Back of 
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Back of 
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!PlSS(SaSlI2 
 
 CIRCULAR TURNING^ 
 
 WITH 
 
 ^practical instructions, 
 
 FOR 
 
 PRODUCING CORRESPONDING 
 PIECES IN THE ART. 
 
 ''MiiWcJl l Z trated b , V C °PP er -P late Engravings, and 
 '$/§Sjr CuU re f trnn g to and explaining the different Ji<r m 
 _ to be executed. 
 
 Bv JOHN HOLT IBBETSON, Esq' 
 lEOtttoir, 
 
 With considerable Additions, including a des 
 { cription and copper-plate engravings of the ' 
 
 Compound Eccentric Chuck constructed 
 by the Author, and used by him in the 
 execution of his Specimens. 
 
 LONDON: ^ 
 
 LONGMAN, ORME, BROWN, GREEN AND LONfW^? 
 
 WEALE, HIGH HOLBORN; LAYTON, FLEET sSet^ 
 
 k 
 
11 
 
 INTRODUCTION. 
 
 that Instrument would form, in all pro¬ 
 bability, a part of the apparatus of most 
 Amateur Turners. 
 
 At the time the Second Edition was 
 going to be printed, the Publisher was 
 very desirous that it should contain a de¬ 
 scription of the Machinery by which the 
 Specimens might be executed, as he was 
 of opinion that the sale of the book 
 would thereby be much improved; and I 
 so far yielded to his wishes as to give my 
 consent to his publishing a description of 
 an Eccentric Chuck and Slide Rest, pro¬ 
 vided it was explained that they were not 
 the Instruments (nor similar in construc¬ 
 tion to them) which I had, myself, used 
 in executing the Engravings. The second 
 Edition, therefore, gave the same Speci¬ 
 mens which had appeared in the first, to¬ 
 gether with a description of an Eccentric 
 
INTRODUCTION. iii 
 
 Chuck and Slide Rest by means of which 
 they could be executed. 
 
 In the present, which is the Third Edi¬ 
 tion, the description of the Chuck and 
 Slide Rest that appeared in the Second 
 Edition, is left out; and, in lieu thereof, 
 
 I shall give a description of the identical 
 Slide Rest and Chuck with which all the 
 Specimens I have ever worked out in pure 
 Simple and Compound Eccentric Turn¬ 
 ing, were actually executed and engraved; 
 and in giving this description I shall 
 pursue the following plan. 
 
 In the first place I will give a descrip¬ 
 tion of the Slide Rest. 
 
 In the second place I will give some 
 explanation of the origin of the Chuck, 
 and of the causes which induced me to 
 undertake the manufacture of it with my 
 own hands; and I shall also remark on 
 
IV 
 
 INTRODUCTION. 
 
 such parts of it as I consider new in their 
 application to such machinery. 
 
 In the third place I will give a full 
 description of the Chuck, with reference 
 to the copper plate Engravings which are 
 inserted in front of the title page. 
 
 In the fourth place, every thing that 
 appeared in the first Edition will be re¬ 
 printed in this Edition ; and 
 
 In the fifth place I will give some Spe¬ 
 cimens illustrative of the powers of the 
 Chuck which I contrived and constructed 
 myself and have denominated Ibbetson’s 
 Improved Compound Eccentric Chuck, 
 with practical instructions for producing 
 some of the Figures. 
 
THE SLIDE REST. 
 
 A t the bottom of Plate 1, Fig. 2, a per¬ 
 spective view is given of the Slide Rest 
 I have always used, never having posses¬ 
 sed any other: it is very simple and com¬ 
 pact in its construction; and, as far as 
 regards Eccentric Turning, is a complete 
 and effective instrument. It is of the 
 construction of Messrs. Holtzapffel, of 
 whom I purchased it many years ago, and 
 by their permission I have introduced the 
 engraving and give a description of it. 
 In the course, however, of the long period 
 I have possessed it, they have made many 
 improvements and additions to their Slide 
 Rests, as might reasonably be expected, 
 and have greatly amplified their power 
 of action. 
 
6 
 
 The stand of the Slide Rest (shewn at 
 A. A.) fastens to the Lathe Bed by a 
 screw, in the usual manner. B. B. is 
 attached to this stand by a stem passing 
 into the projecting boss, and by the screw 
 a. in the side of the boss, the stem is 
 clamped fast, so that B. B. shall stand at 
 the required height from the Lathe Bed 
 and at any angular position with respect 
 to the Mandril. C. C. slides from end 
 to end on B. B. and is moved and held 
 fast in its required place by the Slide 
 Rest screw (not seen in the engraving), 
 which is moved by its handle b. D. D. 
 slides, backwards and forwards, in the 
 piece C. C. at right angles with B. B. 
 The tool to be worked with, fits into the 
 socket e. e. and the square-headed screw 
 at the top of e. e. clamps and holds the 
 tool fast. At the end of the slide D. D. 
 there are two adjusting screws d, d which 
 regulate the depth and limit the cut of 
 the tool. 
 
 The cutting edges of the tools are 
 
7 
 
 ground up to various shapes—angular, 
 square, and rounding, &c. according to 
 the taste and fancy of the workman. In 
 turning down the surface of the ivory or 
 wood that is to be ornamented, I gene¬ 
 rally make use of a tool with a rounding 
 edge, which I sharpen on a stone by hand; 
 but to grind and sharpen the angular and 
 square, or flat cutting tools, I use a tool 
 made by Messrs. Holtzapffel, by which 
 any desired angle is obtained to a cer¬ 
 tainty. This contrivance for setting the 
 angular tools is. highly convenient, if not 
 absolutely necessary, as it enables the 
 workman to sharpen the tool as often as 
 he pleases, during the progress of a piece 
 of Turning, which, without it, or some 
 contrivance of the sort, it would not be 
 prudent in him to attempt, for fear of 
 altering the angle of the tool, and there¬ 
 by spoil the work. 
 
8 
 
 THE CHUCK. 
 
 X do not wish it to be supposed that I 
 take to myself the credit of being the in¬ 
 ventor of Compound Eccentric Chucks. 
 Instruments, constructed on various plans, 
 have appeared before the Public under 
 that name—there is a description of one 
 in the Manuel du Tourneur—and Messrs. 
 Holtzapffel, and other manufacturers, 
 have constructed them for a length of 
 period. The one which I describe in 
 the present Edition, happens however 
 to differ essentially, in its construction, 
 from those which have hitherto become 
 known; and I offer it to attention as 
 possessing far greater powers. It is the 
 result of the perseverance and labour 
 of a self-taught Amateur Mechanic and 
 
9 
 
 Turner, having been contrived and con¬ 
 structed by myself many years ago, from 
 the raw materials of brass and steel, with 
 my own hands; and I present it as an 
 instrument to which I have never given 
 publicity, excepting having shewn it and 
 explained it to two or three friends. Had 
 I not proved able to make it myself, my 
 plan of its construction would never have 
 been realized; and I, certainly, should 
 not have had the means of producing 
 the Compound Eccentric work which is 
 exhibited in this Edition. 
 
 Six-and-thirty years ago I purchased 
 a Lathe and commenced Turning as an 
 amusement; and I very soon saw that 
 the Art of Turning might be greatly ex¬ 
 tended by various little contrivances to 
 be appended to the Lathe and Slide Rest, 
 and by the construction of Chucks : but 
 I found, at the same time, that one of the 
 greatest difficulties that opposed the pur¬ 
 suits of the Amateur Mechanic, was his 
 not knowing how or where to get his 
 
10 
 
 projects carried into practical effect. I 
 invariably found that the professional 
 Mechanic, in the habit of constructing 
 Machinery, considered it too great an in¬ 
 terference with his own business to trou¬ 
 ble himself with the projects of an Ama¬ 
 teur: in fact, I saw plainly, that, to car¬ 
 ry my plan of an Eccentric Chuck into 
 practice, without being cramped or foiled 
 in my views, it was absolutely necessary 
 for me to become my own workman ; and 
 I, therefore, took resolution and resorted 
 to my own exertions and actual manual 
 labour. I had, moreover, a strong mo¬ 
 tive for going into the labour of making 
 the Chuck myself, in a wish to keep the 
 mechanism of it secret; and this I full 
 well knew I should have no chance of 
 doing, if the Chuck were manufactured 
 by any other hands than my own: 1, in 
 fact, constructed the Chuck in aid of a 
 plan 1 had conceived for rendering Bank 
 Notes more difficult of imitation. 
 
 I most cordially wish that every Ama- 
 
11 
 
 tern* Turner would make known, where 
 there is no object for secrecy, in some 
 way or other, whatever might occur to 
 him as being a novelty in the Art; it 
 would prove a source of amusement to 4 
 himself and of information to others. If 
 he only gave specimens of the result of 
 his labours, without communicating the 
 particulars of his machinery, he would 
 give a great stimulus to exertion in the 
 Art of Ornamental Turning. Besides, 
 there are facilities now open to the Ama¬ 
 teur, for carrying his projects into prac¬ 
 tical effect, which did not formerly exist. 
 
 There is no longer any occasion for him 
 to be his own workman (unless secrecy be 
 desired)—he can readily get any thing 
 executed for him, let it be ever so extend¬ 
 ed in its mechanism, or of ever so trifling 
 a nature. If he wants a casting in brass 
 or metal, or a piece of steel forged, or a 
 mere screw made, he is able, without any 
 sort of difficulty, to get it done at Messrs. 
 Holtzapffel’s manufactory. This is, un- 
 
12 
 
 questionably, a very great practical con¬ 
 venience.—I find it so, and, now, conti¬ 
 nually avail myself of it. 
 
 My Compound Eccentric Chuck, as I 
 now use it, and as it is represented by 
 the Copper Plate Engravings inserted 
 against the title page, has been altered 
 to its present state since I executed the 
 Specimens which were exhibited in the 
 First Edition. The alterations I have 
 introduced, considerably simplify its con¬ 
 struction, and, at the same time, give it 
 a power of adjustment and of produc¬ 
 ing some patterns which it did not be¬ 
 fore possess, and which I had never con¬ 
 templated as coming within the range of 
 the capabilities of any Eccentric Chuck, 
 however extended its mechanism might 
 be. I, however, profess to give a full de¬ 
 scription of my Chuck, as I used it in ex¬ 
 ecuting all the Specimens; and therefore, 
 before I enter into a general description of 
 it, in its present state, I will explain the 
 particulars of the alterations I allude to. 
 
13 
 
 On referring to Plate Fig. 1, the two 
 circular moving pieces are seen with their 
 appertaining circles divided into 96, and 
 toothed wheels attached, each cut into 96 
 teeth, to be acted upon bj a click. When 
 the Specimens which appeared in the First 
 Edition were executed, these two circu¬ 
 lar moving pieces were divided different¬ 
 ly—the edge of the one next the Lathe 
 head (marked L. Plate 1.) was racked on 
 its edge , so as to be worked by a tangent 
 screw, into 288 divisions,—whilst the 
 edge of the other circular moving piece 
 which is attached to the second Bed 
 Plate was cut into 96 teeth and acted 
 upon by a click. The tangent screw 
 which acted on the racked edge, then in 
 the place of L, was fixed in a frame, in 
 the same manner as the screw d. d. in 
 Fig. 1. The frame was moveable at one 
 end as a centre, and at the other end 
 there was a catch which kept the tangent 
 screw fast to the racked edge of the cir¬ 
 cle, or detached from that edge, at plea- 
 
14 
 
 sure. The tangent screw was, therefore, 
 susceptible of being employed as a click; 
 at the same time, by turning the screw 
 round, the circle could be stopped at 
 every possible point; and a ring of brass, 
 fixed on the head of the tangent screw, 
 was decimally divided into a hundred 
 parts, so that the power of division was 
 very great. The tangent screw acting 
 on a racked edge is by far the most com¬ 
 plete of the two methods adverted to; 
 but there are practical difficulties and 
 mechanical labour attending its execu¬ 
 tion, which induced me to adopt the 
 click and toothed wheel system—and I 
 also found that the number 288, into 
 which the circle was racked, did not ac¬ 
 cord, in point of angular adjustment, 
 with the number 96, which was the num¬ 
 ber of teeth in the toothed wheel. The al¬ 
 teration I mentioned consisted, therefore, 
 in making the two circular moving pieces 
 alike in all respects, with a division of the 
 edge into 96 teeth, to be worked by a 
 
15 
 
 Click. With the machinery I possess, I 
 find, however, no difficulty in racking 
 the edge of a circle into any number that 
 is divisible by some other number: I 
 lately racked one into Two hundred and 
 seventy-two. divisions, which is rather a 
 curious number, being divisible by 136, 
 68, 34, and 17. 
 
 I will now enter into some preliminary 
 explanation of a few of the results which 
 flow from the combined adjustments of 
 the two circular moving pieces I have 
 just adverted to, and of which the addi¬ 
 tional Specimens will furnish some prac¬ 
 tical examples. I consider them ex¬ 
 tremely curious; and I think I may ven¬ 
 ture to pronounce them, without fear of 
 contradiction, as being completely novel 
 in the Art of Eccentric Circular Turning. 
 
 The engraving. Fig. 5, gives a plan of 
 the Bed Plate and Slide Plate of the 
 Chuck; and the circular moving pieces, 
 just mentioned, are affixed to the Slide 
 Plates G. G. in the centre, as represented 
 
16 
 
 at G. G, where there are two circular 
 lines described. By means of the Slide 
 Plates, therefore, the two circular mov¬ 
 ing pieces may be placed eccentric to 
 each other, and to the Mandril’s motion. 
 Now, suppose it be required to place 96 
 circles or dots,* consecutively, in the 
 curve of an Ellipsis, the transverse dia¬ 
 meter of which shall be three inches, and 
 the conjugate diameter two inches. The 
 method by which it is to be accom¬ 
 plished with the Compound Eccentric 
 Chuck is as follows:—Adjust and fix the 
 describing point, or cutting tool, so as to 
 cause its point to coincide with the cen¬ 
 tre of the Mandril’s motion, if it be in- 
 
 * The diameter of the circles is determined by 
 the position of the describing point, or cutting tool 
 which is fixed in the Slide Rest. If the point or 
 tool be adjusted to coincide with the centre of the 
 Mandril’s motion it will describe a dot, if it be ad¬ 
 justed to the left of the centre of the Mandril it 
 will describe a circle, the radius of which will be 
 equal to the distance between the point of the tool 
 and centre of the Mandril. 
 
17 
 
 tended to describe a dot, or at a distance 
 from the centre of the Mandril equal to 
 the radius of the required circle. Then 
 move the Slide Plate next the Lathe 
 head (G. G. Fig. 5.) by turning the 
 screw ( d . d. Fig. 1,) \ of an inch from its 
 central position, and the other Slide 
 Plate 1^ inch. Set the circular moving 
 pieces so that the index points to divi¬ 
 sion 96 on both.—Turn the Lathe round, 
 and cause the fixed tool to describe the 
 dot or circle. The circular moving piece, 
 next the Lathe head, is then to be moved 
 two divisions, making the index point 
 to division 2; and the other circular 
 moving piece is to be moved one divi¬ 
 sion, in the contrary direction, making 
 its index point to division 95. Another 
 circle or dot is then to be described. The 
 first circular movement is again to be 
 moved two divisions, which will place the 
 index at division 4. The other circular 
 movement is to be moved one division, 
 in the contrary direction, which will 
 
 c 
 
18 
 
 bring its index to point to division 94, 
 and describe a dot or point as before. 
 The circular movements are to be moved 
 and adjusted, in this way, until the figure 
 be completed: the circular movement 
 next the Lathe head is to be moved two 
 divisions at a time, in its direction, whilst 
 the other circular movement is to be 
 moved one division each time, in the 
 contrary direction. 
 
 The number of beautiful designs which 
 may be obtained by combining, on this 
 principle, two circular adjusting move¬ 
 ments, is inconceivable. Consecutive cir¬ 
 cles, &c. may be arranged, not only in 
 elliptical curves, but in the shape of 
 hearts—in straight lines—in triangles—in 
 squares—in polygons, and in both inward 
 and outward looped figures. In Ellipti¬ 
 cal figures the ratio of adjustment, be¬ 
 tween the two circular movements, is as 
 two to one, in contrary directions; that 
 is, if the one be moved two divisions each 
 time, the other must be moved one divi- 
 
19 
 
 sion each time, in the contrary direction. 
 If one circular movement be moved four 
 divisions each time, and the other two 
 divisions in the contrary direction, the 
 Elliptical pattern will consist of 48 con¬ 
 secutive circles; if one of them be moved 
 eight divisions and the other four, the 
 number of consecutive circles, in the pat¬ 
 tern, will be 24; and thus the number of 
 the consecutive circles can be always re¬ 
 gulated. With this same ratio of adjust¬ 
 ment of the Slide Plates and of the cir¬ 
 cular movements, the latter being in the 
 same direction, instead of being in con¬ 
 trary directions, the pattern formed will 
 consist of two loops inwards. If the 
 ratio of adjustment, between the two cir¬ 
 cular movements, be equal (that is, if they 
 each be moved the same number of divi¬ 
 sions at every adjustment) and the move¬ 
 ments are made in the same direction, the 
 pattern will be heart-shaped. 
 
 In all figures where the number of an¬ 
 gles or loops are more than two, the loops 
 
20 
 
 will invariably turn outwards when the 
 circular movements are moved in contrary 
 directions, and inwards when they are 
 moved in the same direction. 
 
 Triangles are obtained when the ratio 
 of the circular adjustment is as three to 
 one: and, Squares are obtained by ad¬ 
 justing the circular movements in the 
 ratio of four to one. Figures of six 
 loops are obtained when the ratio of the 
 adjustment of the circular movements is 
 as six to one; and so on for all others. 
 In fact, the adjustment of two circles, 
 in the manner I have described, arranges 
 the circles or dots which compose the 
 pattern, in the curve of an Epicycloid ; 
 and, in conformity with the properties 
 of that curve, the number of loops in¬ 
 evitably depends on the ratio of velocity 
 between the two circular motions. The 
 circles or dots so arranged in the curve 
 of an Epicycloid, will gradually ap¬ 
 proach each other in one or more parts 
 of the pattern, and recede from each 
 
21 
 
 other in other parts; but this inequality 
 of arrangement must not be looked upon 
 as a defect in the Machinery, as, in 
 reality, it results from natural causes in- 
 herent in Epicycloidal motion. A com¬ 
 pensating movement might be introduced 
 into the Chuck that would correct this 
 varying principle—I have applied it to 
 other apparatus, and, at one time, in¬ 
 tended to add it to the Compound Ec¬ 
 centric Chuck, but I have never done so. 
 
22 
 
 THE ENGRAVINGS. 
 
 I will now give a description of the 
 mechanical contrivance of the Chuck 
 which I have denominated “ Ibbetson’s 
 Improved Compound Eccentric Chuck,” 
 and in the course of explaining the cop¬ 
 per-plate Engravings of it, inserted in 
 front of the title-page, I shall particu¬ 
 larly take notice of those parts which I 
 consider to be new, and that give results 
 which have not hitherto been looked up¬ 
 on as coming within the range of Eccen¬ 
 tric Turning. 
 
 I would not have it supposed to be 
 my intention to offer instruction to the 
 professional Mechanic, on matters which 
 he may, probably, be already fully ac¬ 
 quainted with. I consider that I am 
 
23 
 
 addressing the Amateur who may know 
 little or nothing about the mechanism of 
 an Eccentric Chuck ; and, therefore, if I 
 am more diffuse in my description than 
 by some may be thought necessary, and 
 enumerate things that have been, over 
 and over again, employed in the con¬ 
 struction of Machinery, I will still hope 
 to stand excused; and I beg to be per¬ 
 fectly understood as not taking credit 
 for invention, in any instance, beyond 
 what I shall specially lay claim to. 
 
 Figure 1 gives a side view of the 
 Chuck in its real dimensions, and as it 
 appears when screwed on the Lathe. 
 
 Figure 5 gives a Plan of the Bed 
 Plates and Slide Plates of the Chuck; 
 and. 
 
 Figure 3 gives a Section shewing the 
 internal construction of the circular 
 movements of the Chuck. 
 
 In figure 1 the piece A. B. B. is the 
 Bed Plate of the Chuck next the Lathe- 
 head, and, with the projecting piece D, 
 
24 
 
 is formed out of one casting of brass or 
 metal. This Bed Plate screws on the 
 nose of the mandril at its projecting part 
 A. and carries the whole of the remain¬ 
 ing parts of the Chuck. The projecting 
 piece f. at the end of the Bed Plate op¬ 
 posite to D. is kept to its place bj steady 
 pins, and is attached to the Bed Plate by 
 two screws, one of which is seen just un¬ 
 der/.* 
 
 The Cut hereunder inserted is a section 
 of the piece f as it would appear across 
 the Bed Plate. 
 
 This piece 1. 1. 1. is made out of brass, 
 separate from the Bed Plate, but attach¬ 
 ed to it by the two screws 2. 2. and kept 
 
 * It is to be understood that what is said with 
 regard to this Bed Plate and its appendages, next 
 the Lathe-head, applies also to the other Bed Plate 
 and its appendages. 
 
25 
 
 firm to its place by the steady pins 3 3. 
 These steady pins can only enter into the 
 Bed Plate a very little way, as shewn in 
 the cut, on account of the screw d. d, one 
 end of which passes through the hole at 4. 
 This piece/, (shewn at f. in fig. 1.) must 
 be fixed in its place on the Bed Plate be¬ 
 fore the hole at 4. is drilled ; which hole, 
 and also the screw hole through the piece 
 D, must be both drilled at the same time, 
 in the manner hereinafter explained. 
 
 In figure 5, B. B. gives the outline of 
 the Bed Plate, at one end of which is 
 seen a portion of the screw d. d. fig. 1. 
 G. G. figure 1. gives the outline of the 
 Slide Plate, which it will be perceived is 
 not so long as the Bed Plate, thereby giv¬ 
 ing more scope for eccentric adjustment. 
 In fig. 5, E. E. is one steel arm and F. F. 
 the other, between which the Slide Plate 
 traverses. The two circular lines, in the 
 centre, shew the hole through which the 
 screw N. (fig. 3) passes; and the large 
 circle represents the outline of the screw 
 
26 
 
 nut k. k. fig. 3 L. fig. 5, is a portion 
 of the toothed wheel which forms part 
 of the circular movement, and 5. 4. is the 
 click which stops the toothed wheel at 
 any required division of the circle. In 
 the Bed Plate B. B. (see figures 1 and 5, 
 and Boss A. fig. 1.) there is a long open¬ 
 ing, c. c. fig. 5, represented by dots, and 
 by dots at Boss A. fig. 1, which gives pas¬ 
 sage to the plug and screw ring through 
 which the screw d. d. acts, see fig. 4. E. 
 E. and F. F. fig. 5, are steel arms with 
 angular edges, which take into the dove¬ 
 tailed edges of the Slide Plate G. G. The 
 steel arm E. E. is retained in its position 
 by two steady pins, represented by dots, 
 and screwed fast to the Bed Plate by two 
 screws. The steel arm F. F. is kept fast 
 to the Bed Plate by two screws, and the 
 holes in it, through which the screws 
 pass, are elongated (as seen by dots), in 
 order to meet the action of the clamp 
 serews i. i. The Slide Plate G. G. tra¬ 
 verses, parallel to the Bed Plate, between 
 
27 
 
 the two steel arms E. E. F. F.; and the 
 screws i. i. which screw into the edge 
 of the Bed Plate, are adjusting screws 
 to press the steel arm into the grooved 
 edge of the Slide Plate, so as to cause 
 the Slide Plate to traverse with the pro¬ 
 per degree of tightness. The screw d. d. 
 (seen in fig. 1.) is the Slide Plate screw, 
 and by the action of it the circular 
 movements, which the Slide Plates carry, 
 (hereafter described) become fixed at any 
 required position eccentric to the man¬ 
 dril. This screw is retained in its place in 
 a different manner to any I have usually 
 seen employed in similar cases, and is so 
 secured that nothing like what is called 
 loss of time can possibly occur; and in 
 every application of a screw, fitted as this 
 is, I have found its action most efficient. 
 One end of this screw has a countersunk 
 conical hole drilled in it, to receive the 
 point of the screw which screws tightly 
 through the piece D. The other end 
 passes through, and correctly fits, a round 
 
28 
 
 hole in the piece /. (see 4. in the cut in 
 page 24,) and the screw at D. presses 
 the shoulder of the screw d. d. into close 
 contact with the side face of the piece 
 f. The part of the end of the screw 
 which passes beyond the piece f. is left 
 with a small shoulder flush with the face 
 of the piece. A ring of brass (the ring 
 seen a if with division lines) fits up to 
 this shoulder, and is kept firm to it by 
 a milled-head screw; and the end of the 
 screw, beyond the screw nut, is squared, 
 in order to its being moved round by a 
 kev. I divide this brass ring into one hun¬ 
 dred, of which, four grand divisions are 
 distinguished by 0, 1, 2, 3; and this ring 
 is made to move round against the said 
 shoulder, in order that 0. may, under 
 any circumstance that may arise, be ad¬ 
 justed to the line serving as an index on 
 the top of f The piece /. is also neces¬ 
 sarily detachable from the Bed Plate, to 
 make way for the screw d. d. being placed 
 in its proper situation for action. 
 
29 
 
 The Click seen at 4. 5. figure 5. is, I 
 consider, an entirely new contrivance of 
 my own invention, and I call it A double 
 acting Micrometer Click. This double 
 acting micrometer Click, has never been, 
 however, actually applied to my Com¬ 
 pound Eccentric Chuck; but having used 
 it in other machinery, and found it to be 
 very efficient in its action, I resolved to 
 give the present edition the advantage of 
 its publication. The drawing of it in 
 fig. 5 was taken, for the engraver, from 
 a rough sketch I had made, wherein a 
 little inaccuracy occurred which I now 
 correct. It will be perceived that for 
 want of room to place the spring (6, fig. 
 5), the screws which affix it to the Slide 
 Plate enter into the grooved edge. This 
 must not be, and I, 
 therefore, suggest 
 the substitution of 
 a spring of a differ¬ 
 ent shape, as here- 
 against shewn. The 
 
30 
 
 Clicks which take into and stop the cen¬ 
 tre wheel, are portions of small wheels, say 
 of wheels of twenty-fo ur teeth. Through 
 the centre of these a screw passes, and 
 attaches them to a plate of brass about 
 an eighth of an inch thick, of any shape, 
 such as is represented by the outline 
 which encloses 4 and 5. This Click 
 piece moves on a centre constructed as 
 follows: 
 
 1. 1. is a piece 
 of steel, with a hole 
 drilled through it, 
 to receive the screw 
 3. (the head is seen 
 at 4. in plate fig. 5.) 
 which attaches it to the Slide Plate. 
 The Click piece is fitted nicely on the 
 shoulder 2. 2. and the screw 3. con¬ 
 fines it so as to let it move round on 
 that shoulder without shake. This steel 
 piece is of such thickness as will place 
 the Clicks in the same plane with the 
 centre toothed wheel, and allow space 
 
Si 
 
 between the Click piece and Slide Plates, 
 for the spring seen at 6, and roller seen 
 at 7. The roller is hardened steel, and 
 the spring, which should be rather a 
 strong one, has a projecting ridge at its 
 end, which acts against the roller. By 
 pressing the end (5.) of the Click piece 
 to either side, the spring will throw the 
 Click, on the same side, into contact 
 with the centre toothed wheel. Each 
 Click has a screw through its centre, 
 which attaches it to the Click piece; 
 and one of them has, also, a screw which 
 passes through an eccentric long opening 
 in it, and clamps it fast to the Click 
 piece in any required angular position. 
 It is expedient that this Click, with the 
 elongated eccentric opening, should be 
 adjusted and clamped in its proper place 
 in the progress of constructing the Chuck, 
 before the circular movement is divided 
 and figured; and I recommend the fol¬ 
 lowing method of proceeding. The 
 Chuck being screwed to the mandril. 
 
32 
 
 the two Slide Plates must be adjusted so 
 that they will traverse on their respective 
 Bed Plates, in a parallel line with each 
 other as near as may be, and the Click 
 with the long opening is then to be 
 placed in contact with the centre toothed 
 wheel. The clamp screw of the Click 
 must be loosened so as to allow the Click 
 to move on its centre screw, it must also 
 be ascertained that the Slide Plates now 
 traverse perfectly in parallel lines to each 
 other: and this point having been proved 
 by two or three trials, the clamp screw 
 in the long opening in the Click must 
 be screwed quite tight, not again to be 
 moved unless by any chance the Click 
 should get out of this—its proper posi¬ 
 tion. The place on the circle to which 
 the index points, should be marked for 
 the place of the prime division, which I 
 shall further notice when I come to the 
 description of the circular movements. 
 I will here mention the method I employ 
 to ascertain that the two Slide Plates tra- 
 
33 
 
 verse in perfect lineal parallelism. The 
 Chuck being screwed on the Mandril, a 
 piece of hard wood is fixed on it, and the 
 surface of the wood is turned down to a 
 plane. A pointed tool is fixed in the 
 Slide Rest, the point touching the wood, 
 and the screw of the Slide Plate, next the 
 Lathe head, being turned, and the Slide 
 Plate being thereby caused to traverse 
 both ways on the Bed Plate, the point 
 of the tool will describe a right line on 
 the piece of wood. This Slide Plate is 
 then to be brought to its central position, 
 and the screw of the other Slide Plate is 
 to cause the wood to move, backwards 
 and forwards, in a right line against the 
 point of the tool. If the point of the 
 tool traces, in the second instance, the 
 same line it delineated in the first, the 
 Slide Plates, as a matter of course, must 
 have traversed in perfect lineal parallel¬ 
 ism. If two lines any where appear, the 
 error must be got rid of by adjusting the 
 circular movement, next the Lathe head , 
 
 D 
 
34 
 
 whilst the clamp screw of the Click is 
 loose, as before mentioned. 
 
 The Click, at the other side of the 
 Click piece, which has only a screw 
 through its centre, is to be resorted to 
 whenever an adjustment of the circular 
 movement is required that cannot be ob¬ 
 tained by the other Click alone. Sup¬ 
 pose, for instance, a division of 192 be 
 required, it cannot be obtained by one of 
 the Clicks alone, but by the action of 
 the two Clicks, conjointly, it can. The 
 screw in the centre of the Click must be 
 loosened, so that the Click will move on 
 its centre, and the Click is to be brought 
 into contact with the toothed wheel of 
 the centre movement. The toothed cen¬ 
 tre wheel must now be moved, so as to 
 cause the index to point exactly half way 
 between any two of the divisions of 96, 
 and then the screw in the centre of 
 the Click is to be screwed fast. In this 
 state of the Clicks, if they be brought, 
 alternately, into contact with the toothed 
 
35 
 
 wheel, the centre movement will be 
 moved only half a tooth at each adjust¬ 
 ment, and thus a division of 192 will be 
 obtained; and it is evident, that, by 
 altering the angular position of this 
 Click, the centre circular movement may 
 be stopped at every possible point; and 
 this Click is, therefore, most truly speak¬ 
 ing, A Micrometer adjusting Click. 
 
 T have before mentioned that I had 
 judged it expedient to remove the tangent 
 screw and racked edge circle from my 
 Chuck, and to substitute a click and 
 toothed wheel. When, however, I de¬ 
 cided upon doing this, I found that the 
 common kind of click would not answer 
 my purpose—that it was necessary to em¬ 
 ploy one that would adjust to any minute 
 portion of a tooth of the wheel; and 
 it was, therefore, on this occasion that I 
 first contrived the click which I here give 
 a plan of, and which I have denominated 
 The Single micrometer adjusting Click; 
 and this Click I now employ, in the Chuck 
 
36 
 
 I work with, on the circular movement 
 which is between the two Slide Plates, 
 instead of the Double acting Click des¬ 
 cribed at page 29. The adjustment of it 
 is the same as that of the Click with the 
 long opening (4, 5, fig. 5,) which has been 
 already explained, and the necessity of 
 using such a Click will be obvious when 
 it is considered how very difficult it would 
 be with the common Click to set the 
 Slide Plates in perfect lineal parallelism. 
 Without the power of parallel adjust¬ 
 ment of the Slide Plates, and of retaining 
 them in that position by means of the 
 action of the Click on the toothed wheel, 
 the Chuck would be very defective in its 
 work: if they cannot be set parallel, they 
 cannot be set at right angles, or at any 
 other angle required; and thus squares, 
 and triangles, and polygons, could not be 
 correctly accomplished—indeed, there are 
 so many figures and beautiful patterns 
 that depend upon the correct angular ad¬ 
 justment of the Slide Plates, that a micro- 
 
37 
 
 meter adjusting Click, or something that 
 will answer the same purpose, is actually 
 indispensable. 
 
 The division, on the divided circle of 
 the circular movement, to which the 
 index points when the Slide Plates are 
 in lineal parallel position, and which 
 division I have, in another place, called 
 the prime division, is to have the num¬ 
 ber 12 engraved over it. I have now, in 
 the course of long practice, adopted and 
 used, on various occasions, the simple and 
 plain notation of the divisions of a circle 
 which is shewn in fig. 1. The toothed 
 wheel consists of 96 teeth, and every 
 eighth tooth is distinguished, consecu¬ 
 tively, by the numerals 1, 2, 3, 4, 5, 6, 7, 
 8, 9, 10, 11, 12. In the Plate there is 
 only a divisional line to every two teeth, 
 but, with reference to the Micrometer 
 Click, before spoken of, I recommend 
 that a divisional line be placed for every 
 tooth in the wheel, and that the space of 
 one tooth, say, the one next to division 
 
38 
 
 12, shall be divided in half—that the 
 space next to that be divided into three 
 parts—and the next space into four parts, 
 and I give a cut hereunder to explain 
 exactly what I mean; and this engraving 
 I executed by means of my Compound 
 Chuck. 
 
 Practice has taught me that the fewer 
 the figures, the less frequently will mis¬ 
 takes arise, and the less puzzling will be 
 the adjustment of the circular move¬ 
 ments. 
 
 The scale on the edge of the Bed 
 Plates (see Plate I, fig. 1, at B. B.) should 
 be so divided that every turn of the Slide 
 Plate screw shall cause the index to point 
 to a divisional line; the grand divisions 
 are to be distinguished by a numeral, and 
 each of them is to contain ten of the 
 smaller divisions; and, when the circular 
 movements (see K. K.) are in the middle 
 
39 
 
 of their respective Bed Plates and con¬ 
 centric with the Mandril, the index is to 
 point to the divisional line on the scale 
 which has 0 engraved over it. 
 
 It has been already suggested that the 
 Slide Plates are to act in perfect lineal 
 parallelism when the index, to that cir¬ 
 cular movement which is between them, 
 points to the division marked 12, and 
 from thence it follows, that they will 
 also act in lineal parallelism, when the 
 index points to division 6. When the 
 index points to division 3 or 9, they will 
 act at right angles to each other. When 
 the index points to division 2, 4, 8, or 
 10, their action will be at an angle of 
 60; and so on for their acting at any 
 other angle. 
 
 The Manuel du Tourneur was the first 
 book that gave any account of an Ec¬ 
 centric Chuck; and I do not now know 
 of any other book that does so. That 
 book gives, also, a description of a Com¬ 
 pound Eccentric Chuck; but according 
 
40 
 
 to the construction of it therein set forth, 
 it is an instrument very limited in its 
 action and powers. The Slide Plates 
 have no circular movement between them, 
 but are fixed to act at right angles to 
 each other; and they, moreover, can only 
 be thrown out of centre at one end of the 
 Bed Plate; but the discrepances which 
 arise from this construction of the Chuck 
 will, however, more fully appear from 
 the Specimens that will be herein given 
 of the action and powers of a Compound 
 Eccentric Chuck constructed on a dif¬ 
 ferent plan. 
 
 It appears from the title page of the 
 edition of the Manuel du Tourneur which 
 I possess, that it was published by Ber¬ 
 geron in 1792; and from that period the 
 defects I have mentioned, in the construc¬ 
 tion of the Compound Eccentric Chuck, 
 have continued unheeded by the manu¬ 
 facturer of Turning Apparatus. A new 
 Compound Eccentric Chuck, just finished 
 by one of our first-rate London manufac- 
 
41 
 
 turers, has been shewn to me, which, as 
 heretofore, partakes of these and other 
 most glaring defects. 
 
 Figure 3, is a Section—supposed to be 
 through the centre of the Chuck, and 
 coincident with the centre of the Man¬ 
 dril,—showing the internal construction 
 of the circular movements; and, in des¬ 
 cribing this Section, I will detail the 
 progress pursued b y myself in the manu¬ 
 facture and putting together of the seve¬ 
 ral parts of the Chuck. 
 
 The Boss of the Bed Plate, A. fig. 1, 
 being screwed and fitted on the screw of 
 the Mandril, a hole was turned out in 
 the centre of it equal in diameter to the 
 width of the long opening c. c. to be 
 made in the Bed Plate. The face of the 
 Bed Plate was then turned down, with 
 the Slide Rest, and cleaned off with fine 
 emery paper to a true plane; and the 
 ends of the Bed Plate were also turned 
 off with the Slide Rest. The Bed Plate 
 was now unscrewed from the Mandril to 
 
42 
 
 be chucked again in the following man¬ 
 ner, in order to the back part of it being 
 turned and polished off. I have brass 
 flanch Chucks, with holes through the 
 flanch part, for screws to pass, to attach 
 circular pieces of mahogany to them 
 about an inch in thickness. One of 
 these Chucks was screwed on the Man¬ 
 dril, and the face of the mahogany 
 countersunk with the Slide Rest, to re¬ 
 ceive, tightly, the face and ends of the 
 Bed Plate; and the Bed Plate was held 
 fast in this countersink by placing a 
 circular piece of plate brass (with a hole 
 at the centre to pass a screw) on the Boss 
 A. and screwing it to the wood. The 
 Boss A. and back of the Bed Plate was 
 now turned off and polished. The Bed 
 Plate was then unchucked, and the holes 
 drilled and screwed for the steady pins 
 and screws which attach the steel arms 
 to the Bed Plate, also the screw holes, 
 in the edge of the Bed Plate, were 
 drilled and screwed to receive the screws 
 
43 
 
 i. i.; and the long opening c. c. in the 
 Bed Plate was worked out by drilling 
 and filing. The steel arms with their 
 angular edges, having been got up with 
 the greatest care, so, as far as possible, 
 to secure the Slide Plate to traverse be¬ 
 tween them in perfect parallelism with 
 the surface of the Bed Plate, are to be 
 screwed in their places to the Bed Plate. 
 The Slide Plate having been prepared, 
 and its faces made parallel, and its edges 
 grooved and nicely fitted to slide be¬ 
 tween the steel arms, is to be placed be¬ 
 tween them on the Bed Plate, and, by the 
 adjusting screws i, i, made to move rather 
 tightly. Oil-stone dust and oil was now, 
 from time to time, applied to the grooves, 
 and the Slide Plate moved backwards and 
 forwards on the Bed Plate until the an¬ 
 gular edges of the steel arms and the 
 grooves of the Slide Plate became a per¬ 
 fect fit by grinding. During this grind¬ 
 ing process the screws i. i. were used, 
 from time to time, to keep the Slide Plate 
 
44 
 
 in rather tight contact with the steel 
 arms. 
 
 Let it now be supposed that every thing 
 exhibited in figure 5 is finished and at¬ 
 tached to the Slide Plate and Bed Plate 
 by their respective screws; and that the 
 next thing to be done is to drill the holes 
 through the pieces D. and f. fig. 1, pre¬ 
 paratory to fixing the Slide Plate screw 
 d. d. in its place. It is, evidently, most 
 essential to the good and correct working 
 of the Chuck, that this screw should lie, 
 when in its place on the Bed Plate, in a 
 perfectly parallel line with the grooved 
 edges of the Slide Plate and midway be¬ 
 tween them; and that to accomplish this 
 the greatest care must be taken in drilling 
 these holes. The Slide Plates of the 
 Chuck I work with happen to act with 
 great accuracy; and, therefore, under the 
 idea of its being acceptable to the Ama¬ 
 teur, I will detail the method I pursued 
 in adjusting the Slide Plate screws. — 
 I first ascertained the distance that the 
 
45 
 
 screw d. d. should range from the surface 
 of the Bed Plate, (see figure 1) and I filed 
 up a bit of brass plate to the exact thick¬ 
 ness, that, when it was laid on the face of 
 the Bed Plate, the edge of its upper sur¬ 
 face extended exactly to where the centre 
 of the screw d. d. should be. This bit of 
 brass served then as a gauge, and by the 
 aid of it I drew a fine line across the out¬ 
 side faces of the two pieces D. and f. which 
 marked, exactly, the distance from the face 
 of the Bed Plate where the holes were to 
 be drilled. The next thing was to ascer¬ 
 tain and make a mark in each of these lines 
 exactly equidistant from the grooved edges 
 of the Slide Plate, and midway between 
 them; and I did not succeed in doing this 
 to my mind, until I had contrived and 
 made a tool, or gauge, expressly for the 
 purpose. I give a description of this 
 gauge, as it enabled me to accomplish a 
 thing which I had previously despaired 
 of doing. 
 
46 
 
 The piece A. B. C. D. is of brass plate, 
 rather more than the eighth of an inch 
 thick. The angle at A. fits the angular 
 edges of the steel arms E. E. F. F. fig. 5, 
 and when it is applied to one of these 
 edges, the edge from A. to B. rests on the 
 face of the Bed Plate B. figure 5, and the 
 space d. d. passes over the other steel arm 
 and brings the part D. H. to the opposite 
 face of the Bed Plate. A pin of steel b. 
 b. fits into and passes through a hole dril¬ 
 led through the part of the gauge as seen 
 at D. H. and is held fast in its required 
 position by the clamp screw C. The ex¬ 
 treme end of the pin at H. b. intersects 
 the line which had been previously drawn 
 
4? 
 
 across the projecting pieces D. and f on 
 the Bed Plate fig. 1 , and by repeated trials 
 —first applying the angle A. to one steel 
 arm and then to the other, and marking 
 with a pencil the point at which the end 
 of the pin crossed the line—I, at length, 
 adjusted the end of the pin so that its ex¬ 
 treme edge pointed exactly midway be¬ 
 tween the two steel arms, and then with 
 a fine point I marked the place on the 
 pieces D. and f. At the points where the 
 cross lines intersected, which had been as¬ 
 certained in the manner I have just ex¬ 
 plained, and marked on the pieces D. and 
 f dots were now made with a centre 
 point, and holes were drilled through 
 these pieces from those dots, in the fol¬ 
 lowing manner :— The drill stock was 
 screwed on the Mandril, with a drill in 
 it of the proper size for the screw hole to 
 be drilled through D, and a pointed cen¬ 
 tre was placed in the cylinder of the front 
 centre head. The dot in the piece D. at 
 the intersection of the cross lines, was 
 
 E 
 
48 
 
 placed to the point of the drill, and the 
 dot in the piece f to the point of the 
 front centre head; and the hole was dril¬ 
 led through D. by turning the Lathe 
 round, and gradually screwing forward 
 the cylinder with the pointed centre. The 
 hole through the piece f. was then drilled 
 with a proper size drill; the centre point 
 in the front centre head being, in this case, 
 pressed into the hole that had been drilled 
 through the piece D. 
 
 By placing the screw d. d. in the situa¬ 
 tion and manner here represented, the 
 Slide Plates may be thrown out to either 
 end of the Bed Plate, thereby giving to 
 the Chuck the power of forming Squares, 
 and of executing a great deal of beautiful 
 work, which no Chuck could do that is 
 constructed on the ordinary plan of throw¬ 
 ing out at only one end. These screws, 
 moreover, should be of the same velocity 
 as the screw of the Slide Rest; that is, 
 they should have the same number of 
 threads to an inch; and, in making them. 
 
49 
 
 every possible care must be taken to secure 
 them against being, in the least, what is 
 called drunken. I worked out these 
 screws in the following manner, in the 
 Lathe with the screw stock and dies, which 
 I have found to be a very effectual way of 
 making a good and correct screw. Having 
 procured two pieces of round bar steel, 
 sufficient in diameter to form the shoulder 
 seen at/, above the letter B, I filed them 
 up to the exact length required for the 
 screw; and, having centre-pointed them 
 at each end, a conical hole was drilled at 
 one of their ends to receive the point of 
 the screw, as seen at D. These pieces 
 were then chucked between two centres, 
 and turned down, in the Lathe, in the 
 usual way, to the proper size to form the 
 screw, finishing off the shoulder and end 
 beyond it, to the dimensions as seen at f. 
 The screw dies of the proper thread for 
 the screw d. d. being placed in the screw 
 stock, one of the pieces of steel prepared 
 for the screw, as just mentioned, was put 
 
50 
 
 between the dies, and again chucked in 
 the Lathe between two centres. The 
 Lathe being turned round, the die stock 
 and dies were caused to traverse and form 
 a screw-thread from one end of the steel 
 piece to the other; and by continually 
 working the dies, backwards and forwards, 
 in this way,—using plenty of oil,—and 
 screwing up the dies by little and little, as 
 occasion served, the screw was completed. 
 These screws cannot, however, be finished 
 off until after the gun-metal rings (here¬ 
 after described) are screw-tapped and 
 finished, as they must be made to fit, or 
 screw through those rings in the most 
 perfect manner. Throughout the pro¬ 
 cess of making these screws, the die 
 stock must be kept firm and steady in 
 the two hands, and be caused to traverse 
 at right angles with the screw that is 
 being made. If the die stock be allowed, 
 in any part of its progress, to incline to 
 one side or other of the screw-piece, the 
 screw will, in that part, be imperfect—- 
 
51 
 
 will partake of the defect called drunken¬ 
 ness. 
 
 The Slide Plate is now to be adjusted 
 on the Bed Plate, exactly in the middle, 
 between its two ends; and, whilst in this 
 situation, a hole is to be drilled through 
 them both, at one corner, about half an 
 inch from the end of the Slide Plate and 
 the grooved edge. This hole is to receive 
 a steady pin, to afford the means of ad¬ 
 justing and securing the Slide Plate in the 
 same central position whenever required. 
 The Bed Plate being now screwed on the 
 Mandril, and the Slide Plate being se¬ 
 cured in its central position by the steady 
 pin, a hole is to be turned through the 
 Slide Plate of the size required to receive 
 the plug piece N. N. fig. 3, and a coun¬ 
 tersink is to be turned out round this hole 
 to receive the shoulder of the piece P. P, 
 as seen in the engraving fig. 3. The 
 Slide Plate may now be removed from the 
 Bed Plate, and the holes drilled in it, 
 screwed, and finished off for the screws 
 
52 
 
 which belong to, and fix the index t.t, fig. 
 1, and the index 3, the click 4, and the 
 spring 6, fig. 5. 
 
 The piece P. P, the plug piece N. N, 
 and the screw-nut k. k, fig. 3, are made of 
 steel; and the cylindrical piece or ring 
 q. q. fig. 3 and 4, is made of gun-metal. 
 The piece P. P. must be correctly turned 
 out to fit, tightly, into the countersink in 
 the Slide Plate. The cylindrical part of 
 the plug piece N. N. next its screwed end, 
 must fit tightly into the hole in the centre 
 of the piece P. P, and must pass, loosely, 
 through the hole in the centre of the 
 Slide Plate; thus, by the action of the 
 screw-nut k. k, the piece P. P, the Slide 
 Plate G. G, and the plug piece N. N. 
 will be attached as firmly together as 
 though they were formed out of one 
 piece of metal. The part of the plug 
 piece N. N. seen at 4, must be finished off 
 to a true cylinder, and the gun-metal ring 
 q. q. must be made to fit it, rather tightly, 
 in the most correct manner; and the ring 
 
53 
 
 being then removed from the plug,, the 
 holes are made in them to receive the 
 screw d. d. To make these holes correctly, 
 I had two drills, which run true in the 
 Lathe, of sufficient length to pass through 
 the pieces D. and f. fig. 1, and reach to the 
 plug; the shank, between the stock and 
 the point of one of these drills, exactly 
 fitted the screw-hole in the piece D. and 
 the shank of the other, the hole in the 
 piece f. When the drill was passed 
 through the screw-hole D. the front centre 
 point was pressed into the hole in the 
 piece f and the Lathe turned round 
 until the plug became drilled half through. 
 The drill which fitted the hole in the 
 piece/! was then placed in the stock, and 
 the front centre being pressed into the 
 screw-hole in the piece D. and the Lathe 
 turned round, the plug became drilled 
 through its other half, and as this was the 
 largest of the two drills, it was passed 
 quite through the plug. This hole in the 
 plug was afterwards broached out, so as 
 
54 
 
 to leave plenty of room for the screw d. d. 
 to pass through it without touching; and 
 any burr that was found on the edges of 
 the hole was carefully removed. The gun- 
 metal ring was now placed on the plug, 
 and the places marked on it where it was 
 to be drilled and screw-tapped to receive 
 the screw d. d. This was done, by means 
 of the two drills, in the same way as the 
 hole was drilled in the plug; but the drills 
 were not worked into the ring more than 
 about two-thirds of the ring’s thickness ; 
 because, if the drill were passed quite 
 through the ring, a burr would be thrown 
 up on the inside next the plug, which 
 would render it impossible to remove the 
 ring from the plug. The ring, therefore, 
 is to be taken off the plug (a mark being 
 first made on the ring to record its proper 
 position on the plug), and the holes are 
 to be completed through its two sides, 
 with a drill, of the proper size for the 
 screw d. d. fixed in the drill stock screwed 
 on the mandril, the ring being pressed 
 
55 
 
 against the drill by means of the front 
 centre point, which is to be adjusted in the 
 hole on the opposite side. The screw- 
 taps, corresponding with the screw d. d, 
 are to be passed through these holes in the 
 ring, from side to side; and the screw- 
 holes being completed with the finishing 
 tap, the screw d. d. can be now finished off* 
 (as before mentioned), so that the ring may 
 work freely, but tightly, from one end of 
 it to the other. The screw d. d. having 
 been worked through the screw of the ring 
 from end to end, two or three times, with 
 plenty of oil, the ring was taken off the 
 screw, and any burr the screwing had 
 thrown up inside the ring, was thoroughly 
 filed away with a riffler file,* as the least 
 burr would of course be an impediment to 
 the ring being placed on the plug. 
 
 The Bed Plate being screwed on the 
 
 * Riffler Files are variously shaped. The one I 
 used was bent, so that the burr could be removed 
 without defacing, in the least, the inside surface of 
 the ring. 
 
56 
 
 Mandril, and the Slide Plate secured in its 
 place by the steady pins, the piece P. P. 
 is to be turned truly over and shaped as 
 seen in fig. 3, and the holes drilled in it 
 and screw-tapped to receive the screws s. 
 s. The piece K. K. (made out of well 
 hammered brass) is to be fitted most cor¬ 
 rectly, by turning and a little grinding 
 with oil-stone dust and oil, to move round 
 the piece P. P. The piece which the 
 screws s. s. clamp to the piece P. P. is 
 turned out of a ring of steel, and by caus¬ 
 ing the flanch rim of it to protrude beyond 
 the top edge of P. P. and extend over part 
 of the top surface of K. K, the latter is 
 confined and kept firm to circulate, with¬ 
 out the least shake, on and round the piece 
 P. P. The outside surface of the brass 
 ring piece K. K. is divided into 96 divi¬ 
 sions, and figured as already explained. 
 The piece L. L. is made out of well ham¬ 
 mered brass, and the edge of it is cut into 
 96 teeth as seen in figure 1, and it is 
 shouldered into the piece K. K. in the 
 
57 
 
 manner seen in figure 3, to which it is 
 screwed by four screw s o. o. The part 3. 
 3. and other space not shaded with lines., 
 holds oil, none of which can possibly es¬ 
 cape, excepting between the bevelled sur¬ 
 faces of K. K. and P. P. being those 
 which require it. For lubricating the 
 surfaces that are in moving contact, such 
 as the surface in question, I use neat’s-foot 
 oil, which I thicken by grinding with it a 
 small portion of black-lead. 
 
 In figure 3. the toothed wheel piece L. 
 L. has a projecting part, which constitutes 
 the nose screw of the Chuck, as seen in 
 figure 1, and the whole, from the surface 
 of the Slide Plate to the top of the nose 
 screw, I designate as the Circular Move¬ 
 ment of the Second Bed Plate.” 
 
 In figure 1, the toothed wheel piece L. 
 L. forms part of the f<r Circular Movement 
 of the First Bed Plate;” and, as there 
 seen, it is screwed to the projecting part 
 at the back of the second Bed Plate. 
 This projection at the back of the second 
 
58 
 
 Bed Plate forms one casting with the 
 Plate,, and is turned off, under the same 
 plan of chucking, &c. as has been sug¬ 
 gested regarding the Boss A. at the back 
 of the first Bed Plate. A shallow counter¬ 
 sink is turned out in the toothed piece L. 
 L. into which the projection of the second 
 Bed Plate, just mentioned, must correctly 
 fit, and the Bed Plate and the piece L. L. 
 are then to be firmly screwed together by 
 four screws passing through the Bed Plate 
 at its projecting part, and screwing into 
 the toothed piece L. L. the heads of these 
 screws being, of course, countersunk in 
 the Bed Plate. 
 
 After I had constructed my Chuck on 
 the plan I have now detailed, and accord¬ 
 ing to the representation of it in the en¬ 
 graving fig. 1 , and had done a great deal 
 of work with it, and had proved it to be 
 a very efficient instrument, I yet thought 
 that greater steadiness might be obtained 
 by enlarging the diameter of the circular 
 movement of the first Bed Plate. I, ac- 
 
59 
 
 cordingly, made the alteration; and as my 
 object is to relate all I know on the sub¬ 
 ject of the Chuck, I give a diagram, of 
 this alteration, in the real dimensions of 
 the pieces which compose it. 
 
 The annexed wood-cut is a section 
 through the centre, shewing a modifica¬ 
 tion of the construction of the circular 
 movement and its appendages, which I 
 have recently introduced into my Chuck 
 on the Bed Plate next the Lathe head, in 
 substitution of the one represented by the 
 engraving, figure 3. By doubling the dia¬ 
 meter of the moving circular plate, additi¬ 
 onal steadiness is obtained; and the power 
 of angular adjustment is greatly increased 
 by having a stop wheel of 192 teeth instead 
 of one of 96; and, besides, the construc¬ 
 tion is more simple and easy. G. G. is the 
 Slide Plate, made of brass, attached to the 
 Bed Plate that screws on the Mandril. A 
 piece of steel P. P. P. P. is shouldered into 
 this Slide Plate and kept firm to it by four 
 screws (see two of them marked 4). N. re- 
 
60 
 
 presents the circular hole passing through 
 the Slide Plate and steel piece, to receive 
 the plug N, described before and shewn in 
 the engraving figure 3. A circular brass 
 plate K. K. the edge cut into 192 teeth, is 
 fitted to move round, without the least 
 shake, on the steel piece P. P. P. P. A 
 steel plate L. L. is screwed by six screws 
 (see those marked 6) to the steel piece P. 
 and the brass circle with teeth is kept 
 firmly in its place by it. The centre part 
 of the plate L. L. is turned out to make 
 room for the plug screw nut, figure 3. N. 
 Into the brass plate K. K. there are four 
 pillars S. S. screw quite tight, at an equal 
 distance from the centre of the plate and 
 from each other. O. O. is a plate of brass 
 screwed firmly to these pillars, in the man¬ 
 ner seen. When this plate is screwed to 
 the pillars the edge is turned truly round, 
 and divided and figured into twelve grand 
 divisions, and each of those divisions, again, 
 into eight parts. A slender piece of brass 
 plate is screwed to the back of the steel 
 
piece P, on one of the sides that project 
 beyond the Slide Plate, to carry the index 
 to the circular division. A piece of brass 
 plate is also attached, by screws, to the 
 back of the piece P. to carry the micro¬ 
 meter click (before described) that is to 
 act on the toothed edge of the plate K. 
 The space which is obtained by means of 
 the pillars, between L. L. and O. O. is for 
 the Slide Plate screw, which, in the en¬ 
 graving fig. 1 , is seen next to the toothed 
 wheel L. L. The second, or upper Bed 
 Plate, shewn in fig. 1 , and represented in 
 fig. 5 by B. B. is, under this modification 
 of the Chuck, substituted by O. O. The 
 steel arms E. E. F. F. seen in figure 5, are 
 attached to O. O. in like manner, as they 
 therein appear; but, as O. O. is a circular 
 plate, the adjusting screws i. i. cannot be 
 used; and, therefore, two snail-headed 
 screws may be substituted, or a bar of 
 brass, of the thickness of the adjustible 
 steel arm, may be screwed to the plate pa¬ 
 rallel to the arm, and two screws passed 
 
through it, in a plane with the plate, 
 which when screwed will press against the 
 steel arm as occasion may require. In my 
 Chuck I have adopted the latter. 
 
 Having now gone into an explanation 
 of every thing that particularly occurs to 
 me, with regard to the Compound Eccen¬ 
 tric Chuck, the next thing will be to give 
 the Specimens of simple Eccentric Turn¬ 
 ing which have appeared in the first and 
 second editions. 
 
INTRODUCTION 
 
 TO THE FORMER EDITIONS. 
 
 JL urning is now so generally resorted to 
 as an amusement, that the communication 
 of any thing, which may tend to produce 
 novelty in the art, cannot fail of being 
 interesting to the Amateur; besides, there 
 can be no better means employed to pro¬ 
 mote improvement than circulating the 
 result of experience. 
 
 Turning has been the favourite amuse¬ 
 ment of the Author for many years, and 
 from the time he first took to it, he has 
 
64 
 
 sensibly felt the advantage he would have 
 derived, could he have informed himself 
 of the progress which had been made by 
 others, and he regrets the information that 
 has daily escaped him, for want of a reci¬ 
 procity of communication among his co¬ 
 temporary Turners. With regard to him¬ 
 self, he has long had it in contemplation 
 to make known the result of some of his 
 labours; but the very great expense of get¬ 
 ting the necessary engravings executed— 
 indeed the almost impossibility of getting 
 them done at all—has hitherto prevented 
 him from carrying his intention into ef¬ 
 fect. He has, however, in pursuing his 
 object, constructed, himself, a piece of 
 Machinery which enables him to engrave 
 his own copper plates. 
 
 Having so far overcome his difficulties, 
 he ventures to offer to the attention of the 
 
65 
 
 Turner, a Series of Specimens in Eccen¬ 
 tric Circular Turning ; and should this 
 be the means of inducing others to com¬ 
 municate the result of their labours to the 
 Public, in the same or any other branch 
 of Turning, he will be much gratified. 
 
 The copper-plate Engravings represent 
 the pieces of Eccentric Circular Turning 
 to be executed on ivory, wood, or any 
 other material; and each plate is accom¬ 
 panied by such Practical Instructions, as 
 will enable any one, who has acquired 
 the least practical knowledge in the art 
 to produce the desired effect. 
 

SPECIMENS 
 
 IN 
 
 Cccentrtc Circular Cumins. 
 
 SPECIMEN I. 
 
 -- 
 
 The pattern in Eccentric Turning which 
 is described in this Specimen, and repre¬ 
 sented in the accompanying plate, is 
 peculiarly adapted for the lid of a snuff¬ 
 box ; or three or four of the centre figures 
 may be selected, and applied to decorate 
 a set of backgammon-men. 
 
 This Specimen is composed of seven sets 
 of circles, of different radii, arranged, at 
 different eccentricities, round the com¬ 
 mon centre. The number of circles which 
 compose the interior, or centre set, is 
 
68 
 
 twelve; the number in the exterior set, 
 is two hundred and eighty-eight: the 
 latter number may, however, be greater 
 than can be obtained with the common 
 eccentric chuck, and another set, there¬ 
 fore, is described, which may be substi¬ 
 tuted by those who have not the means of 
 adopting the one exhibited in the plate. 
 
 The following is a practical description 
 of the method to be pursued to produce 
 a piece of Eccentric Turning similar to 
 Plate I. 
 
 The tools with which the work is to be 
 executed are double angular. Nos. 25, 32, 
 and 36, according to Messrs. Holtzap- 
 ffel and Deyerlein’s construction of this 
 sort of tool; 1 and the slide rest is to be 
 
 1 It has been often suggested to me, that it would 
 have been better to have given a particular descrip¬ 
 tion of these tools. My answer to which has 
 always been, that, it formed no part of my plan, 
 when I published these Specimens, to give any ac¬ 
 count of the construction of the machinery. I con¬ 
 sidered that the amateur who was disposed to engage 
 in the execution of any of these Specimens, must 
 
69 
 
 set at right angles with the mandril of 
 the lathe. Fix an angular tool, No. 25 , 
 in the slide rest, and adjust the eccentric 
 chuck, slide rest, and the point of the an¬ 
 gular tool, with the nicest correctness, to 
 the common centre, and proceed to exe¬ 
 cute the interior, or centre set of circles. 
 
 necessarily be acquainted with the tools, usually 
 employed in this branch of Turning, and that it 
 was, therefore, sufficient to refer him to the manu¬ 
 factory where I knew they could be obtained, and 
 where I always procured them myself. 
 
70 
 
 FIRST SET OF CIRCLES. 
 
 9 Eccentricity equal to 3. 
 
 Radius equal to 2. 
 
 To produce the eccentricity, turn the 
 slide screw of the eccentric chuck back¬ 
 wards three turns; to produce the radius, 
 turn the slide rest screw backwards two 
 
 9 The Eccentricity and Radius are noted, in this 
 manner, throughout. My object in doing this has 
 not, I find, been exactly understood. It is this : 
 All such figures depend solely on the ratio which 
 the Eccentricity bears to the Radius. In this case 
 the ratio is as 3 to 2 ; and this being known, the 
 same figure may be produced of any size ; and the 
 same rule applies to all other cases. By attending 
 to this the patterns may be varied, in size, at 
 pleasure; and thereby the different figures, forming 
 these specimens, may be combined in various ways, 
 and infinite variety of new patterns may be produced. 
 For instance: If it were required to place this figure 
 in lieu of the centre figure, in Plate II.—As it is, it 
 would be too large; but if the eccentricity be pro¬ 
 duced by 1| turns of the screw, and the radius by 1 
 
71 
 
 turns ; 3 then describe twelve circles, equi¬ 
 distant from each other, round the com¬ 
 mon centre. These circles must be cut 
 sufficiently deep to give a sharp edge to 
 the figures, which the angular tool will 
 produce; and this effect must be obtain¬ 
 ed, although it may be attended with the 
 labour of going over the circles, and cut¬ 
 ting them deeper, a second or third time : 
 but to whatever depth this set of circles 
 be cut, the same depth must be preserved 
 throughout all the other parts of this pat¬ 
 tern, excepting the exterior set of circles, 
 regarding the depth of which, mention 
 will be hereafter made. 
 
 turn, the figure will be the same, though of only 
 half the size, and would then be small enough to 
 be introduced as the centre figure in Plate II. It 
 might also, on the same principle, be enlarged. 
 The eccentricity may be produced by turning the 
 screw 3| turns; and the radius, by turning the screw 
 2j turns. The ratio, in this case, is still as 3 to 2 j 
 but the figure becomes increased in size. 
 
 3 It is to be understood that the slide screw of the 
 eccentric chuck, and the screw of the slide rest, are 
 equal in velocity. 
 
72 
 
 SECOND SET OF CIRCLES. 
 
 Eccentricity equal to 6. 
 
 Radius equal to 1. 
 
 To produce the eccentricity, turn the 
 slide screw of the eccentric chuck back¬ 
 wards three turns; which, in addition to 
 the former, makes the eccentricity equal 
 to six. 4 To make the radius equal to one, 
 
 * I have adopted the expressions of “ turning the 
 screw backwards,” and “ turning the screw for¬ 
 wards,” as being the matter of fact, and the precise 
 things that must be done to produce the eccentricity 
 and radius. And as every one must know what is 
 meant by turning a screw backwards or forwards, I 
 adopted those expressions, as being more intelligible 
 than any other I could make use of. 
 
 1 am induced to offer this explanation, in conse¬ 
 quence of the following paragraph, which appeared 
 in a little amateur production, published two years 
 after mine. The paragraph alluded to runs thus : 
 The expression “ advancing the point," though not 
 
73 
 
 turn the slide rest screw forwards one turn, 
 which is a decrease of the former radius 
 equal to one turn. Then with the angu¬ 
 lar tool as before, describe twelve equi¬ 
 distant circles. 
 
 THIRD SET OF CIRCLES. 
 
 Eccentricity equal to 10. 
 
 Radius equal to 3. 
 
 Change the angular tool to No. 36, but, 
 before it is fixed in the slide rest, adjust 
 it to the radius and depth of the circle 
 which was last turned. Then, to produce 
 the eccentricity, turn the slide screw of 
 
 strictly correct, has been adopted in preference to 
 “ moving the small ivlieel backwards," as more intel¬ 
 ligible. 
 
74 
 
 the eccentric chuck backwards four turns; 
 and, to produce the radius, turn the slide 
 rest screw backwards two turns. Describe 
 forty-eight equidistant circles. 
 
 FOURTH SET OF CIRCLES. 
 
 Eccentricity equal to 3. 
 
 Radius equal to 16. 
 
 Proceed with the same angular tool, 
 and, to produce the eccentricity for this 
 set, turn the slide screw of the eccentric 
 chuck forwards seven turns. To produce 
 the radius, encrease the former radius by 
 turning the slide rest screw backwards 
 thirteen turns. Then describe twenty- 
 four equidistant circles. 
 
75 
 
 FIFTH SET OF CIRCLES. 
 
 Eccentricity equal to 23. 
 Radius equal to 4\. 
 
 Continue with the same angular tool. 
 The eccentricity is to be encreased by 
 turning the slide screw of the eccentric 
 chuck backwards twenty turns; and the 
 radius is to be decreased by turning the 
 slide rest screw forwards eleven turns and 
 a half. Then (supposing the eccentric 
 circle to be divided into ninety-six,) be¬ 
 gin at eccentric division No. 96, and 
 describe sixteen circles: miss eight divi¬ 
 sions, set the eccentric circle to division 
 No. 24, and describe sixteen more circles: 
 miss eight divisions, set the eccentric 
 circle to No. 48, and describe sixteen 
 more circles: miss eight divisions, set the 
 
76 
 
 eccentric circle to No. 72 , and describe 
 sixteen more circles. 
 
 SIXTH SET OF CIRCLES. 
 
 Eccentricity equal to 29j. 
 
 Radius equal to 2. 
 
 Change the angular tool to No. 25; 
 which^ before it is fixed in the slide rest; 
 must be adjusted to the radius and depth 
 of the circle last turned. The eccentricity 
 is then to be encreased by turning the 
 slide screw of the eccentric chuck back¬ 
 wards six turns and a half, and the radius 
 is to be decreased by turning the slide rest 
 screw forwards two turns and a half. 
 Describe ninety-six equidistant circles. 
 
77 
 
 SEVENTH SET OF CIRCLES . 
 
 Eccentricity equal to 33. 
 
 Radius equal to |. 
 
 Change the angular tool to [No. 32 ; 
 and, before it is fixed in the slide rest, 
 adjust it to the radius of the circles last 
 turned. The eccentricity is then to be 
 increased by turning the slide screw of the 
 eccentric chuck backwards three turns 
 and a half; and the radius is to be de¬ 
 creased by turning the slide rest screw 
 forwards one and three-eighths of a turn. 
 Describe two hundred and eighty-eight 
 equidistant circles, not, however, of the 
 depth of the circles previously turned, 
 but of such a depth only as will just make 
 the figures which the tool leaves, sharp at 
 top. Or, for common eccentric chucks, 
 the following may be adopted. 
 
 G 
 
78 
 
 SEVENTH SET OF CIRCLES. 
 
 ADAPTED TO AN ECCENTRIC DIVISION OF NINETY-SIX. 
 
 Eccentricity equal to 33. 
 
 Radius equal to 1. 
 
 Proceed exactly in the same manner as 
 described for the set of two hundred and 
 eighty-eight circles: the only difference 
 is, that, in this set, the radius is to be 
 made equal to one turn of the slide rest 
 screw, and the number of equidistant cir¬ 
 cles must be limited to ninety-six. 
 
79 
 
 SPECIMEN II. 
 
 This Specimen consists of seventeen sets 
 of circles., of different eccentricities and 
 radii, arranged round the common centre, 
 in the manner represented in Plate II. 
 
 The exterior sets are produced by an 
 eccentric circular division of two hundred 
 and eighty-eight, and are formed into the 
 figure of an Etruscan Border; but, as 
 this high number of divisions cannot 
 be obtained with the common eccentric 
 chuck, a method is hereafter described, 
 by which a Border, similar in figure, may 
 be produced with an eccentric circular 
 division of only ninety-six. 
 
 To produce a piece of Eccentric Circu¬ 
 lar Turning, similar to the pattern repre- 
 
80 
 
 sented in Plate II, the following arrange¬ 
 ment must be minutely attended to. 
 
 The work, in the first instance, is to be 
 brought to a plane and polished surface ; 
 and the eccentric circles are to be execu¬ 
 ted, with double angular tools. Nos. 28 
 and 36. Set the slide rest at right angles 
 with the mandril of the lathe, and let it 
 remain in that position until the work be 
 completed. Fix an angular tool. No. 28, 
 in the slide rest, and adjust its point, the 
 eccentric chuck, and the slide rest, to the 
 common centre, with the greatest possible 
 correctness; then proceed to execute the 
 interior, or centre set of circles: these 
 circles are not to be cut deep into the 
 surface of the work; but must be cut suf¬ 
 ficiently so to leave the figures sharp at 
 top. 
 
81 
 
 FIRST SET OF CIRCLES. 
 
 Eccentricity equal to 1. 
 Radius equal to \. 
 
 To produce the eccentricity, turn the 
 slide screw of the eccentric chuck back¬ 
 wards one turn. To produce the radius, 
 turn the slide rest screw backwards half a 
 turn. Describe twelve equidistant circles. 
 
 SECOND SET OF CIRCLES. 
 
 Eccentricity equal to 4. 
 
 Radius equal to 1|. 
 
 To produce this eccentricity, increase 
 the former eccentricity by turning the 
 
82 
 
 slide screw of the eccentric chuck back¬ 
 wards three turns; and to produce this 
 radius, increase the former radius by turn¬ 
 ing the slide rest screw backwards one 
 turn; then, with the same tool as be¬ 
 fore, describe twelve equidistant circles. 
 These circles must be cut considerably 
 deeper than the first set of circles; rather 
 more so than will be sufficient to leave 
 the figure, which is formed by the inter¬ 
 section of the circles, sharp at top : but 
 to whatever depth these circles are cut, 
 the same depth must be preserved in all 
 the sets of circles remaining to be exe¬ 
 cuted ; excepting those composing the 
 border, regarding which mention will be 
 hereafter made. 
 
83 
 
 THIRD SET OF CIRCLES. 
 
 Eccentricity equal to 7\. 
 
 Radius equal to 2. 
 
 Change the angular tool, and fix No. 36 
 in the slide rest; but,, before it is fixed, 
 adjust its point to the radius and depth 
 of the circle last turned. Then produce 
 the eccentricity by turning the slide screw 
 of the eccentric chuck backwarks three 
 turns and a half; and produce the radius, 
 by turning the slide rest screw backwards 
 half a turn. Describe thirty-two circles 
 at the following distances: viz. (sup¬ 
 posing the circle of the eccentric chuck 
 to be divided into ninety-six,) begin at 
 division 96, and describe eight circles, 
 one circle at every alternate succeeding 
 division : miss eight succeeding divisions, 
 set the eccentric circle at division 24, 
 
84 
 
 and describe eight more circles, one circle 
 at each alternate . division : miss eight 
 succeeding divisions, set the eccentric 
 circle at division 48, and describe eight 
 more circles, one circle at each alternate 
 division : miss eight succeeding divisions, 
 set the circle of the eccentric chuck at 
 division 72, and describe eight circles as 
 before. 
 
 FOURTH SET OF CIRCLES. 
 
 Eccentricity equal to 13. 
 
 Radius equal to 3y. 
 
 Change the angular tool, and fix No. 28 
 in the slide rest; but, before it is fixed, 
 adjust its point to the radius and depth 
 of the circle last turned. Produce the 
 eccentricity by turning the slide screw of 
 
85 
 
 the eccentric chuck backwards five turns 
 and a half. Produce the radius by turn¬ 
 ing the slide rest screw backwards one 
 turn and a half. Then describe forty- 
 eight equidistant circles. 
 
 FIFTH SET OF CIRCLES. 
 
 Eccentricity equal to 19f. 
 Radius equal to 3-|. 
 
 Change the angular took, and fix No. 36 
 in the slide rest; but, before it is fixed, 
 adjust its point to the radius and depth 
 of the circle last turned. The eccentri¬ 
 city is to be produced by turning the slide 
 screw of the eccentric chuck backwards 
 six turns and three-fourths: the radius 
 remains as before. Describe sixty-four 
 
86 
 
 circles, and arrange them in the following 
 manner: viz. Set the eccentric circle at 
 division 96, and describe sixteen circles, 
 one circle at each following division: 
 miss eight divisions, set the eccentric cir¬ 
 cle at division 24, and describe sixteen 
 more circles: miss eight divisions, set 
 the eccentric circle at division 48, and 
 describe sixteen more circles : miss eight 
 divisions, set the eccentric circle at divi¬ 
 sion 72, and describe sixteen circles as 
 before. 
 
 SIXTH SET OF CIRCLES. 
 
 Eccentricity equal to 19| 
 Radius equal to \ 
 
 Proceed with the same angular tool. 
 No. 36, and with the same eccentricity. 
 
87 
 
 Decrease the radius by turning the slide 
 rest screw forwards three turns. Then 
 (supposing the eccentric circle to be di¬ 
 vided into ninety-six) describe four cir¬ 
 cles, one circle at each of the divisions 
 undernamed: viz. at division 20, 44, 
 68, 92. 
 
 SEVENTH SET OF CIRCLES. 
 
 Eccentricity equal to 21|. 
 
 Radius equal to 1. 
 
 Proceed with the same angular tool. 
 No. 36. Increase the eccentricity by 
 turning the slide screw of the eccentric 
 chuck backwards two turns: and in¬ 
 crease the radius by turning the slide 
 rest screw backwards half a turn. Then 
 
88 
 
 describe four circles,, one circle at each 
 of the following divisions, viz. at 20, 44, 
 68, 92. 
 
 EIGHTH SET OF CIRCLES. 
 
 Eccentricity equal to 17|. 
 
 Radius equal to 1. 
 
 Proceed with the same angular tool. 
 No. 36. Decrease the eccentricity by 
 turning the eccentric slide screw forwards 
 four turns ; and, with the same radius as 
 before, describe four circles, one at each 
 of the following divisions, viz. 20, 44, 
 68, 92. 
 
89 
 
 NINTH SET OF CIRCLES. 
 
 Eccentricity equal to 30. 
 Radius equal to 
 
 Change the angular tool., and fix No. 28 
 in the slide rest; but, before it is fixed, 
 adjust its point to the radius of the circle 
 last turned. The circles in this and the 
 succeeding sets, which compose the Etrus¬ 
 can Border, are to be cut no deeper than 
 will make the figures perfect at top. 
 
 Produce the eccentricity by turning the 
 slide screw of the eccentric chuck back¬ 
 wards twelve turns and a quarter; and 
 reduce the radius by turning the slide 
 rest screw forwards half a turn. 
 
 The set of circles now to be produced, 
 is the exterior of the nine sets which form 
 the Etruscan Border. The circles in this 
 set are two hundred and forty, which are 
 to be described in the following manner : 
 Set the circle of the eccentric chuck 
 
90 
 
 
 (which is supposed to be divided into two 
 hundred and eighty-eight) at division 5, 
 and describe twenty circles, one circle 
 at that and at each succeeding division : 
 miss four divisions, set the circle of the 
 eccentric chuck at division 29, and de¬ 
 scribe twenty circles as before : miss four 
 divisions, set the circle of the eccentric 
 chuck at division 53, and describe twenty 
 more circles; and so on for the rest of 
 this set, which, if correctly executed, 
 will be completed by describing the last 
 circle, in the last series of twenty, at 
 division 288. 
 
91 
 
 TENTH SET OF CIRCLES /’ 
 
 Eccentricity equal to 29^. 
 Radius equal to 
 
 Proceed with the same angular tool 
 and radius as before; and decrease the ec¬ 
 centricity by turning the eccentric slide 
 screw forwards five-eighths of a "turn. The 
 circles in this set are twenty-four, and are 
 to be described at the following distances. 
 Set the circle of the eccentric chuck at 
 division 5., and describe one circle: miss 
 eighteen divisions, set the circle of the ec¬ 
 centric chuck at division 24, and describe 
 one circle: miss four divisions, and de¬ 
 scribe one circle at the succeeding divi¬ 
 sion ; and so on, missing eighteen and 
 four divisions alternately, and describing 
 one circle at each division between those 
 
 * This and the following Illustrations exhibit the 
 progress of the Etruscan Border 5 the lowermost 
 circles being those which are to be produced. 
 
92 
 
 two series, till the last circle being descri¬ 
 bed at division 288, completes the set. 
 
 ELEVENTH SET OF CIRCLES. 
 
 Eccentricity equal to 28f. 
 Radius equal to 
 
 Decrease the eccentricity by turning 
 the slide screw of the eccentric chuck 
 forwards five-eighths of a turn; and then 
 proceed, with the same angular tool and 
 radius as before, to describe twenty-four 
 circles in the same manner as directed for 
 the tenth set. 
 
 *1 
 

 93 
 
 TWELFTH SET OF CIRCLES. 
 
 Eccentricity equal to 28| 
 Radius equal to \ 
 
 Decrease the eccentricity by turning 
 the slide screw of the eccentric chuck 
 forwards five-eighths of a turn; and pro¬ 
 ceed to describe twenty-four circles in the 
 same manner as directed for the tenth set. 
 
 THIRTEENTH SET OF CIRCLES. 
 
 Eccentricity equal to 2 7\. 
 Radius equal to 
 
 Proceed with the same angular tool and 
 radius as before; and decrease the eccen¬ 
 tricity by turning the slide screw of the 
 
 H 
 
94 
 
 eccentric chuck forwards five-eighths of 
 a turn. This set consists of one hundred 
 and eighty circles, which are to be de¬ 
 scribed in the following manner: Set 
 the circle of the eccentric chuck at divi¬ 
 sion 5, and describe fifteen circles, one 
 circle at that and at each succeeding di¬ 
 vision : miss four divisions, set the circle 
 of the eccentric chuck at division 24, and 
 describe one circle: miss four divisions, 
 set the circle of the eccentric chuck at 
 division 29, and describe fifteen circles: 
 and so on for the remaining divisions of 
 this set. 
 
95 
 
 FOURTEENTH SET OF CIRCLES. 
 
 Eccentricity equal to 26|. 
 Radius equal to 
 
 Proceed with the same angular tool 
 and radius as before; and decrease the 
 eccentricity by turning the slide screw of 
 the eccentric chuck forwards five-eighths 
 of a turn. 
 
 This set consists of twenty-four circles, 
 which are to be described at the following 
 distances : Set the circle of the eccentric 
 chuck at division 288, and describe one 
 circle: miss eighteen divisions, set the cir¬ 
 cle of the eccentric chuck at division 19, 
 and describe one circle : miss four divi¬ 
 sions, and describe one circle at the suc¬ 
 ceeding division : and so on, missing eigh¬ 
 teen and four divisions alternately, and 
 describing one circle at each division be¬ 
 tween those two series, till the last circle 
 
96 
 
 being* described at division 283, com- 
 pletes the set. 
 
 FIFTEENTH SET OF CIRCLES. 
 
 Eccentricity equal to 26|. 
 Radius equal to 
 
 Decrease the eccentricity by turning 
 the slide screw of the eccentric chuck 
 forwards five-eighths of a turn: and then 
 proceed, with the same angular tool and 
 radius as before, to describe twenty-four 
 circles, in the same manner as directed 
 for the fourteenth set. 
 
97 
 
 SIXTEENTH SET OF CIRCLES. 
 
 Eccentricity equal to 25 
 Radius equal to 
 
 Decrease the eccentricity by turning 
 the slide screw of the eccentric chuck 
 forwards five-eighths of a turn; and then,, 
 with the same radius and angular tool as 
 before, describe twenty-four circles at si¬ 
 milar distances to those of the fourteenth 
 set. 
 
 SEVENTEENTH SET CIRCLES. 
 
 Eccentricity equal to 25. 
 Radius equal to ■§. 
 
 Decrease the eccentricity by turning 
 the slide screw of the eccentric chuck for- 
 
98 
 
 wards five-eighths of a turn, and proceed 
 with the same angular tool and radius as 
 before. This set of circles completes the 
 Etruscan Border, being the interior of the 
 nine sets of which that Border is com¬ 
 posed. There is the same number of cir¬ 
 cles in this as in the exterior or ninth set,, 
 viz. two hundred and forty, which are 
 to be described in the following manner: 
 Set the circle of the eccentric chuck at 
 division 288, and describe twenty circles, 
 one circle at that and at each succeeding 
 division : miss four divisions, set the circle 
 of the eccentric chuck at division 24, and 
 describe twenty circles as before : miss 
 four divisions, set the circle of the eccen¬ 
 tric chuck at division 48, and describe 
 twenty more circles: and so on for the 
 rest of this set, which will be completed, 
 if correctly executed, by the last circle, in 
 the last series of twenty, being described 
 at 283. 
 
 The labour attending the execution of 
 borders of this sort is very considerable. 
 
99 
 
 particularly when they are composed of 
 so minute a circular division as that just 
 described. This alone will probably be 
 sufficient to induce attention to correct¬ 
 ness in placing the circles at their assigned 
 distances; for it must be recollected that 
 the omission of a circle would considera¬ 
 bly injure the general effect, and a circle 
 misplaced would totally spoil it. 6 
 
 By the following method an Etruscan 
 Border, similar in figure to that which 
 is represented in Plate II, may be pro¬ 
 duced with an eccentric circular division 
 of only ninety-six. This Border consists 
 of five sets of circles, which are to be cut 
 sufficiently deep to make the figure per¬ 
 fect at top. 
 
 6 At the time I wrote this I was unconscious I 
 had afforded an opportunity of applying these re¬ 
 marks. In the copper-plate Engraving (No. 2.) 
 I had omitted every alternate circle in the second 
 set of circles in the Etruscan Border. This circle 
 was, however, properly inserted in the wood-cut 
 illustration (see 17th set of circles). The omission 
 of it in the copper-plate is not only very apparent. 
 
1(X) 
 
 NINTH SET OF CIRCLES. 
 
 ADAPTED TO AN ECCENTRIC CIRCULAR DIVISION 
 OF NINETY-SIX. 
 
 Eccentricity equal to 33. 
 Radius equal to |. 
 
 Change the angular tool, and fix No. 28 
 in the slide rest; but, before it is fixed, 
 adjust its point to the radius of the circle 
 last turned. Produce the eccentricity 
 and radius, and make them greater than 
 required for the ninth set, adapted to an 
 eccentric division of two hundred and 
 eighty-eight, by three turns backwards 
 of the slide screw of the eccentric chuck, 
 and three-eighths of a turn backwards of 
 the slide rest screw. 
 
 but may, certainly, be said to “ injure the general 
 effect.” It was not, however, discovered until after 
 it was before the Public, and it will now serve as 
 a beacon to those who may be desirous of perfecting 
 such kind of work. 
 
101 
 
 This set of circles is the exterior of the 
 five sets which are, now, to form the 
 Etruscan Border : the number of circles 
 in this set is eighty-four, which are to be 
 described in the following manner. 
 
 Set the circle of the eccentric chuck 
 (which is supposed to be divided into 
 ninety-six) at division 2, and describe 
 seven circles, one circle at that and at 
 each succeeding division: miss one divi¬ 
 sion, set the circle of the eccentric chuck 
 at division 11, and describe seven circles 
 as before: miss one division, set the cir¬ 
 cle of the eccentric chuck at division 19, 
 and describe seven more circles: and so 
 on for the rest of this set, which, if cor¬ 
 rectly executed, will be completed by 
 describing the last circle, in the last series 
 of seven, at division 96. 
 
102 
 
 TENTH SET OF CIRCLES. 
 
 Eccentricity equal to 31 T J 5 
 Radius equal to . 
 
 Proceed with the same angular tool 
 as before. Decrease the eccentricity by 
 turning the slide screw of the eccentric 
 chuck forwards one turn and fifteen- 
 sixteenths of a turn. Decrease the radius 
 by turning the slide rest screw forwards 
 one-sixteenth of a turn. The circles in 
 this set are twenty-four, which are to be 
 described at the following distances : Set 
 the circle of the eccentric chuck at divi¬ 
 sion 2, and describe one circle : miss five 
 divisions, set the circle of the eccentric 
 chuck at division 8, and describe one cir¬ 
 cle : miss one division, set the circle of 
 the eccentric chuck at division 10, and 
 describe one circle : and so on, missing 
 five divisions and one division alternately. 
 
103 
 
 and describing one circle at each inter¬ 
 mediate division, till the last circle, being 
 described at division 96, completes the 
 set. 
 
 ELEVENTH SET OF CIRCLES. 
 
 Eccentricity equal to 29^. 
 Radius equal to f. 
 
 Proceed with the same angular tool as 
 before. Decrease the eccentricity by turn¬ 
 ing the slide screw of the eccentric chuck 
 forwards one turn and fourteen-sixteenths 
 of a turn. Decrease the radius by turn¬ 
 ing the slide rest screw forwards one-six¬ 
 teenth of a turn. There are seventy-two 
 circles in this set, which are to be de¬ 
 scribed in the following manner : Set the 
 circle of the eccentric chuck at division 
 2, and describe five circles, one circle at 
 
104 
 
 that and at each succeeding division: 
 miss one division, set the circle of the 
 eccentric chuck at division 8„ and describe 
 one circle : miss one division, set the cir¬ 
 cle of the eccentric chuck at division 10, 
 and describe five circles: and so on, till 
 this set be completed. 
 
 TWELFTH SET OF CIRCLES. 
 
 Eccentricity equal to 2 7 T 6 g. 
 Radius equal to 
 
 The same angular tool as before. De¬ 
 crease the eccentricity by turning the 
 slide screw of the eccentric chuck for¬ 
 wards one turn and thirteen-sixteenths of 
 a turn. Decrease the radius by turning 
 the slide rest screw forwards one-sixteenth 
 of a turn. This set consists of twenty- 
 * four circles, which are to be described at 
 
105 
 
 the following distances: Set the circle 
 of the eccentric chuck at division 96, 
 and describe one circle: miss five divi¬ 
 sions, set the circle of the eccentric chuck 
 at division 6, and describe one circle : 
 miss one division, and describe one circle 
 at the succeeding division: and so on, 
 missing five divisions and one division 
 alternately, and describing one circle at 
 the intermediate divisions, till the set be 
 completed. 
 
 THIRTEENTH SET OF CIRCLES. 
 
 Eccentricity equal to 2o|. 
 Radius equal to f. 
 
 Decrease the eccentricity by turning 
 the slide screw of the eccentric chuck 
 forwards one turn and ten-sixteenths of a 
 turn Decrease the radius by turning the 
 
106 
 
 slide rest screw forwards one-sixteenth of 
 a turn; then proceed with the same an¬ 
 gular tool as before. This set of circles 
 completes the Etruscan Border, adapted 
 to an eccentric circular division of ninety- 
 six. It consists of as many circles as the 
 exterior set, viz. eighty-four, which are 
 to be described in the following manner : 
 Set the circle of the eccentric chuck at 
 division 96, and describe seven circles, 
 one circle at that and at each succeeding 
 division : miss one division, set the circle 
 of the eccentric chuck at division 8, and 
 describe seven circles as before : miss one 
 division, set the circle of the eccentric 
 chuck at division 16, and describe seven 
 circles: and so on, till the set be com¬ 
 pleted at division 94. 
 
107 
 
 SPECIMEN III. 
 
 —— 
 
 This Specimen is composed of five sets 
 of circles., of various radii, which are ar¬ 
 ranged round the common centre,, at dif¬ 
 ferent eccentricities, in the manner repre¬ 
 sented in the accompanying Plate (III): 
 by reference to this Plate, aided by the 
 following data, the Turner will be ena¬ 
 bled to produce a corresponding piece of 
 Turning. 
 
 The tools to be used are double angu¬ 
 lar, Nos. 28 and 36; and the slide rest is 
 to be set at right angles with the mandril 
 of the lathe. The work to be turned (be¬ 
 ing first properly fixed in the eccentric 
 chuck) must be brought to a plane and 
 polished surface : then fix the angular 
 tool No. 36, in the slide rest; and, after 
 
108 
 
 adjusting its point, the eccentric chuck, 
 and the slide rest, to the common centre, 
 with the greatest possible correctness, 
 proceed to execute the centre, or interior 
 set of circles. 
 
 FIRST SET OF CIRCLES. 
 
 Eccentricity equal to 1 *. 
 
 Radius equal to 1£. 
 
 Produce the eccentricity by turning the 
 slide screw of the eccentric chuck back¬ 
 wards one turn and a quarter. Produce 
 the radius by turning the slide rest screw 
 backwards one turn and an eighth of a 
 turn. Then describe eight equidistant 
 circles: these circles are to be cut suffi¬ 
 ciently deep to make the figure, which is 
 
109 
 
 left by the intersection of the circles, 
 sharp at top; and the same depth must be 
 preserved throughout all the other sets. 
 
 SECOND SET OF CIRCLES. 
 
 Eccentricity equal to 4|. 
 
 Radius equal to < 1 \. 
 
 To obtain the eccentricity turn the slide 
 screw of the eccentric chuck backwards 
 three turns and a quarter. To obtain the 
 radius turn the slide rest screw backwards 
 one turn. Then, with the same angular 
 tool as before, describe twenty-four equi¬ 
 distant circles. 
 
 i 
 
110 
 
 THIRD SET OF CIRCLES. 
 
 Eccentricity equal to 5^ 
 
 Radius equal to Ilf. 
 
 Produce the eccentricity by turning 
 the slide screw of the eccentric chuck 
 backwards five-eighths of a turn. Pro¬ 
 duce the radius by turning the slide rest 
 screw backwards nine turns and five 
 eighths of a turn. Then, with the same 
 tool. No. 36 , as before, describe twenty- 
 four equidistant circles. 
 
Ill 
 
 FOURTH SET OF CIRCLES. 
 
 Eccentricity equal to 21|. 
 
 Radius equal to 4f. 
 
 Change the angular tool, and fix No. 28 
 in the slide rest; but, before it is fixed, 
 adjust its point to the radius and depth 
 of the circle last turned. To produce the 
 eccentricity add to that required for the 
 preceding set, by turning the slide screw 
 of the eccentric chuck backwards sixteen 
 turns and three-eighths of a turn. To 
 produce the radius decrease that which 
 was required for the preceding set, by 
 turning the slide rest screw forwards seven 
 turns. Describe ninety-six equidistant 
 circles. 
 
112 
 
 FIFTH SET OF CIRCLES . 
 
 Eccentricity equal to 27|. 
 Radius equal to If. 
 
 Increase the eccentricity required for 
 the set last described^ by turning the slide 
 screw of the eccentric chuck backwards 
 six turns and a quarter; and decrease the 
 radius by turning the slide rest screw for¬ 
 wards three turns and a quarter. Then 
 describe ninety-six equidistant circles. 
 
113 
 
 SPECIMEN IV. 
 
 — 
 
 This Specimen consists of five sets of 
 circles, which form the outermost figures, 
 and of five sets of arcs of circles, or curved 
 lines, which form the centre figure. The 
 circles are of different radii, and are ar¬ 
 ranged, at different eccentricities, round 
 the common centre. The arcs of circles, 
 or curved lines, are all of the same radius 
 and eccentricity, and are produced from 
 the point of the common centre, but vary 
 in their measure. Plate IV represents the 
 arrangement of these circles and arcs; 
 which, together with the following prac¬ 
 tical directions, will enable the workman 
 to execute a corresponding piece of Ec¬ 
 centric Turning. 
 
 In order to understand the description, 
 hereafter given, of the method by which 
 
114 
 
 the arcs of circles, or curved lines, are to 
 be produced, the following observations 
 must be attended to. 
 
 It must be recollected, that, in Eccen¬ 
 tric Turning, all circles and arcs of cir¬ 
 cles, are produced by the rotation of the 
 lathe; that the radius of all circles, and 
 of all arcs of circles, depend on the ad¬ 
 justment of the slide rest; and that the 
 locality, or what is called eccentricity in 
 this kind of Turning, of all circles, and 
 of all arcs of circles, is assigned to them 
 by the operation of the eccentric chuck. 
 If a tool, therefore, be applied to the 
 surface of the work, at any point with¬ 
 out the centre of the lathe’s motion, and 
 the pulley wheel, which gives motion to 
 the mandril of the lathe, be moved com¬ 
 pletely round, a circle will be described: 
 if the pulley wheel be moved but half 
 round, the tool will describe a semicircle, 
 or an arc of 180 degrees : and if the pul¬ 
 ley wheel be moved but a quarter round, 
 the tool will describe a quadrant, or arc 
 
115 
 
 of 90 degrees. The pulley wheel which 
 gives motion to the mandril of the lathe, 
 affords., consequently, the practical means 
 of measuring all arcs or curved lines; and 
 it will give their measure both minutely 
 and correctly, if a circle on the face of 
 it be divided into some convenient num¬ 
 ber of parts. For instance, suppose such 
 circle were divided into forty-eight parts, 
 and that to produce an arc, or curved 
 line, the said pulley wheel be moved 
 forwards twelve of those parts, the mea¬ 
 sure of the arc, or curved line, thereby 
 produced, would be equal to if the 
 pulley wheel be moved twenty-four divi¬ 
 sions, the measure of the curve would be 
 equal to -f—j & c - & c - ^ * s on this P r * n “ 
 
 ciple that the curved lines in question 
 are produced, and that the measure of 
 them is defined. 
 
 The work to be turned must be fixed 
 in the eccentric chuck, and brought to a 
 plane and polished surface; a double an¬ 
 gular tool. No. 32 , may be used through- 
 
116 
 
 out this piece of Eccentric Turning; and 
 the slide rest is to be set at right angles 
 with the mandril of the lathe. 
 
 Fix the angular tool in the slide rest, 
 and adjust its point, the eccentric chuck, 
 and the slide rest, to the common centre, 
 with every possible degree of correctness. 
 In this state of things, move the lathe 
 round, and pressing the point of the 
 angular tool gently against the surface 
 of the work, describe a very minute dot ; 
 from which dot all the curved lines, which 
 form the centre figure, are to be pro¬ 
 duced, in the following manner. 
 
117 
 
 FIRST SET OF ARCS, 
 
 Eccentricity equal to 5. 
 
 Radius equal to 5. 
 
 Measure of the arcs 
 
 Produce the eccentricity and radius by 
 turning the slide screw of the eccentric 
 chuck and the slide rest screw backwards 
 five turns each. Set the circle of the ec¬ 
 centric chuck at division 96, turn round 
 the mandril pulley wheel until the dot, 
 at the common centre, comes under the 
 point of the tool; and then, setting the 
 point of the tool in this dot, describe a 
 curved line by moving the pulley wheel 
 forwards (supposing it to be divided into 
 48) twelve divisions. 7 Then describe five 
 other arcs, or curved lines, one at each 
 
 7 It would tend very greatly to the correct execu¬ 
 tion of this centre figure, if stops were to be applied 
 
118 
 
 of the following divisions of the circle of 
 the eccentric chuck, 16, 32 , 48, 64, 80. 
 
 to the pulley wheel, so as to secure it from moving, 
 either way, beyond the intended limits of the curve. 
 
 Since the first edition was published I have seen 
 various methods of stopping the pulley wheel, dif¬ 
 ferent to that I had, myself, adopted. Most of the 
 lathe makers have now some contrivance they affix 
 to their lathes, which they call the “ segment stop.” 
 These contrivances are available for executing the 
 arcs of circles in question, and all others ; but why 
 the lathe makers call it the segment stop I cannot 
 say. It would have been better if it had been 
 called otherwise, as there is no possible motion of 
 the lathe that can describe the segment of a circle. 
 Every curved line that is produced by the motion 
 of the mandril of the lathe, must be either a circle, 
 or an arc of a circle ■, whilst a segment of a circle 
 is a superfices comprehended between two lines, 
 viz. by a straight line denominated a chord, and by 
 a curved line, denominated an arc. 
 
119 
 
 SECOND SET OF ARCS . 9 
 
 Eccentricity equal to 5 
 Radius equal to 5. 
 Measure of the arcs |-g. 
 
 These arcs, or curved lines, are to be 
 produced from the centre dot, in the same 
 manner as those of the former set, but the 
 pulley wheel is to be moved only eleven 
 divisions. There are twelve curved lines 
 of this measure to be described, one at 
 each of the under-named divisions of the 
 circle of the eccentric ckuck, viz. 2, 14, 
 18, 30, 34, 46, 50, 62, 66, 78, 82, 94. 
 
 8 In this and the following illustrations of the 
 arcs, the lines which meet at the centre are those 
 which are to be produced. 
 
120 
 
 THIRD SET OF ARCS. 
 
 Eccentricity equal to 5. 
 
 Radius equal to 5. 
 
 Measure of the arcs 
 
 Produce six arcs, one at each of the 
 following divisions of the circle of the 
 eccentric chuck, viz. 4, 20, 36, 52, 68, 
 84. 
 
 FOURTH SET OF ARCS. 
 
 Eccentricity equal to 5. 
 Radius equal to 5. 
 Measure of the arcs 
 
 Produce six arcs, one at each of the 
 following divisions of the circle of the ec¬ 
 centric chuck, viz. 6, 22, 38, 54, 70, 86. 
 
121 
 
 FIFTH SET OF ARCS. 
 
 Eccentricity equal to 5. 
 
 Radius equal to 5. 
 
 Measure of the arcs 
 
 Produce twelve arcs, one at each of the 
 following divisions of the circle of the 
 eccentric chuck, viz. 8, 12, 24, 28, 40, 
 44, 56, 60, 72, 76, 88, 92. 
 
 FIRST SET OF CIRCLES. 
 
 Eccentricity equal to 14£. 
 Radius equal to 5. 
 
 Proceed with the same angular tool and 
 radius as before. Increase the eccentri- 
 
122 
 
 city by turning the slide screw of the 
 eccentric chuck backwards nine turns 
 and one-eighth of a turn; and then (sup¬ 
 posing the circle of the eccentric chuck 
 to be divided into 96) produce forty- 
 eight circles in the following manner: viz. 
 
 Describe one circle at division 96: set 
 the circle of the eccentric chuck at divi¬ 
 sion J, and describe another circle: miss 
 two divisions, set the circle of the eccen¬ 
 tric chuck at division 4, and describe 
 a circle: set the circle of the eccentric 
 chuck at division 5, and describe another 
 circle; and so on, missing every alternate 
 two divisions, till the forty-eight circles 
 be completed. 
 
123 
 
 SECOND SET CIRCLES. 
 
 Eccentricity equal to 19f. 
 
 Radius equal to f. 
 
 The same angular tool as before. Pro¬ 
 duce the eccentricity by turning the slide 
 screw of the eccentric chuck backwards 
 five turns and five-eighths of a turn. 
 Produce the radius by turning the slide 
 rest screw forwards four turns and a half. 
 Describe ninety-six equidistant circles. 
 
m 
 
 THIRD SET OF CIRCLES. 
 
 Eccentricity equal to 24-|. 
 
 Radius equal to 4. 
 
 The same angular tool as before. Pro¬ 
 duce the eccentricity by turning the slide 
 screw of the eccentric chuck backwards 
 four turns and three-fourths of a turn. 
 Produce the radius by turning the slide 
 rest screw forwards three turns and a half. 
 Describe thirty-two equidistant circles. 
 
125 
 
 FOURTH SET OF CIRCLES. 
 
 Eccentricity equal to 29\. 
 Radius equal to 2f. 
 
 The same angular tool as before. In¬ 
 crease the eccentricity by turning the 
 slide screw of the eccentric chuck back¬ 
 wards five turns. Decrease the radius by 
 turning the slide rest screw forwards one 
 turn and a half. Describe thirty-two 
 equidistant circles. 
 
 K 
 
126 
 
 FIFTH SET CIRCLES . 
 
 Eccentricity equal to 30-| 
 Radius equal to 2. 
 
 The same angular tool as before. In¬ 
 crease the eccentricity by turning the 
 slide screw of the eccentric chuck back¬ 
 wards one turn. Decrease the radius by 
 turning the slide rest screw forwards half 
 a turn. Describe thirty-two equidistant 
 circles: these circles are not to be pro¬ 
 duced at the divisions of the circle of the 
 eccentric chuck adopted in the third and 
 fourth sets, but midway between those 
 divisions. 
 
12 7 
 
 SPECIMEN V. 
 
 —* »♦ — 
 
 This Specimen is composed of a num¬ 
 ber of concentric circles, and of arcs of 
 circles, which cross each other in the 
 manner represented in the accompanying 
 Plate (V). The concentric circles in¬ 
 crease in radius, in a uniform ratio from 
 the common centre: the arcs of circles 
 are all of the same measure, and are pro¬ 
 duced, not from the point of the com¬ 
 mon centre, hut from points equidistant 
 from it. 
 
 The tool to be used, to produce a piece 
 of Eccentric Turning corresponding with 
 this Specimen, is double angular No. 28, 
 and the slide rest is to be set at right 
 angles with the mandril of the lathe. 
 
 The work to be turned, being properly 
 fixed in the eccentric chuck, is to be 
 
128 
 
 brought to a plane and polished surface. 
 Then place an angular tool, No. 28, in 
 the slide rest, adjust its point, the slide 
 rest, and the eccentric chuck, to the com¬ 
 mon centre, and proceed to execute the 
 concentric circles. 
 
 III A CONCENTRIC CIRCLES. 
 
 Radius of the first circle equal to 1. 
 
 Radius of the second circle equal to 1-1. 
 
 Radius of the third circle equal to 2, &c. 
 
 To produce the radius for the first, or 
 internal circle, turn the slide rest screw 
 backwards one turn. Describe one cir¬ 
 cle. To produce the radius for the second 
 circle, increase the radius of the former 
 
129 
 
 by turning the slide rest screw backwards 
 half a turn. Describe another circle; and 
 so on, increasing the radius of each suc¬ 
 ceeding circle, by turning the slide rest 
 screw backwards half a turn, until eighty 
 circles are produced. 
 
 THE ARCS OF CIRCLES, OR CUREEL) 
 LINES. 
 
 Eccentricity equal to 30. 
 
 Radius equal to 30. 
 
 Measure of the arcs 9 equal to 
 
 These arcs of circles, or curved lines, 
 are to be cut with a similar angular tool, 
 
 9 The method of producing and measuring the 
 arcs, already described for Specimen IV, must be 
 attended to in this Specimen. Vide p. I 14. 
 
130 
 
 No. 28; and to the same depth as the con¬ 
 centric circles. Supposing the radius of 
 the exterior of the concentric circles to 
 have been equal to 40^ produce the 
 radius for the arcs; or curved lines; and 
 make it equal to 30; by turning the slide 
 rest screw forwards ten turns and a half. 
 Produce the eccentricity by turning the 
 slide screw of the eccentric chuck back¬ 
 wards thirty turns. Turn the mandril 
 pulley wheel; until the centre of the inte¬ 
 rior concentric circle coincides with the 
 point of the tool. Move the pulley wheel 
 forward; without letting the tool touch 
 the work; equal to an arc of ■*-§-*, and put 
 on a stop to prevent its moving beyond 
 that point. Move the pulley wheel back 
 again equal to an arc of and put on a 
 stop to prevent its moving any further 
 that way. 
 
 The tool being now applied to the sur¬ 
 face of the work; and the mandril pulley 
 wheel moved through the space thus li¬ 
 mited by the stops; an arc will be described 
 
13 ! 
 
 equal to -J-f; viz. an arc, which will begin 
 at a distance from the common centre 
 equal to and end at a distance from 
 the common centre equal to • 
 
 There are twelve sets of these arcs to be 
 produced and arranged in the following 
 manner; each set to consist of five arcs. 
 
 Set the circle of the eccentric chuck 
 (supposing it to be divided into 96,) at 
 division 96, and describe one arc at that 
 and at the four succeeding divisions: miss 
 three divisions, set the circle of the eccen¬ 
 tric chuck at division 8, and describe five 
 other arcs; and so on for the rest. The 
 divisions of the circle of the eccentric 
 chuck, at which the arcs in each set are 
 to be described, are as under. 
 
 1st set of arcs, at Nos. 96, 1, 2, 3, 4. 
 
 2nd do.8, 9, 10, 11, 12. 
 
 3rd do.16, 17, 18, 19, 20. 
 
 4th do. 24, 25, 26, 27, 28. 
 
 5th do. 32, 33, 34, 35, 36. 
 
 6th do. 40, 41, 42, 43, 44. 
 
133 
 
 SPECIMEN VI. 
 
 The accompanying Plate (VI) repre¬ 
 sents the manner in which the sets of 
 eccentric circles, and the sets of arcs, or 
 curved lines, are to be arranged in this 
 Specimen. The sets of circles are of dif¬ 
 ferent eccentricities and radii; and the 
 arcs, or curved lines, are all of the same 
 measure, and are produced from points 
 without, and equidistant from, the com¬ 
 mon centre. 
 
 To form a piece of Eccentric Circular 
 Turning, corresponding with this Speci¬ 
 men, use a double angular tool. No. 28, 
 and set the slide rest at right angles with 
 the mandril of the lathe. 
 
 The work to be turned is to be first 
 properly fixed in the eccentric chuck, and 
 brought to a plane and polished surface. 
 
134 
 
 Then place the angular tool; No. 28; in 
 the slide rest; adjust its point; the slide 
 rest; and the eccentric chuck; to the com¬ 
 mon centre; and proceed to execute the 
 arcs of circles; or curved lines. 
 
 THE ARCS , OR CURVED LINES. 
 
 Eccentricity equal to 12. 
 
 Radius equal to 12. 
 
 Measure of the arcs 
 
 Produce the eccentricity by turning the 
 slide screw of the eccentric chuck back¬ 
 wards twelve turns. Produce the radius 
 by turning the slide rest screw backwards 
 twelve turns. Then adjust the mandril 
 pulley wheel to the measure of the arcs of 
 circles; or curved lines; in the same man¬ 
 ner as directed for those in Specimen V. 
 
 These arcs of circles are; in all respects; 
 similar to those described in Specimen V; 
 
135 
 
 except in their dimensions; and are to be 
 described exactly in the same manner, at 
 the same divisions of the circle of the 
 eccentric chuck; at the same distance from 
 the common centre, and should be cut 
 sufficiently deep to bring the surface left 
 between them to an angle at top. * 
 
 CENTRE FIGURE, OR FIRST SET 
 OF CIRCLES. 
 
 Eccentricity equal to li. 
 Radius equal to 1. 
 
 Remove the stops from the mandril 
 pulley wheel, and continue with the an¬ 
 gular tool. No. 28. Produce the eccen¬ 
 tricity by turning the slide screw of the 
 eccentric chuck forwards ten turns and 
 three-quarters of a turn. Produce the 
 
136 
 
 radius by turning the slide rest screw 
 forwards eleven turns. Describe eight 
 equidistant circles, of the same depth as 
 the curved lines. 
 
 ' SECOND SET OF CIRCLES. 
 
 Eccentricity equal to 4|. 
 
 Radius equal to 17. 
 
 The same angular tool. No. 28, as be¬ 
 fore, and the circles are to be cut to a suf¬ 
 ficient depth to make the spaces, which 
 their intersection leaves, sharp at top. 
 Produce the eccentricity by turning the 
 slide screw of the eccentric chuck back¬ 
 wards three turns and one-eighth of a 
 turn. Produce the radius by turning the 
 slide rest screw backwards sixteen turns. 
 Describe twenty-four equidistant circles. 
 
137 
 
 THIRD SET OF CIRCLES. 
 
 Eccentricity equal to 30. 
 
 Radius equal to -§. 
 
 The circles in this and in the following 
 seven sets, are to be produced by the an¬ 
 gular tool. No. 28, and all cut to the 
 same depth as the second set. Produce 
 the eccentricity by turning the slide screw 
 of the eccentric chuck backwards twenty- 
 five turns and five-eighths of a turn. Pro¬ 
 duce the radius by turning the slide rest 
 screw forwards sixteen turns and a half. 
 Describe twelve equidistant circles. 
 
138 
 
 FOURTH SET OF CIRCLES. 
 
 Eccentricity equal to '29j. 
 
 Radius equal to 1. 
 
 The eccentricity is to be obtained by 
 turning the slide screw of the eccentric 
 chuck forwards half a turn. Obtain the 
 radius by turning the slide rest screw 
 backwards half a turn. Then describe 
 twelve equidistant circles, which are to 
 circumscribe those of the third set. 
 
139 
 
 FIFTH SET OF CIRCLES. 
 
 Eccentricity equal to 29. 
 
 Radius equal to If. 
 
 Produce the eccentricity by turning 
 the slide screw of the eccentric chuck for¬ 
 wards half a turn. Produce the radius 
 by turning the slide rest screw backwards 
 half a turn. Describe twelve equidistant 
 circles,, which are to circumscribe those 
 of the fourth set. 
 
140 
 
 SIXTH SET OF CIRCLES. 
 
 Eccentricity equal to 28f. 
 
 Radius equal to 2. 
 
 The eccentricity is to be produced by 
 turning the slide screw of the eccentric 
 chuck forwards half a turn. Produce 
 the radius by turning the slide rest screw 
 backwards half a turn. Describe twelve 
 equidistant circles, which are to circum¬ 
 scribe those of the fifth set. 
 
141 
 
 SEVENTH SET OF CIRCLES . 
 
 Eccentricity equal to 28. 
 
 Radius equal to 2\. 
 
 Produce the eccentricity by turning 
 the slide screw of the eccentric chuck for¬ 
 wards half a turn. Produce the radius 
 by turning the slide rest screw backwards 
 half a turn. Describe twelve equidistant 
 circles, which are to circumscribe those 
 of the sixth set. 
 
 L 
 
142 
 
 EIGHTH SET OF CIRCLES. 
 
 Eccentricity equal to TI\. 
 
 Radius equal to 3. 
 
 Produce the eccentricity by turning 
 the slide screw of the eccentric chuck 
 forwards half a turn. Produce the radius 
 by turning the slide rest screw backwards 
 half a turn. Describe twelve equidistant 
 circles^ which are to circumscribe those 
 of the seventh set. 
 
143 
 
 NINTH SET OF CIRCLES . 
 
 Eccentricity equal to 27. 
 
 Radius equal to . 
 
 Produce the eccentricity by turning 
 the slide screw of the eccentric chuck 
 forwards half a turn. The radius is to be 
 produced by turning the slide rest screw 
 backwards half a turn. Describe twelve 
 equidistant circles^ which are to circum¬ 
 scribe those of the eighth set. 
 
144 
 
 TENTH SET OF CIRCLES. 
 
 Eccentricity equal to 26j. 
 
 Radius equal to 4. 
 
 To obtain the eccentricity turn the slide 
 screw of the eccentric chuck backwards 
 half a turn; and produce the radius by 
 turning the slide rest screw forwards half 
 a turn. Then describe twelve equidis¬ 
 tant circles, which are to circumscribe 
 those of the ninth set, and complete the 
 figure. 
 
145 
 
 ELEVENTH SET OF CIRCLES. 
 
 Eccentricity equal to 23-£. 
 
 Radius equal to 1. 
 
 Proceed with the same angular tool. 
 No. 28; and cut the circles sufficiently 
 deep to make the spaces left between, or 
 within the circles, sharp at top: this set of 
 circles, as represented in the Plate (VI), 
 is produced by a division of the circle of 
 the eccentric chuck of 288. 
 
 Produce the eccentricity by turning 
 the slide screw of the eccentric chuck 
 forwards three turns. Produce the radius 
 by turning the slide rest screw forwards 
 three turns. Then set the circle of the 
 eccentric chuck (supposing it to be di¬ 
 vided into 288) at division 288: miss ten 
 divisions, set the circle of the eccentric 
 chuck at division 11, and describe one 
 
146 
 
 circle at that and at each of the two suc¬ 
 ceeding divisions, viz. at divisions 12 and 
 13: miss ten divisions, set the circle of 
 the eccentric chuck at division 24, and 
 describe one circle at that and at the two 
 succeeding divisions, viz. at divisions 25 
 and 26; and so on, missing ten divisions, 
 and describing three circles, until the 
 figure represented in the Plate (VI) be 
 completed. 
 
 The following may be substituted where 
 the circle of the eccentric chuck is di¬ 
 vided into only ninety-six. 
 
147 
 
 ELEVENTH SET OF CIRCLES. 
 
 ADAPTED TO A DIVISION OF NINETY-SIX. 
 
 Eccentricity of the uppermost circle equal to 25. 
 
 Eccentricity of the centre circle equal to 23|. 
 
 Eccentricity of the lowermost circle equal to 22. 
 
 Radius equal to 1. 
 
 Produce the eccentricity and radius, 
 for the centre circle, in the manner di¬ 
 rected for the set adapted to a division 
 of 288, and describe one circle at each 
 of the following divisions of the circle of 
 the eccentric chuck, viz. at 4, 12, 20, 
 28, 36, 44, 52, 60, 68, 76, 84, 92. 
 
 Obtain the eccentricity of the upper¬ 
 most circle by turning the slide screw of 
 the eccentric chuck backwards one turn 
 and half a turn; and, with the same ra¬ 
 dius, describe one circle at each of the 
 divisions of the circle of the eccentric 
 chuck, as before. Obtain the eccentri- 
 
148 
 
 city for the lowermost circle, by turning 
 the slide screw of the eccentric chuck 
 forwards three turns; and, with the same 
 radius as before, describe one circle at 
 each of the divisions of the circle of the 
 eccentric chuck before specified for the 
 centre circle. 
 
 TWELFTH SET OF CIRCLES. 
 
 Eccentricity equal to 34. 
 Radius equal to I. 
 
 Proceed with the same angular tool. 
 No. 28, and cut the circles sufficiently 
 deep to make their centres sharp at top: 
 the lowermost of the three circles are 
 those which are to be produced. Produce 
 the eccentricity by turning the slide screw 
 
149 
 
 of the eccentric chuck backwards twelve 
 turns. The radius remains as before. 
 Describe forty-eight equidistant circles; 
 one circle (supposing the circle of the 
 eccentric chuck to be divided into 96) at 
 each of the following divisions, viz. 2, 
 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 
 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 
 
 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 
 
 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 
 
 84, 86, 88, 90, 92, 94, 96. 
 
 THIRTEENTH SET OF CIRCLES. 
 
 Eccentricity equal to 37. 
 
 Radius equal to 1. 
 
 The circles now to be described are 
 the uppermost of the three circles, repre- 
 
150 
 
 sented in this illustration. Produce the 
 eccentricity by turning the slide screw 
 of the eccentric chuck backwards three 
 turns; and, with the same radius as be¬ 
 fore, describe one circle at each of the 
 divisions of the eccentric chuck named 
 for the twelfth set. 
 
 FOURTEENTH SET OF CIRCLES. 
 
 Eccentricity equal to 35|. 
 
 Radius equal to 1. 
 
 The circles now to be produced are 
 the centre of the three circles, represented 
 in this illustration. 
 
 Produce the eccentricity by turning 
 the slide screw of the eccentric chuck for¬ 
 wards one turn and a half; and, with the 
 
151 
 
 same radius as before,, describe one circle 
 (supposing the circle of the eccentric 
 chuck to be divided into ninety-six) at 
 each of the following divisions, viz. 1, 3, 
 5 , 7 , 9 , 11 , 13 , 15 , 17 , 19 , 21 , 23 , 
 25 , 27 , 29 , 31 , 33 , 35 , 37 , 39 , 41 , 43 , 
 
 45 , 47 , 49 , 51 , 53 , 55 , 57 , 59 , 61 , 63 , 
 
 65 , 67 , 69 , 71 , 73 , 75 , 77 , 79 , 81 , 83 , 
 
 85 , 87 , 89 , 91 , 93 , 95 . 
 
 The Specimens which follow, are illus¬ 
 trative of the powers of my Compound 
 Eccentric Chuck. 
 
152 
 
 SPECIMEN VII 
 
 —— 
 
 This Specimen is intended to illustrate 
 the power of the Chuck to produce 
 squares., oblong figures, and all figures 
 that result from the combination of two 
 right line motions, acting, alternately, at 
 right angles to each other. The piece of 
 wood, or other material to be worked 
 upon (in this case a piece of box wood 
 was used), being firmly chucked, was 
 faced down to a smooth surface and cor¬ 
 rect plane, with a tool fixed in the slide 
 rest. The slide plates were placed to tra¬ 
 verse at right angles, by adjusting the first 
 circular movement (the one next the lathe 
 head and between the two slide plates) for 
 the index to point to division marked 3. 
 The slide plate, next the lathe head, was 
 
153 
 
 then thrown out to half the extent of one 
 side of the square required, by turning the 
 slide plate screw d. d; and the second slide 
 plate was thrown out, to an equal extent, 
 by turning its screw the same number of 
 turns. The describing point, or cutting 
 tool, which had been previously fixed in 
 the slide rest, will now point to one of the 
 corners of the square, and must be adjust¬ 
 ed to cut a circle of the diameter and 
 depth required, and the lathe being moved 
 round, the circle at the corner of the square 
 was produced. The screw of the slide 
 plate next the lathe head was then turned 
 once round and another circle was cut; 
 and so on, until twenty-six circles were 
 cut, which completed one side of the 
 square. The second slide plate was then 
 worked, in the same manner as the other 
 had been, and another side of the square 
 was produced and made to consist, also, of 
 twenty-six circles. The slide plate next 
 the lathe head was then moved in the 
 same manner as before, but in the con- 
 
154 
 
 trary direction, and the third side of the 
 square was obtained; and the other slide 
 plate was then moved so as to form the 
 fourth side and complete the square. 
 
 The internal figure, consisting of large 
 circles, is effected on the same principle, 
 by the action of the two slide plates. 
 
 It is obvious that right line patterns, 
 similar to this Specimen and to others 
 which are to be seen in the title page, 
 cannot be obtained by any Chuck, unless 
 the slide plates throw out at both ends. 
 
OOOOOOOOOOOOOOCK 
 
SPECIMEN VIII 
 
 —■» ♦ ♦— 
 
 All figures similar to this Specimen re¬ 
 quire for their construction the whole of 
 the adjusting powers of the Compound 
 Chuck; and it will be found that it is not, 
 altogether, immaterial in what order they 
 are brought into action, to save labour 
 and effect correct execution. But, with¬ 
 out entering more particularly into the 
 various modes of proceeding, I will mere¬ 
 ly detail, in the present instance, the me¬ 
 thod I pursued in executing the Engrav- 
 ing. 
 
 The piece of wood on which the en¬ 
 graving was to be made, having been 
 firmly fixed in the chuck, was faced down 
 by a tool in the slide rest, to a smooth 
 surface and correct plane. The index to 
 
156 
 
 the circular movement next the lathe 
 head was adjusted to division marked 8, 
 and, thereby, the two slide plates (i. e. the 
 two right line movements) were placed at 
 an angle of 60 to each other. The index 
 to the second circular movement (being 
 that which is furthest from the lathe head) 
 was adjusted to division marked 12. The 
 slide plates were in their central position 
 on their respective bed plates, and the in¬ 
 dex to each of them pointed, consequently, 
 to division marked 0 of the scale on the 
 edge of their bed plates. 
 
 An angular sharp-pointed tool was now 
 fixed in the slide rest, and the point of it 
 was adjusted (at the centre of the man¬ 
 dril’s motion) to the radius of the circle 
 required: the lathe was then turned round 
 and the point of the tool described the 
 circle which is seen in the centre of the 
 engraving. The slide plate screw next 
 the lathe head was now turned twice 
 round to the left hand, thereby throwing 
 out the slide plate, from its central posi- 
 
157 
 
 tion„ to the extent of two divisions of the 
 scale on the edge of its bed plate: the 
 lathe was again turned round, and another 
 circle was described by the tool next to 
 the circle which had been made in the 
 centre. The two other circles, next to 
 the circle in the centre, were then des¬ 
 cribed, by means of adjusting the second 
 circular movement (£. e. that which is fur¬ 
 thest from the lathe head) and causing its 
 index to point to division marked 4, and 
 then to division 8. The slide plate screw, 
 next the lathe head, was again turned 
 twice round, in the same direction as 
 before, by which the slide plate became 
 thrown out to the extent of four divisions 
 of the scale on the edge of its bed plate; 
 and, then, three more circles were des¬ 
 cribed next to and in the same radial di¬ 
 rection with the last, by causing the index 
 to point to the same divisions as before, 
 viz. divisions marked 12, 4, and 8. The 
 slide plate was again thrown out to the 
 extent of wo more divisions, and three 
 
158 
 
 more circles were produced next to those 
 last described, and in the same radial lines 
 as before; and so on, throwing out the 
 slide plate to the extent of two turns of 
 its screw, making three circles each time, 
 and setting the circular movement for 
 each circle, so that the index pointed to 
 divisions marked 12, 4, and 8. This rou¬ 
 tine of adjusting the chuck was continued 
 until each of the three radial lines of cir¬ 
 cles were made to consist of sixteen circles 
 from the centre circle; and the slide plate 
 screw next the lathe head was not again 
 moved —its index remaining stationary, 
 pointing to the thirty-second division 
 from the division marked 0 of the scale 
 on the edge of the bed plate, during the 
 execution of the remaining part of the 
 engraving. The circular movement on 
 the second bed plate was now adjusted 
 for the index to point, in succession, to 
 divisions marked 2, 6, and 10, and a 
 circle was described at each of those 
 divisions. The screw of the second slide 
 
159 
 
 plate (the one furthest from the lathe 
 head) was now turned twice round, and 
 the slide plate was thereby thrown out 
 to the extent of two divisions from its 
 central position, in an angular lineal di¬ 
 rection to that in which the other slide 
 plate had been worked; and six circles 
 were described by setting the index of 
 the circular movement to point to the 
 divisions marked 2, 4, 6, 8, 10, and 12. 
 The same slide plate was again thrown 
 out to the extent of two divisions of the 
 scale on the edge of its bed plate, and 
 six more circles were described by set¬ 
 ting the circular movement to the divi¬ 
 sions marked 2, 4, 6, 8, 10, and 12, as 
 before. The slide plate screw was again 
 turned twice round, and six more circles 
 were described at the same divisions as 
 before; and so on until the engraving 
 was completed. 
 
160 
 
 SPECIMEN IX. 
 
 —— 
 
 This Specimen is intended to exhibit 
 the power possessed by a Compound Ec¬ 
 centric Chuck., of delineating or pointing 
 out the path of an Ellipsis; and it will 
 also serve as a practical illustration of 
 what has been said at pages 16 and 17. 
 Those who are conversant with the action 
 of Suardi’s Geometric Pen” will very 
 clearly see their way to the principle 
 which assigns this property to an eccen¬ 
 tric adjusting chuck ; and will, as readily, 
 trace it to the result of epicycloidal mo¬ 
 tion. It is well known that the periphery 
 and curvature of every ellipsis are limited 
 and defined by its diameters, and that the 
 ellipsis will be more or less eccentric in 
 proportion to the ratio in which its dia- 
 
_ -— .-.— - 
 
161 
 
 meters differ in length. If they differ in 
 the ratio of 100 to 1, that is, if the conju¬ 
 gate be only one-hundredth part as long 
 as the transverse, the ellipsis will be ex¬ 
 tremely eccentric, and the curvature of 
 its periphery will approach very closely 
 to a right line: if they differ in the ratio 
 of only 100 to 99, that is, if the conjugate 
 be only one-hundredth part shorter than 
 the transverse, then the ellipsis will ap¬ 
 proach very nearly to a circle. 
 
 In the case of the instrument before 
 us, its power of adjustment for the attain¬ 
 ment of the diameters of different ellipses 
 is very great. The adjustment, only, of 
 the slide plates to different eccentric posi¬ 
 tions, determine the diameters; and as the 
 plates can be adjusted to every possible 
 point of eccentricity, with regard to the 
 centre of the mandril’s motion and to 
 each other, every variety of the ellipsis, 
 from the right line to the circle, may be 
 perfectly traced. The adjustments of the 
 chuck may be differently combined, and 
 
162 
 
 brought into action under different ar¬ 
 rangements, without causing any variation 
 in the results; but, on the present occa¬ 
 sion, I will confine myself to the method I 
 pursued in working the chuck, to produce 
 this Specimen, which, I think, will be 
 found both ready and convenient; and if 
 the following general rules be borne in 
 mind and be strictly attended to, not any 
 difficulty will be experienced in obtaining 
 elliptical patterns of any eccentricity and 
 size, that may be required, within the limit 
 of the action of the chuck and lathe. 
 
 THE RULES. 
 
 1st. Elliptical patterns require the action 
 of both the slide plates; and the slide 
 plate next the lathe head is invariably 
 thrown out to a greater extent than 
 the other slide plate. 
 
 2nd. Both the circular movements are in¬ 
 variably brought into action, and the 
 velocity of their adjustment must be in 
 the ratio of 2 to 1 in contrary direc- 
 
163 
 
 tions ; that is, if the circular movement 
 next the lathe head be moved 2 divi¬ 
 sions at each adjustment, the other cir¬ 
 cular movement must be moved only 1 
 division at each adjustment, in the con¬ 
 trary direction. If the first be moved 
 at the rate of 4 divisions, the second 
 must be moved at the rate of 2 divi 
 sions; and so on. 
 
 3rd. The semi-transverse diameter is, in¬ 
 variably, equal to the extent of the two 
 eccentric adjustments of the slide plates, 
 added together. For example: 
 
 If the slide plate next the lathe head 
 be adjusted to the extent of 20 turns of 
 the screw, and the other slide plate to 
 the extent of 10 turns, the semi-trans- 
 verse will be equal to 30 turns of the 
 screw. 
 
 4th. The semi-conjugate diameter is al¬ 
 ways equal to the difference between 
 the extent of the two eccentric adjust¬ 
 ments. For example: 
 
 If one slide plate be thrown out to 
 
164 
 
 the extent of 20 turns of the screw, and 
 the other slide plate to the extent of 10 
 turns of the screw, the semi-conjugate 
 will be equal to 10 turns of the screw. 
 
 I will now explain, with reference to 
 the foregoing rules, the adjustments of 
 the chuck I adopted in executing that 
 portion of the Specimen IX which consists 
 of a set of forty-eight consecutive white 
 lines surrounding black dots, through the 
 centre of which the path of a true ellipsis 
 lies. 10 At page 17 I explained the man¬ 
 ner of tracing an ellipsis, the diameters of 
 which were to be in the ratio of 3 to 2 ; 
 
 In All curves traced on the principle here des¬ 
 cribed will be true, in every point, to that particular 
 section of the Cone which is known and distinguish¬ 
 ed by English mathematicians, as the Ellipsis °f 
 Apollonius; and there is no method, by means of 
 points, by which that section of the Cone can be 
 more easily and correctly delineated. Figures, also, 
 of a true oval shape may be traced by means of this 
 Chuck, as perfectly as by any method heretofore 
 suggested by the mathematician ; and in exemplifi- 
 
165 
 
 and in the case of the Specimen before us 
 the diameters are in the ratio of 5 to 3. 
 
 The piece of wood on which the en¬ 
 graving was executed, having been firmly 
 fixed in the chuck, the face of it was 
 turned over by a tool in the slide rest, and 
 brought to a smooth surface and true 
 plane. The slide plate next the lathe 
 head (rule 1) was thrown out of its central 
 position and adjusted by turning its screw 
 round 24 turns; and the other slide plate 
 was adjusted by turning its screw 6 turns, 
 and throwing the slide plate out in the same 
 lineal direction in which the other slide 
 plate had been thrown out. Now 6 added 
 
 cation of its possessing this power, I have executed 
 with it and introduced two Specimens, No. XIII 
 and No. XIV. 
 
 By different combinations, arrangements, and ad¬ 
 justments of the Chuck, other patterns may be pro¬ 
 duced in endless variety; and, in proof of it, the 
 engravings in the title page will serve as a few ex¬ 
 amples, I will also give a few more; but, with re¬ 
 gard to these and the oval figures, it is not my in¬ 
 tention to enter into any detail of the adjustments 
 of the Chuck by which they were produced. 
 
166 
 
 to 24 equals 30 (3rd rule), and thereby 
 the semi-transverse became equal to 30 
 turns of the screw, and the whole trans¬ 
 verse to 60 turns. The difference between 
 the two adjustments (24 and 6) is 18, and 
 therefore (4th rule) the semi-conjugate 
 was equal to 18 and the whole conjugate 
 to 36 turns of the slide plate screw : thus 
 the slide plates of the chuck were adjusted 
 to cause the length of the diameters to be 
 in the ratio of 60 to 36, or as 5 to 3. 
 
 The index of each of the circular move¬ 
 ments pointed to division marked 12, and 
 a pointed tool being fixed in the slide rest 
 and adjusted to the radius of the circle 
 required, the lathe was turned round and 
 a circle was described at one of the ex¬ 
 treme ends of the transverse diameter. 
 The circular movement, next the lathe 
 head (2nd rule), was advanced 4 divisions, 
 and the other circular movement was ad¬ 
 vanced 2 divisions, in the contrary direc¬ 
 tion, and another circle was described. 
 The circular movement next the lathe 
 
16? 
 
 head was again advanced 4 divisions, and 
 the other circular movement was advanced 
 two divisions, as before, and another cir¬ 
 cle was described; and so on until the 
 whole forty-eight circles were produced, 
 and the Specimen, so far, finished. 
 
 The diameters of the ellipsis mentioned 
 at page 17 were in the ratio of 3 to 2. 
 The diameters of the Specimen I have just 
 described are in the ratio of 5 to 3; and 
 I will now give the adjustments of the slide 
 plates of the chuck, by which other ellip¬ 
 ses may be obtained of various diameters. 
 
 The eccentric adjustment 
 of the Slide Plates. 
 
 The length of the Diame¬ 
 ters of the Ellipses. 
 
 The ratio of differ¬ 
 ence between the 
 length of the Dia¬ 
 meters. 
 
 Slide Plate 
 next the Lathe 
 Plead. 
 
 The Second 
 Slide Plate. 
 
 Transverse 
 
 Diameter. 
 
 Conjugate 
 
 Diameter. 
 
 <y 
 
 <n CC 
 
 > b£ 
 
 No. of turns 
 of the screw. 
 
 No. of turns 
 of the screw. 
 
 No. of turns 
 of the screw. 
 
 No. of turns 
 of the screw. 
 
 1 ¥ 
 
 ^ 0 
 
 54 .. 
 
 .. 6 .. 
 
 .. 60.. 
 
 .. 48.. 
 
 5 to 4 
 
 33 .. 
 
 .. 3 .. 
 
 .. 36.. 
 
 .. 30.. 
 
 6—5 
 
 36 .. 
 
 .. 6 .. 
 
 .. 42.. 
 
 .. 30.. 
 
 7—5 
 
 69 .. 
 
 .. 3 .. 
 
 .. 72.. 
 
 .. 66.. 
 
 12 — 11 
 
 58|.. 
 
 .. If. 
 
 .. 60.. 
 
 .. 57.. 
 
 20—19 
 
 298|.. 
 
 .. 1|.. 
 
 ..300.. 
 
 ..297.. 
 
 100 —99 
 
 I51|. . 
 
 . 148|.. 
 
 ..300.. 
 
 .. 3.. 
 
 100 — 1 
 
 N 
 
168 
 
 SPECIMEN X. 
 
 —— 
 
 A line passed through the centres of 
 the circles which form this Specimen,, will 
 trace the path of a true Epicycloidal 
 curve; and one of the names which have 
 been assigned to this curve is “ The Snail 
 of Pascal.” The following arrangement 
 of the chuck will produce it. 
 
 The piece of wood, on which the en¬ 
 graving was executed, having been firmly 
 fixed in the chuck, the face of it was 
 turned down to a true plane and smooth 
 surface; and a pointed tool was fixed in 
 the slide rest and was adjusted to the ra¬ 
 dius of the circles, 96 of which form the 
 pattern. The circular movements were 
 adjusted to cause each index to point to 
 the division marked 12. The slide plate 
 
169 
 
 next the lathe head was thrown out to the 
 extent of sixteen turns of its screw. The 
 other slide plate was thrown out, in the 
 same direction, to the extent of twelve 
 turns of its screw. A circle was then des¬ 
 cribed. The circular movements were 
 both moved, in the same direction, one 
 division (equal to -5V part of the whole cir¬ 
 cle) and another circle was described; and 
 so on, moving each circle one division, in 
 the same direction, and describing a circle 
 each time, until the figure was completed. 
 
SPECIMEN XI 
 
 A line passed through the centres of 
 the circles which form this Specimen will 
 trace the path of a true Epicycloidal 
 curve; and this curve comprehends the 
 curve of M. Carre. The arrangements of 
 the chuck and slide rest to produce it, 
 are as under. 
 
 The piece of wood, on which the en¬ 
 graving was executed, was firmly fixed in 
 the chuck, and the face of it was turned 
 down to a true plane and smooth surface. 
 A pointed tool was then fixed in the slide 
 rest and adjusted to the radius of the larg¬ 
 est of the forty-eight circles which form 
 the pattern. The circular movements were 
 adjusted for the index of each to point to 
 the division marked 12. The slide plate 
 
171 
 
 next the lathe head was thrown out to the 
 extent of eight turns of its screw. The 
 other slide plate was thrown out, in the 
 same direction, to the extent of sixteen 
 turns of its screw ; and a circle was then 
 described. The circular movements were 
 both moved in the same direction, two 
 divisions, (equal to — parts of the whole 
 circle) and the radius of the circle was 
 decreased, by turning the slide rest screw 
 one-twelfth part round, and then ano¬ 
 ther circle was described. The circular 
 movements were again moved two divi¬ 
 sions each, in the same direction; and 
 the radius of the circle was further de¬ 
 creased by turning the slide rest screw 
 another twelfth part round, and another 
 circle was described. And so on, moving 
 the circles two divisions, and decreasing 
 the radius of the circle each time by turn¬ 
 ing the slide rest screw one-twelfth of a 
 turn, until the index to each circle pointed 
 to division marked 6, when the figure will 
 have progressed to the smallest of the 48 
 
circles; and, then, the radius of the re¬ 
 maining circles is to be increased, at each 
 adjustment of the circular movements, by 
 turning the slide rest screw one-twelfth 
 part of a turn, in the contrary direction, 
 until the index to each circular movement 
 again pointed to division marked 12, when 
 the pattern was completed. 
 
173 
 
 SPECIMEN XII. 
 
 —» — 
 
 A line passed through the centres of 
 the circles which form this Specimen will 
 trace the path of a true Epicycloidal 
 curve; and the arrangements of the chuck, 
 for producing the outermost set of circles, 
 are as under. 
 
 The piece of wood on which the en¬ 
 graving was executed, was firmly fixed in 
 the chuck, and the face of it was turned 
 down to a true plane and smooth surface. 
 A pointed tool was then fixed in the slide 
 rest and adjusted to the radius of the small 
 circles, ninety-six of which form the pat¬ 
 tern. The circular movements were ad¬ 
 justed for the index, to each of them, to 
 point to division marked 12. The slide 
 plate next the lathe head was thrown out 
 
174 
 
 to the extent of twenty-two turns of its 
 screw; and the other slide plate was 
 thrown out to the extent of five turns of 
 its screw. A circle was then described. 
 The circular movement next the lathe 
 head was then moved two divisions; and 
 the other circular movement was moved 
 one division,, in the same direction; and 
 then another circle was described: and 
 so on, moving the circular movement 
 next the lathe head two divisions and 
 the other circular movement one division, 
 and describing a circle each time,, until 
 the whole ninety-six circles were com¬ 
 pleted. 
 
 The internal curve is of the same cha¬ 
 racter and proportionate to the other, and 
 is composed of the same number of circles 
 of larger diameter. 
 
175 
 
 CONCLUSION. 
 
 The Specimens which I have now given 
 will have developped, in some degree, the 
 system by which various geometrical fi¬ 
 gures may be delineated by combining a 
 right line with a circular adjustment; and 
 it is quite obvious that the path of every 
 possible curve and figure may be mathe¬ 
 matically traced by means of such an in¬ 
 strument as a Compound Eccentric Chuck. 
 The Geometric Pen, invented by The 
 Count Suardi, is capable of delineating an 
 infinite variety of curves, by the continu¬ 
 ous motion of a point acting against a fixed 
 surface. My Compound Eccentric Chuck 
 is capable of delineating and recording 
 the path of the same curves, by means of 
 dots and circles; and the Specimens I have 
 
176 
 
 given will shew, though to a very limited 
 extent, that it possesses this power. I 
 will only add, that it will afford me plea¬ 
 sure to explain my Chuck to any Gen¬ 
 tleman, who is an Amateur Turner, and 
 who may be desirous of adding to his 
 Turning Apparatus such an instrument as 
 my Compound Eccentric Chuck. Any ap¬ 
 plication addressed to me shall be imme¬ 
 diately attended to, and I will appoint a 
 time when I will be at home to shew the 
 Chuck. 
 
 J. H. Ibbetson. 
 
 3, Brompton Grove, 
 
 Knightsbridge. 
 
SUPPLEMENTARY SPECIMENS 
 
 Referred to in the Note at page 165. 
 
 SiPECMIEM MT 
 

»