REESE LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Deceived J^<su~< , i$Q9 
 
 
 
 */// } (n 3. ri y< c" \// ) 
 
 I U LI U 1? 
 
 Accession No. 
 
3obn Mile? & Sons. 
 
 THE COFFER-DAM PROCESS 
 FOR PIERS. 
 
 FOWLER, 
 
THE 
 
 COFFER-DAM PROCESS 
 FOR PIERS. 
 
 PRACTICAL EXAMPLES FROM 
 ACTUAL WORK. 
 
 CHARLES EVAN FOWLER, 
 
 31 ember American Society of Civil Engineers , 
 Bridge Engineer. 
 
 " Much of the success of any one in any kind of work, and especially in 
 work subject to the peculiar difficulties of that we are considering, depends 
 upon the spirit in which it is undertaken. "-ARTHUR MELLEN WELLINGTON. 
 
 FIRST EDITION. 
 FIRST THOUSAND. 
 
 NEW YORK: 
 
 JOHN WILEY & SONS. 
 
 LONDON: CHAPMAN & HALL, LIMITED. 
 1898. 
 
Copyright, 1898, 
 
 BY 
 C. E. FOWLER. 
 
 6 2. 
 
 ROBERT DRUMMOND, ROBERT^DRUMMOND, 
 
 P. H. RANCKPUB. CO., 444 PBARL STREET, 
 
 Electrotypes. 
 
 NEW YORK. 
 
INTRODUCTION. 
 
 THE greater part of foundation work is of an ordinary character. And 
 while difficult foundations have been quite fully treated by engineering writers, 
 ordinary ones have too often been passed over with mere mention, or treated in 
 such a general way that the information proves of little value in actual practice. 
 
 Many valuable examples of work of this character have been described in 
 current engineering literature, and it is hoped that by bringing them together 
 a real service will be rendered the profession, as well as much valuable time 
 be saved for considering other and equally important problems. 
 
 The history of the coffer-dam process would seem to indicate that engineers 
 of nearly a century ago gave more consideration to the smaller problems than 
 the engineer of to-day, who has apparently passed to the consideration of the 
 larger and of course more interesting ones. 
 
 That this is deplorable, is proven by the many cases where money has been 
 wasted in the after effort to make good the mistakes that have become appar- 
 ent where cheap construction of coffer-dams has been resorted to. The saving 
 in original cost, as between an indefensible method and a defensible one, is 
 often so small as to seem absurd when it has become necessary to make large 
 expenditures to rectify the errors. 
 
 Errors of judgment are more easily excusable with regard to foundations 
 than with any other class of construction, but where definite limits can be set, 
 economy will result by keeping as closely as possible within them. 
 
 Reference is made in the following pages to the splendid construction of 
 foundations by the Romans, where they could be built outside the water. 
 The Pont du Gard, illustrated in the frontispiece, is the most notable example 
 of this extant. It is interesting also as indicating their knowledge of the better 
 form of piers and methods of arch construction. 
 
 Although constructed during the reign of the Emperor Augustus, at the 
 beginning of the Christian era, it is in a remarkable state of preservation, aside 
 from repairs that have been made from time to time. 
 
 Probably the earliest recorded examples of the use of coffer-dams which 
 give details of construction are those constructed under the engineers of the 
 Fonts et Chaussees. 
 
IV IN TROD UCTION. 
 
 Those built under Perronet at the bridge of Orleans were large and exten- 
 sive, and references made to the pile drivers and the pumps used on the work, 
 serve to illustrate the great amount of attention paid to planning the details of 
 construction. 
 
 The same engineer completed the piers of the bridge at Mantes, where the 
 coffer-dams were constructed to enclose both the abutment -and the nearest 
 pier within one dam, making the dimensions about 150 feet by 200 feet in the 
 extreme! 
 
 Hardly less notable were the coffer-dams at Neuilly, where the interiors 
 were so large, that the excavation did not approach near the inside wall of the 
 dam. 
 
 All of these were constructed prior to the year 1775, and the details as 
 shown in the elaborate drawings are of much interest to the engineer engaged 
 on similar works. 
 
 The coffer-dams constructed about 1825 by Rennie on the new London 
 bridge were the prototypes of those used at Buda-Pesth, but were elliptical in 
 form. They were designed with as much care, apparently, as any other feature 
 of the bridge, and from the fact that the water was pumped to twenty-nine feet 
 below low water and the work found tight, the details must have been very care- 
 fully executed. 
 
 However great the amount of care bestowed, there will be cases undoubtedly 
 where the difficulties cannot be foreseen, and it will become necessary to adopt 
 some of the many expedients cited to overcome them ; or they might better be 
 employed from the start, where any suspicion is had that trouble may ensue. 
 
 The question as to whether it will be best to use a crib or a sheet-pile cof- 
 fer-dam will most always be decided by the character of the bottom, the loca- 
 tion, and the character of the foundation to be built. It is advisable, whichever 
 type is selected, to make the size large enough, so that the excavation may be 
 completed without approaching too close to the inside wall of the dam, and so 
 that plenty of room may be had for the laying of the foundation courses. 
 
 The unit stress adopted for timber construction is believed to be as large as 
 will give good results in the majority of cases, both on account of the possibil- 
 ity of the construction having to undergo more severe usage than is expected, 
 and on account of the grade of timber which is most often made use of for tem- 
 porary works. 
 
 Where it is permissible from the standpoint of true economy, it is believed 
 that steel construction will commend itself for use. In most localities it will 
 not be long until metal construction will be found cheaper than timber for build- 
 ing coffer-dams, and in many places this is already true. 
 
 A great mistake is made, in nearly nine cases out of ten, by trying to use old 
 machinery, such as hoisting engines, pumps, and the like, which are ill adapted to 
 the purposes tor which they are intended, on account of lack of capacity and 
 only too often on account of having outgrown their usefulness. 
 
IN TROD UC TION. V 
 
 The engineer would avoid many unpleasant situations by demanding that a 
 proper outfit be provided, and in the end gain the thanks of the contractor for 
 increased profits. 
 
 Extended acquaintance with Portland cement is increasing the use of con- 
 crete in construction, and this is a great gain for the engineer, as it is not only 
 superior to much stone that is used, but is better adapted to use in difficult 
 situations. It also lends itself more readily to use for ornamental details in pier 
 construction. That truly ornamental piers are not, however, those with need- 
 less and frivolous details, has been clearly set forth in the last article. Sim- 
 plicity and beauty are near relatives. 
 
 The best locations cannot always be chosen for piers, but careful examina- 
 tion will often be the means by which bad locations may be avoided. 
 
 The methods for determining the economic division of a given crossing of a 
 river, have not come into general use, probably on account of lack of easy ap- 
 plication. The method given is an accurate one and very simple to use, es- 
 pecially if the results are tabulated for a given loading. 
 
TABLE OF CONTENTS. 
 
 ARTICLE I. 
 
 HI STL 1RICA L DK I 'EL O/>MEN T. 
 
 PAGE 
 
 Relation of Foundation to Bridge Design. Roman and Other Ancient Founda- 
 tions. Bridge at Shuster, Persia. Roman Arch at Trezzo. Four Ancient 
 Methods for Foundations. Method of Open Caissons. Method with Piles and 
 Concrete Capping. Method of Encaissement. Method of Coffer-dams. 
 Caesar's Bridge over the Rhine. Pneumatic Caissons and Coffer-dams appli- 
 cable to Different Cases. Origin of Coffer-dams and Primitive Types. The 
 Hutcheson Bridge at Glasgow. Robert Stevenson's Specifications for Coffer- 
 dams on Hutcheson Bridge. Old Directions for Triple-puddle Coffer-dam in 
 Forty Feet ( !) of Tide-water. W. Tierney Clark's Account of the Great Coffer- 
 dams for the Buda-Pesth Suspension Bridge. Character of Puddle used. Class 
 of Work to which Coffer-dams should be applied. Value of Actual Examples.. i 
 
 ARTICLE II. 
 
 CONSTRUCTION AND PRACTICE. CAY/. 1 COFFER-DAMS. 
 
 Definition of Coffer-dam. Simple Clay Bank. Drag Scraper for removing Soft 
 Bottom. Excavating Spoon. Larger Dredges mentioned. Crib and Embank- 
 ment used on Chanoine Dams on Great Kanawah River. Improvised Na- 
 smyth Sheet-pile Hammer. Failure on Ohio River because of Porous Bottom. 
 Crib Coffer-dam with Puddle Chamber, C., B. & Q. R. R. Cribs without 
 Puddle Chambers, Can. Pac. Ry. Cribs of Old Plank, Santa Fe Ry. Crib for 
 Arkansas River, St. L. and S. F. Ry. Sheet Piles used on Santa Fe. Sheet 
 Piles used on Union Pacific Ry. Coffer-dam on Grillage, Union Pacific Ry. 
 Circular Coffer-dam of Staves at Fort Madison, la. Circular Coffer-dam 
 pailure at Walnut St., Phila. Probable Cause of Failure. Form of Construc- 
 tion to adopt. Use of Puddle. Cutwaters. True Economy of Construction. . 13 
 
 ARTICLE III. 
 
 CONSTRUCTION AND PRACTICE. CRIBS AND CANT AS. 
 
 Stopping Leaks. Canvas Bulkhead at Keokuk, Iowa. Canvas Funnel for Springs. 
 Anchoring Cribs and Crib Coffer-dam at St. Louis. Timber Casings cov- 
 
 vii 
 
Viil TABLE OF CONTENTS. 
 
 PAGE 
 
 ered with Canvas, Melbourne. Strength of Water-soaked Timber. Polygonal 
 Crib for Harlem Ship Canal Pivot Pier. Polygonal Crib for Arthur Kill 
 Bridge. Octagonal Crib, Coteau Bridge 28 
 
 ARTICLE IV. 
 
 PILE DRIl'ING AND SHEET PILES. 
 
 Historical Forms of Pile Drivers. Simple Sheet-pile Driver. Large Pile-driving 
 Derricks. Machinery for Pile Driving. Cost of Outfits. Nasmyth Hammers 
 of Various Types. Loads on Guide and Foundation Piles. Pulling Piles and 
 sawing off under Water. Forms of Sheet Piles. Wakefield Sheet Piling. 
 Shoes for Sheet Piling. 40 
 
 ARTICLE V. 
 
 CONSTRUCTION WITH SHEET PILES, 
 
 Water and Puddle Pressure. Calculation of Sheet Piling. Size of Wales and 
 Struts. Width of Puddle Chambers. Guide Piles and Guides. Ann Arbor 
 Sheet-pile and Puddle Coffer-dam, M. C. Ry. Failure with Sheet Piles at 
 Arthur Kill Bridge. Successful Method adopted. Sewer Coffer-dam for 
 Boston Sewerage System. Wakefield Sheet Piling. Harper's Ferry Coffer- 
 dam. Momence, 111., Coffer-dam, C. & E. I. Ry. Sheet Piling for Charles- 
 town Bridge Piers. Polygonal Sheet-pile Reservoir Coffer-dam at Fort 
 Monroe, Va 54 
 
 ARTICLE VI. 
 
 CONSTRUCTION WITH SHEET PILES. 
 
 Combinations of Various Forms of Sheet Piles. Sheet-pile and Puddle Coffer- 
 dam, Walnut Street Bridge, Chattanooga. Framing of Cumberland, Md., 
 Coffer-dam. Sandy Lake Coffer-dam and Pile-driving Plant. Driving Sheet 
 Piles with Water Jet. Use of Sheet Piling on Foundations of Main Street 
 Bridge, Little Rock. Concrete Piers at Little Rock. Removal of Old Pier at 
 Stettin, Germany. Removal and Repair of Pier in Coosa River, Alabama. 
 Floating Coffer-dam for P. & R. R. R. Bridge over the Schuylkill. Use of Six- 
 inch Sheet Piles at St. Helier, Jersey. Stock Rammer to stop Leaks. Single- 
 pile Coffer-dams, Putney Bridge. Twelve-inch Sheet Piling, Victoria Docks. 
 Tongue and Groove Sheet Piling, Topeka, Kansas. Use of Dredging Pump 
 at Topeka - 66 
 
 ARTICLE VII. 
 
 METAL CONSTRUCTION. 
 
 Thin Steel Shells. Hawkesbury Oblong Metal Piers. Vertical and Inclined Cut- 
 ting Edges. Water-tight Construction. Pivot Pier of Clustered Cylinders. 
 
TABLE OF CONTENTS. ix 
 
 PAGE 
 
 Double-cylinder Pier. Russian Ornamental Cylinder Piers. Lighthouse 
 Cylinders. Calculation of Thin Metal Cylinders. Forth Bridge Metal Coffer- 
 dams. Forth Bridge Circular Granite Piers. Combined Metal Coffer-dam and 
 Pier Base. Metal Sheet Piles 80 
 
 ARTICLE VIII. 
 
 PUMPING AND DREDGING. 
 
 Amount of Pumping indicates Success. Bascule for Pumping. Chapelet for 
 Pumping. Bucket Wheel used at Neuilly. BQX Lift Pump. Metal Lift Pump. 
 Diaphragm Pump. Steam Siphons. Van Duzen Jet. Lansdell Siphon. 
 Pulsometer Steam Pump. Maslin Automatic Vacuum Pump. Comparative 
 Efficiency of Centrifugal and Reciprocating Pumps. Tests of Centrifugal 
 Pumps. Direct-Connected Engine and Centrifugal Pumps. Use of Electric 
 Power. Suction-pipe Details. Type and Capacity of Pump. Methods of 
 Priming. Double-suction Pumps. Dredging Pumps. Clam shell and Grapple 
 Dredges. Sand Diggers and. Elevator Dredges. Dipper Dredges. Cost of 
 Dredging 9: 
 
 ARTICLE IX. 
 
 THE FOUND A TION. 
 
 Character of Foundation. ^-Kind of Bottom. Soft Bottom. Pile Foundation. 
 Soft Material overlying Hard Bottom. Clean Smooth Rock. Sloping Rock. 
 Rough Rock. Concrete Levelling Course. Concreting under Water. Mono- 
 lithic Concrete Piers. Concrete Piers at Red River. Monolithic Concrete on 
 Illinois and Mississippi Canal. Requirements for Good Concrete. Compo- 
 sition of Concrete. Contractor's Plant. Cableways 106 
 
 ARTICLE X. 
 
 LOCATION AND DESIGN OF PIERS. 
 
 Location at Fixed Site. Location at New Site. Government Requirements. 
 Examination of Site. Test-boring Apparatus. Mississippi River Commission 
 Boring Device. Economical Length of Spans. Ottewell's Formula for Eco- 
 nomic Span. Morison's Design for Piers. Omaha Union Pacific Piers. Rus- 
 sian Piers. Obstruction caused by Piers. Cresy's Experiments on the 
 Obstruction caused by Piers. Correlation of Theoretical Form and Archi- 
 tectural Design 120 
 
TABLE OF COFFER-DAMS.- 
 
 , & 
 
 X 
 
 River and Location. 
 
 C-en,. *' 
 
 Character of Bottom. 
 
 i 5 
 
 2 6 
 
 3 8 
 4 9 
 5 U 
 6 15 
 
 7 17 
 
 S 18 
 9 18 
 10 18 
 
 II 20 
 
 12 2O 
 I 3 20 
 14 20 
 15 20 
 I ( ) 2O 
 17 20 
 IS 2 4 
 I 9 3 
 20 72 
 
 21 33 
 
 22 36 
 
 23 38 
 24 39 
 25 59 
 2t> 60 
 27 60 
 28 62 
 29 62 
 30 63 
 3i ( >3 
 32 64 
 33 66 
 34 67 
 35 67 
 36 70 
 37 72 
 3S ; 74 
 39 74 
 40177 
 -41 77 
 42 77 
 43 78 
 44|86 
 
 River 200 feet wide Ohio 
 
 None. 12' -f 
 Slight. 9' + 
 Tide. 40' 
 Swift. 54' 
 Swift. 34' - 
 Moderate. 20' -f- 
 Moderate. 6' + 
 Swift. 20' -i 
 Swift. 21' - 
 None. 15' -)- 
 Moderate. 7' -j- 
 Moderate. 6' + 
 Moderate. 6' -+- 
 Moderate. 7' -j- 
 Moderate. 6' -j- 
 Moderate. 6' 
 Swift. 19' 
 Moderate. Deep. 
 None. 12' -f- 
 Swift. ; 22' 
 Swift. 15' 
 Moderate. 25' 
 Tide. 28' 
 Moderate. ! 28' 
 Moderate. 6' -f- 
 Tide. 30' - 
 Tide. 10' 
 Moderate. 7' 
 Moderate. 6' -+- 
 Swift. 6' + 
 Tide. 6| + 
 None. 20' 
 Swift. 
 Moderate. 10' -(- 
 Swift. 8' -f 
 Moderate. 6' -\- 
 Moderate. 25' -j- 
 Moderate 10' -j- 
 Swift. 8' + 
 Tide. 13' + 
 Moderate. Deep. 
 Tide. 35' 
 Swift. 6' + 
 Tide. 15' + 
 
 Cemented gravel. 
 Gravel, sand, mud. 
 Sand & gravel over clay. 
 Gravel over clay. 
 Gravel over hardpan. 
 Gravel. 
 Soft. 
 Rock. 
 Rock. 
 Sand. 
 Gravel over rock. 
 Soft. 
 Sandy. 
 Gravel over soapstone. 
 Rock. 
 Soft. 
 Soft. 
 Mud over rock. 
 Rock. 
 Rock. 
 Rock. 
 Rock. 
 Clay over rock. 
 Rock. 
 Gravel. 
 Mud and clay. 
 Sand and gravel. 
 Sand and mud. 
 Rock. 
 Rock. 
 Soft. 
 Soft. 
 Gravel over rock. 
 Sand over hardpan. 
 Sand. 
 Sand. 
 Clay. 
 Gravel over rock. 
 Rock. 
 Earth over rock. 
 Mud. 
 Rock. 
 Sand. 
 Rock. 
 
 
 
 Danube at Bud a Pesth . - 
 
 
 
 Western part United States 
 
 
 
 
 
 Western part United States 
 
 Western part United States 
 
 Western part United States 
 
 Payette and Weiser, Union Pacific. 
 Mississippi Fort Madison 
 
 Schuylkill near Philadelphia, Pa... 
 U S Canal Keokuk 
 
 
 
 
 Arthur Kill Bridge 
 
 Coteau Bridge C Pac Ry 
 
 Ann Arbor, Mich., M. C. Ry 
 Arthur Kill Bridge 
 
 Boston Harbor sewer 
 
 Illinois River La Grange 
 
 Kankakee at Alomence 
 
 Potomac at Harper's Ferry 
 C harlestown Bridge Boston 
 
 
 
 Cumberland Md 
 
 Mississippi Sandy Lake 
 
 Arkansas Little Rock . . 
 
 Parnitz, Stettin, Germany 
 Coosa, Gadsden, Ala 
 Schuylkill P & R R R 
 
 St. Helier Bridge, Jersey, Eng. . . . 
 Thames at Putney 
 
 Victoria (B C ) Docks 
 
 Kaw at Topeka 
 
 
 
SYNOPSIS OF EXAMPLES. 
 
 
 
 
 
 
 Form of Construction. 
 
 Inside 
 Dimensions. 
 
 Kind of Puddle. 'Vuddle* 8 
 
 Remarks. 
 
 i ' 
 
 Earth bank. 
 
 TO' X 60'? 
 
 Clay and gravel. 5' 4- 
 
 No leaks. 
 
 5 
 
 Sheet piles. 
 
 20' X 58'? 
 
 Clay. 3' 
 
 
 6 2 
 
 Sheet piles. 
 
 Large. 
 
 Clay, sand &. gravel. 3~6' 
 
 Typical. 
 
 8 3 
 
 Sheet piles. 
 
 72' X 136' + 
 
 Clay and gravel. 2-5' 
 
 Difficult. 9 4 
 
 Earth bank. 
 
 90' X 33' 
 
 Clay and gravel. 19' 4~ 
 
 J 4 5 
 
 Earth bank.? 
 
 200' X 600' 
 
 Clay and gravel. 
 
 Failed. 15 6 
 
 Crib. 
 
 Medium. 
 
 Clay. 3' 4- 
 
 17 7 
 
 Crib, single. 
 
 24' X 43' 
 
 Concrete inside. 
 
 
 18 3 
 
 Crib, single. 
 
 1 6' X 34' 
 
 Concrete inside. 
 
 
 IS Q 
 
 Crib, single. 
 
 17' X 43' 
 
 Clay outside. 
 
 
 Special. 18 10 
 
 Crib, single. 
 
 Medium. 
 
 Clay outside. 
 
 
 20 II 
 
 Sheet piles. 
 
 Medium. 
 
 
 
 Typical. 20 12 
 
 Sheet piles. 
 
 Medium. 
 
 Clay outside. 
 
 
 20 13 
 
 Sheet piles. 
 
 Medium. 
 
 Clay outside. 
 
 20 14 
 
 Sheet piles. 
 
 Medium, 
 
 Clay. Equal depth. 
 
 20 15 
 
 Box or crib. 
 
 12' X 36' 
 
 None. 
 
 On grillage. '< 20 16 
 
 Staves. 
 
 36' diam. 
 
 None. 
 
 
 On grillage. 20 17 
 
 Sheet piles. 
 
 So' diam. 
 
 None. 
 
 
 Failed. 24 18 
 
 Canvas on plank. 
 
 So' long. 
 
 Rotten manure. 
 
 
 Bulkhead. 30 19 
 
 Crib, double. 28' X 64' 
 
 Clay. 
 
 3'o" 
 
 Canvas used 32 20 
 
 Box and canvas. 
 
 Square. 
 
 Clay outside. 
 
 
 Movable. 33 21 
 
 Polygon crib. [47' diam. 
 
 Clay. 
 
 4' 6 " 
 
 36 22 
 
 Polygon crib. 
 
 44' diam. 
 
 Clay and gravel. 5' o" 
 
 
 38 23 
 
 Crib, single. i 34' diam. 
 
 Concrete inside. 
 
 
 39 24 
 
 Sheet piles. 13' X 44' 
 
 Clay and gravel. 2' 3" 
 
 
 59 1 25 
 
 Sheet piles. 
 
 Large. 
 
 None. 
 
 Two trials. 
 
 60 j 26 
 
 Sheet piles. 
 
 12' wide. 
 
 Clay. 6' to 8' 
 
 
 60 27 
 
 Sheet piles. 
 
 Medium. 
 
 None. 
 
 
 62 
 
 28 
 
 Sheet piles. 
 
 Medium. 
 
 Gravel. 
 
 Two trials. 
 
 62 
 
 29 
 
 Sheet piles. 
 
 Medium. 
 
 Gravelly clay. 
 
 
 63 
 
 
 Sheet piles. 
 
 18' 6" X 119' 
 
 Concrete inside. 
 
 
 63 
 
 3i 
 
 Sheet piles. 
 
 44' diam. 
 
 Sand and concrete. 7' -f- 
 
 
 64 
 
 32 
 
 Sheet piles. 
 
 Large. 
 
 Clay. ()' o" 
 
 
 66 
 
 33 
 
 Sheet piles. 
 
 15' x 50' 
 
 None. 
 
 
 67 
 
 34 
 
 Sheet piles. 
 
 829' long. 
 
 Clay. 
 
 S' 
 
 
 67 
 
 35 
 
 Sheet piles. 
 
 1 6' X 38' 
 
 Earth outside. 
 
 
 
 /o 
 
 36 
 
 Sheet piles. 
 
 23' X 55' 
 
 Clay. 
 
 2' to 4' 
 
 Removal. 
 
 72 
 
 37 
 
 Sheet piles. 
 
 28' X 28' 
 
 Clay. 
 
 12' -4- 
 
 Removal. 
 
 74 
 
 38 
 
 Sheet piles. 
 
 16' X 42' 
 
 Clay and gravel. 
 
 8' 4- 
 
 Movable. 
 
 74 
 
 39 
 
 Sheet piles. 
 
 Medium. 
 
 Clay outside. 
 
 
 
 77 
 
 40 
 
 Sheet piles. 
 
 Medium. 
 
 None. 
 
 
 
 77 
 
 4 1 
 
 Sheet piles. 
 
 500' long. 
 
 Clay. 
 
 2-7' 
 
 
 77 
 
 42 
 
 Sheet piles. 
 
 18' X 55' 
 
 Clay outside. 
 
 
 
 78 
 
 43 
 
 Metal. 
 
 60' diam. 
 
 Concrete seal. 
 
 
 86 
 
 44 
 
LIST OF ILLUSTRATIONS. 
 
 NUMBER PAGE 
 
 The Pont du Gard, Mimes, France Frontispiece. 
 
 1. Bridge at Shuster, Persia, over the River Karun 2 
 
 2. Bridge over the Adda at Trezzo Milanese 3 
 
 3. Caesar's Bridge over the Rhine 4 
 
 4. A Primitive Solution. (Earth-bank Coffet -dam .) 6 
 
 5. Coffer-dam in Tide- water. (Sheet Piles and Puddle.} 8 
 
 6. Buda-Pesth Suspension Bridge. (Puddle Coffer-dam.} 9 
 
 7. Buda-Pesth Suspension Bridge, Plan of Coffer-dam No. 3 n 
 
 8. Scraper Dredge. (For Drag Dredging, C. & M. V. Ry.) 14 
 
 9. Coffer-dam at Dam No. IT, Gt. Kanawah River. (Earth and Crib.} 15 
 
 TO. Crib Coffer-dam, C., B. & Q. R. R. ( With Puddle Chamber.} 16 
 
 11. St. Lawrence River Bridge, C. P. Ry. (Crib and Coffer-dam] 17 
 
 12. Arnprior Bridge, C. P. Ry. (Crib and Coffer-dam} 18, 19 
 
 13. Crib Coffer-dam, A., T. & S. F. Ry. (A'o Puddle Chamber.} 21 
 
 14. Coffer-dam on Grillage, Payette and Weiser Rivers, U. P 22, 23 
 
 15. Coffer-dam on Grillage, Fort Madison Bridge, A., T. & S. F. Ry 24 
 
 16. A Crib Coffer-dam after a Flood. (Showing Plant.} 25 
 
 17. Apparatus used to force Clay into Crevice of Rock. (Leak.} 29 
 
 18. Details of Canvas and Plank Btilkhead, Keokuk, la 31 
 
 19. Inside View of Bulkhead, Lock pumped Dry, Keokuk, la 34 
 
 20. Canvas Funnel for closing Leaks. (Springs.) 35 
 
 21. Cribs for anchoring St. Louis Coffer-dam. (Crib and Puddle.} 36 
 
 22. Polygonal (Crib} Coffer-dam. Harlem Ship Canal Bridge 38 
 
 23 Details Coffer-dam, Arthur Kill Bridge. (Crib and Puddle.) 37 
 
 24. Coffer dam for Pivot Pier, Coteau Bridge. (Crib.} 38 
 
 25. Perronet's Pile Driver. (Historical; Man Power.) 41 
 
 26. Perronet's Bull-wheel Pile Driver. (Historical; Horse .Power.) 41 
 
 27. Sheet-pile Driver. (Hand-power Derrick.) 41 
 
 28. Pile-driver Derrick for Use on a Scow 42 
 
 29. Lidgerwood Pile-driving Derrick 43 
 
 30. Hammer with Nippers. (For Horse Power.) 43 
 
 31. Pile-driving Scow, New York State Canals. (Steam.) 44 
 
 32. Warrington-Nasmyth Steam Pile Hammer 45 
 
 33. Warrington-Nasmyth Hammer, Fair Haven Bridge 46 
 
 34. Cram-Nasmyth Steam Pile Hammer 47 
 
 35. Machine for sawing off Piles under Water 48 
 
 36. Pile-pulling Lever. (Hand Power.) ' 49 
 
 37. Pile-pulling Scow. New York State Canals. (Steam.) 50 
 
 xiii 
 
XIV LIST OF ILLUSTRATIONS. 
 
 38. Sheet Piles and Sheet-pile Details 51 
 
 39. Charlestown Bridge. Driving Wakefield Sluet Piling 52 
 
 40. Arrangement and Diagrams of Sizes for Sheet-pile Coffer-dam x 55 
 
 41. Sheet-pile Guides and Clamps 57 
 
 42. Coffer-dam for Ann Arbor Bridge, M. C. Ry. (Sheet Piles and Puddle.) 58 
 
 43. Sewer Coffer-dam, Boston Sewerage System. (Sheet Piles and Puddle.} 59 
 
 44. Wakefield Sheet Piling. (Details. ) Ci 
 
 45. Type of Momence and Harper's Ferry Coffer-dams. (Sheet Piling.) 62 
 
 46. Coffer-dam on Charlestown Bridge. (Sheet Piling.} 03 
 
 47. Resevoir Coffer-dam, Fort Monroe, Va. (Sheet Piling.) 65 
 
 48. Compound Sheet Pile 67 
 
 49. Chattanooga Bridge, Bed-rock Pier No. 3 68 
 
 50. Framework of Coffer-dam, Cumberland, Md. (Sheet Piling} 69 
 
 51. Sandy Lake Coffer-dam. (Sh^'t Piling.} 7 o 
 
 52. Coffer-dam and Concrete Pier, Little Rock, Ark. (Sheet Piling 71 
 
 53. Removal of Masonry Pier at Stettin, Germany. (Sheet Piling.} 73 
 
 54. Coosa River Coffer-dam. (Sheet Piling.} 75 
 
 55. Stock Rammer. (For packing Clay to stop Leaks.) 77 
 
 56. Topeka Bridge Coffer-dam. (Sheet Piling.} 78 
 
 57. Havvkesbury Bridge, Caisson No. 6. (Metal Shell.') Si 
 
 58. Group of Cylinders for Pivot Pier. (Metal Shells.} 82 
 
 59. Pier of Two Cylinders, Victoria Bridge. (Metal Shells.} 83 
 
 60. Circular Saw for cutting off piles under Water 84 
 
 61. Cylinder-pier Bridge, Riga-Orel R. R., Russia. (Metal Shells.) 85 
 
 62. Cylinder Piers, with Diaphragm. (Metal Shells.} 86 
 
 63. Circular Granite Pier, Forth Bridge 87 
 
 64. Forth Bridge. (Metal Coffer-dam } 88 
 
 65. Forth Bridge. (Circular Granite Pier and Metal Coffer-dam} 90 
 
 66. Old Bascule Pump. (Hand Power.) 93 
 
 67. Old Chapelet, Side Eelevation. (Water-power Pump.) 94 
 
 68. Old Chapelet, End Elevation. (Water-power Pump.) 94 
 
 69. Hand Pump, Soldered Joints 95 
 
 70. Hand Pump, Screw Joints 95 
 
 71. Diaphragm Pump. (Hand Power.) 95 
 
 72. Van Duzen Jet Pump. (Steam Power.) 96 
 
 73. Lansdell's Siphon Pump. (Steam Power.) 96 
 
 74. Pulsometer Steam Pump 97 
 
 75. Section of Pulsometer 97 
 
 76. Centrifugal Pump, directly connected to Engine 98 
 
 77. Suction Details for Pumps ; 99 
 
 78. Centrifugal Pump, Double Suction 100 
 
 79. Dredging Pump 100 
 
 80. Dredging-pump Piston 101 
 
 81. Lancaster Grapple. (Derrick Dredge.) 102 
 
 82. Sand Digger. (Light Elevator Dredge. ) 103 
 
 83. Osgood Dipper Dredge, New York State Canals IO ^ 
 
 84. Osgood Dipper Dredge, Details, New York State Canals Io ^ 
 
 85. Metal Tube for Concreting Io -. 
 
 86. Metal Bucket for Concreting TO S 
 
LIST OF ILLUSTRATIONS. XV 
 
 87. Concrete Piers. Red River Bridge 109 
 
 88. Concrete Forms, Red River Bridge no 
 
 89. Concrete Forms, Illinois and Michigan Canal in 
 
 90. Stone Crusher and Concrete Mixer, I. and M. Canal 112 
 
 91. Double-drum Guy Derrick, Am. Hoist & Derrick Co 113 
 
 92. Single-drum Horse Power, Con. Plant Mfg. Co .' 114 
 
 93. Double-drum Hoist Engine, Lidgerwood Mfg. Co 114 
 
 94. Crocker-Wheeler Electric Hoist 115 
 
 95. Lidgerwood Cableway Carriage and Skip 1 16 
 
 96. Lidgerwood Cableway at Coosa Dam. (Span 1012 Feet) n3 
 
 97. Hand Drill and Swab 121 
 
 98. Steam-power Well Driller 122 
 
 99. Test-boring Apparatus, Mississippi River Commission 123 
 
 100. Clamp and Maul. (Test Boring.) 124 
 
 101. Pier of Omaha Bridge, Union Pacific System 126 
 
 102. Russian Pier, Russian State Railways 127 
 
 103. Cresy's Experiments on the Form of Piers. 128 
 
 104. Cresy's Experiments on the Form of Piers 130 
 
ARTICLE I. NTT = 
 
 THE COFFER-DAM PROCESS FORMERS. 
 
 ~~ HISTORICAL DEVELOPMENT. 
 
 HE continued increase in the weight of our bridge super- 
 structures and of the loads they have to carry has led to 
 increased care, to a very gratifying degree, in the prep- 
 aration of the foundations for bridge piers and abutments. 
 An old authority very truly states "The most refined elegance of taste 
 as applied in the architectural embellishment of the structure; the most 
 scientific arrangement of the spans and disposition generally of the superior 
 parts of the work; and the most judicious and workmanlike selection and 
 subsequent combination of the whole materials composing the edifice, are 
 evidently secondary to the grand object of producing certain firm and solid 
 bases whereon to carry up to any required height the various pedestals of 
 support for the spans of the bridge." 
 
 There is every reason to believe, from the bridges of the Romans still 
 extant and of those of ancient and mediaeval times of which there are remains 
 or records, that the foundations were carefully considered. 
 
 The most ancient form was likely begun by dumping in loose stones until 
 the surface of the water was reached and the masonry could then be com- 
 menced without the necessity for any method of excluding the water. The 
 oldest civilizations were in tropical or semi-tropical countries where the 
 streams are dry beds for many months in the year and suitable foundations 
 were easily made without water to contend with. Where the bottom of the 
 stream was rock, the engineering could be very little improved upon to-day, 
 and even where there was shallow water on rock bottom, the piers were well 
 founded in the shallowest places, the bridge often winding across the stream 
 in serpentine form, similar to the bridge over the river Karun, at Shuster, 
 Persia. Fig. 1. 
 
 The arch was developed to such an extent by the Romans, and the spans 
 were increased to a length which rendered the construction of piers in the 
 water unnecessary for short bridges, the abutments or skewbacks being 
 without the stream on either bank. 
 
 The difficulty of founding piers in midstream was doubtless the con- 
 trolling cause for the larger spans, such as the one built at Trezzo, over the 
 river Adda, by order of the Duke of Milan, sometime prior to the year 1390. 
 The span at low water was 251 feet, the single arch being of granite in two 
 
THE COFFER-DAM PROCESS FOR PIERS. 3 
 
 courses. The placing of a middle support was doubtless found to be imprac- 
 ticable and caused the design of an arch which has never been equaled or 
 eclipsed. Fig. 2. 
 
 The construction of roads has ever been the harbinger of civilization, 
 and with the spread of civilization came a demand for the improvement of 
 means of communication. The engineer was called upon to construct better 
 and greater bridges in a permanent manner, which led to the origin and 
 development of the four methods for founding in water that were used in 
 
 FIG. 2. BRIDGE OVER THE ADDA, AT TREZZO, MILANESE, A PROBABLE RESTORATION. 
 THIi SHADED PORTION OF ARCH RINGS IS A I, I, THAT REMAINS. 
 
 olden times. These may be classified as, first, the method with open cais- 
 sons; second, the use of piles with a capping of coarse concrete about the 
 tops; third, the use of piles after the manner of the French encaissement; 
 and fourth, the use of coffer-dams. A fifth method might be added, in 
 which the bridge was built on dry land adjacent to the stream, and the river 
 diverted to a new channel afterwards excavated under the completed struc- 
 ture. This is, however, an avoidance rather than a solution, unless the river 
 is to be diverted in the course of its improvement. 
 
 The first method, as described in old treatises or accounts, consisted of 
 little more than baskets formed of branches of trees, weighted with stone to 
 sink them, and after sinking filled with loose stone to near low water level, 
 
4 THE COFFER-DAM PROCESS FOR PIERS. 
 
 where the masonry could be commenced. These baskets were similar in 
 construction to the mattresses used in the bank revetment of the Mississippi 
 or the bamboo casings used by the Japanese to hold stones in place on bank 
 protection. 
 
 An improvement was effected by using in place of baskets, boxes or small 
 open caissons which were sunk and filled in the same manner, several being 
 used for one pier. This was the method used at Black friars bridge and 
 also at Westminister bridge, over the Thames, and has been much used in 
 recent times, the caisson being built large and strong enough for the entire 
 pier, which is built up as the caisson sinks. 
 
 The second method consisted of driving piles over the area of the foun- 
 dation until the heads were below low water level, and spaced at distances 
 
 
 FIG. 3. TEN DAYS TO CONSTRUCT; LENGTH ABOUT A QUARTER MII.E; DEPTH WATER 
 
 16'; WIDTH, 25'; BEAM, 2 X THICK; ABOUT 50 PIERS. 
 
 apart as required by the nature of the bottom, similar to the methods in 
 vogue to-day. The heads of the piles were not driven to the same level, 
 however, and were incased in a form of coarse concrete such as was used by 
 the Romans, but what is now called beton. This was leveled up and on it 
 was laid the stone for the footing course of the pier. 
 
 The third method of encaissement was probably an improvement of the 
 dumping in of loose stone on which to place the pier, and consisted in inclos- 
 ing the space for the pier with sheet piling, after which the loose material 
 was removed from the bottom as much as possible and the stone dumped 
 inside until nearly up to low water, at which time the pier could be begun. 
 
THE COFFER-DAM PROCESS FOR PIERS. 5 
 
 These last two methods doubtless met with much favor owing to the 
 familiarity with pile driving, in which the Romans especially were proficient. 
 Caesar's bridge over the Rhine was built entirely on piles, and in a view of it 
 after the old print in the Museum de St. Germaine, is pictured a pile driver 
 on a float in position for driving. Fig. 3. 
 
 This third method was the early type of the crib which has been such a 
 factor in the building of the earlier foundations over our American rivers. 
 Crossed timbers laid up crib fashion with rectangular openings or cells 
 between the timbers were sunk and filled with broken stone on which to 
 build the pier. 
 
 These methods were all deficient in affording no means of seeing or mak- 
 ing a careful examination of the bottom on which the foundation was to be 
 placed, and with the advent of more permanent structures of greater magni- 
 tude the coffer-dam came into use. This allowed the bottom to be freed 
 from water and after a careful examination and preparation of the founda- 
 tion, the work could proceed in the dry until above water level. 
 
 The pneumatic caisson is now in general use for all foundations that 
 must go to any considerable depth below the water and has even been used 
 in some instances where the depth was slight, but where for various reasons 
 it was deemed expedient louse compressed air caissons. Recent expressions 
 from some engineers of high standing would indicate that they do not con- 
 sider it good practice to use coffer-dams in any case, one making the state- 
 ment that he had not used a coffer-dam for thirty years, while another 
 seemed to think it a matter to be left to the pleasure of the contractor. That 
 the use of this method has gotten into disfavor seems to be beyond question 
 and it will be the purpose of the succeeding pages to learn to some extent 
 why this is so, but mainly to show from successful examples how to pro- 
 ceed, that success instead of failure may result. Any attempt to account for 
 the origin of the coffer- dam process would be futile, inasmuch as the savage, 
 wishing to free a space from water, doubtless banked up earth about the 
 area and. scooping out the water with his hands, laid the ground bare for 
 inspection. From so simple a beginning, the first method likely to occur to 
 a mind capable of reasoning, can readily be imagined the course of develop- 
 ment of coffer-dams. 
 
 The most simple form in use at the present time, where the water is 
 quiet, is shown in the Fig. 4, and consists principally of a bank of earth 
 which is made thick enough to be nearly or quite impervious to water, the 
 earth being prevented from caving into the excavation by piles supporting 
 a timber casing. Some of the recorded examples of the early use of this 
 process are of interest in illustrating the care which was bestowed upon 
 their construction in important works and will call attention to that incess- 
 ant care which is necessary to success in any work of this character. 
 
6 THE COFFER-DAM PROCESS FOR PIERS. 
 
 Robert Stevenson, the great English engineer, thought it not beneath 
 his dignity to give full instructions as to the construction of the coffer-dams 
 for the Hutcheson bridge over the Clyde at Glasgow. The bridge consisted 
 of five arch spans, the total length between the abutments being 404 feet 
 and the width 38 feet. The four piers were from 11 to 12 feet in thickness, 
 being designed to take up the arch thrust, and 48 feet in length at the foot- 
 
 FIG. 4. A PRIMITIVE SOLUTION. 
 
 ing. The specifications written at Edinburgh in April, 1828, are so explicit 
 that they will be quoted in full on this point: "It having been ascertained 
 by boring and mining that the subsoils of the bed of the river consist of 
 gravel, sand and mud to the depth of 27 feet and upwards, it becomes 
 necessary to prepare foundations of pile work for the bridge; and, therefore, 
 
THE COFFER-DAM PROCESS FOR PIERS. 7 
 
 to insure the proper and safe execution of the works, coffer-dams are to be 
 constructed around each of the foundation pits of the two abutments and 
 four piers of such dimensions as to afford ample space for driving piles, fix- 
 ing wale pieces, laying platforms, pumping water, and setting the masonry; 
 and likewise for the construction of an inner or double coffer-dam should 
 this ultimately be found necessary. The framework of the coffer-dams is to 
 consist of not less than two rows of standard or gauge and sheeting piles, 
 kept at not less than three feet apart for the thickness of a puddle wall or 
 dyke, which space is to be dredged to a depth of not less than nine feet under 
 the level of the summer watermark above described, before the sheeting 
 piles are driven. The gauge or standard piles are to measure not less than 
 24 feet in length and 10 inches square. They are to be placed three yards 
 apart and driven perpendicularly into the bed of the river to the depth of 
 sixteen feet under the level of the summer watermark, thereby leaving 
 eight feet of their length above that mark. Runners or walepieces of tim- 
 ber nine inches square are then to be fitted on both sides of each row of 
 gauge piles, to which they are to be fixed with two screw bolts of not less 
 than one inch in diameter, passing through each of the gauge piles. One 
 set of these inside and outside walepieces is to be placed at or below the level 
 of summer watermark, and the other set within one foot of the top of each 
 row of said piles, the whole to be fixed with screw bolts in the manner above 
 described. The walepieces are to be four and one-half inches apart in order 
 to receive and guide the sheeting piles. This is to be effected by notching 
 the walepieces into the gauge piles. The sheeting piles are to be 21 feet in 
 length, 4^ inches in thickness, and not exceeding 9 inches in breadth. 
 They are to be closely driven, edge to edge, along the space left between 
 the walings, and each compartment of the sheeting between the gauge piles 
 is to be tightened with a key pile. The coffer-dam frames are to be properly 
 connected with stretchers and 'braces before commencing the interior exca- 
 vation. Each coffer-dam is to be provided with a draw-sluice, fourteen 
 inches square in the void, with a corresponding conduit passing through the 
 puddle dyke at the level of summer watermark. To render the coffer-dams 
 water tight the whole excavated space between the two rows of piling is to 
 be carefully cleared of gravel, sand or other matters, to the specified depth, 
 and clay well punned or puddled is then to be filled in and carried up to the 
 level of the top of the sheeting piles. But if it shall, notwithstanding, be 
 found that the single tiers of coffer-dam do not keep the foundation pits suf- 
 ficiently free of water for building operations, the water must either be 
 pumped out and kept perfectly under by steam or other power, or else 
 excluded by the construction of a second tier of coffer-dam similar in con- 
 struction to the first. For the foundation pits of the two abutment piers on 
 either side of the river it is not expected that more will be required on the 
 
8 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 landward side for keeping up the stuff than a single row of gauge and sheet- 
 ing piles; but if the engineer shall find other works necessary upon opening 
 the ground they must be executed by the contractor and shall be paid for 
 agreeably to the contract schedule of prices for the regulation of extra and 
 short works. The stuff within the coffer-dams is to be excavated to the 
 depth of ten feet under the level of summer watermark for each of the piers 
 and eight feet for each of the abutments." 
 
 The present practice of leaving all this to a contractor, whose idea is too 
 often to sacrifice everything to cheapness, appears in very unfavorable con- 
 trast to this careful description. 
 
 An article on founding by means of coffer-dams, published in 1843, 
 gives directions for placing a coffer-dam in forty feet of tide water; and 
 
 FIG. 5. COFFER-DAM IN TIDEWATER. 
 
 although the engineer of to-day would use some other method for such a 
 depth, an illustration, Fig. 5, and short description of it are given, as ideas 
 may be gained for application to ordinary works. 
 
 The water was assumed at ten feet deep for low tide, twenty-eight feet 
 at high tide, with twelve feet of sand and gravel to be removed to expose the 
 clay on which the pier was to rest. Four rows of piles were to be driven 
 around the area, the outer row to within one foot of low water, the two rows 
 in the middle to within three feet of high water, the inner row to eleven feet 
 above low water, and all to be down five feet into the clay. The outer row 
 of piles to be six by twelve inches, the two rows in the middle twelve by 
 twelve inches, and the inner row eight by twelve inches; all driven close 
 together and to have walingpieces, braces and brace rods as shown in cross 
 section. The rows to be six feet apart and to be filled in between with a 
 puddle of clay mixed with sand and gravel. 
 
 The report of W. Tierney Clark, the engineer of the Buda Pesth suspen- 
 sion bridge, gives an account of what are probably the largest bridge coffer- 
 
THE COFFER-DAM PROCESS FOR PIERS. 9 
 
 dams ever constructed. Some other method would now be used for such a 
 location, but this fact will not detract from the lessons that may be drawn 
 from them. 
 
 The Danube was crossed at Buda Pesth previous to the year 1837 by 
 means of a bridge of boats which had to be taken up during the winter and 
 the passage made by ferry or on the ice, so that for six months of each year 
 there was great risk in crossing and frequent loss of life. The building of a 
 permanent bridge was brought about through the efforts of the Count 
 Szechenyi, who, as a member of a committee, proceeded to England in 1832 
 and after a careful investigation of existing works decided upon the con- 
 struction of a suspension bridge. The greatest question for solution was 
 the founding of the two towers in a river like the Danube, where the ice 
 
 Trans\crtt Sfctic 
 
 J Ccfler Dam' 
 
 FIG. 6. BUDA PESTH SUSPENSION BRIDGE. 
 
 throughout the long winter wrought havoc with everything in reach. The 
 ice in the river in February, 1838, was from six to ten feet thick near the 
 site of the proposed piers. On March 9 a movement occurred across the 
 whole river and for a length of 350 yards, the whole moving in a solid 
 mass. On March 13 it moved again 400 yards and three hours later a gen- 
 eral breaking began. The ice piled up on the shoals causing a sudden rise 
 to twenty-nine feet five inches above zero, and while it was at this height 
 for only a few hours, it is recorded that a great part of Buda and two-thirds 
 of Pesth were destroyed and many lives lost. 
 
 The extraordinary design of the coffer-dams can the more readily be 
 understood after this description, it being doubted by many persons at that 
 time whether piers could be placed in the river by any means. Fig. 6. 
 
10 THE COFFER-DAM PROCESS FOR PIERS. 
 
 The drawings reproduced are of coffer-dam No. 3 which was about 72 
 feet in width and about 136 feet in length inside the puddle walls, there 
 being two puddle chambers, each five feet in width. From a point about 
 thirteen feet above the clay on which the tower was to rest, was an inside 
 wall of sheet piling, this space being nearly filled after excavating, with a bed 
 of concrete. The piling of each row, from forty to eighty feet in length, 
 was all carefully sized to fifteen inches square, shod with iron and driven 
 close together, penetrating twenty feet below the bed of the stream or forty 
 feet below the zero level. The framing of the ice breaker and the bracing 
 within the dam was of enormous strength. The number of piles driven in the 
 four coffer-dams reached the enormous total of 5,224, and of the 1,227 driven 
 in darn No. 3, 16^ P er cent, were drawn and redriven. These piles and the 
 timber were obtained from the forests of Bavaria and Upper Austria. Fig. 7. 
 
 The first pile on dam No. 3 was set on April 8, 1842, but owing to the 
 difficulties encountered it was not finished until three years later April 4, 
 1845. From six to seven days were occupied at the first in driving a pile 
 to a depth of five or six feet into the clay, but as the work progressed the 
 difficulty increased, the operation of driving one pile consuming from twelve 
 to fourteen days, many piles breaking short 'off so they could not be with- 
 drawn, and the gravel was dredged out from behind and a second row driven. 
 The report further describes the difficulty of the work: "The dredging for 
 the No. 3 dam was carried on to the average depth of forty-four feet from 
 the top of the outer row of piles, leaving about ten feet of gravel to drive 
 through, and extra piles were driven where the gravel found its way between 
 the piles, as well as where it was known the piles were not driven to the 
 proper depth, or were broken or otherwise injured. As the gravel was 
 dredged out to the above depth, the inner and middle row of piles were 
 driven, and a great part of them got down as was supposed to the requisite 
 depth. The work was carried on in the above manner until the 7th of No- 
 vember, when from the appearance of several piles which were pulled up, 
 and from other causes, it became apparent that the outer row was in a much 
 worse state than had been expected and was almost a matter of certainty, 
 that those piles which had taken ten or twelve days to get down were not 
 driven to the proper depth by at least three or four feet, having upset or lost 
 their points to that extent. There was likewise every reason to believe that 
 many of them were broken or dangerously crippled. Added to this the 
 Danube was rising, and at the late time of the year, with winter rapidly 
 approaching, the general appearance of the dam was anything but satisfac- 
 tory. Upon mature consideration the only course appeared to be to drive a 
 much greater number of piles than was at first calculated upon, and another 
 complete row of piles was driven all round at intervals of fifteen inches apart, 
 and in some cases double and triple piles were driven during the progress of 
 
12 THE COFFER- DAM PROCESS FOR PIERS. 
 
 the dredging. At the commencement of the driving a few were got down 
 to the depth of fifty-seven or fifty-eight feet, being from three to four feet in 
 the clay; but as the gravel began to get compressed many of them would 
 not penetrate more than fifty- four or fifty-five feet, the sharp angular gravel 
 overlying the clay appearing to be compressed into a substance as hard as 
 rock." 
 
 The puddle used was clay mixed with about one-third clean gravel, it 
 having been found to set quite solid, from experiments made by sinking 
 specimens in the Danube. When leaks occurred they were closed by driv- 
 ing square timbers down thirty or forty feet into the puddle to pack it or 
 by driving new piles to close the cracks and in some cases by driving sheet 
 piling. 
 
 Experiences of this nature led to the disuse of coffer-dams for founda- 
 tions to such depths, but a very small percentage of the care exercised and 
 the persistence shown in this work would lead to greater success on ordi- 
 nary foundations. 
 
 The class of work to which coffer-dams may still be applied will be shown 
 in the succeeding pages and the examples from actual practice will show in 
 some measure the care that must be exercised in the first construction to 
 prevent failure, and the expedients adopted to overcome unavoidable acci- 
 dents. 
 
 "In every man's mind, some images, words and facts remain, without 
 effort on his part to imprint them, which others forget, and afterwards these 
 illustrate to him important laws." 
 
ARTICLE II. 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 CONSTRUCTION AND PRACTICE. 
 
 HE exact definition of the term coffer-dam "a water-tight 
 inclosure, from which the water is pumped to expose the 
 bottom and permit the laying of foundations" is the 
 class of structure which is to be considered, although in 
 the construction of them cribs or caissons may be employed and utilized; the 
 essential purpose being to form an inclosure as nearly watertight as possible 
 in order that the expenditure of power for pumping out the water may be of 
 small amount. 
 
 The attainment of this when the water is shallow and has little current 
 we have seen to be easily accomplished by means of a bank of clay or clayey 
 gravel. 
 
 This form may also be employed in still water up to about four feet in 
 depth by the addition of sheet piling or a casing supported by ordinary piles 
 to prevent the embankment from caving into the excavation. Where the 
 bottom is of soft mud or porous material over a solid clay or gravel, as much 
 as possible of the porous material should be removed before forming the 
 embankment, thus preventing leakage underneath. In very shallow water 
 this can be accomplished by shoveling and with large hoes or scoops, but 
 with several feet of water to contend with, some form of dredge or scraper 
 must be employed. A very convenient form of scraper used by M. L. Byers 
 on the Cinti. & Mus. Valley Railway is described in Vol. 31 of the 
 ''Transactions of the American Society of Civil Engineers," and consists of old 
 boiler iron, strengthened by three ribs of light iron rail as shown in Fig. 8. 
 This was operated by a double drum 20 horse-power Mundy hoisting engine, 
 with the towing line running directly from one drum to the scraper and the 
 back line from the other drum over a sheave to the front of the scraper. The 
 excavating averaged about forty-five yards of material each day during 
 twelve days' work. The weight of the device was about one thousand 
 pounds. 
 
 Where the material is very soft, a hand dredge called a spoon will accom- 
 plish the work at about the same cost as excavating on dry land. The 
 spoon usually consists of a long pole, having a cutting ring fastened at one 
 end, and to this ring is attached a canvas bag to contain the excavated ma- 
 
 13 
 
THE COFFER-DAM PROCESS FOR PIERS 
 
 terial. The ring is hung from a derrick with a set of falls, being guided with 
 the pole, as it is dragged forward by the derrick through the material to 
 be excavated. 
 
 Excavating may be done on all the larger rivers by employing the sand 
 or gravel diggers which are most always to be found, the dredging being 
 accomplished by means of a series of buckets on a belt or on chains operated 
 through a well in the bottom of a barge. Dredging by machinery on a large 
 scale will be considered later on in some detail. 
 
 The method of embankment is sometimes employed for greater depths 
 than four feet and in some instances successfully. 
 
 The Chanoine dams on the Great Kanawah River required substantial 
 foundations beneath the water, and to accomplish this Addison M. Scott, the 
 
 resident engineer, 
 employed log cribs 
 about the spaces, with 
 earth banked up on 
 the outside. This 
 work is described in 
 the report of the Chief 
 of Engineers for 1896. 
 The site of the 
 navigation pass of 
 dam No. 11 including 
 the center pier, re- 
 quired a coffer-dam 90 
 feet wide and 330 feet 
 long inside. (Fig. 9.) 
 This area including 
 the necessary room for 
 the cribs, was dredged 
 out to hardpan from 
 20 to 24 feet below low 
 water. The log cribs 
 which contained about 
 84,000 lineal feet of 
 
 logs, were sunk in sections 19 feet wide and 20 feet long. They were 
 sheathed up to about three feet above low water, with sheet piling in 
 three layers, on the Wakefield system. The driving was accomplished by 
 attaching an eighty-pound weight to an Ingersoll-Sergeant drill run by steam 
 and utilizing the reciprocating motion by attaching the drill with clamps 
 to the tops of the sheathing, following it down as it was driven, after the 
 manner of the Nasmyth steam pile hammer. This device, which is one of 
 
 FIG. 8. SCRAPER DREDGE. 
 
THE COFFER-DAM PROCESS FOR PIERS. 15 
 
 the most ingenious ever devised for the purpose, was arranged by the con- 
 tractor's engineer, S. H. Reynolds, and was a complete success. 
 
 The tops ol the cribs were ten feet above low water, and the bottoms 
 rested on the hardpan, making a total height of from thirty to thirty-four 
 feet. 
 
 The cribs were tilled with sand and gravel that had been dredged out, 
 
 FIG. 9, COFFER-DAM AT DAM NO. 1 
 
 GREAT KANAVVAH RIVER. 
 
 but the outside was banked up with selected clay and dredged material, 
 which was protected by a layer of riprap up to about low water. 
 
 When the coffer dam was first pumped out several leaks were developed, 
 but after one week in perfecting the details the pumps were started regu- 
 larly and no serious trouble was had afterward. This is only one of a ser- 
 ies of coffer-dams which have been constructed on the several dams in this 
 river, and owing to the care exercised good results were obtained uniformly. 
 
 The construction of a similar piece of work on the Ohio river was begun 
 by Major R. L. Hoxie, corps of engineers, and is described in the report of 
 1895: "It was originally planned to enclose the site of the dam and lock 
 within a coffer-dam, and work was commenced upon that basis. But on 
 
10 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 attempting to pump out the inclosure, it was found that water came in in 
 large quantities, not only under the dam but from springs in the bottom, 
 and all attempts to close these by dumping clay and gravel was a failure. 
 The area inclosed by the dam was about 600 by 200 feet or about three acres 
 of river bottom. The deposit of sand and gravel overlying the rock was 
 about thirty-five feet thick, the rock being forty-five feet below the water 
 level, while the plans required an excavation twenty feet deep below this 
 water surface. The bottom deposit had been worked over for years by sand- 
 diggers who threw back the large stones and coarse gravel after removing 
 
 FIG. 10. CRIB COFFER-DAM; CHICAGO, BURLINGTON AND QUINCY RAILROAD. 
 
 the fine sand, this work resulting in a very permeable bottom, with possible 
 channels of comparatively large dimensions extending to unknown distances 
 beyond the limits of the coffer-dam." 
 
 This is perhaps the most frequent source of failure of a well constructed 
 coffer-dam and should always be guarded against by removing as much of 
 the porous material as possible, by dredging before the construction of the 
 coffer-dam is begun. 
 
 Cribs are very easy to construct, usually very substantial, and easy to 
 
THE COFFER-DAM PROCESS FOR PIERS. 1 7 
 
 make use of by floating to position and then sinking in place. A very sim- 
 ple form that has been used on the Chicago, Burlington & Quincy railroad 
 is described by E. J. Blake, chief engineer. Where the water is shallow 
 they have been built in the form shown (Fig. 10) of fence boards spiked 
 one piece on another; with deeper water they are made of heavier timber 
 2"x8" or 2"xlO". They are built on the water and are tied across at inter- 
 vals by pieces spiked through the wall, w T hich pieces should be carefully 
 fitted to prevent leakage. In some cases where the bottom is soft, instead 
 Of dredging, a bottom is added to the crib to prevent the filling from squeez- 
 ing its way out from under the edge. 
 
 When the crib has reached bottom, being sunk by weighting it down if 
 
 n 
 
 FIG. 11. ST. LAWRENCE RIVER BRIDGE CRIB AND COFFER-DAM, CANADIAN 
 
 PACIFIC RAILWAY. 
 
 necessary, the chambers are filled with clay puddle and clay is banked up 
 around the outside to prevent water running under. The crib" is made large 
 enough so that the excavation will leave an easy slope to the inner edge of 
 the timber work. This form can be made to conform readily to the contour 
 of the bottom by starting the layers of timber at different elevations. No 
 leakage has been experienced except what, can readily be kept under control 
 with ordinary sized centrifugal pumps. The cost of construction is gener- 
 ally a minimum, as there are usually plenty of old timbers available for use 
 from the railroad yards. 
 
iS 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 Cribs constructed in a similar manner but with only one wall of timber 
 have been used successfully on the Canadian Pacific Railway by P. Alex. 
 Peterson, chief engineer. 
 
 The bracing is very efficiently attached by dovetailing it into the sides, 
 while the form of the crib enables it to withstand the force of the current 
 and the ice. The projections on the inside are to prevent the water from 
 forcing its way up between the sides and the concrete filling when the dam 
 is pumped out. These projections answered their purpose very effectually , 
 and when the dam was pumped out it remained dry enough to lay the 
 masonry without any additional pumping. 
 
 Illustrations are given of a crib of this character which was used on the 
 St. Lawrence river (Fig. 11) similar ones being used for the other piers of the 
 same bridge, and of the crib used for the Arnprior bridge. (Fig. 12.) This 
 shows the concrete which was deposited on which to found the masonry, and 
 
 3 
 
 I 
 
 E 
 
 FIG. 12. ARNPRIOR BRIDGE CRIB AND COFFER-DAM, CANADIAN PACIFIC* RAILWAY. 
 
 which formed a watertight bottom so that the crib could be pumped out for 
 the laying of the stone. 
 
 The practice on the Atchison, Topeka & Santa Fe railroad has been 
 in some respects similar to what has been given. C. D. Purdon, assist- 
 ant chief engineer, states that cribs built of old timbers are used when 
 such material as stringers 7"xl6" is plentiful, each course being stepped in 
 about one-half an inch to give a batter. For use in sand when rocks and 
 drift are likely to be encountered a crib is made by constructing a frame of old 
 bridge timbers and sheathing it with plank. (Fig. 13.) This is sunk by digging 
 out the sand, which is shoveled first into box A, then to boxes B, then to 
 C, and then outside. The suction pipe is shown in dotted lines, the pumping 
 being accomplished with a centrifugal pump. This plan works very sue- 
 
20 THE COFFER-DAM PROCESS FOR PIERS. 
 
 cessfully on the streams in Colorado and New Mexico where the water is 
 mostly in the sand and but little shows as surface water. 
 
 The Arkansas river bridge of the St. Louis & San Francisco railroad at 
 Tulsa was built over a bottom of gravel and riprap above rock, which was 
 quite level and about seven feet below low water. Cribs were constructed 
 for coffer-dams similar to the one just described and set on the bed of the 
 stream. Clay from the bank was dumped outside and as the crib was dug 
 out and sunk, the clay followed down and kept out the water. 
 
 When the bottom is of clay or of sand without obstructions, sheet piles, 
 either tongue and groove or the Wakefield, are driven around a crib. 
 
 Geo. H. Pegram, chief engineer of the Union Pacific system, has made the 
 construction of coffer-dams conform to available material and local condi- 
 tions. At the crossing of the Republican river in Kansas, where the bottom was 
 sandy, a single thickness of four-inch V-shaped tongue and groove sheet- 
 piling, with the usual guide piles and wales, served to form a watertight 
 structure. 
 
 Where a gravel bottom overlaid a hard soapstone, as on some work in 
 Idaho, with seven feet of water to contend with, the coffer-dam was made of 
 Wakefield piling, formed of 1^-inch sized plank. The joints were tightened 
 with cement; and sand, gravel and straw placed outside to prevent leaking. 
 Wakefield piling has also been used for clean rock bottom, placed in two 
 rows about the depth of the water apart. Intermediate cribs filled with rock 
 were used to sink them. The ends of the piling were sharpened and driven 
 on the rock until broomed up and rendered nearly watertight, when gravel 
 mixed with straw was placed around outside to close any remaining leaks. 
 
 In cases where ordinary piling has been driven and a grillage laid upon 
 them to receive the masonry, a coffer-dam is constructed as shown (Fig. 14) 
 in which to lay the masonry. The construction of this is fully shown in the 
 different views given. 
 
 Another form of coffer-dam for the same purpose was constructed by 
 Octave "Chanute in laying the masonry of the pivot pier for the Fort Madison 
 bridge over the Mississippi river, on the line of the Atchison, Topeka & Santa 
 Fe railroad. (Fig. 15). This is described in the Engineering News of June 2, 
 1888, by W. W. Curtis, resident engineer : "The grillage (for the pivot pier) 
 is four feet, three inches thick, the upper fifteen inches being dressed to an 
 accurate circle of the desired diameter. The coffer-dam was footed against 
 these two courses and was formed of 3"x8"pine plank staves, dressed on the 
 sides to a slight bevel around which were placed seven wrought iron hoops 
 4"x T y, 5"x ", and 6"xyV'> similar to those used for water tanks, and 
 screwed up tight. Inside of these, circular braces of plank were fitted. As 
 a water pressure of nineteen feet was to be resisted, additional security against 
 leakage was obtained by placing a string of candle wicking vertically between 
 
r 
 
 TTTT 
 
 1 
 
Half Plan. 
 
 FIG. 14. COFFERDAM ON GKILLAGK ; PAYETTE AND WEISER RIVER BRIDGES. 
 UNION PACIFIC SYSTEM. 
 
6' O" 
 
 6'0' 
 
 >4"x6"*7' 
 
 3"xl2"xiz' 
 
 3 * 12" x 12' 
 
 View. 
 
 FIG. 14 COFFER-DAM ON GRILLAGE, PAYETTK AM) WEISER RIVER 
 BRIDGES. UNION PACIFIC SYSTEM. 
 
24 THE COFFER-DAM PROCESS FOR PIERS. 
 
 each stave. When the caisson was submerged to about full depth it became 
 necessary for the steamboat to assist it into final position. A 12"xl2" post 
 was bedded in the concrete in the center of the pier, with four braces run- 
 ning to the circular bracing of the sides. This makes a very cheap coffer- 
 dam and was found to work very well." 
 
 An attempt to use a form similar to this was made in constructing the 
 Walnut Street bridge at Philadelphia. This is described by Geo. S. Web- 
 ster, chief engineer Bureau of Surveys, in the Engineering News of March 
 15, 1894: "In founding the river piers, the Robinson coffer-dam was first 
 tried, but was abandoned after three of them had failed by collapsing. This 
 
 Section o-f Pier 
 
 FIG. 15. COFFER-DAM ON GRII,I,AGB, FORT MADISON BRIDGE, ATCHISON, TOPEKA 
 
 AND SANTA FF, RAILWAY. 
 
 dam may be briefly described as follows : A circular platform about eighty 
 feet in diameter supported upon piles at an elevation of about four feet above 
 high water was first constructed. Square piles of 12"xl2" yellow pine were 
 then prepared by spiking a 3"x4" timber flat, along the middle of one side, 
 and two others along the edges of the opposite side, forming a tongue and 
 groove on each pile. The tops were squared off and the bottom ends 
 pointed to a wedge shape. These piles were then driven close together 
 against the edge of the circular platform and down to rock. Mr. Robinson's 
 idea was that the mud overlying the rock would hold the piles in position at 
 the bottom, and if the top ends were held by an outside hoop, the dam would 
 be secure without internal bracing to resist collapsing pressure. In the first 
 trial the hoop was made of boiler iron some four feet or more in width. In 
 the second dam it was formed of a heavy steel railway rail, and in the third 
 
THE COFFER-DAM PROCESS FOR PIERS, 25 
 
 dam the hoop was the same as in the second, but it also had a number of 
 radial rods in addition. The first dam was pumped out and held for nearly 
 an hour before collapsing, but the others collapsed before being entirely 
 pumped out. After the third failure this form of dam was abandoned." 
 
 It would seem likely from a comparison of the two cases, one being en- 
 tirely successful and the other a failure, that had the Walnut street dam 
 been supplied with additional bands lower down and provided with some 
 means of tightening, with several internal bracing ribs of timber, it would 
 have proven a success. These bands and ribs could likely have been placed 
 by a diver. 
 
 The uncertainty which always exists regarding any construction under 
 
 FIG. 16. A CRIB COFFER-DAM AFTER A FIvOOD. 
 
 water makes it imperative that every precaution should be taken to guard 
 against troubles that might arise, by making the construction of no doubtful 
 form and in no doubtful manner from its first inception. 
 
 The nature of the bottom will always indicate the method of construc- 
 tion which should be adopted in a given case, but it would be rarely that the 
 preliminary dredging could be dispensed with. It is true that there are 
 cases where there is a deposit overlying a seamy rock, and the water will 
 find its way along the seams, bubbling up in springs inside. Resource must 
 be had to cutting off the flow, by puddling on the outside, sometimes ex- 
 tending the operations a distance of a hundred feet or more away, until 
 enough of the flow has been stopped so that the water can be kept down b}' 
 a reasonable amount of pumping. 
 
26 THE COFFER-DAM PROCESS FOR PIERS. 
 
 The next precaution after dredging, is the building of some form of coffer- 
 dam which shall effectually exclude any flow through the sides of the dam. 
 TJiis we have seen to be accomplished in many cases by means of a bank of 
 clay, or a row of sheet-piling, and in some cases by a single walled crib. But 
 in the last two methods a supplementary bank of clay or clayey gravel on 
 the outside is necessary to prevent leakage. 
 
 This bank may be protected from wash by covering it with clay, sand or 
 gravel in gunny sacks, or by ripraping up to about low water, as was done 
 on the Kanawah dams. 
 
 Double walled cribs and coffer-dams constructed with two rows of water- 
 tight sheet piling, require to be puddled with a carefully selected material. 
 While clay can be used with a good degree of success, it will be found better 
 to use a clayey gravel or to mix the clay and gravel, as was done at the 
 Buda-Pesth bridge. When a small leak starts through a pure clay puddle, 
 it washes out the clay in considerable quantities and a dangerous leak is 
 soon developed. With the admixture of gravel, however, a leak is stopped 
 almost as quick as started by the heavier gravel falling into and closing the 
 void. 
 
 It will generally be found advantageous to use a bank of clay outside of 
 a double walled dam, unless it might be a case where sheet piling has been 
 driven to rock, and even then a certain amount of material in sacks should 
 be used to prevent wash or the cutting out of the earth around the sheeting. 
 
 Whatever excavation is taken out of the interior of the coffer-dam after it 
 has been pumped, should be dumped at the upstream end and corners, or to 
 fill any holes or pockets there may be around the sides or ends. 
 
 Cutwaters should be added to all coffer-dams which are built in rivers 
 having a swift current or a heavy flow of ice, as was the case at Buda-Pesth 
 and on the Canadian Pacific examples. They must also be used in rivers 
 where the run of drift with each rise is of large amount. For the purpose of 
 preventing wash around a dam, a cutwater of plank supported by a frame of 
 timber may be constructed separate from the main structure, or a V-shaped 
 row of sheet piling driven up stream. On rock, a timber crib of triangular 
 shape, built of round logs, may be sunk up stream and filled with broken 
 stone. Such a crib can be utilized in anchoring the main crib of a coffer- 
 dam, as was done at St. Louis, and which will be described in future pages. 
 
 More fitting language cannot be found for closing words than those used 
 in Wellington's monumental work on railway location: ''The uncertainty 
 as to the exact requirements to be fulfilled by the works when completed is 
 a disadvantage, indeed, which cannot be escaped; but the more difficult it is 
 to reach absolute correctness, the greater need we have of some guide which 
 shall reduce the unavoidable guess-work to its lowest terms, and so save us 
 from the manifold hazards which result from not only guessing at facts, but 
 
THE COFFER-DAM PROCESS FOR PIERS. 2/ 
 
 at the effect of those facts. Whatever care we use we can never attempt 
 with success to fix the exact point where economy ends and extravagance 
 begins ; but what we can do is to establish certain narrow limits in either 
 direction, somewhere within which lies the truth, and anywhere outside of 
 which lies a certainty of error." 
 
ARTICLE III. 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 CONSTRUCTION AND TRACT ICE. 
 
 I/S HEN for some reason the necessary care has not been exercised 
 in the construction of a coffer-dam and in puddling it, or where 
 there were discovered conditions not known before the con- 
 struction began, which rendered the work unsatisfactory or 
 leaky, it will usually be found that the mode of repair which 
 seems most expensive will in the end prove the cheapest and 
 most expeditious. If the puddle proves leaky, and it be decided that the 
 material was of too porous a nature, the best remedy is to dig out and replace 
 it with better. Should it be found that the porous bottom had not been 
 removed to a sufficient depth, it may be found necessary to dig out the pud- 
 dle chambers and puddle deeper, or the leaks might be stopped by banking 
 up outside of the dam with clay or clayey gravel, or perhaps sand in sacks 
 would do some good. 
 
 Gravel will allow the percolation of water even where the head is small, 
 and when a pressure of from four feet upwards is brought upon it, the leak- 
 age becomes considerable and difficult to control, so that pure gravel is of 
 little service in stopping leaks. 
 
 Hay, straw, oats, crushed cane stalks, rotten stable manure, and similar 
 materials, mixed with the banking material, are very efficacious in pro- 
 ducing tightness, and when applied to local leaks will assist in closing them. 
 Where sheet piling have been used to exclude the water and leaks still 
 occur, they can often be closed by driving more sheeting to lap the cracks, 
 which may have been widened out lower down as the sheet piles were first 
 driven. This, we have seen, produced satisfactory results at Buda-Pesth, 
 where leaks were also closed by driving square timbers into the puddle to 
 compact it. 
 
 Clay can also be forced down through pipes directly to where the leakage 
 occurs. The use of this at the Government Lock at Sault Ste. Marie is de- 
 scribed in the Engineering News of September 26, 1896: "The only diffi- 
 culty encountered in the work of excavation was due to a leak in the coffer- 
 dam, which flooded the lock pit and delayed the work considerably. The 
 cause of this leak was found to be a crevice in the rock passing underneath 
 the coffer-dam, and despite all efforts to close it, the flow of water rapidly 
 enlarged the break until about fifty feet of the clay in the coffer-dam had 
 
 28 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 2 9 
 
 been washed away. The large break was closed by driving additional sheet 
 piling and filling in with brush, hay, and clay in sacks. This, however, 
 failed to entirely stop the leak through the crevice, and it was determined 
 to fill the cavity with clay. For this purpose a 3-inch pipe was driven down 
 through the coffer-dam until its lower end penetrated the crevice. In this 
 
 A. Cutting theClay Cylinders III Is 
 
 B. Inserting the Cylinders | ! !; 
 
 intoTheTutae. 
 
 C. ForcincjtheOay down 
 
 ' 
 
 V'sSBfikfe^. .'.:. .-rL ~- - 
 
 G.1y_ APPARATUS USED TO FORCE CLAY INTO CREVICE OF FOUNDATION ROCK AND 
 CLOSE LEAK IN COFFERDAM. 
 
 pipe small cylinders of clay about one foot long were placed and forced down 
 into the cavity by means of a plunger working in the pipe. The apparatus 
 is shown in the illustration (Fig. 17). As will be seen, the plunger, or ram- 
 mer, is an iron rod to the top of which is fastened a block of wood sliding 
 between the guides of an ordinary pile driver. The hammer of the pile 
 driver is the weight which pushes down the rammer. This apparatus was 
 
30 THE COFFER-DAM PROCESS FOR PIERS. 
 
 designed by E. S. Wheeler, engineer in charge of the work, and was used 
 not only to fill the crevice, but all along the coffer-dam for the purpose of 
 compacting the clay filling. The apparatus proved most successful for the 
 purpose for which it was intended." 
 
 The use of rods for bracing in double walled coffer-dams is very often the 
 cause of considerable leakage, the w r ater following along them through the 
 puddle. This may be stopped by wrapping a band of hay or straw around 
 the rod next to the timbers, or by a wrapping of coarse cloth, or by a wood 
 washer having a hole slightly smaller than the rod, which is forced through. 
 
 The walls of the dam must always be made tight, and this we have seen 
 to be effected by careful framing of sides and bracing, and it will be seen in 
 a later example how round struts between the two walls allowed the puddle 
 to flow around them and close up much better than if the braces were square 
 timbers. 
 
 The use of candle-wicking between the staves proved successful at Fort 
 Madison, and calking is very often resorted to at the first, and also to 
 close up local leaks. The use of this and the use of a stiff grease between 
 the layers of a crib will be referred to in another part of this article. 
 
 Th.e use of tarpaulins to make a watertight piece of work is described in 
 the Trans. Am. Soc. C. E., Vol. 31, by Montgomery Meigs, engineer in 
 charge of the government work at Keokuk, Iowa. "The upper one of three 
 locks was twice repaired by separating it from the river by an ordinary plank 
 and mud coffer-dam. But as this work had to be done after the close of 
 navigation, it was found to be very unsatisfactory on account of the freezing 
 of the puddle, and on one occasion the partly puddled dam froze and upset. 
 After this experience it was determined to use some other method than 
 puddle to produce tightness. There was available for drainage a 50-H. P. 
 suction dredge, with 14-inch suction, and a rotary Van Wie pump, and 
 plenty of 12-inch discharge pipe mounted on pontoons. It was proposed to 
 drain the lock with this dredge, allowing the boat to settle in the mud at the 
 bottom of the lock as the water left it, and to complete the work with a 3- 
 inch discharge Pulsometer. The lock being 350 feet long and 80 feet wide, 
 a flat place on the bottom was selected, the dredge placed over it and the 
 necessary length of discharge pipe placed in position on its pontoons. The 
 point selected for a bulkhead (Figs. 18 and 19) was just outside the lock 
 gates, about forty feet below the lower mitre sill, where there was a smooth 
 rock bottom, the ends of the dam abutting against the flaring ashlar wing 
 walls of the lock approach. 
 
 "The bulkhead was constructed with thirteen bents eight feet apart, of the 
 size timber shown, with light diagonal bracing. After being built 2^ miles 
 from the lock it was towed to position and sunk by weighting it with old 
 railroad rails, enough being used to overcome the buoyancy after the sheath- 
 
THE COFFER-DAM PROCESS FOR PIERS. 3 I 
 
 ing was added. A diver was employed to see that the bottom was clear of 
 obstructions and to guide the bulkhead to a solid bearing. The sheathing 
 was also guided to place by his assistance. 
 
 "The canvas sheet, which was designed to give tightness to the apron, 
 was of two breadths of ten feet and one breadth of six feet wide, sewed 
 together edge to edge for convenience, and about four feet longer than the 
 
 ^^ ; ^vy^^ 
 
 ,-, ^^o tvjw ' 
 
 Section / 
 
 - ' ^-^ ' " ~ ~ "'""" 
 
 FIG. 18. DETAILS OF CANVAS AND PLANK BULKHEAD. 
 
 extreme length of the apron. Some old j^-inch and ^6-inch chain was 
 sewed to one edge continuously to act as a sinker and insure the lower edge 
 of the canvas sheet hugging the bottom tightly. A few stones laid on it 
 would have answered the same purpose, but not so well. The canvas was 
 12-otince duck. 
 
32 THE COFFER-DAM PROCESS FOR PIERS. 
 
 "The sheet was spread under water by the diver. It lapped on the bot- 
 tom about twelve inches, covered the face of the apron and extended some 
 inches up the face of the wing walls at the end of the dam. Cleats were 
 nailed on the angle between the apron and the wing walls. These were of 
 Ix4-inch strips, nailed with 2-inch wire nails about twelve inches apart. The 
 upper edge of the canvas was also lightly cleated to the planking in a similar 
 manner. No other nails were driven in the canvas, which was designed to 
 be cut up into tarpaulins eventually. Where the plank touched bottom no 
 beveling was used, but one ragged hole was stopped with the beveled "stop 
 waters" which were made use of. The dam was pumped out in about six 
 hours and the leakage w r as so small that a 3-inch discharge pulsometer kept 
 out the water, and was then run only at intervals. Small leaks were stopped 
 by dumping rotten stable manure in their vicinity." 
 
 It is interesting to note that the bulkhead stood a pressure of twelve 
 feet of water. Experiments made to determine what pressure 12-ounce 
 duck would stand, show that the clean canvas begins to leak at two pounds 
 pressure, and at five pounds pressure the leakage becomes a marked amount. 
 With mud on the canvass the leakage becomes noticeable at from five to 
 seven pounds, and of a considerable amount at fifty pounds pressure, these 
 pressures being on a circle 4^ inches in diameter. The canvas did not 
 rupture at 800 pounds. 
 
 The suggestion is made to use an inverted funnel of canvas to stop the 
 leakage of springs on rock bottom. (Fig. 20.) The canvas to be spread out 
 over the bottom and weighted down with concrete, and the top wired to a 
 pipe into which the water may rise until the pressure head is overcome or 
 the pipe can be plugged. Arrangements of this nature, but without the 
 canvas funnel, have been frequently used. An iron pipe set on end is fitted 
 over the leak, and after concreting around to make it watertight, the water 
 rises inside until the pressure is balanced. A watertight wooden box may 
 also be used for the same purpose. 
 
 The founding of a new inlet tower in the Mississippi at the St. Louis 
 water works was accomplished by using a coffer-dam and it was the inten- 
 tion to form a junction with the bottom by using a canvas curtain. When 
 the coffer-dam was floated into position and the divers were sent down to 
 spread the canvas and weight it down with stones, it was found to be dam- 
 aged so as to be useless. This was supposed to be due to the action of the 
 swift current, but was most probably due to some accident such as fouling 
 on a snag or against a barge. 
 
 The anchoring of the crib for this dam is related in the Engineering 
 News of July 4, 1891. The dam was to be located near the head of a stone 
 dike about twenty feet in height and on solid rock bottom which was uneven 
 and worn into grooves by the action of the current, which had a velocity of 
 
THE COFFER-DAM PROCESS FOR PIERS. 33 
 
 between six and eight miles per hour. The bottom was leveled off by blast- 
 ing, to receive the crib, which was to be sunk in from fifteen to eighteen 
 feet of water. 
 
 The three triangular cribs shown (Fig. 21) were sunk and filled with 
 stone and were used to hold the dam in place while building and while 
 being sunk. Steel cables 1% inches in diameter were used as anchors. 
 
 The large crib also served as a protection from the current and drift. 
 
 The size of the crib was 38x74 feet outside and the height 22 feet. The 
 12xl2-inch yellow pine timbers were drift-bolted together with from one to 
 two feet spacing of bolts, and all the joints between the timbers were calked. 
 The bracing consisted of 12-inch square timbers, of which there were three 
 rows, the braces in each row being four feet apart vertically. These were 
 cut out as the masonry was built up and bracing against the stone work sub- 
 stituted. 
 
 There were four sets of diagonal bracing as shown. The space between 
 the walls, which was three feet, was partly filled with concrete in sacks, and 
 puddle placed on top. Sacks of clay were banked up around the outside, 
 and then the dam w r as pumped dry with a 10-inch pump. Inside was found 
 eight feet of mud and sixty sacks of concrete which had been washed there 
 by the swift current. 
 
 The amount of timber used was 125,000 feet, B. M., and about 12,000 
 feet of ^s-inch round iron for drift bolts. The puddle chamber required 
 1,000 sacks of concrete and 1,00 barge loads of clay, while 10,000 sacks were 
 used for banking up clay on the outside. This work was constructed under 
 the direction of C. V. Mersereau, Division Engineer, under S. B. Russell, 
 Principal Assistant Engineer. 
 
 The Queen's bridge at Melbourne, Australia, is a plate girder structure, 
 with four piers of eight cylinders each. The bottom was a reef of bluestone 
 which had been shattered by blasting and which was silted over with about 
 three feet of very soft silt. 
 
 The use of ordinary puddle coffer-dams was thought to be too expensive 
 as the bridge was 100 feet in width, and it was proposed to use a single wall 
 of timber protected by tarpaulins. The account of this work is taken from 
 the Engineering News of April 4, 1895, which is an abstract of a paper by 
 W. R. Renwick, engineer in charge. 
 
 To insure as light a construction as possible experiments were made on 
 the strength of Oregon pine, and it was found that tests of water soaked tim- 
 ber showed a loss of strength of as much as 33 per cent., when compared / 
 with tests of seasoned timber. The break, too, of the water- soaked pieces 
 was very short. This strength being the one adopted, a very low factor of 
 safety was used. A separate dam was constructed around each tube, but 
 with one side to open as a door to allow its removal and use for another 
 
THE COFFER-DAM PROCESS FOR PIERS. 35 
 
 place. The frame was made from 12x12 Oregon pine, with the sticks placed 
 closer together near the bottom to resist the greater water pressure, and 12x12 
 pieces were run up the corners, the frames being notched in. These also 
 served as spacers for the side timbers and as door frames. The sheeting on 
 the outside was of 4x12 rough timber, and outside of this at the top and 
 bottom were wale pieces, 6x12, bolted through the frames with 1-inch bolts 
 to hold the sheeting in place. 
 
 The tarpaulin was passed completely around the dam, being tacked to 
 the waling pieces, and so arranged as to allow the door to open. 
 
 When the dam had been placed around a tube the sheeting was driven 
 down to rock, through puddle which had been dumped on the bottom, and 
 
 FIG. 20. CANVAS FUNNEL FOR CLOSING LEAKS. 
 
 the pumping was readily done with pulsometer pumps. The only serious 
 leaking was where the 1-inch bolts passed through the joints between the 
 sheeting, but these were plugged with soft wood plugs, and in other work 
 the bolts were flattened to three-eighths of an inch where they passed 
 between the plank. The dams were removed by first drawing the sheeting 
 up to its original position, when the door was opened and the crib taken to 
 another tube. The depth of water was about fifteen feet, but while this was 
 successful in this instance, the method should not be copied unless the condi- 
 tions are favorable, nor unless the cribs are made practically watertight in 
 themselves. 
 
 This was the case in the above work, as one of the tarpaulins was acci- 
 dentally torn off and the dam still excluded the water, so that the tarpaulin 
 was only a wise precaution. Why the cylinders were not made watertight 
 
36 THE COFFER-DAM PROCESS FOR PIERS. 
 
 and used as their own coffer-dam is not stated, but this possibly could 
 have been done. 
 
 The use of tarpaulin in closing accidental leaks could doubtless be made 
 use of frequently, but as the sole dependence for producing tightness it 
 should be used with extreme care, in a gentle current and well protected 
 from damage. 
 
 The pivot pier of the Harlem Ship Canal bridge was founded in a 
 polygonal coffer-dam, from the plans of William H. Burr, consulting engi- 
 neer. The work is described in the Engineering Record of July 24, 1897: 
 "The rock bottom secured by the canal excavation being an acceptable sur- 
 face for the masonry of the pivot pier it was constructed in a polygonal 
 
 FIG. 21. CRIBS FOR ANCHORING ST. LOUIS COFFER-DAM. 
 
 double- walled coffer-dam with thirteen sides twenty-five feet high and sixty 
 feet in extreme diameter. The great dimensions of the coffer-dam would 
 have made it difficult to build and launch it on shore. Consequently it was 
 built partly on a detachable raft. As shown in the illustration (Fig. 23) the 
 inside wall was built up of timbers lapped and halved at the angles; the 
 outer wall timbers were carefully butt-jointed and secured by cross-struts 
 and 1-inch bolts to the inside walls. The rough-sawed horizontal surfaces 
 of the inner wall were bedded in stiff grease and the joints calked, which 
 notably resisted the penetration of the water. Each course of timber was 
 secured to the one below it by 24 -inch drift bolts spaced about four feet 
 apart. When the bottom was thoroughly cleaned the concrete was dumped 
 in place by a special steel bucket. Concreting was carried on night and day 
 
:J 
 
 n A r 
 
 o 
 
 ZQ Hd. Bottom to 
 H.W. 
 
 /2\IZ'-+*-6-/0'*U+*-J-8"x/Z-+ 
 Drift bolt,-, j'x/8" 
 about 3ft.a.pa.rt. 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 and was completed before puddling was begun. Considerable difficulty was 
 occasioned by the irregularities of the bottom which the coffer-dam could 
 not be made to fit closely. Divers were sent down and filled in bags of sand, 
 as at S, and riprap R was piled up outside to protect it. Then the space 
 between the walls was filled with puddle." 
 
 Another polygonal dam was constructed for the draw pier of the Arthur 
 Kill bridge, by Alfred P. Boiler, consulting engineer. The following 
 account is taken from Vol. 27 of the Transactions Am. Soc. C. E.: "It was 
 
 Halt '(Section Through Pier and Co/ftrc/Q/n 
 
 ~K 
 
 HALF -" C ^ HALF v 
 ELEVATION. SECTION. 
 
 FIG. 22. POLYGONAL COFFER-DAM, 
 
 HARLEM SHIP-CANAL 
 
 DRAW-BRIDGE. 
 
 PLAN. 
 
 FIG. 24. COFFER-DAM FOR PIVOT 
 PIER OF THE COTE A U 
 BRIDGE. 
 
 necessary to use as little space as possible for the dam, and to construct it 
 without interior bracing, so that a double-walled twelve-sided polygon (Fig. 
 22) with walls four feet apart in the clear was used. The rock bottom was 
 overlaid with two feet of clay and the clay with eighteen inches of sand and 
 mud, the depth of water over the rock being twenty-eight feet at high tide. 
 The square hemlock timbers used in the walls were halved together and the 
 walls braced together by bolts and round timbers for struts, the round tim- 
 bers allowing the puddle to run around them and pack well as thrown in. 
 
THE COFFER-DAM PROCESS FOR PIERS. 39 
 
 Clamp timbers 4x6, in two lengths, were held in place by the bolts and the 
 struts were braced against 6-inch plank. The dam was built to one-third 
 its height on shore, then towed to position and built up until grounded. 
 Between the timbers and the joints candle-wicking was placed, and the 
 courses drift bolted together every three feet and spiked at the joints. The 
 rock was dredged bare before placing the crib, which was filled with a hard, 
 gravelly clay between the walls after being sunk in place. A rich Portland 
 concrete was dumped inside, from triangular buckets, to seal the bottom 
 and then the dam was pumped out with a 6-inch pump and kept dry by 
 pumping at intervals. In one place the concrete was not thick enough and 
 a spring came up through a fissure in the rock. This was boxed in and led 
 to the sump. The material used was 140,000 feet of timber, 15,000 pounds 
 of iron, and 600 yards of puddle." 
 
 A piece of work similar to the Canadian Pacific example was an octag- 
 onal single- walled dam used in the construction of the Coteau bridge on the 
 Canada Atlantic Railway. This is illustrated in the Engineering 'Nc-cs of 
 May 30, 1891 (Fig. 24), and was braced thoroughly with cross-timbers built 
 into the sides. The bottom being of rock it was partly filled with concrete 
 to make it watertight. 
 
 The different forms of sheet piling will next be taken up, together with 
 pile driving machinery and the methods of driving both sheet and guide 
 piles. After this will be described the use of sheet piles for forming water- 
 tight coffer-dams, by reference to actual constructions of that character. 
 
ARTICLE IV. 
 
 THE COFFER-DAM PROCESS FOR PIERS.* 
 
 PILE DRIVING AND SHEET PILES. 
 
 N no department of engineering have ancient methods been more rigidly 
 adhered to than in that of pile driving. The form of the pile-driver 
 derrick has remained so characteristic that a person but slightly familiar 
 with the subject would have little difficulty in recognizing the pile driver 
 in the picture of Caesar's Bridge (Fig. 3) in the first article. The bridge 
 of the Emperor Trajan over the River Danube is an instance of the early 
 use of piles. This bridge was constructed in the first century, and when 
 the piles under water were examined in the eighteenth century they were 
 found in some cases to have become petrified to a depth of three-fourths of 
 an inch from the surface, beyond which the timber was in its original state. 
 Before derricks were used it is probable that piles were driven by a large 
 maul of hard wood, which is termed by Cresy a "three-handed beetle." The 
 block of hard wood was hooped with iron and had two handles radiating 
 from its center, to be worked by two men, while a third man assisted in lift- 
 ing it by means of a short handle opposite. 
 
 Wooden mauls are still used where sheet piling is to be driven into a soft 
 bottom, and heavy iron mauls or sledges are also used; but as has been fre- 
 quently stated such a soft bottom should be dredged and some more elab- 
 orate apparatus used to drive the piles into a harder substratum. 
 
 The most primitive form of the pile-driving derrick is similar to the one 
 used in 1751 by the celebrated French engineer, Perronet, at the brdige of 
 Orleans (Fig. 25). This was arranged with a number of small ropes splayed 
 out from the end of the lead line, so that a number of men could pull down 
 at one time, the drop of the hammer, of course, being limited by the reach 
 of the men's arms. The windlass shown was for the purpose of raising the 
 pile into place between the leads. 
 
 The same engineer improved upon this derrick by adding a large bull- 
 wheel to the windlass, on which was wound a rope to be pulled by a horse 
 from the side, as shown in Fig. 26, thus winding up the lead line on the 
 
 * The subject of pile-driving has been restricted to the ordinary methods and operations ; 
 such unusual processes as gunpowder pile driving and the like have not been .referred to. 
 
 Pile-driving, with the assistance of the water- jet, has been described on page 70, in the 
 account of the Sandy Lake coffer-dam. The ordinary operations of pile-driving, as practiced 
 on that work, are also described in some detail. 
 
 40 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 windlass. This same apparatus is in use down to the present time, except 
 that one seen recently had the windlass at right angles to the one illustrated. 
 
 The ram or Hammer used in olden times was of oak, bound with iron, 
 and weighed for the work at Orleans 1,200 pounds for the main piles which 
 were nine to twelve inches in diameter and which were driven three to four 
 feet apart, center to center, to a depth of six feet into the bed of the river; 
 the ram for the sheet piles only weighed half as much, the sheet piles being 
 about twelve inches wide by four inches thick. 
 
 At the bridge of Saurnur, which was built about the year 1756, De 
 
 FIG. 2o. PERRONET'S PILE 
 DRIVER. 
 
 FIG. 26. PERRONET'S BULL WHEEL 
 PILE DRIVER. 
 
 Cessart employed a driver with a bull-wheel, in the periphery of which were 
 set pins, to form handles for the men to pull upon and rotate the wheel. 
 Eight men, by making three turns of the wheel, raised the ram weighing 
 1,500 pounds six feet, when it was unhooked and allowed to drop. The piles 
 cost from two to five dollars each in place. 
 
 A very simple form of pile driver is shown in Fig. 27 and was described 
 in the Engineering News of March 16, 
 1893, by Julian A. Hall. The hammer 
 is hewed out of a section of a hardwood 
 log, and has pieces bolted on the sides to 
 hold it in the leads, which should give 
 plenty of clearance. The derrick was 
 constructed of very light timber, the ver- 
 ticals being 4-inch sawed stuff and the 
 bottom timbers 6x6 inches. The rope 
 passes over the sheave A and down over 
 the tops of the steps B B, on which the 
 
 men stand to pull the line and thus operate the hammer. This was a very 
 inexpensive apparatus and was found to work well. Where there is already 
 in use a heavier hammer of cast iron it can be used by striking light 
 
 FIG. 27. SHEET PILE DRIVER. 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 blows. The construction of the ordinary pile driver derrick is a simple 
 piece of framing, when good straight timber is easily obtained, the essential 
 features being to keep the leads free from any obstruction for the hammer and 
 to have efficient bracing. 
 
 For bracing a derrick under twenty-five feet a straight-back brace or 
 
 FIG. 28. PILE DRIVER DERRICK FOR USE ON A SCOW. 
 
 ladder having two horizontals running to the leads, and two side-braces will 
 be sufficient. But for a higher one, either additional long braces should be 
 used or diagonals introduced between the leads and the ladder. The use of 
 long braces is shown in Fig. 28, which is the design of pile-driver such as is 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 43 
 
 FIG. 29. LIDGER- 
 \VOOD PILE DRIV- 
 ING DERRICK. 
 
 used about harbors or rivers on heavy work. It would be mounted on a scow 
 or flat-boat sixty feet in length, twenty-five feet in width and of about six 
 feet in depth. The design of smaller derricks can be 
 approximated from this one, the bracing being used in 
 proportion. 
 
 It will be noticed that the guides for the hammer 
 are 4x4 inches lined with a steel plate. Two lines are 
 provided, one being for the operation of the hammer and 
 the other for pulling piles into place. Especial attention 
 is called to the hooks at A, as these are seldom shown in 
 the plan of a derrick and they are of constant use for 
 clamping and guiding piles. A timber laid across is 
 wedged tight against the pile to draw it to line, and can 
 be used to correct a stick which is beginning to slant 
 badly. Similar clamps of course are used on the oppo- 
 site side of the leads. 
 
 Where a pile begins to sliver or split in driving, if 
 the sliver is spiked down and the clamps used to hold it in 
 place, the trouble can usually be corrected before the pile is badly damaged. 
 The use of diagonal bracing between the leads and ladder is shown in the 
 Lidgerwood derrick (Fig. 29) in which a diagonal is introduced between each 
 pair of horizontals. This form of bracing is very satisfactory and equally as 
 good as the other method. The diagonals on a very large driver may be 
 extended over two panels and planks spiked down to the horizontals to form 
 a platform for the workmen. In smaller derricks the diagonal bracing is 
 most always omitted, dependence being placed in the stiffness of the leads 
 and the bracing from the ladder and horizontals, as was 
 done in the derrick shown in Fig. 4. 
 
 The power for driving with a small hammer weighing 
 from 500 to 1,500 pounds, may be furnished by laborers 
 pulling, but this is a slow operation and horse power is 
 nearly always used where steam is not available. The 
 power is furnished from a drum with a long lever, to which 
 the horse is hitched and winds up the hammer by walking 
 in a circle about the drum, the frame of which is firmly 
 fastened in place. This is called a "horsepower" apparatus 
 and works slowly, but is a cheap and satisfactor} 7 way 
 where a very few piles are to be driven. To the hammer 
 line are attached the tongs or nippers, which engage the pin in the top of 
 the hammer (Fig. 30), and when the hammer has reached the proper 
 height it is dropped by pulling a tripping rope and releasing the tongs, or if 
 the hammer is hoisted to the top of the leads, the top arms of the tongs are 
 
 FIG. 30. HAM- 
 MER WITH 
 NIPPERS. 
 
44 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 pushed together by the wedges on the leads and the hammer released auto- 
 matically. This is a slow method on account of waiting until the tongs run 
 down again and engage the hammer. The horse power, of course, has a 
 ratchet, so that the rope runs down free and usually the blows are hurried 
 by overhauling the line. With the addition of a hoisting engine all this is 
 changed and pile driving becomes one of the most stirring operations of 
 the contractor. When the hammer is hoisted up, the friction lever is released 
 and the hammer descends carrying the rope with it, as the tongs are done 
 
 FIG. 31. PILE DRIVING SCOW, NEW YORK STATE CANALS. 
 
 away with and the line attached directly to the hammer. A good engine 
 man will catch the hammer on the rebound and materially lessen the time 
 between the blows and likewise the cost of driving. 
 
 With a heavy hammer shorter drops are made, thus causing much less 
 damage to the pile, which would split badly under the high drop from the 
 use of tongs. For the smaller-sized hammers from 1,000 to 1,500 pounds 
 an engine of 10-horse power is mostly used, as it is usually thought best to 
 have a surplus of power in case ol need; while for a 3,000 pound hammer a 
 20-horse-power engine would likely prove the best and most economical, but 
 not infrequently a 25-horse-power hoist is employed. 
 
 The cost of an outfit will vary greatly and the only satisfactory way is to 
 get prices from responsible firms, but for preliminary estimates the cost of a 
 10-horse-power hoist with single cylinder and single drum may be taken at 
 about $900, and for a 20-horse power at $1,270. Preliminary prices for other 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 45 
 
 sizes of single cylinder, single drum hoists, may be obtained from the 
 formula: 
 
 Cost =i/81,000xhorse power. 
 
 The double cylinder engines will cost about 10 per cent, more and double 
 drums about 10 per cent, additional to this. 
 
 Pile driver derricks will vary much in cost owing to the location, on 
 account of the cost of timber, but a minimum cost for a first-class derrick 
 will be $6 per vertical foot and a maximum of $8. 
 Being such a simple structure the easiest and safest way 
 will be to make an estimate for each case. 
 
 In the selection of an engine it is well to remember 
 that with a double drum a second pile may be hoisted 
 into place, while the first one is being driven, as all der- 
 ricks are, or should be, provided with two sheave wheels 
 at the top for this purpose. While a single-drum engine 
 has a spool for this purpose, it cannot be used very satis- 
 factorily. 
 
 A pile driver on a scow is shown in Fig. 31, such as 
 was used in driving piles on the New York State canals. 
 Another pile is just being hoisted into position. The 
 hoisting engine has no protection, but a shed or house 
 is mostly provided as a protection from the weather. 
 
 While little change has ever been effected in the de- 
 sign of pile driving derricks, the adoption of steam hoists 
 was a great improvement, as \vas also the invention of 
 the steam pile hammer by James Nasmyth. The principle 
 is the same as that of steam forging hammers, and was 
 applied by Nasmyth to pile driving in 1845, the ham- 
 mers of this class bearing his name to-day. His idea 
 was that the drop-hammer was calculated more for de- 
 struction than for useful effect and he termed it the 
 "artillery or cannon ball principle." Besides this the 
 action of the drop-hammer even with the use of the 
 "monkey" engine was somewhat slow. 
 
 Samuel Smiles says that "in Xasmyth's new and 
 beautiful machine he applied the elastic force of steam 
 in raising the ram or driving-block, on which, the driv- 
 ing-block being disengaged, its whole weight of three 
 tons descended on the head of the pile, and the process being repeated eighty 
 times in a minute the pile was sent home with a rapidity that was quite 
 marvelous as compared with the old method. In forming coffer-dams for 
 piers and abutments of bridges, quays and harbors, and in piling the foun- 
 
 
 FIG. 32. WARRING- 
 TON - NASMYTH 
 STEAM PILE 
 HAMMER. 
 
4 6 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 dations of all kinds of masonry the steam pile driver was found of invalua- 
 ble use by the engineer. At the first experiment made with the machine 
 Mr. Nasmyth drove a 14-inch pile fifteen feet into hard ground at the rate of 
 sixty-five blows per minute. The saving of time effected by this machine 
 was very remarkable, the ratio being as 1 to 1,800; that is, a pile could be 
 driven in four minutes that had before required a day. One of the peculiar 
 features of the invention was that of employing the pile itself as the support 
 of the steam hammer part of the apparatus while it was being driven, so that 
 
 FIG. 33. WARRINGTON-NASMYTH HAMMER, FAIR HAVEN BRIDGE. 
 
 the pile had the percussive force of the deadweight of the hammer as well as 
 the lively blows to induce it to sink into the ground. One of the most 
 ingenious contrivances of the pile driver was the use of steam as a buffer in 
 the upper part of the cylinder, which had the effect of a recoil spring and 
 greatly enhanced the effect of the downward blow." 
 
 Many modifications of this hammer have been manufactured, and one 
 much used at present is the Warrington-Nasmyth hammer, made by the 
 Vulcan Iron Works. This hammer (Fig. 32) is made in three sizes, 
 the weight of the striking parts being 550 pounds for sheet pile work, 3,000 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 47 
 
 FIG. 34. CRAM-NASMYTH STEAM PILE HAMMER. 
 
 pounds for medium pile work, and 4,800 pounds for use on heavy work. 
 This machine is provided with a positive valve-gear, a short steam passage 
 to avoid the waste of steam, a wide exhaust opening to prevent back pres- 
 sure as the hammer drops, a piston-head forged on the rod, and channel bars 
 on the sides to allow the pile to be driven lower than the leads of the derrick. 
 The hammer is attached to the hoist rope, but this is left slack when the 
 hammer is resting on the head of the pile, steam is turned on and the ham- 
 
4 8 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 mer pounds automatically at the rate of sixty to seventy blows per minute 
 until the pile is driven. The bottom casting which rests on the pile is a 
 bonnet which encases the top and prevents brooming or splitting. 
 
 The hammer should have plenty of play in the leads, and the steam pipe 
 should extend half way up the derrick to save length of hose. This 
 
 FIG. 35. MACHINE FOR SAWING OFF PILES UNDER WATER. 
 
 hammer has a record of as high as seventy-five to one hundred piles per day, 
 and one account gives the record of 3,UOO lineal feet of piling per day at a 
 cost of $50, the number of men employed being sixteen and the coal con- 
 sumption one ton. This hammer is shown in Fig. 33 in use driving piles for 
 bridge work on the Fair Haven bridge. 
 
THE COFFER-DAM PROCESS FOR PIERS. 49 
 
 Another form of the Nasmyth hammer is the Cram (Fig. 34) which is 
 very simple in construction. The driving head is hollow and the steam 
 enters through a hollow piston rod, causing the head or cylinder to rise on 
 the rod. Four sizes are made, with hammers of 430 pounds, 2,000 pounds, 
 3,000 pounds and 5,500 pounds. The small hammer which is listed at $300 
 is used for sheet pile work by inserting a "follower" of oak which fits the 
 base or pile cap, and which has a slit in the lower end to fit the sheet pile. 
 The number of blows per minute is the same as other steam pile hammers 
 and an average of eighty-three piles per day of ten hours is reported, where 
 they were driven seventeen feet into sand and oyster shells in the Passaic 
 river, the largest day's work being 121 piles, or nearly double the best work 
 with an ordinary hammer. 
 
 Mention has been made of the use of a rock drill as a Nasmyth hammer, 
 on the Great Kanawah river coffer-dams; and where any amount of driving 
 is to be done it will certainly be wise to use a hammer of the Nasmyth type. 
 
 FIF. 36. PILE-PULING LEVER. AFTER CRESY. 
 
 The guide piles of a coffer-dam should always be driven with the idea of 
 using them as a support for pumps, engines, derricks, and the like, 
 although it will often be found cheaper to rig up on flat-boats when there is 
 danger from floods. In determining what load a pile will carry from this 
 source, or when driven as a foundation pile to support the masonry, Wel- 
 lington's formula is at once the most accurate and the easiest to remember 
 and use. For a drop-hammer, multiply twice the weight of the hammer in 
 pounds by the drop in feet and divide by the last sinking in inches plus one, 
 and the result is t he load in pounds the pile will carry, with a factor of six 
 for safety. This is easily remembered as 2 wh over s + 1, and is always 
 ready for use. For the steam-hammer the form is 2 wh over s+0.1, the 
 "wh" representing the dynamic effect of the hammer. 
 
 Where piles have been firmly driven and they are to be removed when 
 the work is done they can be cut off under the water by a machine similar to 
 Fig. 35, which can be operated from a barge. The description in the Engi- 
 neering News gives but little information in addition to the drawing. The 
 shaft works in cast-iron sleeves attached to a timber, which slides in the 
 
50 THE COFFER-DAM PROCESS FOR PIERS. 
 
 leads, this being operated by the winch shown in side elevation. The final 
 adjustment is made by the hand- wheel on the 3-feet adjusting screw. 
 Where the piles are not so solidly driven they can be pulled out with a lever, 
 an old form of which is given by Cresy (Fig. 36). In place of the pin and 
 links, a chain closely wrapped around the top of the pile is usually made 
 use of. 
 
 The apparatus used on the New York State canal work (Fig. 37) con- 
 sisted of a strong frame mounted on a scow, from which was suspended a 
 \eavy set of falls to attach to the chain wrapped around the head of the pile, 
 f he pulling was done by an engine placed on the scow. 
 
 The construction of coffer-dams with sheet piling has led to the use of a 
 
 FIG. 37. PII,E-PUI,IJNG SCOW, NEW YORK STATE CANALS. 
 
 number of forms of sheet piles, some of which are driven only as a protection 
 to the puddle, while others are nearly or quite watertight in themselves. 
 The principal forms are shown in Fig. 38, the simplest form being plarik of 
 some considerable thickness (a) for which Stevenson specified 4^ inches by 
 not exceeding 9 inches in width for the Hutcheson bridge. The points are 
 sharpened as at (i) so they will draw together in driving, and as at (j) to 
 cause them to drive straight and easy. The same principle is embodied in 
 the patent metal point shown at (k), which is used to protect the point when 
 driving through coarse gravel. 
 
 The piles at Buda-Pesth were increased to fifteen inches square in order 
 to resist the pressure brought upon the sides of the dam by the puddle, the 
 water, and also by the ice. Flat plank are also used by driving two or more 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 rows as at (b),. the second and third rows being used to close the cracks in 
 the main row of piles and retain the puddle. An example of this will be 
 given in the next article, where it was used on the Michigan Central Railway. 
 The extra rows may be of thinner plank if they can be driven. 
 
 Mention has already been made, incidentally, of the use of V-shaped 
 tongue and groove piling (c), on the Union Pacific Railway. This may be 
 
 I . I "A 
 
 
 V 
 
 FIG. 38. SHEET PII.ES AND SHEET PILE DETAILS. 
 
 made on a beveled saw table, the saw cutting half through the plank from 
 opposite sides at each cut. This will produce a reasonably tight wall, if 
 care is used in driving and if the points are sharpened to draw them together 
 and make tight joints. 
 
 Ordinary tongue and groove piling (d) is frequently used, but a more 
 frequent form is that shown at (e), like that used on the Robinson circular 
 dam. The two pieces forming the groove and the piece for the tongue are 
 
THE COFFER-DAM. PROCESS FOR PIERS. 
 
 FIG. 39; CHARLESTOWN BRIDGE. DRIVING WAKEFIEI.D SHEET PII.ING. 
 
 spiked to the 9x12 with 6-inch spikes sloping upward. A sheet pile dam 
 on another pier of the Arthur Kill bridge, employed piling in which the 
 grooves were made by making two saw cuts and cleaning out between with a 
 chisel, the tongue being formed in the same manner as at (f), the tongue 
 being spiked in one side. 
 
 A method which is not often employed is shown at (f) two grooves being 
 made in the sheet pile and a key driven after the piles are down. Should 
 the piles not drive in perfect line, and the groove fail to match, the method 
 will not be found to be a success. 
 
 Sheet piling formed of two or more plank bolted together is being exten- 
 tively used, one of them (g) being formed by two planks sawed with beveled 
 
THE COFFER-DAM PROCESS FOR PIERS. S3 
 
 edges and bolted together to form a pile similar to (c). This forms a pile 
 which will drive easily on account of having some size and which will 
 require fewer supports in the shape of waling pieces. 
 
 Several examples already given describe the use of Wakefield patent 
 sheet piling (h), the method of sharpening being shown at (h'). This is 
 constructed of three layers of plank from one to four inches thick, owing to 
 the pressure to be sustained. The center plank must be sized to keep the 
 tongue and groove uniform, and the plank are bolted together with six bolts 
 for a length of from sixteen to twenty feet, two bolts near each end and two 
 intermediate. For long piles, spikes should be driven between the bolts. 
 The bolts vary from f inch for 1-inch plank to 3^-inch for 4-inch plank. A 
 coffer-dam constructed with this piling is shown in process of construction 
 in Fig. 39, for the foundations of Charlestown bridge near Boston. A 
 description of this will be given in the next article. 
 
 Pile shoes for use on round or square piles are shown at (1) and (m), (1) 
 being patent forms. Straps of bar iron are used in many cases with suc- 
 cess, for main piles, and sheet iron of J /i -inch thickness, bent to a "V" and 
 spiked on, is often all that is necessary when shoes must be used on sheet 
 piles. 
 
 The thickness of sheet piling should be sufficient to prevent the plank 
 from bulging and should be calculated to stand a water pressure due to the 
 depth, and for a span equal to the distance between the waling timbers or 
 other supports. This would necessitate wales every six feet for 3-inch 
 plank under five feet head, or wales every three feet for a 21-feet head. 
 Plank 4y 2 inches thick would require wales every seven feet under a 9-feet 
 head, or every five feet for an 18-feet head. Timbers nine inches thick will 
 carry nine feet under a 20-feet head, while the 15-inch timbers of the Buda- 
 Pesth dam would carry twelve feet under a 33-feet head. 
 
 Good timber should always be employed if it can be procured, or if faulty 
 stuff must be used, allowance must be made by using thicker piles and by 
 placing the wales closer together. 
 
It 
 
 I**LT? 
 
 ARTICLE V. 
 
 THE COFFER-DAM PROCESS FOR PIERS.* 
 
 CONSTRUCTION WITH SHEET PILES. 
 
 ATER pressure against the sides of a sheet pile coffer-dam is 
 seldom provided for in an accurate manner, the thickness of 
 the piling being usually decided upon from past experience, as 
 is also the size and spacing of the guide piles and wales. 
 
 &-- , These are points where guess-work should be eliminated, as 
 
 otherwise good coffer-dams are often seen, where the pressure 
 
 has so bulged the plank as to cause leakage. While this may perhaps be 
 
 corrected by additional bracing, simple calculations may easily be made to 
 
 determine the size beforehand. 
 
 The pressure against a coffer-dam may act as at (a), Fig. 40, the sheet 
 piling being in the condition of a beam fixed at one end and loaded with a 
 gradually increasing weight, as shown by the dotted lines, due to the 
 pressure of water or puddle at 62 .4 pounds per cubic foot. Then the load on a 
 width w of the wall is 124. 8 w d 2 and the moment of the pressure is 83. 2 zv d* . 
 Taking the allowable unit stress on wet timber at 1,000 pounds per square 
 inch, the thickness / of the sheet piling may be obtained from the formula 
 
 in which d is to be taken in feet and the resulting value of / will be the 
 thickness in inches of the sheet piling. 
 
 This formula has been expressed in a graphic manner in diagram (d), 
 Fig. 40, from which, knowing the depth of water 2d, the thickness of piling 
 may be read directly without calculation. 
 
 The addition of a strut, as at (b), Fig: 40, places the sheet piling in the 
 condition of L beam supported at the upper end and fixed at the lower end, 
 but for practical reasons, it is best to consider it as merely supported at both 
 ends. The load will be the same as in the former case, 124.8 w d 2 , but the 
 
 * The assumption that the pressure of puddle will be the same as water-pressure is made 
 advisedly. It is true that very wet clay, approaching a fluid condition, will exert a much 
 greater pressure, but it would then be useless as puddle. Dry clay would exert a pressure 
 of less than half that due to water, so it has been assumed that wet clay or puddle would 
 exert the same force as water. Should it exceed it for a short time no damage would be 
 done, owing to the low unit-stress adopted. 
 
 54 
 
55 
 
 /0 
 
 4o 
 
 3 4 5 *6 ?. 5 9 /o 
 
 77i/c /r/\ e^5 Piling m lr\ct\ e5 . 
 
 &ZE PlL //V <5 . blA GRA A] (a ). 
 
 f. *>. 
 
 P/Z. IHG.blA GRA MS (btc). 
 
 W 
 
 $35 
 
 30 
 
 60 
 
 In 
 
 Q O O 
 
 5 
 
 3*t56?$9/0 ^ r v <r-^'o 
 
 (f) bbfance Between lVc?/e5 /A Feet . (ti)Po\iMi$ Per Square /ncA Allowabk, 
 (VALE5 FOP ffFT. cJP/4/V. TlMBEP OTPUT3 - IVE7 
 
 FIG. 40. ARRANGKMENT AND DIAGRAMS OF SIZES FOR SIIEKT-1'ILK COFFER-DAMS. 
 
56 THE COFFER-DAM PROCESS FOR PIERS. 
 
 maximum moment will occur at a point x which is a distance from the top 
 equal to 1.16 times d, and has a value of 32 iv d 3 . The thickness t may be 
 found from the formula 
 
 When the section of the plank to be calculated is located as ' V in (c) 
 of Fig. 40, it is in the condition of a beam fixed at both ends and loaded with 
 a uniform load m and a triangular load n. The exact analysis of this is too 
 lengthy to be taken up here, and reference may be made to page 195 of 
 "Wood's Resistance of Materials." 
 
 For practical purposes we may consider the load as all uniform and due 
 to the head acting at the middle of the span. This will give a load of 
 62.4 TV d s on the span 5 for a width iv y and a moment of 7.8 d 5 2 , which 
 gives a formula for practical use, for a unit stress of 1,000 pounds per square 
 inch of 
 
 t -- |/ .047 ds* 
 
 This is closely represented graphically in diagram (e) of Fig. 40, which may 
 also be used for case (b) by taking the depth of water to the middle of the 
 span. . For example, when the depth of water to the middle of the span is 
 15 feet, find this in the vertical column to the left, and if 6 -inch sheet piles 
 are to be used, follow the horizontal through 15 feet until it intersects the 
 6-inch curve and vertically beneath will be found the maximum spacing of 
 wales, 7 feet 3 inches. 
 
 The size and spacing of wales may be taken from a similar diagram (f) 
 of Fig. 40, which assumes the guide piles to be eight feet apart. The 
 spacing of struts or braces will vary so much, that the load must be calcu- 
 lated, and when this and the length are known the size may be calculated 
 from diagram (g) of Fig. 40, which is for wet timber. 
 
 From the formula 
 
 p = 600 1(1 d), 
 
 in which/ is the allowable stress in pounds per square inch, /is the unsup- 
 ported length in inches and d the least side of the stick in inches. 
 
 Where two rows of sheet piling are to be driven to form a puddle 
 chamber, if they are to be efficiently braced from the inside of the coffer- 
 dam, it will be sufficient to have a thickness of puddle of from two to four 
 feet to exclude the water, depending on the quality of the puddle. Where 
 there is to be no internal bracing, but two rows of sheet piling braced 
 together together and filled with puddle are to resist overturning, the com- 
 mon rule is to make the width of the puddle chamber equal to the height 
 above ground, up to 10 feet. When the height exceeds 10 feet, add one-third 
 of the excess height to 10 feet for the width. 
 
 When the puddle chamber becomes very wide it is often divided into 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 57 
 
 several compartments, as was shown in Fig. 5, and stepped in a similar 
 manner. When the bottom is rock overlaid with a thin deposit of clay or 
 gravel, the sheet piles may be driven around an open crib- work for support, 
 as was done at Harper's Ferry, on the B. & O. R. R. 
 
 Where guide piles are to be used, the waling pieces are framed in, as was 
 specified on the Hutcheson bridge, as shown at (a), Fig. 41, where the guide 
 piles are of sawed timber. The wales are spaced slightly farther apart than 
 the thickness of the sheet piles, to allow clearance in driving, the space 
 between the guide piles being filled out with a key pile to fill the panel 
 tightly. This method is but little used with tight piling, that shown at (b), 
 Fig. 41, allowing the piling to be driven continuously, by removing the 
 
 W IT TJ 
 
 (</) ORDINARY SHEET PILE GUIDES. 
 
 , 
 
 m 
 
 w 
 
 m 
 
 (l>) GUIDKS WITH SEPARATORS. 
 
 (c) SHEET-PILE CLAMP 
 
 FIG. 41 SHEET PILE GUIDES AND CLAMPS. 
 
 spacing blocks as they are reached, and substituting bolts through the sheet 
 piles, firmly connecting the piles and wales together, 
 
 A very satisfactory method is described in the Engineering Neiu s of 
 May 12, 1892, which was used by A. F. Walker. Having occasion to do a 
 large amount of work it was desirable not to go to the expense of squared 
 guide piles. Round guide piles (P) were first driven seven feet apart, and 
 cut off to a level. Caps were then drift-bolted to the tops, allowing them 
 to project slightly beyond the face of the round piles, thus forming a perma- 
 nent support for the top of the sheet piles. Near the ground line was placed 
 the clamp, consisting of two sticks (X) and (Y), connected by three bolts and 
 drawn together as tight as the intervening piles or pile and gauge block (G) 
 will permit. The stick (Z) is then forced forward by the wedges (W) until 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 59 
 
 the space between (Z) and (Y) is the same as the thickness of the piles. 
 The pieces (X) (Y) (Z) are slotted for the middle bolt, and this permits of 
 some adjustment. When one of the piles partially closes this slot, a notch 
 is cut in the same large enough to receive the bolt, and the bolt is then 
 slipped up to it and tightened. This allows of the next pile being driven as 
 close as the others. When one panel has been completed the nuts are 
 removed and the clamps moved forward to the next one, a notch being cut 
 in the end pile to receive the end bolt of the clamp. The piles are sharp- 
 ened flatwise with a little more slope on the side facing the guide piles, 
 giving them a tendency to drive away from the guide pile at the foot and 
 bear against the cap at the top. A slight bevel is also given to the edge to 
 make the foot crowd the adjoining pile. During the first half of the driving, 
 the joint is held a little open at the top, but during the latter half, pressure 
 
 FIG. 43 SEWER COFFER-DAM. BOSTON SEWERAGE SYSTEM. 
 
 is brought to crowd it toward its neighbor, and the joint will close as tightly 
 as possible. 
 
 The use of single pieces of timber as wales, against which the sheet piling 
 is driven, is illustrated in the use of method (b) of Fig. 38, by Benj. Doug- 
 las, Bridge Engineer of the Michigan Central Railway. The coffer-dam 
 (Fig. 42) was built without guide piles, the wales being 12x1 2-inch timber 
 bolted against the outside of the sheet piling, by the brace rods one inch in 
 diameter. The wales are held in place vertically by bracing of 2x1 2-inch 
 pine plank, which are spiked on as verticals and diagonals to form a truss 
 and also to stiffen the framework in general. 
 
 The sheet piling is 5x12, and after being driven into the hard gravel 
 bottom, the cracks were lapped by I -inch boards The bottom was uneven 
 
60 THE COFFER-DAM PROCESS FOR PIERS. 
 
 and accounts for the difference in height, the excavation at the high end 
 being dumped outside at the low end, to assist in making the dam tight. 
 The puddle chamber was 2 feet 8 inches wide and was filled with clayey 
 gravel. The plan also shows the grillage in place for receiving the founda- 
 tion courses of the stonework. This is formed by 12x12 timber crossed, and 
 drift-bolted together with 1-inch round and 18-inch long drift bolts. 
 
 The account of the Arthur Kill bridge foundation in Vol. 27 of the 
 ''Transactions of the American Society of Civil Engineers," by A. P. 
 Boiler, Consulting Engineer, covers a very interesting experience with sheet 
 piling on Pier No. 5: "This pier is near the edge of the marsh forming the 
 Staten Island shore, which is barely flooded at extreme high tides. Borings 
 indicated about thirty feet from the surface to hard bottom, consisting of 
 mud, mud and clay, clay and shale to the bottom of shaley clay, in which 
 the pier was to be founded. Experience on other work of a similar char- 
 acter, indicated that the founding of this pier would be accomplished with 
 little difficulty. The area of the foundations was inclosed with a tongued 
 and grooved sheet pile dam of 4-inch yellow pine plank. But it was found 
 impossible to hold the plank at a depth of fifteen feet, the mud and clay 
 becoming puddled with water, and despite all efforts at bracing, the plank 
 shoved inward to such an extent, as to spoil the whole dam before we were 
 half way down. A second dam was therefore driven around the first one, 
 but this time with 10xl2-inch tongued and grooved timbers, in one length 
 to reach the extreme bottom. These timbers were grooved by slitting the 
 grooves out at the mill with a circular saw and chiseling the blank so formed 
 free. The tongue was an independent spline, 2^x4 inches, of dry wood 
 and nailed in one groove. The timbers were shaped at the feet to drive 
 close. This dam was hard driving, but was finally accomplished, when 
 digging was resumed and the old dam removed piecemeal as we could get in 
 the braces. The bottom was reached within a perfect dam, with only one 
 bad leak in the northwest corner, due to the shattering of a small piece of one 
 tongue during the driving. As it was impossible to stop this leak from the 
 inside, and the outside was inaccessible, to prevent washing the concrete, 
 the leak was led off in a box at the side of the dam to the sump well, and 
 the footing course of concrete, filling the whole area of the dam about seven 
 feet deep, was gotten in place." 
 
 This example emphasizes in a very decided manner many of the state- 
 ments that have been made heretofore. While no doubt the removal of the 
 old dam was attended with much expense, its inclosure entirely within the 
 new sheet piling rendered the prosecution of the work comparatively certain. 
 
 An example of the driving of sheet piling on a slant, to prevent crowd- 
 ing in at the bottom is shown in Fig. 43, which is a cross-section of a sewer 
 coffer-dam used on the Metropolitan Sewerage Systems of Massachusetts by 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 61 
 
 Howard A. Carson, chief engineer, and described in the Engineering News 
 of Feb. 8, 1894. 
 
 The outlet into the ocean at 
 Deer Island begins at a point 
 about sixty feet inside the high 
 water line and about 1,850 lineal 
 feet is from five to ten feet below 
 high water. This necessitated 
 the coffer-dam, which was con- 
 structed with bents every six 
 feet and with 2-inch plank inside 
 the high water line, but for the 
 remaining distance of 4-inch 
 matched plank. The excavation 
 was done by means of buckets, 
 traveling derricks and dump cars, 
 the latter being emptied at the 
 sides and ends of the trench. 
 The leakage from the ocean was 
 kept out by using centrifugal 
 pumps, which pumped a maxi- 
 mum of 46,000 gallons per hour. 
 The concrete, which has large 
 boulders imbedded in its surface 
 the size of paving stones, was car- 
 ried up to the level of the ocean 
 bottom. 
 
 From the middle of June, 
 1893, when the work was begun, 
 to the end of September, 526 feet 
 of trench was completed. The 
 size of the trench was 14 feet 
 average depth and 10. 8 feet aver- 
 age width, which made the ex- 
 cavation average 5.6 yards per 
 lineal foot. The cost for the 
 trench, including coffer-dam, 
 sheeting left in and back filling 
 was $44.00 per lineal loot. 
 
 Casual mention has been made in several places of the use of Wakefield 
 sheet piling which was illustrated at h and h' of Fig. 38 and which is further 
 shown in Fig. 44. View No. 1 is of a corner which is formed as in the plan 
 
 44 _ WAKEFIELD SHEET PIWNG . 
 
62 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 No. 2, a tongue being bolted on the side of a pile, when the corner is reached 
 as in No. 3. Any angle is turned by a similar method, which is shown by 
 No. 4, or the piles may be driven to form a curve. The essential features 
 of the system ?re the triple lap or long tongue and groove which excludes 
 the water, and the use of ordinary plank, which can be easily obtained. 
 The center planks should be sized to a uniform thickness, to insure the 
 tongues fitting the grooves, and to make driving easy, while the three plank 
 are to be bolted and spiked together to cause them to act as a compound 
 beam and not as separate plank like the system of (b) Fig. 38. It is 
 recommended to use a 2^ -inch tongue on 1-inch boards and ^-inch bolts. 
 For 1^-inch plank a 3-inch tongue, for 2-inch and 2^-inch plank a 3%- 
 inch tongue and ^-inch bolts, while for 3-inch plank a 3^-inch tongue and 
 ^i-inch bolts are to be used, and the same size bolts for 4-inch plank, but a 
 4-inch tongue. Two bolts are to be staggered in every five to eight feet of 
 the length of the pile and spikes used between the bolts on long piles. 
 
 FIG. 45 TYPE OF MOMENCK AND HARPER'S FERRY COFFER-DAMS. 
 
 The La Grange lock on the Illinois river was inclosed with this piling, 
 under the direction of Major W. L. Marshall, Corps of Engineers. It was 
 intended to back the sheeting with earth, but as both dredges broke down 
 the water tightness was entirely dependent on the Wakefield piling, and 
 under a 7-feet head no leaks were developed. The piles were made of three 
 plank 3x12 inches by 22 feet long and with a 3-inch tongue; they were 
 driven by three pile drivers with hammers of from 2,800 to 3,000 pounds 
 through sand and mud, and in one place a layer of shells. There was no 
 difficulty experienced in driving the piles without special appliances. 
 
 The. use of 1-inch boards in this form (Fig. 45) is described by H. F 
 Baldwin, chief engineer of the C. & E. I. Railway: "In constructing our 
 second track over the Kankakee river at Momence, 111., it was necessary to 
 extend the piers in that river. The bottom is limestone and the surface is 
 very irregular. We tried several days and finally succeeded in constructing 
 a coffer-dam with two parallel walls of sheet piling. We then tried the 
 
THE COFFER-DAM PROCESS FOR PIERS. 63 
 
 Wakefield triple lap piling, constructed of 1-inc'i boards sharpened to an 
 edge, 2 ^-tongue and groove, which were driven with sledges until the piles, 
 which were soft pine, conformed to the uneven surface of the rock. This 
 piling was driven around cribs loaded with stone, and after the piling was 
 driven, gravel was put outside the coffer-dam, after which no trouble was 
 experienced in pumping out the water." 
 
 The work on the foundations of the new B. & O. R. R. bridge, over the 
 Potomac river at Harper's Ferry was similar in many respects to the above, 
 and the system was found to be very satisfactory. 
 
 Reference was made to the use of this piling on the Charlestown bridge 
 
 
 FIG. 46 COFFER-DAM ON CHARLESTOWX BRIDGE. 
 
 at Boston and the driving of the piles shown in Fig. 39. The work was 
 under the charge of Jno. E. Cheney, Consulting Engineer, and was success- 
 fully carried out. The piling were driven principally as forms for concrete 
 foundations and but little care was taken to make the dams watertight. 
 After the concrete was deposited they were used as coffer-dams against a 6 
 or7-feet head of water. They were 18 feet 6 inches by 119 feet (Fig. 46) 
 and in some cases were thirty feet below low water or forty feet below mean 
 high water. The piling was made of 2-inch plank and driven with an ordi- 
 nary pile driver. The pumping was done with a 20-inch centrifugal pump 
 
 OF TH* 
 
 UNIVERSITY 
 
64 THE COFFER-DAM PROCESS FOR PIERS. 
 
 and in some cases a 12-inch Follansbee pump of the propeller type was used. 
 The construction of the sewerage system at Fort Monroe, Va., under 
 Capt. Thos. L. Casey, Corps of Engineers, is described in the report of the 
 Chief of Engineers of 1896. The work was done on the general plans of 
 Rudolph Hering, Consulting Sanitary Engineer. One of the special diffi- 
 culties encountered "was the building of a sewage tank fifty feet in diameter, 
 with walls of brick two feet in thickness, exteriorly diminishing to three 
 feet at the center, the inferior reference of which was twenty feet below low 
 water. As described in the report referred to, this was accomplished very 
 successfully by excavating a large area to the reference of ground water, some 
 five or six feet below the surface, and then driving by the pile driver and 
 water jet combined, two concentric twelve-sided polygons of Wakefield sheet 
 piling 28 feet in length, 30 and 22 feet from the center, about the circumfer- 
 ence of the shallow excavation. (Fig. 47.) The material, consisting of fine 
 water-soaked sand, with a small admixture of clayey matter and fine gravel, 
 was then excavated between the polygons to a reference of 20 feet, trans- 
 verse shoring braces bearing upon stout stringers being put in at intervals 
 as the work proceeded. The material did not vary much in its general 
 nature, but a number of old piles were taken up, some of which did consid- 
 erable injury to the sheet piling when driven, as shown in the subsequent 
 excavation. The water was controlled by a powerful steam pump having 
 its point of suction fixed, the water being permitted to flow toward it through- 
 out the circumference. It was noticed that ground water came through the 
 sheeting very freely at first, but that it constantly ceased to flow to any 
 great extent at a height of a few feet above the point of excavation as this 
 continually descended, owing to the rapid drainage of the strata. The 
 interior core, in fact, t ecame quite dry, so that in excavating after the walls 
 were laid, no water was encountered until the bottom of the external concrete 
 ring had been virtually laid bare. Upon attaining the reference 20 feet, 
 the excavation ceased and hand-mixed concrete was deposited directly upon 
 the bottom . as this was considered to be sufficiently firm, the pump being 
 stopped temporarily in order to prevent a flow. The concrete was rammed 
 firmly against the outer sheeting externally and against plank forms with 
 triangular cross-section resting against the inner sheeting internally, until 
 six feet in depth had been put in place. The portion of the ring at the 
 pump suction was filled rapidly with concrete in bags. The 2-feet brick 
 wall was then carried up from the axia) line of the concrete ring, the space 
 between the wall and the outer sheeting filled with sand, except about six 
 inches at the base of the wall, which was of concrete. The braces were 
 removed as successively attained, the inner prism of dry sand being held 
 securely by the sheeting and the extreme top struts, which were left in place 
 until the inner core was completely excavated. On the completion of the 
 latter work to reference 20 feet, the water which came in freely from with- 
 
THE COFFER-DAM PROCESS FOR PIERS. 6$ 
 
 out under the concrete ring at several points was conducted in a peripheral 
 trench to the fixed point of pumping. No water came upward and the 
 middle portions of the bottom became perfectly dry. The inner .sheeting 
 was cut off at the base of the ring, boards were placed transversely over the 
 peripheral trench, a duck tarpaulin coated with hot asphalt laid down, 
 and concrete rammed in place until the concave bottom with sump 
 channel had been completed, leaving only the pipe, through which 
 the ground water had been pumped continually, night and day at about 1,000 
 gallons per minute, penetrating the concrete. In order to fill this pipe, it 
 was cut off above the level of permanent ground water, and after the water 
 
 FIG. 47. RESERVOIR COFFER-DAM. FORT MONROE, VA. 
 
 within had attained the level of ground water in the surrounding area and 
 had become perfectly quiescent, neat cement in paper bags was dropped 
 within, being retained at the bottom by the closed valve; the bags were 
 readily broken up by a long pole thrust down the pipe. The latter was then 
 cut off at the level of the bottom and a coating of cement plaster applied 
 throughout. The resultant leakage through the bottom did not exceed about 
 a gallon a minute and this will be greatly reduced by the infiltration of sand 
 from beneath." 
 
 Further illustrations of the use of sheet pile coffer-dams will be given; 
 then the operations of dredging, pumping and concreting described at some 
 length. 
 
ARTICLE VI. 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 CONSTRUCTION WITH SHEET PILES. 
 
 VARIOUS combinations of the sheet piling shown in Fig. 38 may be 
 made, when occasion demands, or modifications may be made 
 that will perhaps render the available material more effective. 
 For example, the form (g) may be modified to the form shown in Fig. 48, 
 which has the advantage of a wider lap, and should the piles not draw 
 tight together in driving, no crack will be left open to admit the water. 
 Then the piles of this form will act as guides to the ones being driven, 
 similar to the ordinary tongue and groove piling. Other combinations and 
 arrangements will readily suggest themselves as necessity may demand. 
 
 The use of sheet piling is often accompanied by a great deal of trouble 
 in producing tightness, and as a matter of precaution, the very best method 
 possible should be adopted in making the piling. 
 
 The coffer-dams constructed at Chattanooga for the Walnut street bridge 
 over the Tennessee River, under Edwin Thacher, Consulting Engineer, were 
 described in the Engineering A r ews of May 16, 1891. 
 
 Four piers were founded by this method, but the account of pier number 
 two will fully illustrate the work. The bed rock which was level, was 
 covered by cemented sand, gravel and boulders, of which 320 yards were 
 removed. The coffer-dam was built eighteen feet high, or eight feet above 
 low water, to provide for a future rise. The inside was made large enough 
 to allow of a space of four feet all around the base of the pier, and the 
 space between the sheet piles for a puddle chamber was made nine feet. 
 This was filled to an average of twelve feet with a clay puddle, of which 
 there was 900 yards used. As a protection, there was placed outside the 
 dam about 450 yards of puddle, and a breakwater was built up stream. 
 About 38,000 feet of timber was used in the dam and breakwater. 
 
 After the dam was completed a rise of thirty feet washed out about half 
 the puddle, and one end was crushed by a raft, but the repairs were made 
 v\'ithout serious trouble. No extra amount of pumping was required on any 
 of this work except pier number three, where the seams in the bed rock re- 
 quired pumps with a capacity of 5,000 gallons per minute, and these did 
 not suffice to keep the water down, until the seams were closed by laying 
 sacks of concrete over them and weighting them down with large stones. 
 The location of these seams is shown in Fig. 49. 
 
 The framework and wales for a sheet pile coffer-dam, used in founding 
 
 66 
 
THE COFFER-DAM PROCESS FOR PIERS. 67 
 
 the pier for the Baltimore street bridge at Cumberland, Md., are shown in 
 Fig. 50, and this was described in the Engineering News of July 21, 1892, 
 by H. P. Le Fevre, engineer in charge. The frame was built in place on 
 two canal-boats and after completion was suspended from the old Bollman 
 truss which the new bridge replaced. 
 
 The depth of the water was four feet, and about six feet of very loose 
 quicksand and small round pebbles overlaid the hard bottom. 
 
 After the boats were removed, the frame was lowered to its place, the 
 sheet piling driven and the dam pumped out with a six-inch pump. The 
 foundation was laid on the hard bottom under the quicksand, after this had 
 been removed. 
 
 The grillage was made of two courses of 15x1 5-inch clear white oak, 
 around which was built a framework, and the open spaces of the grillage 
 were then filled with a concrete, made up of one part of Cedar Cliff cement 
 to two parts of sand and four parts of hydraulic limestone, broken to pass 
 
 V \ 
 
 II I, \ 
 
 !! i \ 
 
 
 n ' 
 
 n I 
 
 FIG. 48 COMPOUND SHEET PILE. 
 
 through a two-inch ring. Upon this was laid the footing courses of the 
 masonry. 
 
 Another ordinary sheet pile coffer-dam which gave good satisfaction, 
 was used at the Sandy Lake dam on the Mississippi River, by Major W. A. 
 Jones, corps of engineers, and as the account contains so much of value, it 
 will be quoted in full from the 1894 report of the Chief of Engineers. 
 
 "The coffer-dam is composed of two rows of round piles, twelve feet 
 from center to center of piles, with the exception of sixty-two feet of the 
 east end of the upper part, where they were driven fourteen feet from center. 
 The piles in each row are eight and one-half feet from center to center, cut 
 off at an elevation of 1217 feet above sea level and capped with 12x12 inch 
 timber. The inside row of sheeting is 4x12 inch, and the outside 6x12 inch 
 plank. The sheeting is cut off at an elevation of 1218 feet above sea level, 
 or two feet below the flowage line. One-inch rods of round iron, eight and 
 one-half feet apart, pass through the caps to prevent the filling from 
 spreading the two lines of sheeting at the top. 
 
 In May, 1892, when a flood occurred, the outside of the cofferdam was 
 raised three feet by splicing three-inch planks to the outside row of sheet- 
 
68 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 ing and then filling the triangular prism thus formed with earth. The cross 
 section of Fig. 51 gives an idea of the dam above the bottom, while the 
 longitudinal section shows the framing down to where it rests on the bot- 
 tom, the frames being joined by the one-inch lateral rods of iron. 
 
 The total length of the coffer-dam is 829 feet, of which 742 feet is like 
 that shown in cross section and the other 87 feet like that shown in the 
 longitudinal section. 
 
 The number of round piles driven in the foundation is 1.605. The driv- 
 ing was commenced on November 12,1891, and completed on August 2 1 , 1 893 . 
 
 The material in the foundation is sand, excepting in the lower right 
 hand corner, where there is some blue clay overlying the sand. The sand 
 in the foundation is not as compact as it is usually found in the bed of 
 streams. In the south half of the dam, the surface settled from four to six 
 
 EI.O 
 
 EI.-S 
 
 1 
 
 
 
 
 I 
 
 
 
 1 
 
 
 
 
 
 \ Bed of River. 
 
 
 ivest. 
 
 fast 
 
 FIG. 49 CHATTANOOGA BRIDGE BED ROCK PIER NO. 3. 
 
 inches during the driving. As the surface was settling, the driving became 
 harder all the time. In the north half, which embraces the navigable pass, 
 there was some settlement, but it was not as noticeable as in the south half. 
 The surface had probably settled by the jarring of the hammers while the 
 first half was being driven. The penetration of the piles is also greater 
 than it usually is in sand foundations in the bed of streams. 
 
 The piles were all of Norway pine and well seasoned. Two Mundy 
 steam hoisting engines were used in driving, one a single cylinder and the 
 other a double cylinder engine. In operating the hammer an inch and a 
 half manila rope was attached to the pin connecting the lugs of the ham- 
 mer, then passed over the sheave at the top of the leaders, and next around 
 the drum of the hoisting engine. 
 
 When the hammer falls, it pulls the rope with it and unwinds it from the 
 drum. This is what is termed driving with a "slack line." The blows are 
 
;o 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 more rapid and keeps the material around the piles looser than it would be 
 in the case of using nippers. Iron rings of 5/gx2^ inches Norway iron 
 were used to protect the head of the pile. 
 
 It is a well-known fact in pile driving that it is very important to keep 
 the material from settling around the pile, once it has been loosened, until 
 the pile is down; for when the material has settled, or even partially, the 
 penetration is diminished. The greatest load on a bearing pile is about 13^ 
 tons. 
 
 Sheet piling was driven by a pile driver, assisted by a jet of water from a 
 steam force pump. In driving all sheet piles a cast-iron cap or follower was 
 used which fitted over the head of the pile. On the upper side of the fol- 
 lower there is a wooden block of some seasoned or close grained wood which 
 receives the blow of the hammer. This device saves the head of the pile 
 from being battered or splintered, and the pile can be driven to a greater 
 depth than it could be without it. 
 
 '21' 
 
 m 
 
 FIG. 51 SANDY I.AKE COFFER-DAM. 
 
 In first using the jet on a sheet pile, a groove was made in the inner 
 edge to receive a half-inch gas pipe, which was connected to the force pump 
 by means of an inch and a half hose. The aperture at the lower end of 
 the gas pipe was reduced to a diameter of about three-eighths inch. The 
 water was thus forced to the bottom of the pile, and the sand loosened. 
 
 This worked well until the sheet pile struck gravel, when the nozzle of 
 the pipe would become battered or filled with gravel. The pressure in the 
 hose would then burst a coupling somewhere. Another source of trouble 
 was the frequent breakages in the connection between the pipe and the 
 hose, on account of the jarring of the hammer. This plan after awhile was 
 abandoned and the nozzle of the pipe was thrust by hand under the point of 
 the pile. The piles are driven in the ground from 12 to 14 feet. 
 
 The construction of the Main street bridge at Little Rock, Arkansas, in- 
 volved the construction of two coffer-dams, for piers No.. 5 and No. 6. This 
 work was done under the direction of Edwin Thacher, Consulting Engineer, 
 whose original specifications called for pile foundations for these piers, the 
 piles to be driven to bed rock and cut off four feet below low water, to re- 
 ceive a grillage of 12x1 2-inch timbers to receive the masonry. The size of 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 FIG. 52 COFFER-DAM AND CONCRETE PIER, LITTLE ROCK, ARK. 
 
 the grillage being 12 and 13 feet wide by 34 feet long and resting on forty- 
 eight and sixty piles respectively, the piles being of good sound oak or pine 
 at least eight inches in size at the small end and not less than twelve inches 
 at the butt when sawed off. 
 
 The coffer-dams were constructed, as can be seen from the view in Fig. 
 52, by driving guide piles, to the top of which are drift bolted square guide 
 timbers. The sheet piling of three-inch tongue and groove stuff was driven 
 against the outside of this timber, and the excavation banked up against 
 
72 THE COFFER-DAM PROCESS FOR PIERS. 
 
 the outside. They gave excellent satisfaction and caused little trouble as 
 the water was shallow. 
 
 The piers were constructed of Portland cement concrete, the facing of 
 two inches thickness being a mortar of one part of cement to two parts of 
 sand while the balance was of concrete of one part cement, three parts sand 
 and six parts of broken stone. 
 
 Where sheet piles are to be driven on rock bottom or through earth or 
 gravel to rock bottom, they should be driven hard enough to broom up and 
 form a close joint with the rock. This has been accomplished also by driv- 
 ing the piles with a thin edge until they fit the rock bottom, when they are 
 drawn and after cutting them to conform to the contour of the rock, they are 
 redriven, thus forming a tight joint. This method while very good, is too 
 expensive for general adoption. 
 
 Coffer-dams are quite frequently constructed for the repair or removal of 
 existing piers. A pier which was constructed in 1840 in the river Parnitz, 
 at Stettin, Germany, became an obstruction to navigation and it was de- 
 cided to remove it. . The work was described in the Engineering News of 
 July 14, 1892. 
 
 Its exterior showed a facing of granite laid in hard Roman cement, and 
 soundings revealed the existence of a course of sheet piling around the pier, 
 with a protection of rip-rap at its foot. The original drawing of the pier 
 showed a pile foundation. The specification prescribed the use of the old 
 course of sheet piling, shown at A on accompanying cuts, for the construc- 
 tion of the coffer-dam. Owing to the belief that the existing sheet piling, 
 after having served such a length of time, would not be sound enough to 
 permit of its use in the erection of a coffer-dam, local contractors could not 
 be found and the work was let to an outside contractor. 
 
 The preliminary work was begun by picking up the rip-rap around the 
 foot of the pier with a claw dredger mounted on a raft. Some of the stones 
 weighed as much as a ton. The bottom of the river, after the rip- rap had 
 been cleared away, was found to be covered with a layer of concrete, consist- 
 ing of pieces of brick and cement. This was brought up in large slabs. The 
 pier itself was found to be of rubble masonry, composed of irregular shaped 
 granite blocks with the interstices filled with brick, laid in cement mortar. 
 The single stones were detached and swung off by the claws of the dredger. 
 Their average weight was about one and a half tons. 
 
 After the masonry had been pulled down to nearly the level of the water 
 a row of sheet piling, shown at b in Fig. 53, consisting of piles seven inches 
 thick, was driven to a depth of nearly ten feet. The space between the old 
 and new sheet piling was filled with blue clay. To keep the interior free 
 from water two pumps were employed. After putting in the necessary 
 bracing the work of removing the masonry to the bed of the river was con- 
 
THE COFFER-DAM PROCESS FOR PIERS. 73 
 
 tinued. A shell of the latter, however, was left standing. Then the timber 
 platform on which the masonry had been resting and the layer of concrete 
 below were taken out, exposing a layer of clay underneath. While attempt- 
 ing to pull one of the foundation piles a stream of water rushed through the 
 opening thus formed, so that this plan had to be given up and blasting re- 
 
 cJecr/orT, ReaUy for D'asting. 
 
 Sectfot\ f OriOir\Ql Pier. 
 
 Z6' 9" 
 
 Plor\, R?<3dy for Blasting^. 
 
 FIG. 53 REMOVAL OF MASONRY PIER AT STETTIN, GERMANY. 
 
 sorted to. To do this the tops of the piles were bored to a depth of thirteen 
 feet and filled with 8.8 pounds of dynamite each. The initial charges con- 
 sisted of 10.6 ounces in air-tight canisters. The shell of masonry left stand- 
 ing received four cubical charges of 8.8 pounds each. In all sixty-eight 
 charges, consisting of 616 pounds of dynamite, were used. The electric 
 current for the blast was divided into three currents, each being attached to 
 
74 THE COFFER-DAM PROCESS FOR PIERS. 
 
 an induction apparatus. The blasting, however, did not prove to be as 
 effective as was anticipated, owing to the dissolving action of the water, and 
 several charges were taken out intact. The clearing away of the wreck was 
 almost entirely done by the claw dredges. The piles, which were split and 
 loosened in their sockets by the force of the explosion, were pulled up by 
 windlasses mounted on flat boats. The work of removing the pier lasted 
 nearly nine months and the cost was about $8,700. 
 
 Another example of the removal of a pier was at Gadsden, Alabama, 
 where a pivot pier in the Coosa river had tilted. The pier had been built 
 originally in a water-tight caisson and was supposed to have been founded 
 on solid rock, but by some error a layer of gravel was left underneath and 
 eventually the pier tilted down stream seven feet, nearly throwing the swing 
 span into the river. 
 
 After the span had been blocked up to allow the passage of trains, a coffer- 
 dam was built around the pier to give plenty of clearance to the old caisson. 
 (Fig. 54.) This was constructed by driving three rows of sheet piling 
 through sand and gravel to bed rock and puddling between them. 
 
 The sand and gravel over the rock was not removed from the bottom of 
 the puddle chamber before puddling and a great deal of trouble was expe- 
 rienced all through the work by leakage through the porous gravel. It is 
 probable, too, that a poor joint was made between the sheet piling and the 
 rock. 
 
 Bents were erected upon the sides of the coffer-dam and by driving piles 
 into the puddle and inside the dam, to carry a truss on each side of the 
 span, which carried the drum and supported the main trusses at the center. 
 When this had been tested by loading with trains of ore upon the bridge 
 and found to be satisfactory, work was at once begun upon the removal of 
 the old pier, by means of two fixed derricks on the false work and one float- 
 ing derrick. The stones were marked as they were removed to insure their 
 return to proper places when the pier was rebuilt, and were taken to the 
 shore until needed again. When the masonry was all removed the grillage 
 was broken up and taken out, after which the gravel inside the coffer-dam 
 was cleaned out down to bed rock. New footing courses were laid to take 
 the place of the gravel and old grillage, and the old stonework relaid by 
 placing each course in its former position as nearly as possible. The pier 
 was about 80 feet high and contained about 1,100 yards of masonry. The 
 work occupied from Sept. 15 to Dec. 25, 1888, and was done under the di- 
 rection of Cecil Frazer. The description is tiken from the Engineering 
 News of April 13, 1893. 
 
 The construction of the piers for the Philadelphia and Reading railroad 
 bridge over the Schuylkill, was accomplished by the use of a floating coffer- 
 dam, the foundations being laid upon the bed rock. 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 75 
 
 When in position for work the dam is rectangular in shape, 62 feet long 
 and 36 feet wide, outside dimensions, and 16 feet high. Each side consists 
 of timber crib work 10 feet wide, making the inside dimensions 42x16 feet. 
 At each corner there is a movable timber extending vertically from the bot- 
 tom of the crib to some distance above the top. These timbers or spuds 
 are shod with iron on the bottom, and serve to hold the dam in position 
 while the sheet piling is being driven. The dam is divided vertically 
 
j6 THE LOFFER-DAM PROCESS FOR PIERS. 
 
 through each short side into two equal parts, which can be floated separ- 
 ately to any desired position and afterwards joined together. Watertight 
 compartments are built in each section to assist in floating it, and these com- 
 partments are also used to hold stone when it is desired to sink the cribs. 
 
 When the two sections are united and placed in required position the 
 spuds are dropped and the crib work is sunk by letting water into the water- 
 tight compartments, and putting in the necessary amount of stone. 
 
 Any irregularity in bearing between the bottom rock and the bottom of 
 the crib is then corrected by a diver, who blocks up where required. Close 
 sheet piling of jointed plank three or four inches thick is then put on the 
 outside and spiked to the cribs. Puddle, composed of clay and gravel, is 
 then thrown around the bottom outside, and the dam is ready to be pumped 
 out. When the masonry reached the height of the braces they were taken 
 out and the dam was braced against the masonry. 
 
 The maximum depth of water encountered at Falls bridge was thirteen 
 feet at ordinary water level. Several freshets occurred during the progress 
 of the work which did some damage to the dam. At one time, when a dam 
 was ready to be pumped out, a rise in the river moved it down stream about 
 thirty feet, tearing off the sheet piling. It was drawn back to place and 
 successfully completed. To make a complete shift of the dam from one 
 pier to the next, with a gang of six men, required about six or eight days, 
 divided as follows : To take the dam apart and reset it, about three 
 days ; to sheet pile, about two days ; to puddle, about one day ; and pump- 
 ing, out and puddling meanwhile required about one to two days, 'depending 
 on the amount of the leakage. At each shift, a portion of the plank sheet 
 piling, perhaps 10 per cent, had to be replaced by new stuff. The pump 
 tised was located on a small steamboat, and was run by a steam engine. The 
 amount of pumping required after the dam was once pumped out varied for 
 the different piers ; some dams required little pumping and others a good 
 deal. Only one of the foundations required much leveling off of the river 
 bed, and this one also gave considerable trouble to keep the water out, but 
 the leaks were finally stopped by using gunny bags around them ; the bags 
 being drawn into the crevices by the force of the water, thus holding the 
 puddle. 
 
 The floating dam was used for the three piers in the river channel, the 
 two piers near the shore being put in with ordinary dams. The floating 
 dam is still in good condition and could be used again if needed. The 
 original dam of which the one used at the Falls bridge is an enlarged copy, 
 was used for twenty-three or twenty-four settings. 
 
 The foregoing account is taken from the Engineering News of May 24, 
 1S94, the description being by W. B. Riegner, who states also that the cost 
 of the coffer-dam, including one set of sheet piling, was $3,000, while the 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 total cost for five coffer-dams, including the two crib coffer-dams at the 
 sides of the river, was $14,000. 
 
 The subject of subaqueous foundations has been very fully treated of 
 in a series of lectures by W. R. Kinipple, M. Inst. C. E., before the Royal 
 Engineers' Institute at Chatham, England. 
 
 The use of six-inch pitch pine close sheeting was made use of by him, 
 for a quay wall in the harbor of St. Helier, Jersey. They were driven to 
 rock or as deep as possible with a 2,800-pound hammer, and the tops cut 
 off a few feet beneath half tide level, and clayey material banked up 
 against the outside. The bottom through which the sheet piles were 
 driven was sand and clay. 
 
 The rock was laid bare to a depth of as much as thirteen feet below 
 low water and in sections which contained about 900 tons of water to be 
 pumped out ; this was done with a sixteen-inch centrifugal pump in about 
 forty-two minutes. 
 
 Several leaks were developed under the piles, but 
 they were promptly stopped by "stock ramming." 
 The stock rammer which is shown in Fig. 55, is 3 
 inches in diameter, 3^ feet long and banded top and 
 bottom with iron. A ^-inch air hole is bored up 
 from its foot a distance of twenty to thirty inches, 
 and covered on the bottom with a sole leather flap, so 
 that air is let in and suction prevented as it is with- 
 drawn. The sheet piles have 3^ -inch holes bored 
 through their sir 1 as, and cylinders of clay are inserted 
 3x9 inches long, similar to the work at Sault Ste. 
 Marie. The stock rammer is inserted and driven by 
 mauls as far as its length will permit when it is 
 drawn out, and other charges inserted until no more 
 clay can be driven. The hole in the pile being filled with a wooden plug. 
 
 The piers for the Putney bridge, over the Thames, were built by the 
 same engineer, with single pile dams to a great depth, by using fourteen- 
 inch square piles, with elm wood tongues, and driving them down through 
 the mud and clay to the stiff clay bottom, so that practically watertight 
 work was secured 
 
 In the construction of the docks at Victoria, British Columbia, he con- 
 structed a coffer-dam 500 feet in length, in a depth of thirty-five feet of 
 water, the bottom being of rock and overlaid in places with sand and shells 
 several feet in thickness. At the center the sand and shells overlaid a bed 
 of clay. 
 
 Three rows of close 12xl2-inch sheet piling were driven with two puddle 
 
 iron 
 
 coUat- 
 
 FIG. 55 STOCK 
 
 RAMMER. 
 
78 THE COFFER-DAM PROCESS FOR PIERS. 
 
 chambers of seven feet each between. The guide piles were 15x15 inches 
 and the wales were 12x12 inches. 
 
 Where the dam rested on rock at the ends, heavy shoes were used on the 
 piles and concrete deposited around their feet to make the work watertight. 
 The dam was completed in October, 1879, and remained thoroughly tight 
 until the dock was completed over seven years later. 
 
 The arch bridge at Topeka, Kansas, over the Kaw river, which is being 
 constructed on the Melan system, of concrete and steel, by Keepers and 
 Thacher, the designing engineers, is a most interesting piece of work. The 
 coffer-dams were required by the specifications to be watertight, and to 
 
 FIG. 56 TOPEKA BRIDGE COFFER-DAM NO. 4. "A" shows puddle to stop leak. 
 
 effect this 4x12 inch tongue and groove sheet piling was used. The size of 
 the coffer-dam for pier No. 4 was 18x55 feet in the clear (Fig. 56) and the 
 piling was driven about sixteen feet into the sand bottom or twenty-two feet 
 below low water. The driving was done by a 1,600-pound hammer with 
 thirty-six feet leads ; the power being furnished by a 15 H. P. hoisting 
 engine. 
 
 No puddle was used around the outside except to stop leaks, and the 
 dam was kept clear of water with a No. 6 Special Van Wie sand pump. 
 The capacity of the pump was 3,000 gallons per minute of water, and from 
 sixty to eighty yards of sand per hour. It; was operated with a 15 H. P. 
 
THE COFFER-DAM PROCESS FOR PIERS. 79 
 
 engine. The other piers were handled in a similar manner and with no par- 
 ticular trouble. 
 
 The growing scarcity of timber will doubless lead to the use of metal at 
 some time in the future, to replace sheet piling for coffer-dams, but where 
 timber is abundant and reasonable care is exercised in its use, it will con- 
 tinue to be of great service in obtaining foundations by this method. 
 
ARTICLE VII. 
 
 THE COFFER-DAM PROCESS FOR PIERS.* 
 
 METAI, CONSTRUCTION. 
 
 HIN steel shells have been used extensively for foundation work, but 
 in the majority of cases they have been retained as essential fea 
 tures of the permanent construction. 
 
 This is more particularly the case in locations where stone is 
 scarce or expensive and it becomes necessary to substitute some 
 other material for foundations. Tubular steel piers are con- 
 structed of two tubes, ranging from 24 inches to several feet in 
 diameter, or in the case of pivot piers, from 15 feet, with a single tube 
 for a pier, to 30 leet or more. 
 
 In a number of instances the steel shells for ordinary piers have 
 been made oblong, in the general form of a stone pier, and braced internally 
 to hold them in shape during sinking, after which they are filled with 
 concrete. 
 
 The metal shells for the Hawkesbury bridge in Australia were of this 
 character, 20 feet wide, 48 feet long and with rounded ends. Each one was 
 provided with three dredging wells, each 8 feet in diameter, through which 
 the dredges shown in the view (Fig. 57) were operated. While these piers 
 were not used as coffer-dams, they were made water-tight by boiler riveting, 
 so that by pumping water in and out the displacement could be kept con- 
 stant, and in this way control the pier in an average tide of five feet. These 
 piers were sunk, by dredging out the material from the inside, to the great 
 depth of from 135 feet 8 inches to 197 feet below the pier tops, or a distance 
 of 155 feet below low water. 
 
 Both inclined and vertical cutting edges were used, with the result that 
 
 * Metal caissons have been used much more frequently in this country than have metal 
 ' offer-dams, the reason being the cheapness of timber and its more easy application. 
 
 In England metal coffer-dams are more frequently used. The example given in this 
 article the Forth bridge coffer-dams might have been supplemented by reference to those 
 used on the Clarence bridge at Cardiff, the construction used being illustrated and described 
 in Engineering, and is especially notable for the design of the bracing. 
 
 80 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 81 
 
 the inclined ones were of frequent trouble and the vertical ones none what- 
 ever. 
 
 "If it is essential to increase the bearing surface at the bottom of the 
 caisson to an area which is not required in the upper portion, this end can 
 be secured by a vertical cutting shoe of considerable height, with a step or 
 steps into the smaller diameter. This is quite as efficient to secure the end 
 in view as a long incline on the cutting shoe, and has decided advantages. 
 In the denser material the vertical sides leave the ground undisturbed for 
 some height close to the skin of the caisson, and a vertical guide is secured 
 
 
 riG. 57. HAWKESBURY BRIDGE. Caisson No. 6 in Process of Sinking, Showing 
 Excavator and Shore Chains for Maintaining Vertical Position. 
 
 which is entirely wanting in the case of an inclined shoe. This guide is 
 valuable in cases where the soil may differ in density under the shoe, and 
 particularly so if the excavation has been carried too far below the bottom 
 of the shoe. With an inclined shoe and a slip of soil into the dredging 
 well from one side more than another, experience in deep dredging has 
 shown that there is a decidedly greater tendency to a horizontal movement 
 than with a vertical shoe. The former has a flare to direct this sidewise 
 motion in the first place, and nothing but a certain amount of disturbed 
 material above the shoe to resist this tendency." 
 
 The above account is from the Engineering News of January 5, 1889, 
 
82 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 the work having been done under the direction of J. F. Anderson, of the 
 firm of Anderson & Barr. The shells were filled with concrete up to low 
 water and masonry built from low water up to the top of the piers. 
 
 Such work may be made water-tight by riveting according to ordinary 
 boiler-maker rules, or if extra thick plates are used this can be exceeded 
 and the rivets spaced some farther apart. The joints may be made with 
 ordinary laps and calked, or a very much better appearance may be obtained 
 by the use of butt joints, and if desirable to avoid calking, then a calking 
 strip may be used to make the joints tight. This is merely a cloth or 
 canvas strip, thoroughly 
 saturated with paint paste, 
 and is laid between the 
 metal surfaces, and the 
 riveting draws the plates 
 upon it and a tight joint 
 will result. The shells will 
 be filled with concrete as 
 soon as the piers are in 
 place and the foundation 
 prepared, so that only a 
 temporary use is required 
 of the strip. 
 
 When metal cylinders 
 are used simply as casings 
 for concrete they need not 
 be made water-tight, as they 
 can be dredged out and 
 have the concrete deposited 
 through the water. The 
 metal should never be less 
 than one-quarter inch in 
 thickness, and on first-class 
 
 work five-sixteenths to one-half inch is preferable. Railroad work of this 
 character is usually constructed of three-eighths inch metal for ordinary 
 depths. 
 
 The pivot pier of the bridge over the Little Bras d'Or river in Cape 
 Breton was constructed of seven metal cylinders braced together. The cen- 
 ter tube was 4 feet in diameter, while the six outside cylinders were 3 feet 
 in diameter. (Fig. 58). The center pivot, about which the span revolves, 
 rests on the center tube, while the track is supported by the other tubes, 
 but resting directly on rolled beams covered with three-eighths inch plate. 
 
 The tubes rest on a clump of piles, cut off at the bed of the stream, with 
 
 FIG. 58. GROUP OF CYLINDERS FOR PIVOT PIERS. 
 
COFFER-DAM PROCESS FOR PIERS. 
 
 one pile extending up into the center of each tube about six feet, around 
 which the concrete was deposited, thus preventing displacement. Concrete 
 and stone were placed on the outside up to 15 feet, as a protection. 
 
 This work was described by Martin Murphy. in Trans. Am. Soc. C. E., 
 Vol. 29, who also describes a pier for the Victoria bridge, over Bear river, 
 constructed with two tubes, resting on piles cut off at the bed of the stream, 
 but having four piles inside each tube. (Fig. 59.) Around the outside are 
 timber, concrete and broken stone as a protection. The saw used for cut- 
 ting off the piles under the water was very much simpler than the one 
 shown in Fig. 35, and is illustrated in Fig. 60. 
 
 Cylinder piers on European work are often of very elaborate construc- 
 tion. The bridge on the Aa, at the crossing of the Russian Riga-Orel rail- 
 way, is supported on elegant cylinder piers, with 
 moulded caps, steel cut-waters, and are braced 
 together with cylinders transversly. (Fig. 61.) 
 This forms a very efficient construction, but so 
 expensive to manufacture that it is usually re- 
 placed by bracing of struts and rods, as in Fig. 
 59, or by a metal diaphragm (Fig. 62), stiffened 
 with angles. 
 
 Cylinders of water-tight construction and of 
 large diameter may be used as coffer-dams, where 
 they are sunk into impervious strata, or by 
 sealing them with concrete around the bottom 
 where they are placed upon smooth rock bottom. 
 In the construction of light-houses such cylinders 
 have been placed upon clean rock bottom through 
 from 12 feet to 18 feet of water and concrete 
 deposited around the circumference of the base 
 outside and inside to make them water-tight, 
 after which they were pumped out and the foun- 
 dation laid. 
 
 To withstand the pressure of any considerable depth of water the thick- 
 ness and strength should be calculated and the construction carefully 
 designed. Unless the depth of water exceeds ten feet, or the diameter of 
 tube exceeds six feet, the minimum thickness it is advisable to use, will be 
 sufficient for strength. 
 
 This refers only to quiescent pressure, and any shock must be carefully 
 considered and taken account of, by interior bracing if necessary. 
 
 The most thorough discussion of the strength of thin, hollow metal 
 cylinders is given in " Elasticitat and Festigkeit," by C. Bach. This con- 
 siders the cylinder to have sides of a greater thickness than is true with 
 
 FIG. 59. PIER OF TWO CYLIN- 
 DERS, VICTORIA BRIDGE. 
 
8 4 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 pier shells, and having one radius given, the radius to the other side of the 
 plate is found from the formula, the stress being variable from the inside to 
 the outside of the plate. 
 
 For thin cylinders the stress may, without appreciable error, be assumed 
 to be uniform over the cross section of the plate, and the thickness t in 
 inches be found from the formula 
 
 t .001 r h 
 where r is the radius of the cylinder in feet and h is the depth of the water 
 
 foundation Pi/ing for 
 Victoria. Bridge 
 
 JL 
 
 
 iflhl 
 
 i 
 
 nr 
 
 
 
 
 
 t 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 O 
 
 
 - 
 
 --16' 
 
 0-- 
 
 - 
 
 > 
 
 
 
 
 
 CwJ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2tf 
 
 j 
 
 , 
 
 
 
 
 
 
 
 
 
 Jd 
 
 V-,' 
 
 J6V/d. 
 
 L L 
 
 r n 
 j i 
 
 u L 
 
 -i= =r 
 1 
 1 
 U 
 
 n 
 i 
 
 UA 
 
 1 ' 
 1 | 
 J J 
 
 1 ! 
 
 i J 
 
 j, 
 
 r^ 
 
 L. 
 1 
 
 ^h 
 
 JjS-w^p 
 
 J ^ v 
 
 |r =- =r ====- =' = 
 
 FIG. 60. CIRCULAR SAW FOR CUTTING OFF PILES UNDER WATER. 
 
 to the section in feet, and t in no case to be used less than one-quarter incn 
 in thickness. 
 
 This is on the assumption that the metal will stand 5,000 pounds per 
 square inch in compression with safety. For large cylinders, or for rec- 
 tangular shells, girders and stiffeners or ties and struts must be added to 
 prevent distortion. 
 
 The foundations for the great Forth Bridge, which were constructed 
 
86 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 under the direction of Sir John Fowler and Sir Benjamin Baker, required 
 the use of various methods to reach solid bearing, as the enormous weight 
 to be carried required the most substantial piers obtainable. 
 
 The use of coffer-dams of metal for the Inchgarvie piers is described by 
 Engineering: The site of the two north or shallow piers being wholly sub- 
 merged at high water, and about half in the case of the northeast and three- 
 fourths in the case of the northwest pier, submerged also at low water, the 
 
 preliminary work was 
 tidal, and between spring 
 tides no work could be 
 carried on at all at this 
 place. When it is con- 
 sidered how exposed the 
 position was there the 
 work having to be car- 
 ried on upon a narrow 
 ledge of rock attacked 
 by wiiid and waves from 
 all sides it will be un- 
 derstood that the pro- 
 gress could not be very 
 rapid. The conditions 
 of the contract here re- 
 quired that the rock 
 should be excavated in 
 steps, and that the rub- 
 ble masonry comprising 
 the foundation of the cir- 
 cular granite piers (Fig. 63) should be bound by an iron belt 60 feet in 
 diameter and 3 feet deep; the highest portion of the rock upon which 
 this belt rested to be 2 feet below low water; the belt, or at any rate a part 
 of it, to be brought down to form a protection for the foundation rubble 
 masonry upon the lower steps. 
 
 It was therefore decided to cut a chase 8 feet wide (3 feet to the inside 
 and 5 feet to the outside of the 60 feet circle) out of the rock where it was 
 higher than 2 feet below low water, to make the 60 feet belt of three thick- 
 nesses of one-half inch plate and to carry the center plate downward, after 
 it had been cut, in such a manner as to fit as nearly as possible the natural 
 contour of the rock. (Fig. 64 A.) A light staging was, therefore, erected 
 above high water, the correct center of the pier placed upon it, and by 
 means of a trammel-rod 30 feet in length, from the end of which a pointed 
 sounding-rod was suspended, a correct reading was taken every 6 inches on 
 
 FIG. 62. CYLINDER PIERS, WITH DIAPHRAGM. 
 
OF THK 
 
 UNIVERSITY 
 
 87 
 
 COFFER-DAM PROCESS FOR 
 
 the circumference of the 60 feet circle, after a diver had been around to 
 clear out any loose stones lying in the line, or picking off any sharp points 
 projecting. These readings were plotted and the center plates cut to it. 
 In the meantime work had been done upon the chase; and, when nearly 
 cut down to the right level, the belt was put together on the staging exactly 
 above the site of the pier. The plates, projecting downward and forming 
 the shield, were stiffened by I bars vertically over the butts, and where 
 required to be carried down to a considerable depth, as in the case of the 
 northwest pier, they were further stiffened by horizontal circular girders 
 and stayed to the rock by bars of angle iron. The whole belt was now 
 riveted up, and when ready received two coats of red lead paint, and was 
 lowered down to position by means of hydraulic jacks. (Fig. 64B.) The 
 top edge of the 3 feet belt was then leveled all round, and corrected where 
 
 FIG. 63. CIRCULAR GRANITE PIER AS FOUNDED BY COFFER-DAM. FORTH BRIDGE. 
 
 necessary. A heavy angle iron 6 inches by 6 inches by J/Q inches ran 
 round the inside of the 3 feet belt, and upon this was now set a single tier 
 of temporary caisson, 10 feet in height, .and consisting of fourteen segments 
 of about 30 cwt. each in weight. This helped to keep the belt down to the 
 rock, and a number of heavy blocks of stone were placed on the top of the 
 caisson for the same purpose. A sluice door in the lower part was kept 
 open to admit of the tide flowing in and out. 
 
 Steps were now taken to make good the joint between the 3 feet belt and 
 the shield and the bed-rock. This was done in the following manner : A 
 number of concrete bags, about 14 inches by 30 inches, and 8 inches to 9 
 inches thick, were prepared and passed down to a diver, who laid them 
 round the outside of the belt at a distance of about 4 inches. A second 
 row was next laid round the outside of the first row, and tolerably close up, 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 the space between the two being made up by clay puddle well stamped 
 down. Any split or hole or crevice in the rock was also filled with clay. 
 Upon these two lower rows other bags were now laid crosswise ; upon these, 
 two rows lengthwise, and a fourth row crosswise on the top, which was 
 laid close up to the belt. This was done in sections of about 15 feet to 16 
 feet length all along the shield, but round the outside of the treble belt only 
 two bags deep were laid. On the inside also a single row of clay bags, 
 
 AI.IV. IROH 
 
 Section Through Shield 
 cS/miv/rvgMocte of Aiding Joint to RocK 
 
 Cone, bags loaded 
 ly/tA sane/ bags. 
 
 Cement groi/t. 
 
 w 
 
 I ROM COFFER-DAM . //. IV. PIER-* 
 Outside View o/c5/i/e/c/. 
 
 FIG. 64. FORTH BRIDGK. METAL COFFER-DAM. 
 
 backed by a row of concrete bags, and loaded with stones, was laid round 
 the complete circle. Cement grout, without intermixture of sand, was now 
 prepared and passed down to the diver but only at slack tide, high water 
 or low water who lifted off one or more of the top bags and poured the 
 grout into the narrow space left, until it overflowed. He then replaced the 
 bag and proceeded to the next division, until all was done. Forty-eight 
 hours were allowed to elapse for the setting of the cement ; the sluice valve 
 
THE COFFER-DAM PROCESS FOR PIERS. 89 
 
 was then closed and the caisson pumped out gradually. When leaks were 
 discovered the diver descended to examine the outside, and where neces- 
 sary, cut out some of the grouting and replace it by new. 
 
 As it was not considered that this cement joint would be able to stand 
 the full pressure of the tidal rise the coffer-dam was worked as a half tide 
 one, it having to be pumped out every tide as soon as the water had fallen 
 below the top edge of the temporary caisson. In addition to the hydro- 
 static water pressure, the caisson had to stand the heavy seas thrown 
 against it, whether coming from east or west. Under these circumstances 
 it was often considered advisable not to pump out the coffer-dam, but leave 
 the sluices open and allow the tidal flow free access. Under such condi- 
 tions it will be easy to see that, during a season of bad weather, much delay 
 could not be avoided, and though the work of excavation had been com- 
 menced in the summer of 1883 it was not till the middle of April of the 
 following year that the first 'rubble masonry could be laid in this pier. In 
 working the excavation no blasting was done within one and a half feet of 
 the iron belt, but the rock was quarried up to within 6 inches and the rub- 
 ble then built in at once. Any steps cut in the deeper portion were invar- 
 iably at least twice as broad as they were deep. The deepest point to 
 which the excavation had to be carried in this pier was 8 feet below low 
 water. 
 
 The coffer-dam or caisson for the northwest pier, Inchgarvie, was done 
 in the same way precisely as described for the northeast, only that owing 
 to the experience gained by the divers and other men engaged upon the 
 work the progress was much more rapid. 
 
 In the northwest pier the depth of the shield was 15 feet below low 
 water, and extended to nearly one-half of the circumference. There was, 
 therefore, in addition to the vertical I bars which covered the butt joints 
 of the shield plates, three horizontal circular girders, carried at a distance 
 of 4 feet 6 inches from each other, and from these a number of horizontal 
 tie bars with cross-bars at the ends were carried radially and level to the 
 rock opposite and pinned to it, and afterward built into the solid rubble 
 masonry. (Fig. 64B.) 
 
 This mode of making the joint between the rock and the iron belt was 
 simple and quite effective. Most of the leaks were due to natural crevices 
 in the rock, running from the inside to the outside at a considerable depth. 
 These were circumvented by building small clay dams round, and leading 
 the water by a chute to the pump. Leaks were also caused by the action 
 of heavy waves running up to the temporary caisson at low water with 
 great violence, and shaking the whole fabric. 
 
 The whole of the northeast pier was built in a half-tide caisson, as the 
 work was not pressing ; but in the case of the northwest pier, so soon as the 
 
9 o 
 
 THE COFFER-DAM PROCESS FOR iIERS. 
 
 rubble masonry inside had been brought up to low water level a second tier 
 of temporary caisson was added, and the work could then be carried on at 
 all states of the tide. While tidal work was carried on in these two coffer- 
 dams the amount of water which had to be pumped out every tide was 
 250,000 gallons in the one case and 340,000 in the other. The time occu- 
 pied was 50 to 55 minutes, but work was, of course, commenced so soon as 
 the higher parts were laid dry. For pumping out smaller quantities of 
 water collected through leaks, pulsometers or small centrifugal pumps 
 were used. 
 
 An exterior view of the work is shown in Fig. 65, and while the method 
 
 FIG. 65. FORTH BRIDGE, CIRCULAR GRANITE PIER AND METAI, COFFER-DAM. 
 
 was successful and worthy of much study, the expense would only be 
 justifiable where the metal would be retained as part of the permanent 
 foundation, which was the case on this work. 
 
 In man} 7 cases such a shell could be designed of the proper size for the 
 footing course, and after use as a coffer-dam in obtaining the foundation it 
 could be filled with concrete and serve as a base for the pier. Being made 
 in sections vertically, portions projecting above low water could be removed 
 and used on still other piers. 
 
 Metal sheet piles are seldom used for any class of work, and need not be 
 
THE COFFER-DAM PROCESS FOR PIERS, 91 
 
 discussed at length in this connection. On some harbor work at Cuxhaven 
 Harbor, Germany, hollow metal sheet piles, of elongated elliptical section, 
 were used, and after being driven were filled with concrete. 
 
 Whatever the class and form of material it may be decided to use, in 
 securing a foundation bythe coffer-dam method, the temporary construction 
 should be so related to the permanent foundation that as much as possible 
 of the material used and labor employed will be of service in the finished 
 structure. 
 
ARTICLE VIII. 
 
 THE COFFER-DAM PROCESS FOR PIERS.* 
 
 PUMPING AND DREDGING. 
 
 HE degree of success which has been attained in the building of a 
 
 coffer-dam will be evident when the pumping process is begun. After 
 having been pumped out, if the leakage is so small as to require only a small 
 amount of pumping to keep it free from water, it may reasonably be consid- 
 ered a success. 
 
 The pumping should not exceed what can be done by a steam siphon, a 
 small pulsometer, or by running a centrifugal pump intermittently. Should 
 leaks develop which cannot readily be contended with, then repairs must be 
 made. 
 
 The use of pumps for this class of work on ancient bridges is described 
 by Cresy. The bascule, used by Perronet at the bridge of Orleans (Fig. 66), 
 is one of the most primitive forms. It consists of a see-saw apparatus, at each 
 end of which ten men were placed, and 150 motions were given it in each quar- 
 ter of an hour. Four cubic feet of water were raised three feet each time, or 
 about 300 gallons per minute. Various other kinds of pumps were used at 
 this bridge, among them the chapelet, which is similar to a modern chain 
 pump, worked by hand. Then the same device was employed, but geared 
 to be operated by horses on a platform. A chapelet operated by a water 
 wheel was also used (Figs. 67 and 68). The large wheel had 124 cogs, 
 while the pinion had 15, which caused the raising of over sixty-six buckets 
 on the chain for each turn of the large wheel. At 180 turns of the wheel 
 per hour, with each bucket lifting 290 cubic inches of water, the capacity 
 was about 250 gallons per minute. 
 
 A great bucket wheel was employed by the same engineer at the Neuilly 
 bridge, 16 feet 6 inches in diameter, 4 feet 6 inches wide, with sixteen 
 buckets. 
 
 * Attention is called to the numerous references in other articles of the pumping plants 
 actually employed on coffer-dams, and especially to the plant used at Topeka, page 78. 
 
 Great care should always be given to the selection of a pumping plant of the proper type 
 and proper size, as the statements regarding capacity are often misleading. The outfit 
 should be, if needed, one able to take care of the dredging, if the material is such that it can 
 be pumped. 
 
 92 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 93 
 
 FIG. 66. OI<D BASCUIvE PUMP. 
 
 The pumps used at the present time on very small work are usually 
 square wooden box lift pumps, such as are used on large river barges, and 
 are worked by one or more men lifting on a plunger. These are' often 
 replaced by a similar pump of metal (Figs. 69 and 70) with a tube of gal- 
 vanized metal, and often spiral riveted. 
 The one shown in Fig. 69 has the top 
 and bottom soldered to the tube, while 
 the one in Fig. 70 has screw joints. The 
 cost of a 4-inch pump eight feet long 
 with fixed top and bottom would be about 
 $6, while the screw joints would about 
 double the cost. 
 
 Such pumps are, however, little used, 
 as the labor becomes excessive where 
 there is any quantity of water to deal 
 with, and diaphragm pumps (Fig. 71) 
 are employed, which work on a rubber 
 diaphragm, in place of a piston and 
 plunger, and throw a large amount of 
 water, besides allowing the passage of 
 
 sand and gravel without choking the pump. The 2 Y?. -inch suction has 
 a capacity of twenty-five gallons per minute, and the 3-inch suction 
 of fifty-eight gallons per minute, the list price of the two sizes being $20 and 
 $26, respectively; the maximum lift of the pump being thirty feet. 
 
 Where steam can be obtained steam siphons are often used, the steam 
 being introduced into the main pipe through a nozzle, thus causing a suction, 
 which with a 3-inch discharge Van Duzen jet will deliver 7,200 gallons of 
 water per hour, the height of the pump above water being 11 feet, the point 
 of discharge being 19 feet above the pump, making a total lift of 30 feet. 
 This size will require an 18-horse power boiler and a steam pressure of fifty 
 pounds. The suction pipe is one inch larger than the discharge, while the 
 steam pipe is 1# inches in diameter, with a jet opening of about |f inches. 
 The list price of a pump of this size (Fig. 72) is $36, the piping being 
 extra. The pump is constructed of gun metal and will last indefinitely. 
 The strainer should always be used and will cost about $4 extra for the 
 4-inch pipe. The piping should have long bends in place of elbows where 
 a turn is required. 
 
 This make of pump is manufactured from ^-inch discharge, with a 
 capacity of 200 gallons per hour, up to 5-inch discharge with a capacity of 
 12,000 gallons per hour. The smaller sizes are useful for priming centrif- 
 ugal pumps and for a variety of uses around a contractor's plant. 
 
 The Lansdell siphon pump (Fig. 73) has a double suction C C, to which 
 
94 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 rubber suction pipes are attached. The steam pipe is attached to B, and 
 when the steam is turned on it is blown across A and through D, thus ex- 
 hausting the air from the chamber A. Water rises through C C by atmos- 
 pheric pressure to fill the vacuum, and it is forced out through D by the 
 steam, the velocity being proportional to the steam pressure. The steam 
 
 FIG. 67. OLD CHAPELET, SIDE ELEVATION. 
 
 supply should be as close to the pump as possible, to prevent condensation, 
 and the turns in the pipe should be easy bends, as stated regarding the Van 
 Duzen jet. When the height exceeds fourteen feet, to which the water is to 
 be pumped, the suction pipes must be long enough to allow the center of 
 the pump to be placed fourteen feet above the water. With a 3-inch dis- 
 charge, a \y z -inch steam pipe is required and a 12-horse power boiler. With 
 a 6-inch discharge a 2^ -inch steam pipe is required and a 50-horse power 
 boiler. 
 
 The rated capacity of the 3-inch is 450 gallons per minute, of the 6-inch 
 1,800 gallons. But this would likely not be realized in practice. 
 
 The vacuum pump which has reached the most general adoption is the 
 Pulsometer, and is in 
 many ways better adapt- 
 ed to light service than 
 a centrifugal pump of 
 small size. There are 
 no bearings to keep up, 
 no belts to keep tight, 
 and no trouble in pre- 
 paring a foundation, as FIG. 68. OLD CHAPBLET, END ELEVATION. 
 the pump is suspended 
 
 by the hook shown in Fig. 74. The pump is operated by admitting 
 tht steam through the pipe at the extreme top (Fig. 75), the pump having 
 been previously primed by filling the middle chamber with water. The air 
 valves are closed and the steam passes into the right hand chamber A 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 95 
 
 FIG. 69. HAND 
 
 PUMP. 
 SOLDERED JOINTS. 
 
 FIG. 70. HAND 
 
 PUMP. 
 SCREW JOINTS. 
 
 clearing it of water by forcing it into the 
 discharge chamber shown in dotted lines. 
 The steam then condenses at once and 
 the ball C changes its seat, closing the 
 right hand and opening the lett hand 
 chamber to the steam. The vacuum, 
 formed by the bteatn condensing in the 
 right hand chamber A, allows it to fill 
 with water by atmospheric pressure 
 through the suction pipe at the extreme 
 bottom and through the chamber D, it 
 being retained by the valves E E. The 
 steam then enters the left hand cham- 
 ber A and the operation is repeated. 
 The chamber J is a vacuum chamber. 
 
 In starting the pump the steam is 
 turned on for three or four seconds, then 
 shut off for four or five seconds, alternat- 
 ing these movements until the pump is 
 started. The steam is then turned on 
 
 about half or three-quarters of a revolution, the two side air valves opened 
 
 about half a turn, and then the middle air valve opened slowly until a 
 
 regular stroke is obtained. 
 
 The capacity of the 3-inch dis- 
 charge, with a 3^ -inch steam pipe and 
 
 operated by a 9-horse power boiler, is 
 
 180 gallons per minute when the lift 
 
 is as much as twenty- five feet; and 
 
 for the 6-inch discharge, with a 1^- 
 
 inch steam pipe and operated by a 
 
 35-horse power boiler, 1,000 gallons 
 
 for the same lift. 
 
 The pulsometer is remarkably 
 
 smooth in operation, and except for 
 
 the slight click of the ball and the 
 
 discharge of water in a steady stream, 
 
 one would scarcely know it was pump- 
 ing. Where a good-sized hoisting 
 
 engine boiler is in use on foundation 
 
 work, it can be used to supply the 
 
 steam for pumping. The work illus- 
 
 trtaed in Fig. 4 was easily kept free of water by a small pulsometer. 
 
 FIG. 71. DIAPHRAGM PUMP. 
 
9 6 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 while its use has been cited in a number of cases where the coffer- 
 dam was pumped out by a centrifugal pump, and then the leak- 
 age kept under control by a medium sized pulsometer, which required but 
 little attention. The pump should be provided with a strainer at the bottom 
 of the suction pipe, all the connections must be air tight, no sharp bends 
 should be made in the pipe, and with dry steam successful working will 
 result. Another pump of similar construction is the Maslin Automatic 
 Vacuum Pump, which differs from it in important details. What has been 
 said regarding the pulsometer will apply as well to the Maslin pump. 
 
 All the foregoing devices are for use where the amount of water to be 
 handled in a given time is of limited amount, but 
 where large quantities are to be pumped out of coffer- 
 dams in short periods of time, resource must be had 
 to centrifugal pumps, which have reached a high 
 state of perfection. Where the water is to be lifted 
 ten feet an ordinary 
 ( reciprocating pump 
 would exhibit an 
 efficiency of only 
 30 per cent, while 
 a centrifugal pump 
 would have an effi- 
 ciency of 64 per 
 cent. For a lift of 
 seventeen feet the 
 reciprocating type 
 would have an effi- 
 ciency of 50 per 
 cent, while the 
 centrifugal would 1 
 reach its maximum 
 of 69 per cent effi- 
 ciency, dropping to 
 only 50 per cent for 
 a lift of fifty feet, while the other type would increase to 75 per cent. 
 From this it will be seen that the centrifugal pump is essentially a low lift 
 machine. 
 
 Actual tests of pumps show that the maximum results are very seldom 
 realized, a 9-inch discharge of one make showing an increase from 46.52 per 
 cent for a 12.25 feet lift, to 57.57 per cent for a 13.08 lift; while another 
 make of 10-inch discharge, shows a decrease from 64.5 per cent for a 12.33 
 lift, to 55.72 per cent, for a 13 feet lift. The greatest efficiency at hand is 
 
 FIG. 72. VAN DUZEN 
 JET PUMP. 
 
 FIG. 73. I.ANSDEXI/S 
 SYPHON PUMP. 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 97 
 
 shown by a German pump with a 9^- 
 inch discharge, a 10.3-inch suction, and 
 a 20.5-inch disk, running at 500 revolu- 
 tions. The lift was 16.46 feet and the 
 efficiency 73.1 per cent! 
 
 That such results are not realized on 
 actual work is readily understood when 
 it is considered what little care is used 
 to properly place and operate such a 
 plant, how little attention is paid to 
 having a proper boiler and engine, and 
 what lack of care there often is to keep 
 the plant in good repair. 
 
 An ideal outfit for operating by steam 
 is shown in Fig. 76, where the engine 
 is directly connected to a Heald & Sisco 
 pump. All the trouble and vexation 
 
 FIG. 74. PULSOMETER STEAM PUMP. 
 
 from the use of a belt being done away 
 with, and no loss of power through slip- 
 ping of belts. The machine can be 
 placed on the barge which carries the 
 boiler, the suction pipe being run hori- 
 zontally across as in Fig. 56, while a 
 short discharge pipe discharges directly 
 into the river. Where electric power 
 plants are available a still better arrange- 
 ment will be to have an electric motor 
 directly connected to the pump, and all 
 the trouble incident to the use of a boiler 
 on the work will be avoided. 
 
 K 
 
 FIG. 75. SECTION OF PULSOMETER. 
 
9 8 
 
 fHE COFFER-DAM PROCESS FOR PIERS. 
 
 Electric power can also be used for hoisting and for pile driving. 
 Examples of the use of motors on hoisting machinery will be given in a later 
 article. 
 
 The suction should always be fitted with a section of smooth-bore rubber 
 hose (Fig. 77A) to give it flexibility, a length of about eight feet being 
 usually sufficient. The best hose is made with a spiral metal core which 
 adds to its strength and durability. 
 
 The suction pipe is ordinarily made of sections of wrought iron pipe, 
 
 FIG. 76. CENTRIFUGAL PUMP, DIRECTLY CONNECTED TO ENGINE. 
 
 with screw connections, but as this is troublesome to change sections, it will 
 be found advantageous to use the spiral riveted pipe with flange couplings 
 (Fig. 77B), and to have extra sections from two to six feet long, with several 
 sections of each shorter length, so the length of the suction pipe can be 
 readily changed to suit the depth of the excavation. The flanges must be 
 provided with rubber gaskets to keep the pipe air tight. 
 
 The strainer (Fig. 77C) is used to prevent large stones, sticks or obstruc- 
 tions from entering and clogging ordinary pumps, and usually comprises a 
 foot valve to retain a pipe full of water and make the priming easy. The 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 99 
 
 strainer or end of the suction pipe is usually placed in the lowest point, and 
 sometimes a box or sump is provided, as a well into which the water is 
 drained from the other and higher portions of the work. A small set of 
 falls should be attached to the foot to raise the pipe and clean out the strainer 
 when necessary. 
 
 The centrifugal pump itself must be in first-class repair to do economical 
 work, and should be a large enough size so that it need not be run beyond 
 its economical capacity. The style of pump to use will depend upon the 
 work to be done, but for coffer-dam work a vertical pump could not be used 
 easily and need not be considered. Where practically clean water is to be 
 pumped an ordinary style of pump should be used, but where much mud or 
 sand will be drawn up a sand pump is best ; and where a large part of the 
 excavation is to be done with the pump, as at Topeka, a dredging pump 
 will be the proper type. 
 
 FIG. 77. SUCTION DETAIL FOR PUMP. 
 
 The pumping required on the Chattanooga work, 5,000 gallons per min- 
 ute to a height of about fifteen feet, would have been done most econom- 
 ically by a 15-inch pump, with a 40-horse power engine and a 50-horse 
 power boiler. But a pump of this size would not find ready use in a con- 
 tractor's work, and for this reason two 8-inch pumps would have been the 
 better outfit to purchase, unless the work was very extensive ; and each 
 pump should be provided with a 25 or 30-horse power engine, so as to run 
 the pumps somewhat beyond the economical capacity, which could readily 
 be done with a direct connected engine, where there would be no belt to slip. 
 
 The work required on the Forth bridge coffer-dams could also be done 
 by the 15-inch pump above described, the lift being about 3 feet at the start 
 
IOO 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 FIG. 78. CENTRIFUGAL PUMP, DOUBLE SUCTION. 
 
 and reaching 18 feet as the dam was cleared, the 340,000 gallons being 
 
 pumped out in about one hour. 
 
 Centrifugal pumps are rarely required for a lift of over 20 feet on this 
 
 class of work, which is only slightly beyond the economical lift, and the 
 
 height should never exceed 
 30 feet, which would require 
 for the 15-inch pump an en- 
 gine of 75-horse power. 
 
 The pump may be located 
 on the coffer-dam, but in case 
 of high water during the pro- 
 gress of the work the outfit 
 may be damaged and it is best 
 to place the pump on a boat, 
 as in Fig. 56, with a section of 
 horizontal suction pipe across 
 
 to the work, which should be as short as possible. 
 
 The ordinary type of pump (Fig. 76) may be fitted with a primer, con- 
 sisting of a small hand force pump attached to one side of the pump, for 
 
 filling the pump 
 
 and suction pipe. 
 
 A more simple way 
 
 is to provide a bar- 
 rel above the pump, 
 
 which can be kept 
 
 full by using a 
 
 small steam jet, and 
 
 by means of a pipe 
 
 with valve from 
 
 the bottom of the 
 
 barrel to the top of 
 
 pump, the contents 
 
 can be emptied into 
 
 the pump to prime 
 
 it. Priming may 
 
 also be easily ac- 
 complished by in- 
 serting a hose into 
 
 the discharge pipe 
 
 and filling the pump directly with a steam jet. 
 
 Double suction pumps (Fig. 78) allow the water to enter on each side of 
 
 the piston, and thus a perfect balance is secured, which does away with all 
 
 FIG. 79. DREDGING PUMP. 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 IOI 
 
 end thrust on the bearings. This pump is most easily primed by using an 
 ejector, or a flap valve such as is shown on the discharge pipe of the dredg- 
 ing pump (Fig. 79) and which serves to 
 retain the water in the pump. Where a long 
 discharge pipe is to be used, a quick closing 
 gate valve may be introduced into the pipe 
 near the pump. 
 
 Where the material to be dredged out at 
 the foundation site is mud or sand or partly 
 gravel, it can be removed during the process 
 of pumping by using a dredging pump. In 
 case there were 700 yards of material to be 
 removed and an 8-inch pump was provided, 
 it would not be advisable to count on more 
 than 10 per cent, of solid matter being dis- 
 charged by the pump, as the suction could not 
 be kept working close up to the sand or mud. 
 By using a 30-horse power engine, a discharge 
 of 2,000 gallons per minute would be reached, 
 or with 10 per cent of loose solid matter, the 
 excavation would be made in less than two 
 working days. 
 
 The piston of a dredging pump (Fig. 80) 
 is provided with large openings to receive the material, and the one illus- 
 trated is provided with side plates so that all wear is taken off the pump 
 casing. 
 
 One of the most remarkable pieces of work done with this class of pumps 
 was the use of Edwards' Cataract pumps in dredging the ship channel in New 
 York harbor. This is described in the Trans. Am. Soc. C. E., Vol. 25. 
 The work was done by three dredges, which were much the same as small 
 sea-going vessels, the largest being the Reliance, 157 feet long, and carrying 
 650 cubic yards of dredged material. Two separate pumps were provided, 
 each with 18-inch suction pipes, reaching from the sides of the vessel and 
 parallel to it down to the bottom to be dredged, being supported by suitable 
 hoisting tackle. These boats were kept under headway toward the dump- 
 ing ground while the dredging was in progress. The average load during 
 about a month's working of the Reliance was 585 cubic yards and the aver- 
 age time of loading about 48 minutes, while the average number of loads 
 per day was 6.73. 
 
 These dredges removed the enormous quantity of 4,299,858 cubic yards 
 of material at an average price of 24.48 cents per yard, the lowest price being 
 about 17 cents, the average price paid for other forms of dredging being 
 
 FIG. 80. DREDGING PUMP 
 PISTON. 
 
102 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 40.53 cents. On foundation work the amounts to be removed would be 
 small and the cost for this reason much higher, yet owing to the smaller 
 cost of the plant that would be required, the cost need not be greatly in 
 excess of the above. It is usual, however, as the amount to be dredged will 
 cost such a small proportion of the total cost of the substructure, to figure 
 from $1 to $2 per yard for excavation in ordinary coffer-dams. 
 
 Reference has already been made to hand dredging and a very cheap and 
 effective scraper was illustrated in Fig. 8. Where dredging is to be done in 
 tubes, wells or puddle chambers, it can be done by a clam-shell dredge or 
 grapple such as was shown in Fig. 57, in use on the Hawkesbury founda- 
 tions. 
 
 The Lancaster dredge (Fig. 81) is a well known form of this type of 
 
 FIG. 81. LANCASTER GRAPPLE. 
 
 machine, and can be operated from an ordinary derrick which is served by 
 a double-drum hoisting engine. This dredge will work best of course where 
 there is some depth of soft material to be removed. While a large dredge 
 would generally be hired by a contractor, these buckets can be owned by 
 him and the work carried on cheaply and conveniently. 
 
 Sand diggers such as were mentioned in Article II can often be hired 
 where other means are not at hand, or they can be rigged up very cheaply 
 if necessary. A very simple one (Fig. 82) can be built on an ordinary 
 barge, the engine being an ordinary one with a vertical boiler, while the 
 buckets are mounted in a very simple manner and operated through a well 
 in the center of the boat. Such a dredge will dig about 100 yards of sand 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 103 
 
 per day, with only two men to attend it, and will use less than one-half ton 
 of cheap coal, the total cost per yard thus running below five cents. Large 
 elevator dredges of this type are very elaborate affairs, and as they are in 
 wide use they can often be hired for making excavations. 
 
 The best known form of dredge, perhaps, is the dipper dredge. The 
 Osgood machines (Figs. 83 and 84) in use on the New York State canals are 
 among the best machines of this kind in use. Such dredges are more simple 
 in construction than elevator machines, and are consequently easier and 
 
 cheaper to keep in 
 repair. The hull 
 is 70 x 17 x 6 feet 
 with two 6 -feet pon- 
 toons which are re- 
 moved when going 
 through locks. 
 The engines consist 
 of a double drum 
 main engine with 
 8x10 inch cylin- 
 ders, a swinging 
 engine with 6x8 
 inch cylinders, and 
 a crowding engine, 
 5x6 inch cylinders, 
 which are all used 
 in operating the 
 digger of 1^ yards 
 capacity on a steel 
 boom 45 feet in 
 length. 
 
 The crowding 
 engine is used to 
 
 control the dipper and enables it to make a practically level bottom at one 
 cut, and also thrusts the dipper far enough beyond the boom to allow it to 
 dump fifty-two feet from the center. This dredge, which cost complete 
 $10,000, is operated by a crew of only four men and consumes but one ton 
 of coal per day of twelve hours, the average excavation during four months' 
 work being 549 cubic yards per day. The machine has sufficient power to 
 dig hardpan, boulders, and very soft shale rock. 
 
 A dredge of this make, of 3^1 yards capacity, working in mud and sand, 
 has dug material at the very low actual cost of .99 of one cent ! This of 
 course was an exceptional case, and the cost will rarely fall below five 
 
 FIG. 82. SAKD DIGGER. 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 105 
 
 cents per yard on easy work at a depth not exceeding ten feet, and in such 
 small amounts as would have to be dredged on coffer-dam work and in 
 about twenty feet of water the actual cost would likely reach fifteen cents 
 per yard. In case the dredge should be hired to do the work, a charge 
 of from twenty to thirty cents per yard would not be excessive depending 
 of course on the class of material and the amount. 
 
ARTICLE IX. 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 THE FOUNDATION. 
 
 HE coffer-dam is only the means of reaching a desired end, and this must 
 be borne in mind and the construction made as simply as possible to 
 obtain a first-class foundation. 
 
 When the coffer-dam is completed and pumped out work can then 
 proceed if the pumps are able to control the water easily. The charac- 
 ter of the foundation having been previously decided upon, after a careful 
 examination of the site, it is assumed that the temporary work has been 
 executed in a manner which is properly related to the permanent structure. 
 
 The different kinds of bottom likely to be encountered are : First, light 
 sand and gravel or mud of unknown depth; second, similar material over- 
 lying either cemented gravel, clay, hardpan or rock; third, a clean rock 
 bottom, which is approximately smooth and level; fourth, a sloping rock 
 bottom, which is either smooth or rough, and fifth, a rough and irregular 
 rock bottom. 
 
 Should the bottom be of the first kind light sand and gravel or mud of 
 unknown depth the soft upper layer may have been removed by a dredge 
 previous to the building of the dam, or it may be removed by a dredge or 
 grapple from within the inclosed area, and without the necessity of keeping 
 the dam pumped out, or pumping may be kept up with a dredging pump 
 and the light material removed in this way, after which the heavier material 
 may be removed as deep as necessary by hand shoveling and a dirt box, as 
 shown in Fig. 56. In such a bottom the foundation is usually made by 
 driving piles from two to four feet centers, this distance being regulated by 
 the bearingpower, as determined from Wellington's formula in Article IV, 
 and building upon the tops of the piles, after they have been cut off to a level 
 below low water, a grillage of timber. The space between the piles should 
 be filled with broken stone or concrete, and the grillage placed entirely below 
 low water, the coffer-dam being kept pumped out to allow this work to be 
 done, and also during the laying of the footing courses of the masonry 
 which are below the water. 
 
 When the soft bottom overlays good clay, hardpan or rock, as in the 
 second case, and the depth exceeds 20 or 25 feet below the water surface, 
 piles may be driven to the harder substratum and act as bearing piles. But 
 when the depth is in the region of 20 feet or less, it is best to excavate and 
 
 1 06 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 ID/ 
 
 place the foundation masonry directly upon the solid bottom. The founda- 
 tion will be of the character described for some of the following cases: 
 
 The third class is similar to the foundation at Chattanooga after the 
 gravel was removed. The fissures in the rock are 
 filled up or closed with cement and concrete, and a 
 leveling course of concrete put down on which to found 
 the pier. (Fig. 49). 
 
 Bottoms of the fourth class should have all the 
 loose and decomposed rock removed and steps cut out 
 by blasting and wedging, to give a secure hold for the 
 foundation, but if it is simply rough and irregular a 
 leveling course of concrete will be all that is required 
 on which to start the pier. Bottoms of clay and hard- 
 pan will require a very similar treatment, except that 
 the leveling course of concrete must be made of suffi- 
 cient thickness to properly distribute the pressure, 
 which will seldom be less than three feet and can often 
 be increased with advantage to six or eight feet. An 
 example of the stepping of rock bottom was given in 
 the account of the Forth Bridge piers in Article VII 
 and was shown by the dotted lines in Fig. 64. 
 
 Where there is a current caused by leakage through 
 the sides of a coffer-dam, or from the bottom, or if the 
 water within the dam is agitated by the pumping, it 
 will be best, after the bottom is clean and properly 
 prepared, to allow the water to run in and then de- 
 posit the concrete through the still water. This has 
 been successfully accomplished through 25 or 30 feet 
 of water, and while some engineers recommend allow- 
 ing the concrete to set from one to three hours before 
 depositing, to prevent the cement from washing out of 
 the concrete, this is not necessary nor advisable if the 
 proper care is exercised and the prcfper apparatus used. 
 The concrete should be made from one-third to one- 
 half richer than would be used for similar open air 
 work, as there will be some loss of strength. 
 
 The simplest method is to deposit the concrete in 
 paper sacks by sliding them down a smooth wooden 
 or iron chute, or by loading them into a box or skip 
 
 and dumping them out after the box reaches the bottom. The sacks 
 should be of tough paper, similar to flour sacks, and when they reach the 
 bottom they may be broken by a pike pole and the concrete allowed to run 
 
 FIG. 85. METAL TUBE 
 FOR CONCRETING. 
 
io8 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 together. Thin cloth sacks are sometimes used and they become fairly well 
 cemented together by the mortar which oozes through. 
 
 IT 
 
 o 
 
 
 o 
 
 fo 
 
 o : . 
 
 o 
 
 . 
 
 
 
 
 
 o : 
 
 o 
 
 
 o 
 
 o 
 
 o I: 
 
 
 
 
 o 
 
 
 
 o i 
 
 
 
 
 Q 
 
 o 
 
 
 
 -J I 
 
 
 ==3^-r= 
 
 FIG. 86. METAI, BUCKET FOR CONCRETING. 
 
 Where the amount of concrete is considerable it will be best to use a tube 
 or bottom dumping box. For placing concrete under water on the Bouci- 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 109 
 
 caii It bridge over the river Saone in France a wooden tube 16 inches square 
 was used. This is described in the Engineering News of May 18, 1893. 
 The tube was carried transversely across the caisson on a traveling crane 
 which ran lengthwise of the caisson on tracks on the sides, thus allowing 
 the tube to be moved in any desired direction. The tube was built in sec- 
 tions which could be easily removed, was provided with a hopper at the top 
 into which the concrete was dumped, and a drop door at the bottom to Jet 
 
 PL; AN 
 
 FIG. 87. CONCRETE PIERS. RED RIVER BRIDGE. 
 
 out the concrete. The tube was filled as it was lowered down into the 
 water, and opened when within 16 inches of the bottom. As concrete was 
 dumped in above, the tube was moved about and a 16- inch layer of concrete 
 deposited. When one layer was complete, another of the same thickness was 
 deposited. This method of using 16-inch layers was said to have obviated 
 laitance or the exuding of the gelatinous fluid which prevents uniform 
 
I IO 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 setting. The concrete was deposited about the heads of the piles and no 
 grillage used. The thickness of the concrete, which was deposited at the 
 rate of from 90 to 100 yards per day, was 9.84 feet, and was allowed to set 
 fourteen days before the pier was begun. 
 
 A metal tube may be used, such as was employed on the Harvard bridge 
 at Boston by W. H. Ward. This tube (Fig. 85) was not provided with a 
 bottom and the first filling of the tube was consequently done after the tube 
 was lowered and the concrete became somewhat washed. This may easily 
 
 be prevented by using con- 
 crete in paper sacks to fill 
 the tube the first time. 
 The tube was suspended 
 from a derrick and was 
 moved about so as to keep 
 the concrete level and de- 
 posit it in layers. This ac- 
 count is taken from Vol. 
 31 of the Engineering 
 News, from which is taken 
 the following description 
 of a metal bucket used by 
 W. D. Taylor on the Coosa 
 river. 
 
 This bucket (Fig. 86) 
 was of riveted construc- 
 tion and held one yard of 
 concrete. The maximum 
 depth of water was 26 feet, 
 at which depth the bucket 
 and its load became so 
 lightened that the bucket 
 tripped as soon as the 
 flanges touched the bot- 
 tom. Similar boxes are 
 often constructed of wood, 
 
 or they are often made "V"-shaped, one side being arranged to open and 
 dump the load. 
 
 For concrete work of this character natural cement is often used, but on 
 all important work Portland cement should be employed. The proportions 
 range from 1 of cement, 2 of sand and 4 of broken stone, to 1 of cement, 3 of 
 sand and 6 of broken stone. 
 
 On such a base either a masonry or monolithic concrete pier may be 
 
 FIG. 88. CONCRETE FORMS. RED RIVER BRIDGE. 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 Ill 
 
 constructed. The pier at Little Rock (Fig. 52) was of this construction and 
 of the composition given in Article VI. A similar piece of work was con- 
 structed on the Red River bridge on the St. Louis & San Francisco Railway 
 and is described in the Engineering News of June 2, 1888, by C. D. Purdon, 
 assistant engineer in charge of the work, under James Dun, Chief Engineer, 
 The cribs were filled with Louisville cement concrete up to within two feet 
 of low water, on which was built the pier. (Figs. 87 and 88.) 
 
 ''After the crib had been filled with concrete and the surface leveled off, 
 the center lines of the pier were located and a frame of 2"x8" plank the 
 shape of the pier, and four inches larger to allow for lagging, was placed in 
 exact position and held by pieces spiked to the crib. On this frame upright 
 posts 6"x6" and 5' 10" high, with a batter of one-half inch per three feet 
 were set in the position shown on the drawing, then the feet spiked to the 
 frame and another frame similar to the first, but six inches narrower placed 
 on them. This again was brought to exact position and braced to the crib 
 
 G./23 
 
 FIG. 89. CONCRETE FORMS. ILLINOIS AND MICHIGAN CANAI,. 
 
 and the frame completed by putting lagging of 2-inch plank inside the posts 
 and spiking to them. This lagging was horizontal in the body of the pier 
 and vertical (2"x4") at the ends, beveled pieces being introduced in the 
 ends at intervals to make up the difference of the upper and lower circles. 
 Next 2"x6" planks were placed across on the top of the posts, running clear 
 through the pier, to act as braces. In the rest of the frames these braces 
 were allowed to extend about six feet on each side and the frame braced by 
 spiking plank to them and to the vertical posts. After a section of frames 
 was completed a bed of cement mortar about two inches thick was spread all 
 over the concrete in the crib. On this the rough stone, in such pieces as one 
 man could easily handle, was placed so that no two pieces would be closer 
 than two inches, nor any piece within two inches of the frame, the stone 
 being thoroughly wet before laying. 
 
 "Next, on this course of stone another bed of mortar was placed, sufficient 
 to fill all the spaces between the stones and remain about two inches thick 
 above them. It was then well rammed with rammers made by inserting a 
 
112 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 handle in a section of a pile, except at the edges, where a rammer made of a 
 2-inch plank cut in the shape of a spade was used, to insure a perfect skin 
 of cement without any breaks. After this had been well rammed, another 
 layer of stone was placed and covered with mortar as before, and so on. 
 
 "The coping, which was made similar to the body of the pier, was fin- 
 ished by about \Yz inches of cement mixed with sand one to one, fluid 
 
 CRUSHING PLANT AND SIJVS. 
 
 n 
 
 Side Elevation, 
 
 Elevalion t>f 
 Rear Bent and Platform* 
 
 Front Elevalion 
 
 CONCRETE MIXING PLANT. 
 
 Side -Elevation 
 FIG. 90. STONE CRUSHER AND CONCRETE MIXER. IIJvINOIS AND MICHIGAN CANAI, 
 
 enough to be struck off by a straight edge, the top of the frame being 
 dressed and leveled for that purpose. 
 
 " After the pier had been completed the frames were removed and the 
 braces running through the piers cut off by a chisel inside the concrete. 
 Then, to make a smooth surface, the pier was thoroughly wet and plastered 
 with a mixture of one part sand to one part cement, after all the rough or 
 
THE COFFER-DAM PROCESS FOR PIERS. 
 
 loose portions had been scraped off. This was mainly done for appearance," 
 The mortar for the body of the pier was made of one part Alsen's Ger- 
 man Portland cement and four parts of sand. There was used about l^i 
 barrels of cement to a cubic yard of completed pier. In mixing the mortar 
 
 eleven ordinary pails 
 full of water were used 
 to one barrel of ce- 
 ment, which caused 
 the water to just ap- 
 pear on the surface 
 when the tamping was 
 done. 
 
 The lock walls on 
 the Illinois and Mis- 
 sissippi canal have 
 been constructed of 
 monolithic concrete 
 under Captain W. L. 
 Marshall, Corps of En- 
 gineers. The work 
 was executed under 
 L. L. Wheeler, en- 
 gineer in charge, from 
 whose account in the 
 report of the Chief of 
 Engineers for 1894, 
 the followingis taken: 
 "The rules adopt- 
 ed for the work were 
 adhered to and are 
 worthy of careful 
 study. 
 
 "I. The forms or 
 molds of the walls will 
 be divided by vertical 
 
 FIG. 91. AMERICAN HOIST AND DERRICK CO. 
 GUY DERRICK. 
 
 DOUBLE DRUM 
 
 partitions perpendicu- 
 lar to the longest axis 
 of the mass, and the walls be constructed by filling alternate sections. 
 
 "II. The sections will be filled in horizontal layers, well rammed, each 
 layer to be deposited before the 'initial set' of the previously deposited layer. 
 When the work of filling a section is begun it must proceed without inter- 
 mission to completion, working night and day if necessary. 
 
114 
 
 THE LOFFER-DAM PROCESS FOR PIERS. 
 
 "III. The facing and backing must go on simultaneously in the same 
 horizontal layers, using the same cement in the facing as in the backing, with 
 no defined lines of demarcation between the facing which contains no stone 
 and the concrete backing. 
 
 "IV. When the top surface of the coping is reached it will be finished 
 after ramming by cutting off the excess by a straight edge, and rubbed 
 
 smooth and hard by a float. 
 No plastering or wet finishing 
 coat will be allowed. 
 
 "V. The facing of the 
 walls will not be finished by 
 plastering or washing with 
 cement after the forms are re- 
 moved, nor dressed in any 
 manner beyond chiseling away 
 rough ridges should the plank 
 forming not be smooth. 
 FIG. 92. SINGLE DRUM HORSEPOWER. CON- "VI. The concrete shall 
 
 TRCATORS PI<ANT MFG. CO. V 
 
 will take, without water showing after ramming, or without 'quaking' upon 
 ramming. 
 
 "VII. At such intervals as may be necessary vertical wells, at least one 
 foot square will be formed along the mid- 
 dle of the masses of concrete, reaching to 
 near the bottom thereof. The masses of 
 concrete after forming will be kept shel- 
 tered from the sun, the outer surfaces 
 kept moist and the wells kept filled with 
 water until well set, or about three weeks. 
 The walls will then be filled with con- 
 crete. 
 
 "VIII. In preparing the cement for 
 mixing with other ingredients of con- 
 crete, from five to ten barrels will be. kept 
 thoroughly mixed dry, to guard against 
 chance barrels of defective cement, and FIG . 93._ D ouBLE DRUM HOIST ENGINE. 
 the necessary quantity of cement will be UDGERWOOD MFG. co. 
 
 taken for each batch from this mixture. 
 
 "IX. Two cements of different qualities shall not be used in the same 
 section, but as far as practicable each mass shall be homogeneous throughout, 
 but a slight excess of cement in the facing to reduce its capacity to absorb 
 water." 
 
THE COFFER-DAM PROCESS FOR PIERS. 1 1 5 
 
 The rate at which the concrete was deposited in the work was determined 
 by the rate of ramming, and but one yard every five minutes was deposited. 
 The forms (Fig. 89) were lined with dressed pine plank 4 by 8 inches on the 
 face, of uniform thickness, and with 2-inch rough plank on the back. 
 
 Rough plank is sometimes used on such work and lined with oiled paper, 
 or ordinary dressed plank may be used and coated with soft soap. In most 
 sections of the country crushed broken stone can be obtained, but owing to 
 the magnitude of this work a crusher was built (Fig. 90) and was found to 
 work very satisfactorily. The concrete mixer shown in Fig. 90 was oper- 
 ated by a 15-horse power portable engine. The proportions finally adopted 
 for the concrete were one of cement, three and one-third of gravel, and four 
 
 FIG. 94. LIDGERWOOD ELECTRIC HOIST. 
 
 of broken stone, while the facing and coping were composed of one part 
 cement and two parts of clean river sand. 
 
 That the sand for concrete be clean and sharp is very essential, and any 
 loam or dirt must be washed out. Equally essential is good, clean, sharp, 
 broken stone without dust or dirt. The cement used on the above work was 
 a German Portland, but several of the American Portlands are first-class and 
 will give as good results as the imported. 
 
 Where good, fresh cement is being supplied, a few tests to a carload will 
 be sufficient, and for cements of the grade of Atlas or Empire, the guarantee 
 of the manufacturer, supplemented by a few tests, should be sufficient, But 
 
1 1 6 THE COFFER-DAM PROCESS FOR PIERS. 
 
 for cements which have been shipped by water tests should be made from 
 every five or ten barrels. 
 
 The Atlas Cement Company recommend, for concrete laid in open air 
 on moist ground where great weight must be carried, one of cement, two of 
 clean sharp sand, and lour of 2-inch broken stone; this sand and cement to 
 be thoroughly mixed dry, then just enough water added to thoroughly 
 moisten, and the mass turned over at least twice, when the stone is to be 
 
 FIG. 95. UDGERWOOD CABI/EWAY CARRIAGE AND SKIP. 
 
 added in a thoroughly wet condition. This must then be put at once into the 
 molds and well rammed. 
 
 Where a solid bottom is to be built upon, the proportions of one of 
 cement, three of sand and six of broken stone are recommended. For 
 ordinary construction one of cement, four of sand and eight of broken 
 stone, while to obtain a concrete as strong as ordinary natural cement con- 
 crete, one of cement, five of sand and ten of broken stone can be used. 
 
THE COFFER-DAM PROCESS FOR PIERS. 1 1/ 
 
 The average cost of such concretes, including labor, tools, timber forms 
 and a fair profit to the contractor would be for the first $8 per yard, for the 
 second $7, for the third $6, and for the fourth $5. 
 
 Where the leveling course of concrete has been put in and the pier is to 
 be of stone, the footing course should be of carefully selected material. 
 They should be large stones with good beds, and should be as thick or pref- 
 erably thicker than the courses above. Where the bearing pressure does 
 not exceed two tons per square foot, the footing courses may be stepped by 
 allowing each course to project about one and one-third times its thickness, 
 depending of course on the quality of the stone. 
 
 The usual way of handling the material for foundations and piers, is to 
 boat it to the site, where it is placed by a stiff- leg derrick, or if guys can be 
 used, by a derrick with wire rope guys. The fittings for such derricks can 
 be obtained from a number of firms, an American Hoist and Derrick Company 
 outfit being shown in Fig. 91. This is rigged to be operated by a double drum 
 hoist, which can be one operated by horse power (Fig. 92) if the piers are 
 near the bank and if steam power is not available. The usual form, how- 
 ever, is a double drum steam hoist like the Lidgerwood machine shown in 
 Fig. 93. Where electric power is available an electric hoist (Fig. 94) should 
 be used, as it will be found much more convenient. 
 
 Works of any magnitude should, however, be fitted from the beginning 
 with a cableway, which will avoid the necessity of boating the materials, 
 erecting of large derricks, and facilitate in every way the prosecution of the 
 work, besides often making a balance on the right side of the ledger. The 
 Lidgerwood cableway on Dam No. 11 of the Great Kanawah river, a tower 
 of which can be seen in Fig. 9, had a span of 1,505.5 feet and carried a net 
 load of four tons on a main cable 2% inches in diameter. The stone quarry 
 was located on one bank and the stone was taken directly to the stone yard 
 and to the work in the river. A seam of coal in the quarry also supplied 
 fuel for the dredges and pumps, the coal being handled by the cableway, as 
 was also the material from the railroad siding on the opposite bank. 
 
 The details of these cableways have been developed and perfected to a 
 wonderful extent, as a result of their use on the Chicago Drainage channel. 
 The engine for operating one of these with a capacity of eight tons has 
 double 10x12 cylinders, the cranks being set at an angle of 90 degrees and 
 is provided with reversing link motion. The double drums regulate both 
 the hoist at a speed of 300 feet per minute and the travel along the cable at 
 1,000 feet per minute. A 70-horse power boiler is required. 
 
 The carriage and skip, which are automatic in action, are shown in Fig. 
 95, the capacity of those on the Drainage channel being 1.8 yards, and the 
 average of a month being about 600 yards per day of ten hours. The cost 
 of operation, including labor, fuel and everything except interest on plant 
 
US 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 and repairs was less than $18 per day or from three to four cents per yard. 
 
 The cableway on the Coosa dam and lock (Fig. 96) had a capaciiy of 
 
 about eight tons and made a round trip on an average of about three minuteSc 
 
 Such a plant is out of reach of high water and of trains where used over rail- 
 road tracks as at the North avenue bridge in Baltimore. 
 
 The Court street stone arch bridge at Rochester, N. Y., of eight spans, 
 was constructed with the aid of a cableway, which was also used ro remove 
 
THE COFFER-DAM PROCESS FOR PIERS. r ICj 
 
 the old bridge and piers. A cableway of one span was used to construct 
 the Melan concrete arch bridge at Topeka, Kan. The bridge has five spans 
 and a total length of 650 feet. During the extreme high water in the early 
 part of 1 897, ' when everything was completely inundated, and an ordinary 
 derrick plant would have been swept away, the cableway was high and dry 
 out of reach of the flood. 
 
 The prevailing low prices of contract work make it necessary to employ 
 every improvement on important engineering work, and the cableway has 
 doubtless come to stay as one of the most remarkable of our tools. 
 
ARTICLE X. 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 .LOCATION AND DESIGN OF PIERS. 
 
 IERS of a bridge cannot always be located with reference to easy con- 
 struction nor spaced at economical distances apart. In thickly settled 
 parts of a country, or as part of an existing line of communication, 
 the bridge must be located usually in a position previously determined, 
 and the piers can only be spaced with regard to economy, provided due 
 regard can at the same time be paid to the needs of navigation, gov- 
 ernment requirements and sufficient waterway. 
 
 Where the bridge is to be constructed in a new country, or upon a new 
 line of road, the crossing should be selected where the river is of moderate 
 width; that is, not so wide as to demand a structure of excessive length 
 and probably of excessive cost, nor so narrow that the current will be exceed- 
 ingly swift and make the foundations very difficult and costly to build, 
 unless, of course, it is narrow enough to admit of using a one span structure 
 at a reasonable cost. 
 
 On all the large navigable rivers, the cnannel is fixed and the length of 
 the channel span prescribed by law, as is also the method of procedure in 
 obtaining the approval of the government engineers. The Secretary of War 
 must be furnished with a copy of the state law authorizing the construction 
 of the bridge, certified to by the Secretary of State under seal; drawings in 
 triplicate showing the general plan of the bridge; a map in triplicate show- 
 ing the location of the bridge, giving for the distance of one mile above and 
 one-half mile below the proposed location, the high and low water lines 
 upon the banks of the stream, the direction and strength of the current at 
 high and low water, with the soundings accurately showing the bed of the 
 stream, and the location of any other bridge or bridges, such map to be suf- 
 ficiently in detail to enable the Secretary of War to judge of the proper loca- 
 tion of the bridge. In addition to the above, if the applicant is a corpora- 
 tion, there will be required a certified copy of their articles of incorpora- 
 tion, a certified copy of the minutes of the organization of the company, "and 
 an abstract of the minutes of the corporation, showing the present officers of 
 the company, all duly certified to. 
 
 When the location of the bridge has been made, a thorough examination 
 of the site must be instituted. Soundings must be made to determine the 
 depth of the stream at low water; ordinary and extreme high water lines 
 
 120 
 
THE COFFER-DAM PROCESS FOR PIERS. 121 
 
 must be established and the flow of the stream be obtained. A careful 
 examination must be carried out as to the character of the river bed, and 
 drillings made to learn the character and thickness of strata and the distance 
 to bedrock, as well as the quality of it. 
 
 Borings to a small depth may be made by hand drills (Fig. 97a), which 
 are operated by striking with a sledge and turned constantly to keep a round 
 hole, or if long and heavy they will cut their way, if simply raised up and 
 
 (Fig. 97a) 
 
 (Fig. 97b) 
 
 HAND DRILL AND SWAB. 
 
 allowed to drop, with their own weight. The hole is kept partly filled with 
 water and can be cleaned out with a small sand pump or with a swab (Fig. 
 ^7b) made from a stick slivered at the end, which will also bring up samples. 
 
 The Pierce steel prospecting augur is a tool, which can also be used 
 without a derrick to bore test holes from 10 to 50 feet into loose soils or clay. 
 Holes from 2^ to 6 inches in diameter can be drilled and samples obtained. 
 The augur can be turned either by hand wrenches or by horse power. 
 
 Where the borings are to be of an extensive character a well-drilling 
 machine can be utilized, such as shown in Fig. 98, and which can be run 
 onto an ordinary flat-boat and towed to place. 
 
 The tools for drilling are a temper screw for regulating the height of the 
 drill, a sinker bar to give the weight, steel jars and drilling bits. A sand 
 pump is used to clean the hole and obtain samples; rope spears, rope knives 
 and fishing tools to remove lost rope, tools and pebbles or other obstructions. 
 The drill holes, unless through rock, are cased with iron pipe which can be 
 withdrawn when the hole is completed. 
 
 The borings made by the Mississippi River Commission were very 
 extensive and a special tripod apparatus (Fig. 99) was devised with a view 
 to easy transportation and easy repair in the field. The tripod was 30 feet 
 in height, with a strong head or cap, surmounted by a galvanized iron guide 
 pipe 20 feet in height, in two sections, and held in place with guy ropes. 
 The men operating the tools stood upon the triangular platforms which were 
 attached to the legs. The casing was iron pipe in 10-feet lengths and 
 screwed together so as to present a smooth surface, while the bottom was 
 
122 THE COFFER-DAM PROCESS FOR PIERS. 
 
 provided with a steel cutting shoe, having a mouth slightly larger than the 
 pipe. The sinking is accomplished by driving and by twisting; the driving 
 being done by means of the clamp on the pipe and the maul sliding on the 
 pipe. (Fig. 100.) The weight of the maul is from 80 to 100 pounds and is 
 
 FIG. 98. STEAM POWER WELL 
 
 worked by three men giving it a lift of about 2 feet, the best results being 
 obtained when the men act in concert and give rapid blows. The removal 
 of the core and samples is accomplished by means of the various tools shown 
 
124 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 in Fig. 99, and requires great care and considerable experience. The pump 
 was raised and lowered by means of the reel attached to one leg of the 
 tripod, and its distance from the surface noted from graduations on the pump 
 rod. When the boring is completed the tube is withdrawn by a system of 
 compound levers, assisted by a set of differential blocks when necessary, as 
 the force exerted was often as much as the strength of the pipe at the joints. 
 The pebble tongs were for use in removing large pebbles which would not 
 enter' the pumps, and for recovering lost tools or the 
 pump itself in case of becoming detached. 
 
 The above account is taken from the report of 
 J. W. Nier, Assistant Engineer, to which reference 
 must be made for other details. 
 
 When the examination of the site has been com- 
 pleted and the borings finished, the form of founda- 
 tions may be decided upon, due weight being given 
 to good foundations and to the allowable expenditure. 
 Should the obtaining of good foundations be seen to 
 be very expensive, long spans must be adopted to re- 
 quire few piers in the river, but if inexpensive much 
 shorter spans, with more piers may be used. 
 
 The length of spans for a least cost of structure 
 was formerly assumed to be decided when the cost of 
 one span was made equal to the cost of one pier, and 
 for spans of certain capacity this might be approxi- 
 mately true, but a very neat mathematical solution 
 of this problem by Alfred D. Ottewell, Consulting 
 Engineer, was published in the Engineering News of 
 December 14, 1889. The total length of the struc- 
 ture in feet was represented by /, the number of spans 
 by n, the length of one span in feet /-f- n by s, the 
 cost of one span in dollars by c, the cost of one pier in 
 dollars by^>, the total cost of the structure in dollars 
 by y, while a and b are constants. ' 
 
 From the estimated cost of a large number of spans, a curve of costs was 
 plotted and the following equation of a parabola deduced : 
 
 c = a 
 
 FIG. 100. CLAMP AND 
 
 Since there are n spans and n + 1 piers, the total cost of the structure 
 would be 
 
 Then by substituting the value of c from (1), reducing and making the first 
 
THE COFFER-DAM PROCESS FOR PIERS. 125 
 
 differential coefficient equal to zero the cost of one pier is obtained, which 
 will make the total cost of the structure a minimum or 
 
 Or when the cost of a pier has been estimated, the economical length of 
 span may be found by a transposition of the above formula : 
 
 s = y"ab + 400 + pb (4) 
 
 The values of a and b may be found by substituting in equation (1) com- 
 puted values of the cost of a number of spans for an actual loading. Values 
 of 5, p and c, may then be computed and tabulated for spans from 100 feet 
 upwards, as formula (1) is not true for shorter lengths. 
 
 In an actual calculation for B. & O. R. R. loading, which consists of two 
 125-ton engines followed by a 4,000-pound per lineal foot trainload, a was 
 found equal to 1950 and b to 3.05. Assuming a case where the length of 
 the bridge is 700 feet, where the height of the piers will average 25 feet, 
 and the average cost of piers and abutments be $4,310, then from formula 
 (4) the economical span will be found equal to 140 feet. The total cost of 
 the structure will be found, by using formula (1), and the cost of piers as 
 above, to be $59,700. While with only four spans of 175 feet, the total cost 
 would exceed $60, 800, and with six spans of 117 feet, would be about $61, 400. 
 
 Should there be any doubt as to the ease of obtaining foundations, the 
 prudent engineer might deem it wise, however, to build the four-span 
 structure and avoid the risk and delay which would be caused by another 
 foundation in the river. 
 
 After deciding upon the number and location of the piers, they must be 
 designed with reference both to their being as slight obstructions to the 
 water as possible and to their architectural appearance. 
 
 The design of piers has been given particular attention by Geo. S. 
 Morison, Consulting Engineer, whose work on the bridges across our great 
 rivers is notable for its strength, simplicity and finished appearance. In a 
 recent lecture he describes the process of the design of some large piers : 
 "Fourteen years ago I had occasion to design a bridge pier for a bridge 
 across one of our Western rivers, and I tried to make an ornamental pier. 
 When the plans were completed I did not like them. One change after 
 another was made, all tending to simplicity. Finally the plans were done. 
 From high water down, the pier was adapted to pass the water with the 
 least disturbance; it had parallel sides and the ends were formed of two cir- 
 cular arcs meeting. Above high water the ends were made semi-circular 
 instead of being pointed. The pier was built throughout with a batter of 
 one in twenty-four. A coping two feet wider than the body of the pier pro- 
 jected far enough to shed water, and the projection was divided between 
 
<;. 101. I'IKK OK OMAHA IJRIIXIK, UNION PACIFIC. 
 
FHE COFFER-DAM PROCESS FOR PIERS. 
 
 12; 
 
 the coping and the course below. Another coping with a less projection 
 surmounted the pointed ends where the shape was changed. It was as 
 simple a pier as could be built, and in every way fitted to do its duty. I 
 had started to make a handsome pier. The pier that was exactly what was 
 wanted for the work, was the only one that satisfied the demands of beauty. 
 Forty-three piers of precisely this design (no change having been made 
 except in the varying dimen- 
 sions required for different 
 structures), besides eight oth- 
 ers in which only the lower 
 parts are modified, are now , 
 standing in eleven different 
 bridges across three great 
 Western rivers. In designing 
 a pier it must be remembered 
 that the portion of the pier 
 below the water has more to 
 do with the- free passage of 
 the water than that above 
 water. In a deep river the 
 model form of the pier should 
 begin near the bottom of the 
 river and not at low water. 
 Many rivers in flood time 
 carry a great amount of drift. 
 A pier like that which I have 
 described catches but little of 
 this drift. If, however, a rec- 
 tangular foundation termin- 
 ates but little below water, that 
 foundation may uoth disturb 
 the current and catch the drift. ' ' 
 
 The piers of the Omaha bridge, which carries the Union Pacific across 
 the Missouri river, are illustrated in Fig. 101, and were constructed as 
 described and are among the most beautiful piers in this country. 
 
 In Europe, where money is more lavishly expended on great works of 
 engineering, piers of great architectural beauty are much more frequent. 
 The Russian Government railways, which have seemingly been constructed 
 without regard to expense, have many beautiful examples of bridge 
 masonry and piers; the view of one of them (Fig. 102) with curved ends, 
 shows the elegant and massive character of the masonry. While extremely 
 
 FIG. 102. RUSSIAN PIER, RUSSIAN STATE 
 RAILWAYS. 
 
FIG. lOo. CRESY'S EXPERIMENTS ON THE FORM OF IMKKS. 
 
THE COFFER-DAM PROCESS FOR PIERS. 129 
 
 simple in design, the cut stone coping and the moulded corbel course below 
 give it a finish which cannot be surpassed. 
 
 The design of piers for strength and stability is fully treated in Baker's 
 Masonry Construction, but some experiments, which were made with ref- 
 erence to the proper form to occasion the least resistance, will be quoted at 
 length from Cresy. 
 
 The introduction of piers into a channel gives rise to a great disturbance 
 in the velocity and flow of the water. Rapid currents are formed which 
 cause the bed of the stream to become washed and the foundations to be 
 endangered; eddies are created which are likewise undesirable, and it 
 becomes necessary to adopt such a form for the ends of the piers that the 
 disturbance to the flow shall be small. 
 
 M. Bossut, in a French work on jetties, thought to have solved this 
 problem by mathemathics, his conclusion being that the starling should be 
 triangular, the nose being a right angle. 
 
 M. Dubuat, in his "Principles of Hydraulics," gave another solution 
 which was more nearly the truth, in that he arrived at the conclusion that 
 the faces of the starling should be convex cnrves. The true form is most 
 nearly reached when these curves are tangent to the sides of the pier, and 
 further than this, regard must be paid to giving enough solidity to the 
 starlings to protect them from ice and drift. A happy medium would seem 
 to be reached, by making the curves with a radius equal to one-sixth of the 
 circumference, described on the sides of an equilateral triangle. 
 
 Experiments were made with models of different forms, which were 
 placed in a rectangular canal between boards of 50 centimeters in length, in 
 which the water flowed about 40 millimeters in height, the models being 15 
 centimeters in thickness. By means of a fall, the water was given a velocity 
 of 3 meters 9 centimeters per second, the contraction, eddies and currents 
 being carefully measured. The first experiment was made on a pier (Fig. 
 103 A) with rectangular starling. An eddy was formed before the pier 34 
 millimeters high, in a nearly circular band A, falling nearly vertical at the 
 corner. There were two other currents along the faces of the pier, the height 
 of which can be seen in the cross-sections. 
 
 The second experiment (Fig. 103B) was with a triangular starling, the 
 nose being a right angle. It formed a less obstruction than the square end, 
 but the fall at the shoulder was as deep and more dangerous, while eddies 
 were formed as seen in the sections. 
 
 The third one (Fig. 103C) had a semi-circular starling. The eddy was 
 not so wide, but nearly as high. 
 
 The fourth model had a triangular starling, with an angle of 60 degrees 
 at the nose. (Fig. 103D.) The eddy was less, as was also the fall at the 
 shoulder. 
 
130 
 
 THE COFFER-DAM PROCESS FOR PIERS. 
 
 The starling in the fifth was formed by two circular arcs, tangent to the 
 sides and described on the sides of an equilateral triangle. (Fig. 103E.) 
 The eddy was small and there was no fall at the shoulder. 
 
 FIG. 104. CRESY'S EXPERIMENTS ON THE FORM OF PIERS. 
 
 The sixth (Fig. 103F) was a model, the plan of which was an ellipse, of 
 which the small diameter was one-fourth the length, and the eddy was less 
 than any of the others. 
 
 The seventh model (Fig. 104 A) had a starling with concave faces, such 
 as is sometimes used where the wing wall meets an abutment. It produced 
 the most dangerous currents of all. 
 
THE COFFER-DAM PROCESS FOR PIERS. 131 
 
 The eighth (Fig. 104B) was of the same form as Fig. 103E, but the 
 water was supposed to mount the springing of the arch. 
 
 The ninth and tenth experiments (Figs. 104C and 104D) were on the 
 same forms as Figs. 103E and 103F, but the current had a velocity of 4 
 meters 87 centimeters per second, such as a river would have in its overflow. 
 The eddy (Fig. 104C) rose to nearly twice the height, as was the case with 
 the lesser velocity, and while there was no fall, the inclination formed along 
 the faces was more rapid. 
 
 The effect with this velocity on the elliptical pier (Fig. 104D) was sim- 
 ilar to the lesser velocity but more marked. It may thus be concluded that 
 the elliptical section offers the least resistance to the current and occasions 
 the least contraction, while the form with convex starling comes next, and 
 of piers with triangular starlings the one with the 60-degree nose is the best. 
 
 Where ice is to be provided for, the nose is often inclined to allow large 
 cakes to mount it and break in two, without doing further damage. For 
 any large or important structure, the design of the piers should receive a 
 great deal of study, and be designed not only with reference to their theo- 
 retical form, but with reference to the form of pier which has shown the best 
 results practically and has been found to be best suited to the velocity of the 
 stream in which they are to be built, and to best withstand the drift and ice 
 that may be met with, giving at the same time all the consideration possible 
 to the architectural effect and to the harmony with the entire structure. 
 
APPENDIX. 
 
 SELECTIONS FROM SPECIFICATIONS. 
 
 SPECIFICATIONS FOR COFFER-DAMS AND FOUNDATIONS, 
 OHIO RIVER MOVABLE DAMS. 
 
 MAJOR W. H. HEUER, U. S. Engineer. 
 
 GENERAL DESCRIPTION. 
 
 The site of Dam No. 2 is on the Ohio River, distant from Pittsburg, Pa., ioi miles, 
 and adjacent on the right bank to the Pittsburg, Ft. Wayne and Chicago Railway. It 
 has Neville Island on the left bank, and is accessible by street cars from Pittsburg. 
 
 The lock is to be located on the left bank of the Ohio River, immediately behind 
 Merrimans dyke. It will be in general dimensions the' same as locks Nos. i and 6, 
 viz., no feel wide and 600 feet long. 
 
 SPECIAL DESCRIPTION. 
 
 The river bed at No. 2 consists of gravel throughout, and the excavations will be 
 made to a depth sufficient to insure a permanent and enduring foundation, which will 
 ordinarily be 14 feet below the gate sill, but may be otherwise, as the Engineer, in his 
 judgment, may direct. 
 
 The work will conform to the drawingsexhibited, and to such others, in explanation 
 of details or modifications of plans, as may be furnished from time to time during con- 
 struction. 
 
 CONTRACTOR TO FURNISH ALL MATERIAL AND WORK. It is understood and agreed 
 that the contractor, under his contract prices for work in place, is to furnish and pay 
 for all materials, stone, cement, sand, earth, timber, material for coffer-dam and protec- 
 tion cribs, excavation, lock-filling and discharging valves (set in masonry), flushing 
 valves, anchor bolts, lock-gate tracks, and everything entering into or connected with 
 either the permanent or temporary construction, and he is also to supply and pay for all 
 work : skilled and otherwise, required to prepare and place the materials, and complete 
 the work according to the drawings and these specifications. 
 
 CONTRACT TO INCLUDE The contract will cover the construction and completion of 
 the foundation, masonry and timber work of the lock, including both land and river 
 walls, the gate-recess walls, the foundations of the lock-gate tracks, the guiding walls 
 above and below the lock, the pipe and flushing conduits, the drift chute, the founda- 
 
 133 
 
134 APPENDIX 
 
 tions for the power-house and lock-keepers' residence, and every such other permanent 
 construction as shall be shown upon the drawings. It shall also include the clearing 
 of the land necessary for the proper execution of the work embraced, in this contract, 
 all pumping and bailing, dredging and excavation, puddling and embankment, the con- 
 struction of all coffer-dams, stone masonry, concrete and brick masonry, timber work 
 and iron work, and all such other work which, in the judgment of the Engineer, is nec- 
 essary and included in the proper completion of the contract. 
 
 TOOLS, MACHINERY, BUILDINGS, ETC. The contractor, without cost to the United 
 States, shall furnish all appliances, dredges, pumps and pumping machinery, boats, 
 tools, derricks, tramways, foot walks, roads and landings, and all needful temporary 
 buildings and shops. 
 
 COFFER-DAM. 
 
 SHEETING. The coffer-dam, about 1500 feet in length, shall be built as shown gen- 
 erally by the drawings exhibited, and as directed by the Engineer. It shall be 14 feet 
 high above the sill of the lock, and shall consist of two walls or rows of plank sheeting, 
 spaced 12 feet apart in the clear, driven or set firmly from i to 2 feet into the river bed, 
 and supported laterally by horizontal longitudinal stringers, the latter being spaced 
 at varying intervals, increasing in width from the bottom to the top, and to be suffi- 
 ciently and firmly bolted together transversely with iron rods passing through the 
 coffer-dam horizontally from the rows of stringers on the one side to the corresponding 
 rows on the other, against which the vertical plank sheeting shall be securely spiked. 
 
 FILLING AND DECKING. The interior, or space between the walls of sheeting, shall 
 be filled with heavy dredged river-bed or other material not liable to wash, and to be 
 covered over with a suitable decking of plank (to protect it from injury in case of being 
 submerged by floods), all complete as shown on the drawings. 
 
 PILING AND CRIBS TO PROTECT. At the upper outer corner of the coffer-dam shall 
 be placed a crib built of framing timber and filled with riprap stone ; from the upper 
 corner of the crib, at an angle of 45 with the axis of the current, a line of piling, spaced 
 5 feet apart, firmly bolted together with waling pieces, shall be driven to the shore to 
 form a protection to the coffer-dam ; also outside and along the coffer-dam, from the 
 upper outer corner to the lower corner, clusters of piles, firmly bound or bolted 
 together, shall be driven at intervals of about 80 feet. The tops of all piling shall be 
 sawed off to a uniform height, of 2 feet above the coffer-dam. Protection cribs shall be 
 placed at such other points along the coffer-dam as may be shown upon drawings. 
 
 How PAID FOR. Bidders will state a price per lineal foot of coffer-dam completed. 
 No payment will be made for any portion thereof until the entire coffer-dam is completed. 
 Drawings will be furnished, showing the general type of the coffer-dam and its manner 
 of construction, and every detail necessary for intelligent bidding. Should any work 
 on the outside of the coffer be necessary, such as gravel filling or riprapping, it shall 
 be paid for at the price bid for gravel filling, riprapping, etc. If, owing to the nature 
 of the river bed, it shall be found impossible to drive the plank sheeting to the required 
 depth, then the contractor, after driving the sheeting as deep as possible without injury, 
 and in lieu of driving it to its full depth, shall fill around the outside of the walls with 
 the same material as is used in filling the coffer-dam, to the height of 4 feet above the 
 surface of the river bed, and for which no extra compensation will be allowed. 
 
 REMOVAL OF. The contractor will be required to remove the coffer-dam and its be- 
 longings at his own cost. The time and manner of the removal of the coffer-dam, or 
 any part thereof, and the place to deposit the materials, shall be prescribed by the 
 Engineer. 
 
 To BELONG TO THE UNITED STATES. It is understood and agreed that the payments 
 made for the coffer-dam, including the crib and pile protection, shall cover the entire 
 cost thereof to the United States, and by virtue thereof they shalj become the property 
 of the United States. The contractor, however, must maintain the same and make all 
 needed repairs to same during the existence of the contract, without expense to the 
 United States. 
 
 DEPOSIT WITHIN THE COFFER-DAM. Material washed or left in the space enclosed 
 by the coffer-dam by freshets shall be removed by the contractor, as directed, at his 
 price for common excavation, which price shall cover all necessary cleaning and scrub- 
 bing. No payment will be made, however, for removing material washed into the enclos- 
 
APPENDIX. 135 
 
 lire from the coffer-dam itself or from any deposit made by the contractor on or above 
 the works. 
 
 MATERIAL AND WORKMANSHIP. 
 
 TEMPORARY PILING shall include all piles driven for the protection of the coffer- 
 dam and "deadmen" for derricks. They shall be of good quality, round oak timber, 
 not less than 12" diameter at the butt, and of length varying from 20 to 25 feet, and 
 longer if necessary. 
 
 SHEET PILING. In excavating for foundations, should quick-sand or fine-sand- 
 carrying water be encountered, close sheet piling will be required to be driven to what- 
 ever extent the Engineer may direct. 
 
 SHEETING. The sheeting shall include the walls and decking of the coffer-dam, in- 
 cluding the stringers ; also such shoring as may be directed by the Engineer to remain 
 in the finished structure. It shall consist of the best quality of hemlock obtainable, 
 and must be in all cases satisfactory to the Engineer in charge. 
 
 GRAVEL OR EARTH FILLING. Gravel or earth filling will include all material used in 
 filling the land-wall enclosure, back of the guiding walls, etc. It does not include any 
 filling in the construction of the coffer-dam. 
 
 STONE FILLING shall include all stone placed in the protection cribs or any riprap 
 stone ordered for the protection of the work. 
 
 CRIB WORK shall be built of hemlock framing timber framed together in square 
 bins and securely bolted together by iron drift-bolts. The interior of the cribs shall be 
 filled with riprap stone, and should the Engineer deem it necessary such riprap stone 
 shall be placed on the outside of the crib. The whole to be built as shown by the 
 drawings. 
 
 FRAMING TIMBER. For all temporary crib work, also the permanent crib at the head 
 of the upper guiding wall, framing timber shall be used. No stick shall be less than 
 10" X 10'' in section. 
 
 " Framing timber " is a commercial term for a class of timber hewn to various sizes. 
 
 EXCAVATION. 
 
 To INCLUDE. It shall include the removal of all gravel or other material to the 
 depth required for the lock and its upper and lower entrances, the gate recesses, Poiree- 
 dam and gate-track foundations, for the foundations of all walls, and for all conduits or 
 wells, and all such other material as may be found necessary in the judgment of the 
 Engineer to be removed for foundations and otherwise in permanent construction. It 
 will include all dredging and all material excavated of whatever nature, however 
 removed, for foundations and for site of coffer-dam. 
 
 LINES, SLOPES, AND GRADES FOR. All excavations shall conform to such lines, slopes, 
 and grades as may be given by the Engineer, and anything taken out beyond such 
 given limits will not be paid for by the United States. 
 
 MATERIAL TO BE DEPOSITED. Excavated material is to be deposited as and where 
 directed by the Engineer. It shall be deposited in such manner as not to interfere 
 with present or proposed navigation. Material of any kind deposited by the contractor 
 in absence of, or in disregard of. instructions, shall, if required by the Engineer, be 
 removed by the contractor at his own cost. 
 
 SHORING. All excavation for foundation shall be securely shored and thus main- 
 tained until the foundation has been sufficiently advanced to dispense with the same, 
 when it may remain or be removed at the discretion of the Engineer. 
 
 DREDGF.S AND PUMPS. The contractor will be required to employ, at the same time, 
 not less than two suitable steam dredges at excavating and filling; and for pumping 
 he must keep at least three good sufficient pumping outfits, with pumps, engines, and 
 boats complete, in or always ready for operation. The dredges must be equipped to do 
 effective work to a depth of 28 feet. 
 
APPENDIX. 
 
 FOUNDATIONS. 
 
 CHANGES OR MODIFICATIONS OF. The character of the river bed and of the proposed 
 foundations for the different parts of the work is shown in general on the drawings and 
 cross-sections exhibited, and it is understood that the United States shall have the 
 power to make any changes in the plans of the foundations that may, in the judgment 
 of the Engineer, be considered advisable after examinations made, as the excavations 
 proceed within the coffer-dam after it is pumped out and it is understood and agreed 
 that the contractor shall have or make no claim against the United States on account 
 of any such changes in or modifications of the plans of the foundations, or on account 
 of any increase or decrease in the depth of same, under or over those referred to herein 
 or shown on the drawings exhibited. 
 
 MASONRY. 
 
 CEMENT. Cement will be of uniform quality, setting well both in air and water, and 
 free from anything that will cause the mortar to swell, crack, or scale. It shall be put 
 up in strong, sound barrels, well lined with paper so as to be reasonably protected from 
 air and moisture. The average net weight of the barrels shall be not less than 265 
 pounds, unless expressly so stated in the proposal. Each barrel must be labeled with 
 the name of the brand and of the manufacturer. 
 
 In general, ten barrels of every one hundred will be tested. 
 
 The cement must stand .the following tests ; Fineness At least 85 per cent must 
 pass a sieve of 6400 meshes to the inch. Setting Cement must be moderately slow 
 setting ; it must not begin to set within fifteen minutes, as determined by Vicat needle 
 1/12 inch in diameter with 1/4 pound load, and it shall not bear the weight of one 
 pound on wire 1/24 inch in diameter within thirty minutes, but must bear such weight 
 within one hour and a half. Strength The minimum tensile strength per square inch 
 of briquettes of neat cement mixed with about 33 per cent of water by weight, and 
 exposed in air for one hour, and the remainder of 24 hours in water, shall be not 
 less than 50 pounds ; with longer time, whether in air or water, there must be a 
 decided increase of strength ; it must also test to the satisfaction of the Engineer when 
 mixed with sand. The tests for setting will be made at a temperature of air and water 
 of about 75 Fahrenheit. All other tests will be made at a temperature above 6o 3 
 Fahrenheit. The cement will be subject to inspection at all times, and must be kept 
 well housed. 
 
 SAND. The sand used must be clean, sharp, washed, river sand, satisfactory to 
 the Engineer. 
 
 MORTAR. To be composed generally of two parts of sand to one of cement ; when 
 required, and whenever thought necessary by the Engineer, it shall be made richer. 
 It must be thoroughly mixed and used before it has begun to set. If required by the 
 Engineer, the mortar beds will be protected from the sun. 
 
 POINTING.' All face work is to be pointed, as fast as the work progresses, with stiff 
 mortar, mixed, one of sand to one of Portland cement, thoroughly hammered in and 
 finished with proper tools ; before the final acceptance ot the work all face masonry 
 which at that time does not appear properly pointed shall be repointed by the con- 
 tractor to the satisfaction of the Engineer, without extra cost. 
 
 FROST. Masonry will not be executed during freezing weather, nor when, in the 
 judgment of the Engineer or his agent, it is likely to fieeze before the rnortar shall 
 set. To guard against injury from frost all new a^nd unfinished work shall be properly 
 protected by the contractor at his own cost. 
 
 VOIDS AND OPENINGS. Due regard shall be had in the construction of all masonry 
 w r alls to leave all necessary voids or openings for conduits or wells, or for such other 
 purposes as may be required by the Engineer. 
 
 ASHLAR. It shall comprise such part of the walls as is built of stone, with point- 
 dressed face, and beds and joints smoothly and squarely dressed. 
 
 QUALITY OF STONE. All stone shall be perfectly sound, strong, hard, free from in- 
 jurious seams, and in all respects satisfactory to the Engineer. Stone to be such as 
 
APPENDIX. 137 
 
 can be truly wrought to such Hues and surfaces, whether curved or plain, as may be re- 
 quired. No stone shall be used which weighs less than 135 pounds to the cubic foot. 
 
 SAMPLES OF STONE Each bidder must deposit at this office, all charges prepaid, 
 before the bids are opened, a 6-inch cubical block of the stone he proposes to furnish, 
 and state the quarry from which it was obtained. The quality of the stone must be at 
 least equal to that of the sample. The sample must be truly squared, and dressed on 
 four sides ; one side must be hammer-dressed, one side smooth-dressed and rubbed, 
 and one side pitch-dressed. The other two sides are to be left with quarry face. 
 
 STONE MAY BE REJECTED. The United States reserves the right to reject any 
 stone not deemed suitable, or which, during the execution of the contract, shall be 
 found defective. The beds of the stone must be their natural quarry beds. No lewis 
 or dog holes, letters, or marks of any kind will be allowed on any dressed face of stone, 
 but each face shall have left on it a boss for lifting, to be removed by the contractor 
 after the stone has been set. 
 
 DRESSING OF STONE. Stone must be accurately cut, square and true, and the faces 
 must be pitch draughted and point-dressed to a plane with the draught, forming an 
 approximately smooth surface. The beds must be smoothly and squarely dressed, full 
 length and width. The vertical joints must be dressed to a depth of not less than 18 
 inches from the face, and the allowance for joints must not exceed 3/8 inch. One- 
 third of the stone in each course must be headers. All stones not accurately dressed 
 will be rejected. All dressed stone must have the dimensions plainly marked on one 
 end. 
 
 DIMENSIONS. The cut-stone stretchers must be not less than 3 feet nor more than 5 
 feet long, and their width must be not less than \\ times the height of the course to 
 which they belong. The width of the headers must be not less than \\ times their 
 height, and their length must be at least double their breadth, unless otherwise 
 ordered. The thickness of courses includes the joint, which will be 3/8 inch. . 
 
 LAYING STONE MASONRY. The faces of the walls shall be accurately laid to the 
 lines indicated on the drawings, or as, directed by the Engineer. All stones to be well 
 laid to proper lines, in full beds of mortar, and settled in place with a wooden maul ; 
 the use of grout is prohibited. No dressing, except in special cases, and by permission 
 of the Engineer, will be allowed on backing after it is laid in the wall. The bond of 
 stone shall in no case be less than 9 inches. The walls will be laid in horizontal 
 courses throughout, each course to be of uniform height through the wall. Heights 
 and arrangements of courses to be determined by the Engineer. When laying masonry 
 the site for the stone shall be thoroughly cleaned with a scrub broom and moistened ; 
 and the stone shall always be cleaned and well moistened before being set. Not more 
 than three unfinished courses of face stone will be permitted upon the wall at the same 
 time, without special permission from the Engineer in each case. Proper machinery 
 must be used in handling the stone , face stone shall not be disfigured by use of plug 
 or grabs. Any stone chipped or spalled shall be rejected. Stones having defects con- 
 cealed by cement or otherwise will be rejected on that account alone. 
 
 COPING. The coping will be of the same class and quality of stone described in 
 ashlar masonry. It will be carefully and truly cut to forms and dimensions given, 
 from the best stone , it will be cranda'lled on all outer faces ; the exposed edges of the 
 coping to be rounded to a radius of 3 inches and chiseled smooth where required. 
 Beds and vertical joints to be pointed true and full throughout and be laid with 3/8- 
 inch joints. 
 
 The coping is to be doweled as required by the Engineer with round iron. The 
 dowels to be furnished and placed by the contractor. The drilling for and placing of 
 the dowels will be covered by the price for " Bolt Holes in Masonry." The dowels will 
 be set in Portland cement. 
 
 RUBBLE STONE. 
 
 QUALITY AND DIMENSIONS OF. Rubble stone must be sound, hard, and durable, 
 free from seams, scale, earthy matter, and other defects. Rubble stone shall in gen- 
 eral be not less than 3/4 of a cubic foot in size. It must be in fair shape for laying in 
 the face of the walls without dressing. No spalls will be allowed. 
 
 LAYING. The stone must be laid on their natural bed in full beds of hydraulic 
 
138 APPENDIX. 
 
 cement mortar, with all joints and voids well filled with mortar. Leveling up under 
 stones with small chips or spalls will not be allowed. 
 
 The stone shall be carefully selected for the outer face so as to have vertical joints 
 and present a good face of broken rough masonry. 
 
 CONCRETE. 
 
 COMPOSITION OF. Concrete shall be composed of satisfactory cement and river 
 gravel ; the latter, should it be of an approved quality, shall be taken from the various 
 excavations of the lock and its walls. This gravel generally has a sufficient volume 
 of sand to fill all voids , should there be a deficiency of sand in any portion of the 
 gravel the contractor will be required to supply said deficiency by good, sharp, washed, 
 river sand. The quantity of cement to be used will generally be about 20 per cent 
 greater than the volume of voids in. sand and gravel. 
 
 MIXING AND PLACING OF. The concrete is to be well and rapidly mixed by 
 machinery, as may be required by the Engineer, unless otherwise specified. It will be 
 deposited in layers not more than 8 inches thick ; wherever and whenever required, 
 the layers will be thinner than 8 inches, and all thoroughly rammed by such process 
 as the Engineer may approve. 
 
 RIVER WALL. In the river wall of the lock the concrete shall be laid in courses of 
 a thickness corresponding to the adjoining courses of ashlar masonry. It shall be 
 filled in flush with the top of each course before the next course of ashlar above shall 
 be laid. 
 
 Before putting in the concrete of any course the bed and adjoining course of ashlar 
 shall be thoroughly wetted so that no dry surface may come in contact with the fresh 
 concrete, destroying its power of adhesion by absorbing its moisture. 
 
 In order that the work once begun may progress without delay all cut stone 
 needed for the ashlar facing shall be on the ground when the concrete foundation has 
 been completed. 
 
 TIMBER IN PERMANENT CONSTRUCTION. 
 
 To CONSIST OF all timber used in the timber facing of the lock walls and the 
 guide walls ; all timber cribbing in the gate-track and Poiree dam foundations ; the 
 oak sheeting at the head of the guide walls ; and such other timber in permanent con- 
 struction as shall be shown upon the drawings. 
 
 GENERAL QUALITY AND DIMENSIONS. All timber must be first class, and any of 
 inferior quality will be rejected. Sap-wood in any stick will cause its rejection. The 
 timber must be free from black or rotten knots, wane edges, wind shakes, dose, or 
 other imperfections. Firm sound knots, if not too numerous, will not be considered 
 defects. Timber must be full to size, true, and out of wind, and when required must 
 be sawed large enough to dress down to required dimensions. The timber will be 
 inspected on arrival at the work, and if found to be defective will be rejected. 
 
 OAK. Oak timber must be taken from the best quality live white oak sawed timber. 
 
 WHITE PINE. Shall consist of the best quality of clear white pine obtainable. 
 
 HEMLOCK. Shall be the best quality of hemlock obtainable. 
 
 FRAMING, ASSEMBLING, AND PAINTING. All timber must be accurately framed, 
 fitted, and assembled, according to detailed drawings and directions. As the timber 
 is framed it shall be painted about the ends and elsewhere as may be required to pre- 
 vent checking. The paints for this will be furnished and applied by the contractor, 
 and covered in his price for " Timber in Permanent Construction " 
 
 TIMBER FACING, UPRIGHTS. AND SHEETING shall be constructed of oak, and shall 
 consist of uprights spaced at intervals of 6 feet, center to center, anchored to the con- 
 crete masonry by tee-head screw bolts as shown on drawings. To the uprights shall 
 be bolted, with wrought-iron screw bolts, oak sheeting 6 inches thick. 
 
 NOSING TIMBER shall extend along the top of the guide wall, forming a cap to the 
 uprights and securely bolted to them, as shown on the drawings. The top surface of 
 the nosing shall be flush with the top of the concrete masonry wall. 
 
 OAK SHEETING. This refers to the sheeting on the upper faces of the protection 
 
APPENDIX. 139 
 
 crib for the upper guiding wall at the upper end thereof. It shalf be spiked on and 
 firmly held in place with iron bands or straps bolted to the framing timbers of the crib, 
 if, in' the judgment of the Engineer, this may be deemed necessary. 
 
 SUPERVISION AND MEASUREMENT OF WORK. 
 
 INSPECTION, REJECTED MATERIAL, ETC. The works will be conducted under the 
 direction of the local or resident Engineer, who shall have power to prescribe the order 
 and manner of executing the same in all its parts ; of inspecting and rejecting ma- 
 terials, work, and workmanship which, in his judgment, do not conform to the draw- 
 ings that may be furnished from time to time, or to these specifications. And any 
 material, work, or workmanship so rejected by him shall be kept out of or removed 
 from the finished work, and no estimate or payment shall be made until such material, 
 work, or workmanship be so removed. 
 
 When so required rejected material shall be piled up in sight near the works and 
 kept there until the Engineer gives permission to have it removed. 
 
 The United States will keep inspectors on the work who will receive instructions 
 from the resident Engineer. They will have power to object to any materials, work, 
 or workmanship. Any material, work, or workmanship objected to by the inspectors 
 shall be kept out of or removed from the finished work, unless in each particular case the 
 objections of the inspector shall be overruled by the local or resident Engineer ; and, 
 unless the objection be so overruled, no estimate or payment shall be made until such 
 material, work, or workmanship be so removed. 
 
 The local or resident Engineer shall have power to overrule or rescind any or all 
 objections or decisions of the inspector. 
 
 The decision of the United States Engineer Officer in charge of the works shall be 
 final and conclusive upon all matters relating to the work and upon all questions 
 arising out of these specifications, and from his decision there shall be no appeal. 
 
 FAILURE TO PROSECUTE OR PROTECT WORKS. If at any time the contractor shall 
 refuse or fail to prosecute the work or provide for carrying on the same as directed by 
 the Engineer, or fail to properly protect any part of the work, permanent or tem- 
 porary, the Engineer shall have power to employ men, to purchase or otherwise provide 
 materials, tools, machinery, etc., and put the work in proper advancement or condition, 
 and the entire cost of so doing shall be deducted from payments to be made under this 
 contract. 
 
 COMPLETE WORK REQUIRED. The contractor is not to take advantage of any 
 omissions of details in drawings or specifications, or errors in either, but he will be 
 required to do everything which may be necessary to carry out the contract in good 
 faith, which contemplates everything complete, in good working order, of good 
 material, with accurate workmanship, skillfully fitted and properly connected and put 
 together. Any point not clearly understood is to be referred to the Engineer for 
 decision. 
 
 CHANGES. Should any changes in the details of the shape, arrangement, or fitting 
 of the parts be deemed necessary or advisable in the progress of the work, they must 
 be made by the contractor, and a fair allowance will be paid for any changes which, 
 in the judgment of the Engineer in charge, materially increases the cost of the work. 
 
 MEASUREMENT. Measurement of all work and material shall be made in place, 
 unless otherwise specified. 
 
 COFFER-DAM. The price per lineal foot of coffer-dam shall include all material, 
 lumber, iron, and gravel entering into its construction. A profile of the location will 
 be furnished, showing a section of the river bed over which the coffer-dam is located, 
 so that the contractor may estimate the amount of each kind of material required. 
 
 PILING. Temporary piling shall be measured in lineal feet, and measurement shall 
 be allowed for total length of piling used. 
 
 SHEETING This will include all lumber used for temporary purposes, in shoring 
 of excavations, or for forms necessarv to sustain any concrete masonry until it has 
 become sufficiently hardened. Sheeting required by the Engineer to remain in the 
 finished structure shall be paid for at the contractor's price per thousand feet B. M. 
 All temporary sheeting not remaining in the finished structure shall be included in the 
 contractor's unit price for material in place, and no estimate will be made thereof by 
 
140 APPENDIX. 
 
 the Engineer. Coffer-dam sheeting will be included in the contractor's price per lineal 
 foot of coffer-dam. 
 
 FILLING. Gravel filling will be measured in the fill, and will not include any filling 
 placed in the coffer-dam as coffer-dam filling. 
 
 Stone filling shall include all riprap work, either temporary or permanent. 
 
 EXCAVATION. Excavation will be measured in excavation by cross-sections. 
 
 MASONRY. All masonry, ashlar, rubble, brick, concrete, etc., will be measured by 
 the cubic yard in place. Prices for masonry will include all required pointing. No 
 payment will be allowed for voids or openings. 
 
 BOLT HOLES. All holes drilled in rock or concrete or other masonry will be 
 measured by the running foot as drilled. 
 
 TIMBER IN PERMANENT CONSTRUCTION. Timber in permanent construction will 
 include all timber used in any part of the permanent construction ; unless otherwise 
 particularly specified, will be classed under the following heads : 
 Oak in Permanent Construction. 
 Pine in Permanent Construction. 
 Hemlock in Permanent Construction. 
 
APPENDIX. 141 
 
 EXTRACTS FROM TOPEKA (KANSAS) MELAN ARCH BRIDGE 
 
 SPECIFICATIONS. 
 
 By permission of EDWIN THACHER, M. Am. Soc. C. E. 
 PILING IN PERMANENT WORK. 
 
 Piling and lumber for coffer-dams to be sound white oak, yellow pine, or other 
 woods equally good for the purpose, the quality to be acceptable to the superintendent. 
 The piles shall be straight-grained, trimmed close, and have all bark taken off, and 
 shall be at least 10 inches in diameter at the small end and 14 inches in diameter at the 
 butt when sawed off. The heads shall be cut off squarely at right angles to the axis 
 of the pile, and all piles shall be fitted to and driven with a cast-iron head. The 
 piles shall be driven with a hammer weighing not less than two thousand two hundred 
 and fifty (2250) pounds, and until they do not move more than three-eighths (3/8) of an 
 inch under a blow of the hammer falling twenty-five (25) feet. No pile shall be driven 
 less than twenty-six (26) feet below low water, and if necessary to attain this minimum 
 depth jets shall be used in addition to hammer. The number and arrangement of the 
 piles for each foundation are shown on the plans, and must be carefully carried out by 
 the contractor. The piles shall be cut off at an elevation of about six (6) inches below 
 low water. A slight variation will be allowed, but no piles must be cut off at a higher 
 elevation. Inspection of piling and lumber, except at bridge site, shall be at con- 
 tractor's expense. 
 
 COFFER-DAMS. 
 
 After the bearing piles have been driven, a permanent coffer-dam, of the dimensions 
 marked on the plans, of Wakefield (or other equally satisfactory) sheet piling, shall be 
 used around each foundation. The earth inside thereof shall be excavated to the 
 depth shown on plans and replaced with concrete as hereinafter specified. During the 
 placing of the concrete the water shall be kept out of the coffer-dams unless the bottom 
 is so porous that it is impracticable in the opinion of the superintendent to do so in 
 which case some of the concrete may be placed in position by means of chutes under 
 the direction of the superintendent until the bottom is well calked, after which the 
 water shall be pumped out and the remaining concrete placed in position. The con- 
 tractor will be required to make the sides and ends of the coffer-dams water-tight, and 
 no leak through them will be considered sufficient cause to require any concrete to be 
 placed by means of chutes. 
 
 CENTERING. 
 
 The contractor shall build an unyielding falsework, or centering, of the form and 
 dimensions shown on the plans; particular care must be taken to drive the piles sup- 
 porting it to a solid bearing. The estimated load upon each of these piles is twenty 
 (20) tons. The contractor must, however, satisfy himself as to the load each pile will 
 have to bear, and as to its supporting power. In case of any settlement the contractor 
 shall take down and rebuild the centering and arch. The lagging shall be dressed on 
 both edges to a uniform size so that when laid it will present a smooth surface, and this 
 surface shall be built at the proper elevation to allow for settlement of arch, so that 
 when the centering is struck the arch ring will come to the elevations shown on plans. 
 
142 APPENDIX. 
 
 The top surface of the lagging shall be covered with W. Field's Building Paper of 
 medium weight, known as Double Saturated Water-proof Oiled Sheathing Paper (or 
 other equally good) to prevent the concrete from adhering thereto, No center shall 
 be struck until at least twenty-eight (28) days after the completion of the arch. Great 
 care shall be used in lowering the centers so as not to throw undue strains upon the 
 arches, nor shall any center be struck before ihe adjoining arch has been completed 
 for a sufficiently long time, in the opinion of the superintendent, to be uninjured 
 thereby. 
 
 NOTE. For the above reasons it is probable that the five centers will be in use at 
 the same time. 
 
 PORTLAND CEMENT. 
 
 The Portland'cement shall be a true Portland cement, made by calcining a proper 
 mixture of calcareous and clayey earths; and the contractor shall furnish one or more 
 certified statements of the chemical composition of the cement and of the raw materials 
 from which it is manufactured. Only one brand of Portland cement shall be used on 
 the work, except with permission of the superintendent, and it shall in no case contain 
 more than two (2) per cent of magnesia in any form. 
 
 The fineness of the cement shall be such that at least 98 per cent shall pass through 
 a standard brass cloth sieve of 74 meshes per linear inch, and at least 95 per cent shall 
 pass through a sieve of 100 meshes per linear inch. 
 
 Samples for testing may be taken from each and every barrel delivered as superin- 
 tendent may direct. Tensile tests will be made on specimens prepared and maintained, 
 until tested, at a temperature of not less than 60 degrees Fahrenheit. Each specimen 
 shall have an area of one square inch at the breaking section, and after being allowed 
 to harden in moist air for twenty-four hours shall be immersed and retained under 
 water until tested. 
 
 The sand used in preparing the test specimensshall be clean, sharp, crushed quartz, 
 retained on a sieve of 30 meshes per linear inch and passed through a sieve of 20 meshes 
 per linear inch, and shall be furnished by contractor. 
 
 No more than 23 to 27 per cent of water by weight Shall be used in preparing the 
 test specimens of neat cement, and in making the test specimens one of cement to three 
 of sand, no more than II or 12 per cent of water by weight shall be used. 
 
 Specimens prepared from neat cement shall after seven days develop a tensile 
 strength not less than 400 pounds per square inch. Specimens prepared from a 
 mixture of one part cement and three parts sand (parts by weight) shall after seven 
 days develop a tensile strength of not less than 140 pounds per square inch, and after 
 twenty-eight days not less than 200 pounds per square inch. Specimens prepared 
 from a mixture of one part cement and three parts sand (parts by weight) and immersed, 
 after twenty-four hours, in water to be maintained at 176 degrees Fahrenheit, shall 
 not swell nor crack,, and shall after seven days develop a tensile strength of not less 
 than 140 pounds per square inch. 
 
 Cement mixed neat with about 27 per cent of water, to form a stiff paste, shall, 
 after 30 minutes, be appreciably indented by the end of a wire one-twelfth inch in 
 diameter, loaded to weigh one-quarter pound. 
 
 Cement made into thin cakes on glass plates shall not cr^ck, scale, or \varp under 
 the following treatment: three pats shall be made and allowed to harden in moist air 
 at from 60 to 70 degrees Fahrenheit; one of these shall be subjected to water vapor at 
 176 degrees Fahr. for three hours, after which it shall be immersed in hot water for 
 forty-eight hours; another shall be placed in water at from 60 to 70 degrees Fahrenheit, 
 and the third shall be left in moist air. 
 
 Samples of one-to-two mortar and of concrete shall be made and tested from time 
 to time as directed by the superintendent. All cement shall be housed and kept dry 
 till wanted in the work. 
 
 Storage rooms and rooms and apparatus for the tests shall be furnished by the con- 
 tractor, and all tests shall be made entirely at his expense, and under the direction and 
 to the satisfaction of the superintendent. 
 
APPENDIX. 143 
 
 PORTLAND CEMENT CONCRETE. 
 
 The concrete shall be composed of clean, hard, broken limestone (or gravel with 
 irregular surfaces) and cement mortar in volumes as hereinafter described. The sand 
 shall be clean, sharp, Kansas River sand, washed entirely free from earth and loam. 
 If obtainable, a mixture of coarse and fine sand shall be used. Approved mixing 
 machines shall be used. These machines must be kept clean and no accumulations of 
 old mortar shall be allowed to form in them. The ingredients shall be placed in the 
 machine in a dry state and in the volumes specified and be thoroughly mixed, after 
 which clean water shall be added and the mixing continued until the wet mixture is 
 thorough and the mass uniform. No more w r ater shall be used than the concrete will 
 bear without quaking in ramming. The mixing must be done as rapidly as possible, 
 and the batch deposited in the work without delay, and before the cement begins to set. 
 Stone must be entirely free from earth and earthy surfaces. Thin splints or leaves of 
 stone, easily broken with fingers, will not be allowed to go into the work. The quality 
 of stone and the crushing must be acceptable to the superintendent. 
 
 The grades of concrete to be used are as follows (parts by volume): 
 
 For the arches: one part Portland cement, two parts sand, and four parts broken 
 stone (hazelnut size, from one-half inch to one inch), except for the exposed faces and 
 soffits of the arches, which[shall have at least one inch in thickness of mortar composed 
 of one part Portland cement and two parts sand. 
 
 For the piers, abutments, spandrel and wing walls: on the exposed surfaces for at 
 least one inch thick one part Portland cement and two parts sand; for the next seven 
 (7) inches one part Portland cement, two parts sand, and four parts broken stone of 
 hazelnut size. For the remaining portions- one part Portland cement, four parts sand, 
 and eight parts broken stone of size to pass through a three-inch ring; except such por- 
 tions of the interior of the piers and abutments as are above the top of the cornice, or 
 elevation 15.75 ft. above low water, which shall be composed of one part Portland 
 cement, three parts sand, and six parts broken stone which will pass through a two and 
 one-half inch ring. 
 
 No plastering of surfaces will be allowed nor any practice that will develop planes 
 or surfaces of demarkation other than those hereinafter described. Immediately after 
 the removal of any forms or centers, sand and cement shall be sifted on the surfaces 
 and the surfaces rubbed hard with a float as may be directed by the superintendent. 
 
 During warm and dry weather and whenever the superintendent shall direct, all 
 newly built concrete shall be kept well shaded from the sun and well sprinkled with 
 water at the surface for several days or until well set. 
 
 There must be no definite plane or surface of demarkation between the facing and 
 the concrete backing. The facing and the backing must be deposited in the same layer 
 and well rammed in place at the same time. 
 
 In connecting old concrete with new, in the planes hereafter described, the old 
 concrete shall be cleaned and roughened and soaked with water, and at the points of 
 contact a mortar composed of one part cement and two parts sand shall be used and 
 shall be laid in the same manner as specified for laying the facing. 
 
 NATURAL CEMENT CONCRETE. 
 
 The concrete around piles, to take the place of the earth excavated from the coffer- 
 dams, shall be composed of one part natural cement, equal to the best Fort Scott, Kas., 
 cement, three parts sand, and six parts of broken stone of the size to pass through a 
 three-inch ring. This concrete may be mixed by hand on platforms adjoining the 
 foundations and shoveled directly into the coffer-dams, care being taken to deposit it 
 in uniform layers of about six inches each and to carefully ram each layer. 
 
144 APPENDIX. 
 
 PIERS, ABUTMENTS, AND SPANDRELS. 
 
 All piers, abutments, spandrels, and wing walls shall be built in timber forms. 
 These forms shall be substantial and unyielding, of proper dimensions for the work 
 intended and closely pointed, and all surfaces that come in contact with the concrete 
 shall be smoothly dressed and well oiled with linseed oil to prevent the concrete from 
 adhering to them. That portion next to the exposed faces of the work need not be 
 oiled, but shall be covered with oiled paper, the same as that specified for the centers. 
 
 Molds, to form molding and panels, smoothly finished and well oiled with linseed 
 oil, shall be properly placed in the forms so that the finished work will appear as 
 shown on the plans. Extreme care must be used to place them in proper position 
 before placing any concrete or mortar in them. 
 
 CONTINUOUS WORK. 
 
 The following divisions shall constitute sections for continuous work, viz.: each 
 footing course of piers or abutments ; each pier or abutment from footing course to 
 cornice ; each pier or abutment from cornice to springing line of arch ; each spandrel 
 wall from keystone to pier or abutment ; each pier or abutment spandrel wall ; that 
 portion of the piers or abutments above springing line of arch shall be considered 
 part of the longitudinal sections of the arch previously described. 
 
 Each of the above sections shall be carried on continuously night and day if nec- 
 essary ; that is, each layer shall be well rammed in place before the previously de- 
 posited layer shall have time to partially set. 
 
 Care shall be taken to make the joints (for expansion) in each spandrel wall over 
 piers as indicated on the plans. 
 
 CONCRETE IN COFFER-DAMS. 
 
 The natural cement concrete in the coffer-dams shall extend from depths marked 
 on plans to one foot below low water. Upon this concrete the footing courses of piers 
 and abutments shall be founded. 
 
 The sheet piling of coffer-dams shall be cut off at least down to low-water mark, 
 neatly and evenly, by the contractor before the completion of the work. 
 
APPENDIX. H5 
 
 EXTRACTS FROM KATTE'S MASONRY SPECIFICATIONS. 
 
 By permission of WALTER KATTE, M. Am. Soc. C. E. 
 
 EXCAVATIONS will be classified under the following heads, viz.: earth, hardpan, 
 loose rock, solid rock, and excavation in water. 
 
 EARTH will include clay, sand, gravel, loam, decomposed rock and slate, stones 
 and boulders containing less than one cubic foot, and all other matters of an earthy 
 nature, however compact, excepting only " hardpan," as described below. 
 
 HARDPAN will consist of tough, indurated clay or cemented gravel which, in the 
 opinion of the Engineer, requires blasting for its removal. 
 
 LOOSE ROCK. All boulders and detached masses of rock measuring over one (i') 
 cubic foot in bulk, and less than one (i) cubic yard ; also all slate, shale, soft friable 
 sandstone and soapstone, and all other materials excepting rock, solid ledge, and 
 those described above ; also stratified rock in layers of not exceeding eight (8") inches 
 in thickness, when separated by strata of clay, and which, in- the judgment of the 
 Engineer, may be removed without blasting, although blasting may occasionally be 
 resorted to. 
 
 SOLID ROCK will include all rock found in ledges, or masses of more than one (i) 
 cubic yard, which, in the judgment of the Engineer, may be best removed by blasting , 
 with the exception of stratified rocks described under the head of Loose Rock. In rock 
 excavations the " bottom " must in all cases be taken down truly to sub-grade ; and 
 when so ordered by the Engineer ditches must be formed at the foot of the slope. 
 
 The contract price for excavation will apply to pits required for foundations of 
 masonry when water is not encountered, and the price for 
 
 EXCAVATION IN WATER will only apply to foundation pits under water and deep- 
 ening of channels in running water ; it must cover all classes of material, and include 
 drainage, bailing, pumping, and all materials and labor connected with such excava- 
 tions ; also the necessary dressing of the rock. 
 
 CEMENT must be of the best quality of freshly burned and ground hydraulic 
 cement, and be equal in quality to the best brands of Cement. It 
 
 will be subject to test made by the Engineer or his appointed inspector, and must 
 stand a proof tensile test of fifty (50) pounds per square inch of sectional area on 
 specimens allowed a set of thirty (30) minutes in air and twenty-four (24; hours under 
 water. 
 
 MORTAR will in all cases be made of one part in bulk of the best hydraulic cement 
 to two parts in bulk of clean, sharp sand, well and thoroughly mixed together in a 
 clean box of boards, before the addition of the water, and must be used immediately 
 after being mixed. No mortar left over night will, under any pretext, be allowed to 
 be used. The sand and cement used will at all times be subject to inspection, test, 
 acceptance, or rejection by the Engineer. 
 
 CONCRETE. Concrete shall be composed of fragments of hard, sound, and accept- 
 able stone, broken to a size that will pass through a two (2") inch ring in any direction, 
 thoroughly clean and free from mud, dust, dirt, or any earthy admixture whatever ; 
 mixed in the proportion of two (2) parts in bulk of the broken stone to one (i) part of 
 fresh-made cement mortar of the quality herein described ; and is to be quickly laid in 
 sections and in layers not exceeding nine (9) inches in thickness, and to be thoroughly 
 rammed until the mortar Hushes to the surface ; it shall be allowed at least twelve (12) 
 hours to " set" before any work is laid on it. 
 
APPENDIX. 
 
 FOUNDATIONS. 
 
 GENERAL DESCRIPTION. Foundations for masonry shall be excavated to such 
 depths as may be necessary to secure a solid bearing for the masonry, of which the 
 Engineer shall be the judge. The materials excavated will be classified and paid for. 
 as provided for in these specifications, under the general head of Excavations ; and in 
 case of foundations in rock, the rock must be excavated to such depth and in such 
 form as may be required by the Engineer, and must be dressed level to receive the 
 foundation course. 
 
 When a safe and solid foundation for masonry cannot be found at a reasonable depth 
 (to be judged of by the Engineer), there will be prepared by the contractor such artifi- 
 cial foundations as the Engineer may direct. All materials taken from the excavations 
 for foundations, if of proper quality, shall be deposited in the contiguous embankment; 
 but any material unfit for such purpose shall be deposited outside the roadway, or in 
 such place as the Engineer shall direct, and so that it shall not interfere with any 
 drain or watercourse. 
 
 TIMBER. Timber foundations when required shall be such as the Engineer may by 
 drawings or otherwise prescribe, and will be paid for by the one thousand feet, board 
 measure. The price, covering cost of material, framing and putting in place, and all 
 wrought- and cast-iron work ordered by the Engineer, will be paid for per pound, the 
 price including cost of material, manufacture, and placing in the work. 
 
 PILING. All timber used in foundations or foundation piling shall be of young, 
 sound, and thrifty white oak, yellow pine, or other timber equally good for the purpose, 
 acceptable to the Engineer. Piles must be at least eight (8") inches in diameter at the 
 small end and twelve (12") inches in diameter at the butt when sawn off; they must be 
 perfectly straight and be trimmed close, and have the bark stripped off before they are 
 driven. They must be driven into hard bottom until they do not move more than one- 
 half inch under the blow of a hammer weighing two thousand (2000) pounds, falling 
 twenty-five (25') feet at the last blow. They must be driven vertically and at the regular 
 distances apart from centers, transversely and longitudinally, as required by the plans 
 or directions of the Engineer; they must be cut off squarely at the butt and be well 
 sharpened to a point, and when necessary, in the opinion of the Engineer, shall be shod 
 with iron and the heads bound with iron hoops, of such dimensions as he may direct, 
 which will be paid for the same as other iron work used in foundations. 
 
 The necessary length of piles shall be ascertained by driving test piles in different 
 parts of the localities in which they are to be used; and in case a pile shall not prove 
 long enough to reach " hard bottom " it shall be sawed off square, and a hole two (2") 
 inches in diameter be bored into its head twelve (12") inches deep; into this hole a 
 circular white-oak trenail twenty three (23") inches in length shall be well driven, and 
 another pile similarly squared and bored, and of as large a diameter at the small end 
 as can be procured, shall be placed upon the lower pile, brought to its proper position, 
 and driven as before directed. All piles, when thus driven to the required depth, are to 
 be cut off truly square and horizontal at the proper height given by the Engineer, and 
 only the actual number of lineal feet of the piles left for use in the foundations after 
 being sawn off will be paid for. 
 
 COFFER-DAMS. Where coffer-dams are, in the opinion of the Engineer, required for 
 foundations the prices provided in the contract for timber, piles, and iron in founda- 
 tions will be allowed for the material and work on same, which is understood as cover- 
 ing all risks from high water or otherwise, draining, bailing, pumping, and all materials 
 connected with the coffer-dams. Sheet piling will be classed as plank in foundations, 
 and will be paid for per one thousand (1000') feet board measure if left in the ground. 
 
 TIMBER. 
 
 All timber must be sound, straight-grained, and free from sap, loose or rotten knots, 
 wind shakes, or any other defect that would impair its strength or durability; it must 
 be sawed (or hewed) perfectly straight and to exact dimensions, with full corners and 
 square edges; all framing must be done in a thoroughly workmanlike manner, and 
 both material and workmanship will be subject to the inspection and acceptance of the 
 Engineer. 
 
APPENDIX. 147 
 
 SPECIFICATIONS FOR STEEL COFFER-DAM. 
 
 DESIGN. The shell shall be made of elliptical shape for ordinary piers and circular 
 for pivot piers. It shall be made not less than four feet larger than footing of pier 
 in plan, to allo;v for variation in position during sinking. 
 
 The plates used shall be as large as can be handled with ease in the shop, during 
 shipment, and during erection. 
 
 The splices may be either lap or butt joints, provided a good tight job will result, 
 and the rivets must be spaced according to bcilermaker's rules. 
 
 The joint may be made tight by calking or by the use of a calking strip, but in 
 either event the result must be guaranteed. 
 
 The shell must be stiffened by horizontal stiffening angles, girders, or trussing, to 
 resist deformation during the placing and to resist both the quiescent and a maximum 
 unbalanced earth or water pressure, or a wind pressure. 
 
 The bottom plates shall be re-enforced with narrow plates inside and outside, to 
 form a wedge-shaped cutting edge; and when there is rock or hard bottom the plates 
 shall be cut to conform to its contour as nearly as possible. 
 
 The top shall be properly stiffened, and if necessary provided with connection holes 
 for additional sections. 
 
 The factor for safety shall in no case be less than four, and in case the shell will be 
 subject to shock, not less than six. 
 
 No metal of a less thickness than 1/4 inch shall be used for temporary work, nor less 
 than 3/8 inch for permanent work in fresh water or 1/2 inch in salt water. 
 
 MATERIAL. The entire shell shall be constructed of the grade of steel known as 
 soft medium, except rivets, which shall be of bridge quality of iron. 
 
 The steel may be made either by the Bessemer or open-hearth process, and the 
 phosphorus shall never exceed 0.08 per cent. 
 
 Soft medium steel shall have an ultimate strength of from 55,000 1065,000 pounds 
 per square inch, as determined from standard rest pieces ; an elastic limit of not less 
 than one-half the ultimate strength ; an elongation of not less than 25 per cent in 8 
 inches , and a reduction of area at fracture of not less than 50 per cent. 
 
 Samples to bend cold 180 degrees to a diameter equal to the thickness of the 
 sample, without crack or flaw on the outside of the bent portion. 
 
 ERECTION. The erection must be done in a first-class manner, and all rivets must 
 have full heads. The shell shall be placed in position within one-half the distance 
 allowed for error in the design of the coffer-dam. Only a reasonable variation will be 
 allowed for difference in level. 
 
 PAINTING. All the metal work shall be thoroughly cleaned of rust or scale at the 
 shops and coated thoroughly with hot asphaltum. 
 
 Before erection, in the field, it shall be given a second coating of hot asphaltum. 
 
 SEALING. When in position on the bottom, if the coffer-dam has not been sunk 
 through impervious strata, it shall be sealed by concreting around the circumference 
 inside with concrete passed through a tube. 
 
 REMOVAL. Should the coffer-dam not form a part of the permanent foundation 
 it shall be taken apart, at the joints designed for ihe purpose, and carefully removed 
 in such a manner as not to injure the foundation, and so as to be used again if required. 
 
I4 APPENDIX. 
 
 HEALD & SISCO STANDARD IRON HORIZONTAL CENTRIFUGAL PUMPS, 
 
 
 
 Horse-power 
 
 
 
 
 
 
 
 No. 
 
 Capacity in 
 Gallons per 
 Minute. 
 
 required for 
 Each Foot 
 of Lift. 
 Minimum 
 
 Diameter 
 and Face 
 of Pulley 
 in Inches. 
 
 Floor 
 Space 
 required, 
 in Inches. 
 
 Shipping- 
 Weight. 
 Pounds. 
 
 Price of 
 Pump, 
 Oilers and 
 Wrench. 
 
 Price of 
 Pump and 
 Primer. 
 
 No. 
 
 
 
 Quantity. 
 
 
 
 
 
 
 
 It 
 
 50 to 70 
 
 .024 
 
 6X6 
 
 17 X 30 
 
 168 
 
 $45 
 
 $55 
 
 I* 
 
 If 
 
 75 to 100 
 
 037 
 
 7X8 
 
 21 X 33 
 
 232 
 
 60 
 
 70 
 
 If 
 
 2 
 
 no to 150 
 
 054 
 
 8 X 8 
 
 23 X 37 
 
 306 
 
 75 
 
 90 
 
 2 
 
 2| 
 
 175 to 250 
 
 .086 
 
 8X8 
 
 24 X 38 
 
 348 
 
 90 
 
 105 
 
 at 
 
 3 
 
 250 to 350 
 
 .124 
 
 8X8 
 
 25 X 39 
 
 400 
 
 no 
 
 130 
 
 3 
 
 4 
 
 450 to 600 
 
 .223 
 
 10 X 10 
 
 30 X 40 
 
 545 
 
 130 
 
 155 
 
 4 
 
 5 
 
 750 to 900 
 
 372 
 
 15 X 12 
 
 34 X 54 
 
 826 
 
 165 
 
 195 
 
 5 
 
 6 
 
 1000 to 1400 
 
 .496 
 
 15 X 12 
 
 37 X 55 
 
 965 
 
 200 
 
 240 
 
 6 
 
 8 
 
 I7OO to 22OO 
 
 .844 
 
 2O X T2 
 
 45 X 63 
 
 1500 
 
 310 
 
 375 
 
 8 
 
 10 
 
 22OO to 3OOO 
 
 1.093 
 
 24 X 12 
 
 5i X 71 
 
 2170 
 
 395 
 
 470 
 
 10 
 
 12 
 
 3000 to 4000 
 
 1.49 
 
 30 X 14 
 
 62 X 78 
 
 3050 
 
 500 
 
 
 12 
 
 15 
 
 4800 to 6000 
 
 2.38 
 
 40 X 15 
 
 77 X So 
 
 7100 
 
 850 
 
 
 15 
 
 is 
 
 4800 to 6000 
 
 2.38 
 
 30 x 15 
 
 60 X 68 
 
 3150 
 
 710 
 
 
 15 
 
 18 
 
 7500 to loooo 
 
 3-73 
 
 40 X 15 
 
 93 X 103 
 
 9000 
 
 1300 
 
 
 18 
 
 *i8 
 
 7500 to 10000 
 
 3-73 
 
 30 X 16 
 
 62 X 70 
 
 3500 
 
 1150 
 
 
 18 
 
 22 
 
 I2OOO tO I4OOO 
 
 5-96 
 
 48 X 20 
 
 126 X 130 
 
 12000 
 
 
 
 22 
 
 * Refers to low-lift pump. 
 
 The number of pump is also diameter of discharge opening in inches. Where more 
 than 25 feet of discharge pipe is attached to pump, use one or two sizes larger than 
 pump discharge. 
 
 For No. 12 and larger sizes a foot valve or flap valve and ejector for priming is 
 recommended. 
 
 LIST OF HEALD & SISCO HYDRAULIC DREDGING AND SAND PUMPS. 
 
 Num- 
 ber of 
 Pump. 
 
 Diameter 
 Suction 
 and Dis- 
 charge 
 Open- 
 ings. 
 
 Cubic 
 Yards of 
 Material 
 they will 
 Raise per 
 
 Hour 
 
 Horse- 
 power 
 recom- 
 mended 
 for 10- 
 Foot 
 
 Diameter 
 and Face 
 of Pulley. 
 
 Floor Space 
 Required. 
 Inches, 
 
 Shipping 
 Weight. 
 Pounds. 
 
 Will 
 Pass 
 Solids, 
 Diameter. 
 Inches 
 
 Price of Pump 
 Complete, with 
 Suction and 
 Discharge 
 Elbows, Flap 
 Valve and 
 
 Num- 
 ber 
 of 
 Pump. 
 
 
 Inches. 
 
 
 Lift. 
 
 
 
 
 
 Ejector. 
 
 
 4 
 
 4 
 
 30 to 50 
 
 6 
 
 12 X 12 
 
 40 x 31 
 
 800 
 
 2 
 
 $2IO 
 
 4 
 
 6 
 
 6 
 
 60 to 80 
 
 12 
 
 20 X 12 
 
 68 X 40 
 
 I7OO 
 
 4i 
 
 3OO 
 
 6 
 
 8 
 
 8 
 
 125 to 150 
 
 22 
 
 24 X 14 
 
 72 x 48 
 
 3400 
 
 6 
 
 475 
 
 8 
 
 10 
 
 10 
 
 2OO tO 3OO 
 
 35 
 
 30 x 15 
 
 94 X 54 
 
 4200 
 
 8 
 
 600 
 
 10 
 
 12 
 
 12 
 
 300 to 375 
 
 45 
 
 36 X 20 
 
 114 X 66 
 
 9OOO 
 
 10 
 
 850 
 
 12 
 
 15 
 
 15 
 
 400 to 500 
 
 75 
 
 42 X 24 
 
 154 X 78 
 
 I2OOO 
 
 10 
 
 1450 
 
 15 
 
 18 
 20 
 
 18 
 2O 
 
 500 to 700 
 
 125 
 
 48 X 30 
 
 160 X 80 
 
 13500 
 
 IO 
 
 1900 
 
 18 
 20 
 
 22 
 
 22 
 
 
 
 
 
 
 
 .... 
 
 22 
 
APPENDIX. 
 
 149 
 
 NUMBER OF REVOLUTIONS AT WHICH PUMPS SHOULD RUN TO RAISE 
 WATER TO DIFFERENT HEIGHTS. 
 
 No. 
 
 5 Feet. 
 
 10 Feet. 
 
 15 Feet. 
 
 20 Feet. 
 
 25 Feet. 
 
 30 Feet. 
 
 35 Feet. 
 
 40 Feet. 
 
 I* 
 
 428 
 
 604 
 
 739 
 
 854 
 
 955 
 
 1045 
 
 H3I 
 
 1208 
 
 If 
 
 348 
 
 491 
 
 60 1 
 
 695 
 
 777 
 
 850 
 
 920 
 
 982 
 
 2 
 
 3O2 
 
 426 
 
 522 
 
 60 3 
 
 674 
 
 737 
 
 798 
 
 8 5 2 
 
 2* 
 
 302 
 
 426 
 
 522 
 
 60 3 
 
 674 
 
 737 
 
 798 
 
 8 5 2 
 
 3 
 
 302 
 
 426 
 
 522 
 
 60 3 
 
 674 
 
 737 
 
 798 
 
 8 5 2 
 
 4 
 
 285 
 
 402 
 
 493 
 
 569 
 
 637 
 
 697 
 
 754 
 
 805 
 
 5 
 
 256 
 
 362 
 
 443 
 
 512 
 
 572 
 
 626 
 
 678 
 
 724 
 
 6 
 
 214 
 
 302 
 
 368 
 
 427 
 
 478 
 
 523 
 
 566 
 
 604 
 
 8 
 
 183 
 
 259 
 
 317 
 
 366 
 
 409 
 
 448 
 
 485 
 
 517 
 
 10 
 
 168 
 
 238 
 
 291 
 
 336 
 
 376 
 
 411 
 
 445 
 
 475 
 
 12 
 
 133 
 
 188 
 
 230 
 
 266 
 
 298 
 
 326 
 
 352 
 
 376 
 
 15 
 
 105 
 
 148 
 
 181 
 
 2OQ 
 
 234 
 
 256 
 
 277 
 
 295 
 
 *I5 
 
 151 
 
 213 
 
 261 
 
 301 
 
 337 
 
 369 
 
 399 
 
 426 
 
 18 
 
 105 
 
 148 
 
 181 
 
 209 
 
 234 
 
 256 
 
 277 
 
 295 
 
 *iS 
 
 151 
 
 213 
 
 261 
 
 301 
 
 337 
 
 369 
 
 399 
 
 426 
 
 * Refers to low^lift pumps. 
 
 Above table gives correct speed of pumps as employed under usual conditions of 
 pumping. If water must be forced through a number of bends and elbows, or a great 
 length of piping, the above speed must be somewhat increased. 
 
 Use large pipes and easy bends wherever practicable, as they save power. 
 
 TABLE OF SIZES, LIDGERWOOD SINGLE-CYLINDER, SINGLE-DRUM 
 
 HOISTING-ENGINES. 
 
 d 
 u 
 
 Dimensions of 
 Cylinder. 
 
 3 
 w <u i 
 
 ij-* 
 
 Dimensions of 
 Hoisting-drum. 
 
 Dimensions of 
 Bed-plate. 
 
 Dimensions of Boiler 
 
 'E.-^ 
 
 
 
 
 - o\J 
 
 'v c 
 
 >, 
 
 >> 
 
 
 
 
 
 _ 
 
 
 f.% 
 
 0^ 
 
 B 
 
 X 
 
 Diameter. 
 Inches. 
 
 . ti 
 
 ji-g 
 
 2JS 
 
 p 
 
 11 
 
 Diam Bod 
 between 
 Flanges. 
 Inches. 
 
 So^jS <> 
 
 Q 
 
 Width. 
 Inches. 
 
 tl 
 
 Diameter 
 Shell. 
 Inches. 
 
 Height She 
 Inches. 
 
 Number of 
 2-inch 
 Tubes. 
 
 Estimated 
 Weight C 
 Lbs 
 
 4 
 
 5 
 
 8 
 
 I2OO 
 
 1000 
 
 ,0 
 
 20 
 
 22 
 
 38 
 
 60 
 
 28 
 
 63 
 
 40 
 
 3550 
 
 6 
 
 63- 
 
 8 
 
 I5OO 
 
 1250 
 
 10 
 
 20 
 
 22 38 
 
 60 
 
 28 
 
 69 
 
 40 
 
 3950 
 
 8 
 
 6|- 
 
 IO 
 
 1750 
 
 1500! 12 
 
 20 
 
 24 41 
 
 73 
 
 30 
 
 72 
 
 44 
 
 4850 
 
 IO 
 
 7 
 
 10 
 
 2500 
 
 i8oo ! 12 
 
 2O 
 
 24 41 
 
 73 
 
 32 
 
 75 
 
 48 
 
 5050 
 
 n 
 
 7 
 
 10 
 
 2500 
 
 2000 14 
 
 22 
 
 26 
 
 45 
 
 73 
 
 34 
 
 78 
 
 52 
 
 5350 
 
 12} 
 
 81 
 
 IO 
 
 4000 
 
 2500; 14 
 
 23 
 
 29 
 
 47 
 
 73 
 
 36 
 
 75 
 
 57 
 
 6550 
 
 15 
 
 
 IO 
 
 4OOO 
 
 28OO 14 
 
 23 
 
 29 
 
 47 
 
 73 
 
 36 
 
 81 
 
 57 
 
 6750 
 
 20 
 
 8* 
 
 12 
 
 6OOO 
 
 4000 1 6 
 
 26 
 
 33 54 
 
 84 
 
 40 
 
 84 
 
 80 
 
 8500 
 
 25 
 
 IO 
 
 12 
 
 8000 
 
 5000! 16 
 
 26 
 
 33 
 
 54 
 
 84 
 
 42 
 
 90 
 
 88 
 
 9500 
 
 
 
 
 
 
 
 
 
 
 
 
 
ISO 
 
 APPENDIX. 
 
 TABLE OF SIZES, LIDGERWOOD DOUBLE-CYLINDER, DOUBLE-DRUM 
 
 HOISTING-ENGINES. 
 
 a 
 aj 
 
 Dimensions of 
 Cylinders. 
 
 Dimensions of 
 Hoisting-drums 
 
 11 
 
 w be 
 tf|* 
 
 Dimensions of Boiler. 
 
 Dimensions of 
 Bed-plate. 
 
 .9- 
 
 ^ u 
 
 & 
 
 
 
 o o(/> 
 
 
 
 
 ]?= 
 
 g 
 
 
 
 
 
 ~ <u ** 
 
 ujk g^ 
 
 
 
 Num- 
 
 
 
 U> 
 
 rt a 
 
 3 
 
 Diam. 
 
 Stroke. 
 
 Diam. 
 
 Length. 
 
 "bVbflw 
 
 "re^ 1 B.y 
 
 Diam. 
 
 Height. 
 
 ber of 
 
 Width. 
 
 Length 
 
 
 E CO 
 
 Inches. 
 
 Inches. 
 
 Inches. 
 
 Inches. 
 
 jj > 
 
 -<<-i 2 .2 
 
 Inches. 
 
 Inches. 
 
 2-inch 
 
 Inches. 
 
 Inches. 
 
 
 E D 
 
 
 
 
 
 jgj</3< 
 
 (/} 
 
 
 
 Tubes. 
 
 
 
 a*U 
 
 8 
 
 5 
 
 8 
 
 12 
 
 22 
 
 2OOO 
 
 1500 
 
 32 
 
 75 
 
 48 
 
 47 
 
 80 
 
 650-) 
 
 12 
 
 6} 
 
 8 
 
 14 
 
 22 
 
 3OOO 
 
 2000 
 
 36 
 
 75 
 
 57 
 
 50 
 
 86 
 
 8OOO 
 
 16 
 
 
 10 
 
 14 
 
 26 
 
 4OOO 
 
 2800 
 
 38 
 
 81 
 
 68 
 
 54 
 
 89 
 
 9000 
 
 20 
 
 7 
 
 10 
 
 14 
 
 26 
 
 5000 
 
 3500 
 
 40 
 
 84 
 
 80 
 
 54 
 
 89 
 
 9550 
 
 30 
 
 H 
 
 IO 
 
 14 
 
 27 
 
 8000 
 
 5OOO 
 
 42 
 
 90 
 
 88 
 
 57 
 
 94 
 
 II400 
 
 40 
 
 81 
 
 12 
 
 16 
 
 32 
 
 IOOOO 
 
 8000 
 
 50 
 
 IO2 
 
 124 
 
 70 
 
 117 
 
 2IOOO 
 
 50 
 
 10 
 
 12 
 
 16 
 
 32 
 
 I2OOO 
 
 IOOOO 
 
 53 
 
 IO2 
 
 150 
 
 70 
 
 117 
 
 22000 
 
INDEX. 
 
 Aa river, Russia, 83 
 Ancient methods of 
 
 Founding, I, 3, 4, 5 
 
 Pile driving, 5, 40, 41 
 
 Pumping, 92, 93 
 
 Sheet piling, 6, 7 
 
 Anchoring, coffer-dam, 30, 32, 33, 87 
 Approval, War Dep't, 120 
 Arkansas river, 20, 70 
 Architectural design, piers, 125, 127, 131 
 Arch bridge 
 
 Center, 141 
 
 Hutcheson, Scotland, 6 
 
 Largest, 3 
 
 Melan, Topeka, 78, 119, 141, 142 
 
 Roman, I 
 
 Shuster, Persia, I 
 
 Topeka, Kansas, 78, 119, 141, 142 
 
 Trezzo, I 
 
 Asphalt for leaks, 65 
 Bamboo casings, 4 
 Bank protection 
 
 Japanese, 4 
 
 Mississippi, 4 
 Bascule pump, 92 
 Batter of piers, 125 
 Bear river, Canada, 83 
 Bearing 
 
 Piles, 106. 146 
 
 Power of piles. 49 
 Blasting, 33, 73, 89 
 Boiler riveting, 80, 82, 147 
 Bolts, 7, 57, 139 
 
 See Drift-bolts 
 Borings 
 
 Auger, Pierce, 121 
 
 Casing for, 121 
 
 Clamp for driving tube, 122 
 
 Core removal, 122 
 
 Cutting shoe for pipe, 122 
 
 Drills foi , 121 
 
 Driving pipe for, 122 
 
 Extensive, 121 
 
 Hand drills for, 121 
 
 Jars for, 121 
 
 Maul for driving pipe, 122 
 
 Borings Continued. 
 
 Obstructions to, 121 
 
 Pebble-tongs, 124 
 
 Pump, sand, 121, 122 
 
 Removal of core, 122 
 
 Rope knives, 121 
 
 Rope spears, 121 
 
 Sand pump, 121, 122 
 
 Screw, adjusting, 121 
 
 Spears, rope, 121 
 
 Temper screw, 121 
 
 Test, 121 
 
 Tongs, pebble, 124 
 
 Tripod for, 121 
 
 Well-driller, 121 
 Bottom 
 
 Clay, 38, 57, 60, 73, 77 
 
 Drift in sand, 18 
 
 Gravel, 6, 16, 20, 57,60, 64, 66, 74, 106, 133 
 
 Hard clay, 10, 12, 77, 106 
 
 Mud, 17, 38, 60, 62, 77, 106 
 
 Open (porous), 16, 28 
 
 Overlaid. See Rock 
 
 Porous, 16, 28, 141 
 
 Quicksand, 67 
 
 Rock, i, 20, 24, 25, 26, 28, 29. 30, 32, 33, 
 36, 38, 39, 57, 62, 66, 72, 74, 77. 86, 106 
 
 Rock, overlaid, 16, 20, 24 25, 29, 33, 36, 
 38, 57, 66, 72, 74, 77, 106 
 
 Sand, 62, 64, 68, 77, 78, 106 
 
 Sand and drift, 18 
 
 Sand and shells, 77 
 
 Shale, 60 
 
 Shells in sand, 77 
 
 Silt, 33 
 
 Soapstone, 20 
 
 Soundings, 86, 120, 121 
 
 Uneven, 17, 32, 33, 36, 62, 76, 106 
 Boxing in leaks, 32, 39, 60 
 Box pump, 93 
 
 Bras d'Or river, Canada, 82 
 Brace rods, 30, 38, 67, 134 
 Braces, 7, 30, 33, 38, 39, 56, 64, 67, 76 80, 
 
 83, 84, 135 
 
 Bridge location, 120 
 Bridge cost, economic, 124, 125 
 
152 
 
 INDEX. 
 
 Bridges referred to 
 
 Ann Arbor, 59 
 
 Arnprior, 18 
 
 Arthur Kill, 38, 60 
 
 Baltimore, N. Ave., 118 
 
 Blackfriars, London, 4 
 
 Boucicault France, 109 
 
 Buda-Pesth, 8, 28, 50, 53 
 
 Caesar's, over Rhine, 5, 40 
 
 Charlestown, Boston, 53, 63 
 
 Chattanooga, Walnut St., 66, 99, 107 
 
 Coteau, 39 
 
 Cumberland, Md., 67 
 
 Fair Haven, 48 
 
 Forth, Scotland, 86, 99, 107 
 
 Fort Madison, la., 20 
 
 Gadsden, Ala., 74 
 
 Harvard, Boston, no 
 
 Harlem ship-canal, 36 
 
 Harper's Ferry, 63 
 
 Hawkesbury, Australia, 80 
 
 Hutcheson, Glasgow, 6, 50, 57 
 
 Little Rock, Ark., 70, in 
 
 Melbourne, Australia, 33 
 
 Momence, Illinois, 62 
 
 Neuilly, France, 92 
 
 Omaha, Nebraska, 127 
 
 Orleans, France, 40, 92, 93 
 
 Philadelphia, Walnut St., 24 
 
 Phila. & Reading R. R., 74 
 
 Putney, England, 77 
 
 Red River, in 
 
 Riga-Orel, Russia, 83 
 
 Rochester, Court St., 117 
 
 Saumur, France, 41 
 
 Shuster, Persia, i 
 
 Topeka, Kansas, 78, 119 
 
 Trajan's, 40 
 
 Tulsa, 20 
 
 Victoria, Canada, 83 
 
 Westminster, London, 4 
 Bucket-wheel pump, 92 
 Bucket for concrete, 36, 39, no 
 Bull-wheel pile driver, 41 
 Bulkhead, 30 
 Cableway 
 
 Capacity of, 117 
 
 Carriage for, 117 
 
 Span of, 117, 118 
 
 Use of, 117 
 Caisson 
 
 Open, 3, 4, 13 
 
 Pneumatic, 5 
 
 Water-tight, 74 
 Calking 
 
 Cylinders, 82 
 
 Joints, 20, 36, 147 
 Canal 
 
 Chicago drainage, 117" 
 
 Harlem ship, 36 
 
 Illinois & Miss.. 113 
 
 Keokuk, la., 30 
 
 N. Y. State, 45, 50 
 
 Candle wick for leaks, 20 
 Cane stalks for leaks, 28 
 Canvas sheet, 30, 31, 32, 33, 35 
 Capacity of 
 
 Cableway, 117 
 
 Dredge, 101, 102, 103, 135, 148 
 
 Pumps, 77, 78, 93, 94, 99, 101, 135, 148 
 Carriage for cableway, 117 
 Casing 
 
 Bamboo, 4 
 
 Boring, 121 
 
 Timber, 5 
 Cement (see Concrete) 
 
 Defective, 114, 136 
 
 Laitance of, 109 
 
 Mortar, 136, 143, 145 
 
 Natural, in, 136, 143, 145 
 
 Portland, 113, 115, 116, 142 
 
 Quality of, 114, 136, 142, 145 
 
 Specifications, 136, 142, 145 
 
 Tests of, 115, 136. 142, 145 
 Center for arch, 141 
 Centrifugal pump, see Pump 
 Chamber, width of, 56 
 Chamber, see puddle 
 Changes, 139 
 Channel ' 
 
 Establishing new, 3 
 
 Fixed place for, 120 
 
 Requirements of Gov't, 120 
 Chapelet pump. 92, 93 
 Charles river, Boston, 63, no 
 Circular 
 
 Coffer-dam, see Coffer-dam 
 
 Pier of granite, 86 
 
 Shell for pier, see cylinder 
 Clam-shell dredge, 102 
 Clamp for 
 
 Coffer-dam, 38 
 
 Pile-driver, 43 
 
 Pipe, 122 
 
 Sheet piles, 57 
 
 Classification of excavation, 135, 145 
 Clay, see Bottom 
 Clay puddle, see Puddle 
 Clearance in coffer-dam, 74, 147 
 Clyde river, Scotland, 6 
 Coffer-dam 
 
 Anchoring, 30, 32, 33, 37 
 
 Calculation of, 54, 56, 84 
 
 Canvas and plank, 30, 32, 33, 35 
 
 Circular, 20, 24, 87, 147 
 
 Clearance in, 74. 147 
 
 Cost of, 61, 76, 77 
 
 Crib type, 14, 15, 17, 18, 20, 26, 32, 33, 
 36. 38, 39, 72 
 
 Damaged, 24, 32, 35, 60, 66, 76 
 
 Decking for, 134 
 
 Definition of, 13 
 
 Deposit in, 134 
 
 Earth bank type, 5, 13, 14, 26 
 
 Economy in, 26 
 
 Erecting steel, 147 
 
Of THK ' 
 
 UNIVERSITY 
 
 INDEX. 
 
 153 
 
 Coffer-dam Continued. 
 
 Failure of, 16, 24, 28, 30, 32, 60 
 
 Floating type, 74 
 
 Frame for, 30, 35, 59, 66, 67, 75 
 
 Grillage type, 20, 24 
 
 Half-tide, 89 
 
 Largest recorded, 8 
 
 Location of, 86, 87 
 
 Metal, type of, 83, 86, 147 
 
 Movable, 20, 33, 74, 75, -76 
 
 Moving, time required, 76 
 
 Origin of, 3, 5 
 
 Pivot pier, 20, 36, 38, 39, 147 
 
 Polygonal type, 36, 38, 39 
 
 Price for, 139 
 
 Protection, 26, 33 
 
 Puddle, pressure on, 54 
 
 Puddle for, see Puddle 
 
 Removal of, 120, 33, 74, 134, 147 
 
 Removing piers by, 72, 74 
 
 Robinson, circular, 24 
 
 Sheet pile type, 6, 8, 9, 24, 26, 59, 60, 61, 
 62, 63, 64, 65, 134 
 
 Sinking with stone, 20, 76 
 
 Specifications for, 6, 134, 141, 146, 147 
 
 Splicing in height, 67, 147 
 
 Tarpaulin and plank, 30, 32, 33, 35 
 
 Tidewater type, 8, 53, 63, 86 
 
 Wakefield piling, 14, 20, 53, 61, 62, 63, 
 64, 141 
 
 Water pressure on, 54, 56 
 
 Width of chambers, 56 
 Compartments, water-tight, 76 
 Completion of work, 139 
 Composition of concrete, see Concrete 
 Compound sheet piles, 52, 53, 61, 66 
 Concrete 
 
 Ancient use of, 2, 4 
 
 Bucket for depositing, 36, 39, no 
 
 Composition of, 107, no, in, 116, 138, 
 
 143, M5 
 Cost of, 117 
 
 Depositing, rate of, 115 
 Facing for, 72, in, 114, 143 
 Forms for, in, 113, 115, 141, 142, 144 
 Foundation of, 18, 24, 36, 60, 61, 63, 67, 
 
 72, 107, 108, 116, 117, 138, 143, 144, 
 
 146 
 
 Laitance, 109 
 
 Laying, rules for, 113, 138, 143, 145 
 Layers, proper thickness, 109, 113, 138, 
 
 143, 144, 145 
 
 Leveling course, 107, 117 
 Louisville cement used, ill 
 Monolithic construction, 72, in, 112, 113, 
 
 143 
 
 Oil paper on forms, 142 
 Piers of, 72, in, 143, 144 
 Pier filling, 80, 82, 143 
 Portland cement used, 72, 113, 115, 116, 
 
 143 
 
 Proportions of, 67, 72, 107, no, in, 116, 
 138, 143, 145 
 
 Concrete Continued. 
 Puddle of, 38. 78, 87 
 Rate of deposit, 115, 143, 144, 145 
 Rules for laying, 113, 138, 143, 144, 145 
 Sacked for placing, 107 
 Sand for, in, 115, 136, 143, 145 
 Setting time, no, 114, 143, 144, 145 
 Stone for, in, 115, 143, 145 
 Tube for depositing, 108, no 
 Under water, 36, 39, 107, 108, 109, no, 142 
 Water, amount for, 113, 114, 143 
 Wells in. 114 
 
 Coosa river, Ala., 74, no, 117 
 Coping, 125, 127, 129, 137 
 Corbel course, 127, 129 
 Core removal, test, 122 
 Corporation, applicant for bridge, 120 
 Cost of 
 
 Bridge, least, 124 
 Coffer-dam, 61, 76, 77 
 Concrete, 117 
 Dredgers, 103 
 Dredging, 103, 148 
 Driving piles, 48 
 Formula for, spans, 124 
 bridge, 124 
 piers, 125 
 
 Hoist-engines, 44, 45 
 Piers, 125 
 Pumps, 93, 148 
 Removing pier, 74 
 Spans, 124 
 
 Crevices in rock, see Rock 
 Cribs, 26, 33, in 
 Crib anchor, 33, 134, 135 
 Crib coffer-dam : see Coffer-dam 
 Current, strength of, 120 
 Cutting edges, So, 122, 147 
 Cutting shoe, 122 
 
 Cutwaters, 10, 18, 26, 66, 129, 130, 131 
 Cylinder 
 
 Bracing for, 83, 84 
 Calking for, 82 
 Guide for, 81 
 Pier, 33, 80, 82, 83, 87 
 Piles for, 83 
 Thickness of, 82, 83, 84 
 Damaged 
 
 Coffer-dam, 24, 32, 35, 60, 66, 76 
 Piles, 10 
 
 Danube river. 9, 40 
 Decking for coffer-dam, 134 
 Defects in 
 
 Cement, 114, 136 
 Piles, 10 
 Stone, 137 
 
 Deposit in coffer-dam, 134 
 Depositing concrete under water, see Con- 
 crete 
 
 Derricks, 102, 117 
 Derrick, see Pile-driver 
 Design of piers, see Piers 
 Direct connected pump, 97 
 
154 
 
 INDEX. 
 
 Disposal of excavation, 26, 60, 71 
 Diver employed, 31, 36, 76, 87 
 Docks, Victoria, B. C., 77 
 Dowels for stone, 137 
 Drawings to show 
 
 Bridge location, 120 
 
 Bridge plan, 120 
 Dredger 
 
 Capacity of, 101, 102, 103, 135, 148 
 
 Clam-shell, 102 
 
 Claw, 72, So, 102 
 
 Cost of, 103, 148 
 
 Derrick for, 102 
 
 Dipper, 103 
 
 Edward's Cataract pump, 101 
 
 Elevator type, 102 
 
 Engine for, 78, 148 
 
 Furnished, 134 
 
 Grapple, 102 
 
 Lancaster, 102 
 
 Osgood, 103 
 
 Pump, 78, 99, 101, 148 
 
 Sand-digger, 102 
 
 Scraper, 13 
 
 Seagoing, 101 
 
 Spoon, 13 
 Dredging, 10, 15, 80 
 
 Amount necessary, 16 
 
 Cost of, 102, 103, 105 
 
 Pumps for, 78, 99, 101, 148 
 
 Rock, 72 
 
 Soft bottom, 106 
 
 Wells for, 80 
 Drift in sand, 18 
 
 Drift bolts, 33, 36 38, 39, 57, 60, 71 
 Drilling, test, see Boring 
 Driver, see Pile-driver 
 Durability of piles, 40, 72 
 Earth bank coffer-dam, see Coffer-dam 
 Economic 
 
 Bridge cost, 124, 125 
 
 Coffer-dam construction, 26 
 
 Pier spacing. 120, 124, 125 
 Eddies, 129, 130, 131 
 Efficiency of pumps, 96, 148, 149 
 Ejector for priming, 101, 148 
 Electricity 
 
 Blasting by. 73 
 
 Hoisting by, 98, 117 
 
 Pumping by, 97 
 Engine, see Hoist 
 Erection, steel coffer-dam, 147 
 Estimates, 139, 146 
 European pier design, 127 
 Examination for bridge site, 120 
 Excavation (see Dredging) 7, 10, 60, 
 61 
 
 Classification, 135, 145 
 
 Disposal of, 26, 60, 71, 135 
 
 Measurement, 139 
 
 Rock, 72, 86, 145 
 
 Scraper for, 13 
 
 Spoon for, 14 
 
 Experiments 
 
 Piers, form of, 129, 130, 131 
 
 Puddle, 12 
 
 Timber, wet, 33 
 Exterior puddle, see Puddle 
 Facing for concrete, 72, in, 114, 143 
 Failure of 
 
 Coffer-dam, see Coffer-dam 
 
 Contractor to prosecute work, 139 
 
 Puddle, 28 
 Filling, see Puddle 
 Floating coffer-dam, 74 
 Footing course, 4, 117, 127 
 Form of 
 
 Foundation, 5, 124 
 
 Piers, 129, 130, 131 
 
 Sheet piles, 50, 51, 52, 53 
 Forms for concrete, in, 113, 115, 141, 142, 
 
 144 
 Formula for 
 
 Cost of hoists, 45 
 
 Cylinder thickness, 84 
 
 Economic span, 124 
 
 Pile loads, 49 
 
 Sheet pile thickness, 54, 56 
 
 Struts, 56 
 
 Fort Monroe, Va., 64 
 Forth Bridge piers, 86 
 Foundations 
 
 Ancient, I, 3. 4, 5, 40 
 
 Care, increased, I 
 
 Changes in, 136 
 
 Character of, 106, 117, 124, 146 
 
 Coffer-dam, origin, 3, 5 
 
 Concrete, see Concrete 
 
 Crib, early type, 5 
 
 Difficult, very, 120, 124 
 
 Doubt of obtaining, 125, 146 
 
 Encaissement, 3 
 
 Footing course, 4, 117, 127 
 
 Form of, 5, 124, 146 
 
 Grillage, 20, 24, 60, 67, 71, 72, 106 
 
 Open caissons, 3, 4, 13 
 
 Origin, sub-aqueous, 3 
 
 Piles and concrete, 3, 106, no 
 
 Piles, bearing, 106, 146 
 
 Piles under cylinders, 83 
 
 Pneumatic caisson, 5 
 
 Risk of, 125 
 
 Rock bottom, see Bottom 
 
 Roman, I 
 
 Steel shells, 33, 80, 82, 83, 87 
 
 Sub aqueous, 3, 77 
 
 Tropical, i 
 
 Frame for coffer-dam see Coffer-dam 
 Freshet, damage by, 66, 76 
 Friction lever, 44 
 Frost on mortar, 136 
 Gate valve for priming, 101 
 Girders, circular, 89, 147 
 Government 
 
 Approval, 120 
 
 Requirements, 120 
 
INDEX. 
 
 155 
 
 Grades, 135 
 
 Gravel bed, see Bottom 
 
 Gravel in puddle, 12, 15,26, 76, see Puddle 
 
 Grease for leaks, 30, 36 
 
 Grillage (see Foundation) 
 
 Removal, 74 
 Guide 
 
 Cylinder pier, 81 
 Piles, 7, 49, 57, 71 
 
 Pile-driver, 43 
 
 Pipe for drilling, 121 
 Guide for piles, 43, 57 
 Gunny sacks, 26, 28, 33. 36, 64, 76 
 Half-tide coffer-dam, 89 
 Hammer, see Pile-driver 
 Hand- 
 Derrick, 40, 41, 43 
 
 Pump, 93 
 
 Harlem ship-canal bridge, 36 
 Hoist engine for 
 
 Derrick, 117, 149, 150 
 
 Pile-driver, 44, 45, 68, 78, 149, 150 
 
 Scraper, 13 
 Hoist- 
 Cost of, 44, 45 
 
 Electric, 98, 117 
 
 Weight of, 149, 150 
 Huron river, Mich., 59 
 Hutcheson bridge, 6 
 Ice protection, 9, 10, 26, 129, 130, 131 
 Illinois & Miss, canal, 113 
 Illinois river, 62 
 Inspection, 139 
 Iron coffer-dam, 83, 86 
 Iron sheet piles, 91 
 Jet for pile-driver, 70 
 Kanavvah river, W. Va., 14, 117 
 Kankakee river, 62 
 Karun river, Persia, I 
 Key piles, 57 
 Knives for drill-rope, 121 
 Laitance of cement, 109 
 Lansdell siphon, 93 
 Largest 
 
 Arch, 3 
 
 Coffer-dam, 8 
 Layers of concrete, 109, 113, 138, 143, 144, 
 
 145 
 Laying concrete, rules for, 113, 138, 143 
 
 M5 
 Leaks cured by 
 
 Asphalt, 65 ' 
 
 Boxing in, 32, 39, 60 
 
 Calking joints, 20, 36 
 
 Candle wicking, 20, 39 
 
 Cane-stalks crushed, 28 
 
 Canvas funnel, 32 
 
 Clay cylinders, 29 
 
 Clay dams, 89 
 
 Concrete in sacks, 66 
 
 Exterior puddle, 28, 78 
 
 Gravel and clay, 26 
 
 Grease, 30, 36 
 
 Leaks cured by Continued. 
 
 Grouting, 89 
 
 Hot asphalt, 65 
 
 Manure, 28, 32 
 
 Packing puddle, 12, 28, 77 
 
 Puddle, exterior, 28, 78 
 
 Puddling rock seams, 25 
 
 Repuddling, 28 
 
 Round braces, 30, 38 
 
 Sacks, 26, 36, 66, 76 
 
 Sheet piles, 12, 28 
 
 Stiff grease, 30, 36 
 
 Stock ramming, 12, 28, 77 
 
 Straw and gravel, 20, 28 
 
 Tarpaulin, 30, 32, 33, 35, 36, 65 
 
 Washers on rods, 30 
 
 Water-head, 32, 39 
 Ledges, see Rock 
 Length, economic span, 124, 125 
 Leveling course concrete, 107, 117 
 Lift of pumps, 96, 100, 148, 149 
 Little Bras d'Or river, Canada, 82 
 Location of 
 
 Bridge, 120 
 
 Coffer-dam, 86, 87 
 
 Piers, 120 
 
 Pumps, 100 
 
 Manure for leaks, 28, 32 
 Map of bridge location, 120 
 Maslin pump, 96 
 Masonry 
 
 Ashlar, 136 
 
 Footing courses, 74, 117 
 
 Laying, 137 
 
 Marking stones, 74 
 
 Measurement, 139 
 
 Removing, 73, 74 
 
 Rubble, 86, 90 
 
 Specifications for, 136, 137, 138 
 Mass, sewerage system, 60, 61 
 Mattresses, 4 
 Maul for driving pipe, 122 
 Maul as pile-driver, 40 
 Measurement of work, 139 
 Melan Arch, Topeka, 78 
 Metal coffer-dam, 35, 83, 86, 147 
 Missouri river, 127 
 Mississippi river, 20, 32, 67 
 Monolithic concrete, 72, in, 112, 113, 143 
 Morison's pier design, 125 
 Mortar, cement, 136, 143. 145 
 Movable coffer-dam, see Coffer-dam 
 Mud, see Bottom 
 
 Nasmyth hammer, 14, 45, 46, 47 48, 49 
 Natural cement, in, 136, 143, 145 
 Navigable rivers, see River 
 Navigation, needs of, 120 
 
 Interference with, 135 
 New York State canals, 45, 50 
 Nippers, pile-driver, 43 
 Obstruction 
 
 To boring. 121 
 
 By piers, 125 
 
1 5 6 
 
 INDEX. 
 
 Ohio river, 15, 133 
 
 Oil paper for concreting, 142 
 
 Origin of 
 
 Coffer-dam, 3, 5 
 
 Foundations, 3 
 Packing puddle, 12, 28, 77 
 Painting, 65, 147 
 Parnitz river, Germany, 72 
 Payment, manner of, 134 
 Pierce boring auger, 121 
 Piers 
 
 Architectural design, 125, 127, 131 
 
 Batter of, 125 
 
 Bracing for cylinders, 83 
 
 Concrete, 72, in, 143, 144 
 
 Coping for, 125, 127, 129 
 
 Cost of, for economy, 125 
 
 Cylinder, 33, 80, 82, 83 
 
 Design of, 125. 127, 129, 130, 131 
 
 Economic spacing, 120 
 
 European design, 127 
 
 Experiments en form, 129. 130, 131 
 
 Filling of concrete, So, 82, 143 
 
 Forth bridge, 86 
 
 Hutcheson 6 
 
 Location of, 120, 125 
 
 Morison's design, 125 
 
 Obstruction of, 125, 129, 130, 131 
 
 Pivot, 82 
 
 Relation to spans, i, 124 
 
 Removal, 72, 74 
 
 Starlings of, 125, 129, 130, 131 
 
 Thickness of tubular, 84 
 
 Tubular steel, 33, 80, 82, 83 
 Pile-driver 
 
 Ancient, 5. 40, 41 
 
 Beetle for, 40' 
 
 Bull-wheel for, 41 
 
 Clamps, 43 
 
 Cost of outfit, 43, 44 
 
 Cram-Nasmyth, 49 
 
 Derrick, 41/42, 43. 45 
 
 Engine, 44, 45, 78, 149. 150 
 
 Friction lever, 44 
 
 Guides, 43 
 
 Hammer, 41, 43, 44, 68. 77, 78 
 
 Hand derrick, 40, 41, 43 
 
 Hoist engine for, 44, 45, 68, 78, 149, 150 
 
 Horse-power, 41, 43 
 
 Lidgerwood, 43 
 
 Maul, 40 
 
 Nasmyth, 14, 45, 46, 47, 48, 49 
 
 Nippers, 43 
 
 Rock drill used, 14 
 
 Scow for, 43, 44, 45 
 
 Sheet pile, 14, 41 
 
 Sledge, 40 
 
 Tongs, 43 
 
 Warrington-Nasmyth, 46, 47 
 
 Water jet, 70 
 
 Windlass, 40 
 Piles- 
 Ancient use, 3, 4, 5, 40 
 
 Piles Continued. 
 
 Bearing, 106, 146 
 
 Bearing power, 49, 146 
 
 Blasting out, 73 
 
 Cost driving, 48 
 
 Clamps, 43 
 
 Damaged, 10 
 
 Durability of, 40, 72 
 
 Guide 7, 57, 49, 71 
 
 Guiding, 43 
 
 Key, 57 
 
 Payment for, 139, 146 
 
 Pointing, see Pointing 
 
 Protection, 134 
 
 Pulling, 50, 73 
 
 Pulling lever, 50 
 
 Pulling scow, 50 
 
 Rings for, 70 
 
 Sawing off, 50, 83, 146 
 
 Sheet piles, ancient, 4 
 See sheet piles 
 
 Shoes, 50, 53 
 
 Specifications for, 135, 141, 146 
 
 Splitting of, 43 
 
 Temporary, 135 
 
 Under cylinders, 83 
 Pivot pier 
 
 Cylinders for, 82 
 
 Coffer-dam for, 20, 36, 38, 39, 147 
 Pointing piles, 24, 50, 51, 53, 57, 60 
 Pointing with mortar, 136 
 Porous bottom, 16, 28, 141 
 Portland cement, 72, 113, 115, 116, 142 
 Potomac river, 63 
 Primers for pumps, 100, 101, 148 
 Pressure of 
 
 Puddle, 54 
 
 Water, see Water 
 Proportions for concrete, 67, 72, 107, no, 
 
 in, 116, 138, 143, 145 
 Protection of 
 
 Bank, 4 
 
 Coffer dam, 26, 33, 134 
 
 From ice, see Ice 
 Puddle- 
 Blue clay, 72 
 
 Chamber, 7, 10, 33, 36, 38, 56,66, 72, 74,77 
 
 Clay, 7, 17, 26, 33, 66, 88 
 
 Clay and gravel, 12, 15, 26, 76, 134 
 
 Concrete. 39, 78, 87 
 
 Experiments, 12 
 
 Exterior, 17, 20, 25, 26, 28. 33, 63, 66, 71, 
 76, 77 
 
 Failure of, 28 
 
 Pressure of, 54 
 
 Sacked, 26, 28, 33, 64 
 Pulling piles, 50, 73 
 Pulling test tubing, 124 
 Pulsometer, 30^ 32, 90, 94, 95 
 Pumping, 15, 17, 18, 25, 30, 32, 39, 61, 63, 
 64, 66, 72, 76, 89 
 
 Amount of, 92 
 
 Electricity for, 97 
 
INDEX. 
 
 157 
 
 Pumps 
 
 Ancient, 92, 93 
 
 Bascule, 92 
 
 Box, 93 
 
 Bucket- wheel, 92 
 
 Capacity, 77, 7, 93, 94, 99, 101, 135, 148 
 
 Centrifugal, 15, 17, 18, 30, 39, 61, 63, 66, 
 77, 78, 90, 96, 97, 98, 99, 100, 148, 149 
 
 Chapelet, 92, 93 
 
 Chattanooga plant, 99 
 
 Cost of, 93, 148 
 
 Direct connected, 97 
 
 Double suction, 100 
 
 Dredging, 78, 99, 101, 148 
 
 Edward's cataract, 101 
 
 Efficiency of, 96 
 
 Ejector for priming, 101, 148 
 
 Electric, 97 
 
 Forth bridge, 99 
 
 Furnished, 134 
 
 Gate valve primer. 101 
 
 German high test, 97 
 
 Hand, 93 
 
 Heald & Sisco, 97, 148 
 
 Lift of, 96, 100, 148 
 
 Location, best, 100 
 
 Maslin, 96 
 
 Piston of dredging. 101 
 
 Primers, 100, 148 
 
 Pulsometer, 30, 32, 90, 94, 95 
 
 Reciprocating, 96 
 
 Sampling, 121, 122 
 
 Siphon, 93 
 
 Speed for, 149 
 
 Strainers for, 98 
 
 Suction details, 98 
 
 Suction pipe, 98, 100, 148 
 
 Sump or well for, 60, 99 
 
 Tests of, 96, 97 
 
 Weight of, 148 
 
 Wooden, 93 
 Quality of 
 
 Cement, 114, 136, 142, 145 
 
 Timber, 138, 139, 146 
 Quicksand, 67, 135 
 Rammer for puddle, 28, 77 
 Red river, U. S., in 
 Rejection of material, 137, 139 
 Removal of 
 
 Coffer-dam, 20, 33, 74, 134, 147 
 
 Grillage, 74 
 
 Piers, 72, 74 
 
 Piles, 50, 73 
 
 Test core, 122 
 Republican river, Kan., 20 
 Requirements, War Dep't, 120 
 Rhine river, 5 
 Rings for piles, 70 
 Rip-rap, 26, 72, 83 
 Rivers, navigable, 120 
 River 
 
 Aa, Russia, 83 
 
 Arkansas, 20, 70 
 
 River Continued. 
 
 Bear, Can., 83 
 
 Charles, Boston, 63, ITO 
 
 Clyde, Scotland, 6 
 
 Coosa, Ala., 74, no, 117 
 
 Danube, 9, 40 
 
 Huron, Mich., 59 
 
 Illinois, 62 
 
 Kanawah, W. Va., 14, 117 
 
 Kankakee, 111., 62 
 
 Karun, Persia, i 
 
 Little Bras d'Or, 82 
 
 Missouri, 127 
 
 Mississippi, 20, 32, 67 
 
 Ohio, 15 
 
 Parnitz, Germany, 72 
 
 Potomac, 63 
 
 Red, in 
 
 Republican, Kan., 20 
 
 Rhine, 5 
 
 Sault Ste. Marie, 28 
 
 Schuylkill, Pa., 74 
 
 Scioto, Ohio, 13 
 
 Soane, France, 109 
 
 St. Lawrence, 18 
 
 Tennessee, 66 
 
 Thames, 4, 77 
 
 Western, U. S., 17, 18, 20 
 Riveting 
 
 Boiler, 80, 82, 147 
 
 Water-tight, 80, 82, 147 
 Roads, construction, 3 
 Robinson, coffer-dam, 24 
 Rock- 
 Bottom, see Bottom 
 
 Crevices, 25, 28, 39, 66, 89, 107 
 
 Joint with sheet piles, 72 
 
 Ledges, 86 
 
 Stepping of, 86, 107 
 Rock-drill pile-driver, 14 
 Rod bracing, 30, 38, 67, 134 
 Roman foundations, I 
 Rubble masonry, 86, 90 
 
 Rules laying concrete, 113, 138, 143, 144, 145 
 Sacked puddle, see Puddle 
 Sacks used, 26, 28, 33, 36, 64, 66, 76 
 Samples of borings, 121, 122 
 Sampling pumps, 121, 122 
 Sand (see Bottom) 
 
 For concrete, in, 115, 136, 143, 145 
 
 Digger, 102 
 
 Drift in, 18 
 
 Pump, 121, 122 
 
 Shells in, 77 
 
 Sault Ste. Marie river, 28 
 Sawing off piles, 50, 83 
 Schuylkill river, 74 
 Scioto river, Ohio, 13 
 Scow, pile pulling, 50 
 Scow, see Pile-driver 
 Scraper, 13 
 
 Sec'y of War, approval, 120 
 Setting time, concrete, no, 114, 143,144, 145 
 
158 
 
 INDEX. 
 
 Sewer coffer-dam, 60, 61 
 
 Shale, 60 
 
 Sheet pile coffer-dam, see Coffer-dam 
 
 Sheet piles 
 
 Calculations, 54, 56 
 
 Clamps for, 57 
 
 Close, 135 
 
 Compound, 52, 53, 61, 66 
 
 Driver for, 14, 41 
 
 Early use, 4, 6, 7 
 
 Forms of, 50, 51 
 
 Guides, 57 
 
 Leak remedy, 12, 28 
 
 Metal, 91 
 
 Old, 72 
 
 Plank, 35, 50, 59, 60, 66, 67, 77, 134 
 
 Pointing, 24, 50, 51, 57, 60 
 
 Rock joint with, 72 
 
 Shoes for, 50, 51, 52 
 
 Slanting, 60, 61 
 
 Square, 8, 10, 24, 51, 60, 77 
 
 Thickness, 53, 54, 56 
 
 Tongue and groove, 20, 24, 51, 60, 71, 
 76, 77, 78 
 
 V shape, 20, 51 
 
 Wakefield, 14, 20, 53, 61, 62, 63, 64, 141 
 Shells in bottom, 77 
 Shocks of waves, 83, 89 
 Shoe for 
 
 Piles, 50, 53 
 
 Pipe, 122 
 
 Sheet piles, 50, 51, 52 
 Shoring, see Bracing 
 Silt bottom, 33 
 Sinking coffer-dam, 20, 76 
 Siphon, 93 
 Site of bridge, 120 
 Site, examination of, 120, 124 
 Slanting piles, 60, 61 
 Sledge for pile-driver, 40 
 Sluice, 7, 87 
 
 Soane river. France, 109 
 Soapstone bottom, 20 
 Sounding rod, 86 
 Soundings, 86, 120, 121 
 Spans 
 
 Cableway, 117, 118 
 
 Economic formula, 125 
 
 Economic length, 124, 125 
 
 Length of, 124 
 
 Relation to piers, I, 124 
 Spacing of piers, 120, 124, 125 
 Spears for drill rope, 121 
 Specification for 
 
 Coffer-dam, see Coffer-dam 
 
 Cement, see Cement 
 
 Foundation, 141, 146 
 
 Masonry, 136, 137, 138 
 
 Piles. 135, 141 146 
 
 Steel coffer-dam, 147 
 
 Timber, 138, 139, 146 
 Speed for pumps, 149 
 Splicing coffer-dams, 67, 147 
 
 Springs in bottom, 32 
 
 Spuds, 75 
 
 Staging to locate pier, 86 
 
 Starlings, 10, 18, 26, 66, 125, 129, 130, 131 
 
 Steel coffer-dam, 83, 86, 147 
 
 Steel shells, So, 82. 83 
 
 St. Lawrence river, 18 
 
 Stock rammer, 12, 28, 77 
 
 Stone 
 
 Concretes., in, 115, 143, 145 
 
 Defects in, 137 
 
 Dressing, 137 
 
 Protection, 83, 135 
 
 Quality of, 136 
 
 Rubble, 137 
 
 Samples, 137 
 
 Substitute for, So 
 Strainer for pump, 98 
 Struts, see Timber 
 Suction-pipe, 98, 148 
 Sump for pump 60, 99 
 Suspension bridge tower, 8 
 Swab, 121 
 
 Swift water, see Water 
 Tables of 
 
 Pumps, centrifugal, 148 
 
 Pumps, dredging, 148 
 
 Pump speed, 149 
 
 Hoisting engines, 149, 150 
 Tarpaulin used, 30, 32, 33, 35, 36, 65 
 Tennessee river, 66 
 Test borings, see Borings 
 Tests of 
 
 Cement, 115, 136, 142, 145 
 
 Pumps, 96, 97 
 Thames river, 4, 77 
 Thickness of 
 
 Cylinders, 84 
 
 Sheet piles, 53, 54, 56 
 Tide coffer-dam, 8, 53, 63, 86, 89 
 Tide, see Water 
 Timber 
 
 Casing, 5 
 
 Framing, 135 
 
 Piles, see Piles 
 see sheet piles 
 
 Price for, 139, 146 
 
 Scarcity of, 79 
 
 Specifications, 138, 139, 146 
 
 Struts, 7, 30, 33, 33, 39, 5^, 64 
 
 Water-soaked, 33 
 Tongs- 
 Pebble, 124 
 
 Pile-driver, 43 
 
 Tongue and groove, see Sheet piles 
 Tools furnished, 134 
 Topeka coffer dam, 78 
 Trezzo arch, i 
 Tripod for test boring, 121 
 Tube for 
 
 Concreting, 108, no 
 
 Drilling, 121 
 
 Pier, 33, 80, 82, 83, 87 
 
INDEX. 
 
 59 
 
 Van Duzen jet, 93 
 Velocity of water, 129, 130, 131 
 Victoria, B. C., docks, 77 
 Voids in masonry. 136 
 V shape pile joint, 20, 51 
 Wakefield sheet piles, see Sheet piles 
 Wales- 
 Calculation of, 56 
 
 Ordinary, 7, 35, 59, 134 
 War Dep't requirements, 120 
 Washers for leaks, 30 
 Water 
 
 For concrete, 113, 114, 143 
 
 Deep, 8, 10, 63 
 
 Eddies, 129, 130, 131 
 
 High, 118, 119, 120 
 
 Jet, 70 
 
 Low, 120 
 
 Pressure, 20, 25, 28, 32, 35, 54, 85, 
 
 Water Continued. 
 
 Shallow, i, 5, 13 
 
 Shock of waves, 83, 89 
 
 Soaked timber, 33 
 
 Swift, 10, 26, 32, 107 
 
 Tide, 8, 86 
 
 Velocity, 129, 130, 131 
 Water-tight compartments, 76 
 Water-tight riveting, So, 82, 147 
 Waterway, 120, 129 
 Weight of 
 
 Hoist engines, 149, 150 
 
 Pumps, 148 
 Well driller, 121 
 Well for pump, 60, 99 
 Wells in concrete, 114 
 Wellington pile formula, 49 
 Western, U. S., rivers, 17, 18, 20 
 Windlass pile-driver, 40 
 Wooden pump, 93 
 
Wakefield Triple=lap Sheet Piling, 
 
 This sheeting matches perfectly ; can be made as wanted 
 at the work, of any available sound lumber.; stands driving 
 without an equal, and stops water absolutely at such trifling 
 cost that it invariably proves satisfactory. 
 
 PATENTED. 
 
 Royalty charge, 25 cents per foot, of completed work ; 
 i.e. , a coffer-dam 25' X 50', sheeted on four sides, amounts to 
 150' @ 25c. $37.50. 
 
 USED BY ARMY ENGINEERS, RAILWAY ENGINEERS, 
 CITY ENGINEERS, CONTRACTORS, ETC, 
 
 WAKEFIELD SHEET=PILING CO., 770 The Rookery, Chicago, 111. 
 
 Heald & Sisco Centrifugal Pumps 
 
 COFFER-DAM WORK AND GENERAL CONTRACTING, 
 Our New Special Hydraulic Dredging and Sand Pump 
 
 embodies the latest improvements suggested by the experience of 
 contractors all over the country. We confidently recommend it, 
 therefore, as the best and most efficient pump manufactured. Some 
 of the new features are : an improved piston ; a disk on the suction 
 side, which can be easily removed to get at the inside without dis- 
 mantling the whole pump; a shaft-bearing in the pump-shell adjust- 
 able to take up wear. We also furnish, if desired, steel wearing 
 plates and cast-steel liners for the inside of the shell, which lengthen 
 the life of the pump considerably. Write for catalogue containing 
 full particulars, and ask for testimonials and prices. 
 
 MORRIS MACHINE WORKS, 
 
 New York Office, 39-41 Cortlandt St, BALDWiNSVILLE, 5^. Y. 
 
 Chicago Agents, HENIOH & HUBBELL, 61-69 Worth Jefferson St. 
 
ATLAS PORTLAND CEMENT 
 
 Standard American Brand. 
 
 Used by the Leading Engineers throughout the 
 United States* 
 
 SPECIALLY ADAPTED FOR 
 
 HEAVY MASONRY WORK 
 
 SZEZSTID 
 
 ATLAS CEMENT CO., 
 
 143 LIBERTY STREET, NEW YORK CITY. 
 
 LIDQERWOOD Hoisting Engines 
 
 are built to gauge on the Duplicate Part 
 System. Quick Delivery Assured. 
 
 STANDARD POR QUALITY AND DUTY. 
 
 FOR PILE DRIVING, 
 Dock and Bridge Building, 
 Contractors, and General Hoisting. 
 
 OVER 13,000 IN USE. 
 
 CABLEWAYS, 
 
 HOISTING AND CONVEYING DEVICES, STEAM AND ELECTRIC HOISTS, 
 for General Contract Work. 
 
 SDEHSTID iF-oie, X,^L.T:EST O-^T^ZLOGKCTIEJ. 
 
 LIDQERWOOD MFG. CO., 96 Liberty St., New York. 
 
SHORT-TITLE CATALOGUE 
 
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 1 1 1974 
 
 -., 
 
 MAR 8 T* X 9 
 
 LD 21-95m-7,'37