middle one is said to be a 
 mean proportional between the other two ; and the last a third prO“ 
 portional to the first and second. 
 
 92. Of four proportional quantities, the last is said to be a fourth 
 proportional to the other three, taken in order. 
 
 93. Ratio of equality is that which equal numbers bear to each 
 other. 
 
 94. Inverse ratio is when the antecedent is made the consequent, 
 and the consequent the antecedent. Thus, if 1 : 2 : : 3 : 6 j then, 
 inversely ^2 : 1 :: 6 : 3. 
 
 95. Alternate proportion is when the antecedent is compared with 
 antecedent, and consequent with consequent. Thus, if 2 : 1 :: 6 : 3 ; 
 then, hy alternation, 2 : 6 :: 1 : 3. 
 
 96. Proportion by composition is when the antecedent and conse- 
 quent, taken as one quantity, are compared either with the conse- 
 quent or with the antecedent. Thus, if 2 : 1 :: 6 : 3 5 then, by 
 composition, 2+1:1:: 6+3 : 3, and 2+1 : 2 :: 6 + 3 : 6 . 
 
 97 . Divided proportion is when the difference of the antecedent and 
 consequent is compared either with the consequent or with the ante- 
 cedent. Thus, if 3 : 1 :: 12 : 4 ; then, by division, 3 — 1 : 1 :: 12 — 
 4 : 4, and 3—1 : 3:: 12—4 : 12. 
 
 98. Continued proportion is when the first is to the second as the 
 second to the third 5 as the third to the fourth ; as the fourth to the 
 fifth j and so on. 
 
 99. Compound ratio is formed by the multiplication of several an- 
 tecedents and the several consequents of ratios together, in the fol- 
 lowing manner : 
 
 If A be to B as 3 to 5, B to C as 5 to 8, and C to D as 8 to 6 j 
 
 then A will be D, as 5 l^at is, A : D :: 1:2. 
 
 5x8x6 240 
 
 100. Bisect, means to divide any thing into two equal parts. 
 
 101. Trisect, is to divide any thing into three equal parts. 
 
 102. Inscribe, to draw one figure within another, so that all the 
 angles of the inner figure touch either the angles, sides, or planes of 
 the external figure. 
 
 103. Circumscribe, to draw a figure round another, so that either 
 the angles, sides, or planes of the circumscribed figure, touch all the 
 angles of the figure within it. 
 
APPENDIX. 
 
 681 
 
 104. Rectangle under any hvo lines, means a rectangle which has 
 two of its sides equal to one of the lines, and two of them equal to the 
 other. Also, the rectangle under AB, CD, means AB x CD. 
 
 105. Scales of equal parts. A scale of equal parts is only a straight 
 line* divided into any number of equal parts, at pleasure. Each part 
 may represent any measure you please, as an inch, a foot, a yard, 
 &c. One of these is generally subdivided into parts of the next deno- 
 mination, or into tenths or hundredths. Scales may be constructed in 
 a variety of ways. The most usual manner is, to make an inch, or 
 some aliquot part of an inch, to represent a foot 3 and then they are 
 called inch scales, three-quarter inch scales, half-inch scales, quarter- 
 inch scales, &c. They are usually drawn upon ivory or box-wood. 
 
 106. An axiom is a manifest truth, not requiring any demonstration. 
 
 107. Postulates are things required to be granted true, before we 
 proceed to demonstrate a proposition. 
 
 108. K proposition is when something is either proposed to be done, 
 or to be demonstrated, and is either eJ problem or a theorem. 
 
 109. A problem is^when something is proposed to be done, as some 
 figure to be drawn. 
 
 110. A theorem h when something is proposed to be demonstated 
 or proved. 
 
 111. A lemma is when a premise is demonstrated, in order to ren- 
 der the thing in hand the more easy. 
 
 112. A corollary is an inference drawn from the demonstration of 
 some proposition. 
 
 113. A scholium is when some remark or observation is made upon 
 something mentioned before. 
 
 114. The sign = denotes that the quantities betwixt which it 
 stands, are equal. 
 
 115. The sign -f- denotes that the quantity after it, is to be added 
 to that immediately before it. 
 
 116. The sign — denotes, that the quantity after it is to be taken 
 away or subtracted from the quantity preceding it. 
 
 Geometrical Problems. 
 
 Prob. 1. To divide a given line AB into two equal parts. 
 
 From the points A and B, as centres, and with any opening of the 
 compasses greater than half AB, describe arches, cutting each other 
 in c and d. Draw the line c d 3 and the point E, where it cuts A B, 
 will be the middle required. 
 
 Prob. 2. To raise a perpendicular to a given line A B, from a 
 point given at C, 
 
 Case 1. When tne given point is near the middle of the line, on 
 each side of the point C. Take any two equal distances, C d and 
 C e 3 from d and e, with any radius or opening of the compasses 
 greater than C d or C e, describe two arcs cutting each other in f. 
 Lastly, through the points f, C, draw the line f C, and it will be 
 the perpendicular required; 
 
APrEJ^PIX. 
 
 682 
 
 Case 2, When the point is at, or near the end of the line. Take 
 any point d, above the line, and with the radius or distance d C, de- 
 scribe the arc e C f, catting AB in e and C. Through the centre d, and 
 the point e, draw the line e d f, cutting the arc e C f in f. Through the 
 points f C, draw the line fC, and it will be the perpendicular required. 
 
 Prob.3, From a given point f, to let fall a perpendicular upon a 
 given line AB. 
 
 From the point f, with any radius, describe the arc d e, cutting AB 
 in e and d. From the points e d, with the same or any other radius, 
 describe two arcs, cutting each other in g. Through the points f 
 and g, draw the line f g, and f C will be the perpendicular required. 
 
 Prob. 4. To make an angle equal to another angle which is given, 
 as a B b. 
 
 From the point B, with any radius, describe the arc ab, cutting 
 the legs B a, B b, in the points a and b. Draw the line D e, and 
 from the point D, with the same radius as before, describe the arc e f, 
 cutting D e in e. Take the distance B a, and apply it to the arc e f, 
 from e to f. Lastly, through the points D, f, draw the line D f, and 
 the angle e D f will be equal to tke angle b B a, as was required. 
 
 Prob. 5. To divide a given angle, ABC, into two equal angles. 
 
 From the point B, with any radius, describe the arc AC. From A 
 and C, with the same, or any other radius, describe arcs cutting each 
 in d. Draw the line B d, and it will bisect the angle ABC, as was 
 required. 
 
 Prob. 6. To lay down an angle of any number of degrees. 
 
 There are various methods of doing this. One is by the use of an 
 instrument called a protractor, with a semicircle of brass,having its cir- 
 cumference divided iuto degrees. Let AB be a given line, and let it 
 be required to draw from the angular point A, a line making, with 
 AB, any number of degrees, suppose 20. Lay the straight side of 
 the protractor along the line AB, and count 20° from the end B of 
 the semicircle i at C, which is 20° from B, mark ; then, removing 
 the protractor, draw the line AC, which makes, with AB, the 
 angle required. Or, it may be done by a divided line, usually drawn 
 upon scales, called a line of chords. Take 60° from the line of 
 chords, in the compasses, and setting one at the angular point B, 
 Prob. 4, with that opening as a radius, describe an arch, as a b : then 
 take the number of degrees of which you intend the angle to be, and 
 set it from b to a, then is a B b the angle required. 
 
 Prob. 7. Through a given point C, to draw a line parallel to a 
 gtven line AB. 
 
 Case 1. Take any point d, in AB ; upon d and C, with the distance 
 C d, describe two arcs, e C, and d f, cutting the line AB in e and d. 
 Make d f equal to e C 5 through C and f draw C f, and it will be 
 the line required. 
 
 Case 2. When the parallel is to be at a given distance from AB. 
 From any two points, c and d, in the line AB, with a radius equal to 
 tl e given distance, describe the arcs e and f : draw the line CB to 
 
->1 fca to 
 
 GEOMETRY 
 
 P1.90. 
 
 
 yeeUi S(o<ideif ^ JS* 
 
APPENDIX. 683 
 
 touch those arcs without cutting them^ and it will be parallel to AI3, 
 as was required. 
 
 Prol, 8. To divide a given line AB, into any proposed number of 
 equal parts. 
 
 From A, one end of the line, draw A c, making any angle with 
 AB and from B, the other end, draw B d, making the angle A B d 
 equal to B A c. In each of these lines, Ac, B d, beginning at A and 
 B, set off as many equal parts, of any length, as AB is to be divided 
 into. Join the points C 5, 46, 57, and AB will be divided as re- 
 quired. 
 
 Proh, 9. To find the centre of a given circle, or of any one already 
 described. Draw any chord AB, and bisect it with the perpendicu- 
 lar CD, Bisect CD with the diameter EF, and the intersection O 
 will be the centre required. 
 
 Prob* 10. To draw a tangent to a given circle that shall pass 
 through a given point, A. 
 
 From the centre O, draw the radius OA. Through the point A, 
 draw DE perpendicular to OA, and it will be the tangent required.? 
 
 Prob. 1 1. To draw a tangent to a circle, or any segment of a circle 
 ABC, through a given point B, without making use of the centre of 
 the circle. 
 
 Take any two equardi visions upon the circle, from the given point 
 B, towards d and e, and draw the chord e B. Upon B, as a centre, 
 with the distance B d, describe the arc f d g, cutting the chord e B 
 in f. Make d g equal to d f j through g draw g B, and it will be the 
 tangent required. 
 
 Prob. 12. Given three points. A, B, C, not in a straight line, to 
 describe a circle that shall pass through them. 
 
 Bisect the lines AB, BC, by the perpendiculars a b, b d, meeting 
 at d. Upon d, with the distance d A, d B, or d C, describe ABC, 
 and it will be the required circle. 
 
 Prol. 13. To describe the segment of a circle to any length AB, 
 and height CD. 
 
 Bisect AB by the perpendicular D g, cutting AB in c. From c 
 make cD, on the perpendicular, equal to CD. Draw AD, and bisect 
 it by a perpendicular e f, cutting D g in g. Upon g the centre, de- 
 scribe ADB, and it will be the required segment. 
 
 Prob. 14. To describe the segment of a circle by means of two 
 rules, to any length AB, and perpendicular height CD in the middle 
 of AB, without making use of the centre. 
 
 Place the lales to the height at C ; bring the edges close to A and 
 B fix them together at C, and put another piece across them to 
 keep them fast. Put in juns at A and B, then move the rulers round 
 these pins, holding a pencil at the angular point C, which will de- 
 scribe the segment. 
 
 Proh. 15. In any given triangle to inscribe a circle. 
 
 Bisect any two angles A and C, with the lines AD and DB. From 
 D, the point of intersection, let fall the perpendicular DE ; it will be 
 the radius of the circle required. 
 
684 
 
 APPENDIX. 
 
 . Proh, 16. In a given square, to describe a regular octagon. 
 
 Draw the diagonals AC and BD, intersecting at e. Upon the 
 points A, B, C, D, as centres, with a radius e C, describe the arcs 
 h e 1, k e n, meg, f e i. Join f n, m h, k i, 1 g, and it will be the 
 required octagon, 
 
 Prob. 17. In a given circle, to describe any regular polygon. 
 
 Divide the circumference into as many parts as there are sides in 
 the polygon to be drawn, and join the points of division. 
 
 Proh. 18. Upon a given line AB, to construct an equilateral tri- 
 angle. 
 
 Upon the points A and B, with a radius equal to AB, describe 
 arches cutting each other at C. Draw AC and BC, and ABC will 
 be the triangle required. 
 
 Prob, 19. To make a triangle, whose sides shall be equal to three 
 given lines D, E, F, any two of them being greater than the third. 
 
 Draw AB equal to the line D. Upon A, with the radius F, de- 
 scribe an arc CD. Upon B, with the radius E, describe another arc 
 intersecting the former at C. Draw AC and CB, and ABC will be 
 the triangle required. 
 
 Proh. 20, To make a trapezium equal and similar to a given tra- 
 pezium ABCD. 
 
 Divide the given trapezium ABCD into two triangles, by the dia- 
 gonal DB. Make EF equal to AB ; upon EF construct the triangle 
 EFH, whose sides shall be respectively equal to those of the triangle 
 ABD, by the last problem. Upon HF, which is equal to DB, con- 
 struct the triangle HFG, whose sides are respectively equal to DBC ; 
 then EFGH will be the trapezium required. 
 
 By the help of this problem, any plan may be copied ; as every 
 figure, however irregular, may be divided into triangles. Upon this 
 the practice of land-surveying and making plans of estates, is founded. 
 
 Proh. 21. To make a square equal to two given squares. Make 
 the sides DE and DF of the two given squares A and B, form the 
 sides of a right-angled triangle FDE ; draw the hypothenuse FE ; 
 on it describe the square EFGH ; and it will be the square required. 
 
 Proh. 22. Two right lines AB, CD, being given, to find a third 
 proportional. Make an angle HE! at pleasure j from E make EF 
 equal to AB, and EG equal to CD : join FG. Make El equal to 
 EF, and draw HI parallel to FG j then EH will be the third pro- 
 portional required ; that is, EF : EG : : EH : El, or AB ; CD : : 
 CD:EU 
 
 Proh. 23. Three lines being given, to find a fourth proportional. 
 Make the angle HGI at pleasure 5 from G make GH equal to AB, 
 GI equal to CD, and join HI. Make GK equal to EFj draw KC 
 through K, parallel to HI j then GL will be the fourth proportional 
 required, that is, GH : GI : : GK : GL, or AB : CD : : EF : GL. 
 
 Prob. 24. To divide a given line AB in the same proportion as 
 another CD is divided. 
 
 Make any angle KHI, and make ffl equal to AB ; then apply tlie 
 
APPENDIX. 
 
 685 
 
 several divisions of CD, from H to K, and join KI. Draw the lines 
 h e, i f, k g, parallel to IK j and the line HI will be divided in e, f, 
 g, as was required. 
 
 Proh. 25, Between two given lines AB and CD to find a mean 
 proportional. 
 
 Draw the right line EG, in which make EF equal to AB, and FG 
 equal to CD. Bisect EG in H, and with HE or HG, as radius, de- 
 scribe the semicircle EIG. From F draw FI perpendicular to EG, 
 cutting the circle in I j and IF will be the mean proportional re- 
 quired. 
 
 Proh. 26. To describe an ellipsis. 
 
 If two pins are fixed at the points E and F, a string being put 
 about them, and the ends tied together at C j the point C being 
 moved round, keeping the string stretched will describe an ellipsis. 
 
 The points E and F, where the pins were fixed, are called the foci. 
 
 The line AB passing through the foci, is called the transverse axis. 
 
 The point G bisecting the transverse axis, is the centre of the 
 ellipsis. 
 
 The line CD crossing this centre at right-angles to the transverse 
 axis, is the conjugate axis. 
 
 The latus rectum is a right line passing through the focus at F, at 
 right-angles to the transverse axis terminated by the curve : this is 
 also called the parameter. 
 
 A diameter is any line passing through the centre, and terminated 
 by the curve. 
 
 A conjugate diameter to another diameter, is a line drawn through 
 the centre, parallel to a tangent at the extreme of the other diame- 
 ter, and terminated by the curve. 
 
 A double ordinate is a line drawn through any diameter parallel to 
 a tangent, at the extreme of that diameter terminated by the curve. 
 
 Proh. 26. The transverse axis AB, and conjugate axis CD, of any 
 ellipsis, being given, to find the two foci, and from thence to describe 
 the ellipsis. 
 
 Take the semi-transverse AE, or EB, and from C as a centre, de- 
 scribe an arc, cutting AB at F and G, which are the foci. Fix pins 
 in these points ; a string being stretched about the joints FCG, the 
 ellipsis is described as above. 
 
 Proh. 27. The same being given, to describe an ellipsis by a trammel. 
 
 The trammel is an instrument consisting of two rulers fixed at 
 right-angles to each other, with a groove in each. A rod with two 
 moveable nuts works in this groove, and, by means of a pencil fixed 
 in the end of the rod, describes the curve. The operation is as follows: 
 
 Let the distance of the first pin at B, from the pencil at A, be 
 equal to half the shortest axis, and the distance of the second pin at 
 C, from A, to half the longest axis j the pins being put in the 
 grooves, move the pencil at A, which will describe the ellipsis. 
 
 Proh. 28. To draw the representation of an ellipsis with a compass 
 to any length AB, and width CD. 
 
 Draw BP parallel and equal to EC, and bisect it at 1 j then draw 
 
APPENDIX. 
 
 686 
 
 1 C and PD, cutting each other at K j bisect KC by a perpendicular 
 meeting CD in O ; and on O, with the radius OC, describe the 
 quadrant CGQ. 
 
 Through Q and A, draw QG, cutting the quadrant at G ; then 
 draw GO, cutting AB at M j make EL equal to EM, also EN equal 
 to EO. From N, through M and L draw NH and NI j then M, L, 
 N, O, are the four centres by which the four quarters of the ellipsis 
 are drawn. ' 
 
 It must be observed, that this is not a true ellipsis, but only an 
 approximation to it 5 for it is impossible to draw a perfect ellipsis 
 by means of compasses, which can only describe parts of circles. 
 But the curve of an ellipsis differs essentially from that of a circle in 
 every part ; and no portions of circles put together, can ever form an 
 ellipsis. But by this means, a figure may be drawn, which ap- 
 proaches nearly to an ellipsis, and therefore may be often substi- 
 tuted for it when a trammel cannot be had, or when the ellipsis is 
 too small to be drawn by it. At the joining of the portions of circles 
 in this operation, the defect is not perceivable 5 and the best way is 
 not to join them quite, and to help the curve by hand. 
 
 Prob. 29. An ellipsis, ACDB, being given, to find the transverse 
 and conjugate axis. 
 
 Draw any two parallel lines, AB and CD, cutting the ellipsis at 
 the points A, B, C, D ; bisect them in e and f. Through e and f, 
 draw GH, cutting the ellipsis at G and H j bisect GH at 1 5 and it 
 will give the centre. 
 
 Upon I, with any radius, describe a circle, cutting the ellipsis in 
 the four points k, 1, m, n 5 join k, 1, and m, n; bisect k 1, or m n, at 
 
 0 or p. Through the points o, 1, or 1, p, draw QR, cutting the 
 ellipsis at Q and R j then QR will be the transverse axis. Through 
 
 1 draw TS, parallel to k 1, cutting the ellipsis at T and S j and TS 
 will be the conjugate axis, 
 
 Prob. 30. To describe an ellipsis similar to a given one ADBC, 
 to any given length IK, or to a given width ML. 
 
 Let AB and CD be the two axes of the given ellipsis. Through 
 the points of contact A,D,B,C, complete the rectangle GEHF ; draw 
 the diagonals EF and GH : they will pass through the centre at R. 
 Through I and K draw PN and OQ parallel to CD, cutting the diago- 
 nals EF and GH, atP,N,Q,0. Join PO and NQ, cutting CD at L 
 and M j then IK is the transverse, and ML the conjugate axis of an 
 ellipsis, that will be similar to the given ellipsis ADBC, which may 
 be described by some of the foregoing methods. 
 
 Prob. 31. To describe a parabola. If a thread equal in length to 
 BC, be fixt at C, the end of a square ABC, and the other end be 
 fixt at F j and if the side AB of the square be moved along the line 
 AD, and if the point E bo always kept close to the edge BC of the 
 square, keeping the string tight, the pointer pin E will . describe a 
 curve EGIH, called a parabola. 
 
 The focus of the parabola is the fixed point F, about which the 
 string revolves. 
 
GEO ME TRY 
 
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APPENDIX 
 
 687 
 
 The directrix is the line AD, which the side of the square moves 
 along. 
 
 The axis is the line LK, drawn through the focus F, perpendicular 
 to the directrix. 
 
 The vertex is the point I, where the line LK cuts the curve. 
 
 The latus rectum, or parameter, is the line GH passing through 
 the focus F, at right-angles to the axis IK, and terminated by the 
 curve. 
 
 The diameter is any line MN, drawn parallel to the axis IK. 
 
 A doulle ordinate is a right line RS, drawn parallel to a tangent at 
 M, the extreme of the diameter MN, terminated by the curve. 
 
 The abscissa is that part of a diameter contained between the 
 curve and its ordinate, as MN. 
 
 Proh. 32. To describe a parabola, by finding points in the curve ; 
 the axis AB, or any diameter being given, and a double ordinate CD. 
 
 Through A draw EF parallel to CD j through C and D draw DF 
 and CE parallel to AB, cutting EF at E and F. Divide BC and BD, 
 each into any number of equal parts, as four j likewise divide CE’ 
 and DF into the same number of equal parts. Through the points 1, 
 2, 3, &c. in CD, draw the lines la, 2 b, 3 c, &c. parallel to CD j 
 also through the points 1,2, 3, in CE and DF, draw the lines 1 A, 
 2 A, 3 A, cutting the parallel lines at the points a, b, c ' then the 
 points a, b, c, are in the curve of the parabola. 
 
 Prol. 33. To describe an hyperbola. 
 
 IfB and C are tw’o fixed points, and a rule AB be made moveable 
 about the point B, a string ADC being tied to the other end of the 
 rule, and to the point C j and if the point A be moved round the 
 centre B, towards G, the angle D of the string ADC, by keeping 
 it always tight and close to the edge of the rule AB, will describe a 
 curve DHG, called an hyperbola. 
 
 *■11 the end of the rule at B were made moveable about the point 
 C,, the string being tied from the end of the rule A to B, and a 
 curve being described after the same manner, is called an opposite 
 hyperbola. 
 
 The foci are the two points B and C, about which the rule and 
 string revolves. 
 
 Ttie transverse axis is the line IH terminated by the two cun*es 
 passing through the foci, if continued. 
 
 The centre is the point M, in the middle of the transverse axis IH. 
 
 The ccmjugate axis is the line NO, passing through the centre M, 
 an&l terminated by a circle from H, whose radius is MC, at N and O. 
 
 A diameter is any line VW, drawn through the centre M, and ter- 
 minated by the opposite curves. 
 
 Conjugate diameter to another, is a line drawm through the centre, 
 parallel to a tangent with either of the curves, at the extreme of the 
 other diameter terminated by the curves. 
 
 Abscissa is when any diameter is continued w ithin the curve, ter- 
 minated by a double ordinate and the curve j then the part within is. 
 called the abscissa. 
 
APPENDIX. 
 
 688 
 
 Double ordinate is a line drawn through any diameter parallel to its 
 conjugate, and terminated by the curve. 
 
 Parameter or latus rectum^ is a line drawn through the focus, per- 
 pendicular to the transverse axis, and terminated by the curve. 
 
 Proh. 34. To describe an hyperbola by finding points in the curve, 
 having the diameter or axis AB, its abscissa BG, and double ordi- 
 nate DC. 
 
 Through G draw EF, parallel to CD j from C and D draw CE and 
 DF, parallel to BG, cutting EF in E and F. Divide CD and BD, 
 each into any number of equal parts, as four ; through the points of 
 division, 1, 2, 3, draw lines to A. Likewise divide EC and DF into 
 the same number of equal parts, viz. four j from the divisions on CE 
 and DF, draw lines to G ; a curve being drawn through the intersec- 
 tions at G, a, b, &c. will be the hyperbola required. 
 
 Remarks. — In a circle, the half chord DC, is a mean proportional 
 between the segments AD, DB of the diameter AB perpendicular to 
 it. That is AD : DC : : DC : DB. 
 
 2. The chord AC is a mean proportional between AD and the di- 
 ameter AB. And the chord BC a mean proportional between DB 
 and AB. 
 
 That is, AD : AC : : AC : AB, 
 and BD : BC : : BC : AB. 
 
 3 The angle ACB, in a semicircle, is always a right. 
 
 4. The square of the hypotenuse of a right-angled triangle, is equal 
 to the squares of both the sides. 
 
 That is, AC^ = AD2 + DC% 
 and BC2 = BD^ + DC®, 
 and AB^= AC^ + BC®. 
 
 5. Triangles that have all the three angles of the one respectively 
 equal to all the three of the other, are called equiangular triangles, 
 or similar triangles. 
 
 6. In similar triangles, the like sides, or sides opposite the equal 
 angles, are proportional. 
 
 7. The areas, or spaces, of similar triangles, are to each other, 
 as the squares of their like sides. 
 
 MENSURATION OF SUPERFICIES. 
 
 Proh. 1. To find the area of a parallelogram: whether it be a 
 square, a rectangle, a rhombus, or a rhomboid. 
 
 Multiply the length by the breadth, or perpendicular height, and 
 the product will be the area. 
 
 Ex. 1. To find the area of a square, whose side is 6 inches, or 6 
 feet, &c. 
 
 6 
 
 6 
 
 36 Ansr 
 
APPENDIX. 689 
 
 2. To find the area of a rectangle, whose length is 9, ana oreadth 
 4 inches, or feet, &c. 
 
 9 
 
 4 
 
 Ansr. 36 
 
 3. To find the area of a rhombus, whose length is 6 chains, and 
 perpendicular height 5. 
 
 5 
 
 Ansr. 30 
 
 Prob, 2. To find the Area of a Triangle. 
 
 Rule 1 . Multiply the base by the perpendicular height, and half 
 the product will be the area. 
 
 Rzde 2. When the three sides only are given : Add the three sides 
 together, and take half the sum 3 from the half sum subtract each 
 side separately 3 multiply the half sum and the three remainders con- 
 tinually together 3 and the square root of the last product will be the 
 area of the triangle. 
 
 Ex. Required the area of the triangle whose base is 6 feet, and 
 perpendicular height 5 feet. 
 
 6 
 
 5 
 
 2) 30 (15 Ansr. 
 
 Proh. 3. To find one Side of a right-angled Triangle, having the 
 other two Sides given. 
 
 The square of the hypotenuse is equal to both the squares of the 
 two legs. Therefore, 
 
 1. To find the hypotenuse 3 add the squares of the two legs to- 
 gether, and extract the square root of the sum. 
 
 2. To find one leg ; subtract the square of the other leg from the 
 square of the hypotenuse, and extract the root of the difference. 
 
 Ex. 1. Required the hypotenuse of a right-angled triangle, whose 
 base A B is 40, and perpendicular BC 30. 
 
 4 3 
 
 4 3 
 
 16 9 
 
 9 
 
 25 (5 the square root of the sum of the two squares, being 
 
 25 the hypotenuse AC. 
 
APPENDIX. 
 
 690 
 
 2. What is the perpendicular of a right-angled triangle, whose 
 base AB is 56, and hypotenuse, AC 65 ? 
 
 56 65 
 
 56 65 
 
 336 . 325 
 280 390 
 
 3136 4225 
 
 3136 
 
 1089 ( 33 The perpendicular, which is the root 
 9 of the remainder of the square of the 
 
 hypotenuse AC, when the square 
 
 63 I 189 of AB has been subtracted. 
 
 3 1 189 
 
 Prol;. 4. To find the Area of a Trapezoid. 
 
 Multiply the sura of the two parallel sides by the perpendicular 
 distance between them, and half the product will be the area. 
 
 Er. In a trapezoid, the parallel sides are AB 7, and CD 12, 
 and the perpendicular distance AP or CN is 9 : required the area. 
 
 7 
 
 12 
 
 19 
 
 9 
 
 171 
 
 85| the area. 
 
 ProL 5. To find the Area of a Trapezium. 
 
 Case for any trapezium . — Divide it into two triangles by- a dia- 
 gonal ; then find the areas of these triangles, and add them together. 
 
 Note. If two perpendiculars be let fall on the diagonal, from tlie 
 other two opposite angles, the sum of these perpendiculars being 
 multiplied by the diagonal, half the product will be the area of the 
 trapezium. 
 
 Ear. 'To find the area of the trapezium ABCD, the diagonal AC 
 being 42 , the perpendicular BF 18 , and the perpendicular DE 16. 
 
 18 
 16 
 
 34 
 
 42 
 
 68 
 
 136 
 
 2 ) 1428 
 
 714 the answer. 
 
MElSrSUR-\TIOK 
 
 I 
 
 & StvcJd^ sc 3 St Scra/id. 
 
APPENDIX. 
 
 Prob. 6. To find the Area of an Irregular Polygon. 
 
 Draw diagonals dividing the figure into trapeziums and triangles. 
 Then find the areas of all these separately, and their sum will be the 
 content of the whole irregular figure. 
 
 Ex. To find the content of the irregular figure ABCDEF, in 
 which are given the following diagonals and perpendiculars : namely, 
 
 c. a = 10 
 
 d. f = 6 
 
 c.i = 4 
 
 k.e = 2 
 
 m. f = 3 
 
 n. b = 4 
 
 For trapez. d c f e. 
 
 ci. 4 
 ke. 2 
 
 6 
 
 df. 6 
 2)36 
 
 18 contents. 
 
 18 contents d. c. f e 
 35 c. f. a b 
 
 ^ — 
 
 53 contents of the irregular 
 — polygon. 
 
 Prob. 7. To find the Area of a Regular Polygon. 
 
 ’ ■ Pu/e. Multiply the perimeter of the figure, or sum of its sides, 
 by the perpendicular falling from its centre upon one of its sides, and 
 half the product will be the area. 
 
 Prob. 8. In a Circular Arc, having any two of the following lines, 
 viz. the chord AB, the versed sine DP, the chord of half the arc 
 AD, and the diameter, or the radius AC or CD given, to find the others. 
 - If any two of these lines be given, two sides of one of the right- 
 angled triangles, APC or A PD, will be known, and from them the 
 remaining side, and other lines in the arc, may be found by Prob. 3. 
 
 Suppose AB and PD be given, then, by Prob. 3., the half of AB, 
 or AP is a mean proportional between DP and PC CD ; for PC -p 
 CD + PD is the diameter of the circle, half of which is the radius 
 or CA, and by Prob. 3, AC® — AP^ = CP^, and AP‘^ + PD^ = AD^ 
 Suppose CD and AB be given, then half of AB = AP, and 
 
 CD = AC j therefore V - AP^ _ cp, and CD - CP = PD. 
 V PD* + AP2 = AD. 
 
 Prob. 9. To find the Diameter and Circumference of a Circle, the 
 one from the other. 
 
 jRule 1 , As 7 is to 22, so is the diameter to the circumference. 
 
 As 22 is to 7, so is the circumference to the diameter. 
 2y2 
 
 For trapez. c f a b 
 n.b. 4 
 m.f. 3 
 
 7 
 
 c.a. 10 
 2)70 
 
 35 <;ontents. 
 
C92 
 
 APPENDIX. 
 
 Rule 2. As J 13 is to 355, so is the diameter to the circumference. 
 
 As 355 is to 113, so is the circumference to the diameter 
 Rule 3. As 1 is to 3' 14 IS, so is the diameter to the circumference. 
 
 As 3‘14r6 is to 1, so is the circumference to the diameter. 
 Ex', 1. lo find the circumference of a circle, whose diameter AB 
 
 3 10 . 
 
 By Rule 1. 
 
 7: 22:: 10: 31*42857 
 
 10 , 
 
 7) 220 
 
 31-f 
 
 or 3142857 ans. 
 
 By Rule 2. 
 
 113:355:: 10:31tVt 
 10 
 
 113 ) 3550 ( 31-41593 
 — • the ans. ■ 
 
 160 
 
 470 
 
 180 
 
 670 
 
 By Rule 3. 
 
 1 : 3-1416 : : 10 : 31*416 
 the circumference nearly, 
 the true circumference 
 being 
 
 31-4159265358979, &c. 
 
 So that the 2d rule is 
 nearest the truth. 
 
 1050 
 
 330 
 
 ^ 2. To find tl»e diameter when the circumference is 100. 
 
 By Rule 1. 
 
 7 X 25 = 175 , , 
 
 22 : 7 : : 50 : — j-j — _ “jj- = 15 tt .= 15-9090 an* 
 
APPENDIX. 
 
 693 
 
 By Rule 2. 
 
 355 : 113 : : 50 : 15-f4 
 50 
 
 355 5650 
 71 1130 (15‘9155 
 
 420 
 650 
 
 By Rule 3 • 
 
 3-1416 : 1 : : 50 : 15-9156 
 50 
 
 3-1416)50-000 (15-9156 
 
 ) 18584 
 
 2876 
 
 49 
 
 110 18 
 
 390 2 
 
 350 
 
 Proh. 10. To find the Length of any Arc of a Circle. 
 
 Rule 1, As 180 is to the number of degrees in the arc. 
 
 So is 3-1416 times the radius, to its length. 
 
 Or as 3 is to the number of degrees in the arc. 
 
 So is *05236 times the radius, to its length. 
 
 Ex. 1 . To find the length of an arc ADB (Prob. 8,) of 30 degrees, 
 the radius being 9 feet., 
 
 3*1416 
 
 9 
 
 As 180 : 30 
 
 dr 6 : 1 : : 282744 : 4-7124 
 Or 3: 30 : : *05236 x 9:4*7124 
 90 
 
 47124 the answer. 
 
 Rule 2. From 8 times the chord of half the arc subtract the 
 chord of the whole arc, and ^ of the remainder will be the length of 
 the arc nearly. 
 
 Ex. 2. The chord AB (Prob. 8.) of the whole arc being 4*65874, 
 and the chord AD of the half arc 2*34947 j required the length of 
 the arc. 
 
 2-34947 
 
 8 . 
 
 18-79576 
 
 4-65874 
 
 3 ) 14-13702 
 
 4*71234 answer. 
 
694 
 
 APPENDIX. 
 
 Prol, 11. To find the Area of a Circle, the diameter or circum- 
 ference being given. 
 
 Rule 1. Multiply half the circumference by half the diameter. 
 Or^ take J of the product of the whole circumference and diameter. 
 Rule 2. Multiply the square of the diameter by *7854. 
 
 Rule 3. Multiply the square of the circumference by ’07958. 
 Rule 4. As 14 is to 11, so is the square of the diameter to the 
 area. 
 
 Rule 5 . As 88 is to 7, so is the square of the circumference to the 
 
 area. 
 
 JS<r. To find the area of a circle whose diameter is 10, and cir- 
 cumference 314*159265 
 
 By Rule 1. 
 31-4159265 
 10 
 
 4)314-159265 
 area 78’53§816 
 
 By Rule 2. 
 
 •7854 
 
 100 
 
 area 78*54 
 
 By Rule 4. 
 
 14: 11 : : 100 
 
 1 1 area 
 
 14 
 
 1100 
 
 98 
 
 78*57 
 
 120 
 
 112 
 
 80 
 
 70 
 
 100 
 
 98 
 
 By Rule 3, 
 sq. circ. 986 96044 
 invert. 85970 
 “6908723 
 888264 
 49348 
 7896 
 
 78*54231 area. 
 
 2 
 
 By Rule 5. 
 31-4159265 circum. 
 562951413 invert, 
 94247779 
 3141593 
 1256637 
 31416 
 15708 
 2827 
 63 
 19 
 2 
 
 88:7:: 986*96044 
 7 
 
 8 
 
 11 
 
 6908-72308 
 
 863*59038 
 
 78*50821 
 
APPENDIX 
 
 695 
 
 Prol, 12. To find the Area of the Sector of a Circle. 
 
 Rule\. Multiply the radius, or half the diameter, by half the 
 arc of the sector, for the area. Or take J of the product of the dia- 
 meter and arc of the sector. 
 
 Note, The arc may be found by problem 10. 
 
 Rule 2. As 360 is to the degrees in the arc of the sector, so is 
 the whole area of the circle, to the area of the sector. 
 
 Ex. What is the area of the sector CAB, the radius being 10, and 
 the chord AB 1 6. 
 
 100=AC2 
 
 61=AE* 
 
 36 (6=CE 
 10=CD 
 
 4=DE 
 
 16=DE* 
 
 64=AE» 
 
 80 (8-94427l9=AD. 
 8 
 
 ^ 715541752 
 
 ' 16 
 
 3 ) 55-5541752 
 
 2 ) 18-5180584 arc ADB 
 
 9*2590297 = half arc 
 10 = radius 
 
 92-590297 answer. 
 
 Prol. 13. To find the Area of a Segment of a Circle. 
 
 Rule. Find the area of the sector having the same arc with the 
 segment, by the last problem. 
 
 Find the area of the triangle, formed by the chord of the segment 
 and the two radii of the sector. 
 
 Then the sum of these two will be the answer when the segment is 
 greater than a semicircle : but the difference will be the answer 
 when it is less than a semicircle. 
 
appendix. 
 
 606 
 
 Ex, Required the area of the segment ACBD, its chord AB being 
 12, and the radius EA or CE 10. 
 
 100 AE» 
 
 36 AD* 
 
 64 DE* 
 
 its root 8 DE 
 from 1 0 CE 
 
 2 CD 
 
 4 CD’ 
 
 36 AD’ 
 
 6 AD 
 8 DE 
 
 48 area of A EAB 
 
 50’596440 
 
 12 * 
 
 3)38-59644 j 
 
 2)12-86548 arc ACB 
 
 6-43274 i arc 
 10 radius 
 
 64 3274 area of sect. EACB 
 48-0000 area of triangle EAB 
 
 ans. 16‘3274 area of segm. ACBA 
 
 Prob. 14. To find the Area of a Circular Zone ADCBA. 
 
 Rule 1. Find the areas of the two segments AEB, DEC, and their 
 difference will be the zone ADCB. 
 
 Rule 2. To the area of the trapezoid DQP add the area of the 
 small segment ADRj and double the sum for the area of the zone 
 ADCB. 
 
 Prob. 15. To find the Area of a Circular Ring, or Space included 
 between two Concentric Circles. 
 
 The difference between the two circles will be the ring. Or, mul- 
 tiply the sum of the diameters by their difference, and multiply the 
 product by ’7854 for the answer. 
 
 Ex. The diameters of the two concentric circles being AB 10 
 
 40 chord AC’ 
 
 its root 6*324555 chord AC 
 8 
 
APPEND I -V. ^ 697 
 
 and DG 6, required tlie area of tlie ring containea between their 
 circumferences AEBA^ and BFGD. 
 
 10 
 
 •7854 
 
 6 
 
 64 
 
 sam 16 
 
 31416 
 
 dif. 4 
 
 47124 
 
 64 50*2656 Ansr. 
 
 Proh. 16. To measure long Irregular Figures. 
 
 ^ Take the breadth in several places at equal distances. Add all 
 the breadths together,, and divide the sum by the number of them, 
 for the mean breadth j which multiply by the length for the area. 
 
 Ex, The breadths of an irregular 6gure, at five equi -distant 
 places being AD 81, mP 7*4, nq 9 2, or 10*1, BC 8*6 5 and the 
 length AB 39 5 required the area. 
 
 8-1 
 
 7*4 
 
 9*2 
 
 10*1 
 
 5) 43*4 
 
 8-68 
 
 39 
 
 7812 
 
 2604 
 
 338*52 Ansr. 
 
 MENSURATION OF SOLIDS. 
 
 Proh, 1 . To find the Solidity of a Cube. 
 
 Cube one of its sides for the contents 5 that is, multiply the side 
 by itself, and that product by the side again. 
 
698 
 
 APPENDIX 
 
 Ex, If the side of a cube be 24 inches, what is its solidity or contents » 
 24 
 24 
 
 96 
 
 48 
 
 576 
 
 24 
 
 2304 
 
 1152 
 
 13824 Ansr. 
 
 Proh, 2, To find the Solidity of a Parallelopipedon. 
 
 Multiply the length by the breadth, and the products by the depth 
 or altitude. 
 
 Ex. Required the contents of the parallelopipedon whose length 
 AB is 6, its breadth AC 2, and altitude BD 3. 
 
 6 
 
 2 
 
 12 
 
 3 
 
 36 Ansr. 
 
 Proh. 3. To find the Solidity of any Prism. 
 
 Multiply the area of the base, or end, by the height, and it will 
 give the contents. 
 
 Which rule will do, whether the prism be triangular or square, or 
 pentagonal, &c. or round, as a cylinder. 
 
 Ex. What is the content of a triangular prism, whose length is 
 12, and each side of its equilateral base 8 } 
 
 Area of base, 28 X 12=336 contents. 
 
 Proh. 4. To find the Convex Surface of a Cylinder. 
 
 Multiply the circumference by the height of the cylinder. 
 
 Prob. 5. To find the Convex Surface of a Right Cone. 
 
 Multiply the circumference of the base by the slant height, or 
 length of the side, and half the product will be the surface. 
 
 Ex. If the diameter of the base be 5 feet,' and the side of the 
 cone 1 8, required the convex surface. 
 
 3T416 
 5 
 
 15*7080 circumf. 
 
 18 
 
 125664 
 
 15708 
 
 2 ) 282*744 
 
. APPENDIX. 
 
 699 
 
 
 Prob. 6 , To find the Convex Surface of the Frustum of a Right Cone. 
 Multiply the sum of the perimeters of the two ends by the slant 
 j height or side of the frustum, and half the product will be the surface. 
 
 Ex. If the circumferences of the two ends be 12*5 and 10'3, and 
 ; the slant height 14, required the convex surface of the frustum. 
 
 12-5 
 
 j 10-3 
 
 22-8 
 
 14 
 
 : 912 
 
 228 
 
 I 2 ) 319’2 
 
 i 159’6 Ansr. 
 
 Proh. 7. To find the Solidity of a Cone, or any Pyramid. 
 
 Multiply the area of the base by the perpendicular height of the 
 area, and one-third of the product will be the contents. 
 
 Proh. 8 . To find the Solidity of any Frustum of a Cone or Pyramid. 
 
 Rule. Add together the area of the base, the area of the upper 
 surface, and the mean proportional between those areas 3 take one- 
 third of this sum for the mean area, which multiplied by the height 
 will give the contents.— Or, for a cone, take the square of each dia- 
 meter of the base and upper surface, and the product of these two di- 
 ameters multiplied together 3 add these three sums together, and 
 multiply by *2618 for the mean area, which multiply as before. 
 
 Or, if the circumferences be used in like manner, instead of their 
 diameters, the multiplier will be *02654. 
 
 Ex. What is the content of the frustum of a cone, whose heighi 
 is 20 inches, and the diameters of its two ends 28 and 20 inches ? 
 Area of base 615*79 
 
 Area of upper surface 314*16 
 Mean proportional 439*84 
 
 3 ) 1369*79 
 
 456-59 
 
 20 
 
 9131-80 
 
 28 
 
 28 
 
 20 
 
 28 
 
 20 
 
 20 
 
 224 
 
 560 
 
 40f 
 
 56 
 
 784 
 
 _ 
 
 _ 
 
 400 
 
 
 784 
 
 
 
 — 
 
 1744 
 
 
 
 2618 
 
 
 
 13952 
 
 
 1744 
 
 10464 
 
 3488 
 
 456-5792 
 20 
 
 9131*5840 Ansr. 
 
APPENDIX. 
 
 700 
 
 Proh. 9. To find the Solidity of a Wedge. 
 
 To the length of the edge add twice the length of the back or base, 
 and reserve the sum j multiply the height of the wedge by the 
 breadth of the base j then multiply this product by the reserved sum, 
 and one-sixth of the last product will be the contents. 
 
 E<r. What is the contents of a wedge, whose altitude AP is J 1 
 inches, its edge AB 21 inches, and the length of its base DE 32 
 inches, and its breadth CD 4^ inches ? 
 
 21 
 
 14 
 
 32 
 
 
 32 
 
 — 
 
 — 
 
 56 
 
 85 
 
 7 
 
 
 63 
 
 
 85 
 
 
 315 
 
 
 504 
 
 6 ! 
 
 1 5355 
 
 I 892’5 Ansr. 
 
 Proh. 10. To find the Solidity of a Prismoid. 
 
 Definition . — A prismoid differs only from the frustum of a pyramid, 
 in not having its opposite ends similar planes. 
 
 Rule. Add into one sum, the areas of the two ends and four times 
 the middle section parallel to them, and one-sixth of that sura will be 
 a mean area j and being multiplied by the height, will give the 
 contents. 
 
 Note . — ^The length of the middle section is equal to half the sum 
 of the lengths of the two ends j and its breadth is equal to half the 
 sum of the breadths of the two ends. 
 
 Ex. What are the contents of a prismoid whose ends are rec- 
 tangles, the length and breadth of the one being 14 and 12 ; and 
 the corresponding sides of the other 6 and 4, the perpendicular height 
 being 30^ ? 
 
 14 10 6 
 
 12 8 4 
 
 • 168 80 24 
 
 320 
 
 168 
 
 24 
 
 6 ) 512 
 
APPENDIX. 
 
 701 
 
 Sft-^Ninean area. 
 30^ height. 
 
 2560 
 
 2602*6 Ansr. 
 
 Proh* 1 J . To find the Convex Surface of a Sphere or G^obe. 
 
 Multiply its diameter by its circumference. 
 
 Note . — In like manner the convex surface of any zone or segment 
 is found, by multiplying its height by the whole circumference of the 
 sphere. 
 
 Ex. Required the convex superficies of a globe, whose diameter 
 or axis is 24. 
 
 3*1416 
 
 24 diam, . 
 
 125664 
 
 62832 
 
 75-3984 circumf. 
 24 
 
 3015936 
 
 1507968 
 
 1809*5616 Ansr. 
 
 Prob. 12, To find the Solidity of a Sphere or Globe. 
 Multiply the cube of the axis by *5236. 
 
 Ex. What is the solidity of the sphere, whose axis is 12 > 
 12 
 12 
 
 144 
 
 12 
 
 1728 ' 
 
 < *5236 
 
 10368 
 
 5184 
 
 3456 
 
 8640 
 
 904-7808 Ansr. 
 
APPENDIX. 
 
 702 
 
 Proh. 13. To find the Solidity of a Spherical Segment. 
 
 To 3 times the square of the radius of its base add the square of its 
 height ; then multiply the sum by the height, and the product again 
 by *5236. 
 
 Ex, Required the contents of a spherical segment, its height 
 AB being 4, and the radius of its base CD 8. 
 
 8 
 
 4 
 
 •5236 
 
 8 
 
 A 
 
 832 
 
 64 
 
 16 
 
 10472 
 
 3 
 
 192 
 
 15708 
 
 192 
 
 208 
 
 4 
 
 41888 
 
 435*6352 Ansi' 
 
 
 832 
 
 
 Proh. 14. To find the Solidity of a Spherical Zone or Frustum. 
 
 Add together the square of the radius of each end and of the 
 square of their distance, or the height j then multiply the sum by 
 the said height, aud the product again by T5708. 
 
 Ex. What is the solid contents of a zone, whose gi'eater diame- 
 ter is 12, the less 8, and the height 10 inches ? 
 
 4 10 
 
 4 10 
 
 IG 3) 100 
 
 36 
 
 33t 33 ]- ' 
 
 1*5708 
 
 78540 
 
 125664 
 
 5236 
 
 •0416 
 
 10 
 
 1340*416 Ansr. 
 
 Proh. 15. To find tiie Surface of a (nrcular Spindle. 
 
 Multiply the length AB of the spindle by the radius OC of the re- 
 volving arc. Multiply also the said arc ACB by the central dis- 
 tance OS, or distance betv/een the centre of the spindle and centre 
 of the revolving arc. Subtract the latter product from the former, 
 and multiply the remainder by 6*2832, for the surface. 
 
 Note. I'he same rule will serve for any segment or zone cut off 
 perpendicular to the chord of the revolving arc, only using the par- 
 
 6 
 
 6 
 
 36 
 
APPENDIX. 703 
 
 ticular length of the part, and the part of the arc which describes it, 
 instead of the whole length and whole arc. 
 
 Ex. Required the surface of a circular spindle, whose length 
 AB is 40, and its thickness CD 30 inches. 
 
 Here, by the rema rks at pa. 68 8. 
 
 The chord AC = v/ AE'^ + CE'^ = V 20^ + 15" = 25, 
 and 2 CE : AC : : AC : CO =20^, 
 
 hence OE = OC — CE = 20-|- — 15 = 5-g-. 
 
 Also, by problem 10, rule 2, pa. 693 
 25 AC 
 8 
 
 200 
 40 AB 
 
 3) 160 
 
 53'5' arc ACB 
 
 Then 
 
 ij by our rule. 
 
 20A 
 
 531- 
 
 40 
 
 3-f 
 
 — 
 
 — 
 
 *800 
 
 266-i- 
 
 33i 
 
 44-1 
 
 — 
 
 
 833+ 
 
 311i 
 
 311-h 
 
 522-1 
 
 or 522-2 or ^ 
 
 6-2832 
 
 Or thus, 
 6-2832 
 
 10444 
 
 4700 
 
 156666 
 
 — — 
 
 41/7777 
 
 439824 
 
 10444444 
 
 251328 
 
 313333333 
 
 
 3281-22666 
 
 9 ) 29531-04 
 
 328T226 ans. nearly 
 
 Prob. 16. To find the Solidity of a Circular Spindle. 
 
 Multiply the central distance OE by half the area of the reveling 
 segment ACBEA. Subtract the product from of the cube of EA, 
 half the length of the spindle. Then multiply the remainder by 
 12-5664, or 4 times 3*1 41 6, for the whole contents 
 
APPENDIX. 
 
 704 
 
 Ex, Required the contents of the circular spindle, whose length 
 AB is 40, and middle diameter CD 30. 
 
 By the work of the last problem. 
 
 we have OE = 6|^ 
 
 20 half length 
 
 and arc AC = 26-|. 
 
 20 
 
 and rad. OC = 20^ 
 
 
 — ■ 
 
 400 
 
 533-^ 
 
 20 
 
 22-1- 
 
 — 
 
 
 
 3 ) 8000 
 
 Sector OACB 355i 
 
 AE X OE=OAB l)6f 
 
 26664. 
 
 — 
 
 12804 
 
 2 ) 438-1- 
 
 — 
 
 1386-J. 
 
 seg, ACE 2194 — ■ ■■■ 
 
 OE 51 
 
 or 1386-44 
 
 4665*21 mult, inver. 
 
 10974 
 
 183 nearly 
 
 138644 
 
 — 
 
 27739 
 
 128 O 4 
 
 ^ 6-932; 
 
 832 
 83 
 
 
 5 
 
 ' 17423*5 Ansr. 
 
 Proh. 17 . To find the Solidity of the Middle Frustum ' 
 
 of a Circular Spindle. 
 
 From the square of half the length of the whole spindle, take ^ 
 of the square of half the length of the middle frustum, and multiply 
 
 the remainder by the said half length of the frustum. Multiply 
 
 the central distance by the revolving area, which generates the mid- 
 dle frustum. — Subtract this latter product from the former j and the 
 remainder multiplied by i6’2832, or twice 3*1416, will give the 
 contents. ' 
 
 Ex. Required the solidity of the frustum, whose length m n is 
 40 inches, also its greatest diameter EF is 32, and least diameter 
 AD or BC 24. 
 
 Draw DG parallel to m n, then we- 
 have DG = -|m n = 20, 
 
APPENDIX. 
 
 705 
 
 and EG = ^EF - |AD = 4, 
 chord DE2= DG^ + GE^ = 416, 
 
 and DE2 -f- EG = ii?= 104 the diameter of the generating 
 
 circle. 
 
 or the radius OE = 52, 
 
 hence 01 =: 52 — 16 = 36 the central distance, 
 and HP = OH^ ^ OP = 52^- 36^ = 1408, 
 JDG®=iof400 = .. .. 133-^, 
 
 12741 
 
 DG .. .. 20 
 
 25493-5- 
 
 1st. prod. 
 
 GE 2 OE = _1_= —= *03846 a ver. sine 
 104 26 
 
 Its tab. segment , . *00994 
 
 butl042 is .. 10816 
 
 nrea of seg. DECGD 1D7*5 1 104 
 
 m D X mn = 12 X 40 480* 
 
 gener. area m DEC n 587*5 1 104 
 
 01 36 
 
 21150*39744 2d product 
 25493*33333 1st product 
 
 4342*93589 
 2382*6 mult. inv. 
 
 260576 
 
 8686 
 
 3474 
 
 130 
 
 9 
 
 27287*5 Ansr. 
 
 Proh. 18. To find the Superficies or Solidity of any Regular Body. 
 
 1, Multiply the tabular area (taken from the following table) by 
 the squ^are of the linear edge of the body for the superficies. 
 
 2. Multiply the tabular solidity by the cube of the linear edge, 
 for the solid contents. 
 
706 
 
 APPENDIX. 
 
 Surfaces and Solidities of Regular Bodies. 
 
 No. of 
 Sides 
 
 Names 
 
 Surfaces 
 
 Solidities 
 
 4 
 
 Tetraedron 
 
 1*73205 
 
 0*11785 
 
 6 
 
 Hexaedron 
 
 600000 
 
 1*00000 
 
 8 
 
 Octaedron 
 
 3*46410 
 
 0*47140 
 
 12 
 
 Dodecaedron 
 
 20 64573 
 
 7*66312 
 
 20 
 
 leosaedron 
 
 8'660*2o 
 
 2*18169 
 
 Ex, If the linear edge or side of a tetraedron be 3, required its 
 surface and solidity. 
 
 The square of 3 is 9, and the cube 27,. Then, 
 tab. sur. T73205 0T1785 tab. sol. 
 
 9 27 
 
 superf. 15'58845 8249.5 
 
 23570 
 
 solidity 3' 18 195 
 
 Proh, 19. To find the Surface of a Cylindrical Ring. 
 
 This figure being only a cylinder bent round into a ring, its surface 
 and solidity may be found as in the cylinder, namely, by multiplying 
 the axis, or length of the cylinder, by the circumference of the ring 
 or section, for the surface j and by the area of a section, for the so- 
 lidity. Or use the following rules : 
 
 For the surface. To the thickness of the ring add the inner 
 
 diameter j multiply this sum by the thickness, and the product again 
 by 9 8696, or the square of 3*1416. 
 
 Ex. Required the superficies of a ring, whose thickness AB is 2 
 inches, and inner diameter BC is 12 inches. 
 
 12 
 
 9*8696 
 
 2 
 
 28 
 
 14 
 
 789568 
 
 2 
 
 197392 
 
 28 
 
 276*3488 
 
 Prob. 20. To find the Solidity of a Cylindrical Ring. 
 
 To the thickness of the ring add the inner diameter j then multiply 
 the sum by the square of the thickness, and the product again by 
 2*4674, or J of the square of 3*1416, for the solidity. 
 
 Ex. Required the solidity of the ring whose thickness is 2 inches, 
 and its inner diameter 12. 
 
 12 2*4674 
 
 2 56 
 
 14 148044 
 
 4 123370 
 
 138*1744 Ansr. 
 
 56 
 
USEFUL RECEIPTS. 
 
 Compounds of Metals, 
 
 Fusible ik/e/a/.— No. 1. 
 
 4 oz. of bismuth, 
 
 2| oz. of lead, and 
 1 J oz. of tin. 
 
 Put the bismuth into a crucible, and, when it is melted, add the lead 
 and tin. This will form an alloy fusible at the temperature of boiling 
 water. 
 
 No. 2.— 1 oz. of zinc, 
 
 1 oz. of bismuth, and 
 
 1 oz. of lead. 
 
 This alloy is so very fusible, that it will remain in a state of fusion if 
 put on a sheet of paper, and held over the flame of a candle or lamp. 
 No. 3. — —3 parts of- lead, 
 
 2 parts of tin, and 
 
 5 parts of bismuth, 
 
 will form an alloy fusible at 197° Fahrenheit, peculiarly applicable 
 to casting, or the taking of impressions from gems, seals, &c. In 
 making casts with this and similar alloys, it is necessary to use the 
 metal at as low a temperature as possible ; otherwise, the w'ater ad- 
 hering to the things from which the casts are to be taken, forms 
 vapour, and produces bubbles. The fused metal should be poured 
 into a tea cup, and allowed to cool, till just ready to set at the edges, 
 when it must be poured into the mould. In taking impressions from 
 gems, seals, &c. the fused alloy should be placed on paper or paste- 
 board, and stirred about till it has, by cooling, attained the consis- 
 tence of paste, at which moment the die, gem, or seal should be 
 stamped on it, and a very sharp impression will then be obtained. 
 Bath Metal, is a mixture of 
 
 4^ oz, of zinc, with 
 1 lb. of brass. 
 
 Brass is composed of 
 
 4i lb. of copper, and 
 1^’lb. of zinc. 
 
 But brass that is to be cast into plates, from which pans and kettles 
 are to be made, and wire is to be drawm, must, instead of using the 
 zinc in a pure state, be composed of 
 
 56 lb. of the finest calamine, or ore of zinc, and 
 34 lb. of copper. 
 
 2 Z2 
 
APPENDIX. 
 
 708 
 
 Old brasSj which has been frequently exposed to the action of fire, 
 when mixed with the copper and calamine, renders the brass far more 
 ductile, and fitter for the making of fine wire, than it would be with- 
 out it 3 but the German brass, particularly that of Nuremburgh, is, 
 when drawn into wire, said to be far preferable to any made in Eng- 
 land, for the strings of musical instruments. 
 
 Pinchbeck.— '^0. 1 . 
 
 5 oz. of pure copper, and 
 
 1 oz. of zinc. 
 
 The zinc must not be added till the copper is in a state of fusic 
 Some use only half this quantity of zinc, in which proportion the 
 alloy is more easily worked, especially in the making of jewellery. 
 
 No. 2. 1 oz. of brass, 
 
 2 oz. of copper, 
 
 Fused together, under a coat of charcoal dust. 
 
 Prince s Metal. — No. 1 . 
 
 3 oz. of copper, and 
 1 oz. of zinc. 
 
 Or, 8 oz. of brass, and 
 
 1 oz. of zinc. 
 
 No. 2 . -4 oz. of copper, and 
 
 2 oz. of zinc. 
 
 In this last, the copper must be fused before the zinc is added. 
 When they have cotnbined, a very beautiful and useful alloy is formed, 
 called Prince Rupert’s metal. 
 
 Bell Metal. — No. 1. 
 
 6 parts of copper, and 
 2 parts of tin. 
 
 These proportions are the most approved, for bells, throughout Eu- 
 rope, and in China. In the union of the two metals, the combination 
 is so complete, that the specific gravity of the alloy is greater than 
 that of the two metals in an uncombined state. 
 
 No. 2.— — 10 parts of copper, and 
 2 parts of tin. 
 
 It may, in general, be observed, that a less proportion of tin is 
 used for making church-bells than clock bells 3 and that a little zinc 
 is added for the bells of repeating watches, and other small bells. 
 
 Tiitania, or Britannia Metal. — No. 1. 
 
 4 oz. of plate brass, and 
 
 4 oz. of tin 5 when in fusion, add 
 4 oz. of bismuth, and 
 4 oz. of regulus of antimony. 
 
 This is the composition, or hardening, that is to be added, at dis- 
 cretion, to melted tin, until it has acquired the requisite degree of 
 colour and hardness. 
 
 No. 2 . — Melt together, 2 lb. of plate brass. 
 
 2 lb. of tin. 
 
APPENDIX. 
 
 709 
 
 2 lb. of bismuth, 
 
 2 lb. regulus of autimory,* 
 
 2 lb. of a mixture of copper and arsenic, 
 either by cementation or melting. 
 
 '^his composition is to be added, at discretion, to melted tin. 
 
 No. 3. 1 lb. of copper, 
 
 , 1 lb. of tin, and 
 
 2 lb. of regulus of antimony, with or without a 
 little bismuth. 
 
 No. 4. 8 oz. of shruff brass, 
 
 2 lb. regulus of antimony, and 
 10 lb. of tin. 
 
 German Tutania. 
 
 2 drachms of copper, 
 
 1 oz. regulus of antimony, and 
 12 oz. of tin. 
 
 Stanish Tutania, — No. 1. 
 
 8 oz. of scrap iron or steel, 
 
 1 lb. of antimony, and 
 
 3 oz. of nitre. 
 
 The iron or steel must be heated to a white heat, and the antimony 
 and nitre must be added in small portions. Melt and harden 1 lb. of 
 tin with 2 oz. of this compound. 
 
 No. 2. — Melt together, 4 oz. of antimony, 
 
 1 oz. of arsenic, and 
 
 2 lb. of tin. 
 
 The first of these Spanish alloys would be a beautiful if ar- 
 
 senic were added. 
 
 Engestroom Tutania. 
 
 4 parts copper, 
 
 8 parts regulus of antimony, and 
 1 part bismuth, ’ 
 
 When added to 100 parts of tin, this compound will be ready for use. 
 
 Queens Metal. — No. 1. 
 
 4i lb. of tin, 
 
 ■§ lb. bismuth, 
 i lb. antimony, and 
 i lb. lead. 
 
 This alloy is used for the making of tea-pots, and other vessels, 
 which are required to imitate silver. It retains its lustre to the last. 
 
 No. 2. 100 lb. of tin, 
 
 8 lb. regulus of antimony, 
 
 1 lb. bismuth, and 
 4 lb, copper. 
 
APPENDIX. 
 
 710 
 
 IVUte Me/a/.— No. 1. 
 
 10 oz. of lead, 
 
 6 oz. of bismuth, and 
 
 4 drachms regulus of antimony. 
 
 No. 2.- 2 Ib. of regulus of antimony, 
 
 8 oz. of brass, and 
 10 oz. of tin. 
 
 Common Hard White Metal. 
 
 1 lb. of brass, 
 
 1^ oz. of zinc, and 
 i oz. of tin. 
 
 Tombac, 16 lb. of copper, 
 
 1 lb. of tin, and 
 1 lb. of zinc. 
 
 Red Tombac, 5| lb. of copper, and 
 
 i lb. of zinc. 
 
 The copper must be fused in the crucible before the zinc is added. 
 This alloy is of a reddish colour, and possesses more lustre, and is of 
 greater durability, than copper. 
 
 White Tombac, Copper and 
 
 Arsenic, 
 
 *ut together in a crucible, and melted, covering the surface with mu- 
 riate of soda, to prevent oxidation, will form a white brittle alloy. 
 
 Gun Metal, — No. 1 . 1 12 lb. of Bristol brass, 
 
 14 lb. zinc, and 
 7 lb. block tin. 
 
 No. 2.— -9 parts copper, and 
 1 part tin. 
 
 The above compounds are those used in the manufaetHre of small 
 and great brass guns, swivels, &c. 
 
 Blanched Copper, 8 oz. of copper, and 
 
 i oz. of neutral arsenical salt, 
 
 fused together, under a flux composed of calcined borax, charcoal 
 dust, and fine powder glass. 
 
 Specula of Telescopes. 
 
 7 lb. of copper, and when fused, add 
 
 3 lb. of zinc, and 
 
 4 lb. of tin. 
 
 'i hese metals will combine and form a beautiful alloy of great lustre, 
 and of a light yellow colour, fitted to be made into specula for teles- 
 copes. Mr. Mudge used only copper and grain tin, in the proportion 
 of two pounds to fourteen and a half ounces. 
 
 Kustitiens Metal for Tinning. 
 
 To 1 lb. of malleable iron, at a white heat, add 
 
APPENDIX. 
 
 711 
 
 5 oz. of regulus of antimony, and 
 24 lb. of the purest Molucca tin. 
 
 This alloy polishes without the blue tint, and is free from lead or 
 arsenic. 
 
 Metal for Flute-key Valves. 
 
 4 oz. lead, and 
 2 oz. antimony, 
 
 fused in a crucible, and cast into a bar, forms an alloy of considerable 
 hardness and lustre. It is used by flute manufacturers (when turned 
 into small buttons in a lathe,) for making valves to stop the key- 
 holes of flutes. 
 
 Printers' Types. 10 lb. of lead, and 
 2 lb. of antimony. 
 
 The antimony must be thrown into the crucible when the lead is in 
 a state of fusion. The antimony gives a hardness to the lead, without 
 which, the type would speedily be rendered useless, in a printing 
 press. Different proportions of lead, copper, brass, and antimony, 
 frequently constitute this metal. Every artist has his own propor- 
 tions, so that the same composition cannot be obtained from different 
 foundries ; each boasts of the superiority of his own mixture. 
 
 Small Types and Stereotype Plates.— No. 1 . 
 
 9 lb. of lead, and when melted, add 
 2 lb. of antimony, and 
 
 1 lb. of bismuth. 
 
 This alloy expands as it cools, and is, therefore, well suited for the 
 formation of small printing types, (particularly when nmny are cast 
 together, to form stereotype plates,) as the whole of the mould is 
 accurately filled with the alloy ) consequently, there can be no ble- 
 mish in the letters. 
 
 No. 2. 8 parts lead, 
 
 2 parts antimony, and 
 J part tin. 
 
 For the manufacture of stereotype plates, plaster of Paris, of the 
 consistence of a batter pudding before baking, is poured over the let- 
 ter-press page, and u'orked into the interstices of the types, with a 
 brush. It is then collected from the sides, by a slip of iron or wood, 
 so as to lie smooth and compact. In about two minutes, the whole 
 mass is hardened into a solid cake. This cake, w^hich is to serve as 
 the matrix of the stereotype plate, is now put upon a rack in an oven, 
 where it undergoes great heat, so as to drive off superfluous moisture. 
 When ready for use, these moulds, according to their size, are placed 
 in flat cast-iron pots, and are covered over with another piece of 
 cast-iron, perforated at each end, to admit the metallic composition 
 intended for the preparation of the stereotype plates. The flat cast- 
 iron pots are now fastened in a crane, which carries them steadily to 
 the metallic-bath, or melting-pot, where they are immersed, and 
 kept for a considerable time, until all the pores and crevices of the 
 mould, are completely and accurately filled. When this has taken 
 place, the pots are elevated from the bath, by working the crane, and 
 
APPENDIX. 
 
 712 
 
 are placed over a water-troiTgh, to cool graaually. wnen cold, tu^ 
 whole is turned out of the pots, and the plaster being separated, by 
 hammering and washing, the plates are ready for use, having received 
 the most exact and perfect impression. 
 
 Metallic Casts from Engravings on Copper. 
 
 A most important discovery has lately been made, which promises 
 to be of considerable utility in the fine arts : some very beautiful 
 specimens of metallic plates, of a peculiar composition, have lately 
 appeared, under the nam# of cast engravings.” This invention 
 consists in taking moulds from every kind of engravings, with line, 
 mezzotinto, or aquatinta, and pouring on this mould an alloy, in a 
 state of fusion, capable of taking the finest impression. The obvious 
 utility of this invention, as applicable to engravings which meet with 
 a ready sale, and of which great numbers are required, will be incal- 
 culable as it will wholly prevent the expense of retracing, which 
 forms so prominent a charge in all works of an extended sale. No 
 sooner is one cast worn out, than another may be immediately pro- 
 cured from the original plate, so that every impression will be a 
 proof. Thus, the works of our most celebrated artists may be handed 
 down, ad infinitum^ for the improvement and delight of future ages, 
 and will alford,^at the same time, the greatest satisfaction to every 
 lover of the fine arts. 
 
 Common Pewter. 7 lb. of tin, 
 
 1 lb, of lead, 
 
 6 oz, of copper, and 
 
 2 oz. of zinc. 
 
 The copper must be fused before the other ingredients are added. 
 This combination of metals will foFm an alloy of great durability and 
 tenacity ; also, of considerable lustre. 
 
 Best Pewter. 100 parts tin, and 
 
 17 parts regulus of antimony. 
 
 Hard Pewter. 12 lb. of tin, 
 
 1 lb. regulus of antimony, and 
 
 4 oz. of copper. 
 
 Common Solder. 2 lb. of lead, and 
 
 1 lb. of tin. 
 
 'Hie lead must be melted before the tin is added. This alloy, when 
 heated by a hot iron, and applied to the tinned iron with powdered rosin, 
 acts as a cement or solder j it is also used to join lead pipes, &c. &c. 
 
 Soft Solder, 2 lb. of tin, and 
 
 1 lb. of lead. 
 
 Solder for Steel Joints. 
 
 19 dwts, of fine silver, 
 
 1 dwt. copper, and 
 
 2 dwts. brass. 
 
APPENDIX. 
 
 713 
 
 melted together under a coat of charcoal dust. This solder possesses 
 several advantages over the usual zinc soda, or brass, when employed 
 in soldering cast steel, &c. as it fuses with less heat, and its white- 
 ness has a better appearance than brass. 
 
 Silver Solder for Jewellers* 
 
 19 dwts. of fine silver, 
 
 1 dwt. copper, and 
 10 dwts. brass. 
 
 Silver Solder for Plating* 
 
 10 dwts. brass, and 
 
 1 oz. pure silver. 
 
 Gold Solder. 12 dwts. pure gold, 
 
 2 dwts. pure silver, and 
 4 dwts. copper. 
 
 Brass Solder for Iron. — Thin plates of brass are to be melted be- 
 tween the pieces that are to be joined. If the work be very fine, 
 as when two leaves of a broken saw are to be brazed together, cover 
 it with pulverized borax, melted with water, that it may incorporate 
 with the brass powder, which is added to it ; the piece must be then 
 exposed to the fire, without touching the coals, and heated till the 
 brass is seen to run. 
 
 Bronze. 7 lbs. pure copper, 
 
 3 lbs. zinc, and 
 2 lbs. tin. 
 
 The copper must be fused before the other ingredients are added. 
 These metals, when combined, form the bronze so much used, both 
 in ancient and modern times, in the formation of busts, medals, and 
 statues. 
 
 Composition of ancient Statues. 
 
 According to Pliny, the metal used by the Romans for their sta- 
 tues, and for the plates on which they engraved inscriptions, was 
 composed in the following manner. They first melted a quantity of 
 copper, into which they put l-3d of its weight of old copper, which 
 had been long in use j to every lOOlbs. weight of this mixture, they 
 added 12-^ lbs. of an alloy composed of equal parts of lead and tin. 
 
 Mock Platina. — Melt together 
 
 8 oz. of brass, and 
 5 oz. of zinc. 
 
 Useful alloy of Gold with Platinum. 
 
 7-^ dr. pure gold, and 
 i dr. platinum. 
 
 The platinum must be added when the gold is perfectly melted. The 
 two metals will combine intimately, forming an alloy rather whiter 
 than pure gold, but remarkably ductile and elastic ; it is also less 
 
APPENDIX. 
 
 714 
 
 perishable than pure gold, or jeweller’s gold : but more readily fusible 
 than that metal. 
 
 These excellent qualities must render this alloy an object of great 
 interest to workers in metals. For where steel cannot be 
 
 used, it will prove exceedingly advantageous. 
 
 It is a curious circunsstance, that the alloy of gold and platinum is 
 soluble in nitric acid, which does not act on either of the metals in a 
 separate state. It is remarkable, too, that the alloy has very nearly 
 the colour of platinum, even when composed of eleven parts of gold to 
 one of the former metal. 
 
 Ring-gold, 6 dwts. 12 grs. Spanish copper, 
 
 3 dwts. 16 grs. fine silver, and 
 1 oz. 5 dwts. gold coin. 
 
 Gold from 35s. to 405. per ounce. 
 
 , 8 oz. 8 dwts. Spanish copper, 
 
 10 dwts. fine silver, and 
 1 oz. gold coin. 
 
 Manheim-goldi or Similor, 
 
 3-j oz. of copper, 
 
 1-|- oz. of brass, and 
 f 15 gr. of pure tin. 
 
 Gilding- Metal, 4 parts of copper, 
 
 1 part of Bristol old brass, and 
 14 oz. of tin to every pound of copper. 
 
 For common jewellery .3 parts of copper, 
 
 1 part of Bristol old brass, and 
 
 4 oz. of tin to every pound of copper. 
 
 If this alloy is for fine polishing, the tin may be omitted, and a mix- 
 ture of lead and antimony substituted. Paler polishing metal is 
 made by reducing the copper to two or to one part. 
 
 Yellow Dipping Metal. — -No 1. 
 
 2 parts of Cheadle brass, 
 
 I part of copper, with a little 
 Bristol old brass, and 
 T oz. of tin to every pound of copper., 
 
 This alloy is almost of the colour of gold coin. Cheadle brass is the 
 darkest, and gives the metal a greenish hue. Old Bristol brass is 
 pale and yellow. 
 
 No. 2. — 1 lb. of copper, and 
 
 5 oz. of zinc. 
 
 The copper should be tough cake, and not tile. 
 
 When antimony is used instead of tin, it should be in smaller 
 quantity, or the metal will be brittle. 
 
 Imitation of Silver. J oz. of tin, and 
 1 lb. of copper. 
 
 Will make a pale bell-metal, which will roll and ring very near to 
 sterling silver. 
 
APPENDIX. 
 
 715 
 
 PREPARATION OF FOILS. 
 
 Foils are thin plates or leaves of metal that are put under stones, 
 or compositions in imitation of stones, when they are set. 
 
 The intention of foils is either to increase the lustre or play of the 
 stones, or more generally improve the colour, by giving an additional 
 force to the tinge, whether it be natural or artificial, by that of a 
 ground of the same hue, which the foil is in this case made to be. 
 
 There are consequently two kinds of foils j the one is colourless, 
 where the eflfect of giving lustre or play to the stone is produced by 
 the polish of the surface, which makes it act as a mirror, and, by 
 reflecting the light, prevents that deadness which attends the having a 
 duller ground under the stone, and brings it, by the double refraction 
 of the light that is caused, nearer to the eflfect of the diamond. The 
 other is coloured with some pigment or stain of the same hue as the 
 stone, or of some other which is intended to modify and change the 
 hue of the stone in some degree j as, where a yellow foil may be put 
 under green, which is too much inclining to the blue, or under crimson, 
 where it is desired to have the appearance more orange or scarlet. 
 
 Foils may be made of copper or tin j and silver has been some- 
 times used, with which it has been advised, for some purposes, to 
 mix gold, but the expense of either is needless, as copper may be 
 made to answer the same end. 
 
 To prepare Copper for Where coloured foils are wanted, 
 
 copper may therefore be best used, and may be prepared for the 
 purpose by the following means. 
 
 Take copper plates beaten to a proper thickness, and pass them 
 betwixt a pair of fine steel rollers very close set, and draw them as 
 thin as is possible to retain a proper tenacity. Polish them with very 
 fine whiting, or rotten-stone, till they shine, and have as much 
 brightness as can be given them, and they will then be fit to receive 
 the colour. 
 
 To whiten Foi/^.— Where the yellow, or rather orange-colour of 
 the ground would be injurious to the eflfect, as in the case of pur- 
 ples, or crimson red, the foils should be whitened, which may be 
 done by the following manner. 
 
 Take a small quantity of silver, and dissolve it in aqua-fortis, and 
 then put bits of copper into the solution, and precipitate the silver 5 
 which being done, the fluid must be poured oflf, and fresh water 
 added to it, to wash away all the remainder of the first fluid j after 
 which the silver must be dried, an equal weight of cream of tartar and 
 common salt must then be ground with it, till the whole is reduced to 
 a very fine powder j and with this mixture the foils, being first slight- 
 ly moistened, must be rubbed by the finger, or a bit of linen rag, 
 till they be of the degree of whiteness desired ; after which, if it 
 appear to be wanted, the polish must be refreshed. 
 
 The tin-foils are only used in the case of colourless stones, where 
 
APPENDIX. 
 
 716 
 
 quicksilver is employed 3 and they may be drawn out by the same 
 rollers, but need not be further polished, so that effect is produced 
 by other means in this case. 
 
 Foils for crystals^ pebbles, or paste, to give the lustre and play of 
 diamonds.- — The manner of preparing foils, so as to give colourless 
 stones the greatest degree of play and lustre, is by raising so high a 
 polish or smoothness on the surface, as to give them the effect of a 
 mirror, which can only be done, in a perfect manner, by the use of 
 quicksilver, applied in the same general way as in the case of look- 
 ing-glass. The method by which it may be best performed is as follows. 
 
 Take leaves of tin, prepared in the same manner as for silvering 
 looldiig-glasses, and cut them into small pieces of such size as to 
 cover the surface of the sockets of the stones that are to be set. Lay 
 three of these then, one upon another, and having moistened the in- 
 side of the socket with thin gum -water, and suffered it to become 
 again so dry, that only a slight stickiness remains, put the three 
 pieces of leaves, lying on each other, into it, and adapt them to the 
 surface in as even a manner as possible. When this is done, heat the 
 socket, and fill it with warm quicksilver, which must be suffered to 
 continue in it three or four minutes, and then gently poured out. 
 The stone must then be thrust into the socket, and closed with it, 
 care having been taken to give such room for it that it may enter 
 without stripping off the tin and quicksilver from any part of the 
 surface. The work should be well closed round the stone, to pre- 
 vent the tin and quicksilver contained in the socket from being shaken 
 out by any violence. 
 
 The lustre of stones set in this manner, will continue longer than 
 when they are set in the common way, as the cavity round them 
 being filled, there will be no passage found for moisture, which is so 
 injurious to the wear of stones treated in any other way. 
 
 This kind of foil likewise gives some lustre to glass or other trans- 
 parent matter, which has little of itself ; but to stones or pastes, 
 that have some share of play, it gives a most beautiful brilliance. 
 
 To colour Foils. — Two methods have been invented for colouring 
 foils : the one by tinging the surface of the copper of the colour re- 
 quired by means of smoke, the other by staining or painting it with 
 some pigment or other colouring substance. 
 
 The colours used for painting foils may be tempered with either 
 oil, w^ater rendered duly viscid by gum-arabic, size, or varnish. 
 Where deep colours are wanted, oil is most proper, because some 
 pigments become wholly transparent in it, as lake, or Prussian blue j 
 the yellow and green may be better laid on in varnish, as these co- 
 lours may be had in perfection from a tinge wholly dissolved in spirit 
 of wine, in the same manner as in the case of lacquers j and the most 
 beautiful green is to be proiluced by distilled verdigris, which is apt 
 to lose its colour and turn black with oil. In common cases, how- 
 ever, any of the colours may be, with the least trouble, laid on with 
 isinglass size, in the same manner as the glazing colours used in 
 miniature painting. 
 
APPENDIX. 
 
 717 
 
 Ruby ’Colours , — For red, where the ruby is to be imitated, a little 
 lake used in isinglass size, carmine, or shell-lac varnish, is to be em- 
 ployed, if the glass or paste be of a full crimson, verging towards the 
 purple ; but if the glass incline to the scarlet, or orange, very bright 
 lake (that is, not purple) may be used alone in oil. 
 
 Garnet Red . — For the garnet red, dragon’s blood dissolved in seed- 
 lac varnish may be used 5 and for the vinegar garnet, the orange-lake 
 tempered with shell-lac varnish, will be found excellent. 
 
 Amethyst . — For the amethyst, lake, with a little Prussian blue, 
 used with oil, and very thinly spread on the foil, will completely an- 
 swer the end. 
 
 Blue . — For blue, where a deep colour, or the effect of the sapphire 
 is wanted, Prussian blue, that is not too deep, should be used in oil, 
 and it should be spread more or less thinly on the foil according to 
 the lightness or deepness of the colour required. 
 
 Eagle Marine . — For the eagle-marine, common verdigris, with a 
 little Prussian blue, tempered in shell-lac varnish. 
 
 Yellow . — Where a full yellow is desired, the foil may be coloured 
 with a yellow lacquer, laid on as for other purposes j and for the 
 slighter colour of topazes, the burnish and foil itself will be sufficiently 
 strong without any addition. 
 
 Green , — For green, where a deep hue is required, the crystals of 
 verdigris, tempered in shell-lac varnish, should be used, but where 
 the emerald is to be imitated, a little yellow lacquer should be added, 
 to bring the colour to a truer green, and less verging to the blue. 
 
 Other Colours . — The stones of more diluted colour, such as the 
 amethyst, topaz, vinegar-garnet, and eagle-marine, may be very 
 cheaply imitated by transparent white glass or paste, even without 
 foils. This is to be done, by tempering the colours above enume- 
 rated with turpentine and mastic, and painting the socket in which 
 the counterfeit stone is to be set with the mixture, the socket and 
 stone itself being previously heated. In this case, however, the stone 
 should be immediately set, and the socket closed upon it before the 
 mixture cools and grows hard. The orange-lake above-mentioned 
 was invented for this purpose, in which it has a beautiful effect, and 
 was used with great success by a considerable manufacturer. The 
 colour it produces is that of the vinegar-garnet, which it affords with 
 great brightness. The colours before directed to be used in oil should 
 be extremely well ground in oil of turpentine, and tempered with 
 old nut or poppy-oil or, if time can be given for their drying, with 
 strong fat oil 3 diluted with spirit of turpentine, which will gain a 
 fine polish of itself. 
 
 The colours used in varnish should be likewise thoroughly well 
 ground and mixt 3 and in the case of the dragon’s blood in the seed- 
 lac varnish and the lacquer, the foils should be warmed before they 
 are laid out. All the mixtures should be laid on the foils with a broad 
 soft brush, which must be passed from one end to the other, and.no 
 part should be crossed, or twice gone over, or, at least, not till the 
 
APPENDIX. 
 
 71B 
 
 first coat can be dry ; wlien, if the colour do not lie strong enough, 
 a second coat may be given. 
 
 GILDING, SILVERING, AND TINNING. 
 
 Gold powder for Gilding, — Gold powder may be prepared in 3 
 different ways : — 1st, put into an earthen, mortar some gold-leaf, 
 with a little honey, or thick gum-water, and grind the mixture till 
 the gold is reduced to extremely minute particles. When this is 
 done, a little warm water will wash out the honey or gum, leaving 
 the gold behind in a pulverulent state. 
 
 2nd.— Dissolve pure gold (or the leaf), in nitro-muriatic acid, 
 and tlien to precipitate it by a piece of copper, or by a solution of 
 sulphate of iron. The precipitate (if by copper,) must be digested 
 in distilled vinegar, and then washed, (by pouring water over it re- 
 peatedly,) and dried. This precipitate will be in the form of a very 
 fine powder : it works better, and is more easily burnished than gold 
 leaf ground with honey as above. 
 
 And 3d, or the best method of preparing gold powder, is by heating 
 a prepared amalgam of gold, in an open clean crucible, and conti- 
 nuing the strong heat until the whole of the mercury is evaporated j 
 at the same time constantly stirring the amalgam with a glass rod. 
 When the mercury has completely left the gold, the remaining pow- 
 der is to be ground in a Wedgewood’s mortar, with a little water, and 
 afterwards dried. It is then fit for use. 
 
 Although the last mode of operating has been here given, the ope- 
 rator cannot be too much reminded of the danger attending the sub- 
 limation of mercury. In the small way here described, it is impos- 
 sible to operate without danger ; it is therefore better to prepare it 
 according to the former directions, than to risk the health by the 
 latter. 
 
 To cover Bars of Copper ^ 8(c. with Gold, so as to he rolled out into 
 Sheets. — This method of gilding was invented by Mr. Turner, of 
 Birmingham. Mr. Turner first prepares ingots or pieces of copper 
 or brass, in convenient lengths and sizes. He then cleans them 
 from impurity, and makes their surfaces level, and prepares plates of 
 pure gold, or gold-mixed with a portion of alloy, of the same size as 
 the ingots of metal, and of suitable thickness. Having placed a 
 piece of gold upon an ingot intended to be plated, he hammers and 
 compresses them both together, so that they may have their surfaces 
 as nearly equal to each other as possible j and then binds them to- 
 gether with wire, in order to keep them in the same position during 
 the process required to attach them. Afterwards he takes silver 
 filings, which he mixes with borax, to assist the fusion of the silver. 
 This mixture he lays upon the edge of the plate of gold, and next to 
 the ingot of metal. Having thus prepared the two bodies, he places 
 them on a fire in a stove or furnace, \^ here they remain until the silver 
 
APPENDIX. 
 
 J19 
 
 and borax placed along the edges of the metals melt, and until the 
 adhesion of the gold with the metal is perfect. He then takes the 
 ingot carefully out of the stove. By this process the ingot is plated 
 with gold, and prepared ready for rolling into sheets. 
 
 To Gild in Colours. — The principal colours of gold for gilding are 
 red, green, and yellow. These should be kept in different amal- 
 gams. The part which is to remain of the first colour, is to be stop- 
 ped off with a composition of chalk and glue 3 the variety required 
 is produced by gilding the unstopped parts with the proper amalgam, 
 according to the usual mode of gilding. ^ 
 
 Sometimes the amalgam is applied to the surface to be gilt, with- 
 out any qnicking, by spreading it with aqua-fortis ; but this depends 
 on the same principle as a previous quicking. 
 
 Grecian Gilding. — Equal parts of sal-ammoniac and corrosive sub- 
 limate, are dissolved in spirit of nitre, and a solution of gold made 
 with this menstruum. The silver is brushed over with it, which is 
 turned black, but on exposure to a red heat it assumes the colour of 
 gold. 
 
 To dissolve Gold in Aqua-Regia. — Take an aqua-regia, composed 
 of two parts of nitrous acid, and one of marine acid 3 or of one 
 part of sal-ammoniac, and four parts of aqua-fortis 3 let the gold be 
 granulated, put into a sufficient quantity of this menstruum, and ex- 
 posed to a moderate degree of heat. During the solution, an effer- 
 vescence takes place, and it acquires a beautiful yellow colour, which 
 becomes more and more intense, till it has a golden or even orange 
 colour. When the menstruum is saturated, it is very clear and trans- 
 parent. 
 
 To gild Iron or Steel ivith a solution of Gold. — Make a solution of 
 Bounces of nitre and common salt, with 5 ounces of crude alum in a 
 sufficient quantity of water 3 dissolve half an ounce of gold thinly 
 plated and cut 3 and afterwards evaporate to dryness. Digest the 
 residuum in rectified spirit of wine or mther, which will perfectly ab- 
 stract the gold. The iron is brushed over with this solution and be- 
 comes immediately gilt. 
 
 To Gild, by dissolving Gold in Aqua-Regia. — Fine linen rags are 
 soaked in a saturated solution of gold in aqua-regia, gently dried, 
 and afterwards burnt to tinder. The substance to be gilt nrnst be well 
 polished 3 a piece of cork is first dipped into a solution of common 
 salt in water, and afterwards into the tinder, which is well rubbed on 
 the surface of the metal to be gilt, aud the gold appears in all its 
 metallic lustre. 
 
 Amalgam of Gold in the large way. — A quantity of quicksilver is 
 put into a crucible or iron ladle, which is lined with clay, and ex- 
 posed to heat till it begins to smoke. The gold to be mixed should 
 l)e previously granulated, and heated red hot, when it should be 
 added to the quicksilver, and stirred about with an iron rod till it is 
 perfectly dissolved. If there should be any superflous mercury, it 
 may be separated by passing it through clean soft leather j and the 
 
APPENDIX. 
 
 720 
 
 remaining amalgam will have the consistence of butter, and contain 
 about 3 parts of mercury to 1 of gold. 
 
 To Gild ly Amalgamation. — The metal to be gilt is previously 
 well cleaned on its surface, by boiling in a weak pickle, which is a 
 very dilute nitrous acid. A quantity of aqua-fortis is poured into an 
 earthen vessel, and quicksilver put therein 5 when a sufficient quan- 
 tity of mercury is dissolved, the articles to be gilt are put into the 
 solution, and stirred about with a brush till they become white. This 
 is called quicking. But, as during quicking by this mode, a noxious 
 vapour continually arises, which proves very injurious to the health 
 of the workmen, they have adopted another method, by which they, 
 in a great measure, avoid that danger. They now dissolve the quick- 
 silver in a bottle containing aqua-fortis, and leave it in the open air 
 during the solution, so that the noxious vapour escapes into the air. 
 Then a little of this solution is poured into a bason, and with a brush 
 dipped therein, they stroke over the surface of the metal to be gilt, 
 which immediately becomes quicked. The amalgam is now applied by 
 one of the following methods : — 
 
 1st. By proportioning it to the quantity of articles to be gilt, and 
 putting them into a white hat together, working them about with a 
 soft brush, till the amalgam is uniformly spread. 
 
 Or, 2dly. By applying a portion of the amalgam upon one part, 
 and spreading it on the surface, if flat, by working it about with a 
 harder brush. 
 
 The work thus managed is put into a pan, and exposed to a gentle 
 degree of heat 5 when it becomes hot, it is frequently put into a hat, 
 and worked about with a painter’s large brush, to prevent an irregular 
 dissipation of the mercury, till, at last, the quicksilver is entirely 
 dissipated by a repetition of the heat, and the gold is attached to the 
 surface of the metal. This gilt surface is well cleaned by a wire 
 brush, and then artists heighten the colour of the gold by the ap- 
 plication of various compositions ) this part of the process is called 
 
 COLOURIX’G. 
 
 To gild Glass and Porcelain. No. 1. — Drinking, and other glasses 
 are sometimes gilt on their edges. This is done, either by an adhe- 
 sive varnish or by heat. The varnish is prepared by dissolving in 
 boiled linseed oil an equal weight either of copal or amber. This is 
 to be diluted by a proper quantity of oil of turpentine, so as to be ap- 
 plied as thin as possible to the parts of the glass intended to be gilt. 
 When this is done, which will be in about twenty-four hours, the 
 glass is to be placed in a stove, till it is so warm as almost to burn 
 the fingers when handled. At this temperature, the varnish will 
 become adhesive, and a piece of leaf gold, applied in the usual way, 
 will immediately stick. Sweep off the superflous portions of the leaf, 
 and when quite cold, it may be burnished, taking care to interpose 
 a piece of very thin paper (India paper) betw'een the gold and the 
 burnisher. If the varnish is very good, this is the best method of 
 gilding glass, as the gold is thus fixed on more evenly than in any 
 other way. 
 
APPENDIX. 
 
 721 
 
 No. 2. — It often happens, when the varnish is but indifferent, that 
 by repeated washing the gold wears off j on this account the prac- 
 tice of burning it in is sometimes had recourse to. ^ 
 
 For this purpose, some gold powder is ground with borax, and in 
 this state applied to the clean surface of the glass, by a camel’s hair 
 pencil } when quite dry, the glass is put into a stove heated to about 
 the temperature of an annealing oven 5 the gum burns off, and the 
 borax, by vitrifying, cements the gold with great firmness to the 
 glass ; after which it may be burnished. The gilding upon porcelain 
 is in like manner fixed by heat and the use of borax •, and this kind 
 of ware being neither transparent nor liable to soften, and thus to be 
 injured in its form in a low red heat, is free from the risk and injury 
 which the finer and more fusible kinds of glass are apt to sustain 
 from such treatment. Porcelain and other wares may be platinised, 
 silvered, tinned, and bronzed, in a similar manner. 
 
 To Gild Leather. — In order to impress gilt figures, letters, and 
 other marks upon leather, as on the covers of books, edgings for 
 doors, &c. the leather must first be dusted over with very finely 
 powdered yellow resin, or mastich gum. The iron tools or stamps 
 are now arranged on a rack before a clear fire, so as to be well heated, 
 without becoming red hot. If the tools are letters j they have an al-, 
 phabetical arrangement on the rack. Each letter or stamp must be 
 tried as to its heat, by imprinting its mark on the raw side of a 
 piece of waste leather. A little practice will enable the workman to 
 judge of the heat. The tool is now to be pressed downwards on the 
 gold leaf } which will of course be indented, and shew the figure im- 
 printed on it. The next letter or stamp is now to be taken and 
 stamped in like manner and so on with the others 3 taking care to 
 keep the letters in an even line with each other, like those in a book. 
 By this operation the resin is melted ; consequently the gold ad- 
 heres to the leather : the superfluous gold may then be rubbed off by 
 a cloth 3 the gilded impressions remaining on the leather. In this, as 
 in every other operation, adroitness is acquired by practice. 
 
 The cloth alluded to should be slightly greasy, to retain the gold 
 wiped off 3 (otherwise there will be a great waste in a few months,) 
 the cloth will thus be soon completely saturated or loaded with the gold. 
 When this is the case, these cloths are generally sold to the refiners, 
 who burn them and recover the gold. Some of these afford so much gold 
 by burning, as to be worth from a guinea to a guinea and a half. 
 
 To Gild Writings, Drawings, &ic. on Paper or Parchment. — Let- 
 ters written on vellum or paper are gilded in three ways : in the first, 
 a little size is mixed with the ink, and the letters are written as 
 usual ; when they are dry, a slight degree of stickiness is produced 
 by breathing on them, upon which the gold leaf is immediately ap- 
 plied, and by a little pressure may be made to adhere with sufficient 
 firmness. In the second method, some white lead or chalk is ground 
 up with strong size, and the letters are made with this by means of 
 a brush : when the mixture is almost dry, the gold leaf may be laid 
 on, and afterwards burnished. The last method is to mix up some 
 
 3 A 
 
APPENDIX. 
 
 722 
 
 gold powder with size, and to form the letters of this by means of a 
 brush. It is supposed that this latter method was that used by the 
 monks in illuminating their missals, psalters, and rubrics. 
 
 To Gild the edges of Paper . — The edges of the leaves of books and 
 letter paper are gilded whilst in a horizontal position in the book- 
 binder’s press, by first applying a composition formed of four parts 
 of Armenian bole, and one of candied sugar, ground together with 
 water to a proper consistence, and laid on by a brush with the white 
 of an egg. This coating, when nearly dry, is smoothed by the bur- 
 nisher ; which is generally a crooked piece of agate, very smooth, 
 and fixed in a handle. It is then slightly moistened by a sponge dip- 
 ped in clean water, and squeezed in the hand. The gold leaf is now 
 taken up on a piece of cotton, from the leathern cushion, and applied 
 on the moistened surface. When dry, it is to be burnished by rubbing 
 the agate over it repeatedly from end to end, taking care not to wound 
 the surface by the point of the burnisher. A piece of silk or India 
 paper is usually interposed between the gold and the burnisher. 
 
 Cotton wool is generally used by bookbinders to take the leaf up 
 from the cushion ; being the best adapted for the purpose on ac- 
 count of its pliability, smoothness, softness, and slight moistness. 
 
 To gild Silk, Satiiiy Ivory, ^c. by Hydrogen Gas. No. 1.— -Im- 
 merse a piece of white satin, silk, or ivory in a solution of nitro-mn- 
 riate of gold, in the proportion of one part of the nitro-muriate to 
 three of distilled water. Whilst the substance to be gilded is still 
 wet, immerse it in a jar of hydrogen gas : it will soon be covered 
 by a complete coat of gold. 
 
 No, 2.— The foregoing experiment may be very prettily and ad- 
 vantageously varied as follows : — Paint flowers or other ornaments 
 with a very fine camel hair pencil, dipped in the above-mentioned 
 solution of gold, on pieces of silk, satin, &c. &c. &c. and hold them 
 over a Florence flask, from which hydrogen gas is evolved, during the 
 decomposition of the water by sulphuric acid and iron filings. The 
 painted flowers, &c. in a few minutes, will shine with all the splen- 
 dour of the purest gold. A coating of this kind will not tarnish on 
 exposure to the air, or in washing. 
 
 Oil gilding on Wood . — The wood must first be covered, or primed, 
 by two or three coatings of boiled linseed oil and carbonate of lead, 
 in order to fill up the pores, and conceal the irregularities of the sur- 
 face, occasioned by the veins in the wood. When the priming is 
 quite dry, a thin coat of gold-size must be laid on. This is prepared 
 by grinding together some red oxide of lead with the thickest drying 
 oil that can be procured, and the older the better, that it may work 
 freely : it is to be mixed, previously to being used, with a little oil of 
 turpentine, till it is brought to a proper consistence. If the gold- 
 size is good, it will be sufficiently dry in twelve hours, more or less, 
 to allow the artist to proceed to the last part of the process, which is 
 the application of the gold. For this purpose, a leaf of gold is spread 
 on a cushion (formed b^y a few folds of flannel secured on a piece of 
 wood, about eight inches square, by a tight covering of leather), and 
 
APPENDIX. 
 
 723 
 
 is cut into strips of a proper size by a blunt pallet knife j each strip 
 being then taken upon the point of a fine brush, is applied to the 
 part intended to be gilded, and is then gently pressed down by a ball 
 of soft cotton ; the gold immediately adheres to the sticky surface 
 of the size, and after a few minutes, the dexterous application of a 
 large camel’s hair brush sweeps away the loose particles of the gold 
 leaf without disturbing the rest. In a day or two the size will be 
 completely dried, and the operation will be finished. 
 
 The advantages of this method of gilding are, that it is very simple, 
 very durable, and not readily injured by changes of weather, even 
 when exposed to the open air ; and when soiled it may be cleaned by 
 a little warm water and a soft brush j its chief employment is in out- 
 door work. Its disadvantage is, that it cannot be burnished, and 
 therefore wants the high lustre produced by the following method. 
 
 To Gild by burnis king. -~~Th\s operation is chiefly performed on 
 picture frames, mouldings, headings, and fine stucco work. The 
 surface to be gilt must be carefully covered with a strong size, made 
 by boiling down pieces of white leather, or clippings of parchment, 
 till they are reduced to a stiff jelly ; this coating being dried, eight 
 or ten more must be applied, consisting of the same size, mixed with 
 fine Paris plaster or washed chalk j when a sufficient number of 
 layers have been put on, varying according to the nature of the work, 
 and the whole is become quite dry, a moderately thick layer must be 
 applied, composed of size and Armenian bole, or yellow oxide of lead : 
 while this last is yet moist, the gold leaf is to be put on in the usual 
 manner j it will immediately adhere on being pressed by the cotton 
 ball, and before the size is become perfectly dry, those parts which 
 are intended to be the most brilliant are to be carefully burnished by 
 an agate or dog’s tooth fixed in a handle. 
 
 In order to save the labour of burnishing, it is a common, but bad 
 practice, slightly to burnish the brilliant parts, and to deaden the 
 rest by drawing a brush over them dipped in size ; tlie required con- 
 trast between the polished and the unpolished gold is indeed thus 
 obtained ; but the general effect is much inferior to that produced in 
 the regular way, and the smallest drop of water falling on the sized 
 part occasions a stain. This kind of gildingcan only be applied on 
 in-door work 5 as rain, and even a considerable degree of dampness, 
 will occasion the gold to peel off. When dirty, it may be cleaned by 
 a soft brush, with hot spirit of wine, or oil of turpentine. 
 
 To Gild Copper^ S^c. by Amalgam. ^Immerse a very clean bright piece 
 of copper in a diluted solution of nitrate of mercury. By the affinity 
 of copper for nitric acid, the mercury will be precipitated ; now 
 spread the amalgam of gold rather thinly over the coat of mercury 
 just given to the copper. This coat unites with the amalgam, but of 
 course will remain on the copper. Now place the piece or pieces so 
 operated on, in a clean oven or furnace, where there is no smoke. If ^ 
 the heat is a little greater than 66'’, the mercury of the amalgam* 
 will be volatilised, and the copper will be beautifully gilt. 
 
 In the large way of gilding, the furnaces are so contrived that the 
 
 3 a2 
 
APPENDIX. 
 
 724 
 
 volatilised mercury is again condensed, and preserved for further use, 
 so that there is no loss in the operation. There is also a contrivance 
 by which the volatile particles of mercury are prevented from injuring 
 the gilders. 
 
 To Gild Steel. — Pour some of the ethereal solution of gold into a 
 wine glass, and dip therein the blade of a new pen-knife, lancet, or 
 razor ,• withdraw the instrument, and allow the ether to evaporate. 
 Ttie blade will be found to be covered by a very beautiful coat of 
 gold. A clean rag, or small piece of very dry sponge, may be dipped 
 in the ether, and used to moisten the blade, with the same result. 
 
 In this case there is no occasion to pour the liquid into a glass, 
 which must undoubtedly lose by evaporation ; but the rag or sponge 
 may be moistened by it, by applying either to the mouth of the phial. 
 This coating of gold will remain on the steel for a great length of 
 time, and will preserve it from rusting. 
 
 This is the way in which swords and other cutlery are ornamented. 
 Lancets too are in this way gilded with great advantage, to secure 
 them from rust. 
 
 To heighten the colour of Yellow Gold. 
 
 6 oz. saltpetre, 
 
 2 oz. copperas, 
 
 1 oz. white vitriol, and 
 1 oz. alum. 
 
 If it be wanted redder, a small portion of blue vitriol .ruist be 
 added. These are to be well-mixed, and dissolved in water as the 
 colour is wanted. 
 
 To heighten tne colour of Green Gold. 
 
 1 oz. 10 dwts. saltpetre, 
 
 1 oz. 4 dwts sal ammoniac, 
 
 1 oz. 4 dwts. Roman vitriol, and 
 18 dwts. verdigris. 
 
 Mix them, well together, aud dissolve a portion in water, as occa- 
 sion requires. 
 
 The work must be dipped in these compositions, applied to a proper 
 heat to burn them off, and then quenched in water or vinegar. 
 
 To heighten the colour of Red Gold. 
 
 To 4 oz. melted yellow wax, add 
 1^ oz. red ochre in fine pow'der, 
 
 1:^ oz. verdigris calcined till it yield no fumes, and 
 5 oz. calcined borax. 
 
 It is necessary to calcine the verdigris, or else, by the heat applied 
 in burning the wax, the vinegar becomes so concentrated as to cor- 
 rode the surfaces, and make it appear speckled. 
 
 To separate Gold from Gilt-Copper and iSzVuer.— Apply a solution 
 of borax, in water, to the gilt surface, with a fine brush, and sprinkle 
 over it some fine powdered sulphur. Make the piece red hot, and 
 quench it in water. The gold may be easily wiped off with a scratch- 
 brush, and recovered by testing it with lead. 
 
 Gold is taken from the surface of silver by spreading over it a 
 
APPENDIX. 
 
 725 
 
 paste, made of powdered sal ammoniac, with aqua fortis, and heating 
 it till the matter smokes, and is nearly dry j when the gold may be 
 separated by rubbing it with a scratch-brush. 
 
 To Silver hy Heat. No. 1. — Dissolve an ounce of pure sih^er in 
 aqua fortis, and precipitate it with common salt ; to which add Dh. 
 of sal ammoniac, sandiver, and white vitriol, and \ oz. of sublimate. 
 
 No. 2 — Dissolve an ounce of pure silver in aqua fortis ; preci- 
 pitate it with common salt, and add, after washing, 6 ounces of com- 
 mon salt, 3 ounces each of sandiver and white vitriol, and -l ounce 
 of sublimate. 
 
 These are to be ground into a paste upon a fine stone with a mul- 
 ler ; the substance to be silvered must be rubbed over with a suffi- 
 cient quantity of the paste, and exposed to a proper degree of heat. 
 Where the silver runs, it is taken from the fire, and dipped into weak 
 spirit of salt to clean it. 
 
 Silvering on Gilt Work, ly Amalgamation — Silver will not attach 
 itself to any metal by amalgamation, unless it be first gilt. The pro- 
 cess is the same as gilding in colours, only no acid should be used. 
 
 To Silver in the C(dd Way, 
 
 No. 1 .—2 dr. tartar, 
 
 2 dr. common salt, 
 dr. of alum, and 
 
 20 grs. of silver, precipitated from the nitrous 
 acid by copper. 
 
 Make them into a paste with a little water. This is to be rub- 
 bed on the surface to be silvered with a cork, &c. 
 
 No. 2. — Dissolve pure silver in aqua fortis, and precipitate the 
 silver with common salt ; make this precipitate into a paste, by 
 adding a little more salt and cream of tartar. It is applied as in the 
 former method. 
 
 To Silver Copper Ingots. — The principal difficulties in plating cop- 
 per ingots are, to bring the surfaces of the copper and silver into 
 fusion at the same time, and to prevent the copper from scaling j for 
 which purposes fluxes are used. The surface of the copper on which 
 the silver is to be fixed must be made flat by filing, and should be left 
 rough. The silver is first annealed, and afterwards pickled in weak 
 spirit of salt 5 it is planished, and then scraped on the surface to be 
 fitted on the copper. These prepared surfaces are annointed with 
 a solution of borax, or strewed with fine powdered borax itself, and 
 then confined in contact with each other, by binding wire. When 
 they are exposed to a sufficient degree of heat, the flux causes the 
 surffices to fuse at the same time, and after they become cold, they 
 are found firmly united. 
 
 Copper may likewise be plated by heating it, and burnishing leaf- 
 silver upon it 3 so may iron and brass. This process is called French 
 Plating. 
 
 To separate the Silver from Plated Copper.— This process is ap- 
 plied to recover the silver from the plated metal, which has been 
 rolled down for buttons, toys, &c. without destroying any large por- 
 
APPENDIX. 
 
 726 
 
 tion of the copper. For this purpose, a menstruum is composed of 
 3 pounds of oil of vitriol, ounce of nitre, and a pound of water. 
 The plated metal is boiled in it, till the silver is dissolved, and then 
 the silver is recovered by throwing common salt into the solution. 
 
 To Plate Iron. — Iron may be plated by three different modes. 
 
 1st. By polishing the surface very clean and level with a burnisher ; 
 and afterwards by exposing it to a blueing heat, a leaf of silver is 
 properly placed and carefully burnished down. This is repeated till 
 a sufficient number ©f leaves is applied, to give the silver a proper 
 body. 
 
 2d. By the use of a solder ; slips of thin solder are placed between 
 the iron and silver, with a little flux, and secured together by bind- 
 ing-wire. It is then placed in a clear fire, and continued in it till the 
 solder melts 5 when it is taken out, and on cooling is found to ad- 
 here firmly. 
 
 And 3d. By tinning the iron first, and uniting the silver by the in- 
 termedia of slips of rolled tin, brought into fusion in a gentle heat. 
 
 To tin Copper and Brass, — Boil six pounds of cream of tartar, four 
 gallons of water, and eight pounds of grain tin, or tin shavings. 
 After the materials have boiled a sufficient time, the substance to be 
 tinned is put therein, and the boiling continued, when the tin is pre- 
 cipitated in its metallic form. • 
 
 To tin Iron and Copper Vessels. — Iron which is to be tinned, must 
 be previously steeped in acid materials, such as sour whey, distillers’ 
 wash, &c. 5 then scoured and dipped in melted tin, having been first 
 rubbed over with a solution of sal ammoniac. The surface of the tin 
 is prevented from calcining, by covering it with a coat of fat. Cop- 
 per vessels must be well cleansed ; and then a sufficient quantity of 
 tin with sal ammoniac is put therein, and brought into fusion, and the 
 copper vessel moved about. A little resin is sometimes added. The 
 sal ammoniac prevents the copper from scaling, and causes the tin to 
 be fixed wherever it touches. Lately, zinc has been proposed for 
 lining vessels instead of tin, to avoid the ill consequences which have 
 been unjustly apprehended. 
 
 To prepare the Silver Tree.— Pour into a glass globe or decanter, 
 4 drachms of nitrate of silver, dissolved in a pound or more of dis- 
 tilled water, and lay the vessel on the chimney piece, or in some 
 place where it may not be disturbed. Now pour in 4 drachms of 
 mercury. In a short time the silver will be precipitated in the most 
 beautiful arborescent form, resembling real vegetation. This has been 
 generally termed the Arbor Dianae. 
 
 To prepare the Tin Tree. — Into the same or a similar vessel to that 
 used in the last experiment, pour distilled water as before, and put in 
 3 drachms of muriate of tin, adding 10 drops of nitric acid, and shake 
 the vessel until the salt be completely dissolved. Replace the zinc 
 (which must be cleared from the effects of the former experiment,) as 
 before, and set the whole aside to precipitate without disturbance. 
 In a few hours, the effect will be similar to the last, only that the tree 
 > of tin will have more lustre. In these experiments, it is surprising 
 
APPENDIX. 
 
 727 
 
 to observe the laminae shoot out as it were from nothing ; but this 
 phenomenon seems to proceed from a galvanic action of the metals 
 and the water. 
 
 To prepare the Lead Tree. — Put ^ an ounce of the super-acetate of 
 lead in powder, into a clear glass globe or wine decanter, filled to the 
 bottom of the neck with distilled water, and 1 0 drops of nitric acid, 
 and shake the mixture well. Prepare a rod of zinc with a hammer 
 and file, so that it may be a quarter of an inch thick and 1 inch long : at 
 the same time form notches in each side for a thread, by which it is to 
 be suspended,and tie the thread so that the knot shall be uppermost, 
 when the metal hangs quite perpendicular. When it is tied, pass the 
 two ends of the thread through a perforation in the cork, and let them 
 be again tied over a small splinter of wood which may pass between 
 them and the cork. When the string is tried, let the length between 
 the cork and the zinc be such that the precipitant (the zinc) may be 
 at equal distances from the side, bottom, and top, of the vessel, when 
 immersed in it. When all things are thus prepared, place the vessel 
 in a place where it may not be disturbed, and introduce the zinc, at 
 the same time fitting in the cork. The metal will very soon be co- 
 vered with the lead, which it precipitates from the solution, and this 
 will continue to take place until the whole be precipitated upon the 
 zinc, which will assume the form of a tree or bush, whose leaves and 
 branches are laminal, or plates of a metallic lustre. 
 
 Metallic Watering, or for Blanc Moire.— This article of Parisian 
 invention, which is much employed to cover ornamental cabinet work, 
 dressing-boxes, telescopes, opera glasses, &c, &c. is prepared in the 
 following manner. 
 
 Sulphuric acid is to be diluted with from seven to nine parts of water j 
 then dip a sponge or rag into it, and wash with it the surface of a 
 sheet of tin. This will speedily exhibit an appearance of crystal- 
 lization, which is the moir^. 
 
 This effect, however, cannot be easily produced upon every sort of 
 sheet tin, for if the sheet has been much hardened by hammering or 
 rolling, then the moir6 cannot be effected until the sheet has been 
 heated so as to produce an incipient fusion on the surface, after which 
 the acid will act upon it, and produce the raoir6. Almost any acid 
 will do as well as the sulphuric, and it is said, that the citric acid, 
 dissolved in a sufficient quantity of water, answers better than any 
 other. 
 
 The moir^ may be much improved by employing the blow-pipe, to 
 form small and beautiful specks on the surface of the tin, previous to 
 the application of the acid. 
 
 When the moir6 has been formed, the plate is to be varnished and 
 polished, the varnish being tinted with any glazing colour, and thus 
 the red, green, yellow, and pearl coloured moir6s are manuffictured. 
 
 Chinese Sheet Lead.-^The operation is carried on by two men j 
 one is seated on the floor with a large flat stone before him, and with 
 a moveable flat stone-stand at his side. His fellow workman stands 
 beside him with a crucible filled with melted lead j and having poured 
 
APPENDIX. 
 
 728 
 
 a certain quantity upon the stone, the other lifts the moveable stone, 
 and dashing it on the fluid lead, presses it out into a flat and thin 
 plate, which he instantly removes from the stone. A second quantity 
 of lead is poured in a similar manner, and a similar plate formed, the 
 process being carried on with singular rapidity. The rough edges of 
 the plates are then cut off, and they are soldered together for use. 
 
 Mr. Waddell has applied this method, with great success, to the 
 formation of thin plates of zinc, for galvanic purposes. 
 
 To plate Looking-Glasses . — This art is erroneously termed silver- 
 ing, for, as will be presently seen, there is not a particle of silver 
 present in the whole composition. 
 
 On tin-foil, fitly deposed on a flat table, mercury is to be poured, 
 and gently riihbed with a hare’s foot ; it soon unites itself with the 
 tin, which then becomes very splendid, or, as the workmen say, 
 is quickened. A plate of glass is then cautiously to be slid, upon the 
 tin-leaf, in such a manner as to sweep olf the redundant mercury, 
 which is not incorporated with the tin ; lead weights are then to be 
 placed on the glass, and, in a little time, the quicksilvered tin-foil 
 adheres so firmly to the glass, that the weights may be removed with- 
 out any danger of its falling off. The glass thus coated is a common 
 looking-glass. About two ounces of mercury are sufficient for cover- 
 ing three square feet of glass. 
 
 The success of this operation depends much on the cleanness of 
 the glass •, and the least dirt or dust on its surface, will pr?,vent the 
 adhesion of the amalgam or alloy. 
 
 Liquid Foil for silvering Glass Globes, 1. 
 
 1 oz clean lead, 
 
 1 oz. fine tin, \ 
 
 1 oz. bismuth, and 
 10 oz. quicksilver. 
 
 The lead and tin must be put into the ladle first, and so soon 'as 
 melted the bismuth must be added. Skim off the dross, remove the 
 ladle from the fire, and before it sets, add the quicksilver : stir the 
 whole carefully together, taking care not to breathe over it, as the 
 fumes of the mercury are very pernicious. Pour this through an 
 earthen pipe, into tlie glass globe, which turn repeatedly round. 
 
 No. 2.— 2 parts mercury, 
 
 1 part tin, 
 
 1 part lead, and 
 1 part bismuth. 
 
 No. 3.— 4 oz. quicksilver, and 
 tin-toil. 
 
 The quantity of tin-foil to be added, is so much as will become 
 barely fluid when mixed. Let the globe be clean and warm, and inject 
 the quicksilver by means of a pipe at the aperture, turning it about 
 till it is silvered all over. Let the remainder run out, and hang the 
 globe up. 
 
APPENDIX. 
 
 729 ) 
 
 LACQUERING. 
 
 Lacquer for Brass. 6 oz, seed lac, 
 
 2 oz. amber or copal, ground on poipbyry, 
 
 40 gr. of dragon’s blood, 
 
 30 gr. extract of red sandal wood, obtained by 
 water, 
 
 36 gr. of Oriental saffron, 
 
 4 oz. of pounded glass, and 
 40 oz. very pure alcohol. 
 
 To apply this varnish to articles or ornaments of brass, expose 
 them to a gentle heat, and dip them into varnish. Two or three 
 coatings may be applied in this manner, if necessary. The varnish is 
 durable, and has a beautiful colour. Articles varnished in this man- 
 ner, may be cleaned with water and a bit of dry rag. 
 
 Lacquer for Philosophical Instruments . — This lacquer or varnish is 
 destined to change, or to modify the colour of those bodies to which 
 it is applied. 
 
 J oz. of gum guttee, 
 
 2 oz. of gum sandaric, 
 
 2 oz. of gum elemi, 
 
 1 oz. of dragon’s blood, of the best quality, 
 
 1 oz. of seed lac, 
 
 f oz. of terra merita, 
 
 2 grains of Oriental saffron, 
 
 3 oz. of pounded glass, and 
 20 oz. of pure alcohol. 
 
 The tincture of saffron and of terra merita, is first obtained by infu- 
 sing them in alcohol for twenty-four hours, or exposing them to the 
 heat of the sun in summer. The tincture must be strained through 
 a piece of clean linen cloth, and ought to be strongly squeezed. This 
 tincture is poured over the dragon’s blood, the gum elemi, the seed 
 lac, and the gum guttae, all pounded and mixed with the glass. The 
 varnish is then made according to the directions before given. 
 
 It may be ajiplied with great advantage to philosophical instru- 
 ments : the use of it might be extended, also, to various cast or 
 moulded articles with which furniture is ornamented. 
 
 If the dragon’s blood be of the first quality, it may give too high a 
 colour ; in this case, the dose may be lessened at pleasure, as well as 
 that of the other colouring matters. 
 
 It is w’ith a similar kind of varnish that the artists of Geneva give 
 a golden orange colour to the small nails employed to ornament watch- 
 cases j but they keep the process very secret. A beautiful bright 
 colour might be easily communicated to this mixture j but they pre- 
 fer the orange colour, produced by certain compositions, the prepara- 
 tion of which has no relation to that of varnish, and which has been 
 successfully imitated with saline mixtures, in which orpiracnt is a 
 
APPENDIX. 
 
 730 
 
 principal ingredient. The nails are heated before they are immersed 
 in the varnish, and they are then spread out on sheets of dry paper. 
 
 Gold-coloured Lacquer, for brass Watch-cases, Watch-keys, 8ic . — 
 
 6 oz. of seed lac, 
 
 2 oz. of amber, 
 
 2 oz. of gum guttse, 
 
 24 gr. of extract of red sandal weed in water, 
 
 60 gr. of dragon’s blood, 
 
 36 gr. of Oriental saffron, 
 
 4 oz. of pounded glass, and 
 36 oz. of pure alcohol. 
 
 Grind the amber, the seed lac, gum guttae, and dragon’s blood on a 
 piece of porphyry 3 then mix them with the pounded glass, and add 
 the alcohol, after forming with it an infusion of the saffron and an 
 extract of the sandal wood. The varnish must then be completed as 
 before. The metal articles destined to be covered by this varnish, 
 are heated, and those which will admit of it, are immersed in packets. 
 The tint of the varnish may be varied, by modifying the doses of the 
 colouring substances. 
 
 Lacquer of a less drying quality » 
 
 4 oz. seed lac, 
 
 4 oz. sandarac, or mastic, 
 
 ^ oz. dragon’s blood, 
 
 36 gr. terra merita, 
 
 36 gr. gum guttae, V 
 
 5 oz. pounded glass, 
 
 2 oz. clear turpentine, 
 
 32 oz. essence of turpentine. 
 
 Extract, by infusion, the tincture of the colouring substances, and 
 then add the resinous bodies according to the directions for compound 
 mastic varnish. 
 
 Lacquer or varnishes of this kind are called changing, because, 
 when applied to metals, such as copper, brass, or hammered tin, or 
 to wooden boxes and other furniture, they communicate to them a 
 more agreeable colour. Besides, by their contact with the common 
 metals, they acquire a lustre which approaches that of the precious 
 metals, and to which, in consequence of peculiar intrinsic qualities or 
 certain laws of convention, a much- greater value is attached. It is 
 by means of these changing varnishes, that artists are able to com- 
 municate to their leaves of silver and copper, those shining colours 
 observed in foils. This product of industry becomes a source of 
 prosperity to the manufacturers of buttons and works formed with 
 foil, which, in the hands of the jeweller, contributes with so much 
 success to produce that reflection of the rays of light which doubles 
 the lustre and sparkling quality of precious stones. 
 
 It is to varnish of this kind that we are indebted for the manufac- 
 ture of gilt leather, which, taking refuge in England, has given place 
 to that of papier mach 6 , which is employed for the decoration of pa- 
 laces, theatres, &c. 
 
APPENDIX. 
 
 731 
 
 la the last place, it is by the effect of a foreign tint obtained 
 from the colouring part of saffron, that the scales of silver dissemi- 
 nated in confection d' hyacinthe reflect a beautiful gold colour. 
 
 The colours transmitted by different colouring substances, require 
 tones suited to the objects for which they are destined. The artist 
 has it in his own power to vary them at pleasure. The addition of 
 annatto to the mixture of dragon’s blood, saffron, &c. or some changes 
 in the doses of the mode intended to be made in colours. It is, 
 therefore, impossible to give limited formulae. 
 
 To make Lacquer of various Tints, 
 
 Infuse separately 
 
 4 oz. gum guttae in 
 32 oz. of essence of turpentine, 
 
 1 oz. annatto, and 
 
 4 oz. dragon’s blood, also in separate doses of es- 
 sence. 
 
 These infusions may be easily made in the sun. After fifteen 
 days’ exposure, pour a certain quantity of these liquors into a flask, 
 and by varying the doses different shades of colour will be obtained. 
 
 These infusions may be employed also for changing alcoholic var- 
 nishes ; but in this case, the use of saffron, as well as that of red 
 sandal wood, which does not succeed with essence, will soon give the 
 tone necessary for imitating, with other tinctures, the colour of gold. 
 
 To Bronze Plaster Figures. — For the ground, after it has been 
 sized and rubbed down, take Prussian blue, verditer, and spruce 
 ochre. Grind them separately in water, turpentine, or oil, according 
 to the work, and mix them in such proportions as will produce the 
 colour desired. Then grind Dutch metal in a part of this composi- 
 tion : laying it with judgment on the prominent parts of the figure, 
 which produces a grand effect. 
 
 To Brown Gun Barrels. — After the barrel is finished rub it over 
 with aquafortis, or spirit of salt, diluted with water. Then lay it 
 by for a week, till a complete coat of oil is formed. A little oil is 
 then to be applied, and after rubbing the surface dry, polish it with 
 a hard brush and a little bees’ wax. 
 
 VARNISHES. 
 
 To makeWhite Copal Varnish, — No. 1.— White oxide of lead, ceruse, 
 Spanish white, white clay. Such of these substances as are preferred 
 ought to be carefully dried. Ceruse and clays obstinately retain a 
 great deal of humidity, which would oppose their adhesion to drying 
 oil or varnish. The cement then crumbles under the fingers, and 
 does not assume a body. 
 
 No. 2. — On 16 ounces of melted copal, pour 4, 6, or 8 ounces of 
 linseed oil, boiled and quite free from grease. When well mixed by 
 repeated stirrings, and after they are pretty cool, pour in 1 6 ounces 
 
APPENDIX 
 
 732 
 
 of the essence of Venice turpentine. Pass the varnish through a 
 cloth. Amber varnish is made the same way. 
 
 Black. — Lamp-black, made of burnt vine twigs, and blacK of peach- 
 stones. The lamp-black must be carefully washed, and afterwards 
 dried. Washing carries off a great many of its impurities. 
 
 Yclloiv. — Yellow oxide of lead of Naples and Montj)eilier, both re- 
 duced to impalpable powder. These yellows are hurt by the contact 
 of iron and steel ; in mixing them up, therefore, a horn spatula 
 with a glass mortar and pestle must be employed. 
 
 Gum guttae, yellow ochre, or Dutch pink, according to the nature 
 and tone of the colour to be imitated. 
 
 ^/mc. — I ndigo, prussiate of iron, (Prussian blue) blue verditer, 
 and ultra-marine. All these substances must be very much divided. 
 
 Green. — Verdigris, crystallized verdigris, compound green, (a mix- 
 ture of yellow and blue.) The first two require a mixture of white 
 in proper proportions, from a fourth to two-thirds, according to the 
 tint intended to be given. The v/hite used for this purpose is ceruse, 
 or the white oxide of lead, or Spanish white, which is less solid, or 
 w hite of Moudon. 
 
 ' Red. — Red sulphurated oxide of mercury, (cinnabar vermilion.) 
 Red oxide of lead (minium,) different red ochres, or Prussian 
 reds, &c. 
 
 Purple. — Cochineal, carmine, and carminated lakes, with ceruse * 
 and boiled oil. 
 
 Brick Red, — Dragon’s blood. 
 
 Chamois Colour. — Dragon’s blood with a paste composed of 
 flowers of zinc, or, what is still better, a little red vermilion. 
 
 Violet. — Red sulphurated oxide of mercury, mixed with lamp-black, 
 washed very dry, or with the black of burnt vine-twigs ; and to ren- 
 der it mellowmr, a proper mixture of red, blue^ and white. 
 
 Pearl Grey. — White and black 5 white and blue 3 for example, 
 ceruse and lamp-black j ceruse and indigo. 
 
 Flaxen Grey. — ^Ceruse, which forms the ground of the paste, 
 mixed with a small quantity of Cologne earth, as much English red, 
 or carminated lake, which is not so durable, and a particle of 
 prussiate of iron, (Prussian blue.) 
 
 To make Famishes for Violins , To a gallon of rectified spi- 
 
 rit of wdne, add six ounces of gum sandarac, three ounces of gum 
 mastich, and half a pint of turpentine varnish. Put tlje whole into 
 a tin can, which keep in a warm place, frequently shaking it, for 
 twelve days, until it is dissolved. Then strain, and keep it for use. 
 
 To dissolve Elastic Gmuy &;c. — M. Grossart, by an ingenious me- 
 thod, succeeded in forming India rubber into elastic tubes. Cut a 
 bottle of the gum circularly, in a spiral slip, of a few lines in breadth ; 
 then plunge the whole of the slip into vitriolic ether, till it becomes 
 softened 3 half an hour is generally sufficient for this purpose. The 
 slip is then taken out of the liquid, and one of the extremities a])plied 
 to the end of a mould, first rolling it on itself, and pressing it, then 
 mounting spirally along the cylinder, taking care to lay over and 
 
APPENDIX. 
 
 733 
 
 compress with the hand every edge, one against the other, so that 
 there may not be any vacant space, and that all the edges may join 
 exactly 3 the whole is then to be bound hard with a tape of an inoh 
 in width, taking care to turn it the same way with the slip of 
 caoutchouc. Over the tape packthread is to be applied, in 
 such a manner that, by every turn of the thread joining another, an 
 equal pressure is given to every part. It is then left to dry, and the 
 tube is made. In removing the bandage, great care must be taken 
 that none of the outward surface, which may have lodged within the 
 interstices of the tape, (of which the caoutchouc takes the exact im- 
 pression,) may be pulled asunder. If it be found difficult to withdraw 
 the mould, it may be plunged into hot water. If the mould were pre- 
 viously smoked or rubbed with chalk, it might be removed with less 
 difficulty. Polished metallic cylinders are the most eligible moulds 
 for this purpose. As solvents, oils of turpentine and lavender may 
 be employed, but both are much slower of evaporating than ether, and 
 tiie oil of turpentine, particularly, appears always to have a kind of 
 stickiness. Nevertheless, there is a solvent which has not that 
 inconvenience, is cheaper, and may easily be procured by every one, 
 viz. water. Proceed in the same manner as with ether. The 
 caoutchouc is sufficiently prepared for use when it has been a quarter 
 of an hour in boiling water : by this time its edges are sometimes 
 transparent. It is to be turned spirally round the mould, and re- 
 plunged frequently into the boiling water, during the time employed 
 in forming the tube. When the w'hole is bound with pack-thread, it 
 is to be kept some hours in boiling water, after which it is to be dried, 
 still keeping on the binding. This method may be successfully em- 
 ployed in forming the larger sort of tubes, and in any other instru- 
 ments, but it would be impracticable to make the small tubes in this 
 way. 
 
 Oil of lavender, of turpentine, and of spikenard, dissolve elastic 
 guih, with the assistance of a gentle heat 3 but a mixture of volatile 
 oil and alcohol forms a better solvent for it than oil alone, and the 
 varnish dries sooner. If boiled in a solution of alum in water, it is 
 rendered softer than in water alone. Yellow wax, in a state of ebul- 
 lition, may be saturated with it, by putting it, cut in small pieces, 
 gradually into it. By this means, a pliable varnish is formed, which 
 may be applied to cloth with a brush, but it still retains a clamminess. 
 
 To make Caoutchouc Famish. 
 
 16 oz. of caoutchouc, or elastic resin, 
 
 16 oz. boiled linseed oil, and 
 16 oz. of essence of turpentine. 
 
 Cut the caoutchouc into thin slips, and put them into a matrass 
 placed in a very hot sand-bath. When the matter is liquefied, add 
 the linseed oil in a state of ebullition, and then the essence warm. 
 AVhen the varnish has lost a great part of its heat, strain it through 
 a piece of linen, and preserve it in a wide-mouthed bottle. This 
 varnish <jries very slowly, a fault which is owing to the peculiar na- 
 ture of the caoutchouc. 
 
APPENDIX. 
 
 734 
 
 The invention of air balloons led to the idea of applying caout- 
 chouc to the composition of varnish. It was necessary to have a 
 varnish which should unite great pliability and consistence. No var- 
 nish seemed capable of corresponding to these views, except that of 
 caoutchouc, but the desiccation of it is exceedingly tedious. 
 
 To make Varnish for Silks, S;c. — To one quart of cold-drawn lin- 
 seed oil, poured off from the lees, (produced on the addition of un- 
 slacked lime, on which the oil has stood eight or ten days at the 
 least, in order to communicate a drying quality, — or brown umber, 
 burnt and powdered, which will have the like effect,) and half an 
 ounce of litharge 3 boil them for half an hour, then add half an ounce 
 of the copal varnish. While the ingredients are on the fire, in a 
 copper vessel, put in one ounce of chios turpentine, or common, 
 resin, and a few drops of neatsfoot oil, and stir the whole with a 
 knife 3 when cool, it is ready for use. The neatsfoot oil prevents 
 the varnish from being sticky or adhesive, and may be put into the 
 linseed oil at the same time with the lime, or burnt umber. Resin 
 or Chios turpentine may be added, till the varnish has attained the 
 desired thickness. 
 
 The longer the raw linseed oil remains on the un slacked lime or 
 umber, the sooner will the oil dry after it is used 3 if some months, 
 so much the better : such varnish will set, that is to say, not run, but 
 keep its place on the silk in four hours 3 the silk may then be turned, 
 and varnished on the other side. 
 
 To make pliable Varnish for Umbrellas, — Take any quantity of 
 caoutchouc, as ten or twelve ounces, cut into small bits with a pair of 
 scissors, and put a strong iron ladle, (such as that in which painters, 
 plumbers, or glaziers melt their lead) over a common pit-coal or other 
 fire 3 which must be gentle, glowing, and without smoke. When the la- 
 dle is hot, put a single bit into it : if black smoke issues, it will pre- 
 sently flame and disappear, or it will evaporate without flame 3 the 
 ladle is then too hot. When the ladle is less hot, put in a second bit, 
 which will produce a white smoke 5 this white smoke will continue 
 during the operation, and evaporate the caoutchouc 3 therefore no 
 time is to be lost, but little bits are to be put in, a few at a time, till 
 the whole are melted 3 it should be continually and gently stirred with 
 an iron or brass spoon. The instant the smoke changes from w'hite 
 to black, take off the ladle, or the whole will break out into a violent 
 flame, or be spoiled, or lost. Care must be taken that no wmter be 
 added, a few drops only of which would, on account of its expansi- 
 bility, make it boil over furiously and with great noise j at this period 
 of the process, 2 pounds or 1 quart of the best drying oil is to be put 
 into the melted caoutchouc, and stirred till hot, and the whole poured 
 into a glazed vessel through a coarse gauze, or wire sieve. When 
 settled and clear, which will be in a few minutes, it is fit for use, 
 either hot or cold. 
 
 The silk should be always stretched horizontally by pins or tenter- 
 hooks on frames : (the greater they are in length the better,) and the 
 varnish poured on cold in hot weather, and hot in cold weather. It 
 
APPENDIX. 
 
 735 
 
 is perhaps best, always to lay it on when cdid. The art of laying it 
 on properly, consists in making no intestine motion in the varnish, 
 which would create minute bubbles, therefore brushes of every kind 
 are improper, as each bubble breaks in drying, and forms a small hole, 
 through which the air will transpire. 
 
 This varnish is pliant, unadhesive, and unalterable by vA^eather. 
 
 Varnish used for Indian Shields, — Shields made at Silhet, in Ben- 
 gal, are noted throughout India, for the lustre and durahility of the 
 black varnish with which they are covered 3 Silhet shields constitute, 
 therefore, no inconsiderable article of traffic, being in request among 
 natives who carry arms, and retain the ancient predilection for the 
 scimitar and buckler. The varnish is composed of the expressed 
 juice of the marking nut, Semecarpus Anacardium, and that of 
 another kindred fruit, Holigarna Longifolia. 
 
 The shell of the Semecarpus Anacardium contains between its 
 integuments numerous cells, filled with a black, acrid, resinous juice 3 
 which likewise is found, though less abundantly, in the wood of the 
 tree. It is commonly employed as an indelible ink, to mark all sorts 
 of cotton cloth. The colour is fixed with quick lime. The cortical 
 part of the fruit of Holigarna Longifolia likewise contains between 
 its lamincB numerous cells, filled with a black, thick, acrid fluid. 
 The natives of Malabar, extract by incision, with which they varnish 
 targets. 
 
 To prepare the varnish according to the method practised in Silhet, 
 the nuts of the Semecarpus Anacardium^ and the berries of the 
 Holigarna Longifolia, having been steeped for a month in clear water, 
 are cut transversely, and pressed in a mill. The expressed juice of 
 each is kept for several months, taking off the scum from time to 
 time. Afterwards the liquor is decanted, and two parts of the one 
 are added to one part of the other, to be used as varnish. Other 
 proportions of ingredients are sometimes employed : but in all the 
 resinous juice of the Setnocarpus predominates. The varnish is laid 
 on like paint, and when dry, is polished by rubbing it with an agate, 
 or smooth pebble. This varnish also prevents destruction of wood, 
 &c. by the white ant. 
 
 To give a drying quality to Poppy Oil, 
 
 31b. of pure water, 
 
 1 oz. of sulphate of zinc, (white vitriol), and 
 
 2 lb. of oil of pinks, or poppy oil. 
 
 Expose this mixture in an earthen vessel capable of standing the 
 fire, to a degree of heat sufficient to maintain it in a slight state of 
 ebullition. When one half or two-thirds of the water has evaporated, 
 pour the whole into a large glass bottle or jar, and leave it at rest 
 till the oil becomes clear. Decant the clearest part by means of a 
 glass funnel, the beak of which is stopped with a piece of cork ; 
 when the separation of the oil from the water is completely effected, 
 remove the cork stopper, and supply its place by the fore-finger, 
 which must be applied in such a manner as to suffer the water to es- 
 cape, and to retain only the oil. 
 
APPENDIX. 
 
 736 
 
 Poppyoil when prepared in this manner becomes, after some 
 weeks, exceedingly limpid and colourless. 
 
 To give a drying quality to fat Oils, 
 
 No. 1. — 81b. nut-oil, or linseed-oil, 
 
 1 oz. white lead, slightly calcined, 
 
 1 oz. yellow acetate of lead, (sal. saturni) also calcined, 
 
 I oz. sulphate of zinc, (white vitriol,) 
 
 12 oz. vitreous oxide of lead, (litharge) and 
 a head of garlic, or a small onion. 
 
 When the dry substances are pulverized, mix them with the garlic 
 and oil, over a fire capable of maintaining the oil in a slight state of 
 ebullition : continue it till the oil ceases to throw up scum, till it 
 assumes a reddish colour, and till the head of garlic becomes brown. 
 A pellicle will then be soon formed on the oil, which indicates that 
 the operation is completed. Take the vessel from the fire, and the 
 pellicle, being precipitated by rest, will carry with it all the unctuous 
 parts which rendered the oil fat. When the oil becomes clear, sepa- 
 rate it from the deposit, and put it into wide-mouthed bottles, where 
 it will completely clarify itself in time, and improve in quality. 
 
 No. 2. — oz. of vitreous oxide of lead, (litharge) 
 
 I oz. sulphate of zinc, (white vitriol) and 
 16 oz. linseed, or nut-oil. 
 
 The operation must be conducted as in the preceding case. 
 
 The choice of the oil is not a matter of indifference. If it be des- 
 tined for painting articles exposed to the impression of the external 
 air, or for delicate painting, nut-oil or poppy-oil will be requisite. 
 Linseed oil is used for coarse painting, and that sheltered from the 
 effects of the rain and of the sun. 
 
 A little negligence in the management of the fire, has often' an in- 
 fluence on the colour of the oil, to which a drying quality is com- 
 municated j in this case it is not proper for delicate painting This 
 inconvenience may be avoided by tyiigup the drying matters in a 
 small bag j but the dose of the litharge must then be doubled. The 
 bag must be suspended by a piece of packthread fastened to a stick, 
 which is made to rest on the edge of the v ssel in such a manner 
 as to keep the bag at the distance of an inch from the bottom of the 
 vessel. A pellicle wiW be formed as in the first operation, but it will 
 be slower in making its appearance. 
 
 No 3. — A drying quality may be communicated to oil by treating, 
 in a heat capabKb of maintaining a slight ebullition, linseed, or nut oil, 
 to each pound of which is added 3 oz. of vitreous oxide of lead, 
 (litharge) reduced to fine pow'der. 
 
 The preparation of floor-cloths, and all paintings of large figures 
 or ornaments, in which argillaceous colours, such as yellow and red 
 boles, Dutch pink, &c. are employed, require this kind of preparation, 
 that the desiccation may not be too slow but painting for which 
 metallic oxides are used, such as preparations of lead, copper, &c. 
 require only the doses before indicated, because these oxides contain 
 
APPENDIX. 737 
 
 a great deal of oxygen, and the oil, by their contact, aequires more 
 of a drying quality. 
 
 No. 4.-2 lbs. of nut-oil, 
 
 3 lbs. of common water, and 
 
 2 oz. of sulphate of zinc, (white vitriol). 
 
 Mix these matters, and subject them to a slight ebullition, till 
 little water remains. Decant the oil, which will pass over with a 
 small quantity of water, and separate the latter by means of a funnel. 
 The oil remains nebulous for some time 3 after which it becomes 
 clear, and seems to be very little coloured. 
 
 No. 5.-6 lbs. of nut-oil, or linseed-oil, 
 
 4 lbs. of common water, 
 
 1 oz. of sulphate of zinc, and 
 
 1 head of garlic. 
 
 Mix these matters in a large iron or copper pan 3 then place 
 them over the fire, and maintain the mixture in a state of ebullition 
 during the whole day : boiling water must from time to time be added 
 to make up for the loss of that by evaporation. The garlic will as- 
 sume a brown appearance. Take the pan from the fire, and having 
 suffered a deposit to be formed, decant the oil, which will clarify it- 
 self in the vessels. By this process the drying oil is rendered some- 
 what more coloured : it is reserved for delicate colours. 
 
 Resinous Drying Of/.— Take 10 lbs. of drying nut oil, if the paint 
 is destined for external, or 10 lbs. of drying linseed oil, if for internal 
 articles. 
 
 3 lbs. of resin, and 
 6 oz. of turpentine. 
 
 Cause the resin to dissolve the oil by means of a gentle heat. 
 When dissolved and incorporated wdth the oil, add the turpentine ; 
 leave the varnish at rest, by which means it will often deposit por- 
 tions of resin and other impurities ; and then preserve it in wide- 
 mouthed bottles. It must be used fresh ; when suffered to grow old 
 it abandons some of its resin. If this resinous oil assumes too much 
 consistence, dilute it with a little essence, if intended for articles 
 sheltered from the sun, or with oil of poppies. 
 
 In Switzerland, where the principal part of the mason’s work con- 
 sists of stones subject to crumble to pieces, it is often found neces- 
 sary to give them a coating of oil paint, to stop the effects of this 
 decomposition. This painting has a great deal of lustre, and when 
 the last coating is applied with resinous oil, it has the effect of a var- 
 nish. To give it more durability, the first ought to be applied ex- 
 ceedingly warm and with plain oil, or oil very little charged, with the 
 grey colour, which is added to the two following.— 
 
 Fat Copal Varnish. 
 
 16 02 . of picked copal, 
 
 8 oz. of prepared linseed oil, or oil of poppies, and 
 16 oz. of essence of turpentine. 
 
 Liquefy the copal in a matrass over a common fire, and then add 
 the linseed oil, or oil of poppies, in a state of ebullition ; when these 
 
 3 B 
 
APPENDIX. 
 
 738 
 
 matters are incorporated, take the matrass from the fire, stir the mat- 
 ter till the greatest heat is subsided, and then add the essence of 
 turpentine warm. Strain the whole, while still warm, through a 
 piece of linen, and put the varnish into a wide-mouthed bottle. Time 
 contributes towards its clarification 5 and in this manner it acquires 
 a better quality. 
 
 Varnish for IVatcJi-Cases, in imitation of Tortoise-shell. 
 
 6 oz. of copal of an amber colour, 
 oz. Venice turpentine, 
 
 24 oz. prepared linseed oil, and 
 6 oz. essence of turpentine. 
 
 It is customary to place the turpentine over the copal, reduced to 
 small fragments, in the bottom of an earthen or metal vessil, or in a 
 matrass exposed to such a heat as to liquefy the copal : but it is more 
 advantageous to liquefy the latter alone, to add the oil in a state of 
 ebullition, then the turpentine liquefied, and in the last place, the 
 essence. If the varnish is too thick, some essence may be added. 
 The latter liquor is a regulator for the consistence in the hands of an 
 artist. 
 
 To make a Colourless Copal Varnish. — As all copal is not fit for this 
 purpose, in order to ascertain such pieces as are good, each must be 
 taken separately, and a single drop of pure essential oil of rosemary, 
 not altered by keeping, must be let fall on it. Those pieces which 
 soften at the part that imbibes the oil, are good j reduce them to 
 powder, which sift through a very fine hair-sieve, and put it into a 
 glass, on the bottom of which it must not lie more than a finger’s 
 breadth thick. Pour upon it essence of rosemary to a similar height 5 
 stir the whole for a few minutes, when the copal will dissolve into a 
 viscous fluid. Let it stand for two hours, and then pour gently on 
 it two or three drops of very pure alcohol, which distribute over the 
 oily mass, by inclining the bottle in different directions with a very 
 gentle motion. Repeat this operation by little and little, till the in- 
 corporation is effected, and the varnish reduced to a proper degree of 
 fluidity. It must then be left to stand a few days, and, when very 
 clear, be decanted off. This varnish, thus made without heat, may 
 be applied with equal success, to pasteboard, wood, and metals, and 
 takes a better polish than any other. It may be used on paintings, 
 the beauty of which it greatly heightens. 
 
 Gold*coloured Copal Varnish. 
 
 1 oz. Copal in powder, 
 
 2 oz. essential oil of lavender, and 
 
 6 oz. essence of turpentine. 
 
 Put the essential oil of lavender into a matrass of a proper size, 
 placed on a sand-bath heated by an Argand’s lamp, or over a mo- 
 derate coal-fire. Add to the oil while very warm, and at several 
 times, the copal powder, and stir the mixture with a stick of white 
 wood, rounded at the end. When the copal has entirely disappeared, 
 add at three different times the essence almost in a state of ebullition, 
 and keep continually stirring the mixture. When the solution is 
 
APPENDIX, 73^ 
 
 completed, the result will be a varnish of a gold colour, exceeding- 
 ly durable and brilliant, but less drying than the preceding. 
 
 No. 2. To obtain this varnish colourless, it will be proper to recti- 
 fy the essence of the shops, which is often highly coloured, and ta 
 give it the necessary density by exposure to the sun in bottles closed 
 with cork stoppers, leaving an interval of some inches between the 
 stopper and the surface of the liquid. A few months are thus suffi- 
 cient to communicate to it the required qualities. Besides, the es- 
 sence of the shops is rarely possessed of that state of consistence, 
 without having at the same time a strong amber colour. 
 
 The varnish resulting from the solution of copal in oil of turpentine, 
 brought to such a state as to produce the maximum of solution, is ex- 
 ceedingly durable and brilliant. It resists the shock of hard bodies 
 much better than the enamel of toys, which often becomes scratched 
 and whitened by the impression of repeated friction ; it is applied 
 with the greatest success to philosophical instruments, and the paint- 
 ings with which vessels and other utensils of metal are decorated. 
 
 No. 3. — 4 oz. copal, and 
 
 1 oz. clear turpentine. 
 
 Put the copal, coarsely pulverized, into a varnish pot, and give it 
 the form of a pyramid, which must be covered w'ith turpentine. Shut 
 the vessel closely, and placing it over a gentle fire, increase the heat 
 gradually that it may not attack the copal ; as soon as the matter is 
 well liquefied, pour it upon a plate of copper, and when it has re- 
 sumed its consistence reduce it to powder. 
 
 Put half an ounce of this powder into a matrass w ith four ounces of 
 the essence of turpentine, and stir the mixture till the solid matter is 
 entirely dissolved. 
 
 Camphorated Copal Varnish . — This varnish is destined for articles 
 which require durability, pliableness, and transparency, such as the 
 varnished wire-gauze, used in ships instead of glass. 
 
 2 oz. of pulverized copal, 
 
 6 oz. of essential oil of lavender, 
 
 IT of an oz. of camphor, and 
 essence of turpentine, a sufficient quantity, ac- 
 cording to the consistence required to be given 
 to the varnish. 
 
 Put into a phial of thin glass, or into a small matrass, the essen- 
 tial oil of lavender and the camphor, and place the mixture on a 
 moderately open fire, to bring the oil and the camphor to a slight state 
 of ebullition j then add the copal pow der in small portions, which 
 must be renewed as they disappear in the liquid. Favour the solu- 
 tion, by continually stirring it with a stick of white wood ; and when 
 the copal is incorporated with the oil, add the essence of turpentine 
 boiling : but care must be taken to pour in, at first, only a small 
 portion. 
 
 This varnish is little coloured, and by rest it acquires a transpa- 
 rency which, united to the solidity observed in almost every kind of 
 copal varnishes, renders it fit to be applied with [great success in 
 
 3 B 2 
 
APPENDIX. 
 
 740 
 
 many casCvS, and particularly in the ingenious invention of substi- 
 tuting varnished metallic gauze in the room of Muscovy talc, a kind 
 of mica, in large laminae, used for the cabin windows of ships, as 
 presenting more resistance to the concussion of the air during the 
 firing of the guns. Varnished metallic gauze, of this kind, is ma- 
 nufactured at Rouen. 
 
 Ethereal Copal Varnish. — \ oz. of amberry copal, and 
 2 oz. of ether. 
 
 Reduce the copal to a very fine, powder, and introduce it by small 
 portions into the flask which contains the ether 3 close the flask with 
 a glass or cork stopper, and having shaken the mixture for half an 
 hour, leave it at rest till the next morning. In shaking the flask, if 
 the sides become covered with small undulations . and if the liquor be 
 not exceedingly clear, the solution is not complete. In this case, add 
 a little ether, and leave the mixture at rest. *^he varnish is of a 
 light lemon colour. The largest quantity of copal united to ether 
 may be a fourth, and the least a fifth. The use of copal varnish made 
 with ether seems, by the expense attending it, to be confined to re- 
 pairing those accidents which frequently happen to the enamel of 
 toys, as it will supply the place of glass to the coloured varnishes 
 employed for mending fractures, or to restoring the smooth surface 
 of paintings which have been cracked and shattered. 
 
 The great volatility of ether, and in particular its high price, do 
 not allow the application of this varnish to be recommended, but for 
 the purpose here indicated. It has been applied to wood with com- 
 plete success, and the glazing it produced, united lustre to solidity. 
 In consequence of the too speedy evaporation of the liquid, it often 
 boils under the brush. Its evaporation, however, may be retarded, 
 by spreading over the wood a slight stratum of essential oil of rose- 
 mary, or lavender, or even of turpentine, which may afterwards be 
 removed by a piece of linen rag 5 what remains is sufficient to retard 
 the evaporation of the ether. 
 
 Turpentine Copal Varnish. 
 
 H oz. of copal, of an amber colour, and in powder, and 
 8 oz. of best oil of turpentine. 
 
 Expose the essence to a balneum marice, in a wide-mouthed matrass 
 with a short neck 3 as soon as the water of the bath begins to boil, 
 throw into the essence a large pinch of copal powder, and keep the 
 matrass in a state of circular motion. When the powder is incor- 
 porated with the essence, add new doses of it 5 and continue in this 
 nmnner till you observe that there is formed an insoluble deposit. 
 Then take the matrass from the bath, and leave it at rest for some 
 days. Draw off the clear varnish, and filter it through cotton. 
 
 At the moment when the first portion of the copal is thrown into 
 the essence, if the powder precipitate itself under the form of lumps, 
 it is needless to proceed any further. This effect arises from two 
 causes : either the essence does not possess the proper degree of 
 concentration, or it has not been sufficiently deprived of water. 
 Exposure to the sun, employing the same matrass, to which a cork 
 
APPENDIX. 
 
 741 
 
 Stopper ought to be added, will give it the qualities requisite for the 
 solution of the copal. This effect will be announced by the disap- 
 pearance of the portion of copal already put into it. 
 
 Another Copal Varnish. 
 
 3 oz. of copal, liquefied, and 
 20 oz. of essence of turpentine. 
 
 Place the matrass containing the oil in a balneum mariae, and when 
 the water boils add the pulverized copal in small doses. Keep stir- 
 ring the mixture, and add no more copal till the former be incorpo- 
 rated with the oil. If the oil, in consequence of its particular dispo- 
 sition, can take up 3 ounces of it, add a little more ; but stop, if the 
 liquid becomes nebulous, then leave the varnish at rest. If it be too 
 thick, dilute it with a little warm essence, after having heated it in 
 the balneum mariae. When cold, filter it through cotton, and pre- 
 serve it in a clean bottle. 
 
 This varnish has a good consistence, and is as free from colour as 
 the best alcoholic varnish. When extended in one stratum over 
 smooth wood, which has undergone no preparation, it forms a very 
 brilliant glazing, which, in the course of two days, in summer, ac- 
 quires all the solidity that may be required. 
 
 The facility which attends the preparation of this varnish by the 
 new method here indicated, will admit of its being applied to all 
 coloured grounds which require solidity, pure whites alone excepted ; 
 painted boxes, therefore, and all small articles, coloured or not 
 coloured, whenever it is required to make the veins appear in all the 
 richness of their tones, call for the application of this varnish, which 
 produces the most beautiful effect, and which is more durable than 
 turpentine varnishes composed with other resinous substances. 
 
 Fat Amber Varnish. 
 
 16 oz. of amber, coarsely powdered, 
 
 2 oz. of Venice turpentine, or gum lac, 
 
 10 oz. of prepared linseed oil, and 
 16 oz. of essence of turpentine. 
 
 The circumstances of the process are the same as those prescribed 
 for the preparation of the camphorated copal varnish. 
 
 This varnish was formerly much used ; but it has given place, in 
 pa/t, to that of copal, which is preferred on account of its being less 
 coloured. Watin introduces more essence and less linseed oil 5 
 experience and long practice are the only authority on which I recom- 
 mend the adoption of the present formula. 
 
 Amber Varnish with Essence of Turpentine. 
 
 6 or 7 oz. of liquefied amber, and separated from 
 the oily portions which alter its consistence. 
 Reduce the amber to powder, and if the operation of pounding forms 
 it into a paste, break it with your fingers : then mix it with the 
 essence, and heat the whole in a balneum mariae. It will speedily 
 dissolve, and the essence will take up, at the least, a fourth part of 
 its weight of the prepared amber. 
 
 When one coating of it is applied to white smooth wood, but 
 
APPENDIX. 
 
 74^ 
 
 without any preparation, it forms a very pure and very durable 
 glazing, which speedily dries, but slower than copal varnish. 
 
 Fal Amhej'j or Copal Varnish, 
 
 4 oz. of amber or copal of one fusion, 
 
 10 oz. of essence of turpentine, and 
 10 oz. of drying linseed oil. 
 
 Pot the whole into a pretty large matrass, and expose it to the 
 heat of a balneum mariae, or move it over the surface of an uncovered 
 chafl 6 ng-dish, but without flame, and at the distance from it of two 
 or three inches. When the solution is completed, add still a little 
 copal or amber to saturate the liquid ; then pour the whole on a 
 filter prepared with cotton, and leave it to clarify by rest. If the 
 varnish is too thick, add a little warm essence to prevent the separa- 
 tion of any of the amber. 
 
 This varnish is coloured, but far less so than those composed by 
 the usual methods. When spread over white wood, without any 
 preparation, it forms a solid glazing, and communicates a slight tint 
 to the wood. 
 
 If it be required to charge this varnish with more copal, or prepared 
 amber, the liquid must be composed of tw'o parts of essence for one 
 of oil. 
 
 Cojnpound Mastic Varnish. 
 
 32 oz. of pure alcohol, 
 
 6 oz. of purified mastic, 
 
 3 oz. of gum sandarac, 
 
 3 oz. of very clear Venice turpentine, and 
 
 4 oz. of glass, coarsely pounded. 
 
 Reduce the mastic and sandarac to fine powder 5 mix this powder 
 with white glass, from which the finest parts have been separated by 
 means of a hair sieve j put all the ingredients, with alcohol, into a 
 short necked matrass, and adapt to it a stick of white wood, rounded 
 at tfie end, and of a length proportioned to the height of the matrass, 
 that it may be put in motion. Expose the matrass in a vessel filled 
 W’ith water, made at first a little warm, and which must afterwards 
 be maintained in a state of ebullition for one or two hours. The 
 matrass may be made fast to a ring of straw. 
 
 When the solution seems to be sufficiently extended, add tlie tur- 
 pentine, which must be kept separately in a phial or a pot, and which 
 must be melted, by immersing it for a moment in a balneum marise. 
 The matrass must be still left in the water for half an hour, at the 
 end of which it is taken off 5 and the varnish is continually stirred 
 till it is somewhat cool. Next day it is to be drawn off, and filtered 
 through cotton. By these means it will become exceedingly limpid. 
 
 The addition of glass may appear extraordinary j but this substance 
 divides the parts of the mixture, which have been made with the dry 
 it)gredieuts, and it retains the same quality when placed over the fire. 
 It therefore obviates with success two inconveniences, which are 
 exceedingly troublesome to those who compose varnishes. In the 
 first place, by dividing the matters, it facilitates the action of the 
 
APPENDIX. 
 
 743 
 
 alcohol ; and in the second its weight, which surpasses that of resins, 
 prevents these resins from adhering to the bottom of the matrass, and 
 also the coloration acquired by the varnish when a sand-bath is em- 
 ployed, as is commonly the case. 
 
 The application of this varnish is suited to articles belonging to the 
 toilette, such as dressing-boxes, cut paper-works, &c. The following 
 possess the same brilliancy and lustre j but they have more solidity, 
 and are exceedingly drying. 
 
 Camphorated Mastic Varnish for Paintings. 
 
 12 oz. of mastic, cleaned and washed, 
 
 1|- oz. of pure turpentine, 
 
 § oz. of camphor, 
 
 5 oz. of white glass, pounded, and 
 36 oz. of ethereous essence of turpentine. 
 
 Make the varnish according to the method indicated for compound 
 mastic varnish of the first genus. The camphor is employed in 
 pieces, and the turpentine is added when the solution of the resin is 
 completed. But if the varnish is to be applied to old paintings, or 
 paintings which have been already varnished, the turpentine may be 
 suppressed, as this ingredient is here recommended only in cases of a 
 first application to new paintings, and just freed from white of egg 
 varnish. 
 
 The etherous essence recommended for varnish, is that distilled' 
 slowly, without any intermediate substance, according to the second 
 process already given for its rectification. 
 
 The question by able masters, respecting the kind of varnish pro- 
 per to be employed for paintings, has never yet been determined. 
 
 Some artists, who have paid particular attention to this object, 
 make a mystery of the means they employ to obtain the desired effect. 
 The real end may be accomplished by giving to the varnish, destined 
 for painting, pliability and softness, without being too solicitous in 
 regard to what may add to its consistence or its solidity. The latter 
 quality is particularly requisite in varnishes which are to be applied 
 to articles much exposed to friction, such as boxes, furniture, &c. 
 
 To make Painter s Cream. — Painters, who have long intervals be- 
 tween their periods of labour, are accustomed to cover the parts they 
 have painted with a nreparation which preserves the freshness of the 
 colours, and which they can remove when they resume their work. 
 This preparation is as follows : 
 
 3 oz. very clear nut oil, 
 
 -i- oz. mastic in tears, pulverized, and 
 i oz. sal satnrni, in powder, (acetate of lead.) 
 
 Dissolve the mastic oil over a gentle fire, and pour the mixture into 
 a marble mortar, over the pounded salt of lead ; stir it with a wooden 
 pestle, and add water in small quantities, till the matter assume the 
 appearance and consistence of cream, and refuse to admit more water. 
 
 Sandarac Varnish. 
 
 8 oz. gum sandarac. 
 
744 
 
 appendix 
 
 2 oz. pounded mastic, 
 
 4 oz. clear turpentine, 
 
 4 oz. pounded glass, and 
 32 oz. alcohol. 
 
 Mix, and dissolve as before. 
 
 Compound Sandarac V irnish. 
 
 3 oz. pounded copal of an amber colour, once liquefied, 
 
 6 oz. gum sandarac, 
 
 3 oz. mastic, cleaned, 
 
 2i oz. clear turpentine, 
 
 4 oz. pounded glass, and 
 32 oz. pure alcohol. 
 
 Mix these ingredients, and pursue the same method as above. 
 
 This varnish is destined for articles subject to friction, such as 
 furniture, chairs, fan-sticks, mouldings. See. and even metals, to which 
 it may be applied with success. The sandarac gives it great durability. 
 
 Camphorated Sandarac Varnish for cut Paper Wbrhs, Dressing 
 Boxes, Sfc. 
 
 No. 1,— 6 oz. gum sandarac, 
 
 4 oz. gum elemi, 
 
 1 oz. gum anima, ^ 
 
 § oz. camphor, 
 
 4 02 . pounded glass, and 
 32 oz. pure alcohol. 
 
 Make the varnish according to the directions already given. The 
 soft resins must be pounded with the dry bodies. The camphor is 
 to be added in pieces. 
 
 No 2. — 6 oz. gallipot, or white incense, 
 
 2 oz. gum animi, 
 
 2 oz. gum elemi, 
 
 4 oz. pounded glass, and 
 32 oz. alcohol. 
 
 Make the varnish with the precautions indicated for the compound 
 mastic varnish. 
 
 The two last varnishes are to be used for ceilings and wainscots, 
 coloured or not coloured : they may even be employed as a covering 
 to parts painted with strong colours. 
 
 Spirituous Sandarac Varnish for Wainscot ting, small Articles of 
 Furniture^ Balustrades, and inside Railing. 
 
 No. 1. — 6 oz, of gum sandarac, 
 
 2 oz. of shell lac, 
 
 4 oz. of colophonium, or resin, 
 
 4 oz. of white glass powdered, 
 
 4 oz. of clear turpentine, and 
 32 oz. of pure alcohol. 
 
 Dissolve the varnish according to the directions given for com- 
 pound mastic varnish. 
 
 This varnish is sufficiently durable to be applied to articles destined 
 
APPENDIX. 745 
 
 to daily and continual use. Varnishes composed with copal ought, 
 however, in these cases, to be preferred. 
 
 No. 2 — There is another composition which, without forming part 
 of the compound varnishes, is employed with success for giving a 
 polish and lustre to furniture made of wood : wax forms the basis 
 of it. 
 
 Many cabinet-makers are contented with waxing common furniture, 
 such as tables, chests of drawers, &c. This covering, by means of 
 repeated friction, soon acquires a polish and transparency which re- 
 sembles those of varnish. Waxing seems to possess qualities pecu- 
 liar to itself i but, like varnish, it is attended with inconveniences as 
 well as advantages. 
 
 Varnish supplies better the part of glazing ; it gives a lustre to 
 the wood which it covers, and heightens the colours of that destined, 
 in particular, for delicate articles. These real and valuable advan- 
 tages are counterbalanced by its want of consistence j it yields too 
 easily to the shrinking or swelling of the wood, and rises in scales, 
 or slits, on being exposed to the slightest shock. These accidents can 
 be repaired only by new strata of varnish, which render application 
 to the varnisher necessary, and occasion trouble and expense. 
 
 Waxing stands shocks ; but it does not possess, in the same degree 
 as varnish, the property of giving lustre to the bodies on which it is 
 applied, and of heightening their tints. The lustre it communicates 
 is dull, but this inconvenience is compensated by the facility with 
 which any accident that may have altered its polish can be repaired, 
 by rubbing it with a piece of fine cork. There are some circum- 
 stances, therefore, under which the application of wax ought to be 
 preferred to that of varnish. This seems to be the case in particular 
 with tables of walnut-tree wood, exposed to daily use, chairs, mould- 
 ings, and for all small articles subject to constant employment. 
 
 But as it is of importance to make the stratum of wax as thin as 
 possible in order that the veins of the wood may be more apparent, 
 the following process will be acceptable to the reader. 
 
 Melt over a moderate fire, in a very clean vessel, two ounces of 
 white or yellow waxj and, when liquefied, add four ounces of 
 good essence of turpentine. Stir the whole until it is entirely cool, 
 and the result will be a kind of pomade fit for waxing furniture, and 
 which must be rubbed over them according to the usual method. 
 The essence of turpentine is soon dissipated j but the wax, which by 
 its mixture is reduced to a state of very great division, may be ex- 
 tended with more ease, and in a more uniform manner. * The es- 
 sence soon penetrates the pores of the wood, calls forth the colour of 
 it, causes the wax to adhere better, and the lustre which thence re- 
 sults is equal to that of varnish, without having any of its incon- 
 veniences. 
 
 Coloured Varnish for Violins, and other stringed Instruments, also 
 for Plum-tree, Mahogany, and Rose-wood, 
 
 4 oz. gum sandarac, 
 
 2 oz. seed lac. 
 
746 
 
 APPENDIX. 
 
 oz. mastic, 
 
 1 oz. Benjamin in tears, 
 
 4 oz. pounded glass, 
 
 2 oz. \’’enice turpentine, and 
 .32 oz. pure alcohol. 
 
 The gum sandarac and lac render this varnish dural la : it may be 
 coloured with a little saffron or dragon’s blood. 
 
 Fat Famish of a gold colour, 
 
 8 oz. amber, 
 
 2 oz. gum lac, 
 
 8 oz, drying linseed oil, and 
 If) oz. essence of turpentine. 
 
 Dissolve separately the gum lac, and then add the amber, prepar- 
 ed and pulverized, with the linseed oil and essence very warm. When 
 the whole has lost part of its heat, mix in relative proportions, tinc- 
 tures of annatto, of terra merita, gum guttae, and dragon’s blood. 
 This varnish, when applied to white metals, gives them a gold colour. 
 
 Fat Turpentine or Golden Famish^ being a mordant to gold and 
 dark colours. 
 
 16 oz. boiled linseed oil, 
 
 8 oz. Venice turpentine, and 
 
 5 oz. Naples yellow. 
 
 Heat the oil wdth the turpentine 3 and mix the Naples yellow pul- 
 verized. 
 
 Naples yellow is an oxide of lead, the composition of which will 
 be given when we come to treat of colouring substances. It is sub- 
 stituted here for resins, on account of its drying qualities, and in par- 
 ticular of its colour, which resembles that of gold j great use is 
 made of the varnish in applying gold leaf. 
 
 The yellow, however, may be omitted when this species of varnish 
 is to be solid and coloured coverings. In this case an ounce of li- 
 tharge to each pound of composition may be substituted in its stead, 
 without this mixture doing any injury to the colour which is to con- 
 stitute the ground, f!a teinte dure.J 
 
 Turners' Famish for Box Wood, 
 
 5 oz. seed lac, 
 
 2 oz. gum sandarac, 
 l-§ oz. gum elemi, 
 
 2 oz. Venice turpentine, 
 
 .5 oz. pounded glass, and 
 24 oz. pure alcohol. 
 
 The artists of St. Claude do not all employ this formula, which 
 required to be corrected on account of its too great dryness, which 
 is here lessened by the turpentine and gum elemi. This composition 
 is secured from cracking, which disfigures these boxes after they had 
 been used for some months. 
 
 No. 2. — Other turners employ the gum lac united to a little elemi 
 and turpentine digested some months in pure alcohol exposed to the 
 sun. If this method be followed, it will be proper to substitute for 
 
APPENDIX. 
 
 747 
 
 the sandarac, the same quantity of gum lac reduced to powder^ and 
 not to add the turpentine to the alcohol, v, Inch ought to be exceed- 
 ingly pure, till towards the end of the infusion. 
 
 Solar infusion requires care and attention. Vessels of a sufficient 
 size to allow the spirituous vapours to circulate freely ought to be 
 employed, because it is necessary that the vessels should be closely 
 shut. Without this precaution the spirits would become weakened, 
 and abandon the resin which they laid hold of during the first days 
 of exposure. This perfect obituration will not admit of the vessels 
 being too full. 
 
 In general, the varnishes applied to articles which may be put into 
 the lathe acquire a great deal of brilliancy by polishing j a piece of 
 woollen cloth is sufficient for the operation. If turpentine predomi- 
 nates too much in these compositions the polish does not retain its 
 lustre, because tlie heat of the hands is capable of softening the sur- 
 face of the varnish, and in this state it readily tarnishes. 
 
 T 1 varnish Dressing Boxes . — The most of spirit of wine varnishes 
 are destined for covering preliminary preparations, which have a cer- 
 tain degree of lustre. They consist of cement, coloured or not co- 
 loured, charged with landscapes and figures cut out in paper, which 
 produces an effect under the transparent varnish : most of the dres- 
 sing boxes, and other small articles of the same kind, are covered 
 with this particular composition, which, in general, consists of 
 three or four coatings of Spanish white pounded in water, and mixed 
 up w'ith parchment glue. The first coating is smoothed with pum- 
 mice-stone, and then polished with a piece of new linen and water. 
 The coating in this state is fit to receive the destined colour, after it 
 has been ground with w^ater, and mixed with parchment glue diluted 
 with water. The cut figures with which it is to be embellished, are 
 then applied, and a coating of gum, or fish-glue is spread over them, 
 to prevent the varnish from penetrating to the preparation, and from 
 spoiling the figures. The operation is finished by applying three or 
 four coatings of varnish, which, wffien dry, are polished with tripoli 
 and water, by means of a piece of cloth. A lustre is then given to 
 the surface with starch and a bit of doe-skin, or very soft cloth. 
 
 Gallipot Varnish. 
 
 12 oz. gallipot, or w’hite incense, 
 
 5 oz. white glass, pounded, 
 
 2 oz. Venice turpentine, and 
 32 oz. essence of turpentine. 
 
 Make the varnish after the white incense has been pounded with glass. 
 
 Some authors recommend mastic or sandarac in the room of galli- 
 pot 5 but the varnish is neither more beautiful nor more durable. 
 When the colour is ground with the preceding varnish, and mixed 
 up w’ith the latter, which, if too thick, is thinned with a little es- 
 sence, and which is applied immediately, and without any sizing, to 
 boxes and other articles, the coatings acquire sufficient strength to 
 resist the blows of a mallet. But if the varnish be applied to a sized 
 colour, it must be covered wdth a varnish of the first or second genus. 
 
APPENDIX. 
 
 748 
 
 Mastic Gallipot Varnish, for grinding Colours. 
 
 4 OE. new gallipot, or white incense,' 
 
 2 oz. raastic, 
 
 6 oz. Venice turpentine, 
 
 4 oz. pounded glass, and 
 32 oz. essence of turpentine. 
 
 When the varnish is made with the precautions already indicated, 
 add prepared nut oil or linseed oil two ounces. 
 
 The matters ground with this varnish dry more slowly j they are 
 then mixed up with the following varnish, if it be for common paint- 
 ing, or with particular varnishes destined for colours and for grounds 
 
 Mordant Varnish for Gilding. 
 
 1 oz. of mastic, 
 
 1 oz. of gum sandarac, 
 
 ^ oz. of gum gattae, 
 
 J oz. of turpentine, and 
 6 oz. of essence of turpentine. 
 
 Some artists who make use of mordant, substitute for the turpen- 
 tine an ounce of the essence of lavender, which renders this com- 
 position still less drying. 
 
 In general, the composition of mordants admits of modifications, 
 according to the kind of work for which they are destined. The ap- 
 plication of them, however, is confined chiefly to gold. When it is 
 required to fill up a design with gold leaf on any ground whatever, the 
 composition which is to serve as the means of union between the 
 metal and the ground, ought to be neither too thick nor too fluid j 
 because both these circumstances are equally injurious to delicacy in 
 the strokes ; it will be requisite also that the composition should not 
 dry till the artist has completed his design. 
 
 Other Mordants. No. 1. — Some prepare their mordants with Jew’s 
 pitch and drying oil diluted with essence of turpentine. They employ 
 it for gilding pale gold, or for bronzing. 
 
 Other artists imitate the Chinese, and mix with their mordants 
 colours proper for assisting the tone which they are desirous of giving 
 to the gold, such as yellow, red, &c. 
 
 Others employ merely fat varnish, to which they add a little red 
 oxide of lead (minium). 
 
 Others make use of thick glue, in which they dissolve a little 
 honey. This is what they call batture. When they are desirous of 
 heightening the colour of the gold, they employ this glue, to which 
 the gold leaf adheres exceedingly well. 
 
 No. 2. — The qualities of the following are fit for every kind of ap- 
 plication, and particularly to metals. Expose boiled oil to a strong 
 heat in a pan : when a black smoke is disengaged from it, set it 
 on fire, and extinguish it a few moments after by putting on the 
 cover of the pan. Then pour the matter still warm, into a heated 
 bottle, and add to it a little essence of turpentine. This mordant 
 dries very speedily ; it has body and adheres to, and strongly retains, 
 gold leaf, when applied to wood, metals, and other substances. 
 
APPENDIX. 
 
 749 
 
 Varnish for Pales and coarse Wood-work. — Take any quantity of 
 lar, and grind it with as much Spanish brown as it will bear, without 
 rendering it too thick to be used as a paint or varnish, and then 
 spread it on the pales, or other wood, as soon as convenient, for it 
 quickly hardens by keeping. 
 
 This mixture must be laid on the wood to be varnished by a large 
 brush, or house painter’s tool j and the work should then be kept as 
 free from dust and insects as possible, till the varnish be thoroughly 
 dry. It will, if laid on smooth wood, have a very good gloss, and is an 
 excellent preservation of it against moisture ^ on which account, as 
 well as its being cheaper, it is far preferable to painting, not only for 
 pales, but for weather-boarding, and all other kinds of wood-work 
 for grosser purposes. Where the glossy brown colour is not liked, 
 the work may be made of a greyish brown, by mixing a small pro- 
 portion of white lead, or whiting and ivory black, with the Spanish 
 brown. 
 
 A Black Varnish for Old Straw or Chip Hats. 
 
 J oz. of best black sealing wax, and 
 2 oz. of rectified spirit of wine. 
 
 Powder the sealing-wax, and put it with the spirit of wine, into 
 a* four-ounce phial ; digest them in a sand heat, or near a fire, till 
 the wax is dissolved ; lay it on warm with a fine soft hair-brush, be- 
 fore a fire or in the sun. It gives a good stiffness to old straw hats, 
 and a beautiful gloss, equal to new, and resists wet. 
 
 To make Varnish for coloured Drawings. 
 
 1 oz. of Canada balsam, and 
 
 2 oz. of spirit of turpentine. — Mix them together. 
 
 Before this composition is applied, the drawing or print should be 
 
 sized with a solution of isinglass in water j and when dry, apply 
 the varnish with a camel’s-hair brush. 
 
 To make Varnish for Wood, which resists the action of Boiling Water. 
 -—Take a pound and a half of linseed-oil, and boil it in a red copper 
 vessel, not tinned, holding suspended over it, in a small linen bag, 5 
 oz. of litharge, and 3 oz. of pulverized minium ; taking care that the 
 bag does not touch the bottom of the vessel. Continue the ebullition 
 until the oil acquires a deep brown colour ; then take away the bag, 
 and substitute another in its place, containing a clove of garlic j con- 
 tinue the ebullition, and renew the clove of garlic seven or eight 
 times, or rather put them all in at once. 
 
 Then throw into the vessel a pound of yellow amber, after having 
 melted it in the following manner : — Add to the pound of amber, 
 well pulverized, two ounces of linseed oil, and place the whole on a 
 strong fire. When the fusion is complete, pour it boiling into the 
 prepared linseed-oil, and continue to leave it boiling for two or three 
 minutes, stirring the whole up well. It is then left to settle ; the 
 composition is decantered and preserved, when it becomes cold, in 
 well-corked bottles. 
 
 After polishing the wood on which this varnish is to be applied, 
 give to the wood the colour required ; for instance, for walnut wood, 
 a slight coat of a mixture of soot with the essence of turpentine. 
 
ArrRNOJX. 
 
 750 
 
 When this colonr is perfectly dry, give it a coat of varnish with a 
 fine sponge, in order to spread it xary equal j repeat these coats 
 four times, taking care always to let the preceding coat be dried. 
 
 To Varnish Drawings and Card-work.-^^oW some clear parchment 
 cuttings in water, in a glazed pipkin, till they produce a very clear 
 size. Strain it, and keep it for use. 
 
 Give the work two coats of the size, passing the brush quickly over 
 the work, not to disturb the colours. 
 
 To prepare a Composition for making coloured Drawings and 
 Prints resemble Paintings in Oil. 
 
 1 oz. of Canada balsam, and 
 
 2 oz. of spirit of turpentine.— Mixt together. 
 
 Before this composition is applied, the drawing or print should be 
 
 sized with a solution of isinglass in water, and when dry, apply the 
 varnish with a camel-hair brush. 
 
 To Varnish Harps and Dulcimers. — Prepare the wwk with size and 
 red ochre, then take ochre, burnt umber, and red lead, well ground, 
 and mix up a dark brown colour in turpentine varnish, adding as 
 much oil of turpentine that the brush may just be able to pass over 
 the work fair and even. While yet wet, take a muslin sieve, and sift 
 as much Dutch metal, previously powdered, upon it, as is requisite 
 to produce the effect, after which, varnish and polish it. 
 
 To Varnish G7as5. —Pulverize a quantity of gum adragant, and let 
 it dissolve for twenty-four hours in the white of eggs well beat up j 
 then rub it gently on the glass v\dth a brush. 
 
 To Varnish Balloons. No. 1. — The compositions for varnishing 
 balloons have been variously modified 3 but, upon the whole, the 
 most approved appears to be the bird-lime varnish of M. Faujas St, 
 Fond, prepared after M. Cavallo’s method as follows : In order to 
 
 render linseed oil drying, boil it with 2 ounces of sugar of lead, and 3 
 ounces of litharge, for every pint of oil, till they are dissolved, which 
 may be in half an hour. Then put a pound of bird-lime, and half a 
 pint of the drying oil, into an iron or copper vessel, whose capaeity 
 should equal about a gallon, and let it boil very gently over a slow 
 charcoal fire, till the bird-lime ceases to crackle, which will be in 
 about half, or three-quarters, of an hour ; then pour upon it two 
 and a half pints more of the drying oil, and let it boil about an 
 hour longer 3 stirring it frequently with an iron or wooden spatula. 
 As the varnish, whilst boiling, and especially when nearly ready, 
 swells very much, care should be taken to remove, in those cases, the 
 pot from the fire, and to replace it w'hen the varnish subsides 3 other- 
 wise it will boil over. Whilst the stuff is boiling, the operator should 
 occasionally examine whether it has boiled enough, which may be 
 know’n by observing whether, when rubbed between two knives, 
 which are then to be separated from one another, the varnish forms 
 threads between them, as it must then be removed from the fire. 
 When nearly cool, add about an equal quantity of oil of turpentine. 
 In using the varnish, the stuff must be stretched, and the varnish ap- 
 plied lukewarm. In 24 hours it w ill dry.” 
 
APPENDIX. 
 
 751 
 
 No. 2. As the elastic resin, known by the name of Indian rubber, 
 has been much extolled for a varnish, the following method of making 
 it, as practised by M. Blanchard, may not prove unacceptable. — 
 Dissolve elastic gum, cut small, in five times its weight of rectified 
 essential oil of turpentine, by keeping them some days together ; 
 then boil 1 ounce of this solution in 8 ounces of drying linseed oil for 
 a few minutes j strain the solution, and use it warm. 
 
 To Varnish Rarefied Air Balloons. — With regard to the rarefied-air 
 machines, M. Cavallo recommends, first, to soak the cloth in a solu- 
 tion of sal-ammoniac and common size, using one pound of each to 
 every gallon of water ; and when the cloth is quite dry, to paint it 
 over on the inside with some earthy colour, and strong size or 
 glue. When this paint has dried perfectly, it will then be proper to 
 cover it wdth oily varnish, which miglit dry before it could penetrate 
 quite through the cloth. Simple drying linseed oil will answer the 
 purpose as well as any, provided it be not very fluid. 
 
 To Paint Sail- Cloth i &;c. so as to be pliant, durable, and impervi- 
 ous to Water. — This process, which is extracted from the Transactions 
 of the Society of Arts, is now universally practised in the public 
 dock-yards. 
 
 The paint usually laid upon canvas hardens to such a degree as to 
 crack, and eventually to break the canvas, which renders it unser- 
 viceable in a short time : but the canvas painted in the new manner 
 is .so superior, that all canvas used in the navy is thus prepared ; and 
 a saving of a guinea is made in every one himdred square yards of 
 canvas so painted. 
 
 The old mode of painting canvas, w’as to w^et the canvas, and 
 prime it with Spanish brown j then to give it a second coat of a cho- 
 colate colour, made by mixing Spanish iDrown and black paint : and, 
 lastly, to finish it with black. 
 
 The new method is to grind 96 lbs. of English ochre with boiled 
 oil, and to add 16 lbs. of black paint, which mixture forms an indif- 
 ferent black. A pound of yellow soap dissolved in six pints of water 
 over the fire, is mixed, while hot, v\ith the paint. This compo- 
 sition is then laid upon the canvas, (without being wetted, as in the 
 usual way,) as stiff as can conveniently be done with the brusli, so as 
 to form a smooth surface j the next day, or still better, on the second 
 day, a second coat of ochre and black (without any, or but a very 
 small portion of soap) is laid on, and allowing this coat an interme- 
 diate day for drying, the canvas is then finished with black paint as 
 usual. Three days being then allowed for it to dry and harden, it 
 does not stick together when taken down, and folded in cloths con- 
 taining 60 or 70 yards each j and canvas finished entirely witli the 
 composition, leaving it to dry one day between each coat, will not 
 stick together, if laid in quantities. 
 
 It has been ascertained from actual trials, that the solution of yel- 
 low soap is a preservative to red, yellow, and black paints, when 
 ground in oil and put into casks, they acquire no improper hard- 
 
APPENDIX. 
 
 752 
 
 ness, and dry in a remarkable manner when laid on with the brash, 
 without the use of the usual drying articles. 
 
 It is surprising that the adoption of soap, which is so well known 
 to be miscible with oily substances, or, at least, the alkali of which 
 it is composed, has not already been brought into use in the compo- 
 sition of oil colours. 
 
 Coloured Compositions for rendering Linen and Cloth impenetralle 
 to Water . — Begin by washing the stuff with hot water ; then dry and 
 rub it between the hands until such time as it becomes perfectly sup- 
 ple ; afterwards spread it out by drawing it into a frame, and 
 give it, with the aid of a brush, a first coat, composed of a mixture 
 of eight quarts of boiling linseed oil, 15 grammes of calcined amber 
 and acetate of lead, (of each 7 ^grammes) to which add grammes 
 of lamp-black. For the second coat use the same ingredients as 
 above? except the calx of lead. This coat will give a few hours, ac- 
 cording to the season j afterwards take a dry plasterer’s brush, and 
 rub the stuff strongly with it, when the hair by this operation will 
 become very smooth. The third and last coat will give a perfect and 
 durable jet black. 
 
 Or rather take 12 quarts of boiling linseed oil, 30 grammes of am- 
 ber, 15 grammes of acetate of lead, 7^ sulphate of zinc, 15 Prussian 
 blue, and 7\ verdigris ; mix them very fine with a little oil, and add 
 120 grammes of lamp-black. These coats are used at discretion, as 
 is done with painting. 
 
 To Thicken Linen Cloth for Screens and Bed Testers* — Grind whi- 
 ting with zinc, and to prevent cracking, add a little honey to it 5 
 then take a soft brush, and lay it upon the cloth, and so do two or 
 three times, suffering it the mean while to dry between layings on, 
 and for the last laying, smooth it over with Spanish white, ground 
 with linseed oil, the oil being first heated, and mixed with a small 
 quantity of the litharge of gold, the better to endure the weather, 
 and so it will be lasting. 
 
 Common Wax, or Varnished Cloth, — The manufacture of this kind 
 of cloth is very simple. The cloth and linseed oil are the principal 
 articles required for the establishment. Common canvas, of an open 
 and coarse texture, is extended on large frames, placed under sheds, 
 the sides of which are open, so as to afford a free passage to the ex- 
 ternal air. The manner in which the cloth is fastened to these franaes 
 is as follows : it is fixed to each side of the frame by hooks which 
 catch the edge of the cloth, and by pieces of strong packthread pass- 
 ing through holes at the other extremity of the hooks, which are tied 
 round moveable pegs placed in the lower edge of the frame. The me- 
 chanism by which the strings of a violin are stretched or unstretched, 
 will give some idea of the arrangement of the pegs employed for ex- 
 tending the cloth in this apparatus. By these means the cloth can 
 be easily stretched or relaxed, when the oily varnish has exercised an 
 action on its texture in the course of the operation. The whole being 
 thus arranged, a liquid paste made with drying oil, which may be 
 varied at pleasure, is applied to the cloth. 
 
APPENDIX. 
 
 753 
 
 To make Liquid Paste with Drying Oil. — Mix Spanish white or 
 tobacco-pipe clay, or any other argillaceous matter, with w’ater, and 
 leave it at rest some hours, which will be sufficient to separate the 
 argillaceous parts, and to produce a sediment. Stir the sediment with 
 a broom, to complete the division of the earth j and after it has 
 rested some seconds, decant the turbid water into an earthen or 
 wooden vessel. By this process the earth will be separated from the 
 sand and other foreign bodies, which, are precipitated, and which 
 must be thrown away. If the earth has been washed by the same 
 process, on a large scale, it is divided by kneading it. The super- 
 natant water is thrown aside, and the sediment placed, in sieves, on 
 pieces of cloth, where it is suffered to drain: it is then mixed up with 
 oil rendered drying by a large dose of litharge, that is about a fourth 
 of the weight of the oil. The consistence of thin paste being given 
 to the mixture, it is spread over the cloth by means of an iron spatu- 
 la, the length of which is equal to that of the breadth of the cloth. 
 This spatula performs the part of a knife, and pushes forward the 
 excess of matter above the quantity sufficient to cover the cloth. 
 When the first stratum is dry, a second is applied. The inequalities 
 produced by the coarseness of the cloth, or by an unequal extension 
 of the paste, are smoothed down with pumice-stone. The pumice- 
 stone is reduced to powder, and rubbed over the cloth with a piece of 
 soft serge or cork dipped in water. The cloth must then be well 
 washed in water to clean it j and after it is dried, a varnish of guin 
 lac dissolved in linseed oil boiled with turpentine, is to be applied 
 to it. 
 
 This preparation produces yellowish varnished cloth. When 
 wanted black, mix lamp-black with the Spanish white, or tobacco- 
 pipe clay, which forms the basis of the liquid paste. Various shades 
 of grey may be obtained, according to the quantity of .lamp-black 
 which is added. Umber, Cologne earth, and different ochry argilla- 
 ceous earths, may be used to vary the tints, without causing any 
 addition to the expense. 
 
 To prepare jine Printed Varnished Cloths. — The process just de- 
 scribed for manufacturing common varnished and polished cloths, 
 may serve to give some idea of that employed for making fine cloths 
 of the same kind, decorated with a coloured impression. The manu- 
 factories of Germany have varnished cloths embellished with large 
 and small subjects, figures, and landscapes, well executed, and which 
 are destined for covering furniture subjected to daily use. 
 
 This process, which is only an improvement of the former, requires 
 a finer paste, and cloth of a more delicate texture. The stratum of 
 paste is applied in the same manner, and when dry and polished, the 
 cloth is taken from the frame and removed to the painter’s table, 
 where the art of the colourist and designer is displayed under a 
 thousand forms ; and, as in that of printed cottons, exhibits a rich- 
 ness of tints, and a distribution of subjects, which discover taste, 
 and ensure a ready sale for the articles manufactured. 
 
 The processes, however, employed in these two arts to extract the 
 
 3 C 
 
APPENDIX. 
 
 754 
 
 colouring parts are not the same. In the art of cotton printing the 
 colours are extracted by the bath, as in that of dyeing. In printing 
 varnished cloths, the colouring parts are the result of the union of 
 drying oil mixed with varnish 5 and the different colours employed in 
 oil painting or painting in varnish. 
 
 The varnish applied to common oil cloth is composed of gum lac 
 and drying linseed oil j but that destined for printed varnished cloths 
 requires some choice, both in regard to the oil and the resinous matter 
 which gives it consistence. Prepared oil of pinks and copal form a 
 varnish very little coloured, pliable, and solid. 
 
 To prepare Varnished Silk. No. 1. — Varnished silk, for making 
 umbrellas, capots, coverings for hats, &c. is prepared in the same 
 manner as the varnished and polished cloths already described, but 
 with some variation in the liquid paste or varnish. 
 
 If the surface of the silk be pretty large, it is made fast to a 
 wooden frame furnished with hooks and moveable pegs, such as that 
 used in the manufacture of common varnished cloths. A soft paste, 
 composed of linseed oil, boiled with a fourth part of litharge j to- 
 bacco-pipe clay, dried and sifted through a silk sieve, 16 parts ; 
 litharge ground on porphyry with water, dried and sifted in the same 
 manner, 3 parts j and lamp-black, 1 part. This paste is then spread 
 in an uniform manner over the surface of the silk, by means of a 
 long knife, having a handle at each extremity. In summer, twenty- 
 four hours are sufficient for its desiccation. When dry, the knots 
 produced by the inequalities of the silk are smoothed with pumice- 
 stone. This operation is performed with water, and when finished, 
 the surface of the silk is w ashed. It is then suffered to dry, and flat 
 copal varnish is applied. 
 
 If it be intended to polish this varnish, apply a second stratum j 
 after whicli polish it with a ball of cloth and very fine tripoli. The 
 varnished silk thus made, is very black, exceedingly pliable, and has a 
 fine polish. It may be rumpled a thousand ways without retaining 
 any fold, or even the mark of one. It is light, and thereby proper 
 for coverings to hats, and for making cloaks and caps so useful to 
 travellers in wet weather. 
 
 No. 2. — A kind of varnished silk, wffiich has only a yellowish 
 colour, and wdiich suffers the texture of the stuff to appear, is pre- 
 pared with a mixture of 3 parts boiled oil of pinks, and 1 part of fat 
 copal varnish, which is extended wdth a coarse brush or a knife. Two 
 strata are sufficient when oil has been freed from its greasy particles 
 over a slow fire, or when boiled with a fourth part of its weight of 
 litharge. 
 
 The inequalities are removed by pumice-stone and water ; after 
 which the copal varnish is applied. This simple operation gives to 
 white silk a yellow colour, which arises from the boiled oil and the 
 varnish. 
 
 This varnished silk possesses all those qualities ascribed to certain 
 preparations of silk which are recommended to be worn as jackets by 
 persons subject to rheumatism. 
 
APPENDIX. 
 
 755 
 
 To recover Clear filth with a ley made of potash, 
 
 and the ashes of the lees of wine ; then take 48 ounces of potash, 
 and 1 6 of the above-mentioned ashes, and put them into 6 quarts of 
 water, and this completes the ley. 
 
 To polish Varnish. — This is effected with pumice-stone and Tripoli 
 earth. The pumice-stone must be reduced to an impalpable powder, 
 and put upon a piece of serge moistened with water j with this rub 
 lightly and equally the varnished substance. The tripoli must also 
 be reduced to a very fine powder, and put upon a clean woollen cloth, 
 moistened with olive oil, with which the polishing is to be performed. 
 The varnish is then to be wiped off with soft linen, and when quite 
 dry, cleaned with starch or Spanish white, and rubbed with the palm 
 of the hand. 
 
 ANTI-ATTRITION. 
 
 To prepare Anti-Attrition* — According to the specification of the 
 patent, this mixture consists of one hundred weight of plumbago, to 
 four hundred weight of hog’s-lard, or other grease 3 the two to be 
 well incorporated. The application is to prevent the effects of fric- 
 tion in all descriptions of engines or machines j and a sufficient 
 quantity must be rubbed over the surface of the axle, spindle, or 
 other part where the bearing is. 
 
 ASSAYING OF METALLIC ORES. 
 
 Before metallic ores are worked upon in the large way, it will be 
 necessary to enquire what sort of metal, and what portion of it, is 
 to be found in a determined quantity of the ore ; to discover whether 
 it will be worth while to extract it largely, and in what manner the 
 process is to be conducted, so as to answer that purpose. The know- 
 ledge requisite for this, is called the art of assaying. 
 
 Assay of Ores in the Dry Way* — The assaying of ores may be per- 
 formed either in the dry or moist way ; the first is the most ancient, 
 and, in many respects, the most advantageous, and consequently still 
 continues to be mostly used. 
 
 Assays are made either in crucibles with the blast of the bellows, 
 or in tests under a muffle. 
 
 Assay Weights. — The assay weights are always imaginary, some- 
 times an ounce represents an hundred weight on the large scale, and 
 is subdivided into the same number of parts, as that hundred weight 
 is in the great ; so that the contents of the ore obtained by the as- 
 say, shall accurately determine by such relative proportion, the quan- 
 tity to be expected from any weight of the ore on a larger scale. 
 
 Roasting the Ore. — In the lotting of the ores, care should be taken 
 to have small portions from different specimens, which should be pul- 
 
APPENDIX. 
 
 "■56 
 
 verized, and well mixed In an iron or brass mortar. The proper 
 quantity of the ore is now taken, and if it contain either sulphur or 
 arsenic, it is put into a crucible or test, and exposed to a moderate 
 degree of heat, till no vapour arises from it ; to assist this volatiliza- 
 tion, some add a small quantity of powdered charcoal. 
 
 Fluxes. To assist the fusion of the ores, and to convert the ex- 
 traneous matters connected with them into scoria, assayers use dif- 
 ferent kinds of fluxes. The most usual and efficacious materials for 
 the composition of these are, borax, tartar, nitre, sal ammoniac, 
 coraraou salt, glass, fluor-spar, charcoal powder, pitch, lime, litharge, 
 &c. in different proportions. 
 
 Crude of White Flux. — This consists of 1 part of nitre, and 2 of 
 tartar, well mixed together. 
 
 Black Flux. — The above crude flux detonates by means of kindled 
 charcoal, and if the detonation be effected in a mortar slightly covered, 
 the smoke that rises unites with the alkalised nitre and the tartar, 
 and renders it black. 
 
 Cornish Reducing Flux. 
 
 10 oz. of tartar, 
 
 3 oz. and 6 drachms of nitre, and 
 3 oz. and 1 drachm of borax.— Mixt well together. 
 
 Cornish Refining Flux. — Deflagrate, and afterwards pulverize, 2 
 parts of nitre, and 1 part of tartar. 
 
 The above fluxes answer the purpose very well, provided the ores 
 be deprived of all their sulphur j or, if they contain much earthy mat- 
 ters, because, in the latter case, they unite with them, and convert 
 them into a thin glass : but if any quantity of sulphur remain, these 
 fluxes unite with it, and form a liver of sulphur, which has the power 
 of destroying a portion of all the metals ; consequently, the assay 
 under such circumstances must be very inaccurate. The principal 
 difficulty in assaying appears to be in the appropriation of the pro- 
 per fluxes to each particular ore, and it likewise appears, that such a 
 discriminating knowledge can only be acquired from an extensive 
 practice, or from a knowledge of the chemical affinities and ac- 
 tions of different bodies upon each other. 
 
 In assaying, we are at liberty to use the most expensive materials 
 to effect our purpose, hence, the use of different saline fluxes ; but in 
 the working at large, such expensive means cannot be applied ; as by 
 such processes the inferior metals w'ould be too much enhanced in 
 value, especially in working very poor ores. In consequence of 
 which, in smelting works, where the object is the production of metals 
 in the great way, cheaper additions are used j such as lime-stone, 
 feldt-spar, fluor-spar, quartz, sand, slate, and slags. These are to 
 be chosen according to the different views of the operator, and the 
 nature of the ores. Thus iron ores, on account of the argillaceous 
 earth they contain, require calcareous additions, and the copper ores, 
 rather slags or vitrescent stones, than calcareous earth. 
 
 Humid Assay of Metallic Ores. — The mode of assaying ores for 
 their particular metals by the dry way, is deficient so far as relates to 
 
APPENDIX. 
 
 757 
 
 pointing out the different substances connected with them, because 
 they are always destroyed by the process for obtaining the assay 
 metal. The assay by the moist way is more correct, because the dif- 
 ferent substances can be accurately ascertained. The late celebrated 
 Bergman first communicated this method. It depends upon a 
 knowledge of the chemical affinities of different bodies for each 
 other j and must be varied according to the nature of the ore ; it is 
 very extensive in its application, and requires great patience and ad- 
 dress in its execution. To describe the treatment of each variety of 
 metallic ores, would take up too much of our room ; but to give a 
 general idea, we shall describe the procedure, both in the dry and the 
 humid way, on one species of all the different ores. 
 
 To Assay Iron Ores, No. 1. — The ore must be roasted till the 
 vapour ceases to arise. Take 2 assay quintals of it, and triturate 
 them with one of fluor-spar, f of a quintal of powdered charcoal, 
 and 4 quintals of decrepitated sea salt^ this mixture is to be put 
 into a crucible, lined on the inside with clay and powdered charcoal ; 
 a cover must be luted upon the crucible, and the crucible itself ex- 
 posed to a violent fire for an hour, and when it is cool, broken. 
 When, if the operation has been well conducted, the iron will be found 
 at the bottom of the crucible j to which must be added those metal- 
 lic particles, which may adhere to the scoria. The metallic particles 
 so adhering may be separated, by pulverising it in paper, and then 
 attracting them with a magnet. 
 
 No. 2. — If the ore should be in a calciform state, mixed with 
 earths, the roasting of it previous to assaying, if not detrimental, is 
 at least superfluous j if the earths should be of the argillaceous and 
 siliceous kind, to half a quintal of them, add of dry quick lime and 
 fluor-spar of each 1 quintal and reduced to powder, and mix them 
 with J of a quintal of powdered charcoal, covering the whole with 
 one ounce of decrepitated common salt j and expose the luted cruci- 
 ble to a strong forge fire for an hour and a quarter, then let it gradu- 
 ally cool, and let the regulus be struck off and weighed. 
 
 No. 3. — If the ore contain calcareous earth, there will be no occa- 
 sion to add quick lime j the proportion of the ingredients may be as 
 follows viz. 1 assay quintal of the ore ; 1 of decrepitated sea- 
 salt 5 \ of powdered charcoal j and 1 of fluor-spar, and the process 
 conducted as above. 
 
 There is a great difference in the reguli of iron j when the cold 
 regulus is struck with a hammer and breaks, the iron is called cold 
 short : if it break on being struck red-hot, ,it is called red short ; 
 but if it resist the hammer, both in its cold and ignited state, it is 
 good iron. 
 
 Humid Assay of Iron Ore.— To assay the calciform ores, which do 
 not contain much earthy or stony matter, they must be reduced to a 
 fine powder, and dissolved in the marine acid, and precipitated by 
 the Prussian alkali. A determinate quantity of the Prussian alkali 
 must be tried previously, to ascertain the portion of iron which it 
 will precipitate, and the estimate made accordingly. If the iron 
 
APPENDIX. 
 
 758 
 
 contain any considerable portion of zinc or manganese, the precipi- 
 tate must be calcined to redness, and the calx treated with dephlo- 
 gisticated nitrous acid, which will then take up only the calx of 
 zinc j when this is separated, the calx should again be treated either 
 with nitrous acid, with the addition of sugar, or with the acetous 
 acid, which will dissolve the manganese, if any j the remaining calx 
 of iron may then be dissolved by the marine acid, and precipitated 
 by the mineral alkali 3 or it may be farther calcined, and then weighed. 
 
 Zinc Ores. — Take the assay weight of roasted ore, and mix it 
 well with part of charcoal dust, put it into a strong luted earthen 
 retort, to which must be fitted a receiver 5 place the retort in a fur' 
 nace, and raise the fire, and continue it in a violent heat for two 
 hours, suffer it then to cool gradually, and the zinc will be found ad- 
 hering to the neck of the retort in its metallic form. 
 
 In the humid way. — Distil vitriolic acid over calamine to dryness 3 
 the residuum must be lixiviated in hot water 3 Avhat remains undis- 
 solved is siliceous earth ; to the solution add caustic volatile alkali, 
 which precipitates the iron and argil, but keeps the zinc in solution. 
 The precipitate must be re-dissolved in vitriolic acid, and the iron 
 and argil separated. 
 
 Tin Ores. — Mix a quintal of tin ore, previously washed, pulveriz- 
 ed, and roasted, till no arsenical vapour arises, with half a quintal or 
 calcined borax, and the same quantity of pulverized pitch 3 these are 
 to be put into a crucible moistened with charcoal-dust and water, 
 and the crucible placed in an air furnace. After the pitch is burnt, 
 give a Auolent heat for a quarter of an hour, and on withdrawing the 
 crucible, theregulus will be found at the bottom. If the ore be not 
 well washed from earthy matters, a larger quantity of borax will be 
 requisite, with some powdered glass 3 and if the ore contain iron, 
 some alkaline salt may be added. 
 
 In the humid way, — The assay of tin ores in the liquid way, was 
 looked upon as impracticable, till Bergman devised the following 
 method, which is generally successful. Let the tin ore be well sepa- 
 rated from its stony matrix, by well washing, and then reduced to 
 the most subtle powder 3 digest it in concentrated oil of vitriol, in a 
 strong heat for several hours, then, when cooled, add a small portion 
 of concentrated marine acid, and suffer it to stand for an hour or two 3 
 then add water, and when the solution is clear, pour it off, and pre- 
 cipitate it by fixed alkali — 131 grains of this precipitate, well Avash- 
 ed and dried, are equiA^alent to 100 of tin in its reguline state, if the 
 precipitate consist of pure tin 3 but if it contain copper or iron, it must 
 be calcined in a red heat for an hour, and then digested in nitrous 
 acid, which a\ ill take up the copper 3 and afterwards in marine acid, 
 which will separate the iron. 
 
 Lead Ores, — As most of the lead ores contain either sulphur or 
 arsenic, they require to be well roasted. Take a quintal of roasted 
 ore, with the same quantity of calcined borax, half a quintal of fine 
 powdered glass, a quarter of a quintal of pitch, and as much clean 
 iron filings. Line the crucible with wetted charcoal dust, and put 
 
APPENDIX. 
 
 759 
 
 the mixture into the crucible, and place it before the bellows of a 
 forge-fire. When it is red hot, raise the fire for 15 or 20 minutes, 
 then withdraw the crucible, and break it when cold. 
 
 In the humid way , — Dissolve the ore by boiling it in dilute nitrous 
 acid 5 the sulphur, insoluble stony parts, and calx of irgn will remain. 
 The iron may be separated by digestion, in the marine acid, and the 
 sulphur by digestion, in caustic fixed alkali. The nitrous solution 
 contains the lead and silver, which should be precipitated by the 
 mineral fixed alkali, and the precipitate well washed in cold water, 
 dried, and weighed. Digest it in caustic volatile alkali, which will 
 take up the calx of silver, the residuum being again dried and 
 weighed, gives the proportion of the calx of lead, 132 grains of 
 which are equal to 100 of lead in its metallic state. The differ- 
 ence of weight of the precipitate before and after the application 
 of the volatile alkali, gives the quantity of silver, 129 grains of which 
 are equal to 100 of silver in its metallic state. 
 
 Copper Ores . — Take an exact troy ounce of the ore, previously pul- 
 verized, and calcine it well j stir it all the time with an iron rod, 
 without removing it from the crucible ; after the calcination add an 
 equal quantity of borax, half the quantity of fusible glass, one-fourth 
 the quantity of pitch, and a little charcoal-dust 5 rub the inner sur- 
 face of the crucible, w'ith a paste composed of charcoal-dust, a little 
 fine powdered clay and water. Cover the mass with common salt, 
 and put a lid on the crucible, which is to be placed in a furnace : the 
 fire is to be raised gradually, till itbuins briskly, and the crucible con- 
 tinued in it for half an hour, stirring the metal frequently with an 
 iron rod, and \vhen the scoria which adheres to the rod appears 
 clear, then the crucible must be taken out, and suffered to cool 5 after 
 which it must be broken, and the regulus separated and weighed 5 
 this is called black copper, to refine which, equal parts of common 
 salt and nitre are to be well mixed together. The black copper is 
 brought into fusion, and a tea-spoonful of the flux is thrown upon 
 it, which is repeated three or four times, when the metal is poured 
 into an ingot mould, and the button is found to be fine copper. 
 
 In the humid way . — Make a solution of vitreous copper ore, in 
 5 times its weight of concentrated vitriolic acid, and boil it to dry- 
 ness j add as much water as will dissolve the vitriol thus formed 5 
 to this solution add a clean bar of iron which will precipitate the 
 whole of the copper in its metallic form. If the solution be conta- 
 minated with iron, the copper must be re-dissolved in the same man- 
 ner, and precipitated again. The sulphur may be separated by fil- 
 tration. 
 
 Bismuth Ores . — If the ore be mineralized by sulphur, or sulphur 
 and iron, a previous roasting will be necessary. The strong ores re- 
 quire no roasting, but only to be reduced to a fine powder. Take 
 the assay weight and mix it with half the quantity of calcined bo- 
 rax, and the same of pounded glass ; line the cimcible with charcoal •, 
 melt it as quickly as possible j and when well done, take out the cru- 
 
APPENDIX. 
 
 760 
 
 cible, and let it] cool gradually. The regulus will be found at the 
 bottom. 
 
 In the Humid way. — Bismuth is easily soluble in nitrous acid or 
 aqua-regia. Its solution is colourless, and is precipitable by the ad- 
 dition of pure, water j 118 grains of the precipitate from nitrous acid 
 well washed and dried, are equal to 100 of bismuth in its metallic 
 form. 
 
 Antimonial Ores. — Take a common crucible, bore a number of 
 email holes in the bottom, and place it in another crucible a size 
 smaller, luting them well together, then put the proper quantity of 
 ore in small lumps into the upper crucible, and lute thereon a cover ; 
 place these vessels on a hearth, and surround them with stones about 
 six inches distant from them j the intermediate space must be filled 
 xvith ashes, so that the undermost crucible may be covered with them ; 
 but upon the upper charcoal must be laid, and the whole made red 
 hot l)y the assistance of hand-bellow’S. The antimony being of easy 
 fusion is separated, and runs through the holes of the upper vessel 
 into the inferior one, where it is collected. 
 
 Humid Assay of Arseniated Dissolve the ore in aqua- 
 
 regia, both the regulus and arsenic remain in the solution, the sul- 
 phur is separated by filtration. If the solution be boiled with twice 
 its weight of strong nitrous acid, the regulus of antimony will be 
 precipitated, and the arsenic converted into an acid, which may be 
 obtained by evaporation to dryness. 
 
 Manganese Ore. — The regulus is obtained by mixing the calx or 
 ore of manganese with pitch, making it into a ball, and putting it into 
 a crucible, lined with powdered charcoal, 1-lOth of an inch on the 
 sides, and 5 of an inch at bottom, then filling the empty space with 
 charcoal dust, covering the crucible with another inverted and luted 
 on, and exposing it to the strongest heat of a forge for an hour or 
 more. 
 
 In the Humid Way. — The ores should be first well roasted to de- 
 phlogisticate the calx of manganese and iron, if any, and then treated 
 with nitrous acid to dissolve the earths. The residuum should now 
 be treated with nitrous acid aud sugar, by which means a colourless 
 solution of manganese will be obtained, and likewise of the iron, if 
 any. Precipitate with the Prussian alkali, and digest the precipitate 
 in pure water ; the prussiate of manganese will be dissolved, whilst 
 the prussiate of iron will remain undissolved. 
 
 Arsenical Ores. — This assay is made by sublimation in close ves- 
 sels. Beat the ore into small pieces, and put them into a matrass, 
 which place in a sand-pot, w ith a proper degree of heat ; the arsenic 
 sublimes in this operation, and adheres to the upper part of the ves- 
 sel ; when it must be carefully collected with a view to ascertain its 
 weight. Sometimes a single sublimation will not be sufficient, for 
 the arsenic in many cases will melt with the ore, and prevent its 
 total volatilization j in which case it is better to perform the first 
 sublimation with a moderate heat, and afterwards bruise the re- 
 mainder again, and expose it to a stronger heat. 
 
APPENDIX. 
 
 761 
 
 In the Humid rFat/.— -Digest the ore in marine acid, adding the 
 nitrous by degrees to help the solution. The sulphur will be found on 
 the filter j the arsenic will remain in the solution, and may be preci- 
 pitated in its metallic form by zinc, adding spirit of wine to the so- 
 lution. 
 
 Nickel Ore. — The ores must be well roasted to expel the sulphur 
 and arsenic 3 the greener the calx proves during this torrefaction, 
 the more it abounds in the nickel 3 but the redder it is, the more 
 iron it contains. The proper quantity of this roasted ore is fused in 
 an open crucible, with twice or thrice its weight of black flux, and 
 the whole covered with common salt. By exposing the crucible to 
 the strongest heat of a forge-fire, and making the fusion complete, 
 a regulus will be produced. This regulus is not pure, but contains a 
 portion of arsenic, cobalt, and iron. Of the first it may be deprived 
 by a fresh calcination, with the addition of powdered charcoal 5 and 
 of the second by scorification 3 but it is with difficulty that it is en- 
 tirely freed from the iron. 
 
 In the Humid Way. — By solution in nitrous acid, it is freed from 
 its sulphur ; and by adding water to the solution, bismuth, if any, 
 may be precipitated : as may silver, if contained in it, by the marine 
 acid ; and copper, when any, by iron. 
 
 To separate cobalt from nickel, when the cobalt is in considerable 
 quantity, drop a saturated solution of the roasted ore in nitrous acid 
 into liquid volatile alkali 3 the cobaltic part is instantly re-dissolved 
 and assumes a garnet colour 3 when filtered, a grey powder remains 
 on the filter, which is the nickel. The cobalt may be precipitated 
 from the volatile alkali by any acid. 
 
 Cobalt Ores. — Free them as much as possible from earthy matters 
 by well washing, and from sulphur and arsenic by roasting. The 
 ore thus prepared is to be mixed with three parts of black flux, and a 
 little decrepitated sea- salt : put the mixture in a lined crucible, cover 
 it, and place it in a forge-fire, or in a hot furnace, for this ore is very 
 difficult of fusion. 
 
 When well fused, a metallic regulus will be found at the bottom, 
 covered with a scoria of a deep blue colour : as almost all cobalt 
 ores contain bismuth, this is reduced by the same operation as the 
 regulus of cobalt ; but as they are incapable of chemically uniting 
 together, they are always found distinct from each other in the cru- 
 cible. The regulus of bismuth having a greater specific gravity, is 
 always at the bottom, and may be separated by a blow with a hammer. 
 
 In the Humid Way. — Make a solution of the ore in nitrous acid, 
 or aqua-regia, and evaporate to dryness 3 the residuum, treated with 
 the acetous acid will yield to it the cobaltic part ; the arsenic should 
 be first precipitated by the addition of water. 
 
 Mercurial Ores. — The calciform ores of mercury are easily reduced 
 without any addition. A quintal of the ore is put into a retort, and 
 a receiver luted on, containing some water 3 the retort is placed in a 
 sand-bath, and a sufficient degree of heat given it, to force over the 
 mercury which is condensed in the water of the receiver. 
 
APPENDIX. 
 
 762 
 
 Sulphurated Mercurial Ores . — ^Tlie sulphureous ores are assayed 
 by distillation in the manner above, only these ores require an equal 
 weight of clean iron-filings to be mixed with them, to disengage the 
 sulphur, while the heat volatilizes the mercury, and forces it into the 
 receiver. T!»ese ores should likewise be tried for cinnabar, to know 
 whether it will answer the purpose of extracting it from them : for 
 this a determinate quantity of the ore is finely powdered and put into 
 a glass vessel, which is exposed to a gentle heat at first, and gradually 
 increased till nothing more is sublimed. By the quantity thus acquired 
 a judgment may be formed whether the process will answer. Some- 
 times this cinnabar is not of so lively a colour as that which is used 
 in trade ; in this case it may be refined by a second sublimation, and 
 if it be still of too dark a colour, it may be brightened by the addi- 
 tion of a quantity of mercury, and subliming it again. 
 
 Humid Assay of Ci«naf;ar.— The stony matrix should be dissolved 
 in nitrous acid, and the cinnabar, being disengaged, should be boiled 
 in 8 or 10 times its weight of aqua regia, composed of 3 parts nitrous, 
 and 1 of marine acid. The mercury may be precipitated in its run- 
 ning form by zinc. 
 
 Silver Ores . — Take the assay quantity of the ore finely powdered, 
 and roast it well in a proper degree of heat, frequently stirring it 
 with an iron rod j then add to it about double the quantity of gra- 
 nulated lead, put it in a covered crucible, and place it in a furnace j 
 raise the fire gently at first, and continue to increase it gradually, 
 till the metal begins to work j if it should appear too thick, make it 
 thinner by the addition of a little more lead j if the metal should 
 boil too rapidly, the fire should be diminished. The surface will be 
 covered by degrees with a mass of scoria, at which time the metal 
 should be carefully stirred with an iron hook heated, 'especially to- 
 wards the border, lest any of the ore should remain undissolved j 
 and if what is adherent to the hook when raised from the crucible, 
 melts quickly again, and the extremity of the hook, after it is grown 
 cold, is covered with a thin, shining, smooth crust, the scorification is 
 perfect j but, on the contrary, if while stirring it, any considerable 
 clamminess is perceived in the scoria, and when it adheres to the 
 hook, though red hot, and appears unequally tinged, and seems dusty 
 or rough, with grains interspersed here and there, the scorification 
 is incomplete ; in consequence of which the fire should be increased 
 a little, and what adheres to the hook should be gently beaten off, 
 and returned with a small ladle into the crucible again. When the 
 scorification is perfect, the metal should be poured into a cone, pre- 
 viously rubbed with a little tallow, and when it becomes cold, the 
 scoria may be separated by a few strokes of a hammer. The button 
 is the produce of the assay. 
 
 By Take the assay quantity of ore, roast and grind 
 
 it with an equal portion of litharge, divide it into 2 or 3 parts, and 
 wrap each up in a small piece of paper 3 put a cupel previously sea- 
 soned under a muffle, with about 6 times the quantity of lead upon it. 
 AVhen the lead begins to work, carefully put one of the papers upon 
 
APPENDIX* 
 
 763 
 
 it, and after this is absorbed, put on a second, and so on till the whole 
 quantity is introduced^ then raise the fire, and as the scoria is formed, 
 it will be taken up by the cupel, and at last the silver will remain 
 alone. This will be the produce of the assay, unless the lead con- 
 tains a small portion of silver, which may be discovered by putting 
 an equal quantity of the same lead on another cupel, and working it 
 off at the same time ; if any silver be produced it must be deducted 
 from the assay. This is called the witness. 
 
 In the humid way . — Boil vitreous silver ore in dilute nitrous acid, 
 using about 25 times its weight, until the sulphur is quite exhausted. 
 The silver may be precipitated from the solution by marine acid, or 
 common salt ; 100 grains of this precipitate contain 75 of real silver 
 if it contain any gold it will remain undissolved. Fixed alkalies pre- 
 cipitate the earthy matters, and the Prussian alkali will show if any 
 other metal be contained in the solution. 
 
 To Assay the value of Silver , — The general method of examining 
 the purity of silver is by mixing it with a quantity of lead propor- 
 tionate to the supposed portion of alloy : by testing this mixture, 
 and afterwards weighing the remaining button of silver. This is the 
 same process as refining silver by cupellation. 
 
 It is supposed that the mass of silver to be examined, consists of 
 12 equal parts, called penny-weights j so that if an ingot weighs an 
 ounce, each of the parts will be l- 12 th of an ounce. Hence, if 
 the mass of silver be pure, it is called silver of 12 penny-weights 5 
 if it contain 1 - 1 2 th of its weight of alloy, it is called silver of 11 
 penny-weights : if 2 - 12 ths of its weight be alloy, it is called silver 
 of 10 penny-weights ; which parts of pure silver are called 5 penny- 
 weights. It must be observed here, that assayers give the name 
 penny-weight, to a w'eight equal to 24 real grains, which must not 
 be confounded with their ideal w'eights. The assayers’ grains a/e 
 called fine grains. An ingot of fine silver, or silver of 12 penny- 
 we’ghts, contains, then, 288 fine grains 3 if this ingot contain 1 -288th 
 of alloy, it is said to be silver of 11 penny-weights and 23 grains ; 
 if it contain 4-288ths of alloy, it is said to be 1 1 penny-weights, 20 
 grains, &c. Now a certain real weight must be taken to represent 
 the assay- weights : for instance, 36 real grains represent 12 fine 
 penny- weights ; this is subdivided into a sufficient number of other 
 smaller weights, wdiich also represent fractions of fine penny-weights 
 and grains. Thus, 18 real grains represent 6 fine penny- weights ; 
 3 real grains represent 1 fine penny-weight, or 24 grains 3 a real 
 grain and a half represents 12 fine grains : l-32d of a real grain re- 
 presents a quarter of a fine grain, which is only 1 -752nd part of a 
 massof 12 penny-w'eights. 
 
 Double Assay of Silver , — It is customary to make a double assay. 
 The silver for the assay should be taken from opposite sides of the 
 ingot, and tried on a touch-stone. Assayers know pretty nearly the 
 value of silver merely by the look of the ingot, and still better by 
 the test of the touch-stone. The quantity of lead to be added is re- 
 
APPENDIX. 
 
 764 
 
 gulated by the portion of alloy, which being in general copper, will 
 be nearly as follows : 
 
 dvvts. grs. 
 
 Silver of dwts. 
 
 11 
 0 
 19 
 8 
 6 
 3 
 1 
 
 From 
 
 grs. 
 
 6 
 
 12 
 
 18 
 
 6 
 
 18 
 
 0 
 
 12 
 
 to 
 
 0 
 
 12 
 
 0 
 
 12 
 
 18 
 
 Requires from 
 5 to 6 
 8— 9 
 
 12 — 13 
 
 13 — 14 
 
 14 
 
 .SP 
 
 "S 
 
 lo — J 4 / iS ^ 
 
 14—15 I*"- 
 0 — 16 1 I 
 0 — 20JS 
 
 The cupel must be heated red hot for half an hour before any me- 
 tal is put upon it, by which all moisture is expelled. When the cupel 
 is almost white by heat, the lead is put into it, and the fire increased 
 till the lead becomes red hot, smoking, and agitated by a motion of 
 all its parts, called its circulation. Then the silver is to be put on 
 the cupel, and the fire continued till the silver has entered the lead j 
 and when the mass circulates well, the heat must be diminished by 
 closing more or less the door of the assay furnace. The heat should 
 be so regulated, that the metal on its surface may appear convex and 
 ardent, while the cupel is less red j that the smoke shall rise to the 
 roof of the mufile ; that undulations shall be made in all directions ; 
 and that the middle of the metal shall appear smooth, with a small 
 circle of litharge, which is continually imbibed by the cupel. By 
 this treatment, the lead and alloy will entirely be absorbed by the cupel, 
 and the silver become bright and shining, when it is said to lighten j 
 after which, if the operation has been well performed, the silver will 
 be covered with rainbow colours, which quickly undulate and cross 
 each other, and then the button becomes fixed and solid. 
 
 The diminution of weight shews the quantity of alloy. As all lead 
 contains a small portion of silver, an equal weight with that used in 
 the assay, is tested off, and the product deducted from the assay 
 weight. This portion is called the witness. 
 
 To Assay Plated Metals , — Take a determinate quantity of the 
 plated metal j put it into an earthen vessel, with a sufficient quan- 
 tity of the above menstruum, and place it in a gentle heat. When 
 the silver is stripped, it must be collected with common salt ; the 
 calx must be tested with lead, and the estimate made according to 
 the product of silver. 
 
 Ores and Earths containing Gold. — No, 1 .—That which is now 
 most generally used is by amalgamation, the proper quantity is taken 
 and reduced to a powder ; about 1-1 0th of its weight of pure quick- 
 silver is added, and the whole triturated in an iron mortar. The at- 
 traction subsisting between the gold and quicksilver, quickly unites 
 them in the form of an amalgam, which is pressed through sharaois 
 leather ; the gold is easily separated from this amalgam, by exposure 
 to a proper degree of heat, which evaporates the quicksilver, and 
 leaves the gold. This evaporation should be made with luted vessels. 
 
 This is the foundation of all the operations by which gold is ob- 
 tained from the rich mines of Peru, in Spanish America. 
 
APPENDIX. 
 
 765 
 
 No. 2. — ^Take a quantity of the gold-sand, and heat it red-hot, 
 quench it in water j repeat this two or three times, and the colour of 
 the sand will become a reddish brown. Then mix it with twice its 
 weight of litharge, and revive the litharge into lead, by adding a 
 small portion of charcoal-dust, and exposing it to a proper degree of 
 heat j when the lead revives, it separates the gold from the sand j 
 and the freeing of the gold from the lead must be afterwards per- 
 formed by cupellation. 
 
 No. 3. — ’Bergman assayed metallic ores containing gold, by mixing 
 two parts of the ore, well pounded and washed, with 1^ of litharge, 
 and 3 of glass ; covering the whole with common salt, and melting it 
 in a smith’s forge, in a covered crucible 3 he then opened the crucible, 
 put a nail into it, and continued to do so, till the iron was no longer 
 attacked. The lead w^as thus precipitated which contained the gold, 
 and was afterw’ards separated by cupellation. 
 
 Humid Assay of Gold mixed with Martial Pyrites. — Dissolve the 
 ore in twelve times its weight of dilute nitrous acid, gradually added j 
 place it in a proper degree of heat j this takes up the soluble parts, 
 and leaves the gold untouched, with the insoluble matrix, from which 
 it may be separated by aqua regia. The gold may be again separated 
 from the aqua regia by pouring ether upon it 3 the ether takes up the 
 gold, and by being burnt off leaves it in its metallic state. The solu- 
 tion may contain iron, copper, manganese, calcareous earth, or argil 3 
 if it be evaporated to dryness, and the residuum heated to redness 
 for half an hour, volatile alkali will extract the copper 3 dephlogisti- 
 cated nitrous acid, the earths^ the acetous acid, the manganese 3 and 
 the marine acid, the calx of iron. The sulphur floats on the first 
 solution, from which it should be separated by filtration. 
 
 PARTING. 
 
 By this process gold and silver are separated from each other. 
 These two metals equally resisting the action of fire and lead, must 
 therefore be separated by other means. This is effected by different 
 menstrua. Nitrous acid, marine acid and sulphur, which cannot attack 
 gold, operate upon silver 3 and these are the principal agents em- 
 ployed in this process. 
 
 Parting by nitrous acid is most convenient, consequently most 
 used, — indeed, it is the only one employed by goldsmiths. This is 
 called simply parting. 
 
 That made by the marine acid is by cementation, and is called 
 centrated parting ; and parting by sulphur is made by fusion, and 
 called Dry Parting. 
 
 Parting by Aqua^Fortis. This process cannot succeed unless we 
 attend to some essential circumstances : 1st. The gold and silver 
 must be in a proper portion, viz. the silver ought to be three parts to 
 one of gold 3 though a mass containing two parts of silver to one of 
 
APPENDIX. , 
 
 766 
 
 gold may be parted. To judge of the quality of the metal to be 
 parted, assayers make a comparison upon a touch-stone, between it 
 and certain needles composed of gold and silver, in graduated pro- 
 portions, and properly marked ,• which are called Proof Needles. 
 If this trial shews that the silver is not to the gold as three to one, 
 the mass is improper for the operation, unless more silver be added ; 
 and 2dly, that the parting may be exact, the aqua-fortis must be vecy 
 pure, especially free from any mixture of the vitriolic or marine acid. 
 For if this were not attended to, a quantity of silver proportionable 
 to these two foreign acids would be separated during the solution ; 
 and this quantity of sulphate of silver would remain mingled with 
 the gold, which consequently would not be entirely purified by the 
 operation, 
 
 - The gold and silver to be parted ought previously to be granulated, 
 by melting it in a crucible, and pouring it into a vessel of water, 
 giving the water at the same time a rapid circular motion, by quickly 
 stirring it round with a stick. The vessels generally used in this 
 operation are called parting glasses, which ought to be very well 
 annealed, and chosen free from flaws ; as one of the chief inconve- 
 niences attending the operation is, that the glasses are apt to crack by 
 exposure to cold, or even when touched by the hand. Some operators 
 secure the bottom of che glasses by a coating composed of a mixture 
 of new-slaked lime, with beer and whites of eggs spread on a cloth, 
 and wrapped round the glasses at the bottom ; over which they apply 
 a composition of clay and hair. The parting glasses should be 
 placed in vessels containing water supported by trivets, with a fire 
 under them ; because if a glass should break, the contents are caught 
 in the vessel of water. If the heat communicated to the water be 
 too great, it may be properly regulated by pouring cold water gradually 
 and carefully down the side of the vessel into a parting glass 15 
 inches high, and 10 or 12 inches wide at the bottom ; placed in a 
 copper pan 12 inches wide at bottom, 15 inches wide at top, and 10 
 inches high 3 there is usually put about 80 oz. of metal, with twice 
 as much of aqua-fortis. 
 
 The aqua-fortis ought to be so strong as to act sensibly on silver 
 when cold, but not so strong as to act violently. Little heat should 
 be applied at first, as the liquor is apt to swell and rise over the 
 vessel 5 but when the acid is nearly saturated, the heat may safely be 
 increased. When the solution ceases, which is known by the effer- 
 vescence discontinuing, the liquor is to be poured off, if any grains 
 appear entire, more aqua-fortis must be added, till the silver is all 
 dissolved. If the operation has been performed slowly, the remaining 
 gold will have the form of distinct masses. The gold appears black 
 after parting ; its parts have no adhesion together, because the silver 
 dissolved from it has left many interstices. To give them more soli- 
 dity, and improve their colour, they are put into a test under a muQle, 
 and made red hot, after which they contract and become more solid, 
 and the gold resumes its colour and lustre. It is then called Grain 
 Gold. If the operation has been performed hastily, the gold will 
 
APPENDIX. 7^7 
 
 have the appearance of black mud or powder, which, after well 
 washing, must be melted. 
 
 The silver is usually recovered by precipitating it from the aqua- 
 fortis by means of pure copper. If the solution be perfectly satu- 
 rated, no precipitation can take place, till a few drops of aqua-fortis 
 are added to the liquor. The preeipitate of silver must be w'ell 
 washed with boiling water, and may be fused with nitre, or tested off 
 with lead. 
 
 Parting ly Cementation.’^^ cement is prepared, composed of 4 
 parts of bricks powdered and sifted 5 of one part of green vitriol 
 calcined till it becomes red j and of one part of common salt : this 
 is to be made into a firm paste with a little water. It is called the 
 Cement Royal. 
 
 The gold to be cemented is reduced into plates as thin as money. 
 At the bottom of the crucible or cementing pot, a stratum of cement, 
 of the thickness of a finger, is put, which is covered with plates of 
 gold ; and so the strata are placed alternately. The w’hole is covered 
 wdth a lid, which is luted with a mixture of clay and sand. This 
 pot must be placed in a furnace or oven, heated gradually till it 
 becomes red hot, in which it must be continued during 24 hours. The 
 heat must not melt the gold. The pot or crucible is then suffered to 
 cool ; and the gold carefully separated from the cement, and boiled 
 at different times in a large quantity of pure water. It is then assayed 
 upon a touch-stone, or otherwise 5 and if it be not sufficiently pure, 
 it is cemented a second time. In this process the vitriolic acid of the 
 bricks, and of the calcined vitriol, decomposes the common salt during 
 the cementation, by uniting to its alkaline base, w'hile the marine acid 
 becomes concentrated by the heat, and dissolves the silver alloyed 
 with the gold. This is a very troublesome process, though it suc- 
 ceeds when the portion of silver is so small that it would be defended 
 from the action of aqua-fortis by the super-abundant gold j but is 
 little used, except to extract silver, or base metals, from the surface 
 of gold, and thus giving to an alloyed metal, the colour and appear- 
 ance of pure gold. 
 
 Dry Parting. — This process is performed by sulphur, which will 
 easily unite with silver, but does not attack gold. As this dry 
 parting is even troublesome as well as expensive, it ought not to be 
 undertaken but on a considerable quantity of silver alloyed with gold. 
 The general procedure is as follows. — The metal must be granulated^ 
 from T8 to 1*5 of it (according as it is richer or poorer in the gold.) 
 is reserved, and the rest well mingled with an eighth of powdered 
 sulphur 5 and put into a crucible, keeping a gentle fire, that the sil- 
 ver, before melting, may be thoroughly penetrated by the sulphur ; 
 if the fire be hastily urged, the sulphur will be dissipated. If to 
 sulphurated silver infusion, pure silver be added, the latter falls to 
 the bottom, and forms there a distinct fluid, not miscible with the 
 other. The particles of gold having no affinity with the sulphurated 
 silver, join themselves to the pure silver wherever they come in con- 
 tact, and are thus transferred from the former into the latter, more or 
 
APPENDIX. 
 
 7C8 
 
 less perfectly, according as the pure silver was more or less thorough- 
 ly diffused through the mixture. It is for this use that a part of the 
 granulated silver was reserved. The sulphurated mass being brought 
 into fusion, and kept melting for nearly an hour in a covered crucible, 
 one third of the reserved grains is thrown in, which, when melted, 
 the whole is well stirred, that the fresh silver may be distributed 
 through the mixed to collect the gold from it ; this is performed with 
 a wooden rod. This is repeated till the whole reserved metal be in- 
 troduced. The sulphurated silver appears, in fusion, of a dark brown 
 colour 3 after it has been kept in fusion for a certain time, a part of 
 the sulphur having escaped from the top, the surface becomes white, 
 and some bright drops of silver, about the size of a pea, are perceived 
 on it. When this happens the fire must be immediately disconti- 
 nued, for otherwise more and more of the silver thus losing its sul- 
 phur, would subside and mingle with the part at the bottom, in which 
 the gold is collected. The w^hole is poured into an iron mortar greased 
 and duly heated. The gold diffused at first through the whole mass, 
 is now found collected in a part of it at the bottom, (amounting only 
 to about as much as was reserved unsulphurated from the mass) by a 
 chisel or hammer, or more perfectly by placing the whole mass with 
 its bottom upwards in a crucible, the sulphurated part quickly melts, 
 leaving, unmelted, that which contains the gold. The sulphurated 
 silver is assayed, by keeping a portion of it in fusion in an open cru- 
 cible, till the sulphur is dissipated, and then by dissolving it in aqua- 
 fortis. If it should still be found to contain gold, it must be sub- 
 jected to the same treatment as before. The gold thus collected may 
 be concentrated into a smaller part by repeating the whole process, 
 so that at last it may be parted by aqua-fortis without too much ex- 
 pense. 
 
 IRON AND STEEL; 
 
 Expeditious mode of reducing Iron Ore into Mallealle /ro72.— The 
 way of proceeding is by stamping, washing, &c. the calcine and ma- 
 terials, to separate the ore from extraneous matter j then fusing the 
 prepared ore in an open furnace, and instead of casting it, to suffer 
 it to remain at the bottom of the furnace till it becomes cold. 
 
 New Method of Shingling and Manufacturing Iron. — The ore 
 being fused in a reverberating furnace, is conveyed, whilst fluid, into 
 an air-furnace, where it is exposed to a strong heat, till a bluish 
 flame is observed on the surface ; it is then agitated on the surface, 
 till it loses its fusibility, and is collected into lumps called loops. 
 These loops are then put into another air-furnace, brought to a white 
 or welding heat, and then shingled into half-l looms or slabes. They 
 are again exposed to the air-furnace, and the half-blooms taken out 
 and forged into anconies, bars, half-Jiats, and rods for tvire 3 while 
 the slabes are passed, when of a welding heat, through the grooved 
 rollers. In this way of proceeding, it matters not whether the iron 
 is prepared from cold or hot-short metal, nor is there any occasion 
 
APPENDIX. 
 
 for the use of finery, charcoal, coke, chafery, or hollow fire 5 or any 
 blast by bellows j or otherwise : or the use of fluxes, in any part of 
 the process. 
 
 Approved Method of Welding /row.— This consists in the skilful 
 bundling of the iron to be welded j in the use of an extraordinary 
 large forge-hammer, in employing a balling-furnace, instead of a hol- 
 low fire or chafery ; and in passing the iron, reduced to a melting heat, 
 through grooved mill-rollers of different shapes and sizes, as required. 
 
 Common Hardening. — Iron, by being heated red hot, and plunged 
 into cold water, acquires a great degree of hardness. This proceeds 
 from the coldness of the water which contracts the particles of the 
 iron into less space. 
 
 Case- Hardening. -^Case-h'dvdenmg is a superficial conversion of 
 iron into steel by cementation. It is performed on small pieces of 
 iron, by enclosing them in an iron box, containing burnt leather, 
 bone-dust, or any other carbonic material, and exposing them for 
 some hours to a red heat. The surface of the iron thus becomes per- 
 fectly metallized. Iron thus treated is susceptible of the finest polish. 
 
 To convert Iron into Steel by Cementatiom — The iron is formed 
 into bars of a convenient size, and then placed in a cementing fur- 
 nace, with sufficient quantity of cement, which is composed of coals 
 of animal or vegetable substances, mixed with calcined bones, &c. The 
 following are very excellent cement : — 1st, one part of powdered 
 charcoal, and half a part of wood-ashes well mixed together 5 or, 
 2dly, two parts of charcoal, moderately powdered, one part of bones, 
 horn, hair, or skins of animals, burnt in close vessels to blackness 
 and powdered 5 and half a part of wood-ashes 5 mix them well to- 
 gether. The bars of iron to be converted into steel, are placed upon 
 a stratum of cement, and covered all over with the same ; and the 
 vessel which contains them, closely luted, must be exposed to a red 
 heat for 8 or 10 hours, when the iron will be converted into steel. 
 
 Steel is prepared from bar iron by fusion ; which consists of plung- 
 ing a bar into melted iron, and keeping it there for tome time, by 
 which process it is converted into good steel. 
 
 All iron which becomes harder by suddenly quenching in cold 
 water is called steel 5 and that steel w'hich in quenching acquires the 
 greatest degree of hardness in the lowest degree of heat, and retains 
 the greatest strength in and after induration, ought to be considered 
 as the best. 
 
 Improved process of hardening Steel. — Articles manufactured of steel 
 for the purposes of cutting, are, almost without an exception, hard- 
 
 • ened from the anvil j in other words, they are taken from the forger 
 
 • to the hardener without undergoing any intermediate process ; and 
 such is the accustomed routine, that the mischief arising has escaped 
 observation. The act of forging produces a strong scale or coating, 
 which is spread over the whole of the blade ; and to make the evil 
 still more formidable, this scale or coating is unequal in substance 
 varying in proportion to the degree of heat communicated to the 
 steel in forging j it is, partially, almost impenetrable to the action of 
 
APPENDIX. 
 
 770 
 
 water* when immersed for the purpose of hardening. HenCe it is 
 that different degrees of hardness prevail in nearly every razor ma- 
 nufactured : this is evidently a positive defect j and so long as it 
 continues to exist, great difference of temperature must exist like- 
 wise. Razor-blades not unfrequently exhibit the fact here stated in 
 a very striking manner ; what are termed clouds, or parts of unequal 
 polish, derive their origin from this cause 3 and clearly and distinctly, 
 or rather distinctly though not clearly, show how far this partial 
 coating has extended, and where the action of the water has been 
 yielded to, and where resisted. It certainly cannot be matter of asto- 
 nishment, that so few improvements have been made in the harden- 
 ing of steel, when the evil here complained of so universally obtains, 
 as almost to warrant the supposition that no attempt has ever been 
 made to remove it. The remedy, however, is easy and simple in the 
 extreme, and so evidently efficient in its application, that it cannot 
 but excite surprise, that, in the present highly improved state of our 
 manufactures, such a communication should be made as a discovery 
 entirely new. 
 
 Instead, therefore, of the customary mode of hardening the blade 
 from the anvil, let it be passed immediately from the hands of the 
 forger to the grinder ; a slight application of the stone will remove 
 the whole of the scale or coating, and the razor will then be properly 
 prepared to undergo the operation of hardening with advantage. It 
 will be easily ascertained, that steel in this state heats in the fire with 
 greater regularity, and that when immersed, the obstacles being re-> 
 moved to the immediate action of the water on the body of the steel, 
 the latter becomes equally hard from one extremity to the other. To 
 this may be added, that, as the lowest possible heat at which steel be- 
 comes hard is indubitably the best, the mode here recommended will 
 be found the only one by which the process of hardening can be 
 effected vvith a less portion of lire than is, or can be required in any 
 other way. These observations are decisive, and will, in all proba- 
 bility, tend to establish in general use what cannot but be regarded 
 as a very important improvement in the manufacturing of edged steel 
 instruments. 
 
 i^nglish cast Steel, — The finest kind of steel, called English cast 
 steel, is prepared by breaking to pieces blistered steel, and then melting 
 it in a crucible with a flux composed of carbonaceous and vitrifiable in- 
 gredients. The vitrifiable ingredient is used only inasmuch as a fusi- 
 ble body, which flows over the surface of the metal in the crucibles, 
 and prevents the access of the oxygen of the atmosphere. Broken glass 
 is sometimes used for this purpose'. 
 
 When thoroughly fused it is cast into ingots, which by gentle heat- 
 ing and careful hammering; are tilted into bars. By this process the' 
 steel becomes more highly carbonized in proportion to the quantity of 
 flux, and in consequence is more brittle and fusible than before. 
 Hence, it surpasses all other steel in uniformity of texture, hardness, 
 and closeness of grain, and is the material employed in all the finest' 
 articles of English cutlery. 
 
APPENDIX. 
 
 771 
 
 To make Edge-tools from cast Steel and Iron. — This method con- 
 sists in fixing a clean piece of wrought iron, brought to a welding 
 heat, in the centre of a mould, and then pouring in melted steel, so 
 as entirely to envelope the iron j and then forging the mass into the 
 shape required. 
 
 To colour Steel Blue. — The steel must be finely polished on its 
 surface, and then exposed to an uniform degree of heat. Ac- 
 cordingly, there are three ways of colouring : first, by a flame pro- 
 ducing no soot, as spirit of wine 5 secondly, by a hot plate of iron ; 
 and thirdly, by wood-ashes. As a very regular degree of hccft is 
 necessary, wood- ashes for fine work bears the preference. The work 
 must be covered over with them, and carefully watched ; when the 
 colour is sufficiently heightened, the work is perfect. Tliis colour is 
 occasioually taken off with a very dilute marine acid. 
 
 To distinguish Steel from Iron. — Tlie principal characters by which 
 steel may be distinguished from iron, are as follow : — 
 
 1. After being polished, steel appears of a whiter, light grey hue, 
 without the blue cast exhibited by iron. It also takes a higher polish. 
 
 2. The hardest steel when not annealed, appears granulated, but 
 dull, and without shining fibres. 
 
 3. When steeped in acids the harder the steel is, of a darker hue 
 is its surface. 
 
 4. Steel is not so much inclined to rust as iron. 
 
 5. In general, steel has a greater specific gravity. 
 
 6. By being hardened and wrought, it may be rendered much more 
 elastic than iron. 
 
 7. It is not attracted so strongly by the magnet as soft iron. It 
 likewise acquires magnetic properties more slowly, but retains them 
 longer j for which reason, steel is used in making needles for com- 
 passes, and artificial magnets. 
 
 8. Steel is ignited sooner, and fuses with less degree of heat, than 
 malleable iron, which can scarcely be made to fuse without the ad- 
 dition of powdered charcoal ; by which it is converted into steel> 
 and afterwards into crude iron. 
 
 9. Polished steel is sooner tinged by heat, and that with higher 
 Colours, than iron. 
 
 10. In a calcining heat, it suffers less loss by burning, than sUft 
 iron does in the same heat, and the same time. In calcination a light 
 blue flame hovers over the steel, either with or without a sulphure- 
 ous odour. 
 
 11. The scales of steel are harder and sharper than those of iron j 
 and consequently more fit for polishing with. 
 
 12. In a white heat, when exposed to the blast of the bellows 
 among the coals, it begins to sweat, wet, or melt, parti}’ with light- 
 coloured and bright, and partly with red sparkles, but less crackling 
 than those of iron. In a melting heat too, it consumes faster. 
 
 13. In the vitriolic, nitrous> and other acids, steel is violently at- 
 tacked, but is longer in dissolving than iron. After maceration, ac- 
 cording as it is softer or harder, it appears of a lighter, or darker grey 
 colour j while iron on the other hand is white. 
 
 3 D 2 
 
GLOSSARY, 
 
 Molopiie A hollov/ metallic ballj with a small orificev 
 
 to shew the power of steam. 
 
 Anneal To expose iron or other metals to the action 
 
 of fire, in order to reduce them to a greater 
 degree of tenacity. 
 
 Anvil A block or mass of iron, with a hardened 
 
 steel surface, on which smiths and other 
 artificers hammer and fashion their work. 
 
 Arhor, .... .i , The principal spindle or axis which commui- 
 
 nicates motion to the other parts of a ma- 
 chine. 
 
 Arm,,-, • . • The length of the sail of a windmill measured 
 
 from the axis. 
 
 Arms (Axle) The two ends of an axle-tree: projecting’ 
 
 supports in machinery. 
 
 Ash-hole A receptacle for the ashes which fall from the 
 
 hearth of a furnace. 
 
 Attraction of Cohesion. The attraction which holds the particles of 
 matter to each other. 
 
 of Gravitation, The force which causes all ponderous bodies 
 
 to fall towards the earth’s centre. 
 
 Augur The wimble or tool used in the boring of 
 
 woods. 
 
 Automaton,, A machine which, by an internal arrange^' 
 
 ment, seems to move of itself. 
 
 Axis The spindle or centre of any rotatory motion. 
 
 — — (f oscillation . . The shaft upon which any body vibrates. 
 
 in peritrochio. , , One of the six mechanical powers ; usually 
 
 called the wheel and axle. 
 
 i of rotation The shaft round v/hich any body revolves. 
 
 Backboards Boards attached to the rims of the water-' 
 
 wheel, to prevent the water running off 
 the floats into the interior of the wheel. 
 
 Backlash t,,, ,, The hobbling movement of a wheel not 
 fixed firm on its axis. 
 
 Back-vjater The water which impedes the motion of a 
 
 water-wheel during floods, or from other 
 causes. 
 
 Balance An instrument which, by the application of 
 
 the lever, exhibits the weights of bodies. 
 
APPENDIX. • 
 
 773 
 
 Batten The movable lath or bar of a loom which 
 
 serves to strike in or close, more or less, 
 the threads of a woof : a long narrow slip 
 of wood in carpentry. 
 
 Batter A machine used early in the process of the 
 
 cotton manufacture. 
 
 Bayonet A piece of wood or metal with two legs to 
 
 'disengage and re-engage machinery : vide 
 Mill-Geering. 
 
 Beats The strokes made by the pallets or fangs of 
 
 a spindle in clock or watch movements. 
 
 Beetle, , An implement for flattening the texture of 
 
 linen or w^oollen cloth : a heavy mallet. 
 
 Bevel-geer V/heels in which the teeth are set at angles 
 
 of various degrees from the radius. 
 
 Bitts Small tools used in boring. 
 
 Bloom A bar of iron to be passed through the rol- 
 
 lers of an iron -mill to be elongated into a 
 bar, rod, or hoop. 
 
 Blunging The act of mixing or kneading clay for the 
 
 potter’s use. 
 
 BoH'ins. Little circular pieces of wood on which the 
 
 thread of cotton, silk, &c. is wound. 
 
 Bolter A machine for sifting meal. 
 
 Bolting-cloth A cloth through which the sifted meal runs. 
 
 Brace A curved instrument of iron or wood for mov- 
 
 ing small boring tools called bitts. 
 
 Bracket A support fixed to a wall. 
 
 Brake A machine for separating the cuticle or outer 
 
 skin from the flax plant. 
 
 Brazing The soldering or joining two pieces of metal 
 
 by melting of brass between the pieces to 
 be joined. 
 
 Breast The first part of a revolver carding-engine.. 
 
 Breasting . , 4 . . • The circular sweep of masonry, &c. which sur- 
 
 rounds the shuttle side of a breast-wheel. 
 
 Breasi-plate A small piece of steel with holes to receive 
 
 the ends of a drill. 
 
 Breast^wheel., , A water-wheel on which w’ater is admitted 
 
 at or nearly level with the axis. 
 
 Buff-stick Apiece of wood covered with buff leather, 
 
 used for polishing. 
 
 Bullet To alter the wards of a lock in such manner 
 
 that they may be passable by more than 
 one key. 
 
 Bush A hole in the nave of a wheel. 
 
 Cceteris paribus Other things being equal. 
 
 Calibre The diameter of a hole. 
 
 Calk,, To force oakum, tow, or other material in 
 
774 
 
 APPENDIX. 
 
 the joints of vessels^ to make them steam, 
 air, or water-tight. 
 
 Camh r. .. An eccentric. 
 
 Capstan,, A vertical post resting on a pivot and turned 
 
 by powerful arms or levers to raise heavy 
 weights by crane work ; a windlass. 
 
 Carton Charcoal. 
 
 Card Piece of leather containing numerous iron- 
 
 wire teeth, forming a species of comb‘d 
 vide Cotton Manufacture. 
 
 Case-harden The process of converting the surface of iron 
 
 into steel. 
 
 Casting.,,.,,,,,,,., The act of forming metal or other matter 
 into any required shape, by pouring it into 
 moulds while in a fluid state. 
 
 Catch, Various contrivances in mechanics, to act oq 
 
 the principle of a latch. 
 
 Cement. .. A composition for joining hard bodies. 
 
 Centre- bit A boring tool in carpentry. 
 
 Centrifugal Flying from the centre. 
 
 Centripetal Flying to the centre. 
 
 Chafery.,, A kind of forge in the iron manufacture, 
 
 wiiere the metal is exposed to a welding 
 heat. 
 
 Chaliometer An instrument to measure heat. 
 
 Chamfer A groove to receive the tenon in carpentry. 
 
 Checks A term generally applied to those pieces of 
 
 timber in machinery, which are double, 
 and correspond with each other. 
 
 Chord Perpendicular let fall from any radius of a 
 
 circle. 
 
 Chuck.,, That part of a lath which revolves with the 
 
 arbor : to this is affixed the article to be 
 turned. 
 
 Circumference The measure round any circle. 
 
 Clack A bell so contrived that it shall ring when 
 
 more corn is required to be put in the mill. 
 
 Clamp A pile of unburnt bricks raised for burning. 
 
 Clip An arrangement to impede velocity by fric-^ 
 
 tion. 
 
 Clutch Vide Bayonet. 
 
 Cockling To entangle. 
 
 Cocoon A small ball of silk spun by a silk-v;orm. 
 
 Cog . This word, correctly speaking, implies teeth 
 
 formed of a dilferent material to the body 
 of the wheel ; but is generally used to 
 express all kinds of toothed wheels. 
 
 Concentric Having the same centre. 
 
 Conspiring forces. ,, ,, Various forces combined into one. 
 
 Constant forces Force without interruption. 
 
APPENDIX. 
 
 775 
 
 Contractile farces. .... Forces which decrease. 
 
 Core The internal mould which forms a hollow in 
 
 foundry : as the hollow of a tub or pipe. 
 
 Countersink . • To take off the edge round a hole to let in a 
 
 screw-head^ that it may be even with the 
 surface. 
 
 Couplings To connect two shafts or spindles longitudi- 
 
 nally. 
 
 Coupling-box,,^,,,,, A strong piece of hollow iron to connect 
 shafting and throw machinery in and out 
 of geer. 
 
 Crank,,, A bent part of a shaft, by means of which 
 
 a rectilinear motion is gained. 
 
 Crow-har A strong bar of iron used as a temporary 
 
 lever. 
 
 Crown-wheel Awheel which has teeth at right angles to 
 
 its radii. 
 
 Cycloid A geometric curve. 
 
 Cylinder A long round body ; a roller. 
 
 Dam The bank or w all which pens back the water 
 
 in a mill-head. 
 
 Data Facts from which we may deduce results. 
 
 Decimetre. To measure by tenths. 
 
 Dent. ,, The wire staple which constitutes the tooth 
 
 of a card. 
 
 Devil A machine for dividing rags or cotton in the 
 
 first process of the manufacture of paper 
 or cotton. 
 
 Diameter The line which passes through the centre of 
 
 a circle. 
 
 Die Pieces of steel for cutting screws, having the 
 
 threads countersunk on them : a stamp. 
 
 Doffer That part of a carding machine w'hich tak s 
 
 the cotton from the cylinder. 
 
 Doffing-plate The plate which receives the cotton from the 
 doffer. 
 
 Dog A piece in small machinei^ w^hich acts as 
 
 a pall. 
 
 Draw-plate A steel plate, having a gradation of conical 
 
 holes, through which metals are drawn to 
 be reduced and elongated. 
 
 Drench To wet or inundate. 
 
 Drill-bow. A small bow moved by hand to impart mo- 
 
 tion to a drill. 
 
 Drum A hollow cylinder. 
 
 Ductile Malleable and soft. 
 
 Dicentric Deviating from the centre ; as cambs, at- 
 
 tached to the rim or circumference of a 
 shaft for lifting forge hammers, stampers^ 
 &c. 
 
APPENDIX. 
 
 776 
 
 effective-head The real head, or that which can be applied 
 
 to practice. 
 
 effluent Flowing from j running out. 
 
 effliuv The act of flowing out. 
 
 epicycloid The curve described in the air by a point on 
 
 the circumference of a circle, when this 
 circle rolls on another circle as its base. 
 
 Equilihrium That peculiar state of rest in which a body 
 
 is maintained by the force of gravitation, 
 when the quantity of matter in it is ex- 
 actly equal on each side of the bar or point 
 on which it is supported. 
 
 Escapement • The part of a clock or watch movement 
 
 whidi receives the force of the spring or 
 weight, to give motion to the pendulum or 
 oalance. 
 
 Face of the tooth The curved part of a tooth which imparts 
 
 impulse to another wheel. 
 
 Faggot Pieces of iron bound together for re-manu- 
 
 facture. 
 
 Fan Small vanes or sails to receive the impulse of 
 
 the wind, and, by a connexion with ma- 
 chinery, to keep the large sails cf a smock 
 wind-mill always in the direction of the 
 wind : an instrument to winnow corn 3 also 
 to decrease speed by its action on the air. 
 
 Female-’Screw The spiral threaded cavity in which a screw 
 
 operates. 
 
 File A tool used by smiths for the abrasion of 
 
 metals 3 denominated, according to its 
 fineness, rough, bastard, or smooth. 
 
 First-mover Power, either natural or artificial. 
 
 Flanch An edge or projection for the better connexion 
 
 of piping or castings of any description. 
 
 Flarik of the tooth The straight part of a tooth which receives 
 
 impulse from another wheel. 
 
 Float, , . The board which receives* the impulse of 
 
 the w ater either in breast or undershot- 
 wdieels. 
 
 Floodgate > A strong framing of timber to pen back or 
 
 let out water. 
 
 Flux.,,, Ingredients put into a smelting furnace to 
 
 fuse the ore of metals. 
 
 Fly-wheel A heavy wheel to maintain equable motion. 
 
 Foot-brake A machine used in the flax manufacture. 
 
 Forge A manufactory in which metals are made 
 
 malleable 3 a furnace. 
 
 To form by the hammer. 
 
 Friction.,, ,, Iiiei'puiUty of surface 3 act of rubbing together. 
 
APPENDIX. 
 
 777 
 
 Frisket Au iron frarae used in printing to keep the 
 
 ; sheet of paper on the tyrapan, and to pre- 
 
 vent the margin from being blacked. 
 
 Fulcrum The point or bar on which a lever rests. 
 
 Geering Part of mill-work. 
 
 Gibbet That part of a crane which sustains the 
 
 weight of goods. 
 
 Gig-mill A mill in which the nap of woollen cloth is 
 
 raised by the application of teasels. 
 
 Girder The largest timber in a floor. 
 
 Girt Fide Gripe. 
 
 Gravity Tendency towards the centre of the earth ; 
 
 weight 
 
 Gripe., A pliable lever which can be pressed against 
 
 a wheel to retard or stop its motion by 
 friction. 
 
 Governor A pair of heav^' balls connected with ma? 
 
 chinery to regulate the speed on the prin- 
 ciple of central force. 
 
 Gudgeon The centres or pivots of a water-wheel. 
 
 Half-stuff. This term, in general, implies any thing 
 
 half-formed in the process of the manu- 
 facture. 
 
 Heald or Heddle Fide Heddle. 
 
 Heckle A metal comb for the manufacture of flax. 
 
 Heddle That portion of a loom which imparts mo- 
 
 tion to the warp of a web during the pro- 
 cess of manufacture. 
 
 Helve The shaft of a forge or tilt-hammer. 
 
 Hopper A funnel in which grain is deposited, whence 
 
 it runs between the stones of a flour-mill. 
 
 Horology The art of constructing machines for mea- 
 
 suring time. 
 
 Hydraulics,, ,,,m ,, The science which treats of the motion of 
 fluids, of the resistance which they oppose 
 to moving bodies, and of the various ma- 
 chines in which fluids are the principal 
 agent. 
 
 Hydrodynamics, The science which embraces the phenomena 
 
 exhibited by wmter and other fluids, whe- 
 ther they be at rest or in motion : it is 
 generally divided into two heads, hydro- 
 statics and hydraulics. 
 
 Hydrostatics.,,,,..,, The science which considers the pressure, 
 equilibrium, and cohesion of fluids. 
 
 Impact Transmission of force. 
 
 Impinge. To dash against. 
 
 Inertia . ,,,,,,,,,,,, That tendency which every piece of matter 
 
778 
 
 iJwFPENDIX. 
 
 has, when at rest, to remain at rest; and 
 when in motion, to continue that motion. 
 
 In Vacuo Empty space, void. 
 
 Isochronal Of equal duration. 
 
 Isochronous The vibrations of a pendulum. 
 
 Jenney A machine used in the process of the cotton 
 
 manufacture. 
 
 Jib Vide Gibbet. 
 
 Kiln A place where bricks are burnt. 
 
 Kink or Kinkle The entangling of cordage from overtwisting. 
 
 l,ateral A horizontal or lengthwise movement. 
 
 Lathe Machine used by turners. 
 
 Lantern A wheel with stafif-teeth j the trundle or 
 
 wallower. 
 
 Leaves The teeth of a pinion. 
 
 Lever One of the mechanical powers. 
 
 Line of centres A line drawn from the centre of one wheel to 
 
 the centre of another when their circum- 
 ferences touch each other. 
 
 Locomotive The power of changing place. 
 
 Loom A machine used by weavers in the making of 
 
 cloth. 
 
 Machinist One who makes machines. 
 
 Mandrpl Part of a lathe ; Cone used by smiths ; a 
 
 cylindrical piece of polished iron or steel 
 put down the core or hole of a pipe during 
 the process of elongation. 
 
 Mastering Preparation of lime used by tanners. 
 
 Matrice., , The concave form of a letter in which the 
 
 types are cast. 
 
 Alaximum.,,,^,,,,,, Is the utmost extent of any movement or 
 power. 
 
 Mechanist One acquainted with the laws of mechanics. 
 
 MilUhead The head of water which is to turn a mill. 
 
 MilLiail The water wdiich has passed through the 
 
 wheel- race ; or is below the mill. 
 
 Minimum The reverse of maximum. 
 
 Momentum The force possessed by matter in motion. 
 
 Monkey A weight or mass of iron let fall from a 
 
 height to drive piles into the earth. 
 
 Mortise A joint. 
 
 Movement Tfie w’orking part of a watch or clock. ’ 
 
 Nave, The centre, or that part, of a wheel in 
 
 which the spokes or arms are fixed. 
 
 Nealing. Vide Annealing. 
 
 Nippers Pincers with cutting edges for dividing 
 
 metals. 
 
 Nitric acid A corrosive acid extracted from nitre. 
 
 Ouse . Preparation of bark used by tanners. 
 
APPENDIX. 
 
 Overshot-'wheel, •••«•• 
 Oxyd. 
 
 Oxygen 
 
 Paddle 
 
 Pall 
 
 Pallet 
 
 Pendulum 
 
 Periphery. 
 
 Perpendicular 
 
 Pick 
 
 Pile .. 
 
 Pin 
 
 PincerSk 
 
 Pinion , , 
 
 Pirn 
 
 Piston, 
 
 Pitch-lines 
 
 Pitch of the wheel,, , , , 
 
 Pivot 
 
 Plalina .... 
 
 Pliers 
 
 Plumb ■ . . . . 
 
 Plunger * 
 
 Portable steam-engine . 
 
 779 
 
 A wheel which receives the water in buckets 
 at not more than 45 degrees from the 
 apex. 
 
 A combination of ox^rgen with a metallic or 
 other base. 
 
 A gas which supports combustion 
 
 A kind of oar j floats to a wheel. 
 
 A small piece of metal which falls between 
 the teeth of a ratchet-wheel, to prevent a 
 load which has been raised from descending 
 when the operative power is removed. 
 
 That part of a watch or clock escapement on 
 which the crown-wheel strikes. 
 
 A weight suspended by a flexible cord to an 
 axisj so as to swing backwards and for- 
 wards, when once raised, by the force of 
 gravitation. 
 
 The circumference of a wheel. 
 
 At right angles to a given base. 
 
 A chisel for dressing the stones of a flour- 
 mill. 
 
 A large pieee of timber, pointed at one end, 
 to drive into the earth to sustain the piers 
 of bridges, &c. 
 
 To strike a piece of metal with the narrow 
 end of a hammer to form dents and pro- 
 duce elongation. 
 
 A tool formed by placing two levers on one 
 fulcrum, regulated by a screw-movement, 
 for holding bodies firmly. 
 
 A small toothed wheel. 
 
 The wound yarn that is on a weaver’s shuttle. 
 
 A plug made to fit tight and work up and 
 down a cylinder in hydraulic engines. - 
 
 The touching circumferences of two wheels 
 which are to act on each other. 
 
 The distance from the centres of two teeth, 
 measured upon their pitch line. 
 
 A short shaft on which a body turns or vi^ 
 brates. 
 
 A white metal capable of withstanding great 
 heats. 
 
 A small tool constructed similarly to pincers, 
 
 A leaden w^eight suspended by a cord to as- 
 certain the perpendicular. 
 
 A body that is forced into a fluid in hydrau- 
 lic engines, to displace its own weight. 
 
 A steam-engine built in a compact form. 
 
780 
 
 APPENJ)IX. 
 
 and not attached to the wall of the build- 
 ing in which it works. 
 
 Proportional circles, Pitch-lines. 
 
 Proportional radii, , . • The radii of two circles whose circum- 
 ferences are in contact. 
 
 Puddling The act of ramming with clay to arrest the 
 
 progress of water. 
 
 Pulley A small wheel over which a strap is passed. 
 
 Quintal A French or Spanish weight equivalent to 
 
 1 OOlbs. of those respective nations. 
 
 Rahbit or Rap-it ^^ , . , . The strong wooden spring against which the 
 forge hammer strikes on its ascent. 
 
 Race The canal along which the water is conveyed 
 
 to and from a water-wheel. 
 
 Rack.,,*, A straight bar which has teeth similar to 
 
 those on a toothed wheel. 
 
 Radii. The plural of radius. 
 
 Radius • . The semi-diameter of a circle ; the arm or 
 
 spoke of a wheel. 
 
 Rasp. .r. A species of file, on which the cutting pro- 
 
 minences are distinct, being raised by a 
 point instead of an edge. 
 
 Rasure The act of scraping. 
 
 Batch A oar containing teeth into which the pali 
 
 drops to prevent machines running back. 
 
 Ratchet-wheel. . A wheel having teeth similar to those of $ 
 
 ratch. 
 
 Reciprocating,: , Acting alternately. 
 
 Rectilinear or Consisting of right lines. 
 
 Reed Part of a loom resembling a comb for divid- 
 
 ing the warp. 
 
 Regulator A small lever in watch-work, which, by be- 
 
 ing moved, increases or decreases the 
 amount of the balance spring tliat is al- 
 lowed to act. 
 
 Red. A frame on which yarn may be wound. 
 
 Reeling The act of winding yarn on a reel. 
 
 Resolution of Forces, . . Vide Of the Action of Forces,” page 5. 
 
 Reservoir A large basin or conservatory of water. 
 
 Reverberatory Beating back. 
 
 Reverberatory-furnace. A furnace used in the iron and copper inanu- 
 
 i factures. 
 
 Rivet To form a head by the percussion of a hams- 
 
 mer, to prevent a piece of metal which has 
 been passed through an orifice, to con^ 
 nect things together, from returning. 
 
 Roller^gin, , , #00.00 A machine to divest cotton of the husk and 
 
APl’ENDIX. 781 
 
 Other superfluous parts, previous to the 
 commencement of the manufacture. 
 
 Rotatory Revolving. 
 
 Rowans. Cotton in that part of the manufacture be- 
 
 fore it goes to the roving frame. 
 
 Ruller A heavy file used for coarse work. 
 
 Rubble A mode of building ; Masonry, page .537. 
 
 Rynd The piece of iron that goes across the hole 
 
 in an upper mill-stone. 
 
 Safety-valve, A valve which fits on the boiler of a steam- 
 
 engine to guard against accidents by the 
 steam obtaining too high a pressure. 
 
 Saw-gin A machine on the principle of the roller-gin. 
 
 Scantling The length, breadth, and thickness of any 
 
 solid body taken lineally. 
 
 Scapement Vide Escapement. 
 
 Scotching The operation of packing hemp before it 
 
 goes to the market. 
 
 Scoria Slag from a smelting furnace. 
 
 Scowering Barrel An octagonal, or other shaped barrel, in 
 
 which scrap-iron, &c. is cleansed from rust 
 by friction as it revolves. 
 
 Scrap-iron Various pieces of old iron to be re-manu- 
 
 factured. 
 
 Screw, ^ One of the mechanical powers. 
 
 Scribbler-Engine An engine used in the process of the cotton 
 
 manufacture. 
 
 Shaft A long piece of wood or metal, on which 
 
 large wheels are fixed in mill- work. 
 
 Sheeve A small kind of pulley. 
 
 Shoulder, A support by means of a projection from a 
 
 surface. 
 
 Shrouding The boards, &c. which form buckets of 
 
 water-wheels. 
 
 Shuttle An arrangement to allow or shut off water 
 
 from a water-wheel 5 a small piece of 
 wood which carries the thread in weaving. 
 
 getable substances, and applied to fibrous 
 materials to impart stiffness. 
 
 Slag Scoria, or refuse from an iron furnace. 
 
 Sledge-hammer ...... A heavy hammer, used by a smith with both 
 
 hands. 
 
 Slip Potter’s clay of the requisite consistency. 
 
 Sluice Vent for water j a kind of flood-gate 
 
 Snail-movement An eccentric. 
 
 Solder , . Various compounds of metals for conjoining 
 other metals that are less fusible than such 
 compound. 
 
APPENDIX. 
 
 782 
 
 Sparables From sparrow-bill^ small nails to drive intc 
 
 shoes. 
 
 Spatula A thin knife, used mostly to extend super- 
 
 ficially some semi-fluid matter. 
 
 Spindle A thin piece of wood or steel on which yarn 
 
 is wound after it has been twisted : a small 
 kind of shaft. 
 
 Spokes The radial pieces which connect the periphe- 
 
 ry of a wheel with its centre-piece or nave : 
 this term is only applied to carriages. 
 
 Sprins elastic body formed of metal or wood. 
 
 Sprina-arlor The arbor or spring round which the main 
 
 spring of a watch is w^ound. 
 
 Spring-l'ox The box which contains the main spring. 
 
 Spnr-geer Wheels whose axes are parallel to each other. 
 
 Splice To conjoin lengthwise two flexible pieces: 
 
 by the interposition of their respective 
 parts, so as to maintain them in conjunc- 
 tion by friction. 
 
 StajU'..,^^ The teeth of a trundle, lantern, or wal- 
 
 lower. 
 
 StaJiing-on To drive wedges in the bush of awheel or 
 
 pulley, to hx ^t firm on a shaft or spindle. 
 
 Start or Strut ........ The partitions which determine the form of 
 
 a bucket in an over-shot wheel j the 
 shoulder or WTest. 
 
 Staves The plural of staff. 
 
 Steam-boat A boat moved by steam power. 
 
 Steam-engine ......... A machine for applying the force of steam 
 
 to create motion. 
 
 Steel-yard A machine w'hich denotes the weight of bo- 
 
 dies by placing them at different distances 
 from its fulcrum. 
 
 Stereotype ' . ......... The art of casting solid plates from movable 
 
 types, to print from. 
 
 Strike A thing used to strike any thing level in a 
 
 measure : the strickle. 
 
 Strata The plural of stratum. 
 
 Stratum A single layer or bed of any one thing. 
 
 Stuff; This term is applied to an infinite variety of 
 
 things j wood is, by the carpenter, called 
 stuff, so is lime and hair by the bricklayer, 
 and plaster by the plasterer, &c. 
 
 ISwag . . An unequal or hobbling motion. 
 
 Sudifts . The rapid movement in a carding machine. 
 
 Stvingling Scotching. 
 
 Swing-tree Any beam that vibrates. 
 
 Swivel A thing fixed in another body to turn round 
 
 upon. 
 
APPENDIX* 7B3’ 
 
 Syphon A ])ent tube with unequal legs through which 
 
 a fluid will flow by the force of gravity. 
 
 Tail-water Water which impedes the water-wheel iu 
 
 mill- work. 
 
 Tank Reservoir for water, &c. 
 
 Teasels • Thistles used to raise the nap of cloth in the 
 
 , ^ gig-mill. 
 
 Tenon That j:)ait which fills up the mortise. 
 
 Tilt-hammer , » , A hammer lifted by machinery, to forge 
 iron or steel. 
 
 Treadle A lever affixed to a crank which communi-* 
 
 cates motion to machinery by a foot 
 movement. 
 
 ThroWsting Spinning. 
 
 Triblet Vide Mandrel. 
 
 Truckles Small rollers for diminishing friction. 
 
 Trundle A small wheel with staff teeth j the lan° 
 
 tern or waliower. 
 
 Tuyere or Tue-iron. . . An orifice through which a blast or strong 
 current of air is passed into forges 
 
 Tympati That part of a printing-press on which the* 
 
 paper is laid to receive the impression. 
 
 Undershot-wheel A wheel acted on by water below its centre. 
 
 Vacuum Void of air. 
 
 Valve A cover to an aperture, in hydraulic ma- 
 
 chines, to prevent fluids taking a WTong 
 course. 
 
 Vane A flat surface capable of being moved by the 
 
 current of a fluid j as, for instance, the 
 vanes of a wdndmill, moved by the wdnd. 
 
 Tappets Projections on the plug-tree of a steam-en- 
 
 gine w hich open and shut the valves at 
 proper intervals. 
 
 Varnish A solution of certain resinous bodies in spi- 
 
 rits or oils, w hich assumes a solid form on 
 dissication. 
 
 Velocity The measure of quickness with which a body 
 
 moves. 
 
 Vertical Perpendicular to the horizon. 
 
 Vibration .. Ripid alternating motion. 
 
 Virtual head ^The real or effective head. 
 
 Vis-inertia .... Vide Inertia. 
 
 Wabble A hobbling unequal motion. 
 
 Waliower Small wheel with staff teeth; the trundle 
 
 or lantern. 
 
 Warp The layer of threads which extends t'ne 
 
 length of the piece to be woven. 
 
 Washers Small pieces of metal placed under a nut ta 
 
 reduce friction. 
 
APPENDIX. 
 
 784 
 
 Walcr-wheel A wheel which receives its impulse ffora 
 
 water. 
 
 Weathering The angle at which the sails of a windmill 
 
 are set, to receive the impulse of the wind. 
 
 Wedge An angularly shaped piece of wood or me- 
 
 tal 5 one of the mechanical powers. 
 
 Weft Vide Woof. 
 
 Weight The measure of the amount of the attraction 
 
 of gravitation in any body compared with 
 that of other bodies. 
 
 Welding The property of conjunction possessed by 
 
 some metals at high temperatures. 
 
 Wheel and Axis One of the mechanical pow’ers. 
 
 Wheel-race The place in which a water-wheel is fixed. 
 
 Whip To bind two rods together with small twine : 
 
 the length of the sail of a windmill mea- 
 sured from the axis. 
 
 Whirl A rotatory motion with a decreasing speed. 
 
 Winch The lever or handle to which force is applied 
 
 in machines turned by manual labour. 
 
 Wiper An eccentric. 
 
 fVire-draw To reduce any longitudinal body exceedingly 
 
 in the transverse section : rapid passage 
 of a fluid through a conical orifice. 
 
 Woof, Those portions of thread or yarn in clotiiy 
 
 which lie across the length of the warp. 
 
 Wrest or Wrist , . 4. , , The partitions which determine the form of 
 the bucket in an overshot wheel 3 tha 
 start or shoulder. 
 
 Yarn The combination of fibrous materials into n, 
 
 linear form by torsion* 
 
INDEX 
 
 Page. . Page. 
 
 Accelerated MOTION . . 3 Assay to, Silver, to ascertain the 
 
 Amalgam, to gild copper, &c. by, 723 value 763 
 
 Amalgamation of gold, in the Double assay of, . , . ib» 
 
 large way ....... 719 Silver ores 762 
 
 Fat, or copal 742 in the humid way . . 763 
 
 with essence of turpentine 741 Tin ores 758 
 
 Ancient statues, composition of, 713 in the humid way . . ib. 
 
 Anti-attrition 755 Zinc ores i5. 
 
 Assay to, metallic ores, . . ib. in the humid way ... ib. 
 
 in the dry way ... ib. 
 
 in the humid way . ' . 756 Balloons, to varnish, . . . 750 
 
 Fluxes ib. Bark-mill . 445 
 
 Black ib. Barker’s mill 92 
 
 Crude of wdiite . . • t '>. Batter 379 
 
 Cornish reducing ... ib. Bath metal 707 
 
 Cornish refining ... ib. Bell metal 708 
 
 Antimonial ores .... 760 Bricklaying, vide Building 
 
 humid assay of arseniated Britannia metal . ..... ib. 
 
 antimony .... ib. Bronze ........ 713 
 
 Arsenical ores .... ib. Composition of ancient statues ib. 
 
 in the humid way . . , 760 Engine 218 
 
 Cinnabar, in the humid way, 762 Buildino 
 
 Cobalt ores 761 Preliminary Observations . 529 
 
 in the humid way . . . ib. Bricks 532 
 
 Copper ores .... 759 Cartwright’s .... 535 
 
 in the humid way . . ib. Clamps 533 
 
 Gold, mixed with martial Clay-mill i5, 
 
 pyrites, do. .... 765 Kiln 534 
 
 Ores and earths contain- Bricklaying 547 
 
 ing 764 Mensuration of Bricklayers' 
 
 Iron ores 757 work 550 
 
 in the humid way . . ib. Steining wells .... 549 
 
 in the humid way . . 759 tions 556 
 
 Manganese ore .... 760 Walling 547 
 
 in the humid way . . ib. English bond .... ib» 
 
 Mercurial ores .... 761 Flemish bond .... ib. 
 
 sulphurated .... 762 Carpentry ....:. 560 
 
 in the humid way . . ib. ters 572 
 
 Plated metals .... 764 Camber-beam . . ib, 
 
 3 E 
 
786 
 
 INDEX 
 
 Building, Carpentry 
 
 Cocking, or cogging 
 
 57.S 
 
 Building, Joinery 
 
 To bend a board so as to 
 
 
 Domes 
 
 575 
 
 form the frustrum of a cone, 
 
 
 •Joggles 
 
 573 
 
 or any segmental portion 
 
 
 King-post 
 
 Niches 
 
 572 
 
 of the frustrum of a cone . 
 
 587 
 
 577 
 
 To glue up the shaft of a co- 
 
 
 Predentive cradling 
 
 578 
 
 lumn, supposing it to be the 
 
 
 Pole-plates 
 
 572 
 
 frustrum of a cone . . . 
 
 ib. 
 
 Puncheons 
 
 ib. 
 
 Dovetailing 
 
 588 
 
 Purlines 
 
 571 
 
 Best methods of connecting 
 
 
 Rafters, auxiliary, . . 
 
 .572 
 
 pieces of wood so as to form 
 
 
 Common 
 
 ih. 
 
 an angle 
 
 589 
 
 Principal .... 
 
 571 
 
 Measures customary in join- 
 
 
 Queen- Posts .... 
 
 572 
 
 ers’ work 
 
 602 
 
 Roofs 
 
 57.3 
 
 Doors, bead and flush . . 
 
 590 
 
 St raining- beam . . . 
 
 572 
 
 Hanging 
 
 ib. 
 
 Cilt 
 
 ib. 
 
 Jib 
 
 589 
 
 Struts . .... 
 
 ib. 
 
 Hand-rails 
 
 599 
 
 Tie-beam 
 
 571 
 
 To draw the sjcroll . . 
 
 598 
 
 Wall-plates .... 
 
 ib. 
 
 To describe the section, . 
 
 599 
 
 Flooring 
 
 569 
 
 Hinging 
 
 591 
 
 Framing of centres for 
 groins 
 
 
 Hanging doors, shutters, 
 and flaps, with hinges . 
 
 ib. 
 
 Joining two timbers in any 
 given direction . . . 
 
 563 
 
 1 To hang 2 flaps, so that 
 
 when folded back, they 
 
 
 by mortise and tenon 
 
 564 
 
 shall be at a certain dis- 
 
 
 by a notched joint . . 
 
 ib. 
 
 tance from each other 
 
 ib. 
 
 of timbers, with reference 
 to plate 
 
 557 
 
 1 0 make a rule-joint for 
 a window'-shutter 
 
 592 
 
 Mensuration of Carpenters’ 
 w'ork 
 
 579 
 
 To form the joints ofsti'es 
 to be hung togetlier,wiien 
 
 
 Partitions 
 
 569 
 
 tile knuckle of the hinge 
 
 
 Practical Observations . . 
 
 570 
 
 is placed on the contrary 
 
 
 Roofing .... 
 
 569 
 
 side of the rebate . . 
 
 ib. 
 
 Roofs defined .... 
 
 573 
 
 To construct a joint for 
 
 
 Timbers inserted in w'alls . 
 
 568 
 
 hanging doors w ilh cen- 
 
 
 Scarfing. Joining 2 pieces 
 
 
 tres 
 
 ib. 
 
 of timber by means of a 
 single step on each piece 
 
 561 
 
 Sadi-frames, sashes and 
 slmtteis ...... 
 
 592 
 
 vScai f with parallel joints, 
 
 
 Stairs 
 
 593 
 
 and a single table upon 
 
 
 Bracket 
 
 595 
 
 each piece 
 
 562 
 
 Dog-legged 
 
 597 
 
 Scarf formed by several 
 
 
 Geometrical .... 
 
 596 
 
 steps 
 
 ib. 
 
 Ditto 
 
 598 
 
 Scarf with a bevel joint . 
 
 ib. 
 
 I'o draw the scroll of a 
 
 
 Scarfs w'ith long bcari.*igs 
 
 ib. 
 
 hand-rail 
 
 
 Trussing 
 
 ib. 
 
 To draw the curtail steps 
 
 ib. 
 
 Girders to sustain very 
 heavy weights .... 
 
 563 
 
 To find the parallel thick- 
 ness of the plank . 
 
 599 
 
 Walls, limbers inserted into, 
 
 568 
 
 I'o describe a section of 
 
 
 Glazing ...... 
 
 635 
 
 a hand-rail 
 
 ib. 
 
 Mensuration of Glaziers’ 
 
 
 Masonry 
 
 536 
 
 work 
 
 630 
 
 Arching 
 
 541 
 
 Joinery. To construct the 
 surface of a portion of a cy- 
 
 
 Definition of arches and 
 vaults 
 
 
 linder, with wood, when 
 
 
 Mensuration of masons’ work 543 
 
 the fibres are at right 
 
 
 Masonry. Wailing . . . 
 
 537 
 
 ancles to the axis of the cy- 
 
 
 Painting 
 
 630 
 
 linder 
 
 586 
 
 Mensuration of Painters’ work ib. 
 
INDEX. 
 
 787 
 
 Page. Page. 
 
 Building Copper, blanched, .... 710 
 
 Plastering 605 To gild, by amalgam . . . 723 
 
 Cornices 615 Tin 726 
 
 Fine stuff 611 Cotton manufacture .... 378 
 
 Gauge stuff ib. Batter 379 
 
 Lathing ib. Jenny spinning . . . . • 384 
 
 Lathing, floating, and set . 612 Carding-engine .... 385 
 
 Lathing, laying, and set . . ib. Jenny .... . . 386 
 
 Laying ib. Roving Billy ib. 
 
 Lime and cement . . . 607 Mule spinning 379 
 
 Lime and hair . . . . 610 Bobbin and flier roving- 
 
 Parker’s cement .... 618 frame 383 
 
 Plaster of Paris .... 609 Breaker carding engine . 380 
 
 Pricking up 612 Carding engine .... ib. 
 
 Rendering and set . . . 613 Drawing 382 
 
 Roughcasting .... 614 Finisher engine .... 381 
 
 Scagliola 615 Mule spinning frame . . 384 
 
 Stucco 617 Roving frame .... S82 
 
 Plumbing 628 Stretching frame .... 383 
 
 L#^ad 629 Picker 37 9 
 
 Sheet 630 Roller gin 378 
 
 Covering roofs with, . 633 Saw gin . ib. 
 
 Pipes ib. Water spinning 386 
 
 Mensuration of plumbers’ Reel 337 
 
 work 635 Spinning frame .... ib. 
 
 Pomps ib. Throstle . . ... ib. 
 
 Slating 621 Coupling. Boring Mill clutch . 31 
 
 Mensuration of Slaters’ work 627 Boulton and Watt’s coupling 
 
 link . . . ' 32 
 
 Carpentry, vide Building Clutches or Glands .... 31 
 
 Centrifugal force 4 Self-easing coupling . . . ib. 
 
 Centripetal force ib. Square, with double bearings . 30 
 
 Chain of buckets 86 one bearing . , . ib. 
 
 Chain pump 267 Round ib. 
 
 by Cole ib. Crane 283 
 
 reversed . . .... 86 by Bramah 287 
 
 Chinese sheet lead 527 Ferguson 286 
 
 Chronometers 507 Padmore 285 
 
 Cider-press 291 Foot . ib. 
 
 Clock 486 Movable, by Kier .... 288 
 
 with three wheels and two pi- Cycloid, to describe the, . . 21 
 
 nions, by Dr. Franklin . 490 
 
 by Ferguson ... ib. Darwin’s engine 232 
 
 for exhibiting the apparent Dearborn’s pump engine - , 244 
 
 daily motions of the sun and De la Faye’s machine . . . 229 
 
 moon, state of the tides, &c. 492 Desagulier’s drawer and bucket 242 
 
 Striking part of an eight day Describe to, the cycloid and 
 
 clock 496 epicycloid 21 
 
 Description of curious clocks 497 Disengaging and re-engaging 
 
 Colour and indigo mills . . . 454 machinery ...... 32 
 
 Composition of ancient statues 713 Bayonet 33 
 
 Copal varnish, camphorated, . 739 Fast and loose pulley ... ib. 
 
 Colourless 738 Friction clutch 34 
 
 Ethereal 740 Friction cone ib. 
 
 Fat 737 Lever S3 
 
 Fat Amber 742 Self-disengaging coupling . 35 
 
 Gold-coloured 738 Sliding pulley S3 
 
 Turpentine 740 Tightening roller .... 34 
 
 White 731 Dividing machine by Ramsden 315 
 
788 
 
 INDEX 
 
 Pa?e, 
 
 Drying oil, resinous . , , . 737 
 
 To give a drying quality to fat 
 
 oils 736 
 
 to poppy oil .... 735 
 Drawings or writings, &c. to 
 gild on paper or parchment . 721 
 
 To varnish 750 
 
 To prepare a composition 
 for making coloured 
 drawings and prints re- 
 semble paintings in oil . 750 
 
 Varnish for coloured, . . 749 
 
 Dressing boxes, caniphorated 
 
 sandarac varnish for, . . 744 
 
 To varnish, 747 
 
 Elastic Gum, to dissolve . . 732 
 
 Engravings on copper, metallic 
 
 casts from 712 
 
 Epicycloid, to describe . . 21 
 
 Equalizing the motion of machi- 
 nery 35 
 
 Governor for steam-engine 36 
 Water-wheel . 37 
 
 Ditto . . . 113 
 
 Wind-mill . 124 
 
 '^I’achometer by Donkin . 39 
 
 General Observations . . 43 
 
 Escapement 515 
 
 llecoiling 516 
 
 > by Cumming 517 
 
 for watch 518 
 
 by Pryor 519 
 
 Keid 521 
 
 i De la Fons 524 
 
 File-cutting Machine . . . 314 
 Fire-engine by Newsham . . 277 
 
 by Rowntree. . . 281 
 
 Flax manufacture .... 400 
 
 Brake 401 
 
 Flax-mills 403 
 
 Foot brake ...... 401 
 
 Hackle 402 
 
 Rippling comb 403 
 
 Spinning by Kendrew and Co. 405 
 Clarke and Bugby . . . ib. 
 
 Flour-mills 142 
 
 Family mill and bolter by Rus- 
 
 tall 158 
 
 by Smart 160 
 
 Fenwick’s Tables .... 148 
 
 Foot-mill ]6l 
 
 Hand-mill 160 
 
 Kneading-mill 162 
 
 Mill Slones 144 
 
 Observations 148 
 
 Flute-key valves, metal fur, . 711 
 
 Page. 
 
 Fluxes, to assay by, .... 756 
 
 Black ........ ib. 
 
 Crude of white ib. 
 
 Cornish reducing .... ib. 
 
 Cornish refining .... ib. 
 
 Foils 715 
 
 To prepare the copper . . ib. 
 
 To whiten ib. 
 
 To colour 716 
 
 Amethyst . . ... 717 
 
 Blue ib. 
 
 Eagle marine . . . . ib. 
 
 Garnet ib. 
 
 Green ib. 
 
 Ruby ib» 
 
 Yellow ib. 
 
 Other colours _^ib. 
 
 For crystals, pebbles, or 
 
 paste 716 
 
 Force, centrifugal 4 
 
 Centripetal ..... ib. 
 
 Forces, of the action of . . 1 
 
 Forge hammer 335 
 
 Friction 6 
 
 Furnace, Blast, 330 
 
 Puddling 335 
 
 Refining 334 
 
 Steel 843 
 
 Fusible metals 707 
 
 747 
 
 216 
 
 Gallipot Varnish . . 
 
 Gas engine, by Brown 
 Geering, vide Mill-geering 
 
 Geometry 673 
 
 Problems in, 681 
 
 Gilding, Grecian 719 
 
 Gold powder for, .... 718 
 
 Mordant varnish for, . . . 748 
 
 Oil, on wood, . . . . 722 
 
 To cover bars of copper with 
 gold, so as to admit of being 
 rolled out into sheets . . 718 
 
 To^dissolve gold in aqua re- 
 gia 719 
 
 Gild to, by amalgamation . . 720 
 
 by burnishing 723 
 
 in colours 719 
 
 by dissolving gold in aqua re- 
 gia ib. 
 
 Copper, &e. by amalgam . 723 
 Glass and porcelain . . . 720 
 
 Iron or steel 719 
 
 Leather .721 
 
 Silk, satin, &c. by hydrogen 
 
 gas 722 
 
 Steel 724 
 
 Gild to, writings, drawings, &c. 
 
 on paper or parchment . 721 
 
 The edges of paper . . • 722 
 
INDEX. 
 
 Page. 
 
 Gilding metal 714 
 
 For common jewellery . . ib. 
 
 Yellow dipping metal . . ib. 
 
 Glass and porcelain, to gild . 720 
 Globes, liquid foil for silvering 772 
 
 glass, 728 
 
 Glossary . . 772 
 
 Gold, useful alloy with platinum 713 
 from 35s. to 40s. per ounce . 714 
 
 Manheim gold, or similor . ib. 
 
 Ring ib. 
 
 Amalgam of gold in the large 
 
 way 719 
 
 To dissolve gold in aqua regia ib. 
 ' To separate from gilt copper 
 
 and silver 724 
 
 Gold, green, to heighten the co- 
 lour of ib. 
 
 Gold, red, ditto ib. 
 
 Gold, yellow, ditto .... ib. 
 Golden, or fat turpentine var- 
 nish 746 
 
 Gravity, of the centre of . . 15 
 
 Gun barrels, to brown . . . 731 
 
 Gun metal 710 
 
 H‘ckle 402 
 
 Hand-mill 160 
 
 Hand-pump by Martin . . . 269 
 
 Jekyl .... 270 
 Hemp and rope manufacture . 416 
 
 Reetling 419 
 
 Brealle’s r>iethod of steeping . 418 
 
 Dew retting 417 
 
 Hemp-Mill 419 
 
 Raiobeard’s method of steep- 
 ing ib. 
 
 Swingling or scotching . . 420 
 
 Hiero’s Fountain 232 
 
 Horizontal windmill .... 139 
 
 Horology ... ... 486 
 
 Chronometer 507 
 
 Clock with three wheels and 
 two pinions, by Dr. Frank- 
 lin 490 
 
 by Ferguson . ib. 
 for exhibiting the apparent 
 daily motions of the sun, 
 moon, and tides .... 492 
 
 Striking part of an eight 
 
 day, 496 
 
 Description of curious 
 
 clocks 497 
 
 Escapement 515 
 
 Recoiling 516 
 
 by Camming .... 517 
 
 for watch 518 
 
 by Pryor 519 
 
 Reid 521 
 
 789 
 
 Page. 
 
 Horology. Escapement 
 
 by De la Fons .... 524 
 Pendulum 525 
 
 Gridiron, by Harrison . . 527 
 
 Lever by Ellicott . . . ib. 
 
 Mercurial by Graham . . 526 
 
 Tubular by Reid . . . 529 
 
 by Troughton . 528 
 
 by Ward ... 529 
 
 Sympathy of the pendulums 
 
 of clocks ib. 
 
 Watches . • 500 
 
 Table of trains for, .... 504 
 
 Hungarian machine .... 233 
 
 improved by Boswell . . . 235 
 
 Hydraulics, Archimedes’ screw 246 
 Darwin’s engine .... 232 
 
 Dearborn’s pump engine . . 242 
 
 De la Faye’s machine . . . 229 
 
 Desagulier’s drawer and buck- 
 et 242 
 
 Hiero’s fountain ..... 232 
 
 Hungarian machine .... 233 
 
 improved by Boswell . . 235 
 
 Noria 230 
 
 Paternoster wmrk .... 231 
 
 Persian wheel 230 
 
 Spiral pump 237 
 
 Trevitheck’s pressure engine 246 
 
 Tympanum 228 
 
 Fire engine by Newshani . . 277 
 
 by Rountree . , 281 
 
 Pump 250 
 
 Chain 267 
 
 by Cole ib. 
 
 Hand, by Martin . . . 269 
 
 by Jekyl . ... 210 
 
 Forcing 257 
 
 by Brunton . . . 263 
 
 Franklyn ..... 262 
 
 Smeaton 265 
 
 Stevens ----- 259 
 
 Tyror 261 
 
 Lifting ------ 258 
 
 Suction ------ 250 
 
 with little friction - - 255 
 by Ctesebius - - - - 259 
 Taylor ----- 256 
 
 Todd - - ib. 
 
 Method of working ships’ 
 pumps by Leslie - - - 268 
 Clarke - - 273 
 Pump pistons by Belidor - 276 
 Bonnard - 274 
 Hydrostatic press by Bramah - 292 
 
 Inclined PEANE, the - - - 12 
 
 Index - - - 785 
 
 Indigo-mill ------- 454 
 
700 INDEX. 
 
 Page. Page. 
 
 Inertia - -- -- -- - 32 Mastic varnish, compound, . 742 
 
 Internal pinion ----- 27 Camphorated, for painting . 743 
 
 Iron manufacture - - - - 328 Mechanical powers .... 7 
 
 Blastfurnace ----- 330 Inclined plane . . • . . 12 
 
 Forge hammer ----- 33.5 Lever 7 
 
 Puddling furnace - - - - ib. Pulley . , ; 11 
 
 Refining furnace - - - - 334 Screw ........ 13 
 
 Re-manufacture - _ - - 338 Wedge ib. 
 
 Tilt-hammer 335 ‘ Wheel and axle .10 
 
 Tables of the average weight Simple combinations of the, . 16 
 
 of squares, bolts, and bars - 339 Mensuration of Superficies , . 688 
 Iron, expeditious inode of re- Solids .... 697 
 
 docing iron ore into mal- Metal for flute key valves . . 711 
 
 leable iron ------ 768 Metallic casts from Engravings 
 
 New method of shingling and on copper 712 
 
 manufacturing - - - - ib. Ores, to assay, .... 755 
 
 To plate ------ 726 in the dry way .... ib. 
 
 To weld ------ 769 in the humid way . . . 756 
 
 To harden ----- ib. Watering, or for Blanc Noire 727 
 
 To case-harden - - - - ib. Mill-geering 20 
 
 To convert iron into steel by To describe the cycloid and 
 
 cementation - - - - ib. epicycloid ..... 21 
 
 To'make edge-tools from cast , Couplings 30 
 
 steel andiron - - - 771 Boring-mill clutch . . , [ 31 
 
 To distinguish iron from steel ib. Boulton and Watt’s coup- 
 
 Ivory, to gild, by hydrogen gas 722 ling link S2 
 
 Clutches or glands ... SI 
 
 Jacks, common ----- 282 Round ....... 30 
 
 Screw ------ 283 Square with double bearings ib. 
 
 Jenny spinning ----- 384 with one bearing . . . ib. 
 
 Carding engine - - - - 885 Self-easing coupling . . 31 
 
 , Jenny ------- S 86 Universal joint .... 32 
 
 Roving Billy - - ~ - ib. Double universal joint . . ib. 
 
 Joinery, vide Building. Dis-engaging and re-engaging 
 
 machinery ib. 
 
 Kneading-mill ----- 162 Bayonet 33 
 
 Kiistitien’s metal for tinning - 710 Fast and loose pulley . ib. 
 
 Friction clutch .... 34 
 
 Lathe, by Maudesley - - - 323 Friction cone .... ib. 
 
 Smart ------- 326 Lever 33 
 
 Lacquer for brass - - - - 729 Self-disengaging coupling 35 
 
 for philosophical instruments ib. Sliding pulley 33 
 
 for brass watch-cases, &c. - 730 Tightening roller .... 34 
 
 of various tints - - - - 731 Equalizing the motion of ma- 
 chinery 35 
 
 Lead manufacture .... 356 Governor for sleam engine 36 
 
 Method of extracting the sil- water-wheel . 37 
 
 ver 359 ditto ... 113 
 
 Sheet lead - 360 Wind-mill . 124 
 
 Lead pipe 362 Tachometer by Donkin . 39 
 
 by Wilkinson .... 363 General observations . . 43 
 
 Lead, Chinese sheet . » . . 727 Teeth of wheels .... 23 
 
 Lead tree, to prepare the, . - ib. Spur geer ib. 
 
 Leather, to gild, 721 Bevel geer 23 
 
 Lever, the . 7 Mordant varnish for gilding . 743 
 
 Combinatioris of the, ... 16 Mule spinning 379 
 
 Locomotive engines and rail- Bobbin and flier roving frame 383 
 
 roads . ' 643 Breaker carding engine . . 380 
 
 Masonry, vide Building Carding engine ib. 
 
INDEX 
 
 791 
 
 Page. Page. 
 
 Mnle-spilining Painters’ cream - . - - 743 
 
 Drawing Painting, vide Building 
 
 Finisher engine .... 381 Paintings, cainphorated mastic 
 
 INInle spinning frame . . . Sb-l varnish for ------ 743 
 
 Foving frame 382 Paper manufacture - - - - 365 
 
 ^Stretching frame .... 383 by Dickenson ----- 37 1 
 
 by Fouidrinier - - - _ ih. 
 
 Noria 230 Cutting and planing machine 370 
 
 Press - 291 
 
 Oil-mill 447 Paper, to gild the edges of, - 722 
 
 Oil, gilding on wood .... 722 Paper works, camphorated san- 
 
 Poppy,togiveadryi'ogquality to 735 darac varnish for - - - - 744 
 
 Fat, ditto ditto , . 736 Parting - -- -- -- - 765 
 
 Resinous, drying .... 737 by aqua fortis ----- ih 
 
 Ores, to assay 755 by cementation . . _ - 766 
 
 in the dry way .... ib. in the humid way - - - - -ib, 
 
 humid way .... 756 Paternoster work - - - _ 231 
 
 Antimonial 760 Pendulum - - - - - - - 525 
 
 humid assay of arseniated Gridiron, by Harrison - - 527 
 
 antimony .... ib. Lever, by Ellicott - - - - jb, 
 
 Arsenieal ...... ib. Mercurial, by Graham - - 526 
 
 in the humid way . . .761 Tubular, by Reid - - - - 529 
 
 Bismuth ores .... 759 by Trough ton - - 528 
 
 in the humid way ... 760 by Ward - - - - 529 
 
 Cinnabar, in the humid way 762 Sympathy of the pendulum of 
 
 Cobalt 761 clocks , 5 , 
 
 in the humid way . . . ib. Penstock by Quayle - - - - 109 
 
 Copper 759 Smcatou - - - no 
 
 in the humid way . . . ib. Persian wheel 230 
 
 Gold, ores and earths con- Pewter, common 712 
 
 taining 764 best ib. 
 
 mixed with martial py- hard ib. 
 
 riles, in the humid way 765 Picker 379 
 
 Iron 757 Pile engine by Vaulou4 . - . 309 
 
 in the humid way . . . ib. by Buiice . . . 310 
 
 Lead 758 Pinchbeck 708 
 
 in the humid way . . . 739 Plaster figures, to bronze . . 731 
 
 Manganese 760 Plastering 606 
 
 in the humid way . . . ib. Cornices 615 
 
 Mercurial 761 Fine stuff 611 
 
 Sulphurated .... 762 Gauge stuff ib. 
 
 Nickel 761 Lathing ib. 
 
 in the humid way . . . ib. Lathing, floating, and set . . 612 
 
 Silver 762 Lathing, laying, and set . . ib. 
 
 by ciipellation .... ib. Laying ib. 
 
 in the humid way . . 763 Lime and cement . . . 607 
 
 Tin 758 Lime and hair .... 610 
 
 in the humid way . . . ib. Parker’s cement , . . . 618 
 
 Zinc ores ih. Plaster of Paris .... 609 
 
 in the humid way . . . ib. Pricking np 612 
 
 Overshot-wheel 75 Rendering and set . . . 613 
 
 with forty buckets .... ib. Roughcasting .... 614 
 
 Smeaton’s experiments on, • 79 Scagliola 615 
 
 by Burns 84 Stucco 617 
 
 Chain of buckets .... 86 Plate, to iron 726 
 
 Chain pump reversed • • • ib. Plated metals, to assay . . . 764 
 
 Method of laying on vi'ater, by Platina, mock 7 l 3 
 
 Noitaille Ill J^latinum, useful alloy of gold 
 
 inYoikshire 112 with H, 
 
7‘)2 
 
 INDEX 
 
 Page. 
 . . 709 
 
 Page. 
 
 Plumbing 62S 
 
 Lead 629 
 
 Sheet 630 
 
 Covering roofs with, . 633 
 
 Pipes ib. 
 
 Mensuration of plumbers’ 
 
 work' 633 
 
 Pumps lb. 
 
 Pneumatic or vacuum engine . 2)6 
 
 Poppy oil, to give a dry quality to 735 
 Porcelain and glass, to gild . . 720 
 
 Pottery 456 
 
 Bamboo coloured .... 483 
 
 Black Egyptian ib. 
 
 Black printed 475 
 
 Blue printed 482 
 
 Ditto 469 
 
 Biscuit oven 468 
 
 Biscuit painting .... 469 
 
 Cream coloured .... 480 
 
 China, Felspar. . ... 479 
 
 Iron-stone ib. 
 
 Drab coloured 484 
 
 Engine lathe 464 ( 
 
 Felspar China 479 
 
 Fine red 482 
 
 Flint mill 458 
 
 Frit 472 
 
 (lilding 475 
 
 Glazes 471 
 
 Iron-stone China .... 479 
 
 Jasper 483 
 
 I.ustre ware 476 
 
 Lustre Black ib. 
 
 Porcelain 478 
 
 Red by Meigh 477 
 
 Fine 482 
 
 Riley’s black lustre .... 476 
 
 Slip kiln 459 
 
 Stone China . t . . . . 479 
 
 Throwing wheel .... 461 
 
 Turning Lathe .... 463 
 
 Press 291 
 
 Bank Note, by Bramah . . 305 
 
 Cider 291 
 
 Double, by Peek .... 292 
 
 Hydrostatic, by Bramah . . ib. 
 
 Paper-mill 291 
 
 Printing, by Bacon and Don- 
 kin 301 
 
 by Deffeine . . . 298 
 
 by Ruthven . . . ib. 
 
 by Stanhope . . 294 
 
 Prince’s metal 708 
 
 Printers’ types 711 
 
 Stereotype plates and small 
 
 types . ib. 
 
 Printing press, vide Press 
 Pulley, the 
 
 Quekn’s metal 
 
 Rack and Pinion 27 
 
 Rail Roads and locomotive en- 
 gines 643 
 
 by Palmer 644 
 
 Losh and Stephenson . . ib. 
 
 Birkenshaw 650 
 
 Losh 651 
 
 Blenkinsop 654 
 
 Brunton 655 
 
 Sylvester’s report on . . . 656 
 
 Stevenson’s and Wood’s ex- 
 
 periments 663 
 
 Roberts’s experiments . . 664 
 Stationary engines . . . 670 
 
 Ramsden’s dividing machine . 315 
 
 Receipts, useful 707 
 
 Red gold, to heighten the colour 
 
 of 724 
 
 Roller gin 378 
 
 Rope manufacture 4ld 
 
 Beetling the hemp .... 419 
 Brealle’s method of steeping 
 
 ditto 418 
 
 Dew Retting 4i7 
 
 Duncan’s rope making . . 420 
 
 Hemp-rnill 4l9 
 
 Rainbeard’s method of steep- 
 ing hemp ib. 
 
 Swingling or scotching the 
 hemp 420 
 
 Sandarac varnish .... 743 
 
 Saw-gin 378 
 
 Saw-mills 441 
 
 by Smart 445 
 
 Scapement .' 515 
 
 Recoiling 516 
 
 by Camming 517 
 
 for watch 518 
 
 by Reid 5l9 
 
 Ditto 521 
 
 De la Fons 524 
 
 Sheet lead, Chinese .... 727 
 
 Silk manufacture 392 
 
 Doubling machine .... 399 
 
 Silk reel 393 
 
 Throwsting-mill 396 
 
 Winding machine .... 395 
 Silk, satin, &c., to gild by hydro- 
 gen gas 722 
 
 Silver to, assay 763 
 
 Double assay of ib. 
 
 Parting by aqua fortis . . . 765 
 
 by cementation .... 767 
 in the dry way .... ib» 
 
 Imitation of 714 
 
 To separate from plated copper 725 
 
 11 
 

 
 
 INBHX. 
 
 793 
 
 
 
 Pago. 
 
 Page. 
 
 Silver to, copper ingots 
 
 
 
 725 
 
 Stereotype plates - - - 
 
 711 
 
 in the cold way . . 
 
 
 
 ib. 
 
 Strength of materials 
 
 218 
 
 Silvering glass globes, liquid foil 
 
 
 
 
 for 
 
 
 
 728 
 
 Tachometer by Donkin 
 
 39 
 
 Silver-tree, to prepare the 
 
 
 726 
 
 Teeth of wheels . - 
 
 23 
 
 Simple combinations of the 
 
 me- 
 
 
 Spur geer - - - , 
 
 ib. 
 
 cbanical powers . . 
 
 
 
 16 
 
 Wheel and Trundle - 
 
 24 
 
 Slating, vide Building 
 
 
 
 
 To describe teeth for ditto 
 
 
 Solder, common . . 
 
 
 
 712 
 
 by circular arcs 
 
 ib. 
 
 Soft 
 
 
 
 ib. 
 
 Wheel and pinion 
 
 ib. 
 
 for steel joints . . 
 
 
 
 ib. 
 
 Leader and follower - 
 
 25 
 
 Brass solder for iron 
 
 
 
 713 
 
 Follower with staff teeth - 
 
 ib. 
 
 Gold .... 
 
 
 
 ib. 
 
 Wheels which combine the 
 
 
 Silver solder for jewellers 
 
 
 ib. 
 
 advantages of both pinion 
 
 
 Specula of telescopes . 
 
 
 . 
 
 710 
 
 and trundle - - - 
 
 26 
 
 Spiral fkump . . . 
 
 
 
 237 
 
 Internal pinion 
 
 27 
 
 Spur geer .... 
 
 
 
 23 
 
 Rack and pinion 
 
 ib. 
 
 Statues, composition of ancient 
 
 713 
 
 Bevel geer - - - - 
 
 28 
 
 Steam engine . . . 
 
 
 
 164 
 
 Throwsting-niill - - - 
 
 396 
 
 by Beighton . . . 
 
 
 
 169 
 
 Tide-mills - 
 
 94 
 
 Hornblower . . 
 
 
 
 182 
 
 I'ilt hammer - 
 
 
 Newcomen . . 
 
 
 
 168 
 
 Tinning, Kustitien’s metal for - 
 
 710 
 
 Savary .... 
 
 
 
 166 
 
 Tin to, copper and brass - 
 
 726 
 
 Watt .... 
 
 
 
 170 
 
 Iron and copper vessels - 
 
 fb. 
 
 Woolf .... 
 
 
 
 191 
 
 Lead pipe - 
 
 ib. 
 
 Boiler - - - 
 
 _ 
 
 - 
 
 181 
 
 Tin-tree, to prepare the - 
 
 ib. 
 
 Crank and fly wheel 
 
 - 
 
 _ 
 
 170 
 
 Tombac - . _ . 
 
 710 
 
 Eccentric motion - 
 
 - 
 
 _ 
 
 178 
 
 Red 
 
 ib. 
 
 Four-way cock 
 
 . 
 
 - 
 
 174 
 
 White - - 
 
 ib. 
 
 Parallel motion - 
 
 - 
 
 - 
 
 179 
 
 Tortoise - shell, imitation for 
 
 
 Pistons - 
 
 . 
 
 . 
 
 177 
 
 watch-cases _ _ . 
 
 738 
 
 Plug-tree 
 
 - 
 
 _ 
 
 ib. 
 
 Turner’s varnish for box-wood 
 
 746 
 
 Steam gauge - 
 
 - 
 
 . 
 
 181 
 
 Tutania or Britannia metal 
 
 708 
 
 Sun and planet wheels 
 
 - 
 
 . 
 
 169 
 
 German - 
 
 709 
 
 Valves, concentric 
 
 _ 
 
 _ 
 
 177 
 
 Spanish - 
 
 ib. 
 
 ditto - - 
 
 - 
 
 . 
 
 176 
 
 Engestroom - - - - 
 
 ib. 
 
 by Murray 
 
 - 
 
 - 
 
 175 
 
 Trevitheck’s pressure engine - 
 
 246 
 
 Safety 
 
 - 
 
 - 
 
 167 
 
 Tympanum - 
 
 228 
 
 System of 
 
 - 
 
 - 
 
 175 
 
 
 
 by Woolf - 
 
 - 
 
 - 
 
 204 
 
 UNDERSHOT-W'heel - - - 
 
 65 
 
 Bell-crank engine 
 
 - 
 
 - 
 
 205 
 
 by Lambert . « . 
 
 72 
 
 High-pressure engine 
 
 - 
 
 - 
 
 207 
 
 Smeaton’s experiments on 
 
 67 
 
 Locomotive engine 
 
 - 
 
 - 
 
 209 
 
 Rules for constructing, by 
 
 
 Ditto - 
 
 _ 
 
 - 
 
 ib. 
 
 Ferguson 
 
 114 
 
 Rotatory engine 
 
 - 
 
 _ 
 
 206 
 
 Brewster 
 
 117 
 
 Vibrating engine 
 
 - 
 
 - 
 
 ib. 
 
 Universal joint _ _ - 
 
 32 
 
 Lean’s reports 
 
 - 
 
 - 
 
 209 
 
 Double - 
 
 ib. 
 
 Woolf’s Tables 
 
 - 
 
 - 
 
 193 
 
 Useful Receipts - - . 
 
 707 
 
 General observations 
 
 
 . 
 
 212 
 
 
 
 Steel manufacture - 
 
 - 
 
 - 
 
 340 
 
 Varnish, amber, with essence 
 
 
 Converting furnace 
 
 - 
 
 - 
 
 343 
 
 of turpentine - - - 
 
 714 
 
 Steel, cast 
 
 - 
 
 - 
 
 770 
 
 Black - . . - 
 
 732 
 
 to convert iron into 
 
 _ 
 
 - 
 
 769 
 
 For old straw or chip hats 
 
 749 
 
 to colour it blue - 
 
 . 
 
 . 
 
 771 
 
 Blue 
 
 732 
 
 to distinguish it from iron 
 
 
 ib. 
 
 Brick-red - - - - 
 
 ih. 
 
 to gild - - - 
 
 - 
 
 - 
 
 724 
 
 Camphorated mastic, for paint- 
 
 
 Edge tools of cast steel 
 
 and 
 
 
 ings 
 
 743 
 
 iron . - - 
 
 - 
 
 _ 
 
 771 
 
 Caoutchouc - - - 
 
 7SS 
 
 Hardening of 
 
 - 
 
 . 
 
 769 
 
 Chamois colour - - - 
 
 732 
 
 
 
 
 3 
 
 F 
 
 
INDEX, 
 
 7^4 
 
 Varnish Page. Varnish Page. 
 
 Coloured composition for len- Which resists the action of 
 
 deriiig linen and cloth impe- 
 
 
 boiling water - - - 
 
 749 
 
 netrable - 
 
 - 
 
 752 
 
 To make liquid paste with 
 
 
 Coloured, for violins 
 
 - 
 
 745 
 
 drying oil - 
 
 753 
 
 Common f wax, or varnished 
 
 
 To prepare fine printed var- 
 
 
 cloth - - - - 
 
 - 
 
 752 
 
 nished cloth - - _ 
 
 ib. 
 
 Compound mastic 
 
 _ 
 
 742 
 
 To prepare varnished silk 
 
 754 
 
 Copal, camphorated 
 
 - 
 
 739 
 
 To polish - 
 
 755 
 
 Colourless 
 
 - 
 
 738 
 
 To recover - - - - 
 
 ib. 
 
 Ethereal - 
 
 . 
 
 740 
 
 Vertical wind-mills, vide Wind- 
 
 
 Fat amber, or - 
 
 - 
 
 742 
 
 mills 
 
 
 Fat . - - - 
 
 - 
 
 737 
 
 
 
 Gold coloured - 
 
 _ 
 
 738 
 
 Watch - - - - - 
 
 500 
 
 Turpentine 
 
 - 
 
 740 
 
 Table of trains - - * 
 
 504 
 
 White - 
 
 - 
 
 731 
 
 Escapement - 
 
 185 
 
 Fat amber - 
 
 - 
 
 741 
 
 Watch-cases, imitation of tor- 
 
 
 Fat, of a gold colour - 
 
 - 
 
 746 
 
 toise shell - - - - 
 
 738 
 
 Fat turpentine, or golden 
 
 
 ib. 
 
 W’ater-wbecl, breast 
 
 87 
 
 Flaxen grey - - - 
 
 - 
 
 732 
 
 in which the water runs over 
 
 
 Gallipot _ - - 
 
 - 
 
 747 
 
 the shuttle _ . - 
 
 89 
 
 Mastic 
 
 . 
 
 748 
 
 * with two sliuttlcs 
 
 90 
 
 Green . - - - 
 
 - 
 
 732 
 
 by Lloyd and Ostel 
 
 89 
 
 Mordants _ - . 
 
 - 
 
 748 
 
 Overshot - _ . - 
 
 75 
 
 for gilding 
 
 - 
 
 ibl 
 
 with 40 buckets 
 
 ib. 
 
 Pearl grey * 
 
 - 
 
 732 
 
 Smeaton’s experiments on 
 
 79 
 
 Purple - 
 
 . 
 
 ib. 
 
 by Burns _ _ « 
 
 84 
 
 Red - - - . 
 
 - 
 
 ■ib. 
 
 Chain of buckets 
 
 86 
 
 Red Brick 
 
 - 
 
 ib. 
 
 Cliain pump reversed 
 
 ib. 
 
 Resinous drying oil 
 
 - 
 
 737 
 
 Method of laying on water 
 
 
 Sajidarac - - _ 
 
 - 
 
 743 
 
 by Nonaille 
 
 Ill 
 
 Compound 
 
 - 
 
 744 
 
 as practised in Yorkshire - 
 
 112 
 
 Spirituous 
 
 - 
 
 ib. 
 
 Undershot - - - 
 
 65 
 
 Turner's, for box- wood 
 
 - 
 
 746 
 
 Smeaton’s experiments on 
 
 67 
 
 Violet - - _ - 
 
 _ 
 
 732 
 
 by Lambert - - - 
 
 72 
 
 Yellow 
 
 - 
 
 ib. 
 
 Method of constructing by 
 
 
 For balloons 
 
 
 750 
 
 Ferguson _ - . 
 
 114 
 
 ditto - _ - 
 
 
 751 
 
 Brewster _ - - 
 
 117 
 
 Coloured drawings - 
 
 - 
 
 749 
 
 Barker’s mill - _ - 
 
 92 
 
 Drawings and cardwork 
 
 - 
 
 750 
 
 Mill courses _ - - 
 
 105 
 
 Dressing-boxes 
 
 - 
 
 747 
 
 Penstock by Quayle 
 
 109 
 
 Glass . _ - 
 
 - 
 
 750 
 
 Pen trough by Snieaton 
 
 110 
 
 Harps and Dulcimers 
 
 - 
 
 ib. 
 
 Sluice governor - - - 
 
 313 
 
 Indian shields - 
 
 - 
 
 735 
 
 Tide-mills - 
 
 94 
 
 Pales and coarse »wood 
 
 - 
 
 749 
 
 Water-courses and dams 
 
 107 
 
 Silks, &c. 
 
 - 
 
 734 
 
 Wheel-race and water-course 
 
 104 
 
 Unihrelias 
 
 - 
 
 ify. 
 
 Treatises on mill-work 
 
 120 
 
 Violins _ _ - 
 
 - 
 
 732 
 
 Water-spinning - - - 
 
 386 
 
 Ditto - - - 
 
 - 
 
 745 
 
 Reel 
 
 587 
 
 Watch-cases 
 
 - 
 
 738 
 
 Spinning frame - - - 
 
 ib. 
 
 'I’o dissolve elastic gnin 
 
 
 732 
 
 Throstle - 
 
 ib. 
 
 To give a drying quality to fat 
 
 
 Weaving » _ - - 
 
 410 
 
 oils - _ - 
 
 - 
 
 735 
 
 Common Fabric - - - 
 
 411 
 
 to poppy oil 
 
 - 
 
 736 
 
 Common loom _ - - 
 
 •412 
 
 To make painters’ cream 
 
 - 
 
 743 
 
 Dimity or kerseymere 
 
 ib. 
 
 lo paint sail-cloth, so as to be 
 
 
 Double cloth _ - - 
 
 ib. 
 
 pliant, durable, and imper- 
 
 
 Power looms - - - 
 
 413 
 
 vions to water 
 
 - 
 
 751 
 
 Tw celed pattern 
 
 412 
 
 To thicken liiicii=ciolh 
 
 for 
 
 
 Wedge - - - - - 
 
 1.3 
 
 screens 
 
 - 
 
 755 
 
 Combinations of (lie 
 
 IS 
 
Page. 
 
 Page. 
 
 Wheels, wheel aud trnndel - 24 
 
 Wheel and pinion - - ib. 
 
 Leader and follower - - 2.5 
 
 Which combine the advan- 
 
 tages of the pinion and trundle 26 
 Wheel and axle - _ - lO 
 
 combinations of the - - l6 
 
 White metal - . - - 710 
 
 Wind-mill, vertical, Post-mill - 122 
 Smock-mill - 123 
 
 .Smeaton's experiments on - 125 
 
 Sails, rules for modelling 123 
 by Hall Gower - - 129 
 
 by Baines - _ - 132 
 
 Clothing and unclothing 
 while in motion - - 130 
 
 Wind-mill 
 
 Equalizing the motion of 
 Mill with 8 quadrangular sails 
 Horizontal - - - - 
 
 Wire manufacture 
 
 Draw-bench - - - 
 
 Draw-plates - 
 
 Ditto - - - _ - 
 
 Hand machine - 
 
 for musical instruments 
 Mouchel’s manufactory 
 Wollaston’s experiments 
 W''i'itings, drawings, &c., to gild 
 
 Yellow gold, to heighten the 
 colour of - - - 
 
 153 
 
 135 
 
 139 
 
 344 
 
 345 
 
 348 
 
 354. 
 
 346 
 
 347 
 
 349 
 356 
 721 
 
 724 
 
DIRECTIONS TO THE BINDER. 
 
 Plate 1 
 
 to face Page 2 
 
 2 
 
 12 
 
 3 
 
 22 
 
 4 
 
 26 
 
 5 
 
 30 
 
 ' 6 
 
 36 
 
 • 7 
 
 62 
 
 8 
 
 74 
 
 9 
 
 86 
 
 10 
 
 94 
 
 11 
 
 112 
 
 12 
 
 124 
 
 13 
 
 130 
 
 14 
 
 134 
 
 15 
 
 
 ]() 
 
 142 
 
 17 
 
 148 
 
 18 
 
 162 
 
 19 
 
 168 
 
 20 
 
 
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 178 
 
 22 
 
 184 
 
 23 
 
 
 24 
 
 
 25 
 
 215 
 
 26 
 
 230 
 
 27 
 
 
 28 
 
 248 
 
 29 
 
 
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 31 
 
 264 
 
 32 
 
 
 o o 
 Oi> 
 
 272 
 
 34 
 
 276 
 
 35 
 
 282 
 
 36 
 
 900 
 
 36* 
 
 
 37 
 
 300 
 
 38 
 
 
 39 
 
 308 
 
 40 
 
 310 
 
 41 
 
 
 42 
 
 
 43 
 
 322 
 
 44 
 
 324 
 
 45 
 
 
 46 
 
 
 Plate 47 to face Page 334 
 
 48 336 
 
 49 346 
 
 50, 51, 52 366 
 
 53 370 
 
 54 374 
 
 55 380 
 
 56 382 
 
 57 390 
 
 58 412 
 
 60 ^96 
 
 61 402 
 
 62 404 
 
 63 406 
 
 64 442 
 
 65 446 
 
 66 448 
 
 , *67 68 424 
 
 69 426 
 
 70 434 
 
 71 440 
 
 72 486 
 
 73 488 
 
 74 492 
 
 75 500 
 
 76 512 
 
 77 516 
 
 ■77* 520 
 
 78 540 
 
 79 542 
 
 80 562 
 
 81 ... r.. 568 
 
 82 570 
 
 83 574 
 
 84 576 
 
 85 590 
 
 86 592 
 
 87 598 
 
 88 602 
 
 89 674 
 
 90 682 
 
 91 686 
 
 92 690 
 
 93 648 
 
 94 650 
 
 95 668 
 
 X.B. The author would advise such of the purchasers as intend to 
 have the work bound, to have the plates put in a separate volume, 
 
 * 67, 68, must be guarded . 
 

 : *r 
 
 
 / ‘ 
 
 
 % 
 
 
 
 .. if, 
 
 -f 
 
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