U(~ ra(. ^ f PARIS UNIVERSAL EXPOSITION, 1889. AND ARCHITECTURE, ltY WILLIAM WATSON, Ph. D., Fellow of the American Academy of Arts and Sciences; member of the Xalional Academy of Cherbourg, of the French Society of Civil Engineers, of the Prussian Society of Industrial Engineers, of the American Society of Civil Engineers, of the American Society of Mechanical Engineers; late 17. S. Commis- sioner to the Vienna Exposition; member of the Interna- tional Jury at the Paris Exposition of 1S7S, etc. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1892 . ERRATA. Page. Sect. Line. 547 36 for Fontaine put Fontaine’s. 551 23 for Nougier put Nouguier. 551 25 for Contemin put Contamin. 551 25 for Groclaude put Grosclaude. 555 4 21 for Boulonge put Boulogne. 555 5 9, 10 for with a border 0.010 meters th meter thick. 566 36 3 for Seine put same. 566 36 4 for brace put braces. 570 41 7 for apron put flooring. 571 5 for apron put flooring. 592 57 14 for by put from. 627 110 2 for that put this. 672 173 7 after tide put the gates are open and. 672 173 7 after vessels put of any length. 722 234 12 for adopted put followed. 741 14 for 165 put 151. 767 286 20 for allows put allow. 809 328 2 after of put the upright cut by. 846 8 for cars put ears. 883 412 2 for there put three. Plate IV. for Reynard put Reguard. UNIVERSAL EXPOSITION OF 1889 AT PARIS. ILLUSTEATIONS IN THE REPORT ON CIVIL ENGINEERING, PUBLIC WORKS, AND ARCHITECTURE. Plate I. View of the hydraulic canal lift at Les Fontinettes 552 Plate II. View of the trough basin at Les Fontinettes 554 Plate III. Pumping machinery at Les Fontinettes 558 Plate IV. Model of Poses dam ; by Regnard Brothers, Paris 592 Plate V. Construction of the quays at Calais ; process of sinking the piles by means of water jets 674 Plate VI. Construction of the outer harbor quays at Calais ; process of sinking the foundation curbs by means of water jets. 678 Plate VII. Port of Havre; lock gates of the Bellot basin 696 Plate VIII. Framework of the iron dock sheds at Havre 700 Plate IX. The lower portion of the arch of the Garabit viaduct 762 Plate X. Garabit viaduct during the process of erection 766 Plate XI. Iron framework of a Paris store (the Magazin duPrintemps) 804 Plate XII. The Eiffel Tower; iron caissons, used with compressed air in building the foundation of a pier 812 Plate XIII. The Eiffel Tower; view 1 of a pier with its inclosing walls. . 814 Plate XIV. The Eiffel Tower; new scaffolding, 45 meters high, for unit- ing the isolated piers 818 Plate XV. The Eiffel Tower; details of the ironwork of the structure. 820 Plate XVI. The Eiffel Tower; the erecting crane used above the second story 824 Plate XVII. The first story of the Eiffel Tower 826 Plate XVIII. Complete view of the Eiffel Tower 830 Plate XIX. View of Machinery Hall, showing the end truss girder and the gables 856 Plato XX. Interior view of Machinery Hall 856 Plates XXI and XXII. Two groups of figures supporting the lintel of Ma- chinery Hall; one by M. Barrias, representing electricity; the other by M. Chapu, personifying steam 862 Hydraulic canal lift at Les Fontinettes. Figure 1. Plan of the hydraulic lift at Les Fontinettes 553 Figure 2. Longitudinal section along the axis of the trough 554 Figure 3. Cross section through the transverse axis of the lift 556 Movable dam at Suresnes on the Seine. Figure 4. Map and general plan of the dam 565 ILLUSTRATIONS. XIII Civil Engineering, Public Works, and Architecture— C ontinued. p aKe . Figures 5-7. Movable frame of the Navigable Pass; elevation and sections 567 Figure 8. Movable frame, with its panels 568 The Marly dam on the Seine. Figure 9. Fixed frame used in the Marly dam 571 Figure 10. Method of anchoring the frame 571 New river lock at Bougival. Figure 11. Map showing the situation of the lock 573 Figure 12. Machinery house and accumulator; longitudinal section 575 Figure 13. Machinery house and accumulator; horizontal section 576 Figure 14. Machinery house ; transverse section 577 Apparatus for operating the lock sluices by hydraulic power alone. Figures 15 and 16. Vertical section and elevation 578 Figure 17-18. Plan and section of the sluices 579 Combined apparatus for operating the lock sluices either by hand or by hydraulic poiver. Figures 19-23. Elevation, plan and sections 580 Figures 24 and 25. Valve chest; vertical sections 581 Hydraulic apparatus for opening and closing the lock gates. Figures 26 and 27. Longitudinal section and plan 582 Figures 28 and 29. Sections 583 Hydraulic capstan. Figures 30 and 81. Sections 585 Figure 32. Plan (cover removed) 586 Figures 33 and 34. Elevation and sections 587 Movable dam at Poses on the Seine. The uprights and curtains. Figure 35. Longitudinal section in front of the uprights 589 Figure 36. Transverse section 590 Figures 37 and 38. Hoisting windlass 590 Figure 39. Section of the chain stop 590 Figures 40 and 41. Details of the curtain hinges and shoe 591 Figure 42. Transverse section 593 Figures 43 and 44. Sections of members 593 Figure 45. Plan and horizontal section of the bridge at different heights. 594 Figures 46 and 47. Sections of members 594 Figure 48. Upstream elevation of the intermediate girder 595 Figure 49. Map showing position of the new movable dam at Poses 597 Figure 50. Elevation and section of the abutment on the left bank, with the anchorage for the foundations 598 Figure 51. View of the dam from below 599 Figure 52. View of the dam from above; raising a frame 601 Figure 53. View from below; rolling a curtain 601 Figures 54 and 55. Mode of suspending the frames (Port-Mort Dam) .... 602 Movable dam at Villez. Figure 56. General view of the dam 607 Figure 57. Lowering the frames at Villez Dam 608 Figures 58 and 59. Windlass for hoisting and lowering the curtains, and the mode of unshipping and transporting them .... 609 Movable fish way at Port-Mort. Figure 60. View of the fish way 611 XIV ILLUSTRATIONS. Civil Engineering, Public Works, and Architecture — C ontinued. Torcy-Neuf reservoir for the Central Canal. Page. Figure 61. Map of the reservoir 613 Figure 62. Cross section of the dike, the water tower and the culvert. . 615 Figures 63-65. Section, elevation, and details of the sluice 617 Figures 66-69. Elevation and vertical and horizontal sections of the guard gate, with details 618 New high lift locks on the Central Canal. Figures 70-74. Sections of a high-lift lock 620 Figures 75 and 76. Half cross sections through the axes of the sluice pits. 621 Figure 77. Fontaine’s cylindrical sluice ... 622 Figures 78 and 79. Elevation and section of the lowei gates of the lock. . 623 Cable towage for boats on canals and rivers. Figure 80. Details of the pulley and the rope connections 626 Figures 81 and 82. Elevation and plan of a double pulley for a concave angle 628 Figure 83. Single pulley for concave angles 629 Figures 84 and 85. Hooking-on and casting-off grip 629 Figure 86. The grip, with the tow rope 630 Towage by a submerged chain and a fireless engine. Figures 87 and 88. Plan and sections of the chain towboats 633 System for supplying the canal from the Marne to the Rhine. Figure 89. Vertical section through the pumping station at Pierre-la Treiche 636 Figure 90. Plan of the same 637 Oscillating bridge over the Dames Canal lock. Figure 91. Diagram showing the action of the bridge 638 Balanced gates on the Rhone and Cette Canal. Figure 92. Segmental balance gate at Croisee-du-Lez 640 Braye-en-Laonnois Tunnel. Figure 93. Geological section 643 Figure 94. Sections showing details of the construction of the tunnel... 644 Figures 95 and 96. Sections of the air lock 645 Figure 97. The method adopted for ventilating the tunnel 647 Embankment ivorks for the improvement of the tidal Seine. Figure 98. Map of the tidal Seine 650 Figures 99-101. Schemes A, B, and B 2 , for training the river through its tidal estuary 661 Figure 102. Scheme C 662 Figures 103 and 104. Schemes D and D bis 663 Figure 105. Scheme E 664 Figure 106. Scheme E bis ... 665 Figure 107. Scheme F 666 Calais Harbor works. Figure 108. Plan of Calais Harbor 671 Figure 109. Cross sections of the dike and quays 675 ILLUSTRATIONS. XV Civil Engineering, Public Works, and Architecture— Continued. p aKe . Figure 110. Cross section on a larger scale of the Northeast quay 070 Figures 111-113. Section and plans of a curb 078 Figure 114. Arrangements of water jets for lowering a curb 078 Figure 115. Section of a finished curb 079 Figure 110. Method of cementing two consecutive blocks together 079 Figure 117. Profile of the eastern quay wall of the eastern dock 083 New outer harbor at Boulogne. Figure 118. Map of the port of Boulogne 688 Figure 119. General view of the new deep-water harbor 690 Figure 120. Cross section of the parallel dike b 691 Port of Havre — Bellot lock and trail wave-breaker. Figure 121. Transverse section of the Bellot lock 694 Figures 122 and 123. Elevation and plan of the revolving bridge over the lock 695 Figures 124 and 125. Elevation and section of a leaf of the lock gates . . . 096 Figure 126. Lifting press and wedge of the revolving bridge 698 Figure 127. Apparatus for operating the lock gates ; elevation and plan of a leaf 698 Figure 128. Complete plan of the lock gates with the operating appara- tus 699 Figure 129. Iron wave-breaker 701 Canal from Havre to Tancarville. Figures 130-133. Elevation, half plan, and sections of the Tancarville lock gates 703 Slipway at Rouen for the repair of ships. Figure 134. General plan of the slipway 705 Figure 135. Cross section 706 Figure 136. Hauling machinery ... 706 Figure 137. Method of attaching the compensating cable to the cradle.. 707 Figure 138. Details of the shores 708 Port of Honfleur. Figure 139. Plan of the port of Honfleur and the sluicing basin 709 Figures 140 and 141. Apparatus for closing the sluicing lock at Honfleur. 710 Figure 142. The feeding-weir gates of the sluicing basin 713 Figure 143. Siphonage between the basins; sections of the siphons 716 Traversing bridge at St. Malo St. Servan. Figure 144. Section of the bridge, and details 718 Figure 145. Diagram of the operation of the recuperator 719 Figure 146. Vertical section and plan of the recuperator 719 Figure 147. Horizontal section of the recuperator press 720 Hydraulic works and pneumatic foundations at Genoa. Figure 148. Transverse section of the movable caissons used for drilling the rock for the purpose of submarine blasting 727 Figure 149. Transverse section of the movable caissons used in laying the masonry under water 727 Figure 150. Elevation and longitudinal section of the same 728 XVI ILLUSTRATIONS. Civil Engineering, Public Works, and Architecture — Continued. page. Figures 151-156. Details of the excavation lock 729 Figure 157. Great floating caisson used in laying the flooring of Basin No. 2; transvei'se section 730 Figures 158 and 159. Positions of the caissons, with and without ballast. 732 Figures 160 and 161. Caissons at work 732 Figure 162. Method of laying the flooring of a basin 734 Figure 163. Quay walls in arcades, Quai des Graces; longitudinal section . 734 Figure 164. Details of the iron centers 735 Port of Rochelle — Foundations of jetties at La Pallice. Figure 165. Plan of the outer harbor of La Pallice 736 Figure 166. Caisson raised from the block 737 Figures 167 and 168. Caisson resting on jacks 739 Figure 169. Method of closing the space between the blocks 742 Figures 170-172. Sections showing the w r alls under the panels and the method of holding the panels 743 The new steel bridge at Rouen. Figures 173 and 174. Elevation and plan 746 Figure 175. Upstream elevation of Pier No. 2 747 Suspension bridge at Tonnay-Charente. Figure 176. General view of the bridge 749 Figures 177 and 178. Method of attaching the cable and suspension rods. 750 Figure 179. M. Anodin’s alternately twisted cable 751 The lifting bridge at La Villette, Paris. Figure 180. Elevation 752 Figure 181. Transverse section 753 Figure 182. System of guiding the bridge 754 Figure 183. Details of a press and the superstructure 754 Figure 184. Three-way cock 755 The Garabit viaduct. Figure 185. General view of the Garabit viaduct 757 Figure 186. Elevation of the central portion, and sections of the members. 760 Figures 187 and 188. Wind bracing 760 Figure 189. Elevations of pier, and cross sections of members 762 Figure 190. Erection of the iron arch; beginning of the process of erec- tion 764 Figure 191. Appearance in an advanced stage of erection 765 Gour-JSoir viaduct. Figure 192. General view of the structure 768 Viaduct over the river Tardes. Figures 193 and 194. Elevation and plan of the viaduct 770 Consolidation of the side slopes of the railway cutting at La Plante. Figure 195. View of the slopes after the completion of the work 772 Tunnel through Cabres Pass. Figure 196. Half sections of the tunnel 774 Figure 197. Center used in the construction •» 774 ILLUSTRATIONS. XVII Civil Engineering, Public Works, and Architecture— C ontinued. Cubzac Bridge over the Dordogne. Paere. Figure 198. Partial elevation of the Cubzac Bridge and viaduct 776 Figure 199. Elevation of a pier of the viaduct of approach (left bank) . . . 777 Figure 200. Elevation of an abutment 777 Figure 201. Elevation of an iron pier 778 Construction of the Custelet, the Laveur, and the Antoinette Bridges. Figure 202. Elevation of the Castelet Bridge 782 Figure 203. View of the Antoinette Bridge and section of the viaduct . . . 783 Figure 204. Elevation of the Laveur Bridge 783 Figure 205. Center of Castelet Bridge ; elevation of a truss 785 Figure 206. Antoinette Bridge ; elevation of a truss 786 Figure 207. Center of the Laveur Bridge 787 Figures 208 and 209. Supports for the rings 788 The Ceret Bridge. Figure 210. Elevation, half plan, and half horizontal section 791 The crossing of the Garonne at Marmande. Figure 211. Plan of the submersible plain of the Garonne near Marmande. 792 Figure 212. Longitudinal section of the roadway across the plain 793 Figures 213-219. Masonry caissons used in building the foundations of the viaducts 795 Bridge over the Gave D'Oloron and the Gravona Bridge. Figure 220. View of the bridge over the Gave D'Oloron 797 Figure 221. View of the Gravona Bridge (railroad from Ajaccio to Cortej 799 Specimens of iron construction in Paris. Figure 222. Pneumatic apparatus used for the foundations of the Mag- azin du Printemps 802 Figures 223-225. Transverse sections of the pillars 804 The Eiffel Tower. Figure 226. Diagram of the resistance of the simple lattice 807 Figure 227. Diagram of the stability of the Eiffel Tower when exposed to the pressure of the wind ; two cases 807 Figure 228. General plan of the foundations 810 Figure 229. Longitudinal section of the Champs de Mars at piers 1 and 2. 811 Figure 230. Longitudinal and transverse sections of the iron caisson 811 Figure 231. View and section of a caisson showing the underground work and the shafts for the men and the materials 812 Figure 232. Plan and section of pier No. 1 814 Figure 233. Anchorage of the foundations 815 Figure 234. Erection of the tower; appearance in August, 1887 816 Figure 235. The erecting cranes used in the construction of the first and second stories 819 Figure 236. View of the first story 820 Figure 237. Details of the hydraulic jack 821 Figure 238. Operation of lifting one standard of the tower by an hydraulic jack 822 Figure 239. Arrangement of the crane for constructing the tower above the second story 823 Figure 240. Campanile of the tower 825 Figures 241 and 242. Verification of the verticality of the tower 828 H. Ex. 410 — VOL III II XVIII ILLUSTRATIONS. Civil Engineering, Public Works, and Architecture— C ontinued. The Machinery Hall. Page. Figure 243. General plan of the foundations 837 Figure 244. Geological section of the Champs de Mars 838 Figures 243 and 246. Foundation for a truss girder 839 Figure 247. Elevation of one of the principal truss girders 840 Figures 248-231. Sections of the great truss girders 841 Figures 232-254. Sections of the girders 842 Figures 255-257. Purlin ; elevation and sections ' 844 Figures 258-261. Rafter, rafter end, and sections A and B 845 Figure 262. Section of rafter 846 Figure 263. Method of erecting a great truss girder employed by the Fi ves- Lille Co 847 Figures 264 and 265. Elevation and plan of the foot of a great truss 849 Figure 266. Special arrangement of the pulleys for lifting the foot of the girder ... •. 850 Figure 267. Scheme adopted by the Fives-Lille Co. for erecting the rafters and purlins 850 Figures 268 and 269. Method of holding and rolling the purlins on the girder? 852 Figure 270. Lowering a purlin 852 Figure 271. Scaffolding for erecting the great truss girders ; Cail & Co. . 853 Figure 272. Upper platform of the rolling scaffolding 854 Figure 273. Cail & Co.’s method of erecting the purlins 855 Figure 274. Cupola of the Machinery Hall vestibule ; transverse section . . 857 Figures 275 and 276. Scaffoldings used in erecting the vestibule of Ma- chinery Hall 858 Figure 277. Longitudinal fagade of the side galleries 859 Figure 278. Transverse section through the crown of the arch 860 Figure 279. Lateral view of the side galleries from the principal nave. .. 861 Light-houses. Figures 280 and 281. Section and elevation of the Planier Light-house.. . 865 Figure 282. Iron light-house at Port Vendres 868 Figure 283. Lodging room of Port Vendres Light-house 869 Figure 284. Hyper-radiant apparatus for the new light-house at Cape Antifer, near Havre 871 Figures 285 and 286. Apparatus lighted with petroleum oil 873 Figure 287. Regulating brake and indicator of stoppage 874 Figures 288 and 289. Lamp maintaining the oil at a constant level 876 Figures 290 and 291. Bifocal apparatus for an electric light-house 877 Figures 292-294. Electric regulators and indicators 880 Figure 295. Light -house at Belle Isle, with acoustic apparatus 882 Figure 296. Apparatus for lighting beacon towers with gasoline 884 Graphic method of quadrature. By M. Ed. Collignon. Figure 297. Application to trapezoids 885 Figure 298. Application to trapezoids 886 Figure 299. Transformation of rectangles 887 Figure 300. Quadrature of curves 887 REPORT ox BY WILLIAM WATSON, Ph. D., Fellow of the American Academy of Arts and Sciences; member of the National Academy, Cherbourg; of the French Society of Civil Engineers; of the Prussian Society of Industrial Engineers; of the American Society of Mechanical Engineers ; of the American Society of Civil Engineers; late U. S. Commissioner to the Vienna Exposition; member of the International Jury of the Paris Exposition of 187S, etc. 543 WEIGHTS AND MEASURES. CONVERSION OF FRENCH WEIGHTS AND MEASURES INTO THEIR ENGLISH EQUIVALENTS. Measurements of length. French. British. Millimeter . . Meters. 0.001 0.01 0.1 3. 937 inches. 1 1,000 0. 62138 mile. Measurements of surface. French. British. Square meters. 0.000001 0.0001 1 10,000 0.00155 square inch. 0. 155006 square inch. 10.7643 square feet. 107,643 square feet =2.47114 acres. Measures of volume. French. British. Cubic meter. 0.000000001 1 0‘. 0000610271 cubic inch. 35. 3166 cubic feet. Measures of capacity. French. British. 1 liter . . . | 61. 0266 cubic inches. . 0.220215 gallon. Weight. French. , British. 1 kilogram. 2,20«i2 pounds. 1 Measure of work . — 1 kilogramineter =7.23314 foot-pounds. Money .— 1 franc=$0.194 gold. H. Ex. 410 — vol iii 35 545 TABLE OF CONTENTS. Page. Introduction 551 PART I.— RIVERS AND CANALS. Chapter I.— Hydraulic canal lifts at Les Fontinettes and La Lou- viere 552 Les Fontinettes lift — Introduction — Principle of the lift — Description of the works — The troughs — The pistons — The ] tresses — The guides — The machinery (pistons and pumps) — Method of working — Time required for an up and down motion — The towers — Method of erecting the presses and pistons — Cost — Summary — Acknowledg- ment. La Louviere lift — General remarks — The presses — Tests of the mate- rials — Precautions against freezing — Improvements proposed — Cost — Summary, Chapter II. — The movable dam at Suresnes on the Seine 564 General description — Frames — Panels — Cost. Chapter III. — Marly dam on the Seine 570 General description — Flooring — Frames — Panels — Cost. Chapter IV.— The new lock at Bougival and its hydraulic oper- ating appliances 572 Location — Motive power — New locks — Gates — Hydraulic machinery — Protection against frosts — Operating apparatus — Hydraulic cap- stans — Advantages of the system — Cost —Conclusion. Chapter V.— New movable dam at Poses on the Seine 588 Introduction — The curtains — The suspending bridge — The hoisting bridge — New principles — Depth of foundation — The flooring — The frames, and their method of suspension — Footbridge — Method of working — Construction — Cost. Chapter VI. — Villez movable dam on the Seine 606 System of closing — Frames — Method of opening. Chapter VII.— Movable fish way erected at Port-Mort Dam on the Seine 610 Chapter VIII. — Torcy-Neuf Reservoir for feeding the Central Canal 612 Generalities — The dike — The gate tower — Sluices — Guard lock — Cost. Chapter IX. — The new high lift locks on the Central Canal 619 Description — Fontaine cylindrical sluice — Lock gates — Time of lock- age — Cost. Chapter X. —Cable towage for boats on canals and rivers 625 Difficulties of cable towage — Systems adopted — Passage around bends — Method of attaching the boat to the cable — The grip — Length of circuit — Cost. 547 548 CONTENTS, Page. Chapter XI.— Towage by a submerged chain, with a fireless engine. 631 Chapter XII. — System for supplying the canal from the Marne to the Rhine and the Eastern Canai 635 Chapter XIII.— Oscillating bridge over the Dames Canal Lock 638 Chapter XIV. — Balanced gates at the place where the Rhone and Cette Canal crosses the Lez River 638 Chapter XV.— Braye-en-Laonnois Tunnel ". 642 Geological section of the ground — Use of compressed air — Accidents by fire — Accessory constructions. Chapter XVI. — Navigation of the Seine from Parls to the sea.... 649 Chapter XVII. — Embankment works for the improvement of the tidal Seine 651 Depth of water — Improvements — Alluvial land — Results. Paper by Prof. Vernon-Harcourt on the principles of training RIVERS THROUGH TIDAL ESTUARIES 653 Introduction — Conflicting opinions respecting methods — Investigation about the Seine estuary— Prof. Reynolds’s working model of the Mersey estuary— Model of the Seine estuary — The arrangements for imitating the tidal and freshwater flow — Trials of various gran- ular substances for the bed of the estuary in the model — Results of working with Bagsliot sand — Experiments with training walls introduced in the model — Principles deduced from the experiments. PART II.— TIDAL. COAST. AND HARBOR WORKS. Chapter XVIII.— Calais Harbor works 670 History — Sluicing basin — Docks — Improvements — Northwest dike — Use of water jets in driving piles — Outer harbor quays — Foundation of the quays by the system of water jets — Dock locks— Swing bridges — Hydraulic machinery for operating the locks and bridges — Quays — Graving dock — Barge dock. Chapter XIX.— The new outer harbor at Boulogne 687 State of Boulogne Harbor in 1878 — Project for a deep-water harbor — Work done up to 1889 — Description of the dike — Results obtained — Further improvements. Chapter XX. — Port of Havre— The Bellot Lock 694 Iron swing bridges — Lock gates — Hydraulic apparatus — New iron dock sheds — Cost. Chapter XXL — Port of Havre — Iron wave-breaker on the break- water on THE SOUTH SIDE OF THE OUTER HARBOR 700 Chapter XXII. — Canal from Havre to Tancarville — Single gate of the Tancarville Lock 702 Chapter XXIII. — Slipway built by the chamber of commerce at Rouen FOR THE REPAIR OF SHIPS 704 Chapter XXIV.— Port of Honfleur 708 Sluicing Basin — Method of closing the sluicing lock — Lock gates — Weir for feeding the storage basin — Description of the weir gates. Chapter XXV. — Port of Honfleur — Siphons between the storage BASIN AND THE FOURTH DOCK — AUTOMATIC SIPHONAGE 715 Chapter XXVI. — Traversing bridge on the dock locks at the port of St. Malo-St. Servan 718 Position and general arrangements— The lifting press — The recuper- ator — Operation — Weight and cost. CONTENTS. 549 Page. Chapter XXVII.— Hydraulic works and pneumatic foundations at Genoa 722 Dry docks and accessory works — The Quai des Graces — Character of the foundation — New method adopted for the foundation — Caissons for blasting out the rocks — Boring apparatus — Movable caissons for the construction of the quay walls — Description of the lock for admitting and removing material — The great floating caisson and its mode of working— Supply of compressed air, etc. — Iron centers for the arches of the Quai des Graces. Chapter XXVIII. — Port of Rochelle— Foundation of the jetties at La Pallice 736 Process adopted for the construction of the blocks — Description of the caissons and air locks. Work in the caisson — Displacement of the caisson — Access to the caisson — Removal of the submarine rocks — Cost. PART III.— BRIDGES AND VIADUCTS. Chapter XXIX.— The new steel bridge at Rouen on the Seine 745 Chapter XXX.— Reconstruction of the roadway on the suspension bridge at Tonnay-Charente— Alternately twisted cables.. 748 Chapter XXXI.— The lifting bridge at La Villette, Paris 752 Chapter XXXII.— The Garabit Viaduct 756 History — Description — The horizontal girders — The roadway — The arch — The iron piers— Principal dimensions — The stresses — Erec- tion of the iron work — Methods of raising the pieces — General information — Cost. Chapter XXXIII. — Gour-noir Viaduct 767 Chapter XXXIV.— Viaduct over the river Tardes ' 769 Chapter XXXV.— Consolidation of the side slopes at LaPlante 771 Chapter XXXVI.— Tunnel through Cabres Pass on the railroad from Crest to Aspres-les-Veynes 773 Chapter XXXVII. — Cubzac bridge over the Dordogne 775 The viaduct— The bridge proper — Method of launching by steam — De- tails of the machinery employed. Chapter XXXVIII. — The Crueize Viaduct 781 Chapter XXXIX.— Construction of the Castelet, the Laveur, and the Antoinette bridges 782 Description — Centers — Construction of the arch. Chapter XL. — The Ceret Bridge 789 Chapter XLI. — The Crossing of the Garronnf. at Marmande — The USE OF MASONRY CAISSONS 792 Chapter XLII. — Oloron Bridge upon the Gave d'Oloron Railroad from Pau to Oloron 796 Chapter XLIII.— The Gravona Bridge 798 PART IV.— CIVIL CONSTRUCTION AND ARCHITECTURE. Chapter XLIV.— Specimens of iron construction in Paris 801 Introduction — Borings — Zschokke’s bell caisson — Foundations — Iron work — Strength of the iron pillars and beams. Chapter XLV. — The Eiffel Tower 806 Introduction — Description of the proposed tower — Strength and sta- bility of the tower— Force of the wind— Different hypotheses 550 CONTENTS. Page. Chapter XLV.— The Eiffel Tower— C ontinued. adopted — Overturning moment —Anchorage —Deflection —Resis- tance of the tower against the wind— Calculation of the dimen- sions of the uprights— Construction— Situation — Borings — Use of compressed air— Foundations— Description of the iron work— De- tails of the foundation— Lightning conductors — Erecting scaffold- ings — Erecting cranes — Method of raising the cranes — Erection of the first and second stories — Erecting cranes above the second story — Method of shifting the crane — Protection of the workmen — Arrangement of the second and third stories — Staircases and eleva- tors — Time of ascent — Verification of the verticality of the tower — Uses of the tower — Strategical operations — Names of eminent men of science upon the tower — Statistics — Cost — Montyon prize in me- chanics awarded to M. Eiffel — Acknowledgments— Opposition en- countered by M. Eiffel in the erection of the tower. Chapter XLVI. — The Machinery Hall 832 Introduction — The Osiris prize — Popular estimate of the machinery hall — Extracts from specifications — Foundations — Description of the principal truss girders or arched ribs — Purlins and rafters — Erection — Method adopted by Fives-Lille & Co. — Method of raising the purlins and rafters — Weight — Method of erection adopted by Cail & Co. — The great vestibule — The erecting scaffoldings — The lateral galleries — Construction of the gables — Weight — Cost — Acknowledgments. PART V.— LIGHT-HOUSES. Chapter XLVII.— Planier Light-house 864 Chapter XLVIIL— Iron light-house at Port Vendres 867 Chapter XLIX. — Apparatus 2.66 meters in interior diameter called hyper-radiant, for lighting Cape Antifer 870 Chapter L. — Improvements in the apparatus in light-houses using mineral oil 872 Optical apparatus — Spherical reflector — Clockwork — Automatic brake and regulator — Electrical indicator of the stops of the machine — Constant level lamps. Chapter LI. — Improvements recently made in electric light-houses. 876 Bifocal apparatus — Motors and connections — Magneto-electric ma- chines — Working of the machinery — Results — Electric regulators and indicators — Cost. Chapter LII. — Acoustic signals in connection with electric light- houses 881 Chapter LIII.— The illumination of isolated buoys and beacons by MEANS OF GASOLINE 882 The apparatus — Burners — Properties of petroleum products — Arrange- ment of the reservoirs — Success — Cost. Chapter LIV.— Graphic method of quadrature 885 By M. Ed. Collignon, Chief Engineer of Roads and Bridges. CIVIL ENGINEERING, PUBLIC WORKS, AND ARCHI- TECTURE. By WILLIAM WATSON, Ph, D. INTRODUCTION. The information contained in this report is derived from official sources. Most of that relating to the public works of France has been obtained from the notices and documents collected by direction of the minister of public works, and exhibited in a special pavilion erected for the purpose. For a lai'ge number of stereotyped illustrations of these works I am indebted to the administration of roads and bridges, through the courtesy of M. Collignon, inspector of the school of roads and bridges. I wish also to express my obligations to M. Schwebeld, the accomplished librarian of the school, and to M. Boulard, the superintendent of the pavilion of public works, for explanations and valuable suggestions. For the information and drawings relating to the port of Genoa and the submarine work of the outer harbor of La Pallice, I am in- debted to the contractor, M. Terrier, of the firm of Zschokke & P. Terrier. To Mr. L. F. Vernon-Harcourt for his paper on the training of rivers through tidal estuaries. To MM. Eiffel and Nougier for the descriptions, pamphlets, pho- tographs, and prints relative to the Eiffel tower and the Garabit via- duct. To M. Contemin and his assistant, M. Groclaude, for information, and drawings relative to machinery hall. To M. Baudet for much information concerning the civil construc- tions described, including portions of the machinery hall, which were erected by him, as well as the lock gates and dock sheds at Havre. A model of one important work, viz, the Forth bridge, was shown at the exhibition; this bridge has since been successfully completed and may justly be considered the greatest triumph of engineering skill. An elaborately illustrated account of this structure has been published in Engineering, and it has not been thought best, for this reason, to enter upon its description here, as the author had no infor- mation concerning it that was not accessible to the public. 551 PART I -HYDRAULIC ENGINEERING-RIVERS. AND CANALS. Chapter I. HYDRAULIC CANAL LIFTS AT LES FONTINETTES, FRANCE, AND AT LA LOUVIERE, BELGIUM. TheNeufossd Canal unites the Aire Canal with the rivers Lys and Aa. It connects Dunkirk, Gravelines, and Calais with the system of internal navigation, and has an annual traffic represented by 13,000 boats. The Fontinettes locks, situated on this canal at Arques, near St. Oiner, consist of a chain of five successive locks surmounting a dif- ference of level of 13.13 meters. The time consumed in passing through these locks often ex- ceeded two hours; the system of crossing was consequently aban- doned, and one day the locks were used for ascending boats and the next for those descending. Much time was thus lost, involving con- stant crowding, and it was easy to see that the capacity of the locks would soon be reached. Again, as the Fontinettes locks did not ad- mit boats of more than 34.80 meters in length, they could not accom- modate those of 38.50 meters, carrying loads of 300 tons, which were in use on the northern canals. (2) To remedy this deplorable situation the Government ordered the construction of an hydraulic lift by the side of the Fontinettes locks, and similar to that in use at Anderton in England, on the Trent and Mersey Canal, which accommodates small boats of from 80 to 100 tons. The Government wished thus not only to improve the passage at Fontinettes, but also to try the experiment of raising boats of 300 tons burden by an hydraulic lift. (3) Principle of the lift . — The lift, properly so called, consists of two iron troughs containing the water in which the boats float. Eacii trough is bolted at its center to the head of a piston, or ram, which works in an hydraulic press set up in a basin. The two presses communicate by a pipe containing a valve serving to cut off, at will, communication between the cylinders. We thus have an hydraulic balance, and it is sufficient to give a certain surcharge of water to one of the troughs when the valve is opened, in order that one trough shall descend, and in doing so raise the other. Besides, the weight of the trough does not vary, whether it contains a boat or not, provided the water in it stands at the same level in both cases. 552 Civil Engineering, etc.— PLATE I. GENERAL VIEW OF THE HYDRAULIC CANAL LIFT AT LES FONTINETTES. 554 UNIVERSAL EXPOSITION OF 1889 AT PARIS. IT rWi " i Am Fig. 2.— Hydraulic lift at Ties Fontinertes. Longitudinal section along the axis of the trough. A, canal bridge ; B, movable trough ; C, pistons ; D. great presses ; H, frames supporting the lifting gates ; I, guides ; K, towers ; L, lookout cabin : M, machine house ; Q, service bridge ; S, capstan. Paris Exposition of 1889— Vol. 3. Civil Engineering, etc.— PLATE II HYDRAULIC CANAL LIFT AT LES FONTINETTES. VIEW OF THE TROUGH BASIN. CIVIL ENGINEERING, ETC. ooo (4) Description of the works . — A cut-off was made in the right bank of the Neu fosse Canal parallel to the Fontinettes locks, with a depth of water 2.20 meters and a width at the bottom of 17.95 me- ters. It is provided with a guard lock 6 meters wide at the junction of the excavation and embankment, and it crosses the Boulogne and St. Omer Railroad by an iron aqueduct divided into two independent lines, A A, each with a span of 20.80 meters. Immediately below this point the lift is placed. (Fig. 1.) A general view of the lift is given in Plate I. In the foreground is seen the iron lattice bridge over the two branches of the canal containing the lift. Immediately behind is the lower iron frame supporting the downstream gates; the trough on the right is raised; on the right and left are the towers with their iron guides to steady the trough in its ascent and descent. Behind the first tower, on the left, is the machine house containing the accumulator, the turbines, and the feed pumps; on the top is the lookout cabin containing the levers for opening and closing all the valves used in operating the lift. Still farther in the rear are the supports for the upstream gates, also containing the hydraulic mov- ing apparatus. Below, in the rear, is the iron girder bridge carrying the canal over the Boulonge and St. Omer Railroad, resting on the massive abutment. At the extreme right is the original canal lead- ing to a flight of five consecutive locks. Plate 1 1 shows the trough basin, giving a view of the trough as seen from beneath when it is raised, and of the parts of the structure which are then below the trough. It exhibits the junction of the square head of the ram with the trough bottom and the details of the construction of the latter. On the side of the house is seen the guide; beyond is the gate with its lifting chain and guide pulley, surmounted by the iron lattice supports. On the left side is a little centrifugal pump for draining the trough basin. (5) The troughs . — Each movable trough, B, is 40.55 meters long and has a working length of 39.50 meters. It is formed of two girders 5. GO meters apart, 5.50 meters in depth in the middle, and 3.50 me- ters at the extremities, not including the angle irons. These girders, carrying the corbels supporting the footbridge, are united by cross girders 0.525 meters high and 1.50 meters apart. The four middle transverse girders are 1.50 meters high; to these the piston head, hollo'vved out for this purpose, is attached by strong brackets, thus forming a rectangle 3.50 by 3.10 meters with a border 0.010 meters thick. The minimum depth of the water in the troughs is 2. 10 meters; the ends are closed by lifting gates. The troughs are lodged at the bottom in a dry masonry basin below the level of the lower bay, which is divided into two compartments by a wall 5.20 meters wide; each compartment has its lower entrance closed by a gate at the ex- tremity of each aqueduct. 556 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (G) The pistons . — The pistons are cast-iron plungers 17.13 meters long, 2 meters in diameter, and 0.07 meter thick; they are formed in sections 2.80 meters long flanged on the inside, united by bolts and made water-tight by a ring of sheet copper inserted between each flange. If i B 1 JJ Fig. 3.— Cross section through the transverse axis of the Hydraulic lift at Les Fontinettes.— Geo- logical section: 0 ravel with smooth stones; sand; fossil shells; broken tufa; compact tufa.— B B, movable troughs; C C, pistons; D D, great presses; E E. supply pipes; F, connecting valve; 1 1 1 1, guides ; KKK. towers ; I., lookout cabin; PP, compensating reservoirs. (7) The presses . — The great presses are 15.082 meters high and 2.078 meters in diameter. They rest upon masses of cement bdton at the bottom of the pits, which are 4 meters in diameter and tubbed CIVIL ENGINEERING, ETC. 557 with cast iron. The presses themselves are made up of rolled weld- less steel hoops 0.155 meter wide and 0.00 meter thick, stepped into each other at half thickness, with a joint 0.005 meter high, and made water-tight by a copper lining 0.003 meters thick. Each cylinder is stiffened by vertical angle irons, fastened to a hexagonal framing below the press, and above to a collar surround- ing the cylinder. Four crossbeams supporting the flooring, and resting upon the tubbing of the pits, complete the system. The bot- tom of each press is of armor plate 2.25 meters square. The joint between the piston and the press is formed by an India- rubber band, lined with sheet copper and lodged in an annular recess made in the cylinder cover; this lining is kept in place by a bayonet attachment. , (8) The presses communicate by an iron pipe 0.25 meters in diameter inside, starting from the bottom of eacli cylinder and ascending the corresponding pit; the pipe has a horizontal branch at the bottom of the basin between the two pits and contains a valve in the middle. This branch has also tubes connecting with two dis- tributors, by means of which water may be forced under pressure into either press, or allowed to escape therefrom. (9) Guides . — The troughs are guided on the upstream end and in the middle. The upstream guides are fixed to the downstream pier of the aqueduct, which forms the lift wall. The center guides, D D, which are the most important, rest against three massive square towers. They consist of strong steel shoes attached to the troughs and clasping the cast-iron guide bars. The downstream ends are not guided. (10) The engineer in the valve-house, L, at the top of the central tower directs the whole apparatus, opens and closes the connecting valve between the presses, and the valves of the distributors. Access to this house is afforded by the tower staircase or by a footbridge from the top of the lift wall. (11) The side towers contain wrought-iron cylindrical reservoirs 2 meters in diameter — equal to the exterior diameter of the pistons. Each of these compensating reservoirs, as they are called, can be put into communication with the corresponding trough by a jointed pipe. (12) When one trough is raised to the end of its course there is a play of about 0.045 meter between its upstream extremity and the downstream end of the aqueduct connecting with it. At the moment of raising the gates to allow a boat to enter or to pass out of a trough the joint is made, by an India-rubber hose running round the end of the aqueduct and protected by springs. This hose is inflated with air at a pressure of l£ atmospheres. Little valves inserted in the gates permit this space (between the gates) to be filled with water before making the connection. The same arrangement is made for the lower bay joint. 558 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (13) Porticos constructed on the lift wall, and also on the tail wall, have, on their tops, hydraulic apparatus for lifting the gates. The gates, which are balanced to a great extent by counterweights, allow, when raised, a free height of 3.70 meters above the level of the water. Below the lift, a footbridge, Q, connects the two banks with the central masonry wall. (14) The machinery (PI. Ill) placed in a building, M, between the two compartments of the dry basin on the upstream side of the cen- tral tower, consists of two turbines driven by the water of the upper bay, brought into a tank between the two lines of the aqueduct. One turbine of 50 horse power drives four double-acting force pumps coupled together two and two, and supplying an accumulator of 1,200 liters capacity. The other 15 horse-power turbine drives the air compressor for the inflation of the joining hose, and also a cen- trifugal pump which serves to keep the trough basins clear of water, whether from leakage or false maneuvering. A little steam engine works the pump when the upper bay is not in use. (15) The weight to be raised, including a piston, a trough, the water, and a boat floating in it, amounts to about 800 tons; the pressure in the presses is, therefore, about 25 atmospheres. But the accumulator has been loaded to 30 atmospheres to make sure of the efficient working of the presses for lifting the gates. The compensating reservoirs were intended by the authors of the project to reduce the consumption of water, but it has not been thought best to use them. (10) Method of ivorking the lift . — The lift is worked as follows: One of the troughs being raised to the height of its course and con- taining a depth of water 2.40 meters, the joint is made by opening the cock admitting compressed air into the hose running around the face of the end of the aqueduct. Then the trough and aqueduct bridge are hooked together, and at the same time the space between the gates is filled by means of a little valve. The two gates are then raised together by means of a counterpoise and the hydraulic appa- ratus; a boat is hauled into the trough, then the gates are lowered and unhooked, the valve is closed, and the air in the rubber hose allowed to escape. During this time similar operations have taken place below; the other trough being at the end of its course, resting on wooden blocks and containing water 2.10 meters deep. The upper trough has thus a surcharge of 0.30 of a meter in depth, corresponding to about 64.6 tons. The connecting valve between the presses is then opened and one trough descends while the other rises. The motion is stopped by closing the connecting valve when the level in the ascending trough is 0.30 of a meter below that of the upper bay. The descending Paris Exposition of 1889 — Vol. 3. Civil Engineering, etc. PLATE III. HYDRAULIC CANAL LIFT AT LES FONTINETTES. VIEW OF THE PUMPING MACHINERY. CIVIL ENGINEERING, ETC. 559 trough has also its level 0.30 of a meter above the level of the lower bay. The joints are formed, and the gates lifted, slightly at first, then completely. The upper trough takes its surcharge for the following operation while the lower one gives up its water ballast to the lower bay. The boats can then be hauled out and replaced by others. The position of a trough may be corrected either before or after the opening of the lifting gates. It is sufficient for this purpose to move the distributor valves so as to allow water to escape from the press or to introduce water under pressure from the accumulator into it. ' Also safety valves are introduced, opening automatically, and thus preventing the trough from rising too high, which might be dan- gerous. (17) At the beginning of the operation, the press of the upper trough contains 41 tons of water more than that of the lower. The force producing the descent attains about 10G tons. This force pro- gressively diminishes, since the water in the first press passes gradu- ally into the second, and at the end of the operation the force is only 24 tons; this is necessary to overcome the friction and passive resist- ances. This force tvould be in reality only 12 tons if the connecting pipe was entirely free, but it was thought best to reduce the section by valves and thus regulate the apparatus, in order to avoid either an excessive velocity or a premature stoppage in case of error in taking the surcharge. As we see, the initial force diminishes and the motion slackens continuously, so that each trough comes to the end of its course with nearly no velocity. (18) The actual time of the up and down movement of a troxigli is on an average 2G minutes, made up as follows: Minutes. Entrance of the boat and closing of the gates * 8 Ascent and descent of the troughs f 5 Correction of the position of the troughs 3 Opening the gates and hauling out the boats 10 Total “ 26 When the hydraulic capstans are set up to hasten the entrance and exit of boats, which is now done by men, this time will be reduced to 20 minutes, and six boats per hour will be passed. The works were begun at the end of 1883. The first attempts to work the lift took place in November, 1887, and it was opened for traffic the 20th of April, 18^8. *This is a mean of 4,769 operations. t This time would have been reduced to 3 minutes if the section of the conduit between the presses had not been reduced as a precautionary measure. 560 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (19) The towers . — The slightest movement of the towers would affect the vertically of the guides ; they were accordingly built on piles. (20) Erection of the presses . — Ingenious devices were adopted to set up the presses and pistons. The troughs were put together upon scaffoldings 7 meters above bottom of the basin, leaving the central portion above the pits open. In this position the girders of the troughs served to support a trav- eling crane which carried the pieces to be lowered into the pits. Each press was erected as follows : The hexagonal framing hav- ing been placed, the bottom of the press with the first steel rings and the lower elbow of the connecting pipe were lowered, the whole having been lined with copper, the latter projecting beyond the rings. A copper collar 2.44 meters high, made in the workshop, was then riveted and soldered to the lining already placed so as to form on the exterior a regular cylindrical surface. The collar had a di- ameter very slightly less than the interior diameter of the rings. The latter were threaded on to the collar to a certain height, and then a new collar was placed, and so on. The presses being set up, they were tested by a hand pump up to 54 atmospheres. The presses were found perfectly tight, and the result of the test was to press the copper lining exactly against the steel rings. (21) The pistons . — After this trial the pistons were set up as fol- lows: Each press was filled with water and the connecting pipe closed by a plug having in it a three-way cock. The first section of the piston was placed so as to be supported by the water and project out of the press. The second section was then placed and the joint carefully made. By allowing a small quantity of water to escape from the cylinder the two sections were lowered so as to put on the third, and so on. If one of the joints was not tight it was discov- ered immediately by means of the hand pump, the piston was raised, and the defect corrected. When the piston was in place the central portion of the trough was completed. Then the piston head was raised so as to bolt it on to the cross girders. The whole was then raised slowly by the hand pump and the trough lifted from its scaffolding, which was then removed. (22) Cost . — The cost was nearly as follows: Francs. Lands and buildings bought 165, 017. 32 Foundation (by compressed air) of the lift wall 97,000.00 Earthwork and masonry 583,492.71 Ironwork, including the sinking of the pits 831,102. 00 Salary and patent royalty to Mr. Edwin Clark 47, 670. 00 Sundries 145,717.97 Total..., 1,870,000.00 CIVIL ENGINEERING, ETC. 561 The location of the Fontinettes lift was necessarily fixed; conse- quently the purchase of lands and buildings of great value, the ex- pense of making a cut-off in a high filling, of crossing a railroad track, and of laying foundations under great difficulties, could not have been avoided; besides, the Government made its contract with Cail & Co. when the price of iron was very high. Considering the circumstances, it may be affirmed that if a similar lift were to be constructed on a new canal, the total expense would not exceed 1,300,000 or 1,400,000 francs. (23) The plans for the earthwork and masonry were prepared by Messrs. Gruson, chief engineer, and Cetre, assistant engineer, who directed the works. The contract for the metallic portion was awarded to Cail & Co., who intrusted it to M. Barbet, their chief engineer. Most of the work of erection was directed by M. Ballon. SUMMARY. Les Fontinettes lift — Neufosse Canal , France. Trough — Length meters.. 39.50 Breadth do ... . 5. 60 Depth of water do 2. 10 Press — copper internal cylinder with exterior weldless steel hoops. Thickness of copper cylinder meters. . 0. 003 Thickness exterior steel hoops do . . . 0. 060 Length of press do. ... 15. 682 Length of stroke (height of lift) do. ... 13. 13 Pressure in the press atmospheres. . 25 Ram or piston — Thickness of cast iron meters. . 0.070 External diameter do.... 2.00 Total weight lifted, including water, trough, and ram, 800 tons. Equivalent to a pressure of 25 atmospheres. The contents of one stroke, in water tons. . 41 Equivalent to a surcharge on the trough of meter. . 0. 20 Actual surcharge used tons. . 64. 6 Equivalent to a depth of water of meter. . 0. 30 Size of boats lifted tons. . 300 Actual time of lift minutes. . 5 Acknowledgment . — I wish in this connection to express my indebt- edness to M. Gruson, chief engineer of roads and bridges, for the in- formation concerning this interesting subject as well as for the three figures which accompany it. THE LIFT AT LA LOUVIERE. (24) This lift is situated in Belgium at La Louvifere station on the railroad between Mons and Namur, on what is called the Center Canal, which, when finished, will unite the Mons and Conde Canal H. Ex. 410 — vol hi 3G 562 UNIVERSAL EXPOSITION OF 1889 AT PARIS. with a branch ( i . e., the Houdeng-Goegnies) of that from Charleroi to Brussels. The canal itself is only 15 kilometers long, but the chief difficulty is in a section of it 7 kilometers long, from La Louvi^re to Thieu, with a fall of 66.19G meters, which it is proposed to surmount by the construction of four lifts. (25) The first lift already completed is in the commune Houdeng- Goegnies, not far from La Louviere, so that it is sometimes called the Houdeng lift. The masonry work of this lift was begun on the 15th of May, 1885, and the ironwork was finished in the beginning of 1888. It is not proposed to consider here the motives which induced the Belgian Government to adopt the lift system, nor to repeat a detailed description of it. The two lifts of Fontinettes and La Louvikre are similar in all their essential parts; they only differ in their dimen- sions, their weight, and in some details of construction, which we now propose to notice. (2G) The presses . — The only real difficulties met with were in the construction of the presses for raising the troughs. These are the most important and dangerous parts of the system. Upon them the stability and equilibrium depend ; they must have unusual dimen- sions; it takes a certain amount of audacity to put a load of 2,096,000 kilogrammes upon two presses, requiring their interior diameters to be 2.06 meters each, with a permanent tension of 34 atmospheres. (27) We have already seen how the problem was solved in France. In Belgium, after many experiments, it was decided to form the presses in cylindrical cast-iron sections 0.10 meter thick, 2.0G meters in diameter, and 2 meters high, around which weldless steel coils 0.05 meter thick and 0.152 high are shrunk on so tightly as to prevent the cast iron from having, at the interior concave surface, a stress of more than 1 kilogram per square millimeter with a tension of 34 atmospheres inside the press. (28) Tests of the iron and steel . — One of the sections broke on trial at a pressure of 146.5 atmospheres. The steel has a tensile strength of 46.87 kilograms per square millimeter with an elongation of 25 per cent at the point of rupture. The cast iron, run into little bars, had a tensile strength of 17.53 kilograms and a resistance to compression of 73.49 kilogrammes. Finally, and this is the most important test, a cast-iron section hooped with steel, after a series of trials going up to 200 atmospheres, broke at 265 atmospheres, the cast iron only having given way with- out producing a rupture or any alteration in the steel hoops. We may therefore consider the resistance of the presses at least eight times superior to the permanent tension to which they are exposed. The cast iron here plays the part of a tight lining only, and it seems more simple and rational, at least in theory, to replace it with CIVIL ENGINEERING, ETC. 563 copper a few millimeters thick, and depend wholly on the steel hoops for strength, as in the French lift. (29) The pistons — Each cast-iron piston has three parts ; the head, which supports the trough, and is 3.20 meters square, and 1.40 meters high ; the shaft, composed of 8 sections, each 2.13 meters high and 0.075 meter thick, bolted together; and the foot, which is a spherical segment 1 meter in height. (30) The communication between the presses takes place near the top through a flanged annulus bolted in between two segments, thus forming practically the strongest portion of the press, which is fed through a series of holes 0.05 meter in diameter made in the annu- lus ; the two distributing annuli are connected by a special pipe. It will be remembered that in the Fontinette lift the presses are connected at the bottom, thus requiring a pipe double the height of the pits. The spaces between the troughs and the aqueducts, above and below, are closed by metallic wedges lined with India rubber. Sets of hydraulic apparatus driven by an accumulator containing water under a pressure of 40 atmospheres drive these wedges, lift the gates of the aqueducts and troughs, and turn the capstans for hauling the boats in and out of the lift. Cost . — The cost of construction of La Louvi&re lift is as follows: Francs. Purchase of lands 11,273.00 Earthwork and masonry, including the tubbed pits and machinery houses 402,163.36 House for the engineers 26,891 . 68 Metallic portion, including the machinery 899,062:71 Patent rights, and salaries of L. Clark Stanfield, and E. Clark 65,586.61 Total 1,404,979.36 If we add the cost of journeys, plans, committees of consultation, and oversight, the sum will amount to at least 1,500,000 francs. (31) Precautions against frost . — During heavy frosts the troughs are both lowered, and the presses and pipes emptied. In the new lifts about to be erected by the Belgian Government all the pipes will be protected from frost by being inclosed in large masonry chambers in which fire can be kept; the same precautions are taken iu reference to the valves, the pumps, and the hydraulic machinery. (32) Conclusion . — The experience acquired and the observations made in the construction and working of this lift have suggested numerous and important improvements which will be introduced into the lifts now in process of construction. The whole apparatus will be considerably simplified. The compensating reservoirs have been definitely abandoned, and the footbridges around the troughs dispensed with.* lie port of M. Duffourny. I 564 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The iron aqueducts uniting the upstream end of the canal with the troughs are replaced by masonry ones. The wedges are fixed with a possibility of adjusting the upper one by hand. The downstream guide is omitted, and every cause of accident due to the spontaneous action of water under pressure is carefully removed by taking care to move by hand the wedges and the hooking bolts of the gates. The operating levers worked by hand are interlocking, and abso- lute security results from the fact that an error in operating is me- chanically impossible. The bottoms of the basins have been raised considerably by giving a more natural form to the longitudinal trough girders, and the weight of all the movable parts of the system has been reduced by the substitution of steel for iron. A last improvement is the protec- tion of the pipes and valves from the action of the frost. SUMMARY. La Louviere lift, Canal du centre , Belgium. Trough : Length meters. . Breadth do. . . Depth do... Weight tons. . Draft of water meters. . Ram or piston — cast iron : Diameter meters. . Thickness do. . . Length do. . . Weight tons. . Press — cast iron, hooped with continuous steel coils : Internal diameter meters. . Thickness of cast-iron core do. . . Thickness of steel coils do. . . Length of press do . . . Length of stroke do. . . Weight of trough, water, and piston tons. . Equivalent to a pressure of atmospheres. . The contents of one stroke in water weighs .tons. . Working surcharge 0.25 meters do. . . Actual time of lift, from 2 to 3 minutes. Size of barges lifted tons. . Total time, including entering and departure of a barge in each direction, 15 minutes. 43.000 5.800 3.250 296 2.400 2.000 0.075 19.440 80 2.060 0.100 0.050 19.590 15.397 1,048 34 49.3 63 400 Chapter II.— The movable dam at Suresnes on the Seine. (34) The ueedle dam constructed at Suresnes in I860 assured a draft of water through Paris of 2.20 meters; to obtain one of 3.20 meters above Paris it was decided in 1880 to reconstruct the dam so as to have an additional fall of 0. 97 meters. CIVIL ENGINEERING, ETC. 565 The river Seine is divided at Suresnes into three branches by the Folies and Rothschild islands. The dam is built at the head of these islands and consists of three separate passes. Looking down the stream on the left is the navigable pass, 72.38 meters. To the right, between Rothschild and Folie islands, is the waste weir or intermediate pass, 62.38 meters; to the extreme right is the raised pass, 62.38 meters; the total length, 197.14 meters. Above and below each pass are the aprons marked R. Next to the navigable p'iss are the little lock, P, the old lock, A, and the great lock, G. On the left bank is the lockman’s house, E, and on each of the two islands houses, B B, for the “ bar ri agists ” or dam keepers. The rectangle in front of the navigable pass shows the location of the old dam, and the old weir extending from the end of Rothschild Island to the outer end of the rectangle. 566 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The normal fall is 3.27 meters. (35) The dam is closed by a method imitated from Poiree’s sys- tem of needle dams; Poirde's frames (fermettes), Fig. 5, have been retained, but with such modifications as were requisite to withstand the increased pressure due to the unprecedented difference of level. Number of frames. Height of frames. Weight of a frame. Cost. Meters. Kilos. Francs. Navigable pass 58 6. 1,800 1,500 Raised pass 50 5. 49 1,350 1,135 Waste weir 50 4.14 800 660 (35) Frames . — Each frame (Fig. 5) consists of a downstream and upstream upright, united by horizontal and diagonal bracing. These uprights, instead of being merely plates, are made up of channel iron put together so as to form (Fig. 6) box girders. These girders have the advantage of resisting equally well in the direction of the water pressure and in that at right angles, produced by raising or lowering the frames. To vary the resistance in the first direction it is only necessary to increase the distance between the channel irons; to vary it in the direction at right angles it is sufficient to increase the number of irons. The bracing consists only of channel irons having nearly the same dimensions as those of the uprights. The frames, 1.25 meters apart, are united by three distinct rails which serve to carry the hoisting windlass and the planks of the service bridge crossing all three passes. (30) Operations . — The difficulties in raising or lowering the frames are satisfactorily overcome by the use of Megy’s patent windlass. All the frames of the Seine pass are united by a continuous chain by means of link catches placed on their upper cross brace. The length of the chain between two successive frames is greater than the distance between the axes of rotation, so that six frames are lowered or raised like the sticks of a fan ; the chain is hauled in by a windlass placed on the abutment of the pass. By this system, having put the first frame in place, it is only nec- essary to haul in a short length of chain to bring the second into its upright position, and the operations of opening and closing the passes are almost reduced to the taking up or putting down of the rails and planks of the service bridge. At Suresnes the opening of the navigable pass, 72.38 meters in length, is accomplished in 3 hours, and the closing in 5 hours; al- though each of the fifty-eight frames weighs 1,800 kilograms. The following table indicates the diameter of the chains and the cost of setting up of three dams. . CIVIL ENGINEERING, ETC, 567 MOVABLE DAM AT SURESNES. 3 m ,700 Fio. 5. — Movable frame (fermette) of the navigable pass. Fio. 6. —Transverse section of the upstream upright. Fio. 7 —Transverse section of the downstream upright 0 10 568 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Power of windlass. Diameter of the chains. Total cost. Navigable pass Tons. 10 mm. 26 Francs. 9,400 Waste weir 4 17.5 5,400 Raised pass 6 21 6,600 (37) The flooi-ing, fixed in the masonry, has the peculiarity of hav- ing no portion hollowed out to receive the frame. The sill is placed at such a height as to protect the frame when lowered, but at a cer- tain distance from them it is united by an inclined plane to the row of cut stones containing the upstream axle bearing. These stones project a distance of 0.30 meter, and beyond them the flooring is horizontal. Hence no deposit can be formed to obstruct the lower- CIVIL ENGINEERING, ETC. f>69 ing of the frames. Iron sockets placed on each side of the frames allow the formation of a cofferdam in case of need, with the aid of a windlass, for the purpose of making repairs. (36) Panels . — The dam is closed both by M. Boult's panels and by IVr. Camera’s curtains. (The latter will be hereafter fully explained). M. Boule’s panels are of wood, 1.22 meters wide by 1.10 meters high, varying from 0.04 to 0.09 meter in thickness. A panel of 0.09 meter is placed between two frames of the navi- gable pass at the bottom, then one of 0.08 meter, followed by one of 0.07, 0.06, and finally one of 0.04 meter. (Fig. 8). The water flows over the tops of the panels, and the opening takes place in horizontal layers; the upper panels across the dam are first removed, then the second, the third, and so on to the last; the flow always passing over the top. This apparatus is strong, simple, and easily operated, for, as the panels are removed the head falls, and consequently the pressure diminishes, so that the effort to raise a panel under water is always slight, and about the same whatever height the dam may have. (37) Handling the jmnels . — The panels are handled by means of of a windlass with a long straight rack terminated by a hook and guided by the frames themselves. (38) Cost . — The works for the erection of the dam were begun in 1882, and finished in 1885, at a total cost of 2,799,958 francs, includ- ing those for the protection of the banks in the three passes, the earthwork on the islands, the storehouses and dwellings for the lockmen, etc. The dam, properly speaking, including the abutments, piers, floor- ing, and movable parts cost, per running meter — Francs. For the navigable pass (frames 6.01 meters) 12,262 For the raised pass (frames 5.49 meters) 10.817 For the waste weir (frames 4.14 meters) 7,727 Average cost for the dam per running meter 10,370 The following table indicates the weight and prices of the different panels : Thickness of panels. Weight. Cost. Meters. Kilos. Francs. 0.04 83 41.01 0.06 115 52.01 0.07 138 58.95 0.08 ... 147 80.40 0.09 ia? 70.84 Total for one span 664 283.21 The project was prepared and the works executed under the direc- tion of M. Bould, chief engineer, and MM. Nicou and Luneau, as- sistant engineers. 570 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Chapter III.— Marly dam on the Seine. (39) The old Marly dam which consisted of five piers and two abutments, supporting six spans of planks 5 meters long, with a cross section of 25 x 20 millimeters, very difficult to handle, and indeed often impossible in times of freshet, has just been replaced by a Poiree dam. that is, the piers have been replaced by iron frames like those of the movable dams; upon these frames panels, large and small, rest and slide, which are easily handled under all circumstances. But as this dam is situated in a branch of the Seine which is not navigable, and behind the sci'eens for protecting the water wheels which form the Marly machine, the frames are never lowered as in movable dams, for no boat ever passes through it; and as the screens protect it completely from ice, it is sufficient to vary the flow over the weir as the waters rise or fall. These frames being thus fixed, and incapable of being lowered, certain modifications in their construc- tion have been mad», economizing material used, and changing the system of attachment to the flooring, both of which have been here introduced for the first time. The dam is 36.15 meters wide and has a fall of 3 meters. The flooring is placed 0.20 meter above the lower bay. The frames are twenty -eight in number, 1.25 meters apart; the dam is closed by panels, large and small, sliding in guides formed by the upstream uprights of the frame, and handled by a windlass rolling on the service bridge. (40) Flooring.— The flooring. 12 meters long, between two rows of piles and sheet piling, is 3.75 meters thick, consisting of: (1) A layer of beton 2 meters thick, laid under water, and covering the heads of 210 piles, driven to consolidate the foundations; (2) of a mass of rough masonry 1.30 meters thick; (3) a hewn stone revetment 0.45 meter thick. The rear apron, 4.50 meters long, is formed of masonry blocks, 2.250 cubic meters, weighing about 5,000 kilograms each; and at the end of these blocks coarse riprap is placed. This dam was constructed by means of a cofferdam built above, having a fall of 3.20 meters. Below, the work was sheltered from little freshets by simply raising the inclosing walls, which were sawn away when the frames had been set up. (41) The frames . — The fixed frames are 3.80 meters high and 3 meters long at the base (Fig. 9). The upstream upright, inclined at an angle of 22° 30’, with the vertical, directs the resultant pressure towards a point exterior to the base but very near the downstream end; the overturning moment is nearly nothing, and the general action of the frame upon its fastenings is reduced nearly to a hori- zontal thrust. The pressure is transmitted directly to the apron by three inclined braces, which divide it between the different groups of fastenings, so that these fastenings only resist shearing. CIVIL ENGINEERING, ETC. 571 Nevertheless, to guard against the vertical tension from below up- ward the first anchorage consists of a great cut stone, attached to the mass of the apron by channel-iron plate bands and anchor rods 2.50 meters deep, with washers 0.40 meter in diameter. Each frame rests upon the horizontal surface of the apron, on its lower flange, forming a double T reversed, and strengthened by a plate, the whole having the form shown in Fig. 10. It is fastened by eight bolts divided into four groups, and a cast-iron shoe placed on the downstream side, fastened by three bolts 0.03 meter in diam- eter. Fig. 9. Fixed frame used in the Marly Dam. Fig. 10. Method of anchoring the frame. The total maximum pressure of 9,579 kilograms gives a horizontal component of 8,850 kilograms, and if we admit that the lower flange of the frame divides this effort equally between all the fastenings— which is a rational supposition in view of the situation of the braces, and the rigidity of the lower flange — we find that each bolt has a load of 805 kilograms, that is, a maximum load of 2.05 kilograms per square millimeter of section. The weight of each frame is G.35 kilograms. (42) The panels are 3 meters high vertically and 3.25 meters in the direction of the uprights of the frames. They are divided into four ranks, having the following heights, respectively, 0.89, 0.98, 1.09, and 0.32 meters. The last rank serves to regulate the fall. In each rank the thickness of the panel varies from the base to the summit, so as to avoid all useless weight. These panels can be handled from the upper service bridge by means of a windlass of 1,800 kilograms power, which can raise a 572 UNIVERSAL EXPOSITION OF 1889 AT PARIS. panel from the bottom or drive it back under a fall of 3.80 meters, a fall higher than would be possible under any circumstances. The upper panels are moved by a little crane of 300 kilograms power, more easily handled than the windlass. (43) Cost .— The cost amounts to 271,000 francs, as follows: Francs. Upstream cofferdam, 60 meters long, built in a fall of from 1.50 to 2 meters . 55, 000 Dredging foundations in the location of those of the old Marly machine . . 30,000 Wood and masonry work for flooring and abutments 133,000 Storehouse and removal of the cofferdam 24, 000 Iron frames', panels, windlass, etc 22,000 Total 271,000 Price per running meter, 7,490 francs. The work were directed by M. Boult?, chief engineer, and M. Jozan, assistant engineer. Chapter IV.— The new lock at Bougival and its hydraulic WORKING APPLIANCES. Looking up the stream on the right is the famous Marly machine, a collection of water wheels for supplying the city of Versailles with water; at right angles to it is the new dam, N, at Marly (see Fig. 11). A is its waste weir; on the left is Loge Island, on which a roadway is built at a reference, 26.80 meters above sea level, connected by a foot- bridge with the right bank. Next on the left is a great lock, G, con- necting the two pools, Bezons, 23.73 meters, and Andresy, 20.53 meters. To the left is the little lock, P. Two houses for the lock- men, E E, are situated, one on Loge and the other on Gauthier Island. (44) The work of constructing new locks at Bougival for the pur- pose of obtaining a draft of 3.20 meters between Paris and Rouen was begun in 1879 and finished in 1883. Two locks, side by side, have been built, one, 220 meters long and ■ 17 meters broad, for trains, and the other, 41.00 meters long and 80.20 meters broad, for isolated boats. Both locks accommodate boats drawing 3 meters. The fall is 3.20 meters. The length of the great lock was made 220 meters, instead of 140 meters the usual size on the lower Seine, in order that it might con- tain the largest trains which the towing company generally tows between St. Denis and Paris, that is to say, sixteen or seventeen barges and the towboat. (45) Motive power — All the apparatus of the locks except the gate sluices are worked by water power, from an accumulator loaded so as to produce a pressure of 00 atmosphei’es and supplied by pumps driven by turbines obtaining their power from the Marly dam. CIVIL ENGINEERING, ETC. 573 The motive for adopting this apparatus was the great traffic pass- ing through these locks, which are the most frequented, not only of the lower Seine, but of the navigable water ways of France. There passed in 1888 through the Bougival locks 23,230 boats, carrying 3,050,829 tons of merchandise. Before describing the new locks we must add that the old Bougival lock constructed in 1838 by M. Poirde has just been restored, giving a chamber 113.50 meters of available length and 12 meters wide, capable of containing six barges drawing 2.30 meters. 574 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (46) Netv locks . — The coping of the new locks is placed 1.G1 meters above the normal height of the upper bay, which is the height corre- sponding to the highest water safely navigable Avith the towboat. The gates, 12 meters wide for the large lock and 8.20 meters for the small, are of pitch pine with oak frames. Each pair of lea\ r es has four gridiron valves having a total section of 3.4;} square meters. Besides these valves, culverts, placed in the Avails on each side of the gate, fitted with gridiron sluices, have a total sectional area of 4.80 square meters for the large lock and 3.50 square meters for the small. The volume of Avater requisite for each lockage is, respectively, 13,800 and 1,750 cubic meters. (47) Hydraulic machinery. — The application of hydraulic poAver for working the neAv locks at Bougival according to the plans of M. Barret Avas decided on in 1879. The system includes: (1) The ma- chinery and accumulator; (2) the piping; (3) the hydraulic presses for moving the gates, cuh'erts, sluices, and capstans. The machinery and accumulator are placed in a building on the right abutment of the Marly dam and comprise: First. Tavo Fontaine-Baron turbines Avorked by the fall of the Marly dam which varies from 2.30 meters to 0.80 meter and gh'es under the least favorable condition 14 horse power. Second. Tavo sets of three single-acting plunger pumps dri\ r en by the turbines by means of beveled gearing, capable of making from twenty-three to forty-five strokes per minute and forcing into the accumulator from 1.372 to 2.205 liters per second. A pump is attached to each turbine to raise water for the tank on the first story, which supplies the Avater for the accumulator. * Third. An Armstrong accumulator of 700 liters capacity loaded for a pressure of 60 kilograms per square centimeter. Its stroke is 5 meters, and it is filled in from 4 to 9 minutes, The piping comprises the supply pipe from the accumulator to the hydraulic machinery on the lock Avails, and the pipe which returns the Avater to the feeding tank; so that the same water constantly cir- culates, except some slight losses which are made good by the pumps. The pipes are cast iron or drawn wrought iron; those Avhicli have to sustain pressure are tested up to a hydrostatic pressure of 110 kilo- grams per square centimeter. The head Avails are reached by means of siphons submerged in the gate chambers. The effective pressure in the pipes is transmitted to a distance of more than 600 meters from the accumulator Avithout loss of head on account of the slight flow and the small diameter of the pipe, which is only from 0.0G to 0.07 meter in interior diameter. 575 576 UNIVERSAL EXPOSITION OF 1889 AT PARIS. NEW LOCK AT BOUGIVAL. 1 Pil Fio. 13. —Machinery house and accumulator, horizontal section. 'Hk! 577 CIVIL ENGINEERING, ETC. LOCK AT BOUGIVAL. H. Ex. 410 — vol hi 37 578 UNIVERSAL EXPOSITION OF 1889 AT PARIS. LOCK AT BOUGIYAL. Apparatus for operating the lock sluices by hydraulic power alone. Fig. 15.— Vertical section. Fig. 16.— Elevation. CIVIL ENGINEERING, ETC. 579 LOCK AT BOUGIVAL. ApPARATVS FOR OPERATING THE LOCK SLCICES BY HYDRA L'LIC POWER ALONE. Fig. 17. -Horizontal section along A, B, C. D. (Fig. 13) Fig. IS.- Plan of the sluice. FIGS. 12, 13. 14 . — Machinery house and accumulator. a, Supply pipe from the tank to the pumps. b, Direct supply pipe for the pumps. c, Supply pipe from the accumulator to the presses. d, Return pipe. e, Waste valve regulated by the stroke of the accumulator. /, Lifting pump ; g. its suction pipe. Ii. Pipe supplying the accumulator. F. Filter: R, reservoir; i, float. k. Waste pipe: rr, stopcocks: s, safety valve. M, T. Punching machine and lathe. V, Turbine sluices. v, Emptying cock for the pipes. Figs. 15-18 .— Apparatus for operating the lock sluices. a. Frame of the cylinder for operating the sluices: b. Cylinder for operating the sluices: c, Differential piston; d. piston rod: e. air cock; //, Water cocks: g, gridiron sluice; li, sluice seat; j. Upper bearer; k, valve chest. 580 UNIVERSAL EXPOSITION OF 1889 AT PARIS. LOCK AT BOUGIVAL. Combined apparatus for operating tue lock sluices either by hand or by hydraulic power. Fig. *!. -Engaging gear CIVIL ENGINEERING, ETC. 581 LOCK AT BOUGIVAL. Figs. 13-23 . — Apparatus for operating by hand. A, Endless screw terminated above by a square head on which a strong kev, provided with handspikes, fits. B, Vertical cylinder for operating the abutment sluice. C, Worm wheel driven by the endless screw and driving the rack and pinion; E E, racks. F, Balance beam driven by the racks and united in the middle of the sluice. G, Rollers guiding the racks; P, counterpoise counterbalancing the endless screw to facilitate the working of the engaging and disengaging gear. Hydraulic apparatus for operating the lock gates. Fig. 24.- Valve chest, vertical section along I J (Fig 25). Fig. 25.— Horizontal section along K L (Fig. 24). a, Cast-iron frame; b, bronze valve seat; c, valve chest; d, D valve; e, valve rod; f, eccentric; g, eccentric rod having its vertical axle with a square end to fit the operating key; i, the stem of the stop valve, forming the valve itself: j, duct leading the water under the piston: k, exhaust; /, duct leading the water above the piston; m, supply pipe for the water under pressure. 582 UNIVERSAL EXPOSITION OF 1889 AT PARIS. LOCK AT BOUGIVAL. CIVIL ENGINEERING, ETC. 583 (48) Protection against frost. —In the winter, to avoid frost in the apparatus and in the pipes exposed to the air in short lengths, 6 or 8 kilogrammes of glycerine per cubic meter are added; this material has the advantage of lubricating the surface of the pistons, while chloride of magnesium, though cheaper, corrodes them and is hard to preserve on account of its deliquescent properties. When the apparatus is well guarded by manure, glycerine is only used when the temperature descends 7 or 8 degrees below freezing. (49) On the supply and return pipe four pieces of apparatus are placed for operating the gates of the large lock, each consisting of a horizontal cylinder (Figs. 20 and 27) oscillating around a vertical axis and having its piston attached to the upper transverse girder of the leaf, 2 meters from the heel post; this piston is called differential, because in one direction, the pressure being the same on the two faces of the piston, the motion is due only to the difference of the sections Fig. 28.— Transverse section through X Y (Fig. 27). Fig. 29.— Section parallel to X Y through L (Fig. 27). on which the pressure acts. This pressure acts constantly upon the face next the gate, that is, upon the annular face; the other face, which corresponds to the total section of the cylinder, is put alter- nately in communication with the accumulator and the return pipe. The piston is attached to the gate by a double nut which can be raised while in use to prevent the former from bending, and its eye is oval shaped to allow for the transverse displacement of the leaves in their various positions. The breech of the cylinder rests on an iron guiding sector. Finally the piston stroke exceeds by 2 centimeters its requisite geometric length, so as to take into account the possible deflections of the leaves. This apparatus is lodged in a pit 3. 50 meters long, 0.85 meter wide, and 0.46 meter deep, just below the coping. It is capable of exer- cising a tensile effort of 6,600 kilograms on the piston rod to open a 584 UNIVERSAL EXPOSITION OF 1889 AT PARIS. leaf, and a compressive effort of 4,710 kilograms to close it. Tlie dimensions are as follows: Meters. Diameter of the piston 0. 155 Diameter of the piston rod 0. 100 Maximum stroke 2.520 Water expended in a double stroke, 47.5 liters. Each apparatus has on its supply pipe a cock to cut off the water; at the bottom of the cylinder a waste air cock; also two cocks for emptying the cylinder in case of need. (50) The apparatus for the small lock consists also of four pieces similar in every respect to those of the large one. Meters. Diameter of the piston 0. 128 Diameter of the piston rod 0. 080 Maximum stroke 2. 060 Water expended in a double stroke, 26.5 liters. This apparatus is capable of exerting on the piston rod a tensile effort of 4,710 kilograms to open the gates, and a compressive effort of 3,016 to close them. (51) The apparatus for operating the culvert sluices for filling and emptying the loch chamber are eight in number, consisting of cylinders with differential pistons having a stroke of 0.55 meter and acting directly on the gridiron sluices, capable of exerting a tensile effort of 8,244 kilograms for raising the sluices, and a compressive effort of 3,816 to close them. CIVIL ENGINEERING, ETC. Hydraulic capstan for new lock at bovgival. 585 5S6 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Hydraulic capstan for new lock at Bocgival. Ftc. 32.— Plan (cover removed) CIVIL ENGINEERING, ETC. 587 (52) The ten hydraulic capstans (Armstrong type modified by M. Barret) placed on the side walls of the great lock can exert a tractive effort of 12,000 kilograms on a cable, at a velocity of 0.43 meter per second (about 7 horse power). All these pieces of apparatus are so arranged that they can be dis- connected (in case of failure of the water supply, or for any other reason! and worked independently by hand (Figs. 19, 20). Fig. 33.— Lateral elevation along I J (Fig. 31). Since these hydraulic appliances were set up in 1883, there have been only three insignificant interruptions in their regular working, and no hindrance has occurred in the navigation; and in virtue of the precautions taken to guard the pipes and presses, there has never been any interruption in the service on account of frost. Fig. 34.— Cross section through the valve chest. (53) Advantages of the system . — The lock chamber of the great lock at Bougival can contain sixteen or seventeen barges with their tow- boat, and the time of lockage is thus made up: Entrance, arrange- ments, and securing the boats, 20 to 25 minutes; closing the gates, 30 seconds; filling the lock chamber (13,800 cubic meters), 15 minutes; opening the gates, 30 seconds; unfastening and hauling out the boats, 15 minutes. We see that for the largest train which the lock can contain, and which may carry 4,500 tons, the total duration of the process, from the time of entrance of the towboat to the exit of the last boat, is 50 minutes, and that of this time 40 minutes are taken up in the en- trance and exit arrangements. 588 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The small lock can pass eight boats per hour. The traffic in 1888 through the Bougival lock exceeded 3,000,000 tons, and the appliances would serve for twice that amount. (54) Cost . — The total cost is as follows: Francs. Cost of land damages 164, 942. 41 Earthwork and masonry for the cut-offs and locks 3,240,000.00 Four pairs of gates 72, 318. 64 Stockades above and below the locks 20, 000. 00 Hydraulic appliances 277, 087. 50 Total 3,774,330.55 The annual cost of working the hydraulic appliances is about 7,200 francs. (55) Conclusions . — From a thorough examination of the working of these hydraulic appliances we may conclude : First. That the introduction of hydraulic appliances in the great lock at Bougival constitutes, in respect to operating by hand or by horse power, a considerable improvement, without which this lock would be very inconvenient, and limited to a traffic of about 3,000,000 tons per annum, while this figure was exceeded in 1888. Second. That the cost of establishment and maintenance is com- pensated by an economy nearly equal in amount made by the boat- men, so that in a general point of view these appliances are advan- tageous, since they allow without increase of cost the working of the locks with a traffic of 5,000,000 or 6,000,000 tons, while the ordi- nary appliances would not suffice for the transit of such a tonnage. These works were directed by M. Boul6, chief engineer, and De Preaudeau, assistant engineer. The hydraulic appliances were con- structed by the Fives-Lille Co. Figs. 12-33, inclusive, are taken by permission from the Porte- feuille des Ponts et Chauss^es. Chapter V. — New movable dam at Poses on the Seine. (56) The movable dam at Poses on the Seine, 202 kilometers below Paris, is the most important of those recently constructed between Paris and Rouen to realize at all times a minimum draught of 3.20 meters. In virtue of its exceptional height, it maintains this draught in a bay extending from Poses to Notre Dame-de-la-Garenne, a dis- tance of 41 kilometers, while the average length of the other bays is only 23 kilometers in the canalized portions of the river between Paris and Rouen. In the preliminary project for the works requisite to give a min- imum draught of 3.20 meters to the lower Seine, it was proposed to erect at Poses a Poir^e dam having a height of 4 meters above the sill ; but even this would be insufficient to cover the shoals of la Mare and Tosny, without requiring excessive dredging, and a second CIVIL ENGINEERING, ETC. Movable dam at Poses on the Seine. Uprights and curtains for the weirs. 589 - 1 j° 5 ' .! . ' i • *u u Fig. 35.— Longitudinal section in front of the uprights, along the line A B, Fig. 36. 590 UNIVERSAL EXPOSITION OF 1889 AT PARIS, Fig. 36.- Fig. 39.— Chain stop Uprights and cu rtains for the weirs. Movable dam at Poses on the Seine. Fig. 38. Fig. 37. Curtain windlass. Elevation. Section. CIVIL ENGINEERING, ETC. 591 dam with a fall of 1 meter was provided for, near Andd, 10 kilome- ters above Poses. The new dam invented by M. Camera raises the upper bay at Poses to 5 meters above the sill, and thus dispenses with the proposed work at And£. Plate IV shows an admirable model of part of the Poses dam, which was exhibited in the Pavilion of Public Works. Before entering into details it will be well to indicate in a general manner the principles and mode of working this new type of dam. Camere's curtains. Flos. 40,41. — Details of the curtain hinges and shoe, cross section and elevation. Figs. 35-40 show the construction of Camera's curtains and their method of suspension. The curtains themselves consist of wooden battens, hinged together (Figs. 40, 41) and resting against vertical supports; these supports are suspended from a bridge, shown in Figs. 42-48. Figs. 37 and 38 show the construction of the windlass for handling the curtains. 592 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (57) The jointed curtain consists of a series of wooden bars (Figs. 35 and 36) arranged horizontally, one above another, resting against the vertical supports of the dam ; the bars have a constant height, but their thickness varies with the head of water they have to sus- tain ; they are joined together by two rows of hinges on their up- stream side. (Figs. 40 and 41). A specially constructed piece is hinged to the lowest bar ; this piece rests upon the flooring of the dam when the curtain is unrolled, and forms the center piece when the curtain is rolled up. It is called the rolling shoe ; it is cylindri- cal in form, having for its base half the spire of an Archimedian spiral ; the upper surface of the shoe is plain, and surmounted by three flanges whose contour forms the second half of the spire of the same spiral. The curtain is suspended by hooks fastened above the water to the fixed portions of the dam, by two chains attached to a ring bolted to the upper bar in line with the two rows of hinges ; it is moved by an endless chain worked by a special windlass. This chain descends on the downstream face of the curtain, passes under the shoe and ascends along the upstream face. The two ends prolonged abovethe curtain are carried by fixed guide pulleys to the curtain windlass. The windlass is so arranged that for rolling up the curtain the two chains move together. The upstream chain rises, while the down- stream chain falls, but with different velocities; the upstream chain moving faster than the other, so that the chain slides under the shoe ; the resulting friction added to the traction of the chain itself causes the shoe to turn about its axis, and, successively, all the bars about their hinges, thus rolling up the curtain from below. It is rolled up wholly, or in part, so as to open wholly or in part the aper- ture which it closed. To unroll the curtain, the upstream chain is let go, and the downstream chain made fast. When the lengths of the suspending chains are properly regulated so as to make the upper bar horizontal, the curtain rolls and unrolls between two vertical planes ; but to avoid any error arising from de- fective construction or regulation, it is found best to have the cur- tain guided, so as to prevent lateral deviation. In the first applica- tion of this system to the Villier dam, the ends of the bars resting on the upstream face of the frames were guided by a small flange on that face. At Poses, two rows of little angle irons are fixed to the downstream bars ; one side of the angle iron, projecting from the bar, strikes against the side of the upright supports in case of the lateral displacement of the curtain. To avoid obstruction in rolling, these angle irons are only placed on the outer spiral so that the cur- tain is only guided for half its height, but that is sufficient owing to its transverse stiffness. Since the guidance of the curtains is assured without making use of the ends of the bars, the curtain may be prolonged beyond the up- Paris Exposition of 1889 — Vol. 3. Civil Engineering, etc. — PLATE IV MODEL, BY REYNARD BROTHERS OF PARIS, OF A PORTION OF THE DAM AT POSES. distinguish them from those which only close one span. It may be observed, that in consequence of the bars projecting over the sup- ports, they resist as if they were built in from these points, and con- sequently need not be stronger than the bars of the simple curtain. H. Ex. 410— vol in 38 CIVIL ENGINEERING, ETC. 593 rights of the successive frames so as to project over half the opening between the succeeding frames, its width thus corresponding to that of two successive spans, so that it can in no case be carried obliquely between the uprights. These latter curtains are called double, to Movable dam at Poses on the Seine Upper bridges of the non navioable passes. 504 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (58) Suspending bridge. — Figs. 42-48 show the sectional plan, two elevations, and details of the suspending and hoisting bridge. The aperture, shown in the plan, is for hauling the curtains through, endwise, when they are to be taken off and stored or repaired. 04 (09) 'Hip hoisting chains. — There are two hoisting chains for each frame; each chain divides into two branches, so that the end of one branch is attached to each upright, thus dividing the strain of lifting the frame into four equal portions (Fig. 35). On the downstream side of the uprights a strong wrought-iron hook with angle irons is attached, for the purpose of raising the frame in case of accident to the chains or to their attachments (Fig. 30). This can be done by lowering, along the upright, a chain, the bight of which will be held securely by the hook. Ringbolts are attached to the upstream side of the uprights, so that the frames may be slung below the upper bridge when any repairs are required. (70) Method of suspending the frames. — The method adopted for suspending the frames has been somewhat simplified in the Port- Mort Dam, and we shall here give the method employed in the more recent dam. This method of suspension is shown in Figs. 54 and 55. The suspending rods are terminated by cross-heads fitted onto the rods by gibs and cotters ; these wrought-iron rods have a cross- shaped section and pass between the braces of the downstream road- way, above which they are united two by two by a cross piece having the section of a double T ) whose extremities can slide vertically between the uprights of two cast-iron chairs bolted to the roadway. In their normal position these extremities rest on chairs by means of regulating iron wedges. Similar wedges, placed between the up- per face of the crosspiece and the upper bearings of the chairs pre- vent the frames from lifting. (71) Foot bridge. — The foot bridge, made up of framed sections 1.16 meters longer, is constructed of U iron, to which the iron floor- ing is riveted ; upon this flooring the rails for carrying the windlass are laid. The upstream side of the section is hinged to the down- stream side of the uprights. The transverse bars of the section are prolonged, and strike against corbels riveted on the webs of the uprights, so as to keep the sections of the foot bridge horizontal when it is lowered. (Figs. 36 and 42.) (72) Method of attaching the curtains.— The suspending chains are hooked to rings attached to the two outside uprights of each frame at 1.25 meters above the foot bridge. The two pulleys for rolling the curtains are placed between the intermediate uprights. The lower pulley, holding the downstream chains, is slightly smaller than the other. This inequality insures a distance between the chains equal to the thickness of the first curtain bar. Besides rolling the curtain, each side of the endless chain can be fixed upon its guide pulley by a stop (Fig. 39), carrying a finger, which enters the link of a chain when the lever is lowered. Finally, the uprights have on their upstream faces iron claws, which serve as stops to the rolled curtain. (73) Details of the curtains. — Dimensions. — Each curtain corre- CIVIL ENGINEERING, ETC. 005 sponds to an opening 2.32 meters wide and 5.35 meters high in the deep passes. Tlie bars of yellow pine are all 0.078 meter high, with a play of 0.002 meter between the bars to allow for swelling ; their length is 2.28 meters, giving a play of 0.04 meter between two neigh- boring curtains ; this interval is sufficient, and can be closed by a joint cover if the dam reqires to be made tight. The thickness of the upper bar is 0.04 meter, and it increases pro- gressively downward to 0.09 meter for the deep passes. It is calcu- lated to resist a pressure of 60 kilograms per square centimeter. The upper bar, exposed to shocks from floating bodies, is strength- ened by an angle iron. The hollow cast-iron rolling shoes are heavy enough to cause the curtain to sink easily into the water when unrolled. The rows of hinges form a kind of chain resisting all efforts ex- erted on the chain in the act of rolling. These hinges are of bronze, so as not to rust; they have strong flanges, and their axles are of drawn phosphorus bronze. All the handling machinery can be car- ried on cars rolling on the service-bridge tracks. (74) Windlass for handling the frames. — The maximum effort which can be produced by this apparatus is at the termination of the lifting, and amounts to 4,900 kilograms for the deepest passes. This effort, transmitted by the chains to the windlass, is exerted by four men at the cranks, or by a small double-cylinder steam engine mounted on the windlass. A brake serves to regulate the velocity of the descent when the frames are lowered. (75) To raise the frames , — With the suspension above described and in use at Port-Mort the operation is as follows: Lifting jacks, shown in Fig. 54, are placed under the crosspieces uniting the two suspending rods of a frame above the downstream roadway. Each jack rests upon a platform arranged for this purpose in the horizon- tal bracing of the roadway. After placing the jack and removing the wedges which prevent the lifting, the jack is screwed up, care being taken to wedge the ends of the crosspiece as it moves up; this wedging serves to sustain the lifted frames. The chains from the windlass on the upper bridge are then hooked on, and the frames are rotated to a horizontal position and made fast to the under side of the upper bridge. (76) Execution of the work . — The foundations were laid on a bank of chalk, from 5 to 5.50 meters below the sea level. Two systems were employed ; first a cofferdam pumped out above a layer of beton filled in an inclosure of artificial blocks (for the abutment on the right bank, for piers Nos, 1, 2, ?, and for the floorings of the passes, Nos. 1, 2, 3, and 4.). Second. Foundations in caissons by compressed air for piers Nos. 4, 5, 6, the abutment on the left bank, and the floorings for passes 5, 6, 7. UNIVERSAL EXPOSITION OK 1889 AT PARIS. 606 The surface covered by the foundations of the Poses Dam and its approaches amounts to 4,905.58 square meters; 04,037 cubic meters of masonry were laid. (77) Weight of the iron work . — Weight of the iron in the bridges and frames, 1,316,991 kilograms; weight of a curtain with its chains for the deepest passes, 911 kilograms; weirs, 510 kilograms. The final project was approved October 2G, 1878. Work on the foundation began the 24th of May, 1880, the dam was completed on the 24th of September, 1885, and lias given entire satisfaction since. (78) Cost . — Cost per running meter : Francs. Masonry foundations 13, 345 Iron work: U pper bridges 1 , 87 1 Frames 878 Curtains, etc 421 Total 16,515 The project of the Poses Dam was drawn up by M. Camerd, and executed principally under his direction. The figures 35-50 are taken by permission from the Portfeuille des Ponts et Chaussdes. Chapter VI. — Villez movable dam on the Seine. (79) The Villez Dam is situated on the Seine 145 kilometers from Paris. Figure 50 shows the general arrangement of the dam, which consists of two navigable passes and a weir having a linear opening of 201.25 meters, together with two locks. The total length of the dam is 223.15 meters. (80) System of dosing . — The dam is closed by a system of frames and curtains (Fig. 57). Each curtain is suspended by its upper bars from a frame over two adjacent Poirde frames (fermettes). This suspending frame is completely independent of the fermettes, being only attached to them by pins (Fig. 58). The regulation of the height of the water is done by raising or lowering the curtains, the flow taking place underneath; the regu- lation, at times of low water, maybe made without moving the cur- tains, by flash boards 0.30 meter high arranged above the curtains. (81) Opening the dam . — The process of completely opening the dam is as follows: The curtain frames with their curtains are transported over the service bridge to their storehouse on the bank ; the flooring of this bridge and the rails uniting the dam frames are taken up ; and, finally, these frames are lowered one after another, beginning with the one in each pass farthest from the bank. The time taken for these operations, counting from the carrying away CIVIL ENGINEERING, ETC. GOT of the first curtain, is about 22 hours, corresponding to the complete opening of one linear meter in 11| minutes. When the freshet sub- sides and the water tends to fall be- low the normal level, the inverse operations are made and the dam is closed. (82) Description of the dam . — The flooring consists of a raised portion, forming the upstream sill, united by a curved portion with a recess which holds the lowered frames; the sill is 4 meters below the upper bay; the recess protects the frames from the keels of the passing boats. The great pressure supported by the frames requires their bearings on the flooring to be strong and secure; they are for this reason at- tached to iron double T bars as long as the width of the recess, and united transversely by two other double T bars. This grating is anchored, as well as built into the flooring. In constructing the floor- ing for the deep passes arrange- ments are provided for setting up a cofferdam for repairs. These ar- rangements consist of recesses made in the piers to hold joists, so as to separate adjacent passes; also iron boxes and rings anchored in the masonry above and below in the flooring. To aid in pumping out these temporary cofferdams, a well is sunk in each floor. These sup- plementary constructions were of great service in improving the sill of the dam after its completion. (88) The frames . — The frames are planned so as to present the minimum of obstruction consistent with strength. The upstream up- rights of the frames have a small T iron on their face, the pro- jecting web of which serves as a guide to the curtain bars resting on this upright. The bracing of the frames is calculated on the sup- position that the pressure of the water is distributed over the whole 60S UNIVERSAL EXPOSITION OF 1889 AT PARIS. height of the uprights, instead of being transmitted only at the top, as in the case of needles. A bracket placed on the downstream upright serves to widen the service bridge roadway and allows two tracks to be laid, the rails serving as braces between the frames, and replacing the catches used in the older frames. The great frames are moved by means of flatiron bars, each in three parts, jointed together, and having a joint at each extremity. Fig. 57. Lowering the frames at Villez Dam. (84) Lowering fhe frames . — When a frame is to be lowered the joint of one extremity of a bar is pinned to the upper cross bar of the frame and the other extremity made fast to a car movable on the track on the service bridge; this car is held by a chain passed around the drum of a windlass, the latter being held by another chain made fast to the next pier or abutment (Fig. 57). To lower the frame, it is only necessary to push the car forward and pay out the windlass chain. When the frame is lowered the flat bar fixed to the car is CIVIL ENGINEERING, ETC. 609 detached and pinned to the side of the cross bar of the following frame still standing; the operation is repeated, and while the second frame is lowered the Hat jointed bar connecting the two frames folds together forming a V- the unequal branches coming together between the two frames, without forming heaps like the chains. The frames are lifted by reversing the operation. (85) Thetypeof curtain adopted for this dam (described pp. 501-593) is that of M. Camerd. The dimensions of the curtain bars for the deepest passes are 1.09 meters long, 0.058 meter high, and the thick- ness from 0.04 to 0.08 meter. The frame supporting the curtain, which also holds it when rolled up, is an iron frame (Figs. 58 and 59), DAM AT POSES. Fig. 58.— Windlass for hoisting and Fig. 59.— Mode of unshipping and trans- lowering the curtains. porting a curtain. whose upper bar holds the hooks for the suspending chains, and whose uprights are terminated by forks fitting on the horizontal pins with heads forming part of the dam frame. By means of these pins the curtain frame may be set up directly over the uprights of two successive dam frames and kept in this position by screws, or disengaged and turned about these pins and deposited upon the curtain car (Fig. 59). The curtain frame has in the middle two guide pulleys which carry the curtain chain, and a box to hold the slack of this chain. (86) The curtain is rolled or unrolled by an endless chain as fol- lows: Each line of the endless chain passing over the guide pulleys forms two bights, one to the right and the other to the left of the curtain frame (Fig. 58); the one passing around the curtain regulates the amount rolled up. To operate the curtain, the two lines of the chain of the downstream bight pass over the chain pulleys of the windlass ; the combined motion of these pulleys produces an elongation or contraction of the other bight. H. Ex. 410 — vol ill 39 ()10 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (87) The windlass for handling is mounted on a car rolling on the rails of the foot bridge to bring it in front of the curtain to be moved. When placed it is clamped to one rail of the track ; on the other side a movable buffer on the upper part of the windlass rests against the curtain frame and resists its tendency to turn in the upstream direction. The windlass carries two outside chain pulleys (Fig. 58), corre- sponding to the curtain-frame guide pulleys ; the lines of chains are put upon these and maintained in their places by rotating stops which can be lifted to allow the chains to be taken off or put on. The pulleys are keyed to shafts driven by the windlass gearing ; the lower pulley may be engaged or disengaged. When engaged it turns in an opposite direction from the upper pulley, and its circum- ferential velocity is a fraction of that of the other. This being so, to roll up the curtain the lower pulley is engaged, and the upper pulley exerts an effort on its chain while the lower pulley pays out its chain ; on account of the difference of the velocities of the two pulleys a shortening of the bight passing round the curtain takes place, and the curtain rolls up. To unroll the curtain, the lower pulley is disengaged, its chain is made fast by a stop on the guide pulley of the curtain frame, the upper pulley turns, letting go the chain, the bight lengthens, and the curtain unrolls. (88) The curtain frame is shipped on a special car carrying an inclined plane furnished with a windlass and chain (Fig. 59). This car is brought in front of the curtain, the screws fastening the cur- tain frame to the dam frame are removed, so as to allow the former to turn around its journals. The windlass chain is hooked to the upper bar of the curtain frame, and the latter turns round its jour- nals until it rests upon the inclined plane; then by the continued action of the windlass it is hoisted upon the car by moving upon rollers fixed to the inclined plane. The curtain frame, thus com- pletely separated from the dam frames, can be carried off on the car. It is replaced by the reverse process. The project for the Yillez dam was prepared under the direction of M. Lagrend, chief engineer, by M. M. Cheysson and Camerd, engi- neers; the latter superintended the work and invented the system of curtains. Chapter VII. — Movable fish way erected at Port-Mort Dam on the Seine. (89) A fish swimming up a river, meeting a dam, and endeavoring to ascend, seeks that point where the water is freshest; this is in the middle of the pass — corresponding to the main channel in movable dams — and not under the shelter of the fixed parts; so that fish ways, if we wish them used, should be placed accordingly. CIVIL ENGINEERING, ETC. 611 Starting from these principles M. Camerd proposed, in 1878, to substitute for the fixed masonry fish ways hitherto constructed near the piers or abutments of movable dams, portable fish ways, each formed of a long trough of wood or sheet iron with cross parti- tions, resting its downstream end upon a floater and its upstream end upon the upper bar of the curtain dam properly lowered. With a construction of this kind, arranged so as to be easily shifted, it is possible to seek in the dam the best position for the way so the fish will go up naturally, and the route which they choose shall not be encumbered by any fixed obstruction. (90) The annexed figure indicates the arrangements adopted at Port-Mort. The dam is a curtain dam, like that at Poses. The wooden trough of the way is formed "in two sections; the principal section rests on the floater, and is hung above on a shaft arranged on the outer faces of the uprights so as to oscillate as the lower bay rises and falls. The second section, which is fixed, is placed between 612 UNIVERSAL EXPOSITION OF 1889 AT PARIS. two uprights. Its extremity opens into the upper bay, and it joins the other section upon which it rests. Its length has been deter- mined by assuming that its inclination should not be more than .020 per meter when the dam is at its full height. The length of the principal section is therefore 10.15 meters; its width beyond the frames is 1.4G meters; the partitions, 0.43 meter high by 0.30 meter wide, are 1.25 meters apart. (01) The principal section rests upon a little iron bridge. The downstream floater is formed by two little covered boats arranged on each side of the way and firmly united. The little section across the dam frame rests above on the upper bar of the curtains properly lowered, and laterally against the up- stream face of the uprights of the dam, secured by angle irons fixed to its exterior sides. Below, it is boxed in by two cheeks arranged at the end of the principal sections, and rests on a cylindrical sur- face, so as to allow oscillations. The portion situated at the entrance of the trough in the upper bay is movable around an axis placed at its base. This allows the regulation of water flowing down the way according to the level of the lower bay. (92) Erection . — The way is set up between two frames. To lower it it is sufficient to lower the upper bars of the two curtains on which it rests by lengthening their suspending chains. We thus obtain sufficient space above. The portion of this space not filled by the way, is closed on each side by two little hand sluices. The chains holding the suspension axle of the way are hooked in the uprights of the dam and the axle is made fast by other chains attached to the frame shaft. The fish way is brought into place with its upper ex- tremity resting on a pontoon, while its lower extremity rests on the floaters. By attaching then the upper end of the way to the top of the service bridge the bearings placed under the beams are put upon the axle, and the floater is held by guys from the neighboring piers. The curved piece connecting the two portions of the troughs is put up across the dam frames. To remove the way the inverse opera- tions are performed. The movable fish way for this dam was planned and executed under the direction of M. Camerd by M. Clerc. Chapter VIII.— Torcy-Neuf Reservoir for feeding the Cen- tral Canal. (93) The great improvements for deepening the Central Canal, re- quired the establishment of a new storage dam near Creusot. The new reservoir received the name of Torcy-Neuf to distinguish it from another called Torcy. Torcy-Neuf is 5 kilometers northwest from the summit level of the Central Canal. CIVIL ENGINEERING, 1 TC. 613 The reservoir has a surface of 166 hectares, a perimeter of 15 kilo- meters, a height of 14.50 meters; it contains 8,767,000 cubic meters, and doubles the amount of water heretofore available at this level. A waste weir 12 meters long is at the left end of the dike. The supply conduits start from a tower which is built in the reservoir at the foot of the dike, and which allows the waste water to flow over the top. (94) The dike, well rooted at both ends in the side of a hill, con- sists of a great filling of sand and clay (64 per cent of sand to 34 of clay) 436.70 meters long, 5.50 meters wide at the top, and 52.90 meters, at the base ; its maximum height is 16.30 meters, and its vol- ume 129,000 cubic meters. The slope toward the water (Fig. 62) is protected by a series of masonry pitcliings 1.50 meters high, inclined 45 degrees, and sepa- rated by berms 0.90 meter wide, two intermediate oues being 2 meters wide. 614 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The exterior slope, without revetment, is planted with acacias fora distance of 5 meters in height. The slope is 2.73 base to 2 of height. The upper platform of the dike is 1.80 meters above the water level; it is of masonry, like the slope toward the water, and sur- mounted by a parapet 1.20 meters, to stop the waves. The foot of the slope rests on a revetment wall 1.50 meters thick, built in a distance of 1 meter into the solid rock (red sandstone) for the whole length of the dike. The maximum height of this wall is 7 meters. The dike, below the revetment and the platform, rests on bare rock. To increase the tightness at the base there were three layers of puddled clay laid down within the reservoir parallel to the axis of the dike and penetrating 1 meter into the rock foundation. The earth of the dike was vigorously rolled in successive layei*s, after adding water and powdered lime according to their degree of dampness; the layers being compressed from 0.10 to 0.075 meter after the operation. Corrugated rollers drawn by horses and weighing 750 kilograms, and also steam rollers weighing 5,000 kilograms were used. A horse-roller compressed 80 cubic meters per day, measured after compression, while a steam roller compressed 500 meters. The cost, including leveling, watering, addition of lime, rolling, etc., was 0.23 franc per cubic meter. That part of the dike under the outside slope was rammed in lay- ers of 0.20 meter thick, reduced to 0.15 meter after rolling; it rests on a natural bed carefully prepared. (95) 7 he (fate tower . — The water, instead of being conveyed in mains or culverts through the dike, is let into a tower built in the reservoir at the foot of the dike. It serves to discharge the waste water and dispenses with the waste weir; this weir has been retained through fear lest the large amount of water flowing through the tower should undermine or dislocate the masonry. These appre- hensions proved groundless. The experiment of passing the waste water through the tower, combined with the gate closing the tail- race, has been perfectly successful. The gate tower is square on the outside and has in the interior a well 1.50 meters in diameter through which the mouthpieces pass. This well opens below into the tail race. The coping of the tower is on the same level as that of the dike, that is, 16.30 meters above the bottom of the lowest mouthpiece. It has a platform 3.50 meters square, on which is placed the appara- tus for moving the gates. The faces of the tower have a batter of one-twentieth. The well terminates in a cylindrical chamber 2 meters in diameter and 2 meters deep, kept constantly full of water to break the destruc- CIVIL ENGINEERING, ETC. 015 tive shock of the water upon the masonry. Founded on red sand- stone, the tower exerts a pressure of 3.58 kilograms per square centi- meter. (96) There are three mouthpieces, situated vertically over each other at a distance of 4.80 meters apart. The orifices are 0.80 by 0.40 meter and are closed by special cylindrical valves. The middle 616 UNIVERSAL EXPOSITION OF 1889 AT PARIS. and upper mouthpieces are simple ducts of rectangular section opened in the walls of the tower; their bottoms are curved so as to intersect the walls at an angle of 45 degrees, so that the stream at the moment of opening shall strike the masonry obliquely. The water is let into the tower by four openings, each 2.20 meters long, made at the top of its four faces; the sills of these openings are 0.40 meter below the standard level. Each of them is surmounted by an oaken gate kept in its place by (J irons fastened against the sides of the openings. These gates are taken off in case of a freshet. The tower is accessible from the dike by an iron foot bridge. The ribbed plate flooring, 21.40 meters long, 1.14 meters wide, is sup- ported on two arches of 18.20 meters chord and 2.50 meters rise. The new system of valve towers has the advantage of economy, combined with greater security and stability for the dike, as well as affording greater facilities for repairs. (97) The passage of the water mains through a mass of masonry in an earthen dike destroys the homogeneity of the latter; on both sides of this mass the earth has to be hand-rammed, and consequently badly done, no matter how much care is taken. The settlement of this earth leaves spaces which may cause filtrations and become sources of real danger. With the tower, the dike is only cut at its base; the hand-ramming is reduced to a minimum ; as soon as the top of the waste culvert is reached, all the ramming is done with rollers, and consequently much better. A notable economy results from dispensing with the heavy masses of masonry through which ordinarily the mains run, from the omission of the waste weir with its tail race, and from rolling by steam and horse power instead of ramming by hand. The sluices are very difficult of access in the long culverts ordi- narily used, and are consequently rarely repaired. With the tower, on the contrary, when the mouth of a main has been stopped by a wooden plug, placed within the tower in a chamber arranged for this purpose, a diver can easily take down the valves and valve rods, and replace them after they have been repaired in the shop. The long culvert under the dike can be easily inspected and re- paired. The guard sluice being raised, one is not entirely cut off from the upper end ; light and air come in from the tower. (98) Sluices . — Rectangular sluices have the great inconvenience of moving with very considerable friction for great heads of water ; use has to be made of powerful and costly jacks, whose friction in- creases the effort to be made ; they have to be fastened by heavy irons to solid pieces of masonry, that they may not give way. At Torcy-Neuf the endeavor has been to diminish the friction as much as possible and consequently to employ simpler moving appa- ratus. CIVIL ENGINEERING, ETC. 617 The sluice (Figs. G3 and 04) is not plane but cylindrical, and firmly attached to a rigid horizontal concentric shaft ; it has no opening. It turns at a short distance from its seat, which is cylindrical and concentric, without resting upon it. It includes a movable frame which it carries with it in its motion, but the latter is not attached to the shaft. The pressure of the water on this frame is exerted only at its edges ; it rests and rubs only against the valve seat. The joint Fios. 63, 64, 65.— Torcy Neuf reservoir. Section, elevation, and details of the sluice. between the frame and sluice is packed with a rubber ring, which does not sensibly interfere with the independence of the frame; this ring is inclosed in a slot and protected from shocks. Comparing this with the ordinary flat sluice, the theoretical friction is reduced 92 per cent. This system, which gives entire satisfaction, is due to M. Eugene Resal. The three sluices are moved by jacks placed on a single post in the middle of the platform of the tower ; 618 UNIVERSAL EXPOSITION OF 1889 AT PARIS. the motion is transmitted to the rods by endless chains and horizon- tal axles. (90) Guard sluice. — The guard sluice, at the bottom of the tower, to close the waste culvert is upon the same principle. It was devised by M. Hirsch, chief engineer. It is principally of iron, 1.80 meters high and 1.10 meters wide ; it consists of a strong plate iron wagon- ette with two pairs of wheels, rolling on vertical rails set into the walls of the masonry well (Figs. 06, 07, 68, and 09). The wagonette rises without resting against a cast-iron frame fixed in front of the Fig. 68. Fig. 69. Figs. 66, 67, 68, 69.— Torey Neuf reservoir. Elevation, vertical section, and horizontal section of the guard gate, with details. culvert. The contact takes place along a slightly inclined plane by a border formed of jointed bronze rules independent of the sluice, but carried along with it in its motion. Like the other sluice, it is packed by rubber between the jointed rules and the wagonette ; the faces of contact of the rules and the rubber are galvanized. The jack moving the suspending rod is placed on the platform of the tower. CIVIL ENGINEERING, ETC. 619 The head of water on the center of t lie guard sluice is 13.60 meters while the pressure on a simple plain sluice having a surface of 2 square meters would be about 27,000 kilograms; the rules are only pressed against the seat with a force of 3,000 kilograms. Admitting a coefficient of 40 per cent for friction, the weight of the sluice being 1,000 kilograms, the effort to raise the sluice does not exceed 2,200 kilograms, which is easily managed by a jack with a -theoretical power of 750. This sluice was set up in 1S88 and works perfectly. It affords the means, as it is raised more or less, of keeping the water in the tower at such a given constant height as may be found most advantageous. We may thus diminish at will the height of fall of the water into the tower. (100) Cost . — The total cost of the work was 2,233,183.84 francs. The cost of the dike, tower, and waste weir together was 585,896.53 francs. The rest was spent for land, buildings, and the removal and reestablishment of the roads and railroad passing through the loca- tion. The project was prepared by MM. Desmur, engineer, and Fontaine, chief engineer. Chapter IX. — New high lift locks on the Central Canal. (101) The French Government has just completed a number of high lift locks on the central canal to replace old ones of 2.60 meters lift. The new locks have a lift of 5.20 meters with chamber wall 8.20 meters high. The flooring is 0.25 meter below the head miter sill and 2.85 meters below the normal level. The cylindrical supply sluice (Fig. 75) is placed at the bottom of each upstream quoin un- der a full centered arch of 2.30 meters span and 2.55 meters height. Two small recesses serve to support a little joist dam allowing the sluice chamber to be emptied and the sluice inspected and repaired without stopping the traffic. A grating is ordinarily placed in these recesses to stop floating bodies. (102) The lift wall is 5.20 meters high and 1.60 meters thick with the downstream face curved. The cylindrical sluice pits, 1.40 me- ters in diameter, are sunk in each chamber wall to a depth of 4.95 meters. From the bottom of these pits on a level with the tail miter sill, the full centered culvert begins, for filling and emptying the chamber. It extends lengthwise through the entire chamber and discharges into it by four rectangular openings equally distributed, from 0.60 to 0.80 meter wide by 0.80 to 1 meter high. The largest admits the passage of a man for inspection or repairs. The chord of the invert is 2.60 meters below the normal level, 2 meters, of the tail bay. (Fig. 70.) 620 UNIVERSAL EXPOSITION OE 1889 AT PARIS. Under the flooring, two files of drains begin 10 meters from the lift wall, emptying into the riprap of the tail bay. All upward pres- sure is thus avoided besides facilitating the foundation constructions. Each chamber wall is3.G0 meters thick at the base, and 1.20 me- ters at the top; it is 8.20 meters high. Two life ladders formed of iron bars are placed in little recesses in the walls. CIVIL ENGINEERING, ETC. 621 To resist the thrust oil the tail gates, the tail walls are 4.34 meters at the top and G meters at the base, terminated by wing walls hav- ing a batter of one-twentieth (Fig. 74). Two recesses allow a cofferdam to be set up to separate the lock chamber from the tail bay. A short distance upstream from the tail quoins, the lateral culvert in each chamber wall rises and empties into a large pit 2.30 meters square and 6.25 meters high, in which the cylindrical emptying valve is placed (Fig. 76). This pit, and the lock chamber form two reser- voirs communicating by four rectangular orifices equally for filling and emptying. The water reaches the pit and escapes at the bottom under the boats without producing any current in the chamber. The valve seat is 0.65 meter below the level of the tail bay, so as not to make a siphon of the discharging culvert, and also to allow the in- spection of the sluice by a slight lowering of the tail bay. Figs. 75 and 76. — Half cross sections through the axes of the upstream and downstream pits. This sluice opens a pit 1.40 meters in diameter and 1.95 meters high, at the bottom of which, at the level of the tail miter sill, the emptying culvert begins. This latter having a great section, 1 me- ter wide and from 1.60 to 2 meters high, makes a circuit of the hol- low quoin so as to empty into the tail bay at right angles to the axis of the lock, thffs avoiding the introduction of the water with great velocity into the tail bay, and consequent erosion. One of these high lift locks has a bridge erected on the tail walls; the roadway being 1.30 meters below the coping, it is 6.80 meters span and covers, be- side the boat passages, two staircases each 0.80 meter wide. (103) Description of the cylindrical sluices (Fig. 77). — The lock has four cylindrical cast-iron sluices of equal size, two for filling, and two for emptying. Each sluice consists of fixed and movable parts. The fixed parts consist of a seat 1.40 meters in diameter, built in and fastened to the masonry, and carrying three uprights in the form of flanges united "by an upper crown; a hollow cylinder fixed upon the crown receiv- G22 UNIVERSAL EXPOSITION OF 1889 AT PARIS. ing the sluice when it is raised; a cover bolted to this cylinder and surmounted by a pipe for the passage of the lilting rod and the escape of air. The seat is placed horizontal and maintained so by means of three regulating screws embedded afterwards in cement. The movable part is a cast-iron crown 0.4G7 meter in height, and 1.42 meters in interior diameter raised by a jack. It slides on a fixed part and opens or closes the space between the seat and the upper cylinder. The vertical pressure of the water is supported by the cover. The movable portion only is exposed to lateral pressures which are in equilibrium. The only weight to be raised is the Fig. 77.— Cross section of Fontaine's cylindrical sluice; the sluice closed. weight of the sluice, which is about 370 kilograms. The distance raised is 0.385 meter; the time of raising twelve or thirteen seconds and the effort only 7 kilograms. The downstream sluices work un- der a head of 5.20 meters as easily as the upstream ones under the head of 2. GO meters. The closed sluice rests on a little rubber ring, fastened into a slot in the seat. The upper joint is made tight by a leather band, kept in place by the pressure of the water. This sluice, which has been in use for the last six years, has worked perfectly. It has the follow- ing advantages : CIVIL ENGINEERING, ETC. 623 First. There are no resistances except the weight and friction of the water on the iron, without any pressure of the water. raising the sluice a height /i= . Figs. 78 and 79.— Lock on the Central Canal. Upstream elevation and section of the lower gates of the canal lock. 624 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Third. The head is greater than upon an equal orifice made in a vertical plane. This sluice has been adopted elsewhere for Paris and for sea locks. It solves the problem of liigh-lift locks with saving basins. For great reservoirs, a single cylindrical sluice of small diameter will advantageously replace the usual, complicated and expensive systems. The use of cylindrical sluices enables all others to be dispensed with, which is an advantage with respect to tightness and repairs. The hand rails, for this reason, can be placed on the upstream side of the foot bridge, and thus sheltered from the shocks of passing boats when the leaf is opened. (104) Gates . — The head gates consist of two leaves of galvanized plate iron. The tail gates are 9.25 meters high, including the hand rail ; they consist of two leaves of galvanized plate iron and steel. Each has a frame strengthened by eight horizontal beams so spaced as to support about the same load, and by ten uprights united by the first set. These pieces consist of a web and four angle irons of mild steel. By the use of this metal the weight of the frame is reduced, making an economy of construction, and facilitating the setting up and the working. The heel and miter posts, as well as the uprights, are strengthened by three wide iron bands on their downstream faces, to give them more stiffness. The skin is formed by eighteen iron plates 0.007 me- ter thick, built in at the edges, curved so as to have a flexure of 0.070 meter, and riveted to the upstream face of the steel frame. They show no change of form under pressure. The pressure of the leaf against the heel post at the bottom is spread over seven iron disks upon friction plates; these last, fur- nished with three adjusting screws, are arranged so that all bear and work. The collar, fixed to the anchor straps by two strong screws and nuts, has a joint besides. It can move horizontally in all directions and give the axis of rotation an exact vertical position. Each leaf is furnished with a gridiron valve formed of two hollow cast-iron cylinders united by flanges, to be used in the case — which may never happen — when the water is so low as to uncover the sills of the cylindrical sluices. All the gates are moved easily, even by children, by means of little simple and convenient windlasses. (105) Time of lockage . — The lock, containing 1,200 cubic meters, is filled in 3 minutes 10 seconds and emptied in 3 minutes 15 seconds; the time for lockage, 14 minutes, being thus distributed: Min. Sec. Entrance of the boat 4 10 Closing the gates 0 40 Filling the chamber 3 10 Opening the gates 0 40 Exit of the boat 5 20 CIVIL ENGINEERING, ETC. 625 (106) Cost . — The cost of the lock was 120,000 francs, made up as follows: Francs. Earthwork 8,000 Masonry work 96, 000 Lock gates 11, 100 Cylindrical sluices 3, 400 Gratings and windlasses 1 , 500 Total 120, 000 The new lock appears to be very satisfactory, and promises to be- come the type to be adopted in future. The rapidity of lockage without injury to the boats from the motion of the water, and the ease of operating all the appliances, are thoroughly appreciated. The group of locks, of which this was one, was designed and exe- cuted under the direction of M. Fontaine, chief engineer, by Messrs. Resal, Moraillon, and Variot, assistant engineers. Chapter X. — Cable towage for boats on canals and rivers. (107) The principal difficulties in cable towage arise from the fol- lowing circumstances: First. That owing to the obliquity of the towrope, the irregularity of its motion, and the displacement of the joint between the rope and the cable, the cable can not have a steady motion. Second. Whenever the towrope passes over the groove of a guide pulley it is caught there. It must pass the pulley without dragging the cable, which is a difficult matter, especially in going around concave curves. Third. The joint between the towrope and the cable should be such that the former can not be twisted upon the latter by the torsion of the cable, otherwise the towrope will be wound upon it, besides being very difficult to detach from it. Fourth. The towrope must be easily detached from the cable at any instant — an operation of some difficulty, as it is done by a cord 60, 80, or 150 meters long, which forms knots by being dragged on the ground or through the water. Fifth. Uncoupling should be progressive, although we couple suddenly to a cable in motion. (108) System adopted . — The system of cable towage introduced by M. Maurice Levy solves all these difficulties as follows: — The first condition of success was, according to the author, to avoid all irregular motions of the cable. For this purpose, instead of de- termining the weight and tension of the cable according to the usual rules governing telodynamic transmission, he determines them by the double condition of maintaining the oscillations of the cable, H. Ex. 410 — vol ill 40 UNIVERSAL EXPOSITION OF 1889 AT PARIS. 626 whether horizontal o v vertical, within certain prescribed limits, which can he made as small as may be desired. This requires that the cable should be heavy (about 3 kilograms per meter), and that it should be set up with an initial tension incomparably greater than that usually adopted in telodynamic cables. This tension, as well as the weight of the cable, depends on the length of circuit and the speed required for the boats. This figure is taken by permission from La Nature. 627 CIVIL ENGINEERING, ETC. The vertical supporting pulleys are 0.80 meter in diameter, and have a depth of groove of 0.20 meter. A roller on the top of the pulley prevents the cable from leaving it, but the towrope attachment would catch between the pulley and the guide roller. To obviate this openings are made on the water side of the pulley grooves, con- sisting of notches extending the whole width of the groove and hav- ing their edges curved in the form of the involute of a circle (Fig. 80 ). The towrope joint, or coupling, remains in the groove until it is caught by the first notch, which it follows; then, on account of the obliquity of the towrope, it descends along one edge, is carried up on the other, and passes off. (109) The passage around convex bends in the banks presents no difficulty; it is accomplished with the aid of a horizontal pulley, or rather one slightly inclined in the direction of the two sides of the endless cable. Two types of pulleys are adopted: one 1.40 meters and the other 2 meters in diameter at the bottom of the grooves, with 0. 10 meter depth of groove. The first, for curves from 200 to 300 meters radius, and the second for those of smaller radii. These pulleys have no need of notches, as the cable, with its towrope coup- ling, only passes on the water side and thus escapes. On account of the great tension of the cable there is no danger that the towrope will pull it off. (110) The passage around concave angles is, on the contrary, an extremely delicate problem. In that case, the cable passing round the pulley on the land side, the towrope joint can not clear itself unless we adopt very special and precise arrangements. The following method was adopted (Figs. 81 and 82): In the elevation, the plane of the lower pulley is supposed to be re- volved to coincide with that of the upper one. Two vei’tical pulleys are taken, having a common tangent, to the bottom of their respective grooves, one of the pulleys being in the plane of the part coming on, and the other in that of the part going off. The cable rolls upon the first (which we may suppose to be the upper one) and descends vertically along the common tangent, and then passes on to the second. This solution permits any change of direction whatever by the aid of two vertical pulleys, and consequently it suffices to notch these pulleys like the supporting pulleys to let the towrope coupling es- cape. But it subjects the cable to two consecutive bends at right angles. In order to save the cable from wear, large 2-meter pulleys are used, and on account of tlieir great dimensions the number of the notches is increased. The expense of such pulleys with tlieir supports would be con- siderable if they had to be used wherever there is a concave angle, 628 UNIVERSAL EXPOSITION OF 1889 AT PARIS. and this arrangement is only suitable for curves with exceptionally short radii, or at the entrance of tunnels, Avhere it maybe convenient to suddenly change the direction. For the usual deviations a large pulley is used of the type of 1.40 or 2 meters, furnished with notches on the upper face (Fig. 83). This solution is derived from that of the two vertical pulleys. Figs. 81 and 82.— Cable towage. Elevation and plan of a double pulley for a concave angle. The cable comes on to the upper pulley and passes to the lower. The principle of the two pulleys is very elastic. We may, for instance, take both pulleys inclined, or one vertical and the other inclined. Then we may arrange so that the first shall he an ordinary pulley 0.60 meter, and there remains only one large pulley. But the inclination of the latter, its direction relatively to that of the cable CIVIL ENGINEERING, ETC. 629 as it comes on and goes off, and the length and width of the notches, should he determined with the most perfect precision by certain rules which have been established by theory and experiment. (Ill) Method of attaching the boats to the cable. — The towrope can not be made fast directly to the cable, because the latter being sub- jected to constant twisting motions would cause the former to twist around it, thereby losing considerable of its length, and rendering its detachment impossible during the journey. This detachment should be capable of being instantly done in case of an accident, or when the boat is to be stopped. For this reason cable-road grips are inap- plicable ; hence pairs of rings are placed at intervals on the cable (Fig. 80 ). One ring serves as a fixed axis of rotation to the other ring which is movable about fig. as. -single puUey for concave the cable. The latter ring has two bear- angles, ings around which the U -shaped shackle turns. This shackle may therefore have two rotations, one around the cable and the other around an axis perpendicular to it. Figs. 84 and 85.— Elevation and section of the hooking on and casting off grip. The grip attached to the towrope consists of a hollow cylinder c c c c, in which the piston G G G moves; the piston rod p q passing through the bottom of the cylinder; one end of a spiral spring sur- rounding the rod p q rests against the bottom of the cylinder G G, and the other against the piston. 630 UNIVERSAL EXPOSITION OF 1889 AT PARIS. A frame P Q is placed in a diametral plane of the cylinder and attached to it; it carries a finger, D, movable around an axle; the end of the finger fits into a cylindrical cavity in the piston G G. If D is put in the cavity it is caught there. If the rod p is pulled the piston follows it, compressing the spring; the finger D then becomes free to turn on its axis. The end of the towrope on the boat is permanently attached by a ring to P. One extremity of the grip cord is on the boat and the other permanently attached to p (Fig. 86). The cord is for releasing the finger around which the bight of a leash is placed; this leash passes through the ring on the cable, and is permanently fastened to the grip at Q. By pulling on the cord, the finger is released, and the leash slips out of the ring on the cable. Finally, the end of a rope 8 or 10 meters long and from 0.015 to 0.018 meter in diameter which may be called the leash, is permanently at- tached at Q. The other extremity is free, and terminated by an eye. To hook on a boat, the grip lying on the towpath, the finger D free, a man takes the free end of the leash and awaits the arrival of the shackle A (Fig. 82), and passing the leash through the shackle he slips the ring on its free end on to the finger D which he makes fast, so that the grip is arranged as in Fig. 86. A is the towrope, and T the leash, going through the cable shackle. This done he returns to the boat which he has plenty of time to reach before the towrope tightens. If he wishes to stop, he attaches the grip cord to the boat and slackens the towrope, then all the pull coming on the grip cord the spring is compressed, the finger becomes free, and with it the leash. To let go slowly it suffices to slacken the rope on a bitt. But it is more convenient to have a wind- lass with a brake under the steersman's foot; the brake lever is so arranged that he has only to press his foot down to tighten, and to let it go to loosen. Thus the steersman, without quitting his place, by a slight motion of his foot upon the brake casts off from the cable. To slacken speed when in motion, the towrope is slack- ened, but can be hauled m again by the windlass. The windlass is especially useful for this purpose. Thus the slight slowings made necessary by meeting other boats, or passing under bridges, are immediately made up and the journey is made with mathematical regularity. CIVIL ENGINEERING, ETC. 631 (112) Method of circuits . — In an extended application, the circuits may cover without difficulty a distance of from 15 to 18 kilometers, and as the two machines driving two consecutive circuits may he united, it follows that the machines may be from 30 to 36 kilometers apart. The machines thus placed, two and two in the same shed, can mutually help each other in case of accident to either. Continuous towage can go on with slightly diminished velocity, it is true, but with no stoppage. The power used depends on the velocity desired. With a velocity of 0.70 meter per second, the velocity of horse towage, it requires only two horse power to draw a barge loaded with 350 tons, and one horse power for lighter loads. If we adopt the velocity of one meter per second, we must multi- ply these figures by 2.25. One-half a horse power per kilometer should be added for power consumed by the unloaded cable. Under these conditions for a traffic of 1,000,000 tons per year, with a velocity of one meter per second, two machines of from 45 to 50 horse power would be required for each distance of thirty kilometers. (113) The cost of the plant depends on the dimensions of the barges, their number and velocity. Assuming the largest barges 38.50 meters, with a velocity of one meter per second, and a traffic of 1,000,000 tons per year, we may estimate the cost of the plant at 17 francs per running meter. The cost per meter of working, under the severest conditions, and including a sinking fund for the capital, and the cost of renewing the cable not exceeding 3.18 francs, the expense of traction is 0.003 francs per ton per kilometer, if we have a traffic of 1,000,000 tons; it descends to 0.0012, if the traffic amounts to 2,500,000 or 3,000,000 tons. This system has been devised and applied between Paris and Join- ville by M. Maurice Levy, chief engineer of roads and bridges. A system of cable towage differing from the one above described, invented by M. Oriville, is on trial on the Saint Quentin Canal, at Tergniers. Chapter XI. — Towage by a submerged chain, with a fire- less ENGINE. (114) The summit level at Mauvages lies between the two slopes of the Marne and the Meuse ; its length is 9,205 meters of which 4,877 are in a tunnel. The tunnel consists of a full central arch 7.80 meters in diameter,- one side of which is continued by a curved lateral wall; on the other side is the towpath, 1.40 meters wide, protected by a stone revetment. The bottom is about G meters wide. The pool is fed at low water 632 UNIVERSAL EXPOSITION OF 1889 AT PARIS. from the Oruain, 25,000 cubic meters per day, and by a set of pump- ing engines at Vacon, furnishing 40,000 cubic meters, making in all 65,000 cubic meters per day. (115) A system of chain towage has recently been established here with towboats driven by the Francq-Lamb system capable of work- ing without smoke. The Francq-Lamb system, the invention of Lamb and improved by Francq, as it is generally employed on tram- ways, consists in using steam produced from water at a high tem- perature contained in a reservoir fed at some point on the road from a fixed source of supply. It includes, independently of the locomo- tive, a stationary boiler, with a reservoir of superheated steam which may be used at starting, or at some point on the road, to feed the fire- less locomotive. This system thus avoids filling the tunnels with smoke, which would be a serious inconvenience. At the same time the system has been modified by placing the steam boilers as well as the reservoirs on board the towboat. This arrange- ment, would not be thought of for a locomotive, but it presents no difficulty on a boat, as it only occupies 14 or 15 cubic meters of space, and the additional weight is unimportant. (110) Description of the boats (Figs. 87 and 88, A, B, D). — At the bow and on the stern are two guide pulleys for the chain. Two boilers, C, with safety appliances, rated for 17 kilograms of effective pressure. Abaft the engine are the receivers for the superheated water, by which the engine is driven, when the boat is in the tunnel. Above the engine are the drums around which the chain passes. Fig. 88 shows the plan, and Figs. A, B, and D the cross sections through the receivers, through the engine and chain drum, and through the boilers. Each of the two towboats is 29 meters long, 4.65 meters wide, and 2.30 meters deep. The hull is of steel plate; its draught is 1.10 me- ters including coal and water for a trip of 9 kilometers each way. The engine is placed in the middle of the boat; at one end are the boilers and at the other the receptacles for the superheated water. The effective power of the engine, measured on the first towrope, is 18 horses. It is a compound condensing engine with, two inclined cylinders furnished with reversing gear. There are two tubular boilers registered for 17 kilograms effec- tive pressure; each of these is surmounted by a long horizontal steam chamber united to it by large openings; the water level rises just into these chambers which carry all the safety apparatus. On the other side of the engine are the superheated water receivers which, with the generators, furnish the steam requisite tor work- ing the boat through the tunnel. They are steel cylinders sur- mounted by a dome and communicate with the generators by a steam pipe and cock united to the interior of the reservoir with a perforated pipe for heating the water. CIVIL ENGINEERING, ETC. 633 Before it is sent to the cylinders the steam in the receivers is brought to the usual pressure of 5 or G kilograms. The reser- voir for the expanded steam is placed in the interior of the receptacle for the superheated water, thus always affording very dry steam for the cylinders. Figs. 87. and 88. The longitudinal section of the chain tow boats. 634 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The expansion apparatus (for regulating the pressure of the steam to be admitted into the cylinders) is moved by a working beam act- ing on an adjustable lever and completely regulating the use of the expanded steam. The mechanism employed is exactly that used in the Francq loco- motives, except that the generators are carried by the boat instead of being stationary. (117) Daily trips of the boats . — Every day one of the two tow- boats makes a trip. Its speed is 2 kilometers per hour; in the tun- nel it is reduced to 1,500 meters, and often 1,200 meters per hour. Starting at 7 o’clock in the morning, with a pressure of 5 or 6 kilograms, it goes an hour in the open canal, during which the pressure augments to 10 or 12 kilograms, and even 16 or 17 when the load is very heavy. During the passage through the tunnel, which is about 4 hours, the fire is allowed to fall, and the boat is driven only by the steam in the receivers. On coming out of the tunnel the pressure has fallen to 4 or 5 kilograms, which is suf- ficient to finish the journey in the open canal, which usually takes an hour. After an hour for rest the boat returns to the original starting point. During the passage through the tunnel no smoke is emitted, so that it can be seen through from one end to the other. The boat easily tows from twenty to twenty-five barges, carry- ing 4,000 to 5,000 tons of useful load, with the effective work of the engine of from 10 to 17 horse power. The coal burned with a file of sixteen barges attached does not exceed 3 kilograms per horse power, per hour, measured on the tow- rope of the first barge. The toll has been fixed at 0.005 franc per ton per kilometer. The number of hands employed is six — two engineers, two stokers, and two sailors; one of the four in the engine room takes a day off to rest or work in the repair shop. (118) Cost . — The total cost is as follows: Francs. First towboat 120,000 Second towboat 143,000 Chain 49, 000 Sundries 63,000 Total 375,000 The cost of working is about 20,000 francs, which is largely cov- ered by the tolls, which amount to about 24,000 francs derived from a traffic of 600,000 tons per year. The plans were prepared under the direction of the general in- spector, Frdcot, by M. Holtz, chief engineer. CIVIL ENGINEERING, ETC. 635 Chapter XII.— System for supplying the canal from the Marne to the Rhine and the Eastern Canal. (119) Two important groups of pumps serve to supply the canal from the Marne to the Rhine and the Eastern Canal, in that portion between Toul and Mauvages, the summit level of the first canal. These establishments are those of Valcourt, Pierre-la Troiche, and Vacon. (120) The establishments of Valcourt and Pierre-la Treiche are sit- uated on the Moselle, near Toul; they use the falls of the dams con- structed for the canalization of that river, and serve to supply, during the dry season, the great pool, Pagny-sur-Meuse, of the canal from the Marne to the Rhine, where the north branch of the Eastern Canal takes its rise. Each establishment comprises two Fontaine turbines, each driving three horizontal pumps. The connection between the turbines and pumps is made direct by cranks on the hollow shafts of the motors to which the connecting rods of the pumps are attached. (Figs. 89 and 90.) The six pumps of each establishment send their water to a single air reservoir from which the main conduit issues. The data applicable to these establishments are as follows: ^ Height of the fall. Water per second. Power. Min. Max. Min. Max. Meters. Cu. m. Cu. TO. H. P. H P. Valcourt 4 00 3.25 6.00 173 320 Pierre-la Treiche | 2.50 6.50 8. 125 217 270 The heights to which the water, is raised are 40. G5 meters and 40.20 meters. (121) Cost . — Francs. Mach ne and workshop appliances 274, 600. 00 Cost of laying the cast-iron pipes, including the cost of the pipes themselves 248,173.33 Pump houses, land, etc 569, 192.23 Other expenses 542, 297. 75 Total 1,634,262.31 These machines annually raise 5,000,000 cubic meters of water. Allowing 6 per cent as interest and sinking fund, we find 0.48 franc as the cost of raising annually 1,000 cubic meters of water 1 meter. The annual expenses of working 100 days, and repairs, are 20,000 francs; that is, for 1.000 cubic meters raised 1 meter, 0.10 franc; if we add to this the cost of the establishment, 0.48 franc, given above, we shall find the total cost (0.58 franc) of raising 1,000 cubic meters 1 meter. 636 UNIVERSAL EXPOSITION OF 1889 AT PARIS, (122) Establish ment at Vacon . — The other establishment, at Vacon, consists of five boilers, two horizontal steam engines, and two hori- zontal piston plunger pumps, raising 40,000 cubic meters per day a height of 37 meters. The cost of the establishment was 1,250,000 francs. Making the same calculations as before, we find the total cost of raising 1,000 cubic meters of water 1 meter by steam power to be 0.93 franc. The two sets of works were erected under the di- CIVIL ENGINEERING, ETC, 637 ■ rection of Inspector-General Frdcot by Messrs. Poincard, Holtz, Bizalion, and Thoux, chief engineers, and M. Picard, assistant engineer. Fig. 90.— Plan of the pumping station at Pierre-la Treiche. 638 UNIVERSAL EXPOSITION OF 1889 AT PARIS. -if"-.. Chapter XIII. — Oscillating bridge over the Dames Canal Lock. (123) A very common arrangement in canals consists in placing a permanent bridge on the lower end of a iock, using the tail walls as abutments. This arrangement, though economical in construction, is an obsta- cle in working, especially in ascending, by obliging the driver to untackle, that is, to suspend the traction precisely at the moment when the traction should be greatest to overcome the resistances to the boat’s entrance to the lock. To remedy this difficulty a new type of movable bridges has been introduced, called an oscillating bridge. One of these has lately been built over the Dames Lock on the Nivernais Canal, which gives great satisfaction to the boatmen. Fig. 91 shows the principle of the bridge; the hatched edges are sec- tions of the bridge abutments ; A B is the iron roadway movable around a horizontal axle O, placed a few fig. 91-Diagram of the bascule bridge, centimeters back from the abutment face (on the side opposite the towpath), and divided by this axle into two unequal parts O A and O B, the first about double the second. When the roadway is in its normal position the extremity A rests on the abutment on the towpath side, while the other is held on a level with the coping by a particular system of sliding bolts. This abut- ment contains a little depression, so that the roadway may, by tip- ping, take the position A' B '. The towrope passing between A and A' obviates the necessity of untackling, and thus renders the traction continuous. An oscillation in the contrary direction brings back the roadway to its normal position, A B. The roadway has a fixed and a movable counterpoise, and when these are properly adjusted and the sliding bolts pulled out by means of a lever arranged for the purpose the bridge is opened by the weight of a man at B, and by his weight at A closed and locked by the sliding bolts. This system is due to M. B de Mas, chief engineer of roads and bridges. Chapter XIV.— Balanced gates on the Rhone and Cette Canal. (124) The Rhone and Cette Canal crosses the Lez River through a circular basin 50 meters in diameter, 1,500 meters from the mouth of the river in the Mediterranean. Until 1886 the two branches of the canal, one the prolongation of the other through the basin, were terminated by two openings CIVIL ENGINEERING, ETC. 639 reduced to 6.60 meters in width, called semi-locks, which were closed with a plank dam during the time of freshets in the river. These freshets, though short and infrequent, could not be foreseen ; they came frequently at night. The closing of the canal required a number of hands, which were not easily obtained at a short notice, and the work took from three to four hours for each opening. If the openings were not closed in time large quantities of silt were deposited, which on some occa- sions have interrupted the traffic for a month. The annual amount of dredging exceeded 12,000 cubic meters, costing more than 15,000 francs per year on account of the insufficient method of closing the openings. To the effect of the river must be added that of the sea. The water, driven in by gales of wind, is forced up the river like a tide, and, spreading through the openings into the canal, leaves additional masses of sand to be dredged out. The frequency of these storms, together with the impossibility of keeping the openings closed, on account of the traffic, has led to the adoption of balanced gates of a new type at the river crossing. (125) The programme was as follows: To construct at each open- ing a cheap work, utilizing the existing masonry walls and fulfilling the following conditions : First. The openings must be closed at any height of the water by one man in a very short time. Second. They must be able to be opened under a head of from 0.50 to 0.75 meter by two men in a few minutes. Third. The vertical section of the space to be closed is 7.65 meters wide by 3.60 meters high ; the maximum head of water from a freshet to be 1 meter. Fourth. In the normal condition there must be a free passage the whole width, 6.60 meters, of the opening, a draught of 2.40 me- ters, and a vertical opening from 3.80 to 3.90 meters above the water line. Fifth. A final condition for the preservation of the work was that nearly all the pieces of metal or wood, and the mechanical appli- ances, should be normally out of water, and that when immersed they should spontaneously emerge, both for inspection and repair. (126) Description of the gates. — The work consists of a cylindrical sluice turning about a horizontal axle with little friction. This cylin- der has a radius of 3.80 meters and consists of a plate-iron skin 0.008 meter thick, 7.65 meters wide, with a developed length of 4.20 meters along its right section. It is riveted on four horizontal double T flanges 1.05 meters apart. The whole is braced internally by special irons. The end generatrices of the skin are strengthened by lon- gitudinal angle irons ; the one intended to strike against a hurter in the flooring serves, besides, to increase the surface of contact. 640 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The sluice thus constructed is supported at each end by a number of iron double T arms coming together in each side of the opening in the hollow quoin prepared in the masonry for the axle, to which they are united by a cast-iron hub. These arms, four in number on each side, are united at right angles to the corresponding flanges. The junction of the arms with the outer skin and flanges is com- pleted by an iron plate cut in in the form of the segment of a circle and riveted flat upon the arms, and edgewise on the projecting skin, by means of a curved angle iron. The wrouglit-iron axles, 0.25 meter in diameter, are inserted 1 meter above low water into cast-iron hubs, and each one rests on two pillow blocks, one, the bearing pillow block, close to the masonry, the other 2. 50 meters behind. These axles are perpendicular to the chamber walls. To balance the gate around its axle, a cast-iron segment of a rim is placed on each side opposite the sluice, its weight being accurately calculated. Each counterpoise is united to the hub by two arms in line with those connecting the edges of the sluice. This arrange- ment balances the structure if it is completely immersed in air or water. In reality, part must be in and part out of water. At the moment when the lower side of the sluice enters the water, and where the counterpoise emerges, there is produced, in virtue of the Archimedean principle, athruston onesideand adiminutionof thrust on the other, the moments of which add and constitute a consid- erable resistance to the motion, attaining as a maximum 5,000 or CIVIL ENGINEERING, ETC. 641 6,000 kilograms at the distance of 1 meter. This effort, eight or ten times the passive resistance of friction, would destroy the advantages of the system. The following simple arrangement removes the whole difficulty. The additional resisting moment due to the up- ward pressure of the water at any instant will evidently he annulled, if an equal and upward thrust is produced symmetric with the axis of rotation; the total resultant will pass through the axis and tend to lift it, and thereby diminish the friction. A wooden rim completing that formed by the counterpoise and the sluice, calculated so that the moment of its volume per unit of angle shall be equal to the mean moment of the sluice, including the arms, etc., solves mathematically the case of the plane of flotation passing through the axis, and approximately for the case of any plane of flotation. * Each portion of the wooden crown, formed of two segments of one- sixth of the circumference, is united at one end to one of the outside arms of the sluice; and at the other end to an arm of the counter- poise. It is strengthened in the middle by another double T arm fixed to the hub perpendicular to the mean radius of the sluice. Iron hanging ties, strongly stretched, complete the connection and give great stiffness to the wheels thus formed, which are contained in the hollow quoins and thus protected from the shock of the barges. With a view of rendering the closing of the sluice easier than the opening, the theoretical equilibrium has been voluntarily broken, by hollowing those ends of each counterpoise which emerge first during the closing. Finally, the intermediate arms sustaining the wooden crowns, which are horizontal in their normal position, can be fastened on the upstream end by movable wooden wedges, and on the down- stream side, by strong wrought-iron bolts so as to prevent the gate from being accidentally displaced. In closing, the cylindrical sluice strikes its lower edge against an oak hurter 2.10 meters below low- water mark, and the upper edge is at 1.50 meters above that limit. (127) The opening and closing are easily effected by means of two chains passing around a groove in the rim of the wooden crowns and counterpoises and pulled in one direction or the reverse by means of chain pulleys worked by windlasses. Generally the wind- lasses are thrown out of gear. To start the gate, the wedges are re- moved, the bolts opened, and one of the windlasses is put in gear and worked (by one man, who makes the opening in forty or sixty seconds ; to open the gate under a head of 0. 50 or 0. 75 meter, both windlasses are used, and two men, one on each side, effect the opera- tion in five or six minutes. * This ring being there for the sake of its volume, and not for weight or strength, the use of wood is naturally indicated. H. Ex. 410 — VOL III 41 642 UNIVERSAL EXPOSITION OF 1889 AT PARIS. This apparatus solves completely the problem, and assures rapid opening and closing of the two openings in times of freshet or high tide. Although recently established, there has been considerable diminution in the silting, and in the interruptions in the traffic. These interruptions were formerly for several consecutive days per year, now, they amount to a few hours for each freshet, and general- ly the boats can pass notwithstanding* an ordinary freshet. The solution is therefore perfectly satisfactory. (128) Cost. — The iron frame-work of the two gates with their accessories, hurters, windlasses, etc., including the cost of setting up, amounted to 27,295.54 francs. It was begun in 1885 and finished in 1887. The plan was made, and the work executed by M. Guibal, engi- neer, under the direction of MM. Delon and Lenthdric, successive chief engineers. Chapter XV.— Braye-en-Laonnois Tunnel. (129) An example of the use of compressed air in tunnel construc- tion. — The canal between the Oise and the Aisne passes through the ridge separating the basins of these two rivers, by a tunnel 2,360 meters long, the bottom being at a distance of 122 meters below the highest point. The geological formation is that portion of the Tertiary known as the Eocene, and the stratum the Suessonian. This Suessonian stratum is made up of a layer of plastic clay between two layers of sand, viz, the Soissonnais above and the Bracheux below. Above the Soissonnais sand comes the Paris chalk which constitutes the ridge. The tunnel is driven through the lower layers of the Suessonian; but near the head on the Oise slope the layers form a pocket, the point of which, 300 meters from the head, penetrates the crown of the tunnel for a distance of 0.30 meter into the layer of Tertiary Soissonnais sand. The water filtering through the upper sands ac- cumulates upon the layer of clay, and at the beginning of the work filled the ground for a height of 15 or 16 meters, and rendered these sands, which are very fine, liquid. Also, the water soaked into the upper part of the layer of plastic clay, which, besides the imperme- able clay beds, contained permeable beds of lignites and agglomera- tions of shells. In these formations on the Oise slope the driving of the tunnel presented the greatest difficulties, increasing as the thickness of the clay roof, which served as a protection against the fluid sand, dimin- ished. At each instant thin layers of clay, intercalated between the lignites and the shell agglomerates, kept breaking, resulting in cav- ings in and inpourings of sandy mud, stopping the work. (130) Use of compressed air . — To remedy this state of things it was proposed to use compressed air, and the plant for this purpose 643 CIVIL ENGINEERING, ETC. was thus set up near the head. It consists of seven portable engines of 220 horse power, driving eight compressors, which, furnish to the working chamber, every 24 hours, 50,000 cubic meters of air under a pressure of 1 kilogram above the atmosphere. ' 1 1 1 l-M . . 1 1 1 o 10 xo 30 So 50 _ O *00 X 00 100 *100 Soo too JO 0 Soj yoo iooo* Fig. 93.— Geological section of the range of hills between the Oise and Aisne valleys through the axis of the tunnel. The upper layer is miry clay: the next is limestone rock; then Soissonnais sand down to the dark stratum: the curved line, marked 101, denotes the water level. Below the sand is a stratum of dark clay containing lignites, which ignited when the water was driven off. Below this is a stratum of compact blue clay, and just in a pocket projecting down into the tunnel is a mass of Soissonnais sand. Below the blue clay is a mass of Braeheux sand. The portion of the tunnel giving the greatest difficulty and requiring the use of compressed air is situated between 185 and 450 meters from the head. In front of the machinery building a series of reservoirs was set up of 91 cubic meters’ capacity, with the air at a pressure of from 4 to G kilogrammes (absolute pressure) which served, especially in the beginning, to drive out the excavated material, as will be ex- plained presently. 644 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The working chamber at the face of the tunnel was formed by a masonry wall, perforated by air locks (Fig. 95) giving admittance to and exit from the chamber. (131) The first wall or dam was 10 meters thick and 120.50 meters from the head ; but the second, which was at 187 meters from the head, will be here described, as it was an improvement on the first: Fiq. 94.— Details of the construction of the tunnel. Longitudinal section along the axis A B of the tunnel. Horizontal section plans along A B and O P. Cross sections C D, E F, G H, I J, K L, M N. CIVIL ENGINEERING, ETC. 645 This dam was formed by a wall 6.70 meters thick above and 8 me- ters below, so as to contain the lock and pieces of frame work, which had to project into the working chamber. It was constructed of bdton held by masonry walls. Five openings were made, three below and two above, the lower ones only being supplied with locks, the upper ones being closed by a stone wall. « Sections of the air lock. Fig. 95— A, air-supply pipe; B, pipe enclosing the electric wires; C, pipe inclosing the telephone wires; D, pipe for discharging the excavation spoil; E, drain pipe; F, entrance of the high-pressure air pipe, used to blow out the excavation spoil. Fig. 96 is the section through the broken line A B. The lower cylinder is the air lock ; the curved tube, marked F, at one end was used to blow out the excavation spoil. Each lock was 8 meters long, 1.65 meters wide, and 2.20 meters high ; it was provided with a lining consisting of wrought iron rings, with India rubber washers, bolted together, and with two air tight doors closing against seats faced with India rubber, one opening from the outer air into the lock, and the other from the lock into the chamber; the latter could be opened from within the lock or from the working chamber by means of a double set of levers for that purpose. Above each door, cocks were placed, one on the inte- rior and one on the exterior of the lock, for the introduction or escape of the compressed air. (132) Mode of removing the excavation sjioil . — The lock had a small railroad track, and cars could be carried through it; four pipes also passed through it, two above and two below. These pipes, 0.40 meter in diameter and inclined O.05 meter per meter, ended in the working chamber by an upward bend into which the spoil was thrown. Each end of this pipe was tightly closed by a stop valve. The exterior valve being closed, the pipe was filled from the interior, then closing the interior valve, opening the exterior, and at the same time opening a cock, putting the curved portion of the pipe in connection with the pipe bringing air from the reservoirs at a pressure of at least 4 kilograms, this pressure drove out the spoil in a few seconds. The exterior valve was then closed and the opera- tion repeated. 646 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Two drain pipes 0.35 meter in diameter passed through the lock on the floor; they had cocks which served for the drainage of the chamber, the water being driven out by the compressed air. Gramme dynamos, driven by a 15 horse-power engine, supplied the Edison lamps for lighting the chamber, and a telephone united it with the central office. Great difficulties were found in keeping the working chamber tight. The compressed air forced its way out over the extrados of the arch, between the masonry and the earth, along poling boards required for supporting the ground, and also through the masonry joints. It was only by building a masonry buttress, from 40 to 50 centimeters thick, that the pressure in the chamber could be brought up to 1.8 or 2 kilograms, under which condition the arch was com- pleted, for a distance of 200 meters from the head, at the rate of 12 or 15 meters per month. (133) Accidents by fire . — In August, 1884, the work was arrested by an accident which cost the lives of seventeen workmen. The compressed air had penetrated into the pyrites lignites, driven off the water, and oxidized the pyrites; the heat thus produced had ignited the lignites, and the gas from this combustion had asphyx- iated the victims. (134) Accessory constructions . — To reestablish access to the lock another issue was opened for the products of the gas combustion, by making six vertical bore holes, starting from the outside and carry- ing them to the points where the fire was most active. On the other hand, the finished part of the tunnel was ventilated by compressed air carried into the air lock and allowed to escape. After awhile the air became pure, and on the 4th of October the ground in the work- ing chamber was shored up, and on the 30tli the forced ventilation by compressed air was discontinued. The surface water, no longer kept back, penetrated to the seat of the fire and extinguished it; but this water remained hot a long time; six months after, that which trickled through had a temperature of 30° C. It was at this time that the lock was transferred from 120.50 to 187 meters from the head, as above described. As the combustion of the lignites was always to be feared, provi- sion was made for securing an active ventilation through the whole of the open tunnel, by sinking a shaft a little on one side and con- necting it with the crown of the arch by a short inclined drift 109 meters from the head. This shaft was closed at the top and pro- vided with a Pelzer fan 1.80 meters in diameter, with a minimum exhausting capacity of 15 cubic meters per second. (See Fig. 97). That the suction of the fan should be felt in front of the lock the tunnel was divided into two unequal parts by a vertical longitudinal wall 1.80 meters from the right wall of the tunnel surrounding the ventilation mouth, and prolonged to within 4 meters of the lock. CIVIL ENGINEERING, ETC. 647 The work with compressed air was recommenced, but it was very difficult to keep up the pressure, and it was determined to interrupt the construction for a certain length and begin 20 meters farther on, so as to leave a massive dam of unbroken ground between the old and new chamber. For this purpose both compartments of the old working chamber were closed by masonry walls. To permit the continuation of the work, three arched galleries were driven, two below on a level with the flooring, and one above (Fig. 94), but the upper one had to be immediately closed on account of leaks. The lower galleries being driven through clay, no leaks were perceived after they had been lined with masonry, one for 24.50 meters and the other for 10.25 meters of their respective lengths. The pressure went up as the work advanced from 2.3 to 2.4 kilo- grams with two-thirds of the motive power, and this was the normal pressure used in completing the work. In this way the driving of the lower galleries continued until the bottom of the pocket, 300 meters from the head, had been passed, then they turned back 648 UNIVERSAL EXPOSITION OF 1889 AT PARIS. toward the head and constructed the arch upon the abutments built by the aid of the lower galleries. This step was successful, and allowed the work to be finished. Details of the ivork . — While the lower arched galleries were being driven the lower story of the abutments of the arch between the references 63.20 and G5.85 meters was built ; then, when the galleries were recommenced, by means of timbering they constructed in the same way the lower story, which formed one of the side walls of the gallery. In the beginning, the other wall on the shaft side was simply protected with poling boards, but the swelling of the clay which broke the timbers, reduced the section, and stopped the running of the cars, obliged them to build on this side a wall 0.G0 meter thick, strengthened by spurs 1 meter thick and 1.50 meters apart. These little walls were constructed for the whole length of the lower gal- leries. These galleries also served to construct another story of abutments between the references 65.85 and 68.40 meters, which was built by means of a gallery driven astride the lower abutment; see Fig 04, section KL. The communication between the two galleries was made by the space between the timbering, by taking out the horizontal shores between two frames. This upper gallery was open for a length of 10 meters at a time ; they laid the masonry abutments at one end, and drove the gallery at the other, changing the connecting apertures with the lower gal- lery as they advanced. As soon as the masonry work was finished, they filled the rest of the gallery with blocks of dry stone so as to allow no space. This work went on at the rate of 1.50 meters per day, occasionally interrupted by the ignition of the lignites. When they arrived at a point 397 meters from the head a rise was put in, and a length of 4 meters of the arch completed. From this point the work was carried on in both directions, but principally toward the Oise, at the rate of 12 meters per month. The layer of fluid sand extended 0.50 meter into the top of the upper gallery, but it had become so dry by the action of the com- pressed air, that they were able to put in the crown packing planks, one at a time, after making a space with a spade and driving it in with a mallet. The water did not begin to run until these planks were put in, and owing to the opening of the lower galleries its level had fallen 5 or G meters, which facilitated the work. While the work of finishing the arch toward the Oise continued, it was slowly progressing toward the Aisne. On the 25th of Septem- ber, 1888, the arch having been completed to 409.50 meters, the use of compressed air was discontinued and, on account of the rising of the beds of clay, the rest, up to 450 meters, was finished without it, by taking proper precautions. (135) Cost . — The first 450 meters of the tunnel were finished in Octobei*, 1888, and cost 6,720 francs per running meter. CIVIL ENGINEERING, ETC. 649 The work was done under the direction of M. Boeswillwald, chief engineer of roads and bridges, and M. M. Guillon and Pigache, assistant engineers. Chapter XVI. — Navigation of the Seine from Paris to the sea. (136) At the beginning of the century the navigation of the Lower Seine was often interrupted by low water and by freshets. Great diffi- culties and even dangers-were encountered in passing the bridges and dams. Ascending only by horse towage, consuming from Rouen to Paris fifteen days for ordinary freight, and four or five for accelerated freight, the boats were rarely able to be loaded to their full depth, from 1.80 to 2 meters. The cost of freight was 16 francs per ton from Rouen to Paris, and the annual traffic did not exceed 77,000,000 kilometric tons. Without undertaking to describe the improvements made in the navigation of the river before 1878, it is sufficient to say that with the works recently constructed, many of which have been described in detail, the river between Paris and Rouen has been divided into nine reaches by the construction of locks and dams, with a minimum draught of water of 3.20 meters, and no difficulties are experienced either from low water or the passage of locks. The towpaths are in order, but they have been abandoned, the transport being made by steam, either by freight boats or towboats; the journey is made by the former in 28 hours, and by the latter, towing a convoy, in 3 days. The price of freight, which was from 12 to 15 francs per ton in 1840, 10 to 12 in 1859, 8 to 9 in 1869, is now from 4 to 5 ascending, and from 2.75 to 3.50 francs descending, and will diminish progressively as new boats are built to utilize more completely the improvements of the route. Indeed, the traffic* since the completion of the canalization, has considerably augmented. The total tonnage between Paris and Rouen, including that taken on the way, was in 1881, 227,307,266 kilo- metric tons, and in 1888 it was 389,668,346. (137) Cost . — The cost of the works of canalization amounts to 88,553,000 francs. If we compare this total expense with the actual traffic we find the interest at 5 per cent on the first cost, divided by the number representing this traffic to be, 5 x- 8S — 000 = 0.011 100 389,568,346 per kilometric ton, and it is certain that the cost of freight has diminished very much more than that. All the works constructed from 1878 to 1888 were directed by MM. de Lagrend, Bould, and Camere, chief engineers. * M. Camere pointed out to the author a new steamer of 600 tons burden, built for the coasting trade, just returned from a voyage to Spain. 650 UNIVERSAL EXPOSITION OF 1889 AT PARIS. .2 £ ■ — 0> A O C CIVIL ENGINEERING, ETC. 651 Chapter XVII — Embankment works for the improvement of the tidal Seine. (13?) The object of the improvement of the tidal Seine is to facili- tate the access of vessels to the port of Rouen, situated 125 kilometers from the sea. Of this distance half required improvements to render it navigable, and this comprised the parts between La Mailleraye and the sea below Honfleur. The breadth of the river bed between La Mailleraye and Villaquier was 1,000 meters, at La Vacquere 1,500 meters, at Quillebeuf 3,000, below La Roque 7,000, and above Hon- fleur 10,000 meters (Fig. 98). (138) Depth of ivater . — This vast extent of water was filled with banks of shifting sand, which were constantly changing place through the action of the strong currents of the ebb and flow of the tide, and it often happened that in the course of a few days the position of the channel would be shifted from one side of the river to the other. The depth was also variable and insufficient. During the highest tides there was a depth of 4.30 meters below Quillebeuf, and only 1.76 meters at high neap tides, and many dan- gerous rocks and shoals impeded the navigation above this point. These perils encountered at intervals of the voyage were considera- bly augmented by the tidal wave or bore, and vessels were stranded by its powerful action without the possibility of receiving assistance. Under these circumstances the navigation was confined to vessels of from 100 to 200 tons burden. The voyage from the sea up to Rouen occupied four days; a great number of wrecks marked the route, freights between the sea and Rouen rose to 10 francs per ton, and the rate of insurance was one-half per cent. (139) Improvements . — Such was the state of things in 1848, when the improvements were begun, which consisted in building training walls, sometimes on one side, sometimes on both sides, extending from La Mailleraye to the mouth of the Risle, a distance of 43 kilo- meters. The distance between the training walls was 300 meters at La Mailleraye, and gradually increased to 500 at the Risle. Tow- paths were built between La Mailleraye and Rouen. The works were finished in 1867 and cost about 14,000,000 francs. These training walls are constructed of random work built of blocks of chalk taken from the cliffs on the banks of the river ; some are raised above the level of the highest tides, while others are capable of being submerged, so that they may have less influence in promoting the accumulation of deposits. High walls are used on the right bank as far as Tancarville, and on the left as far as La Roque. Beyond these points the walls are low. At La Roque the top of the wall is 1.34 meters above low water at neap tides, and 2.10 meters above low water at the spring tides. The right embank- ment is 0.45 meter higher than the left. 652 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The stones from the neighboring quarries were soft and subject to the action of frosts, currents, and particularly the tidal wave or bore, a powerful volume of water preceding the flood tide, rushing up the river, and dashing against the banks with great violence ; this has undermined and sometimes destroyed the original walls. (140) New improvements . — Very extensive repairs, or rather re- constructions, which are yet going on, were necessary, which bring up the total cost of the walls to the sum of 2S, 000, 000 francs since the beginning. In these reconstructions the same materials are em- ployed, but to protect them against the frost and the bore they have been covered by a facing 0.25 meter thick. To defend the base against being undermined at the places where the bore is violent, a concrete apron was built, 3 meters wide and 0.40 meter thick, secured with piling and planking on its outer edge. The cost of the walls thus reconstructed amounts to 250 francs per running meter. These reconstructions, begun in 1880, are rapidly progressing, and already from 25 to 30 kilometers are finished ; they were indispensable and will make the walls last a long time. (141) Alluvial land . — Behind the training walls, and in parts for- merly occupied by the shifting sands, alluvial meadows have been formed to an extent of over 8,400 hectares in 1880. They are divided into three classes : land made over to the river- side proprietors ; land belonging to the state, and land in the course of formation. First. The state made over 2,613 hectares to the river-side proprie- tors and received an indemnity of 1,398,200 francs. Second. An area of 3,710 hectares yields a profit to the treasury every year by rent of the pasturage, which in 1878 amounted to 295,575 francs. Third. An area of 2,077 hectares is in the course of formation. These meadows are of excellent quality, and they are actually worth 4,000 francs per hectare. When all the alluvial lands now forming are definitely constituted, the total value of the lands thus reclaimed will be 33,600,000 francs. Finally,, it should be under- stood that these calculations only include the lands above the actual limit of the training walls, and that the influence of these works extends a long distance beyond them into the estuary. (142) Results . — The results have surpassed all anticipations. The channel has become fixed and deepened between the walls more than 2 meters, so that vessels of 2,000 tons can navigate the river, the depth being at low tide 5.50 meters and at high tide 6.50 meters. The charge for freight between Havre and Rouen has been reduced one-half, that is, to 5 francs per ton, and the insurance for Rouen is the same as for Havre. The traffic has consequently increased from 500,000 tons in 1860 to 1,600,000 tons in 1888. (143) The effects of the training walls have been confined to the channel between them, but their deepening influence extends little CIVIL ENGINEERING, ETC. 653 beyond their extremities. The estuary channel is constantly shift- ing. In M. Vautiers report he traces on the chart of the estuary twelve totally different locations of the main channel beyond the walls, from 1874 to 1880. A prolongation of the southern bank below the Risle was carried out in 1870, but a proposed prolongation of the northern bank was refused, and the works finally stopped, for fear of endangering the approaches to Havre, the second port of France, by the silting up of the estuary. (144) The following account by Prof. Vernon-Harcourt, the emi- nent hydraulic engineer, of his experiments on a model of the lower Seine created great interest among the members of the Congress for Inland Navigation at its Paris session in 1889, and its author made, by special invitation, a Report on the Canalization of Rivers and the Different Systems of Movable Weirs. THE PRINCIPLES OF TRAINING RIVERS THROUGH TIDAL ESTUARIES.* The conditions affecting the training of rivers in the nontidal portions of their course by jetties, or rubble embankments designated as training walls, are well understood. Training walls substitute a straightened uniform channel for irregu- larities and varying widths, improving the flow of the current and rendering it uniform, so that scour occurs in theshallow, narrowed portions, and more uniformity of depth is attained. In very winding rivers, the additional precaution has to be taken of somewhat reducing the width where the deepest channel shifts over from the concave bank on one side to the concave bank on the opposite side at the next bend lower down, so as to reduce the shoal which is found near the point of con- trary flexure by concentrating the current at this place. The training of the outlets of sediment-bearing rivers into tideless seas is deter- mined by the same principles; for a definite discharge is directed and concentrated between training walls or piers, so as to scour a channel across the bar formed, in front of the outlet, by the accumulation of deposit dropped by the enfeebled issuing current. The increased velocity of the current through the contracted outlet car- ries the silt into deeper water, where it is either borne away by any iittoral current, or again forms a bar, after a lapse of time depending on the depth, which can be removed by an extension of the training works. The training also of the upper part of the tidal portion of rivers has been effected on similar principles to the nontidal portion, with satisfactory results, even though the problem is, in this case, complicated by the changes in the direction of the cur- rent, and the requisite maintenance of the tidal capacity. In the lower parts, however, of tidal rivers, where the tidal flow predominates, it is difficult to determine the proper width for a trained channel, which, while nar- row enough to secure an adequate depth . should not very materially check the tidal flow to the detriment of the outlet. Moreover, where the estuary is large, consid- erable doubt may exist as to the best direction for the training walls ; and the estab- lishment of training walls in a wide estuary, where the flood tide ischarged with silt, has resulted in extensive accretions,! and corresponding reduction of tidal capacity, by the concentration of the tidal flow and ebb in the trained channel, and a conse- quent enfeeblement of the currents at the sides, favoring deposit. The principles, indeed, upon which the training of tidal rivers should be based are in a very un- - * From the proceedings of the Royal Society, Vol. 45, p. 504. f Instit. Civ. Engin. Proc., Vol. 84, pp. 246 and 295, and Pis. 4 and 5. 654 UNIVERSAL EXPOSITION - OF 1889 AT PARIS. defined and unsatisfactory condition, as exemplified by the conflicting opinions of engineers whenever important training works through estuaries are proposed, as exhibited with reference to the schemes for training works in the upper estuary of the Mersey,* for which the. Manchester Ship Canal promoters sought powers in 1888 and 1884, and as at present exist about the extension of the training works in the Kibble estuary. (■ This is due to the various conditions involved, which differ more or less in each case, and thus render it difficult to lay down general rules for guid- ance from arguments based on analogy. One of the most important considerations is the form of the estuary ; and in this respect no two estuaries are alike, as their form is the result of complex geological and hydrological conditions ; and it suffices to contrast the Mersey and the Kibble, the Dee and the Tay, the Clyde and the Tees, the Seine and the Loire, to indicate the varieties of forms which may have to be dealt with. Other circumstances affecting the problem are the rise of tide, the tidal capacity and general depth, the fresh-water discharge, the silt introduced by the flood tide or brought down by the river, the condition of the sea bottom in front of the mouth, and the direction in which the tidal current enters the estuary. The positions also of ports established at the sides of estuaries require special considera- tion in determining the proper line for a trained channel. These numerous and variable conditions have often led engineers to enunciate the opinion that each river must be considered independently by itself. This view, however, if strictly ad- hered to, by excluding the experience derived from previous works, would prevent any progress in the determination of general principles for the improvement of navigation channels through estuaries; each training work would form an inde- pendent scheme, based upon no previous experience, and might or might not pro- duce the results anticipated by its designer. Unfortunately also it is impossible to proceed with training works by the method of trial and error ; for besides the cost of modifying the lines of training walls, if the desired results are not produced, these works generally effect such extensive changes in an estuary that it would be impracticable to restore the original conditions, or to modify materially the altered position. (145) It might be possible to deduce general rules for training works from a care- ful consideration of a variety of types of estuaries, especially those in which train- ing works have been carried out ; and I have commenced an investigation of this kind. This method of inquiry, however, requires a variety of data which it is difficult to obtain for most estuaries, and must depend upon a careful estimate of the relative influence of each of the variable conditions, and a train of reasoning from analogy which might not be accepted by engineers as conclusive. Accord- ingly, it would be of the very highest value to river engineers, and of considerable interest from a scientific point of view, if a method of investigation could be de- vised which might be applied to the special conditions of any estuary, and the results of any scheme of training works determined approximately beforehand in a manner which could be relied upon from the fact of their depending on an assimi- lation to the actual conditions of the case investigated, and noton arguments based upon the effects of similar works under more or less different conditions. The fol- lowing description is therefore given of the results of investigations, carried on at intervals during more than two .years, with reference to the proposed extensions of the training works in the Seine estuary, which appear to afford a fair assurance that a similar method, applied to any estuary would indicate the effect of any scheme of training works, provided the special conditions of the estuary were known. * Evidence before select committee of Lords and Commons on the Manchester ship canal bills, sessions 1883 and 1884, and Instit. Civ. Engiu. Proc., Yol. 84, p. 309, Fig. 7. + Instit. Civ. Engin. Proc., Vol. 84, p. 260, Fig. 1. CIVIL ENGINEERING, ETC. 655 INVESTIGATIONS ABOUT THE SEINE ESTUARY. (146) The training works in the lower portion of the tidal Seine, commenced in 1848, had reached Berville in 1870, when the works were stopped, in the interests of the port of Havre, on account of the large unexpected accretions which were tak- ing place behind the training walls, and at the sides of the wide estuary below them.* The original scheme, proposed in 1845 by M. Bouniceau,t comprised the extension of the trained channel to Honfleur on the southern side of the estuarv, and the prolongation of one or both of the training walls towards Havre at the northwestern extremity of the estuary, as in any scheme the interests of both these ports, on opposite sides of the estuary, have to be considered. The works are acknowledged to be incomplete ; and great interest has been evinced, particularly within the last few years, in the question of their extension, so that the shifting channel between Berville and the sea may be trained and deepened, and the access to Honfleur improved, without endangering the approaches to Havre. The objects desired are distinctly defined, but the means for attaining them have formed the subject of such a variety of schemes that hardly any part of the estuary below Berville has not been traversed by some proposed trained channel, except the por- tion lying north of a line between Hoc and Tancarville points, which is too far removed from Honfleur to be admissible for any scheme. Altogether, including distinct modifications, fourteen schemes have been published in France within my knowledge, seven of them having appeared within the last five years. The schemes also exhibit great varieties in their general design } (Figs. 99, 101, 102, 103, and 105), illustrating very forcibly the great uncertainty which exists, even in a special case where the conditions have been long studied, as to the principles which should be followed in designing training works. It is evident that no reasoning from analogy could prevail among such very conflicting views; and having had the subject under consideration for a long time, the idea occurred to me in August, 1886, of attempt- ing the solution of this very difficult problem by an experimental method, which might also throw light upon general principles for guidance in training rivers through estuaries. The estuary of the Seine is in some respects peculiarly well adapted for such an investigation, for old charts exhibit the state of the river before the training works were commenced, and recent charts indicate the changes which the training walls have produced, while the various designs for the completion of the works, proposed by experienced engineers, afford an intereresting basis for exper- imental inquiries into the principles of training works in estuaries. If, in the first place, it should be possible to reproduce in a model the shifting channels of the Seine estuary as they formerly existed, and next, after inserting the training walls in the model as they now exist in the estuary, the effects produced by these works could lie reproduced on a small scale, it appeared reasonable to assume that the introduction, successively, in the model of the various lines proposed for the exten- sion of the training walls would produce results in the model fairly resembling the effects which the works, if carried out, would actually produce. (147) When the third Manchester ship canal bill was being considered by Parlia ment, in 1885, Prof. Oborne Reynolds constructed a working model of the por- tion of the Mersey estuary above Liverpool on behalf of the promoters of the canal, with the object of showing that no changes would be produced in the main chan- nels of the estuary by the canal works, which have been designed to modify very slightly the line of the Chesire shore above Eastham. This model was, I believe, the first experimental investigation on an estuary by artificially producing the tidal *Instit. Civ. Engin. Proc., Vol. 84, p. 241, and Pis. 4 and 5. , + Etude sur la Navigation des Rivieres a Marees, M. Bouniceau, p. 152, PI. 2. Jlnstit. Civ. Engin. Proc., vol. 84, p. 247, and PI. 4, Fig. 9. G56 UNIVERSAL EXPOSITION OF 1889 AT PARIS. action of flood and ebb on a small scale, and Prof. Reynolds’s experiment showed that a remarkably close resemblance to the main tidal channels in the inner estuary could be produced on a small scale. As the Mersey model did not extend into Liverpool Bay, the tidal action produced was very definitely directed along the confined channel representing the “ Narrows” between Liverpool and Birkenhead; and this tidal flow was not perceptibly influ- enced by the relatively very small fresh- water discharge. In the Seine, however, there is no narrow inlet channel to adjust exactly the set of the flood tide into the estuary ; and the fresh-water discharge of the Seine, with a basin about eighteen times larger than the Mersey basin, forms an important factor in the result. The tide in a model of the Seine has to he produced in the open bay outside the estuary at a suitable angle which had to be determined ; and it was essential for the success of the Seine experiments that accretion should be produced in the model of the Seine estuary under certain circumstances, which was a condition which did not enter into the Mersey problem. Accordingly, the very interesting and valuable re- sults obtained by Prof. Reynolds, in his model of the Mersey, could afford no assurance that experiments involving essentially different and novel conditions would lead to any satisfactory results. I therefore restricted the requirements for my experiments within the smallest possible limits, and contented myself with the simplest means, and the limited space available in my office at Westminster. (148) Description of model of the Seine estuary . — The model representing the tidal portion of the river Seine and the adjacent coast of Calvados, extending from Martot, the lowest weir on the Seine, down to about Dives, to the southwest of Trou- ville, was molded in Portland cement by my assistant. Mr. Edward Blundell, to the scales of horizontal and ?ki 3 vertical. The first is the scale of some of the more recent published charts of the Seine — and even at that scale the model is nearly 9 feet long — whilst I made the vertical scale one hundred times the horizontal, as the fall of the bed of the tidal Seine is very slight, and the rise of spring tides at the mouth, being 23 feet 7 inches, amounted to an elevation of the water in the model of only 0.71 inch. There are two banks at the mouth of the estuary, between Havre and Villerville Point, known as the Amfard and Ratier banks, which emerge between half tide and low water, and divide the entrance to the estuary into three channels. Through all the changes in the navigable channel at the outlet, these banks always appear in some form or other in the low-water charts, either connected with the sand banks inside the estuary or detached. On examining the large chart drawn from the survey made by M. Germain in 1880, I found that rock and gravel cropped up to the surface over a certain area on these banks, and accordingly I in- troduced solid mounds at these places to represent the hard portions of the Amfard and Ratier banks, which are permanent features in theestuary. As a rocky bottom is found near Havre, and also at Villerville Point on the opposite side of the outlet, Amfard and Ratier banks are doubtless the remains of a rocky barrier which in remote ages stretched right across the present mouth of the river. Where the rocky bottom lies bare, near Havre and Villervile, the model was molded to the exact depths shown on the chart of 1880: but in other places the cement bottom was merely kept well below the greatest depth the channel had attained at each place, whilst the actual bed of the estuary in the model was formed by the flow of water over a layer of sand. (149) Arrangements for tidal and fresh-water flow. — The mouth of the Seine estuary faces west, but the tidal wave comes in from the northwest, and the earliest and strongest flood tide flows through the northern channel between Havre and the Amfard bank ; whilst the influx through the southern Villerville channel occurs later, and is stronger toward high water. Accordingly, the tidal flow had to be in- troduced from a northerly direction, at an angle to the mouth of the estuary ; and the line of junction of the hinged tray, producing the tidal rise and fall, was made CIVIL ENGINEERING, ETC. 657 at an angle of about 50° to a line running from east to west in the model, so that the tidal flow approached the estuary from a point only about 5° to the west of north- west. The tray was made of zinc, inclosed by strips on three sides to the height of the sides of the estuary ; and it was hinged to the model, at its open end, by a strip of india-rubber sheeting along the bottom and sides, so as to make a water-tight joint with sufficient play at the sides to admit of the tray being tipped up and down from its outer end. The rise and fall of the tray was effected by the screw of a letter press, from which the lower portion had been detached, by raising and lower- ing the upper plate of the press, half of which was inserted under the tray. After the requisite amount of sand had been introduced to raise the bottom to the aver- age level, the model was Filled with just enough water for the surface of the water to represent low water of spring tides when the tray was down and the screw at its lowest limit ; and the tray was madeof such a size that, when the screw was raised to its full extent, the water in the model was raised, by the tipping of the tray, to the level representing high water of spring tides. The water representing the fresh- water discharge of the Seine was admitted into the upper end of the model from a tap in a small tin cistern ; and the efflux of a similar quantity of water was pro- vided for at the lower extremity of the estuary, on its northern side near the tray, by a cock with a larger orifice placed at such a level as to allow the water to How out into a second cistern, of similar size, during the higher half of the tide. (150) First results of working the model . — The construction of the model wascom- menced in October, 1886, and its working was commenced in November. Though the Portland cement was convenient for molding in a small space and in the absence of appliances, it did not prove satisfactory for retaining water at first. The model was purposly made in two halves, and the straight joint was subsequently made water-tight; but, nevertheless, era 'ks occurred at various places through which the water leaked, and they had to be repaired as they appeared ; and the bottom of the model was eventually coated with thick varnish, and after a time the leaks ceased. The flexible india-rubber hinge, from which I had anticipated some trouble, leaked very little from the beginning, and on being fitted with greater care in introducing a tray of somewat different form, no leakage occurred. Silver sand was used in the first instance for forming the bed of the estuary'. From the outset the bore at Caudehec indicated by a sudden rise of the water, and the reverse current just before high water near Havre, called the “ verhaide ,” were very well marked. The verhaule is evidently a sort of back eddy, on the northern shore, occasioned by the influx of the tide, and by the final filling of the estuary from the southern channel ; whilst the bore appears to result from the concentra- tion of the tidal rise by the, sudden contraction of the estuary above Quillebeuf. The period given to each tide in working was about twenty-five seconds, which ap- peared fairly to reproduce the conditions of the estuary.* After the model had been worked fora little time, the channels near Quillebeuf assumed lines resembling those which previously existed, and a small channel appeared on the northern shore, by Harfleur and Hoc Point, which is clearly defined in the chart of 1834. The main channel also shifted about in the estuary and tended to break up into two or three shallow channels near the meridian of Berville, where the influencesof the flood and ebb tides were nearly balanced. The model, accordingly, fairly reproduced the condi- tions of the actual estuary previous to the commencement of the training walls, though the channel in the estuary diil not attain the depth, as represented by the proportionately large vertical scale, which the old channels possessed, owing, doubt- less, to the comparatively small scouring influence which the minute currents in * According to the formula in the paper by Prof. O. Reynoldson his Mersey model, read at the Frankfort Congress in August, 1888, the tidal period would be nearly twenty-three seconds. H. Ex. 410 — VOL III 42 658 UNIVERSAL EXPOSITION OF 1889 AT PARIS. the model possess. The sand, in fact, can not be reduced to a fineness corresponding to the scale of the model, whilst the friction on the bed is not diminished equiva- lently to the reduction in volume of the current. Silver sand has been used on account of its being readily obtained, its purity, and absence of cohesion, as it was hoped that the water by percolating freely through it would more readily shift it. A film, however, seemed by degrees to form over its surface, reducing considerably its mobility, and as the action of the water on it consisted merely in rolling the particles along the bottom, this sand did not prove satisfactory for producing the requisite changes when the training walls were inserted in the model. It became, therefore, essential to search for a substance which the water could to some extent carry in suspension for a short period. (151) Trial of various substances for forming the bed of the estuary. — Some sub- stance was required, not necessarily sand, insoluble in water, easily scoured, and therefore not pasty or sticky, and sufficiently tine or light to be carried in suspen- sion to some extent by the currents in the model, and not merely rolled along the bottom like the silver sand. A variety of substances of low specific gravity, and in powdered form, were accordingly tried in succession during the first half of 1887. Pumice in powder proved too sticky, and flour of sulphur was too greasy to be easily immersed in water. Pounded coke was too dirty to be suitable, and particles of it floated. Violet powder became too pasty in water, and fuller’s earth and lupin seed exhibited similar defects. The grains of coffee grounds were too large in water, and moved up and down in the currents too readily, whilst fine sawdust from box- wood and lignum vitae swelled in water and was carried along so very easily by the stream that no definite channels were formed in it. The powder obtained from Bath brick, which was experimented upon for some time in the model, both with- out and with training walls, yielded more satisfactory results, as. besides affording shifting channels like the silver sand, it accumulated at the sides of the estuary when the training walls were introduced in the model. It, however, gradually be- came too compact, so that the current could no longer produce much effect on it; but as it is probable that some sticky material is used in the manufacture of Bath bricks, it is quite possible that if I had succeeded in my endeavor to obtain the silt of the river Parrot, from which the bricks are made, in its natural state, the mate- rial might have proved more subject to scouring influence. At last, in July, 1887, I found a fine sand, on Chobham Common, belonging to the Bagshot beds, with a small admixture of peat. This sand, besides containing some very fine particles, was perfectly clean, so that water readily percolated through it; and it accordingly combined the advantages possessed by silver sand with a considerably greater fineness. (152) Results of working model with Bagshot sand. — The bed of the estuary hav- ing been formed with the sand obtained from Chobham Common, after the model had been worked for some time, the channels assumed a form very closely resem- bling the chart of the Seine estuary of 1834.* Accordingly, the first stage of the investigation was duly accomplished by the reproduction of a former state of the estuary in the model, with the single exception of a decidedly smaller depth in the channels, except in places where the scour was considerable; which is readily ac- counted for by the circumstances of the case. It is probable that with a larger model, and especially if the bed was not so nearly level as in the Seine, the depth would approach nearer to the proper distorted proportion as compared with the width. The close correspondence of the channels in the model with an actual state of the estuary in its natural condition, confirms, in a considerably more complicated case, the results previously achieved by Prof. Reynolds with reference to the upper estuary of the Mersey, and affords a fair certainty that, with adequate data, the natural condition of any estuary could be reproduced on a small scale in a model. *Instit. Civ. Engin. Proc., vol. 84, Plate 5, fig. 1. CIVIL ENGINEERING, ETC. 059 Introduction of the existing training walls in the model . — The second stage of the investigation consisted in the introduction of training walls into the model, corresponding in position to the actual training walls established in the estuary down to Berville. These walls, formed with strips of tin, cut to the corresponding heights at the different places, and bent to the proper lines, were gradually inserted in sections ; and the model was worked between each addition, to conform, as far as practicable, to the actual conditions. The fine particles of the sand accreted behind the training walls, and the channel between the walls was scoured out, corresponding precisely to the changes which have actually occurred in the estuary of the Seine. The foreshores at the back of the training walls were raised up in some parts to high-water level, whilst in other places the accumulation was some- what retarded by the slight recoil of the water from the vertical sides of the model, and by the wash over the vertical training walls, these forms being necessitated by the great distortion of the vertical scale of the model. On the whole, however, the accretion and scour in the model correspond very fairly to the results produced by the existing training walls in the estuary. Tiie accretion, moreover, in the model, extended beyond the training walls on each side, down to Hoc Point on the right bank, obliterating the inshore channel close to Harfleur, which had been repro- duced in the model, and down to Ilonfleur on the left bank, corresponding in these respects also to the actual changes in the estuary.* The main channel also, beyond the ends of the training walls, was comparatively shallow, and was unstable, repro- ducing the existing conditions in the estuary. The experiments relating to this stage extended over a year and a half, taking, up all the time that could be spared to them by myself and my assistant during that period ; they formed the turning point of the investigation, and have the inter- est of being, as far as I am aware, the first attempt at putting training walls in a model, and obtaining the resulting accretion on a small scale. Without the accom- plishment of this stage, it would have been useless to continue the investigation; and its satisfactory attainment proved so difficult in actual practice, that for a long time it seemed probable that the attempt must be abandoned. (153) Application of system to ascertain the probable effects of any training works . — As the first and second steps in the investigation, by the aid of the model, had furnished results which corresponded very fairly with the actual states of the estuary of the Seine before and after the execution of the training works, the final stage of the investigation, for ascertaining the probable results of any extensions of the training walls, could be reasonably entered upon. In selecting the lines of training walls to l>e experimented on, it appeared expedient to adopt those which have been designed, after careful study, by experienced engineers, both on account of the results from these being far more interesting than those of a variety of theo- retical schemes, and also in the hope that some assistance might thereby be ren- dered to French engineers in the prosecution of this important work. Moreover, the schemes exhibit sufficient variety to admit of their being taken as types of schemes for throwing light upon the principles on which training works should be designed in estuaries. Accordingly, the third stage in the investigation consisted in extending the training walls in the model, in accordance with the lines of some of the schemes proposed ; and, after working the model for some time with each of the extensions successively, the several results were recorded, as shown in figs. 1)9-106. The lines of training walls experimented on in the model were taken, with one exception, from five out of the seven most recent schemes proposed, as these five schemes are, I believe, the only ones which are still put forward for adoption. The lines shown on Fig. 107, represent merely a theoretical arrangement of train- ing walls, inserted for a final experiment in the model, to ascertain the effect of *Instit. Civ. Engin. Proc.,vol. 84; compare plate 5, fig. 1, and plate 4, fig. 1. 660 UNIVERSAL EXPOSITION OF 1889 AT PARIS. the most gradual enlargement of the trained channel which the physical conditions of the estuary would have admitted of at the outset, whilst maintaining the full width at the mouth. (154) Scheme A . — The first arrangement of extended training walls introduced into the model taken from a scheme, some of the main features of which were pro- posed in an earlier scheme in 1859,* and which was put forward in an amended form in 1886. f The design, as inserted in the model, consisted of an extension of the parallel training walls from Berville down to Ilonfleur, and the formation of a breakwater across the outlet, from Villerville Point, on the southern shore of the estuary, out to the Amfard bank, thus restricting the mouth to the channel between Amfard bank and Havre. The lines of these works were formed in the model with strips of tin. as shown on Fig. 99; the northern training wall was kept low, and the southern wall was raised to the level representing high water of neap tides; whilst the strip representing the breakwater was raised above the highest tide level, thus forcing all the flood and ebb water to pass through the Havre Channel. The results obtained in the model with these arrangements, after working it for about six thousand tides, are indicated on the first chart (Fig. 99). The channel be- tween the prolonged training walls had a fair depth throughout, partly owing to the concentration of the fresh-water discharge between the walls, and partly from the retention of some additional water in the channel at low water, by the hindrance to its outflow offered by a sandbank which formed in front of the ends of the train- ing walls. A deep hole was soon scoured out in the narrowed outlet by the rapid flow of the water filling and emptying the estuary at every tide. The absence, however, of connection between the direction of the flood tide current through the outlet and the ebbing current from the trained channel, aided by the accretion of sand in the sheltered recess behind the breakwater, led eventually to the formation of two almost rectangular bends in the channel, one just beyond the training walls and the other near Hoc Point, in the model. This tortuous channel, moreover, was shallow, except at the bends and the outlet, and a bar was formed a short dis- tance beyond the outlet. The contraction of the mouth of the estuary by the breakwater interfered so much with the influx of the tide into the estuary as to render it impossible to raise the tide inside to its previous height, and the reduction in height of tire tide was clearly marked at Tancarville Point in the model. Sedi- ment accumulated in the estuary beyond the trained channel, being brought in by the rapid flood current, and not readily removed by the ebb, except in the trained channel and near the outlet; and this accretion, by diminishing the tidal capacity, gradually reduced the current through the outlet, and consequently the depth of the outlet channel. A considerable accumulation of sand took place outside the breakwater, along the southern seacoast, so that the bank opposite Trouville in the model was connected with the shore, and the foreshore advanced towards the end of the breakwater (Fig. 99). (155) Scheme B . — The second arrangement of training walls inserted in the model below Berville. was taken from a scheme proposed in 1888. representing a modifica- tion by another engineer of the design from which Scheme A was copied. | It comprised the retention of the breakwater from Villerville Point to the Amfard bank, the most essential feature in Scheme A; but the extension of the northern training wall was dispensed with, whilst the southern training wall was prolonged, *“ La Seine comtne Voie de Communication Maritime et Fluviale,” J. de Coene, 1883, p. 11, and plate 7. f“ Projet desTravaux a faire a la’Embouchure de la Seine.” L. Partiot, Paris, 1886. | Memoires de la Societe des Ingenieurs Civils, Mars, 1888, Paris, pp. 257 and 273, and PI .162, Fig. 2. CIVIL ENGINEERING, ETC. 661 in a continuous curve, from Berville to Honfleur (Fig. 100), and eventually to the Amfard bank, connecting it there with the extremity of the breakwater (Fig. 101.) TR0UVH.Lt Fig. 99.— Scheme A.* A slight widening out of the existing trained channel by an alteration of the end portion of the northern training wall, completed the arrangement of the model. 'uLUVmi Fig. 100— Scheme R. The results obtained by inserting the training wall down to Honfleur, and then working the model for about 3,500 tides, are shown in Fig. 100; and those obtained Fig. 01— Scheme B 2 . after the prolongation of the southern training wall to the breakwater, and work- ing the model for about 3,700 tides, are shown in Fig. 101. The channel followed pretty nearly the concave line of the prolonged southern training wall, between 1 1 £P/i ILE "The existing training walls stop at Berville. 662 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Berville and Honfleur. in the model, except near Berville; but the depth of water was less regular than in the previous experiment, owing to the diminished concen- tration of the ebb from the absence of the northern training wall. The channel between Honfleur and Ainfard was tortuous as before, but its direction was differ- ent. The deej) hole at the outlet, the bar beyond, and the advance of the southern foreshore beyond the breakwater, reappeared again with very similar features to those in the first scheme, except that the sandbank did not quite reach the outside face of the breakwater at low water. (Compare Fig. 100 with Fig. 99.) (156) The results which followed from working the model with the southern training wall prolonged to Amfard are shown in Fig. 101. The main alteration from the former experiment naturally occurred between Honfleur and Amfard in the model, a continuous channel being formed along the new piece of concave training wall; whilst the general depth inside the estuary was improved as far as the meridian of Hoc Point. The channel, however, above Honfleur was not im- proved, owing apparently to the want of uniformity between the directions of the flood and ebh currents in the model. The other features remained very similar to tin 1 former case, except that the end of the sand bank beyond the breakwater was slightly eroded, whilst deposit took place between the extended training wall and the breakwater. (Compare Fig. 101 with Fig. 100.) Fig. 102. — Scheme C. (157) Scheme C.— The third arrangement of training walls experimented upon in the model was chosen from a design published in 1885.* It consisted of an en- largement of the original trained channel below Quillebeuf, by a modification of the southern training wall from Quillebeuf, and of the northern training wall from Tanearville, and the extension of the northern wall to Amfard and Havre, and the southern training wall to Ratier, as shown on Fig. 102. The trained channel was thus given a curved, gradually enlarging form, and was directed into the central channel of the model, between Ratier and Amfard, the Villerville and Havre chan- nels being practically closed near low water. The effects of working the model for about 6.500 tides with this arrangement of training walls are indicated on the chart (Fig. 102). The main channel kept near the concave southern training wall for some distance below Berville, and then gradually assumed a more central course between the training walls towards the outlet, passing out just to the south of the Amfard bank. The channel thus formed had a good, tolerably uniform depth, together with a fair width, owing apparently to the flood and ebb tides produced in the model following an unimpeded and fairly similar course. Deposit occurred behind the training walls on each side; and the foreshore advanced in front of Trouville in the model, inconsequence of the shutting up of the Villerville Channel. * La Seine Maritime et son Estuaire, E. Lavoinne, Paris, 1885, p. 140, and Instit. Civ. Engin. Proc., Vol. 84, p. 248, and PI. 4, Fig. 9. CIVIL ENGINEERING, ETC. 663 (158) Scheme D . — The fourth arrangement of training walls adopted in the model was selected from the most recent design* proposed by an engineer who had pre- viously submitted schemes in 1881f and 18864 The trained channel was widened out by an alteration of the southern wall from Quillebeuf, and the northern wall from Tancarville, more than trebling the width between the training walls at Ber- ville in the model; and the walls were extended in sinuous lines to Havre on the northern side, and Honfleur on the southern side, as shown on Fig. 103, thus form- ing a winding trained channel rapidly enlarging near its outlet. The model, with Fio. 103.— Scheme D. these lines of training walls, was worked for about 5,000 tides, with the results indi- cated on the chart. Deep channels were scoured out close along the inner concave faces of the training walls in the model; but shoals appeared over a considerable area of the newly trained channel; a bar stretched across the deep channel where it shifted over from the south to the north training wall, about half way between Berville and Ilonfleur; and a large sand bank, emerging above low water, occupied the center of the outlet opposite Honfleur. Deposit also occurred at the sides of the estuary behind training walls. (159) As it was of importance to ascertain to what extent accidental modifications in the arrangement of the sand in the preparation for an experiment might affect Fio. 1(M.— Scheme D bis. the result, the lines of training walls described above were inserted a second time in the model, after the subsequent scheme E had been experimented upon, render- * Deposition de M. Vauthier devant la Commission des Ports et Voies Navigables de la Chambre des Deputes, Paris, 1888, p. 17, and PI. 4. t Rapport sur les Ameliorations dont sont encore susceptibles la Seine Maritime et son Estuaire, L. L. Vauthier, Rouen. 1881, p. 16. and Annex 29. | Dire a l'Enquete ouverte sur l'Avant-projet des Travaux d'Amelioration de la Basse-Seine, 1886, L. L. Vauthier, Paris, PI. 1. 664 UNIVERSAL EXPOSITION OF 1889 AT PARIS. ing it necessary to replace afresh both training walls, and to remodel the sand so as to represent approximately the present condition of the estuary. The model was prepared for this second experiment in the usual way, without any special endeavor to secure coincidence with the first experiment in the initial arrangement of sand banks and channels. The condition of the low-water channels in the model, after working the model with this arrangement of training walls for the second time for about 5,400 tides, is shown on Fig. 104. The main features of the trained channel in the charts of the two experiments exhibit a very fair resemblance, considering the modifications which any alterations in the initial condition might produce, and the naturally variable state of the channels in a wide outlet. The deep channels reappear in the second chart at the inner concave faces of the training walls, with intervening shoals; a large sand bank is again visible at low water along the north training wall opposite La Roque and Berville in the model; anil the sand bank in the center of the outlet of the trained channel opposite Honfleur emerges again, though smaller in extent owing to alterations in the channel; and the deep place at the end of the southern training wall close to Honfleur is the same in both charts. (160) Scheme E . — The fifth arrangement of training walls introduced into the model was taken from a design* published in 1888, which is a modification of a Fig. 105. — Scheme E. scheme, presented in 1886, by a committee of experts appointed by the French Gov- ernment to consider the question. f In the scheme as laid down in the model the trained channel in the bend between Quillebeuf and Tancarville, where the depth was greatest, was enlarged in width by setting back the southern training wall; the original width of the channel was retained at the point of inflection opposite Tancar- ville, and the channel was widened out below La Roque by a modification of the lines of both training walls down to Berville. The training walls were also extended beyond Berville in sinuous lines, as shown on Fig. 105, the southern wall being car- ried down to Honfleur, and the northern Wall not quite so far. The portion form- ing the last bend of the northern training wall was kept low, whilst the others were made high, according to the design. Both in this and the preceding arrange- ment of training walls experimented on the expanding trained channel was some- what restricted in width along the portions near the changes of curvature, to make it conform to the principles which experience has laid down for training winding rivers in their nontidd course, as previously mentioned. The results obtained, *De l’Amelioration du Port dil Havre et des Passes de la Basse-Seine. Baron Quinette de Rochemont, Paris, 1888, excerpt Memoires de la Societe des Ingenieurs Civils, 1888, p. 334, PI. 162, Fig. 1. f Commission d’Etude des Ameliorations a apporter an Port du Havre et aux Passes de la Basse-Seine — Raport de la Commission, Paris, 1886, p. 61, and chart. CIVIL ENGINEERING, ETC. (i<>5 after working the model for about 3.700 tides, are represented on the chart (Fig. 10. r >). The channel between the training walls was somewhat shallow in places, and though a deep channel was formed along the inner concave face of the south- ern wall between La Roque and Berv lie, a shoal emerging above low water appeared along the concave face of the last bend of the northern training wall. This bank appeared to be due to the protection the extremity of the bend afforded from the action of the flood tide in the model, whilst the ebb followed the central Hood-tide channel, instead of passing over to the concave bank, as would have occurred with the current of a nontidal river. The main channel beyond the training walls, which, though of fair depth, was somewhat narrow and winding, was also unsta- ble, for in the early part of the experiment its outlet was in the central channel between Ratier and Amfard in the model, whilst at the close of the experiment it had shifted, as shown, to the Havre Channel. Accretion occurred behind tin- train- ing walls in the model, and some silting up took place in the Villerville Channel and along the foreshore in front of Trouville, owing apparently to the preference of the main channel for the other outlets, and the diminished capacity of the estuary resulting from accretion. (101) This arrangement of training walls was further investigated by workingthe model for about 0,300 tides more, with the results shown on Fig. 106. The chief fea- tures of the estuary in the model showed only slight changes from the state previ- Fio. 106. — Scheme K bis. ously recorded (Fig. 105), with the exception of the main channel, which had shifted again to the central outlet, whilst the northern foreshore above low water extended over part of the former site of the channel. The two conditions of the estuary, represented by Figs. 105 and 106, have therefore the interest of exhibiting in the model a shifting channel such as actually exists at the present time in the Seine estuary below Berville. (162) Scheme F . — The last experiment was made on an arrangement of training walls inserted in the model, making the trained channel expand as gently as practi- cable between Aizier and the sea, whilst retaining the natural width at the outlet (Fig. 107). This is the form of channel which theory indicates as the most suitable.* for whilst it facilitates the influx of the Hood tide, it prevents, as far as possible, the abrupt changes in the velocity of a river in passing from its estuary to the sea. which are so prejudicial to uniformity of depth in a channel. It was therefore of interest to ascertain what results would be produced by this theoretical arrangement of training walls in the model, which, in order to leave the outlet free, and thus avoid favoring a progression of the foreshore outside, had to provide a wide channel near Honfleur compared with the restricted width available at Quillebeuf. The di- rection of the channel between Aizier and Quillebeuf, together with the cliffs bor- dering the river at Quillebeuf and Tancarville Points, determined the maximum width obtainable at Quillebeuf and the direction of the channel from Aizier to Tan- Rivers and Canals, L. F. Vernon-Harcourt, p. 236. UNIVERSAL EXPOSITION OF 1889 AT PARIS. 666 carville; and the extension of the training walls in the model from this point was regulated by the necessity of passing close to Honfleur at the south, and not im- peding the approach to Havre on the north. The effects produced in the model by working with this arrangement of training walls for al>out 7,300 tides are indicated on the chart ( Fig. 107). The southern training wall was kept above high-water level all the way to its termination at Honfleur in the model, hut the northern training wall was gradually reduced in height from nearly opposite Honfleur towards Havre. The trained channel had a good width at low water throughout, in spite of the dis- tance apart of the training walls in the model, the whole channel being below low-water level, except near the southern wall between Berville and Havre, and against the northern wall nearly opposite Hoc Point, where banks emerged slightly above low water. The channel, moreover, was distinctly, though slowly, improv- ing with the continuance of the working, and the banks diminishing. There was also a fair depth in the channel, the shallowest place being opposite Berville, whilst a deep place was formed just above, near the southern wall between La Roque and Berville. The depth in all the outlet channels was well maintained; and though deposit naturally took place behind the northern training wall, no accretion was visible along the foreshores outside. Fig. 107.— Scheme F. CONSIDERATIONS AFFECTING EXPERIMENTAL TRAINING WORKS. (163) The value of experiments resembling those just described depends entirely upon the extent to which they maybe regarded as producing effects approximately corresponding, on a small scale, to those which training works on similar lines, if carried out in an estuary, would actually produce. If the effects of any training works could be foreshadowed by experiments in a model, the value of such experi- ments, in guiding engineers towards the selection of the most suitable design, could not be overestimated. Some of the influences at work in an estuary can not possibly be reproduced in a model — such as winds and waves. Winds coming from different quarters are va- riable in their effects; but the direction of the prevailing wind indicates the line in which the action of the wind has most influence, which may be exerted in reenforc- ing the flood or ebb currents, and may aid or retard accretion bv blowing the silt- bearing stream more into or out of the estuary. Waves are the main agents in the erosion of cliffs along open seacoasts, and in stirring up sand in shallow places; and the material thus put in suspension may be transported by tidal currents, aided by wind, into an estuary, and be deposited under favorable conditions. These cir- cumstances affect the rate of accretion, which can not be investigated experiment- ally, as it is impossible to reproduce in a model the proportion of silt in suspension, which, moreover, varies in any estuary with the state of the weather and tide, and the volume of fresh water discharged. Inside an estuary, also, waves in storms may erode the shores at high tide, and modify the low-water channels; but the first CIVIL ENGINEERING, ETC. 667 effect is very gradual, and the second is intermittent, only occasionally occurring. The main forces acting in any tidal estuary are the tidal ebb and flow and the fresh-water discharge, which are constantly at work; and they regulate the size of the channels in an estuary, and for the most part their direction, as well as the limits of accretion. These are the forces which can be reproduced in miniature in a model, as proved by the close concordance in the channels obtained by experiment with the actual conditions of the Mersey, and with a previous state of the Seine estuary; and this similarity of results would not have occurred if the other influ- ences noticed above were at all equally potent. Training walls mainly modify the direction and action of the tidal ebb and flow and fresh-water discharge; and therefore it is reasonable to suppose that the re- sults in a model, due to these alterations, would correspond to their actual effects in an estuary, provided the important element of accretion could be also reproduced. This was satisfactorily accomplished in the second stage of the investigation, prov- ing that the miniature influences produced in the model corresponded, in this case also, with the forces acting in the estuary. Accretion is promoted by training walls in an estuary where matter is carried in suspension; but the action of waves in modifying the channels is stopped by the intervention of training walls. Accord- ingly, the further the training walls are extended, and the more an estuary is pro- tected by works such as those indicated in Figs. 99-101, the more is the modifying influence of waves eliminated, and therefore the more are experiments in a model likely to correspond with the conditions of estuaries under similar conditions. (104) Other considerations also afford grounds for supposing that the effects ob- served with training walls in a model fairly correspond with the results which such works would produce in an estuary. The chartsof the experiments show that defi- nite results followed from certain lines inserted in the model, and that modifications in these lines were followed by modifications in results. (Compare Figs. 99-101 and Fig. 103 with Fig. 105.) Moreover, the results produced with the model agree very closely with the results which, in the two earliest schemes experimented upon, it was stated, before the experiments were begun, would follow, if the works indi- cated by lines in the charts were actually carried out in the Seine estuary.* * Compare the observations relating to Scheme A and Fig. 99, with the follow- ing extract from Instit. Civ. Engin. Proc., vol. 84, p.356: “Thenarrowing of the mouth of the estuary of the Seine would at first promote scour, and increase the depth in that part of the. channel, and for a little distance above and below. This contraction, however, would impede the influx of the flood tide, and cause changes in the velocity of the current through the narrow neck, and in the wide estuary above, promoting the deposit of silt brought in by the tide. This accretion would be greatly aided by the prolongation of the training walls to Ilonfleur, so that eventually the greater portion of the estuary comprised between Tancarville, Hoc Point, and Honfleur would be raised to high-water level. This large reduction in tidal capacity would reduce the tidal current through the narrowed entrance, and consequently diminish again the depth in the channel. Moreover, this reduction of tidal flow in and out of the lower estuary would favor the natural heaping-up action of the sea on the sands outside: so that eventually, not only would the initial deep- ening of the narrowed outlet be lost, but the good depths in the bay outside the estuary would be imperiled.” Compare also Fig. 102, with the following extract from Instit. Civ. Engin. Proc., vol. 84, p. 250: “The continuously concave southern training wall, whilst very favorable to Honfleur. will unduly keep the ebb current to that side, and there- fore away from Havre. Also, the extension of the wall along the Ratier Bank will act like a groyne, and, arresting the silt-bearing southern current, will connect Trouvilie Bank with the shore, and lead to a large accumulation of deposit in front of Trouville. * * * and also the low walls proposed will not prevent accretion.” 608 UNIVERSAL EXPOSITION OF 1889 AT PARIS. It would be impossible to determine by experiment the time any changes in an estuary would occupy. The figures, in fact, giving the number of tides during which each experiment was worked, are not even intended as an indication of the rate of change in the model, and much less as any measure of the period required for such changes in an estuary, but merely as a record of the comparative duration of each experiment. It was observed, however, that the changes were most rapid where the modifications effected by the lines of walls inserted in the model were greatest (Figs. 99-101), and slowest where the lines in the model produced the least altera- tions. (Figs. 102 and 107.) PRINCIPLES FOR TRAINING TIDAL RIVERS DEDUCED FROM EXPERIMENTS. (165) The foregoing investigations, viewed merely as experiments, without any reference to their hearing ou the Seine, may serve for indicating some general prin- ciples applicable in training tidal rivers through wide estuaries. Direct experiment for each estuary is undoubtedly preferable to abstract reasoning, where such experi- ment is possible, as it reproduces the special conditions of the estuary to lie in- vestigated. Nevertheless general principles may be of value in guiding the choice of designs to be investigated, so as to avoid waste of time in testing unfavorable schemes, and also in cases where the conditions of an estuary are not sufficiently known to afford a correct basis for experiment. The experiments may be divided into three classes, namely: (1) Outlet of estuary considerably restricted, and channel trained inside toward outlet. (Figs. 99-101.) (2) Channel trained in sinuous line, expanding towards outlet, but kept somewhat narrow at changes of curvature. (Figs. 103-106.) (3) Channel trained in as direct a course as practicable, and expanding regularly to outlet. (Figs. 102 and 101.) The experiments of the first class exhibited a deep outlet, and a fairly continuous channel inside, where the training works were prolonged to the outlet. The chan- nel, however, was irregular in depth near the outlet; and a bar appeared in front of the outlet outside. The breakwater also, extending across part of the outlet, fa- vored deposits both inside and outside the estuary, by producing slack water in the sheltered recesses. The second class of trained channel was designed to profit by the scour at the concave face of bends, so clearly exhibited at the first bend of all the charts, and to continue the depth thus obtained by restricting the width between the bends, on the principle adopted for winding nontidal rivers. Experiment, however, did not bear out the advantages anticipated from this system, probably owing to the varia- ble direction of the flood tide at different heights of tide, its being checked in its progress by the winding course, and not acting in unison with the ebb from the dif- ference in its direction and the width of the trained channel near the outlet. The main stream in a nontidal winding river always follows a tolerably definite course; whereas the flood tide tends gradually, as it rises, to assume as direct a course as possible. The difference, therefore, in the conditions of a nontidal and tidal river, in this respect, is considerable. (166) The third class of trained channel afforded a wide, tolerably uniform chan- nel in the experiments; the flood tide was less impeded in its progress than with the other forms of training walls, and appeared to act more in concert with the ebb. Tie experiments, accordingly, indicate that the only satisfactory principle for training rivers, through wide estuaries with silt-bearing currents, is to give the trained channel a gradually expanding form, with as direct a course as possible to the outlet. The rate of increase of width between the training walls must la* de- termined by the special conditions of the estuary. If the outlet is very wide and the gradual expansion in width can not be commenced a considerable distance CIVIL ENGINEERING, ETC. 669 up an estuary, some restriction in width at the outlet may be expedient to avoid a too-rapid expansion. It is evident that the widening out adopted in the last experi- ment (Fig. 107) was carried to its utmost limits, from the continuance of sand hanks inside the trained channel, and that, regarding merely the improvement of the channel, it might have been preferable to restrict its width at the outlet as effected in Scheme C (Fig. 102). At the same time it must not be inferred from the ex- istence of these sandbanks that the distance apart of the training walls was much too great in the last experiment; for the width apart of the training walls necessi- tated the inclusion of a greater extent of sand banks within the trained channel at the outset, and also rendered the rate of improvement in the channel more gradual, so that the improvement in the channel both in direction and depth was still pro- gressing at the close of the experiment, and the sand banks in the channel were in process of removal and not being formed. The choice in such cases, where the widening. out can not be commenced far up, appears to lit* between the utmost im- provement of the channel at the expense of accretion on the foreshores outside and the maintenance of the depths over the foreshores beyond the outlet, accompanied with a somewhat less good channel in the estuary. In some cases, deposit on the foreshores at the side beyond the outlet might be of no importance, and then the river channel should be primarily considered; but if, on the contrary, accretion on the foreshores outside is undesirable, the outlet must be maintained by a greater widening out of the training walls. The actual direction of the training walls must be determined, in each case, by the general direction of the channel above, the situ- ation of ports on the estuary, the position of the outlet, and the set of the flood tide at the entrance. (107) Concliuiing remarks . — In terminating this record of my investigations and the general principles for training works which they seem to indicate, I desire to acknowledge the care with which my assistant, Mr. E. Blundell, lias carried out the tedious task of working the tides in the model, and prepared the charts of the ex- perimental results from which the illustrations accompanying this paper have been drawn out. Eddies at sharp edges, due to distortion of scale, appear to have exces- sive scouring effect in a model; whilst the action of the more regular currents ex- hibits a deficiency in scouring power, as previously noted. Though the actual depths of the channels, however, are too small for the distorted vertical scale, re- liance, I think, maybe placed on the general forms and relative depths of the chan- nels obtained in a model. It is possible that the inadequate depth might he reme- died by the employment of a finer or lighter material for forming the l>ed of the model, or by using a liquid of greater density than water; but sand and water have the unquestionable advantage of being the substances which actually effect the changes in estuaries. PART II— TIDAL, COAST, AND HARBOR WORKS. Chapter XVIII. — Calais Harbor Works. (108) In 1875, before the beginning of the improvements just fin- ished, the condition of the port was as follows: The depth in the outer channel on the bar, maintained by the action of the littoral currents and that of the sluicing basin, varied from zero to 0.75 meter below the zero of the charts (this zero being the mean level of the Medi- terranean at Marseilles). The other depths below this datum were as follows: Channel between the jetties. 1.50 to 2.50 meters below zero. At the foot of the wharf built against the western jetty for the channel mail steamers, 3 meters below zero. In the outer harbor, 0.72 meter above zero. In the dock, 0.72 meter above zero. Total length of the quays, 2,330 meters. Area of the western dock, 2 hectares. The entrance lock to this dock, 17 meters wide, had a single pair of gates, and could only be used by vessels during one or two hours of high tide. The rise of the tide is about 7 meters. The width of the quays did not anywhere exceed 30 meters, which was entirely too narrow for the traffic along the Calais-Dover route, requiring, as it did, branch lines, sidings, and facilities for transporting the freight between the ships unloading and the Calais station. Also, there were no adequate means of communication between the port and the network of water ways connected with it, so that in 181 5 the total tonnage entering and leaving the port was 840,000 tons, but the weight of merchandise imported and exported did not ex- ceed 215,000 tons. For want of sufficient depth on the bar the mail service between Dover and Calais was the only one which could be run at fixed hours day and night, and even this was more or less irregular. The new works, created in virtue of the laws of December 14, 1875, and August 3, 1881, which are now completed, have wholly changed 670 CIVIL ENGINEERING, ETC. 671 the condition of the port from what it was 14 years ago. These new works (see Fig. 103) may be described as follows : (169) Exterior and interior channel. — By dredging, and bv the combined action of the two sluicing basins, a minimum depth of 4 672 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (170) Scouring or sluicing basin. — The sluicing basin lias an area of 90 hectares ; it has been excavated to a depth of 5 meters above the zero of the charts, except in the center where a deeper channel has been made to the opening of the sluicing lock. The volume of available water stored at high tide above the ref- erence + 5 is 1,000,000 cubic meters. This volume can be dis- charged, with a fall of from 4.25 to G meters, in from 45 to 00 min- utes. (171) The sluicing lock is made with five openings, each 0 meters wide, closed by balance gates turning around a central axle The sill of these openings is placed at low-water level,— 0.72 meter. The sluicing water is so directed as to strike upon the inner channel, 250 meters from the extremities of the jetties, where a great deal of sand is deposited, and where the dredging is difficult. The sand is cur- ried to the bar, whence it is easily removed by dredges. (172) Outer harbor. — The new outer harbor has an area of 0 hec- tares; it is bordered on the northeast and southwest by quays which are connected by return walls to the entrance lock of the eastern dock. The mean width is 100 meters, and the depth 4 meters below zero, except at the foot of the southwestern quay, where the channel is cut 7 meters deep to allow large ships to remain afloat. This quay is 240 meters long, and its foundations are sunk 10 meters below zero. Here sheds are built and rails laid for the use of ocean steamships, so that they can call at Calais, and can load and unload without entering the dock. The northeast quay is for the steamboat service between Calais and Dover, and contains the railroad station, and berths for four steame-rs from 100 to 120 meters long, drawing 3.50 meters. The quay itself is 370 meters long and has a depth of 3.5 meters at its foot. (173) Eastern dock . — Entrance to the eastern dock is obtained by means of two parallel locks whose sills are placed 1.75 meters below zero ; their depth is 5. 70 meters below the mean sea level (3. 92 meters) and their widths are 21 and 14 meters, respectively; they will lock ships 135 meters long, and are each divided by a pair of intermediate gates, so as to economize the water when locking small vessels. At high tide vessels can go through the locks. The gates, capstans, drawbridges, etc., are worked by hydraulic machinery. The area of this dock is 12 hectares, including the inner basin, with which it communicates. Its width is 170 meters at the entrance, 120 at its southern extremity, and 70 in the inner basin ; close to the locks the width is increased so as to give more room to vessels entering or leaving. The depth is 0.50 meter below the sills. The total length of the quays around this dock is 1,500 meters. The inner basin is excavated to low-water level, and the effective length of the surrounding quays is 350 meters. The width of the western quay is 100 meters and that of the eastern 140. CIVIL ENGINEERING, ETC. 073 (174) Sheds are constructed on the west side by the chamber of commerce, and all quays are provided with railroad tracks by the Northern Railroad Company. (175) Graving dock . — A dry dock 155 meters long, entered through a lock, can accommodate vessels 150 meters long. It is provided with pumping machinery arranged so as to empty the dock in 3 hours. (17G) Canal dock . — Between the east and west docks is a canal dock, covering 4 hectares, for the use of barges; it is surrounded by a quay 1,000 meters long, and extends from the new eastern dock, with which it is connected by two locks, to the citadel canal, by which it communicates with the citadel lock and the old port. Communication between this dock and the citadel lock can be cut. off by means of a guard lock, the gates of which may be moved whatever may be the force of the current, thus forming a dam in case of accident to the citadel lock, either against the sea or against the water in the dock. (177) The Pierrettes canal runs into the citadel lock below the guard lock. It may be used to separate the old sluicing basin from the drainage canal. The gates of the guard lock are closed against the water in the basin, when the Pierrettes canal is used to discharge its flood waters into the sea through the citadel lock, the level of this canal being 1 meter below the Calais canal. The Pierrettes canal is usually kept closed by a movable dam. Five bridges, two of which cross the locks, provide for the traffic between the two sides of the canal. (178) The Marck canal, which receives nearly all the surface water from the lowlands on the right^of the Calais canal, formerly dis- charged through a bridge dam into the Calais canal, in the center of the town of St. Pierre. The water could run into the sea through the citadel lock only when the latter was being emptied. These waters w r ere so abundant as to require the level in the Calais canal to be frequently and excessively lowered. To avoid this and pre- serve a constant level in the Calais canal in times of freshet, the Marck canal has been diverted so as to discharge directly into the outer harbor. The Calais canal has also been straightened, enlarged, and deepened so as to allow the passage of vessels of 300 tons burden, the largest that can be accommodated on the northern water ways between Belgium and France. (179) The Calais improvement works began in 1870. The sluicing basin and its lock, the outer port, the lock of the eastern dock, and the northern part of the basin itself, had to be constructed on the beach. The southern portion of the same dock had to be excavated across the line of downs and the works which protected the town of St. Pierre from the sea situated about 2 meters above the highest tide. All the excavations had to be made in the tine beach sand H. Ex. 410— vol in 43 <674 UNIVERSAL EXPOSITION OF 1889 AT PARIS. and downs, and upon it the harbor works had to rest. Again the foundations could not be made without protection against the sea. Fortunately the contour of the port and the general arrangement of the works permitted the formation of a series of coffer dams, cor- responding to several groups of projected improvements, which •could be undertaken separately. The utilization of the first fillings for the quays and permanent dikes as coffer dams, greatly reduced the amount of temporary earthwork. The slopes, slightly exposed to the sea, were covered with rocks from the chalk formation and held by wattling. When more exposed, they were covered with sand resting on straw so placed that the stalks lay in the direction of the greatest slope, and were held by horizontal lines of wattling; between these lines the straw was loaded with hard limestone, pointed and laid in courses with their tails downward, and strongly rammed to- gether. In the most exposed portion the revetment of the slope was formed by stone pitching. The foot of the slope rested against a line of sheet piling which was reinforced by a mass of beton sunk 1.50 meters in the sand. The stone pitching was laid upon a bed of well rammed clay 0.30 meter thick, spread upon the slope to prevent the sand from being washed away. This pitching was 0.50 meter thick and set in Portland cement. A curved form decreasing in declivity was given to the new sea front of the dike to better protect it against the action of the waves. The engineers, seeing the great difficulty of driving piles through the sand, had recourse to the method of sinking them by means of water jets. Before using the water jets, to drive a panel of sheet piling 2.50 meters high and 180 long required 900 blows from a ram weigh- ing 600 kilograms, and occupied from 3| to 144 hours, or an average of 84 hours. The resistance of the sand was such that the thickness of the piling had to be increased from 0.08 to 0.12 meter, and even then the wood was frequently broken. The first trials of the jets gave such remarkable results that the method was subsequently employed to sink most of the foundation walls of the quays. The water jet was forced into the sand by means of a hand pump through an iron nozzle 0.027 meter in diameter, connected to an India-rubber hose (see Plate V). This so facilitated the work that a panel of seven or eight planks was sunk in one hour and nine min- utes, and in many cases the time was reduced to fifteen minutes. The number of blows did not exceed fifty, and were only necessary to overcome the friction between adjacent panels, which were tongued and grooved to make a tight joint. The weight of the ram on a single pile 3 meters long was sufficient to sink it immediately, and the former thickness of 0.08 meter for the panels was restored. This dike was finished without accident, but, several years later. CIVIL ENGINEERING, ETC. 675 during the high tide of an equinoctial storm a great breach was made in it; this was closed and the profile of the dike modified as shown in Fig. 109. The height and thickness are the same as before, but the top had a slope of one-tenth from the edge of the stone pitching, for 10 meters back from this crest, with a stone flagging prolonged by a belt of puddled clay from 0.25 to 0.30 meter thick. 676 UNIVERSAL EXPOSITION OF 1889 AT PARIS. At 30 meters from the edge a turf banquette 1.50 meters high formed the last barrier to the water. Finally a masonry berme 10 meters wide was constructed at the foot of the dike, following the declivity of the beach. Thus reconstructed, the dike has resisted the most violent storms. (180) Dredging of the channel. — The work of deepening the outer channel was carried on at first by a Dutch company, and then by the Fives-Lille Company. The quantity extracted at the end of 1888 by both companies was 1.472,933 cubic meters, and the price last paid was 0.92 francs per cubic meter, raised and carried 1 mile. A careful study of the plan of the soundings made from month to month Fiq. 110.— Cross section of the wall of the northeast quay of the outer harbor. during the last seven years shows that, by dredging out annually 170,000 cubic meters, the outer and inner channels may be maintained at a depth of 4 meters below datum; this, at the price of 0.92 francs per cubic meter, amounts to 85,000 francs. (181) The sluicing lock, which serves to discharge the water accu- mulated in a basin of 90 hectares area, has five openings, each 0 me- ters wide, separated by piers 3.50 meters thick. The wetted peri- meter of these openings has been arranged so that a discharge of 1,000,000 cubic meters can take place in an hour under a head vary- ing from 0 to 4T meters. CIVIL ENGINEERING, ETC. 677 (182) Outer harbor quays. — The northeast quay, 570 meters long, shown in section by N Fig. 109, is for the Calais and Dover mail steamers. The station and lines of the Northern Railroad Company are placed here. • The quay wall is nearly vertical and flush, except that at equal distances along it there have been made four recesses 55 meters long and from 8 to 9 meters deep. In .these recesses the iron landing stages are arranged in three stories, for the landing and embarkation of passengers and freight. The two central recesses, which are opposite the railroad station, are 120 meters long; the others 100; the rest of the quay may be used for a fifth steamer, or for the dredges and tugs belonging to the port. The plane portion of the wall between each recess has a uniform section of 7 meters thick at the base and 2.70 meters at the top. The foundations are sunk to the reference — G.25 meters, that is, 2.75 meters below the bottom of the outer harbor, and the total height is 15.75 meters. Near the base the face of the wall is vertical ; above it has a batter of one-tenth. The thickness of the vertical portion is 7 meters, but above it is reduced by steps as shown in Fig. 1 10. At the right of the landing stage the total thickness of the wall is 13.75 meters for a length of 04 meters: in this wall two recesses are made, each 22.50 meters long and separated by a wall 10 meters thick. The bottom of each recess slopes slightly to keep it clear of water. The depth of the lower is 8.95 meters, and that of the upper 8.20 meters. The quay is formed of two parallel walls; the outer, an extension of that of the quay and 4 meters thick, comes up to the level, 2.25 meters; the other, 4.50 meters thick, extends to the top of the quay; the two walls are connected by an archway par- allel to the quay. The second wall, hollowed out behind by little arches, contains a staircase between the middle and upper landings. Each landing stage is formed of six frames perpendicular to the face of the wall, which, with the lateral walls, carry the floor beams of the middle and upper landings. Each frame consists of three uprights, one inclined and the other two vertical ; the bases of the two latter rest upon iron plates imbedded in the masonry; the columns are stiffened by cross braces. These columns support the middle deck, and the upper deck is supported in a similar manner, as shown in Fig. 109-N. (183) The southwest quay (S, Fig. 109) is reserved for the use of the ocean steamers calling at Calais. It has a depth of 7 meters below low tide ; the foundations were sunk to a reference — 10 meters ; its coping is +9 meters, and its total height 19 meters. This founda- tion was accomplished in a special manner, which will now be ex- plained. (184) Foundation of the northeast and southwest quays of the order harbor. — The width of the foundation was 7 meters ; to make a i C78 UNIVERSAL EXPOSITION OF 1889 AT PARIS. trench 7 meters wide and 5 meters deep in the fine sand and lay the quay walls inside required the construction of a costly cofferdam, and even then the results were not absolutely sure. The method by compressed air was' equally expensive but surer. After some very successful experiments it was decided to apply, for sinking the masonry curbs 7 meters by 6.50 and 5 meters high, the process so successfully used in driving the wooden piles at Calais. These curbs were placed side by side. The exterior walls are vertical, the interior walls are vertical for a distance of 6.50 meter. They are 1 meter thick, and are shown in Figs. Ill to 113. The base is of concrete made in a mold, which is taken off when the con- crete is set ; the rest is built up of masonry laid in cement. The blocks thus formed (PI. VI) are not sunk until ten days after they are finished. This operation consists in exposing the sand beneath the block to the action of powerful water jets, thus throwing a mixture of water and sand from without into the cavity within, and pumping the mixture of sand and water thus obtained in the middle of the curb. For this purpose a centrifugal pump, driven by a portable engine of 10-horse power, was em- ployed; the suction pipe was suspended from high scaffolding, the orifice being placed a little below the level of the bottom of the block. Four direct- acting force pumps were used to drive the water into the sand, each pump throwing 600 liters per minute, with a pressure of 2 kilograms, through three nozzles connected to the pump by India rubber hose, which passed over a light, portable staging above the curb. The whole plant was mounted on four platform cars and ran upon rails laid parallel to the face of the quay. Plate VI shows the general arrangement, and Fig. 1 II shows the ar- rangement of the twelve jets. Eight of them were arranged around the sides of the octagonal opening, and the four others around the suction pipe of the centrifugal pump. Three of these played around the mouth of the suction pipe diluting the sand, augmenting the efficiency and diminishing the danger of choking. The twelfth pipe was united to the suction pipe, into which it discharged just above Fig. 114. — Arrangement of the jets. Paris Exposition of 1889 — Vol. 3. CONSRTUCTION OF THE OUTER HARBOR QUAYS AT CALAIS. PROCESS OF ■IKING THE MASONRY FOUNDATION CURBS BY MEANS OF JETS OF WATER. 9 CIVIL ENGINEERING, ETC. 07 !) its lower extremity. This arrangement, devised by Mr. Delanoy, kept the pump clear. The jets from the nozzles, all working simul- taneously, mixed the sand and water together, and this mixture was drawn out by the centrifugal pump. Care was taken during the op- eration that the quantity of water forced in should be the same as that pumped out, so that the level of the water in the curb should bo just below the ordinary level of the water in the surrounding sand. In this way there was no danger of the sand on the outside caving in, and only a quantity of sand not much greater in bulk than that of the curb was taken out. As one of these blocks sank, two spirit levels were placed upon the top, by which it was easy to see whether it was sinking vertically, and if it was not, it was regulated simply by lowering or raising nozzles on one side or the other so as to force it more or less into the sand. When the curb had reached the bottom, after a descent of 4 or b meters, the sand was allowed to settle and the opening was tilled with hydraulic bdton. This layer when hardened formed a tight tamp, which resisted the under pressure of the water ; the empty space was then pumped out and filled with bdton cement up to the level, where it could be tilled with masonry. Fig. 116. — Method of cementing two con- secutive blocks together. The method adopted for the whole work was as follows: A general plan was prepared indicating the dimensions and position of each curb, with a space of 0.40 meter between each, which is to be tilled afterwards. The positions of the curbs were then marked out on the ground. Experiments had shown that in sinking such a row of foundations, if every alternate curb was sunk, the condition of the intermediate ground was unaffected. The work was begun by sinking all the curbs numbered 1, 3, 5, etc., and then those numbered 2, 4, 0, etc., until all were sunk. The curbs wei’e none of them filled until all were in place, in order to avoid any trouble which might arise from the displacement of the sand under the foundations. When all the curbs were sunk they were filled and then these consecutive blocks were cemented together, as follows: On the front and back of the blocks iron plates (Fig. 116) were sunk down to the foundations by means of water jets. These plates closed the space between two 680 UNIVERSAL EXPOSITION OF 1889 AT PARIS. consecutive blocks, the sand between the blocks was then cleared out by the nozzles and pump, and the space filled with beton, made of hydraulic mortar. Upon the blocks thus united together the foundation of the wall was built in masonry laid in Portland cement. PI. VI shows this whole operation. The facility with which these blocks were sunk permitted the en- gineers in charge to augment the dimensions of the blocks for the foundation of the southwest quay, as well as the depth to which they were sunk. They were 8 meters square and 8.75 meters high, and weighed 800 tons. These blocks were sunk with the same accuracy as those of smaller dimensions for the northeast quay, but some diffi- culty was experienced in cementing the blocks together, on account of the water forcing its way under the iron plates. The time of sink- ing the small blocks of the northeast quay to a depth of about 4.50 meters varied from ten to thirty-five hours, the mean time was re- duced to about twenty-three hours, and the mean volume displaced per hour was 6.35 cubic meters. The time of sinking the larger blocks, 8 by 8 by 8, varied from 22 to 119 hours, with a mean of 45. The sinking of the still smaller blocks, 4 by 4 by 4.45 meters, was relatively easier, the mean volume displaced per hour being 12.5 cubic meters. The total length of the quay walls of the outer harbor, constructed under the shelter of the dikes between 1884 and 1888, is 770 meters. The corresponding expense in round numbers was 2,750,000 francs, including the plant. The expense of sinking the curbs was 99,000 francs. This expense corresponds to a total volume displaced of 31,253 cubic meters, which makes the cost 3.17 per cubic meter of sand extracted and masonry put in its place. The cost of removing the sand between the sunken blocks and replacing it with beton was 27,540 francs, thus bringing up the total cost of sinking the solid walls to 3.84 francs per cubic meter, including the labor and the cost of the plant. (185) Eastern dock locks . — The communication between the outer harbor and the eastern dock is established by two parallel locks of the same length but unequal widths. The larger has a clear width of 21 meters. The level of the lowest part of the invert is 1.75 meters below the zero of the charts. Gate chambers are formed in the ma- sonry to receive one pair of gates at one end of the lock, two pairs at the other, and one between. The maximum length of the lock chamber is 133.51 meters. This length can be divided in two parts, which are, respectively, 57.50 meters and 76 meters, by means of the intermediate gates. The smaller lock is similar, and has a width of 14 meters. On the left side of these locks two arched longitudi- nal culverts are made; one, 2.10 meters wide and 3.60 meters high, G81 CIVIL ENGINEERING, ETC. • forms the prolongation of the culvert of the western quay upon the dock, and is intended to carry off the flood water from the Calais canal, the water from the dry dock, and that from the boat locks. (18G) Culverts for filling and emptying are also placed in the cen- tral pier and in the chamber wall on the right side of the smaller lock. The first is 2.20 meters wide, the second 1.60 meters wide, and the height, 3 meters, is the same in both. Communication is made between these outlets and the locks by transverse branches, and the flow of the water regulated by valves and sluices. (186) Lock gates . — Each leaf is 12.25 meters wide, 9.80 meters high, and 1.10 meters thick for the flood and 1.30 for the ebb gates. The iron frame consists of'eight horizontal girders, spaced from 1.34 to 1.36 meters, connected at the ends with two uprights, and having four intermediate standards 2.32 meters apart. The leaves rest on pivots at the bottom, and at the top they are held by iron trunnions passing through collars anchored in the masonry. The 14-meter lock is furnished with gates similar in all respects to those just described. The total weight of each leaf is 85 tons for the larger and 5(H for the smaller lock. (187) Turning bridges . — Four turning bridges are constructed across these locks to provide for the public traffic, two at the lower end and two at the upper. They are of similar construction, and differ only in length, 47.13 and 35.80 meters. Each bridge has an iron superstructure and a double wooden flooring. It consists of a single span turning on a pivot set in the lock wall. The framework of each bridge consists of two main girders resting on the ends of a box girder, and united by cross-ties, which are themselves connected under the flooring by stringers. The foot path is carried on brackets mounted on the outside of the main girders, which have the form of a parabola above and below. The height of each girder is 3.30 meters at the right of the box girder and 2.70 meters at the ends. When one of the bridges is in use it rests upon the center pivot, and also on three locking brackets, one at the end of the span, another near the pivot, and a third at the breach, or tail end. When the bridge is opened the locking brackets are withdrawn and the superstructure rests principally upon the pivot and partially on the breach rollers. During the rotation the rollers bear a maxi- mum load of 5 tons and roll on a cast-iron track. The total weight of the superstructure of one large bridge is 265 tons, including counterpoise of 45 tons placed in the breach, used to tilt the bridge, so as to set free the supports. The weight of one of the smaller bridges is 190 tons, including the counterpoise of 30 tons. 682 UNIVERSAL EXPOSITION OF 1889 AT PARIS. 188. Apparatus for handling . — The sluices, gates, bridges, cap- stans, etc., are moved by hydraulic power distributed from a central station erected near the lock. The green heart wood sluices slide in grooves cut in the granite facing of the polished walls. The lock gates are opened and closed by hydraulic presses and tackle; two presses for each leaf placed side by side, one for opening and the other for closing the gates. The opening and closing chains pass over two pulleys, one above the other, in the wall near the heel post. They pass over a series of guide pulleys attached to the upper part of the leaf, and are secured to a ring bolt in the wall. The controlling valve, worked by a hand lever, is so arranged as to make a communication between one of the cylinders with the pressure main and the other cylinder with the exhaust main. The arrangement of the admission and exhaust ports is such that it is possible to vary at will the relation between the tension on the chain in operation, and the resistance offered by the one which corresponds to the reverse movement. A small auxiliary press, placed at the end of the closing cylinder, forces the closing piston to the end of its stroke during the process of opening the gates, so as to facilitate the unrolling of the slack of the chain bet ween the walls. By this novel arrangement the opening and closing of the gates can be effected by one operator, who can always hold the leaf in either direction against the force of the waves. (180) The machinery for working the turning bridges moves the pivot, arranged so as to tip and rotate independently, the tilting and locking presses, and the two rotating tackle presses. The pivot turns in a cast-iron cylinder, filled with glycerine main- tained at a pressure of 50 kilograms per square centimeter, upon a circular lubricated surface ; it carries at its upper part the cylindrical rolling joint which serves for the tilting. The tilting presses act by vertical plungers placed under the principal girders of the breech. When the bridge is raised by the tilting presses the locking presses throw on or off the breech brackets which support the bridge when it is in use. The chains are coiled around an iron drum placed under the super- structure on a level with the supporting box -girder. Four 1-ton capstans are placed along each of the outer sides of the lock ; three others of 5 tons, and two of 1 ton, are arranged on the central wall between the two locks for hauling the vessels. These capstans are driven by small three-cylinder hydraulic engines so ar- ranged that they can be worked by hand if the water gives out. They are so placed that they can be utilized for opening the gates or turning the bridges in case the accumulator gives out, and in such a case a hand pump specially constructed serves to work the sluices and the tilting presses. CIVIJ. ENGINEERING, ETC 688 The central hydraulic machinery which supplies the water under pressure, for working the presses which have been described, is contained in a building situated to the north of the locks. It consists of two groups of pumps, each driven by a 50 horse-power engine, and two accumulators of 730 liters capacity each. The machinery is sufficiently powerful to supply the Chamber of Commerce with water under pressure, and to drive other hydraulic machinery situated on the quays. The applications of hydraulic power above described are due to M. Barret, engineer of the Marseilles docks, who prepared the plans, which were carried out by the Fives-Lille Company under the direc- tion of the engineers of the port. (190) The quay walls of the eastern dock have a total length of 1,505 meters. These walls rest on abdton foundation 2 meters thick, carried down to a depth of —3.75 meters. The normal profile of the walls has a height above the foundation of 10.25 meters and a thick- ness of 5.80 meters at the base and 2.50 meters at the top. This dif- ference in thickness is obtained on the outside by a batter of one to ten, followed by a curved face of 8 meters radius, and on the land side by a series of steps 0.37 meter wide; (See Fig. 117). In the smaller basin beyond, where the height of the wall is only 7.75 me- ters, the thickness is reduced to 4.20 meters at the base and 2 at the 1 1 1 1 1 • O I 9 3 4 5 \f 9 5 4 5 M Fig. 117.— Profile of the wall of the eastern dock. UNIVERSAL EXPOSITION OF 1889 AT PARIS. 684 top. Those profiles are modified for the western quay, on account of a culvert 2.10 meters wide and 3.60 meters high, placed at the back and used for carrying off the flood waters of the Calais Canal into the outer harbor, as well as the water from the dry dock and the boat locks. (191) Foundations. — The width of the foundation upon which the walls rest is 6.30 meters. It consists of a mass of bdton sunk to a depth of 2 meters within a coffer dam formed of piles and sheet pil- ing. The dimensions of the piles were 0.30 by 0.25 by 4.50 meters in length; the planks forming the sheet piling were 0.10 meter thick. The estimated cost of these coffer dams was 450,000 francs. The application of the water jet process enabled these dams to be con- structed not only in very much less time than had been estimated, but reduced the cost to 160,000 francs, thus realizing an economy of 290,000 francs. This economy resulted not only from the diminished cost of sink- ing the piles and sheet piling, but by allowing the use of smaller piles and thinner planks. PI. V shows the operation of sinking the piles. The total cost of constructing the quay walls of the dock and the innet basin was 4,000,000 francs. (192) The western quay is specially reserved for handling and storing valuable merchandise which has to be protected against the weather, and which is only allowed to remain a very short time. It is provided with railways and sheds. The normal width of the quay is 100 meters, divided as follows: First. An open zone 11.50 meters wide extending the whole length of the quay, carrying a track for hydraulic traveling cranes, and two other tracks for freight traffic. Second. A zone of 48 meters wide, including a great central hall 40 meters wide formed by two parallel roofs each 20 meters wide, and two exterior awnings each 4 meters wide. Third. A collection of five tracks, one placed under the awning next to the dock, the remaining four occupying an uncovered space 18 meters wide. The track standing nearest the sheds is used chiefly as standing room for wagons to be loaded or unloaded. The four others serve as sidings for full or empty cars and the mak- ing up and dispatching of trains. Fourth. A paved road 16.50 meters wide, including space for a track which will subsequently be laid along the outer sidewalk. Fifth. A sidewalk 6 meters wide running along a series of blocks for a depth of 50 meters along the quay, to be reserved for the construction of stores, depots, and other establishments required for a marine station. CIVIL ENGINEERING, ETC. 685 Beyond the quay proper the public domain extends along a zone 70 meters wide, including the belt of 50 meters occupied by the blocks reserved, just referred to, and by an outer street 20 meters wide, upon which railway tracks will be laid to accommodate the stores when they are constructed. (195) The eastern quay is reserved for the storage of a low class of merchandise, such as wood, iron, minerals, charcoal, etc., which can remain exposed to the weather without damage. The total width of this quay is 140 meters, divided as follows: First. Three lines for loading and unloading cars. The middle line is reserved for a traveling crane. Second. An open space G7.50 meters wide. Third. Five tracks occupying a total width of 21 meters. Fourth. A macadamized road 13 meters wide. Fifth. A zone of 10 meters fenced in and occupied by two branch lines connecting the central Calais station with the maratime term- inus. Sixth. An outer street 15 meters wide. (194) Hydraulic cranes . — A system of mains has been laid down, starting from the central hydraulic station and extending around the dock, to supply the various cranes, etc., established on the quay. These include 10 traveling cranes of 1,500 kilograms each, 2 double- power traveling cranes of 5,000 and 2,500 kilograms, and G movable winches of 750 kilograms, 1 fixed double-power crane of 20,000 and and 40,000 kilograms. (195) Hie dry dock is constructed at the southern extremity of the eastern dock, and a space has been reserved alongside for the con- struction of two similar docks when they shall be required. An unloading stage for timber occupies provisionally the space reserved for these two docks. This work comprises three different parts — the entrance lock, the dock itself, and the culverts. The entrance lock is 21 meters wide, like the great lock of the eastern dock. Its side walls have two recesses for the reception of the caisson gate which closes the entrance. The dry dock has a total length of 141.25 meters measured along the flooring from the inner recess of the caisson gate to the base of the rounded edge. The maximum thickness of this gate being 4 meters, the useful length of the dock is 138.50 or 152 meters, ac- cording as the gate takes its bearing against the inner or the outer recess. The width of the flooring between the bottom altars is 9.30 meters, including the side draining channels which run round the floor of the dock. The first four altars starting from the bottom are 0.35 meter high and 1.30 meters wide. The width of the dock at the level of the fourth altar is thus 19.70 meters; a width requisite for the accom- modation of the light-draft paddle steamers used for the channel UNIVERSAL EXPOSITION OF 1889 AT PARIS. <(‘>86 service. From this level to that of the coping the dock has two in- termediate steps 1.25 meters wide, to serve for shoring, and to facili- tate the passage of the workmen. The width at the coping is 27.40 meters. Several stairways are placed along the walls, and a timber slide is provided at the extremity of the rounded end. A culvert 1.25 meters wide and 2.50 meters high, opening into the lower end of the dock near the inner recess of the caisson gate, is built behind each wall, and small transverse culverts run from it to the lateral channels on each side of the flooring. The culverts carry off the water to the pumping well when the dock is emptied or drained. The well under the engines and centrifugal pumps is arranged so as to serve in future for the filling and draining of the two other docks not yet built. The engines and the pumps are calculated to pump out the dock in 3 hours at the most. A set of small centrifugal pumps serve to keep the dock clear while in use. The great pumps are driven by belting from two upright engines which together develop 800 horse power. The cost of constructing the dock amounts in round numbers to 2,700,000 francs (196) The barge dock forms the prolongation and end of the Calais Canal, and communicates on the eastern side with the eastern dock and on the west with the old port. The flooring is placed at the ref- erence 1.95 meters, that is to say, 2.80 meters below the normal level of the canal (4.75 meters). The boats never draw more than 1.80 meters. The quay walls of this dock are of solid masonry, set in hydraulic cement upon a bed of bdton 0.70 meter thick. The height of the wall is 4.45 meters; its thickness varies from 2 meters at the base to 1.10 meters at the top, with a batter of one-fifth or one-sixth. Two locks connect the eastern branch of this dock with the new eastern dock; they are 38.50 meters long and 6 wide, separated by a wall 7 meters thick. The gates are of oak and worked directly by hydraulic pressure. (197) The guard lock is built at the lower end of the western branch of the boat basin, and is arranged so as to form a dam either against the sea or against the canal. Its gates must not only be able to resist the pressure of the water in both directions, but they should also be capable of being opened and closed against the stream, whatever may be the direction or the velocity of the current. The length of the lock is 26 meters, and its clear width 7; it is closed by two pairs of miter gates, each of which consists of two vertical wings of unequal width united to the same heelpost. When these are closed they form an angle slightly less than a right angle; when the lock is open each wing comes into its appropriate curved recess — in plan the quadrant * CIVIL ENGINEERING, ETC. 687 of a circle — formed in the side wall of the lock, and corresponding in shape to that of the gate. The lock is closed when the narrower wings of the gates are brought together against the miter sill. In opening and closing, the second wing of each leaf remains within the curved recess, in which it moves with a slight play between itself and the curved wall. On each side of the lock are two separate culverts, starting from the lock head and tail and emptying into the curved recesses above referred to. These culverts can be opened or closed at will by a system of sluices, in such a manner that the pressure of the water discharged from them can be exerted against the exterior face of the wider wing of the leaf, at the head or tail end, whenever there is a differ- ence of level at the two ends of the lock. If the culvert communi- cating with the lower end is closed, the gates will shut themselves if the direction of the fall is from the upper to the lower end. If this state of things is reversed, the sluice controlling the upper end of the culvert must be closed and that at the lower end opened. Five bridges have been constructed over the Calais Canal and barge dock to maintain the railroad and boat communications. (198) Cost . — The cost of the boat basin was as follows : Francs. Earthwork and masonry 3, 800, 000 Lock gates and apparatus 290, 000 Bridges 310,000 4, 400, 000 The designs of the works above described were prepared under the direction of MM. Stoecklin. Plocq, and Guillain, chief engineers, and M. Vdtillart, engineer of the port of Calais. I wish to acknowledge my special obligations to M. Vdtillart for descriptions and photographs. Chapter XIX. — The new outer harbor at Boulogne. (199) The situation of the port of Boulogne in 1878, when it was decided to make a deep harbor here, was as follows : A bar was formed near the entrance to the jetties, rising to a height of 1 meter above the zero of the charts. The entrance to the interior channel, between two jetties 70 meters apart, exposed to all the winds from the west, was inaccessible at high tide for ships draw- ing more than 5 meters. The bottom of the inner harbor, with a surface of 13 hectares, was 3 meters above zero. The dock, accessible through a lock 21 by 100 meters, and having a surface of G.87 hectares, had its bottom 0.60 meter above zero. 688 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The difficulties of access and the insufficient depth in the channel prevented this dock from doing its full service. Notwitstanding all these difficulties the annual tonnage exceeded 983,000 tons, the number of passengers was 130,000, and the duties collected exceeded 7,500,000 francs. (200) Project for a deep-water harbor . — There was a littoral cur- rent of 3 knots per hour in front of the port between the two rocky points of Heurt and Creche, where the sand was always washed away but no shoal made. If, therefore, a breakwater 8 or 9 meters deep be erected from north to south, through shoals parallel to the direction of the current, and in a line with these two points, it will be exposed to erosion rather than to silting. If this breakwater be connected with the coast at its two extremities, and a principal en- trance reserved toward the west, this pass will preserve its depth and no serious disturbance will be made in the regime of the coast. Fig. 118 .— Plan of the port of Boulogne : a, the southwest dike ; b , the (like parallel to the coast ; c, the isolated mole ; d, the northeast dike. The Liane River Hows through, m, the storage basin, s. the inner basin, r, the inner harbor, then out through the jetties S. The port thus formed will be in no danger of silting up. The proj- ect of M. Stoecklin, prepared according to the above principles, is represented in Fig. 118. It consisted in making, in front and to the south of Boulogne, a new harbor nearly rectangular in shape, with an area of 300 hectares, hav- ing two passes open to a depth of 8 meters at low tide; in the interior, landings and quays are built, accessible at all times for steamers drawing 5 meters of water. (201) The perimeter of this harbor is formed of three dikes, one parallel, and the others nearly at right angles to the shore. The first has a total length of 1,100 meters divided into two portions by an intermediate pass, called the western pass, 250 meters wide. The north branch, c, comprised between the west pass and the north pass CIVIL ENGINEERING, ETC. 689 which separates it from the northeast jetty, d, is to form a mole 500 meters long, and separated from the land. The southern branch, b, 600 meters long, unites with the southwestern dike a by a curve of 350 meters radius. This last dike is nearly perpendicular to the shore, where it is united with the rocks. It is 1,650 meters long, in- cluding the curved portion. The northeast dike, d, whicli completes the inclosure, is the pro- longation for 1,440 meters of the actual northeast jetty. Its north- west extremity is separated from the isolated mole by the north pass, 150 meters wide.' (202) The object of the proposed improvements was as follows: First. To furnish a harbor of refuge for the fishermen and coasters. Second. To facilitate the access to the inner harbor by protecting the entrance into the channel against the waves at all times, and pro- viding approaching vessels with a shelter where they could await in security a favorable time and tide. Third. To provide quays accessible at all times for channel steam- ers as well as for coasters and fishing vessels. (203) Work done from 1879 to 1889. — The work began in July, 1879. At the foot of the abrupt cliffs bordering on the sea between Boulogne and Portel they built two wharves, having a surface of 7 hectares included between two retaining walls, and these wharves were connected by a road with the city, and by a railroad with the northern railroad station. Quarries were opened at the foot of Portel cliffs and united with the wharves by inclined planes. They then constructed a little haven, included between the shore end of the southwest dike and two jetties 100 meters and 270 meters long, to facilitate the loading of the materials intended to form the sub- structure of the proposed dikes. It was only after these first works were finished that they could proceed with the construction of the dikes. The part of the inclosure of the deep-water harbor already finished includes the branches a and b. These two branches consti- tute in reality one and the same jetty, a beginning perpendicular to the coast, b parallel with it, and the two united by the arc of a circle of 350 meters radius. (Fig. 119). This jetty, which forms a breakwater in the direction of the south- west and west, begins at a point on the coast between Boulogne and Portel, at 1,750 meters to the south of the actual entrance to the har- bor. Its total length is 2,110 meters, including 1,265 meters for the dike a from its beginning, 360 meters for the curve, and 485 meters for b. The profile of the dike consists of two distinct parts corresponding to the substructure and the superstructure. The substructure is formed by a mass of natural and artificial riprap, composed of a central core of stones weighing 100 kilograms apiece, resting on the bottom and rising to a level of 1 meter above low tide. The slopes of H. Ex. 410— vol in 44 C90 UNIVERSAL EXPOSITION OF 1889 AT PARIS. CIVIL ENGINEERING, ETC 691 this first mound are covered on the shore side, for a thickness of 2.50 meters, by what is designated as “rubble of the first category.” It is a stone pitching made up of rocks weighing 500 kilograms each. On the side toward the sea the slope is protected, first, by a revet- ment of rubble work, made up of rocks weighing 6,000 kilograms apiece, called “rubble of the second category,” and, second, by bdton blocks of uniform dimensions weighing 33 tons each. (Fig. 120). Between the references +2 and +4 meters rises amass of masonry 9 meters wide, serving as the foundation of the masonry wall which constitutes the superstructure of the dike. The profile of this wall is trapezoidal, 6.90 meters high, 7.66 me- ters wide at the base, and 6 at the top. The upper platform rises to the reference 10.90 meters, that is, 2 meters above mean high water. It is surmounted by a parapet 1.40 meters high and from 2.50 to 2 meters thick. On each side of the wall and on a level with the lower platform the slopes are consolida- ted by masonry bermes formed of isolated blocks, each 6 meters long, which serve to protect the foot of the wall and also afford a path for the workmen and materials at low tide. The thickness indicated for the wall was adopted at a distance of 1,350 meters from the beginning of the dike. The width at the top is only 4 meters for a distance of 1,120 meters from the shore ; then it is made 5 meters for a distance of 1,350. All along the curve which forms the part of the dike most severely exposed to southwest winds and storms the width is 6 meters ; the outer slopes have been loaded with several layers of artificial blocks, and the exterior bermes raised to the reference of 5 meters. A slope communicates between the upper platform of the dike and the interior berme, to facilitate the supply of materials during the con- struction, and increase the time of the work for each low tide. The dike is terminated by a provisional pier-head signal, and by a lu- minous buoy. The field work included a double organization corre- 692 UNIVERSAL EXPOSITION OF 1889 AT PARIS. sponding to liigli and low tides. The sinking of the artificial blocks and the rocks for the revetment took place at high tide. The latter were transported and sunk by means of hopper barges towed by a little steamer ; each of these barges carried a weight of 100 tons. The artificial blocks were unloaded at high tide by means of a special wrought-iron barge having three vertical pits, with which at each trip of the barge they could sink three blocks, but this operation required a certain precision, and generally only one trip could be made at each high tide. The loading and discharge of the riprap was possible, on the con- trary, with waves 0.50 meter high, which allowed the use of more than half of the tide. At low tide the stones required to complete and even up the central core were sunk, as well as a great portion of the natural and artificial blocks which were to form the revetment of the side slopes. For the heavy rock work they made use of tip wagons ; for the great blocks they employed tlnee-wheeled trucks, the platform of which could be raised and tipped by means of jacks. These trucks ran upon rails laid on the bermes of the walls already constructed. They were able to utilize, at low tide, four-fifths of the number of tides; during the winter they could only succeed in preventing the dispersion of the interior mass by the action of the waves. The advancement was difficult at first, and to avoid the loss of material they were obliged to stop the riprap. work from November to April. Experience showed that the only way to prevent accidents, and to extend and preserve the advancement attained during the good sea- son, was to construct, as soon as the platform emerged to a sufficient height, isolated blocks of masonry which loaded and consolidated this platform. These blocks were to make a part of the bermes and the foundation of the walls, but they rested sometimes as isolated blocks, and could settle until they had attained a state of stable equi- librium. At the end of about a year the blocks situated in the cen- tral part of the dike were united so as to form the foundations of the wall. At the moment of stopping work all the joints exposed to the waves were filled with rapid-setting cement. When the work recom- menced this mortar was removed, the joints were cleaned, and new cement was placed on all the parts against which new masonry rested. The total cost, from 1879 to 1889, of the organization of the works and the construction of the southwest and parallel dikes (a and b), amounts in round numbers to 14,500,000 francs. Besides, 1,850,000 were expended in constructing the first part of the wharf, and 2,000,000 were used up in dredging in the interior harbor and the entering pass. (204) Results obtained — Improvements to be made . — Although the programme of 1878 has not yet been completed the following re- sults may be considered as already obtained. CIVIL ENGINEERING, ETC. 693 First. The entrance to the interior channel is completely sheltered against the southwest winds and tempests, which are the most fre- quent and violent in this region ; it is even partially sheltered against the tempests and winds from the west. Second. The regime of the currents at the entrance of the port has been completely modified. The current of flow passed formerly at the head of the jetties, at the moment of high tide, with such velocity during certain tides as to render the entry of the port impossible for great ships ; it is carried to-day beyond the dike and is only felt at the entry of the port as a feeble eddy. Third. The protection obtained at the entrance of the port against the waves and currents, has permitted the deepening of the exterior pass and the channel, and the maintenance without difficulty of the depths already obtained. These depths are to-day more than 4 meters below zero in the exterior pass, and 2 meters between the jetties. They are sufficient to allow the regular service of steamers between Boulogne and Folkestone, a service organized more than three years ago. Fourth. The dike already forms a little haven of 50 acres suffi- ciently sheltered from the southwest and west winds, which will be of great service as soon as the dredging giving it a depth of 6 or 7 meters shall be finshed. With regard to the modifications of the beaches, it may be stated that the anticipations of the authors of the project are realized. There is a tendency to erosion at the bottom, in front of the paral- lel dike, indicating that the depth in the passes of the harbor will be kept in order naturally if the primitive project is entirely realized. The beach situated on the south of the southwest branch has risen notably in its upper parts, the slope has become more steep, but its foot does not appear to have changed, and the great current which follows the lateral branch will not permit it to advance. On the interior of the harbor, that is to say, on the north of the dike, there is a little silting, produced on account of the calm obtained, but, as has been foreseen, this silting is of no importance and can easily be removed by dredging. These excellent results have allowed the completion of the pro- gramme of 1878 to be adjourned without prejudice to local interests. The conditions of access to the port of Boulogne are such to-day that the quays and wharves projected for the deep-water harbor, always accessible to the steamers and fishermen, may be carried to the inner harbor. The deepening of the harbor and the construction of the new qiiavs will be immediately carried out. (205) As to the construction of the dikes, it is possible that when the work is recommenced the engineers will consider them useless for the security of the harbor, the complete closing of which had been originally planned ; a simple prolongation of the actual parallel 694 UNIVERSAL EXPOSITION OF 1889 AT PARIS. dike for a length of 500 or 600 meters will probably be sufficient to assure an excellent shelter against great storms. But the works must be completed by important dredging, to assure, over a sufficient extent, the depth of 8 meters requisite for ship navigation. The project for the deep-water harbor at Boulogne was drawn up by M. Stoecklin, general inspector. The works were carried out successively under the direction of MM. Plocq, Cfuillain, and Vdtil- lart, chief engineers, and Barreau and Mommerque, assistant engi- neers. Chapter XX. — Port of Havre — Bellot Lock. (206) Bellot lock . — The Bellot basin for the use of the transatlantic steamers connects with the Eure basin by a lock 30 meters wide. The lock is furnished with ebb gates separating the two basins. It is crossed by a drawbridge of a single span and double track. Hy- draulic capstans placed on each wing wall are designed to facilitate hauling the ships. All the working apparatus is moved by hy- Fig. 121. Transverse section of the Bellot lock. draulic power. The chamber walls of the lock are vertical, and unite with the invert by circular arcs of 2 meters radius ; their thickness is 7.70 meters, and the sill is placed at the reference —2.65 meters, which gives a draught of 8.30 meters at low tide. (207) Iron drawbridge . — The iron bridge just mentioned is 53.25 meters long — 36 meters for the span, 17.25 meters for the breech, and 7.72 meters wide. It consists of two girders forming the parapets, with a variable height from the extremity to the point where the tension is a maximum. These girders are united by cross girders and wind ties. The longitudinal girders have a height of 2. 10 meters at their extremities, and 4 meters at the right of the pivot. They are formed of a trellis of channel iron inclined at 45 degrees and spaced 0.85 meter between the axes. The uprights divide the girder into fourteen panels 3.40 meters wide. The plate-iron transverse beams are 80 centimeters high and 3.40 meters apart; they rest on the lower plate of the side girders, and are united by stringers placed CIVIL ENGINEERING, ETC. 695 under the rails of the railroad and under the plates of the roadway. The bridge is calculated to allow the passage on the railroad of the heaviest locomotives of the Western Company (14 tons per axle), or the simultaneous passage upon each of the roadways of two files of carts weighing 11 tons per axle. 696 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (208) Lock gates . — The lock gates (see Plate VII) are of plate iron, each leaf 1G.515 meters wide and 10.90 meters high. These gates retain the water in the Bellot basin at the reference ?.85 meters, that is to say, at 10.50 meters above the level of the invert. They are calculated on the hypothesis that the level of the water in the Eure basin may by some accident fall to the zero of the charts. The sys- Paris Exposition of 1889— Vol. 3. Civil Engineering, etc.— PLATE VII. HAVRE. LOCK GATES OF THE BELLOT BASIN CIVIL ENGINEERING, ETC. 697 tem of construction adopted consists of verticals supporting the ex- terior skin and resting on two horizontal crossbeams, one on the upper part and the other on the lower. The skeleton consists of: First. A frame made by an upper cross girder, a lower cross girder, and two tubular pits forming the heel and miter posts. Second. Nine vertical ribs spaced 1.393 meters apart. Third. Two horizontal intermediate girders to brace the uprights. Fourth. Horizontal U-shaped plates unequally spaced and serving to stiffen the skin which forms the two faces of the gate. The space included between the lower horizontal girder and the first intermediate, counting from below, constitutes a series of water- tight chambers intended to ballast the leaf; the rest of the space included between the lower horizontal girder and the second inter- mediate one forms air chambers. Above this second horizontal gir- der the compartments communicate with the water of the Bellot basin. Two vertical water-tight shafts, with manholes and ladders con- veniently placed, afford access to the different portions of the gate. The pivot, which is placed in the invert, is of forged steel. It is the same with the upper pivot of the leaf. The anchor which serves as the hub of the pivot and which transmits to the masonry the pres- sure of the leaves, the pivot step, and the two intermediate counter- forts which maintain the direction of the heel post are of cast steel. The anchorage straps which transmit the pressure to the masonry rest on steel plates 0.0G meter thick, and are embedded in the granite forming the quoin. The air chambers, which are not sufficiently tight to avoid leakage, are cleai'ed by means of compressed air. (209) Hydraulic apparatus. — The Bellot lock is furnished with hydraulic apparatus which works the bridge, the gates, the shiices, and the hydraulic capstans. All these pieces are worked by water under pressure from a central station. The pressure is 52 kilograms per square centimeter. The general arrangement of the apparatus for operating the bridge is as follows: The two supporting beams of the bridge rest upon a box girder, which is itself placed upon a pivot contained in the cylindrical step resting on a metallic wedge. This wedge, acted on directly by a hydraulic press, gives a vertical movement to the cylinder and consequently raises the entire bridge. (Fig. 126). The advantage of this mode of raising the bridge is as follows : The pivot undergoes no displacement with respect to the cylinder, and a constant contact of the metallic surfaces subsists through the whole motion. A leak in the stuffing box would not, consequently, produce any accident, the bridge being held by the wedge in its position. The rotation of the bridge is effected by the action of a pair of twin pulleys. To facilitate this motion and avoid the great friction of the metallic surfaces in contact, the cylindrical step carries in G98 UNIVERSAL EXPOSITION OF 1889 AT PARIS. its upper jpart a stuffing box, forming a tight joint between the pivot and the cylinder. Water under pressure, introduced in the small slots made in surfaces of contact, supports the bridge without rais- ing it, and effects the rotation upon the water itself. The bridge when closed rests on two supports upon each side of the chamber walls at its extremities. During the motion of lifting it turns around a semicylinder fixed under the framing, and engages in a circular cavity made in the upper part of the pivot. During the rotation the bridge rests on its pivot, and upon the breech rollers, which are four in number, two on each side. The amount of water used for lifting the bridge is 462 liters, and for lowering, 378 liters; Fig. 127.— Elevation and plan of a leaf of the Belot lock gates. for turning, 150 liters when a partial power is used, and 292 liters when the maximum power is used. This last is regulated according to the force of the wind, which is the principal obstacle to the motion. The total quantity used for the double operation of opening and closing is 1,140 liters or 1.340 liters, according as the greater or the less power is used. The time required for opening is two minutes. CIVIL ENGINEERING, ETC. 699 (210) The opening of the gates . — The apparatus for moving the gates comprises one for opening, and another for closing them. The first consists of a cylinder with a plunger forming a pulley; the second is identical, with the single difference that the cylinder, in- stead of having a simple plunger, is furnished with a piston which has a much longer stroke, so as to raise the slack given to the closing chain and so allow the passage of ships. Both chains are fastened to the bottom of the lock. After passing around the guide pulleys placed on the gates they pass around the tackles of the opening and closing apparatus, placed side by side, and set in motion by a single valve. The lower guide pulleys are mounted on a swivel block, allowing them to take the different directions, followed by the chain. (Figs. 127 and 128). The quantity of water used for opening or closing is 308 liters. The sluices used to close the culverts between the Eure and B e llt>t basin are cylindrical, 2.08 meters in diameter. The apparatus for working them is calculated on the hypothesis of a change of level of 3 meters ; it consists, for each sluice, of a cylinder with a piston attached directly to the valve rod. The accumulator, to regulate the pressure, has a capacity of 755 liters, and the load corresponds to a pressure of 52 kilograms per square centimeter. A steam engine of 15 horse power is provided, to take the place of the accumulator in case of need. The compressing pumps consist of three sets of plunger pumps, coupled to the same shaft by three cranks 120 degrees from each other. The amount furnished is 53 liters per minute. This quantity allows a complete opening and closing of the bridge every twenty-five 700 UNIVERSAL EXPOSITION OF 1889 AT PARIS. minutes, which is sufficient to guarantee the service in case of acci- dent to the pipes. Cost . — The -cost of the lock is estimated at 1,980,000 francs. The engineers who prepared the project and directed the works are, MM. Bellot and Quinette de Rochemont, chief engineers ; Renaud E. Widmer and H. Desprez, assistant engineers. IRON DOCK SHEDS. (211) Description of the sheds . — The first principle laid down in the construction of the sheds was to diminish, as much as possible, compatible with an economical construction, the number of the sup- ports. The pillars, which rise in the middle of the covered surfaces, take up the place of merchandise and are a notable obstacle to traffic. This hindrance is especially sensible at Havre, where the transporta- tion by carts has an important place. For the southern sheds (PI. VIII) there are two spans of 27.50 me- ters. The roof trusses are spaced 1G meters and united by longitu- dinal lattice girders parallel to the quay. The principal dimensions are given in the following table: Meters. Span of the trusses 27. 50 Distance apart of the principal trusses 16.00 Total height 12. 60 Height of the side doors 4. 75 Construction of the purlins (lattice): Height of the purlins 0. 60 Distance apart of the purlins 1.75 The cost of the sheds varies according to their dimensions. The cost of this shed was 42 francs per square meter, covered. Chapter XXI. — Port of Havre— Iron wave breaker on the BREAKWATER AT THE SOUTH SIDE OF THE OUTER HARBOR. (212) Three sloping breakwaters are placed at the entrance of the port of Havre, two on the north bank and one on the south bank of the channel. To prevent the ships from running into the masonry of these works, and to permit the passage of pedestrians along the channel, a wave-breaker has been constructed on the sill of each of the breakwaters. The northern wave-breakers are of wood, that at the south is of iron. It is 100 meters long and its plan is curved. It has a height of 8.50 meters, measured from the sill of the break- water (at the reference 2.15 meters) to the footpath which forms the coping, at the reference of 10. G5 meters. It consists (Fig. 129) of sixteen trusses G meters apart ; each truss consists of (1) a bedplate, e c, united to a vertical web by two angle Paris Exposition op 1889 — Vol. 3. Civil Engineering, etc.— PLATE VIII. FRAME WORK OF THE IRON DOCK SHEDS AT HAVRE. CIVIL ENGINEERING, ETC. 701 irons built into the masonry; (2) a corner post, a b, formed of two channel irons placed hack to back and united to the plate by two channel-iron beams ; (3) a diagonal brace, e d, equally of channel iron, united at the extremity to the plate, next to a b, and to the two diagonal beams c s and m n, and supporting at its upper extremity the end of the roadway; (4) a horizontal beam, a d, placed in the upper part ; (5) two intermediate pieces, t u, and v x, uniting the cor- ner post and the diagonal brace e d. The corner post has a batter of one-fifth. The trusses are united by flush iron parapets, and also by seven horizontal rails of channel iron, riveted, behind the corner post, upon the diagonal beams and upon the two intermediate pieces ; besides, they are connected on the interior by iron tie-rods. Fig. 129.— Iron wave breaker. Between two consecutive trusses there are three intermediate posts identical with the corner posts and spaced 1.50 meters. They rest upon horizontal rails, and their feet are imbedded in the masonry sill. The corner posts are cased witli oak. The footbridge is formed of of four courses of double T iron supporting an oak flooring. It is furnished with two wrought-iron parapets 0.80 meter high, sur- mounted by wooden hand rail. It is 3 meters wide. The iron is galvanized. The oak casings are protected by large headed nails driven in below just to the level of the water; they are tarred above. The trusses are put together in the breakwater chambers, then raised and fastened without any difficulty. The design was pre- pared and the work directed by MM. Quinette de Rochemont and Maurice Widmer, engineers, under the orders of M. Bellot, engineer in chief. 702 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Chapter XXII. — Canal from Havre to Tancarvilie — Single GATE OF THE TaNCARVILLE LOCK. (213) The canal from Havre to Tancarvilie was built to facilitate commerce between Havre and the Seine and to avoid the dangers of traversing the estuary by "canal barges. It begins at Havre and en- ters the Seine near Tancarvilie, 96 kilometers - below Rouen. Its total length is 25 kilometers. The canal is formed of a single bay. The position of the water level, intermediate between high tide and low tide at Havre, and the high tide and low tide at Tancarvilie, required the construction of two locks, one at Havre and the other at Tancarvilie. In order to be able to lock boats under all circumstances each one of these locks is furnished with gates closing in both directions. The Tancarvilie locks are furnished with four single-leaf gates (Figs. 130-133). These four gates have in plan the same dimensions. They only differ in height. Their upper part is 0.05 meter above the maximum high water which they have to sustain. At their lower part they bear 0.20 meter against the masonry sills. The flood gates are, respectively, 9.85 and 9.25 meters in height. The ebb gates are 7.85 and 7.25 meters. Their maximum width is 4.02 meters. Their length is 18.75 meters. When they are put in the lock cham- ber they rest 0.20 meter behind the face of the wall. Each of these gates is built so as to float, whatever may be the height of the surrounding water above its minimum level, which is that of low tide (2.75 meters). For this purpose a horizontal beam with a flush web is placed at this level, which forms a tight deck and con- stitutes a compartment of the lower part of the gate, where the bal- last is placed, and where the water can never get in. Upon this horizontal deck three vertical lattice beams are placed, upon which are put two horizontal belts. These belts support vertical members on which the sheet-iron skins are riveted. The gate is completed at one of its extremities by a rectangular compartment 2.25 meters long, and is furnished with a trunnion at its upper part and a bearing at its lower part. The trunnion works in a collar fixed in the masonry, and the bearing rests on a pivot fast- ened into the invert. Wooden casings fixed to the gato insure the -tightness of the con- tact of the leaves and sill. Iron culverts, capable of being closed by sluices, allow the water in the canal to penetrate freely into the gate above the tight deck, so that when the water rises above the reference 2.75 meters the equi- librium is not disturbed. Iron shafts rise from the deck just to the upper part of the gate, so that the lower compartment can always be inspected and the bal- last handled. They are ordinarily closed by a tight cover. CIVIL ENGINEERING, ETC. 703 The gates were constructed in the locks themselves, which wero pumped out for the purpose. The compartment, 2.25 meters long, which forms the heel post, was carried from the workshop all put together. It was placed immediately upon the pivot and served as a base for mounting the rest of the leaf. When a gate has to be repaired the sluices of the culverts are closed at low tide. The tide rises, lifting the gate, which is made fast to the side of a barge to avoid any chance of accident, and is then 704 UNIVERSAL EXPOSITION OF 1889 AT PARIS. carried into the dry dock at Havre. It is brought back and placed upon its pivot during ebb tide. At low tide the collar is put on and the culvert sluices are raised. This new system of gate was invented by M. Bellot when he was chief engineer at Havre. It presents several advantages over the system in general use. In certain cases, especially at Tan carville, there is economy in the masonry. Great difficulties are avoided in making the gate itself, the dimensions of which need not have great precision in order that its tightness be absolute. Slight variations in the form of the leaves do not prevent this tightness. When the gates are exposed to the waves or a strong current the miter gates are exposed to shocks which are liable to break the col- lars. The one-leaf gates only beat upon their edges and the chance of accident is very much less. Finally, the operation is simplified, and the closing of one leaf is effected without the attention which is required in miter gates. The superiority of the system is also shown in the various accidents which would have broken miter gates when the single leaf has resisted per- fectly. The designs for the Tancarville gates were prepared and the work directed under the orders of MM. Bellot and Quinette de Rochemont, chief engineers, by M. Maurice Widmer, assistant. The gates were built by M. Baudet, Donon & Co., constructors, Paris. Chapter XXIII. — Slipway built by the chamber of commerce at Rouen for the repair of ships. (211) The port of Rouen has been completely changed since 1887. Actually none of the old quays are left; they have all been replaced by new ones. A timber basin bordered with quays 1,185 meters long with an area of 125,000 square meters has been finished, also a petroleum dock having accessible banks of 1,4G0 meters with six landing stages and an area of 115,000 square meters. (215) The chamber of commerce has lately built a slipway accord- ing to Labat’s system which may be described as follows : The transverse slipway at Rouen is 90 meters long; it can accom- modate ships 95 meters long and weighing 1,800 tons. The slope is 20 per cent ; its width is 51.30 meters, and the travel of the cradle is 31.51 meters, corresponding to a rise of 7.16 meters. It can be traversed in 5, 3£, or 2 hours according to the coupling of the winding gear. When the cradle is at the bottom of its course, the level of the keel blocks is 4.50 below high water; when it is at the top, this level is 1 meter above high water. The inclined plane is formed of forty-two beams (Figs. 134. 135, 138) resting on piles united together by bridle pieces. These beams support steel rails. . 134. — Slipway at Rouen. General plan. Fig. 136.— Hauling machinery. CIVIL ENGINEEKING, ETC. 707 The cradle is formed of forty-two box-girders firmly braced, cor- responding to the forty-two beams of the inclined plane ; each girder carries also a steel rail. Between these two sets of rails, strings of rollers are placed on which the cradle-truck rolls. The cradle is divided into two parts, 49. 3G and 40.44 meters in length, which can be worked together or separately, so as to raise a large ship or two small ones. On the land side the cradle carries a service bridge high enough to be always out of water. The hauling chains, forty in number, are attached to movable sheaves placed midway between the beams of the cradle ; these pul- leys being connected by a compensating cable (Fig. 137) which divides equally the tension between all the chains. This cable passes alter- nately around one of the movable pulleys and a pulley fixed to the cradle. Its ends are attached to the cradle. 1 1 ; I i V/ u 1 m u Ij ! - Fig. 137.— Method of attaching the compensating cable to the cradle. Each traction chain passes round a winch drum driven by an end- less screw, which is itself driven by bevel gearing and a counter shaft (Fig. 13G) extending the whole length of the slip. The engine gives a power of 50 horses measured on the shaft. (216) The rollers . — The rollers are independent of the roadway and the cradle. They are of chilled iron, 0.14 meter in diameter, and 0.18 meter long. Each has a ridge in the middle which runs in a groove in the rails ; they are united by iron rods, which keep them at the constant distance of 0.56 meter apart. Independent rollers have the advantage, over a system of wheels fixed to the cradle, of avoiding the axle friction ; rolling friction only has to be overcome, which is estimated at 3 per cent, besides avoiding inequalities of pressure, combined with simplification in construction. (217) The compensating cable is of steel 50 millimeters in diame- ter; it distributes the total force of traction equally upon forty tension chains. The pulleys are all 0.G0 meter in diameter, the movable 708 UNIVERSAL EXPOSITION OF 1889 AT PARIS. ones sliding in guides 0.20 meter long. In case of tlie rupture of a chain, the movable pulley will be carried to the bottom of its guide, the compensating cable will continue to pull upon it and will distri- bute its load equally among the other chains. In case of the rupture of the compensating cable, the cradle trucks will descend a few centimeters and the movable pulleys will be caught by frames arranged above the guides. The chance of rupture of the cable is small, as it is exposed to a tension of only 3b kilograms per square millimeter. (218) Cost* — M. Labat constructed this slipway at Rouen for 740,000 francs, which was divided as follows: Francs. Earthwork 40, 000 Foundations and inclined plane 240,000 Cradle 180,000 Traction tackle . 220. 000 Engine and shed 60. 000 Total 740,000 Chapter XXIV. — Port of Hoxfleur. (210) Sluicing basin with a feeding tveir for filling it . — Honfleur Harbor is exposed by its situation upon the south bank of the Seine estuary to silting. To preserve the channel, a sluicing basin with an area of 54 hectares has been constructed, filled directly from the sea at high tide by means of a weir with rotating gates. (Fig. 139). The sluicing lock has four openings, each 5 meters wide, separated by piers 2 meters thick, surmounted by a stone bridge. Without entering into the details of its construction and cost it will be inter- esting to know bow it is closed. * For drawings and information I am indebted to the notice of this work pre- sented to the Paris Congress for harbor works by M. G. Cadart, engineer of roads and bridges. CIVIL ENGINEERING, ETC. 709 The apparatus for closing the sluicing lock (Figs. 140 and 141) consists, for each opening: First. Of two guard sluices, 2.45 meters wide, which prevent leakage as well as the inopportune opening of the revolving gate by the waves striking it from without; Second. Of a revolving gate against which the head of water for the sluicing presses when the guard sluices are raised. Each sluice carries two racks which gear with pinions keyed to a horizontal shaft above, which four men turn by means of winches placed on the piers or abutments of the lock. These racks raise first a valve placed at the base of the sluice, which uncovers two orifices 0.20 meter high by 1.70 meters wide; these orifices empty the chamber between the sluices and the revolving gate. The effort to raise the sluices is consequently reduced to that of lifting their weights. The 710 UNIVERSAL EXPOSITION OF 1889 AT PARIS, Apparatus for closing the sluicing lock at Honfleur. Fig. 140.— Vertical half section. Fig. 141.— Horizontal section and plan. T CIVIL ENGINEERING, ETC. 711 rack carries a stop which, when the valve is raised, catches the sluice and raises it to the top of the arch of the bridge. The preliminary operation of raising the two sluices takes two gangs of four men an hour. The axle of rotation of the revolving gate is 0.09 meter from the middle, and in order to facilitate the closing of the gate against the scouring current, there is in the great panel (Fig. 141) a valve turn- ing around a very eccentric vertical axle, which instantly opens under the pressure of the water as soon as the stop which holds it is turned. The great gate, the two panels of which become unequally loaded, rotates suddenly into the plane of the axis of the lock. To close the great gate, it is sufficient, after closing and fastening the rotating valve, to incline it slightly to the lock axis by means of a cable fixed to it and passing round the drum of one of the winches. The differ- ence of head existing within and without the gate causes a difference of pressure on the two panels and closes the gate. (220) Construction of the gates . — Each gate is made up of uprights of oak 0.40 meter thick, firmly held at their extremities by beams of double T iron forming bridle pieces. The plates of these beams are embedded in the wood, so as to avoid any projection. The uprights are held together by three horizontal bolts extending the whole width of the gate ; two belts of wrought iron strengthen the whole. The axle of the gate is formed by a double T beam terminated by two pivots and joined with horizontal bridle pieces. The pivots are of steel, 0.210 meter in diameter. Cost . — The cost of constructing the gates and sluices of the basin, with the winches, etc., amounted to 132,109 francs. (221) The feeding weir . — The problem to solve consisted in intro- ducing layers of surface water into the basin at will during high tide. Preliminary experiments showed that these layers are always very much clearer than those at the bottom, and that by their use the basin would be prevented as much as possible from silting up. As there were only 2j hours at each tide which could be used, a layer of water 0.60 meter in height by 100 meters in length suffices to fill the basin. This length was divided into ten openings, 10 meters wide, closed by three movable gates (Fig. 142). These gates, turning around a horizontal axis, are each held by a chain fixed to their upper parts. All these chains pass around guide pulleys, and their extremities are fixed to the same frame mounted on rollers, so that the reciprocating motions of the frame give simultaneous movements of rotation to all the gates. Hydraulic presses move the frames, either to raise or to lower the gates. A weir with a movable crest is thus obtained, which allows the introduction into the basin of a layer of water of constant thickness, notwithstanding the variations of the sea level, which do not exceed 0.40 or 0.50 meter during the time of filling. 712 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Description of Fig. 142. — A, movable gates, turning around a horizontal axle placed at the lower part near the flooring ; each gate consists of eight vertical beams of plate and angle irons connected above and below by two similar crossbeams : it is covered on the upstream side with a plate iron skin, 8 millimeters thick, terminating below in the form of a semicylinder, so as to always remain in contact with the wood casing built into the flooring sill. On the downstream side, at a height of 1.70 meters, is a horizontal beam made of plate and angle irons fixed to the vertical beams ; to this crossbeam the traction chains are attached. The end verticals of the gate are cased with wood. The gate is represented in the figure in its vertical position; that is, when the weir is closed; and also a gate in a horizontal position, although in reality it never takes it. The figure shows the inclination of the gate during the process of filling the basin when the level of the sea is 11.82 meters. a. Forked bearings and journals, two for each gate. The form of these bearings allows the gates to be removed for repairs without having to take them apart under water, c. Plate iron apron, 45 centimeters wide, hinged to the base of the gate and furnished with a leather band which covers the joint of the gates with the sill. This apron drags upon the flooring, following the motions of the gate, and prevents ob- structions which might produce accidents at the moment of lifting, d. Two ten- nons for each gate, fixed to the upper beam, just over the rotation journals. These tennons are forged in a single piece, with a plate which serves to bolt them upon the web of the beam ; it is by means of these tennons that the bolts hold the gates fast against the frame so that they may be able to sustain the pressure of the rising tide while the storage basin is empty. B. Framework holding the moving mechanism for rotating the gates. It is forme I of two vertical lattice beams 1.25 meters high ; these beams, spaced 60 centimeters apart, are jointed below to a horizontal beam, 1.20 meters wide, having a flush web pierced with holes for the passage of the chains. These three beams are braced by cross partitions of iron, 8 millimeters thick, numbering six per span. A third vertical beam, 60 centimeters high, sustains the crossbeams of the footbridge. These latter are united by four courses of crossbeams supporting the planks of the service bridge and the rails for a moving crane. On the reservoir side is a sidewalk on corbels, projecting 70 centimeters, and held by plate iron brackets and angle irons. D. Guide pulleys of the chains; they are cast-iron grooved chain pulleys, their grooves lined with bronze. They revolve on iron shafts, 60 millimeters in diameter, having supports cast in a single piece and bolted under the web of the horizontal beam. E. Guide pulleys of the chains, of the same model as the preceding but keyed to the shaft. The plumber blocks, inclined at 45°, are fixed at 60 centimeters apart upon the upper plates of the vertical beams ; the shaft of these pulleys is 65 millimeters in diameter at the bearings and 90 millimeters in the middle. The plumber blocks are furnished with a half lining in bronze, and an iron cap. F. Reciprocating frames for rotating the gates simultaneously. Each frame is formed of two plate-iron beams 300 millimeters high, 75 thick and 250 apart, united by transverse ties G ; a gate chain is attached to each. G. Cross girders, having their ends bolted upon the sides of the moving frame so that they can be removed. The chains are fixed upon these cross girders by means of turn-buckles which allow their length to be regulated, so that at the closing all the gates shall come against the framework. The frame, by its reciprocating mo- tion, determines the simultaneous rotation of the gates. The chains are round, 30 millimeters in diameter. They contain, each one, 59 links, 85 by 38 millimeters of opening, and two end links 124 by 38 millimeters. R. Iron rollers, twenty for each frame. These rollers are 18 centimeters in diam- eter, 42 long. Their iron axles, 4 centimeters in diameter, turn in boxes fixed on the vertical beams of the frame. b. Chair supporting the bolts. t. Bolt shaft. '■ 142.— Partial elevation and cross section of the feeding weir gates of the sluicing basin. CIVIL ENGINEERING, ETC. 713 Sluicing basin at the pout of Honfleur. 714 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (222) The feeding weir consists of: First. Ten openings, formed by nine piers and two abutments. These openings are each 10 meters wide and 11.75 meters long. Their invert in the highest part is at the reference 14 meters,* so as to allow the filling of the basin in the lowest tides, the highest attain- ing the reference of 13 meters. The flood gates occupy a space of 10.20 meters wide and 6.45 long, corresponding to each opening. A building on the central pier contains the hydraulic machinery and the lodging of the machinist. Second. Thirty iron flood gates, three for eacli opening, turning on horizontal bearings embedded in the invert of the opening. These flood gates rise from the invert (reference 14 meters) to the level of the equinoctial high tide, which reaches the reference 11.82 meters. Third. An iron frame work built on piles and supporting the upper edge of the flood gates ; it carries the guide pulleys of the lifting chains and the rollers upon which the frames move, and forms at the same time a bridge of communication on which a tliree-ton crane runs, which allows any piece to be taken out and replaced very rapidly. Fourth. The. transmitting mechanism, consisting of chains and a movable frame. This last is jointed to a rod driven by two twin presses moved by water under the pressure of 70 kilograms per square centimeter. The other extremity of the frame is drawn by a counterpoise intended to overcome the passive resistances of the apparatus during the opening of the flood gates. Fifth. The mechanism for keying, intended to maintain the flood gates against the frame work, to permit them to resist the pressure of the rising tide just to the moment of filling. This mechanism consists of a shaft carrying a series of pins, two for each flood gate, driven by a little special hydraulic press. (223) The movement of the gates is effected by means of two cou- pled hydraulic presses. A little double-cylindered steam engine of 9 horse-power works the pumps for filling the accumulator, or, if necessary, drives the water directly into the cylinders of the great presses. The accumulator contains 600 liters of water at a pressure of 70 kilograms per square centimeter. The water discharged by the hydraulic apparatus during the low- ering of the gates is collected in an iron tank placed on brackets let into the wall of the engine room. From this reservoir the pumps take the water required for their use. This is an important economy, since the apparatus has to be fed with fresh water brought from the city. __ *The datum plane for Honfleur is 16.087 meters above that adopted for the rest of France. CIVIL ENGINEERING, ETC. 715 The complete operation of the weir consists : first, at the moment of high tide, the basin being empty, in gradually lowering the gates, so that their crests shall be covered by a sheet of water 0.00 meter thick; second, in raising the gates when the basin is full, that is to say, generally, with a difference of level if not nothing at least in- significant. (254) Cost . — The expense of constructing the feeding weir amounted to $1,224,888.30 francs. The sluicing operations are entirely successful, and it is only suffi- cient to make one or two at each tide to keep the outer channel clear. The feeding weir -works regularly, but, at the same time, the in- tense current produced on the approaches to the weir, when the re- volving gates are lowered, does not exclude absolutely the lower turbid layers of water. The preliminary plan was made by M. Arnoux, and the work was directed by MM. Leblanc and Widmer, engineers. The contractors were M. Hersent for the lock, and the Fives Lille Co. for the iron work of the weir. Figs. 139-141 are taken by permission from the Portefeuille des Pouts et Chaussfies. Chapter XXV. — Port of Honfleur — Siphons between the STORAGE BASIN AND THE FOURTH LOCK — AUTOMATIC SIPHONAGE. (225) As lias been stated, Honfleur Harbor is exposed, by its situa- tion upon the south bank of the Seine estuary, to Considerable silting up, against which constant efforts have to be made. The storage basin of 54 hectares affords the principal means of keeping the passes free by sluicing. When great sluicings are not made, communication is opened be- tween the docks and the storage basin, in order to increase the effi- ciency of the sluicing given by the navigation locks, and to reduce the silting of the docks by raising as much as possible the level of the water of these last, before the opening of the ebb gates and in- troduction of the flood, which is very much loaded with sand. This communication ought not to be opened more than five or six times a fortnight, to reestablish the level in the dock when this level has fallen below that of the storage basins on account of the sluicing. The level of the storage basin being generally above that of the dock, there was great interest in making a tight closing. This motive, joined to that of economy, led to the adoption of a system of siphons. These siphons are six in number. The saddle is placed above the ordinary level of the basins (12.30 meters). (226) The apparatus for filling and emptying is based upon the fol- lowing experiments. When a small hole is made in the wall of a siphon in operation, in the portion where the pressure is below that of the atmosphere, the siphon does not become clear if the hole is 716 UNIVERSAL EXPOSITION OF 1889 AT PARIS. very small. The external air is sucked by this orifice into the siphon, and it issues in great bubbles which break upon the surface. By enlarging the orifice, or by piercing other holes near the first, we finally clear, i. e., empty the siphon. In opening the sucking orifice to bring about the clearing, we ob- serve that the flow of the latter diminishes progressively until it at- tains a value very near zero, and, for an opening slightly more, the clearing is nearly instantaneous. It is evident that this principle may be applied to the filling of siphons of great capacity. Small siphons are filled easily and rapidly, either by the emptying of a reservoir full of water, or by means of a sucking-pump. A lit- tle siphon pierced with a sucking orifice properly arranged will work as a filler for siphons of greater dimensions, if we unite the pierced sucker of the first to the top of the second. To stop the action it will suffice to clear the siphons by putting them in communication with the atmosphere by an orifice sufficiently large. (227) This stated, the process of filling can be understood ; it is as follows: A valve a (Fig. 143) is opened which allows the water in the reservoir A to flow into the pit P, and thence, through the con- duit B, into the lower bay; at the same time the upper part of the leservoir A is connected with the top of the filling siphon, No. 1. The capacity of the reservoir A is calculated so that all the air con- tained in the siphon is sucked in and replaces the water which runs out by the valve a. When the siphon is filled, which is indicated by a gauge, the stopcocks and the valve a are closed. The siphon No. 1 contains an air sucker formed by a copper pipe 0.02 meter in di- ameter, which goes through the siphon wall perpendicularly, and, CIVIL ENGINEERING, ETC. 717 returning along the axis of the siphon, terminates a litte beyond the top by a rose. The object of this arrangement is to divide the air at its entrance into the siphon and to obtain the rapid drawing of air bubbles toward the discharge. The aggregate of all the ori- fices of the rose is above one-tenth of the section of the pipe of 0.02 meter. When the difference of level is equal to or above 0.80 meter, experience shows that this sucker may be put in free communication with the atmosphere without clearing siphon No. 1. For siphons of the same cross-section the size of the sucker orifice depends on the difference of level, and the sucker belonging to siphon No. 1 is contrived for a difference of about 1 meter. The sucker just described is put in communication with a siphon No. 2, which has the same diameter as No. 1, but is placed 0.25 meter higher. The air contained in No. 2 is drawn out by this siphon and the siphon fills, as the corresponding manometer indicates. This siphon contains a sucker identical with the first, but with a slightly less section ( 0.015 meter instead of 0.02 meter). The two sucking siphons are putin communication with a third siphon, called a cul- vert siphon ; when the manometer indicates that the first culvert siphon is filled, a second culvert siphon, connected with the first, is filled, by taking care not to uncover a new distributing orifice until after the complete filling of the preceding siphon. One man fills all the siphons. This operation requires from ten to twelve minutes. The siphons filled, the reservoir A is filled by putting it in com- munication on one side with the siphons and on the other with the upper basin. All the air contained in this reservoir is sucked out by the siphons and replaced by water from the upper basin. The communication should be closed when the water in both basins is sensibly at the same level. To stop the action of the siphons they are cleared by opening the stopcock of 0.02 meter, which puts them into communication with the atmosphere. The complete clearing takes place in seven or eight minutes. ( 228 ) Automatic filling. — Independently of the process of filling that has just been described, and which has worked since 1884 , these siphons fill naturally and automatically whenever the sluicing basin is filled. The water then covers the saddle of a siphon 0.0G meter in diameter, which goes down into the well and fills by overflow. This siphon fills a second of 0.13 meter in diameter placed 0.33 meter above it; and these two siphons united fill three others of 0.20 meter in diameter placed at 0.28 meter above the second. This col- lection of fillers is united with siphon No. 1, which is 0.50 meter in diameter, by a stopcock. When this cock is open all the siphons fill in one hour and a half or two hours, for a difference of level which ought to be above 0.40 meter. This is the necessary time for the de- cantation of the water taken at the moment of high tide in the sluic- ing basin. This collection of filling siphons, arranged in a series, has worked regularly without aid of any person since the year 1886 . 718 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The collection previously described only works occasionally. The siphons were planned and built by M. Picard, under the di- rection of M. Boreux, chief engineer. Chapter XXVI. — Traversing bridge over the dock locks at the port of St. Malo-St. Servan. (229) Position and general arrangement.— The new road uniting the cities of St. Malo and St. Servan passes over the two locks 18 meters wide, of the two docks, by means of traversing bridges moved by water under pressure. These bridges are similar, each one having a total length of 38.80 meters— 22.80 meters for the span and 1G meters for the breech. The total width is 8 meters, the width of the wagon road 5 meters, and that of the sidewalk 1 meter. Fig. 144. — Section of the traversing bridge — Section A B of the box girder- -Sections C D and E F of the lifting press. Idie roadway is carried by two principal girders with flush webs, having the form approaching that of a solid of equal l’esistance; the maximum height being 2.814 meters. The upper flange is curved, the lower straight. The cross girders are spaced 2 meters. (230) The lifting press (Fig. 144), 1.06 meters in interior diameter, is placed vertically in a masonry pit exactly under the centre of gravity of the bridge, and supports an iron box girder on whose ex- tremities cast-iron sleepers are placed directly under the principal girders, and designed to support the whole weight; laterally itis fitted to pieces of iron which move in vertical guides. CIVIL ENGINEERING, ETC 719 In order to diminish the quantity of water at the pressure of GO atmospheres Mr. Barret, engineer of the docks at Marseilles, invented a special apparatus, called a recuperator, which forms, with the lift- Fig. 145. — Diagram of the operation of the recuperator. ing press, a sort of hydrostatic balance, allowing the work produced by the descent of the bridge to be stored up and utilized for raising it afterwards. 720 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (231) The recuperator . — The working of the species of hydrostatic balance of the recuperator press may be represented by the diagram (Fig. 145). The press A communicates directly, by the pipe T. with the recu- perator B. The latter consists of a vertical cylinder, in which a piston supporting a loaded box, C, moves. The load is regulated so that the bridge, P, in descending drives the water of the press under the piston of the recuperator and raises the whole system. A pipe, o, allows water under pressure to be introduced at will into the an- nular space over the piston of the recuperator, between the piston rod and the cylinder, or to allow this water to escape. In the case of the introduction of this water the pressure exercised in the an- nular space is added to the weight of the load. The piston of the recuperator descends and drives the water into the lifting press. In case of the escape of the water the pressure in the annular space is relieved; the Aveiglit of the bridge again becomes greater and raises in its turn the piston and its load. The preceding theoretical arrangement was modified in practice so as to avoid having to take away the load of the piston each time that it was necessary to change the packing. The apparatus is re- versed, the piston and piston rod are fixed, while the cylinder is mov- able and carries the load; so that to change the packing it is only necessary to raise the cover of the cylinder. Fig. 146 shows the arrangement adopted. The piston rod, A, is a hollow cast-iron cylinder 48 centimeters in diameter, which rests upon a circular foot 1.40 me- ters in diameter, strengthened by flanges. The rod is furnished above with iron rings, forming a piston of 54 centimeters in diameter, packed Avitli tAvo leather collars all kept in place by a cast-iron fol- lower bolted down. (Fig. 147). The interior of the rod (Fig. 146) forms a com- munication, through the pipe, a, between the lifting press and the movable cylinder of the recuperator. This last is 54 centimeters in interior diameter and 80 millimeters thick. It has an enlargement beloAV and a stuffing box for the pas- sage of the rod. To bring the Avater from the accumulators into the annular space, C, left betAveen the rod and the cylinder, the cylin- drical passageway, B, in the piston rod itself, forms the prolongation of the pipe, b, and leads into the annular space through a hole pierced laterally beloAV the piston. The base of the cylinder carries externally tAA r o flanges which form a circular grooA’e for holding in place the iron plate Avhich serves as the bottom of the loaded box. This plate is made of two pieces put together Avith bolts. The box is cylindrical, of plate-iron 8 millimeters thick, 2.352 meters in diameter, and 3.25 meters high. It Fig. 147.— Horizontal section of the recu- perator press. CIVIL ENGINEERING, ETC. 721 is guided above by a cast-iron support having two arms with shoes, E E. at their extremities, which run on two cast-iron guides, 3.45 meters long, built into the masonry. Three oak frames placed above each other, at the foot of the rod. form a support 1 meter high upon which the loaded box rests when it is at the bottom of its course. (■-232) The withdrawal and replacement of the bridge requires, be- sides the working of the hydrostatic balance formed by the central press and the recuperator, some accessory operations. We must be able, in case of necessity, to lift the loaded box to the top of its course, and on the other hand lower or lift separately the box girder, and in case of repairs, the plunger of the central press. These operations are accomplished by the accumulators and the distributing apparatus placed in the pavilion and arranged for this purpose. The weight of the recuperator is less than that of the bridge. When the bridge is to be raised, the box being at the top of its course, it is sufficient to open the valve, which puts the annular space compirsed between the piston and its cylinder in communication with the water under pressure, so that the latter, acting on the lower face of the box, compensates for the difference between the weight of the bridge and that of the box, and produces the upward motion of the bridge. To lower the bridge it is sufficient to allow the water to escape from the annular space; the bridge descends then by its own weight and lifts the -recuperator. The horizontal motion of the bridge is ob- tained by two hydraulic presses fixed horizontally on the vertical walls of the box girder (Fig. 144) and moving with it. They carry at each extremity a tackle block with three pulleys, around which the traction chain passes. One serves for the advance motion and the other for the return. The conducting water pipes form a joint with the cylinder presses. The bridge can move upon two pairs of rollers fixed just behind the position it normally occupies — that is, when the pass is closed— and upon four pairs of movable rollers, which are made to slide upon a cast-iron frame by the action of a hydraulic press, which pushes them under the bridge as soon as it is raised. The rollers are fixed in pairs upon a balanced beam, so that the weight of the bridge shall be divided equally over the numerous points of support. The rectilinear movements of the bridge are limited at each extremity by buffers built into the masonry. The complete withdrawal and replacement is made in three or four minutes. One man is sufficient. He is placed in the pavilion which contains the operating keys, the recuperator, and a service hand pump, intended to force in, if necessary, water enough to move the bridge. The water under pressure is brought through one pipe and returns in another to the pavilion constructed between the two roll- ing bridges and containing the pumps and accumulators. (233) Opening and closing the bridge . — The pavilion contains three H. Ex. 410— VOL ill 46 UNIVERSAL EXPOSITION OF 1889 AT PARIS. 7'22 pieces of distributing apparatus. When it is required to open the pass the lockman moves the valve of the first apparatus, and the water under pressure from the central machine and the recuperator is forced under the piston of the central press, which raises the sleeper and consequently the bridge. Then he opens the valve of the second apparatus and the movable rollers slip under the bridge; lie then lowers the bridge upon the rollers by opening and discharging from the lifting press. When the bridge rests upon the rollers he prolongs a little the discharge of the water so that there is a play of 0.03 meter between the sleeper and the plates of the beams. Finally he opens the valve of the third apparatus and the rectilinear mot ion is produced. When it is required to put the bridge in place, the lock- man opens the valve of the third apparatus and the bridge is brought vertically over its first position ; then he opens the valve of the first apparatus, which lets the water under pressure into the central press. When the bridge is sufficiently raised the valve of the second apparatus allows the movable rollers to be brought back; then, on opening the valve of the first apparatus, the bridge sinks to its normal position, and at the same time the water in the central press runs into the recuperator and is stored there. The total weight of the bridge is 181,500 kilograms; the price, including the mechanism, the recuperator, and the piping, amounts to 200,000 francs. This bridge was planned and made by M. Robert, engineer of roads and bridges, under the direction of M. Mengin, chief engineer. Figs. 145-117 are taken by permission from the Portefeuille des Pouts et Cliaussdes. Chapter XXVII. — Hydraulic works and pneumatic founda- tions made at Genoa. (234) Graving docks and accessory tvorks . — The Duke of Galliera bequeathed to the Kingdom of Italy several million francs for the improvement and extension of the harbor of Genoa. Among these improvements were particularly specified the construction of two graving docks, capable not only of answering the present require- ments but also those which might arise in future. A special com- mission of engineers was appointed to find the best means of fulfill- ing these obligations. The commission, considering the exceptional technical difficulties which this work presented, advised the opening of an international competition requesting proposals for the work, with the processes for its execution, and requiring guaranties there- for. The administration adopted this advice. Eight competitors responded to this invitation of the technical commission, and after a long examination they reported in favor of the project presented by MM. C. Zschokke and P. Terrier. The works to be constructed include principally the Quai des CIVIL ENGINEERING, ETC. 723 Graces, the western quay, the two docks, the quay which unites them, the pumping machines, and the caisson gates. (235) The Quai des Graces is 200 meters long and 75 wide. Its coping is 3 meters above the level of the water. The retaining wall is formed of masonry piers founded by compressed air upon rock at the reference — 8 and united by brick arches. In the space of 12 meters between the piers the filling of the quay is protected by stone pitching. (236) Western quay . — The foundations of this quay having been previously made the wall alone had to be constructed. (237) Graving docks . — The two docks are parallel. The distance apart of their axes is 77.37 meters. Their principal dimensions are as follows : Maximum interior length at the quay level including the entrance chamber. Width at the same level Width of entrance at the same level Width at the water level Width at the sill Height of the water on sill at mean tide Height of water on the lowest point of the dock No. 1. No. 2. Meters. Meters. 1 ~9. 38 219.94 29.40 24.90 25.28 18.48 24.80 18.00 21.06 14.64 9.50 8.50 10.00 9.00 The two docks, although of different dimensions, are constructed in the same manner. Each entrance has two recesses for the caisson gate. Dock No. 2 is provided with two other recesses which are respec- tively 90 and 130 meters from the entrance, and which allow a second gate to be placed therein, thus dividing the dock into two separate chambers, 90 and 110 meters, or 130 and 70 meters. The transverse section of the gate chambers is a trapezoid. The interior lias five altars in dock No. 1, and four in No. 2. The wells for pumping out the dock are in the walls toward the en- trance. The eastern wall of dock No. 2 contains a special culvert for discharging the water of the two compartments independently, which, the second caisson gate allows to be placed at the bottom of the dock. The walls approach and close in the shape of an ogive at the end opposite the entrance. From one part to the other of the ogive inclined planes, parallel to the axis of the docks, allow the descent of wagons to the bottom in order to transport the material required for repairing ships. These inclined planes are flanked with staircases for the descent of the workmen. The invert of the docks has a longitudinal declivity of 1 to 100. It has the same transverse slope from the axis toward the walls, along which little gutters take the drainage to the discharg- ing well. 724 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The revetment for all the parts of the work which are exposed to shocks or subject to strains is of hewn stone. The other parts of the revetment are of brick. The flooring is of sandstone on brick foundations. (238) Head walls . — The head walls are united with the Quai des Graces and the western quay by continuous walls, founded at the reference —8. Pumps . — The pumping house is placed between the two basins at the entrance. Three centrifugal pumps, driven by as many com- pound condensing engines, are placed in a dry pit at the reference —8. Two of these pumps can clear either basin filled with water, in five hours, which corresponds to a discharge of 4,000 cubic meters of water per pump per hour. Two other pumps, driven by special motors, provide for the leakage ; each one can discharge 250 cubic meters per hour. The steam is furnished for these machines by six boilers. (230) The three caisson gates are of plate steel. They are sur- mounted by a bridge large enough to give passage to wagonettes or cars. They are furnished with a number of sluices sufficient to as- sure the filling of one of the basins in an hour at the most. EXECUTION OF THE WORKS. (240) Character of the foundation . — The soil upon which the works had to be founded is a calcareous stratified rock of the Miocene for- mation, with very shelving banks, covered with fine layers of sand and rock ruins. The formation is very variable, both as to the quality and hardness of the rock. The water has washed away the soft parts and left the hard, so that the surface of the rock presents a series of projections with the hollows tilled with sand and fragments ; hence the same arrange- ments had to be made as if the rock had been completely porous, by substituting a b^ton bottom for the natural soil. The submarine operations Avere as folloAvs : First, the blasting of the rock ; second, the removal of the sand and rock blasted, and, third, the laying of the masonry on the bottom thus cleared. Two solutions of the problem . — The thickness of the banks and their great depth under water precluded, for the boring, any arrange- ment employing machinery set up above the level of the water. The same circumstances Avould have rendered the extraction of the pieces of rock by dredges very difficult. Again, the sinking of b£ton under water at such great depths would have given only mediocre results. Recourse must be had to pneumatic processes. Two solutions presented themselves. One was that adopted for the construction of the docks at Toulon and for the basin at Saigon. It consisted in con- structing the masonry of the flooring and side walls upon several CIVIL ENGINEERING, ETC. 725 great floating caissons and producing by the increasing load of this masonry their gradual immersion and descent into the soil at the bottom, then Ailing the working chamber with bet on when the cut- ter had arrrived at the chosen bottom upon which the work was to be erected. This is in reality the extension of the process in use for the foundation of bridge piers. It is perfectly satisfactory when absolute tightness is not required in the work, but this is not the case with the dry-dock. It is impossible to disguise the fact that the iron imbedded in the masonry, the plates forming the diaphragm between the upper masonry and the bdton Ailing the working cham- ber. exclude precisely the conditions of homogeneity and continuity of the masses which such constructions are expected to fulflll. The metal interposed must necessarily alter with time and produce leaks. It is also very difficult to spread upon such a great floating caisson the increasing load of masonry in a manner sufficiently uniform to avoid all changes of form, and to work without ever deviating from a horizontal plane, flrst in grounding the caisson upon an irregular bottom, and then in building it upon a rocky bottom. The changes of form and the Assures which they would cause were particularly to be feared at Genoa, where the immersion had to be made in a part of the harbor not entirely sheltered against the waves and where the blasting of the foundations presented great difficulty. Another solution must be found. That which the contractors proposed, which avus adopted by the technical commission, consisted in removing the rock and laying the masonry under water in great di\'ing-bells fur- nished with the apparatus necessary for rapidly effecting the hori- zontal or \ r ertical displacement of those machines best adapted to the boring and extraction of the blasted material and the introduc- tion of new. This process permitted the direct building of the foundation upon the prepared bottom, avoiding risks of change of form and of rup- ture in the perfectly homogeneous and continuous masonry, in which no portion of iron remained imbedded. ItalloAved the different por- tions of the Avork to go on independently. These Avere the moti\”es which decided the contractors to adopt this solution and to construct for realizing it : First. A movable caisson for blasting out the rocks. Second. Tavo other movable caissons for the construction of the walls for the quay and basin. Third. A great floating caisson for the extraction of the rocks and for the construction of the flooring. (241) Caisson for blasting out the rocks . — The blasting caisson (Fig. 148) is 20 meters long and G.50 meters Avide. The working chamber does not differ from those ordinarily used for the construc- tion of bridge piers, except that the Avails are lighter, as they do not have to bear the load of the masonry above the bottom. UNIVERSAL EXPOSITION OF 1889 AT PARIS. 726 Pigs of iron placed between the beams of the roof balance the under pressure and keep the caissons on the bottom. Two horizontal plate-iron cylinders, 2 meters in diameter and 5.50 meters in length, are fixed above the frame parallel to the transverse axis of the caisson and in symmetric positions in respect to this axis. They are open at their lower parts. A tube connects one with the other and puts them in communication with the compressed-air pipes which supply the working chamber. Water is allowed to ascend in the cylinders, to fill them, when the caisson ’• kept at the bottom for blasting. The water is forced out by me? as of compressed air when the caisson is to be raised and changed in position. This substitution of water for air in the cylinders, which has for effect the gradual augmentation of the water displaced by the sys- tem, can be regulated at will and continued just to that degree neces- sary for the equilibrium of the load, so as to assure the stability of the caisson upon the bottom ; the slightest effort then suffices to lift the apparatus. The caisson is surmounted by tAvo shafts with air locks for the entrance of workmen. A third is reserved to add, if necessary, a lock for the materials extracted. The caisson is suspended by twenty-four chains to as many jacks resting on a lieaA r y staging, which in turn rests on tAvo barges fur- nished with all the apparatus necessary for a rapid displacement. (242) Boring apparatus . — The boring apparatus made by M. Sul- zer at Winterthur, is arranged in the following manner: The plat- form of the caisson is divided lengthwise into three equal belts by four double T-irons, the loAver wings of which serve as a rolling track for three trunnions on rollers. Each of these trunnions has a collar at its loAver part to which one of these boring machines is sus- pended by a joint. The trunnion moves the length of the platform, the collar slightly unscreAving along the whole trunnion, so that the point of articulation of the boring machine may occupy every posi- tion of a plane Avithin the limits of one of the three belts, and the tool may also turn in each of its positions in all directions so as to pierce sloping holes at will. The boring machines are driven by water under pressure brought from an accumulator on the boat, by jointed piping which descends along the central shaft, runs along the platform, and feeds the tools in all positions and inclinations giA r en them. As the boring progresses the boring tool is prolonged by hollow rods screwed together. The diameter of the boring bit is 10 centimeters for the holes exceeding 2 meters in depth, and (5 cen- timeters for the others. Tavo double-acting twin pumps, furnishing water under pressure, are placed in a boat fastened to the cais- sons. They are driven by two portable engines of 25 horse power each. The water, taken from the sea, is driven into an accumulator and kept under pressure by the steam taken from the engine boilers. The steam acts on the upper surface of a plate, fourteen times the Port of Ge iio.-iiun^versesecuon or uie movable caissons used fordrilling the rock pontoons supporting the caisson; U, lock for the workmen: B. drills < Brandt’: pressure is conveyed to drive the boring machines. H. Ex. 410 — vol i ix — Fare page 727. Blasting caissons. f\ I l «‘Pun>ose of submarine blasting. X, the working chamber; Y. the lightering chamber; Z. ■' n), 31, tuo steam engines, driving pumps feeding an accumulator from which water under CIVIL ENGINEERING, ETC. 7L>7 section of the piston, which transmits directly to the water the pres- sure of 00 or 70 atmospheres, necessary for boring. This arrange- ment avoids the great load which would have to be placed upon the barge with an accumulator so weighted as to be capable of giving such a great pressure. When the boring of the holes has been com- pleted*, just to the required depth, over the whole surface covered by the caisson, they are filled with cartridges or dynamite gelatin, the wires are attached to a floater which is passed under the cutter, the Fig. 149.— Port of Genoa. Transverse section of the movable caisson. caisson is raised and moved by the supporting barges, and tire mines exploded by an electric battery. By experience in regulating the distance between the holes and the amount of the charges, they suc- ceeded in giving to the fragments of rock broken off the dimensions most convenient for use. (243) Movable caisson for the construction of the quay walls. (Figs. 149-150). — These two caissons, which served also for the removal of 728 UNIVERSAL EXPOSITION OF 1889 AT PARIS, Fio. 150. — Elevation and longitudinal section of the movable caissons used in laying the masonry under water. X, the working chamber; Y, the lightering cham- ber; Z, the pontoons supporting the caisson ; U, S, C, locks for the men, materials, and be ton, respectively. poir H. Ex. 410— vol in— Face page 729. >.3 and 154. ock ; for description see p. 729. I Figs. 155 and 156. CIVIL ENGINEERING, ETC. 729 the broken material, were 20 by 6.50 meters, and 18 by 5. GO meters. They were constructed, ballasted, and suspended like the one just described. They were provided with a man lock, and a second lock for the removal of the spoil and the introduction of the materials, and a third for the introduction of b£ton. (244) At Rome, before the invention of Zschokkd’s excavation lock, the spoil was removed through locks placed upon shafts 0.70 meter in diameter. These shafts were supplied with iron ladders in- side. serving in case of need for the removal of the spoil and for the use of the workmen. The spoil loaded into buckets of about 35 liters, was raised by an elevator fixed to the upper part of the lock and put in motion by a cable transmission. The insufficiency of this method, especially for raising large blocks, was immediately recognized, and the company put into use its newly invented excavation lock, which merits especial considera- tion. It is represented in Figs. 151-156, in the new form which it had at the works at Genoa and Bordeaux. (245) Description of the excavation loch . — This lock forms the upper part of a shaft 1.05 meters in diameter, having its sections united by external angle irons. A circular interior angle iron, pro- jecting into the shaft, is placed at the bottom of the lock. An iron plate 0.90 meter in diameter, surmounted by two frames supporting a turning bucket, is suspended at the end of a chain passing round the drum of an elevator placed at the top of the lock. The bucket and its supporting plate move freely through the height of the work- ing chamber and the shaft, but are stopped in their upward move- ment by the striking of the plate against an india-rubber ring which lines the lower face of the projecting angle iron below the lock. At the moment when this striking is produced an automatic motion of levers acting upon a double stopcock puts the lock in communica- tion with the outer air. The escape of the compressed air produces an increasing pressure and a complete adhesion between the plate and the angle iron. The outside rolling door, bordered with india- rubber, which the interior pressure no longer holds against the cyl- inder, is opened. The bucket is turned toward the opening and its contents (400 liters) discharged. The bucket is then tipped back, and the exterior door closed ; by a reverse movement of the stopcock, the communication bet ween the working chamber and the lock is re- established. The compressed air rushes into the lock. The equi- librium is again established on both sides of the moving plate, and nothing stops the descent of the bucket into the working chamber. The elevator is raised by a portable engine and cable, when the local conditions allow this mode of transmission, as was the case at Rome. Elsewhere the motion is transmitted from a Sclimied motor fixed upon the platform of the lock and worked sometimes by compressed air. and sometimes by water under pressure. 730 UNIVERSAL EXPOSITION OF 1889 AT PARIS. This little light lock, very easy to move, allowed the rapid removal of very considerable quantities, and quite large blocks without re- quiring for its management the presence of a single man in the compressed air. It was not arranged for the passage of the work- men who went in easily through the old entrance, the lateral locks for removing the spoil having been taken away. The new excavation lock, employed in its first form ten years ago, has been very much improved, and, in view of the works executed at Bordeaux and Genoa, it is placed in the exhibition (Machinery Hall) with its latest improvements adopted in 1888. The chain drum is driven by means of two friction wheels by a Schmid -water motor taking its supply directly from the city reser- voir situated 100 meters above the sea. The two caissons served not only to introduce the bdton, but also to lay the masonry and the revetment in brick and cut stone of small dimensions. When the hewn stones were of too great dimensions to be carried in through the locks they were lowered outside by means of a floating crane, the caisson, which had to be removed for this operation, was replaced, and the workmen found in the working chamber the stones to be set up. (24G) Great floating caisson . — The great floating caisson shown in Fig. 157 is intended for raising the fragments of rocks made by the explosion of the mines just described, and for laying the btfton flooring. It is 38 meters long and 32 meters wide, that is, 1,210 me- ters of surface. These dimensions were required on account of those of the flooring. The widest of the two floors is 36 meters, that is, 2 meters less than the length of the caisson. The caisson, which is now floating in the port of Genoa, consists of three essential parts: First. The working chamber, 2 meters high, surrounded by two tight plate-iron envelopes, one vertical, forming the exterior walls, the other inclined, covering the interior faces of the braces from the roof to the cutter. Second. The equilibrium chamber, which rises above the first to a height of 3 meters. It is completely enveloped with plate iron and traversed by shafts giving access to the working chamber. Third. The iron reservoirs or regulating pits, which rest upon the equilibrium chamber without communicating with it, and which are open at their upper parts above the level of the sea. These pits are four in number. Two of them extend the whole length of the caisson parallel to its walls and 1 meter from the latter. They are 3 meters wide and 8.60 meters high. The two others, at right angles to the first, are placed symmetrical ly with respect to the shorter axis of the caisson. They are also 8.60 meters high, and their width is 3.50 meters. These four pits are connected, and the rectangular Port of Genoa. Fig. 157.— Great floating caisson used in laying the flooring of dock No. 2; transverse section. 0.70 meter; C, Shaft for the b£tou, 0.45 meter H. Ex. 410 — vol in — Face page 730. I srior diameter. CIVIL ENGINEERING,. ETC. 731 central portion formed by their interior walls communicates by a pipe with the sea. The walls and braces of the four pits form the framework to support the service bridges and stagings which lead to the different air locks, and carry the tracks, cranes, etc., required for the handling of the excavations and the materials. Arrangements have been made for filling the equilibrium cham- ber with water or compressed air, as may be necessary, and for changing, at will, the level of the water in the regulating pits, which may even be completely emptied by means of pumps. The appara- tus is thus maintained in equilibrium under all circumstances (Figs. 158-161). The caisson unloaded draws 2.55 meters, making the ceil- ing of the working chamber 0.55 meter below the level of the sea. It is brought into the condition of stability required for working, by placing enough iron ballast between the braces and over the ceiling, to make it sink 5.10 meters, which allows the ceiling of the upper chamber to be 10 centimeters out of water. The immersion will go on increasing as water enters the equilibrium chamber and into the regulating pits, unless compressed air is introduced into the working chamber. If one equilibrium chamber is filled with water, and if the central tank is maintained in communication with the sea by the pipe, of which we have heretofore spoken, the cutter may be lowered to the reference ( — 8) even if compressed air is introduced into he working chamber. We may then, if the working chamber remains filled with air, lower the cutter to the reference — 0, by allowing the water to rise 1.15 meters in the regulating pits: and to the reference —11.50 meters if the water level in these pits is brought to 2.50 meters below the sea, etc. To raise the caisson rapidly it is sufficient to pass compressed air from the working chamber into the equilibrium chamber and to diminish thus the load of water in the latter, taking care always to open the discharging orifices made in the walls of the pits so as to lower the level of the water which they contain as the caisson rises. But this process, which prevents access to the working chamber, is only applicable if we wish to obtain a rapid rise. If, on the con- trary, it is required to raise the caisson while the work is going on in the chamber we must empty first the regulating pits bv means of pumps and then begin by foiling out the water contained in the equilibrium chamber by means of compressed air. To facilitate these different operations several great pipes, fur- nished with stoppers, have been arranged in the equilibrium cham- ber above the braces. These allow the introduction of sea water or provide for its expulsion by conqu’essed air. The air from tin 1 working chamber is passed into the equilibrium chamber through a valve in a pipe which passes at the height of the service bridge- 732 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Port of Genoa. Positions of the caisson in its different states of eqcilibricu, scale 4 J 0 . Fig. 158.— Without ballast. 4 5 _ ___ — ■ —TX _ 1 -- ' r r- ■///’T-’ v//y/7 /?/ Fy/7//y/y »?///// 'i " ( air- convpr ^-5^, * ^ J v/ % rtf- " ’T^^TffTTi ^r. ■* •i!" oo Pigs. 160 and 161.— Caissons at work. y CIVIL ENGINEERING, ETC. 733 roadway. Another pipe allows air to be sent directly from the com- pressors into the equilibrium chamber. The regulating pits are put in communication with each other and with the sea by pipes 0.45 meter in diameter furnished with cocks operated on the service bridge. The weight of ballast and the dimensions of the pits depend on the depth at which the work goes on with a stable caisson. At Genoa the arrangements were made for a depth of from 8 to 14.50 meters. To be able to remove without too much difficulty the fragments of rock caught under the cutter a file of screw-jacks is arranged in the working chamber upon which, when necessary, the weight of the caisson may. rest. These jacks rest on two open beams fixed under the ceiling, parallel to the longitudinal walls which they must lift, and at 4 meters distance from them. The rock fragments are taken out by six excavation locks. The bdton is spread along the whole length of the flooring in superposed layers of 0.50 meter thickness. Little brick Avails are built as this goes on along the longitudinal borders of the mass, which prevent the bdton from running over. In the transverse direction, on the contrary, the bdton is left to take its natural slope. The walls would be useless there, besides breaking the homogeneity of the mass. (247) Mrthodof laying the flooring .— When the b£ ton has been spread over a thickness of 50 centimeters the caisson is vertically raised and a neAV layer placed above the preceding. When a first mass 1.50 me- ters thick has been thus deposited in three superposed layers, the apparatus is moved the whole of its width in the longitudinal direc- tion of the flooring, and grounded so that the longitudinal cutter shall come to rest at the foot of the cross slope of the first mass at S, (see Fig. 102). A layer of 50 centimeters is then deposited, the cais- son is then raised, and, by a slight longitudinal displacement in the contrary direction from the preceding, the cutter is brought to touch the slope of the first mass, no longer at its foot, but 50 centimeters abo\'e it (at the point 2). A second layer is then spread upon the first, taking care to fill up, above the cutter, the little triangular prism 50 centimeters high formed by the two transverse slopes, between Avliich the cutter is placed in its preceding position. The caisson is again raised 50 centimeters high, moved lengthwise, a third layer is spread, and at the same time the second little prism is filled up. We haA r e thus a second mass 1.50 meters thick joined to the first, and the caisson is then moA 7 ed to commence a third in the same man- ner. When the layer of 1.50 meters extends continuously the whole length of the flooring the same operations are gone through with, by successive displacements upon this bed. as were previously made on the rocky bottom. But care must be taken that the new positions of the caisson should not be directly over the preceding, in order to 734 UNIVERSAL EXPOSITION OF 1889 AT PARIS. have a series of little triangular transverse prisms to he filled up under the cutter, etc. We thus obtain a homogeneous and perfectly tight flooring. Fig. 162.— Method of laying the flooring of a basin. The numerals 1, 2, 8 , l 1 , 2 1 , 3 l , indicate the dif- ferent positions of the cutting edge of the caisson; the letters Si, S 2 , S 3 ; SV, S 1 *, represent the triangu- lar prisms of b£ton placed under water, corresponding to the respective positions of the cutting edge 2 , 3 ; 1 ', 2 ', 8 '. In order not to allow the caisson to he floating during these opera- tions it is supported upon two rows of jacks resting upon iron plates placed on the layer of bdton previously spread. (248) Supply of compressed air, etc . — The air-compressors, which supply the pneumatic apparatus above described, are placed 011 the Port op Genoa. Qcai des Graces. Quay wall in arcades. -=1 Fig. 163.— Longitudinal section of one of the centers. land, in a shop, by the side of the four 150 horse power engines which drive them. The supply pipes which lead to each caisson are placed on rafts. These pipes are made of sheet iron, with india rubber joints, so as to prevent rupture from their constant working due to the motion of the waves. CIVIL ENGINEERING, ETC. 735 The free air spaces are lighted by Gramme arc lights, and the cais- sons by incandescent lamps. The boilers are placed in the same shop as the compressors. A system of electric bells puts the caissons in communication with the engine shops, and informs the engineer of the quantity of air requisite, by which he regulates the working of tlxe compressors. (249) Centers of the arches for the Quai des Graces . — The spring- ing line of the arches between the piers of the Quai des Graces is at Fio. 164. — Details of the iron centers. Radius of the upper plate, R| =15.475 meters; radius of the lower plate, R 2 = 14.175 meters. the reference —0.20, and the construction of these arches required the use of quite solid centers, as the rise is reduced to 1.40 meters for a span of 12 meters. It was, therefore, very difficult to find a type of center which could be set up above the level of the water. In order to find a support it would have been necessary to go down 0 meters below this level. The contractor therefore decided to construct a special center adopted for these exceptional conditions. It is formed (Fig. 163) 736 UNIVERSAL EXPOSITION OF 1889 AT PARIS. of curved beams of 13.90 meters span, having their lower plates curved exactly to the form of the extrados of the arch to be con- structed, and they had to be arranged so as to coincide with this curve when placed. The lattice beams are arranged so that long bolts could be placed in line with the verticals, directed along the plain joints of the arch (Fig. 1G4), and having their heads borne by the upper plate on the beams. The nuts, screwed to the bases of these bolts, carried pairs of channel iron beams, laid along the gener- atrixes of the intrados of the arch so as to support the plates serving as bolsters. Upon these plates, suspended instead of supported, the arches were constructed. To remove the center, the bolts were taken away after unscrewing the nuts. The system of channel iron beams and intrados plates were then placed upon a raft, by which they were taken away to be set up again ; at the same time the lattice beams were removed by a floating crane and again placed between the piers, which had to be united with a new arch. Experience has shown this new arrangement of centers to have given, in all respects, satisfactory results. Chapter XXVIII. — Foundation of the jetties at La Pallice, the port of Rochelle. (250) The foundations of the two jetties in the outer harbor of La Pallice (Fig. 1G5) had to be laid below the level of the lowest tide. Fig. 165 —Port of Rochelle. Plan of the outer harbor of La Pallice. The specifications required them to be made of great blocks of ma- sonry, 20 meters long by 8 broad, separated by an interval of 2 me- ters and carried up to the level of 1.50 meters ; the choice of methods for carrying out the work was left entirely to the contractors. Above this series of blocks arose the body of the jetty, which was carried over the spaces between the blocks by little segmental arches of 3 meters span. The constructors, MM. Zschokke and Terrier, made use of mov- able caissons for the foundation of these blocks; the spaces between the blocks, which it was afterwards decided to fill up, was accom- plished by a special apparatus which will hereafter be described. \ » 737 CIVIL ENGINEERING, ETC. (251) Process adopted for the construction of the blocks. — As the blocks had to be built on the coast, without shelter against the sea, and especially against the southwest gales, the contractors could not employ the usual system of caissons, and build upon the interior flooring of the caisson, which the sea would have carried away and destroyed. They therefore made use of the movable caissons which they had successfully employed at St. Malo; by their use they were able to lay the foundations dry af sea, without leaving a particle of iron in the masonry; they were able to lay twenty-four monolithic submarine blocks with 1G0 meters of surface, amounting to 1,150 cubic meters each. (252) Description of the caissons and air locks. — Two similar iron caissons were built by MM. Baudet 1. Arnodin’s alternately twisted cable, one-third of the natural size. Consequently all the wires in the same cable, except the central one, have the same length, and when the cable is stretched all the wires are equally elongated. This is a property which belongs only to cables with straight wires, and to those which are alternately twisted. The tensions of the different wires produced by the elon- gation of cables twisted in the ordinary way, as in American cables have very different values. These cables manufactured by M. Ar- nodin may be called alternately twisted cables. The alternately twisted cables have a very much greater flexibility, which will be easily understood when we consider that the points of contact are fewer, and consequently the adhesion much less. The ratio of the hollow to the full portions is much greater than in the simply twisted cable; it varies from 0.15 to 0.30, according to the number of wires. Before the cable is manufactured the wires are passed through a bath. of inoxidizable composition; then, as each layer or crown is added, the cable passes anew through this bath, so that all the wires and all the layers are covered, and the interior spaces between tangent circumferences are filled with this composition. (270) The vertical suspension rods are the only ones which have parallel wires, in order not to complicate their attachment to the transverse beams and the parabolic cables. The old roadway weighed 1,354 kilograms per running meter, and would only allow the passage of two 5-ton carriages at a time. 752 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The new superstructure weighs 1,368 kilograms per running meter, and will permit two carriages of 7 tons to rest on the same cross beam. Hence, without altering sensibly the weight of the super- structure, which was a necessary condition on account of the state of the piers, they were able to obtain a much greater strength and stiffness in the new structure. . (271) Cost . — Suspension superstructure, etc., 264,976.70 francs ; administration expenses, demolition of the old superstructure, masonry, etc., 34,826.42 francs; total, 299,803.12 francs. The reconstruction of the superstructure was planned and carried out by M. Arnodin, under the supervision of M. Potel, chief engineer and Caparon, assistant. I am indebted to Mr. Arnodin for information and drawings. Chapter XXXI. — The lifting bridge at La Villette, Paris. (272) The port of Villette consists of two basins of unequal lengths (70 and 30 meters), separated by Crirnde street, which has a daily traffic amounting to four thousand vehicles. A channel 60 meters Lifting bridge at La Villette, Paris. Fig. 180.— Elevation. mm T i Am long and 11 meters wide connects these basins. This channel was widened to 15 meters, and a lifting bridge (Figs. 180 and 181) was erected over it. This bridge weighs 85 tons ; it is balanced by CIVIL ENGINEERING, ETC. 753 four counterpoises, one at each corner, descending into a dry masonry pit. The visible portion of the mechanism consists only of chains and guide pulleys with their supports, which are decorative cast-iron columns. The bridge being balanced, the only efforts to be overcome, both in ascent and descent, are those due to the friction and rigidity of the moving parts, which are estimated at about 5,000 kilograms. The moving mechanism consists of two cylinders placed under the abutments of the bridge, having their piston heads permanently at- tached to the superstructure. The necessary synchronism of motion in the pistons is accomplished by a shaft, with beveled wheels at each extremity, which in turn drives two transverse shafts provided with spur wheels gearing into racks placed on each upright post (Fig. 182). Fig. 181.— Transverse section. In order that the pressures under the pistons shall be exactly equal, two conduits are placed in the superstructure, which communicate with the interior of the piston rod, and empty, one above, and the other below the piston (Fig. 183). The lower surface of the piston is double the annular upper sur- face. When the pressure acts upon both faces the bridge rises; when the pressure acts only on the upper face, the lower being con- nected with the exhaust, the bridge descends; hence the whole valve work is reduced to a three-way cock (Fig. 184), connecting the bot- tom of the cylinder with the admission or the exhaust. H. Ex. 410 — vol ill 48 754 UNIVERSAL EXPOSITION OP 1889 AT PARIS. Lifting bridge at La Villette, Paris. Fig. 183.— Details of a press and the superstructure. CIVIL ENGINEERING, ETC. 755 To facilitate repairs, and to make up for a certain amount of play, tlie cylinders are suspended on trunnions, so as to oscillate length- wise of the bridge. The pistons being hinged to the superstructure the latter might move about the trunnions were it not maintained in its upright po- sition by guides. These guides consist of four tenons projecting from the ends of the beams into channels made for that purpose in the iron columns (Fig. 182). These tenons are united two and two at each end of the bridge by a very rigid piece to which the lifting chains are attached. Fio. 184.— Three-way cock for the lifting bridge at La Villette. (273) The roadway . — The stringers and crossbeams carry a wrought-iron paneling upon which is laid a mixture of sawdust and wooden splinters mixed with hot tar, and upon this mass, properly curved, a wooden pavement 0.10 meter high is placed’(Fig. 183). The intermediate mixture weighs about 1.000 kilograms and costs, when placed, 100 francs per cubic meter. Resistance and elasticity . — A trial panel with an intermediate thick- 756 UNIVERSAL EXPOSITION OF 1889 AT PARIS. ness of only 0.015 meter resisted satisfactorily a blow of 8 tons fall- ing from a height of 0.30 meter, there being no permanent change of form or rupture of the filling. The bridge is frequently operated by a child. Its complete lift is 4. GO meters, and the time of lifting 50 or GO seconds. The cost was 140,000 francs, not including the masonry. The bridge was built by M. L. Le Cliatelier, engineer, under the direction of M. Humblot, chief engineer. I am indebted to M. Chateliers article for the drawings and in- formation contained in this chapter.* A working model of this bridge was shown in the pavilion of the city of Paris. Chapter XXXII. — The Garabit Viaduct. (274) History. — M. Boyer, the engineer in charge of the prelimi- nary survey for locating the railroad between Marvejols and Neus- sargues, found that he could avoid constructing the road on the side of a very broken range of hills, and thus save a distance of 20 kilom- eters, by crossing the Truyfere at Garabit cut, where the valley nar- rows, being bordered on each side by elevated planes. The adoption of this line necessitated the construction of an im- mense viaduct 120 meters above the river. Under these circumstances M. Boyer applied to M. Eiffel asking him to prepare the preliminary plans and estimates for such a via- duct. similar to the one built across the Douro, at Oporto, eighteen months before. The reply of M. Eiffel showed that such an exceptional structure could be erected, which would be entirely satisfactory both as to its stability and its cost ; and that M. Boyer could thus adopt the new line on the plateau, cross the valley by a viaduct 122 meters above the stream, and still make a saving of three millions of francs over the road as originally projected, and at the same time have a much better working line. Under these circumstances the project for the viaduct furnished by M. Eiffel was approved, and he was authorized to construct it under the supervision of MM. Bauby and Lefranc, chief engineers, and MM. Boyer and Lamotte, assistant engineers. (275) Description . — The Garabit viaduct is built over the River Truyfere at Garabit, for the railroad from Marvejols to Neussargues. It crosses a deep valley and passes over an undulating plateau (Fig. 185). It carries a single line of rails. The iron portion has a total length of 448.30 meters, which is prolonged at its extremeties by masonry viaducts forming abutments. The rails are at a reference of 835.50 meters— that is to say, 122.20 meters above the deepest part of the valley. * Annales des Ponts et Chaussees, Sixth Series, Vol. 11. 758 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The iron viaduct (Fig. 185) is composed of straight girders resting upon masonry abutments at the ends, and upon intermediate wrought- iron piers on eacli side of the valley, and upon struts standing upon an iron arch of 165 meters span. We shall now give a description of these parts: (276) The horizontal superstructure is not continuous for its whole length, it is interrupted at the two struts upon the arch, and con- sist, properly speaking, of three consecutive portions. First. That on the Marvejols side, which extends from the Mar- vejols abutment to the first strut on the arch. Second. The central portion, which is included between the two struts. Third. The Neussargues portion, which extends from the second strut of the arch to the Neussargues abutment. The portion on the Marvejols side consists of five spans, as follows: Two end spans of 51.80 meters divided into fourteen panels of 3.70 meters each, giving a total length of 103.60 meters; three interme- diate spans of 55.50 meters, giving 166.50 meters ; finally a flush panel resting on the abutment having a width of 0.24 meter; total, 270.34 meters. The central portion consists of three equal spans of 24.64 meters, divided into six panels of 4.106 meters, and giving total length of 73.92 meters. Finally the girder on the Neussargues side has two equal spans of 51.80 meters forming fourteen panels of 3.70 meters, giving a total length of 103.60 meters, to which must be added the full panel upon the Neussargues abutment, 0.24 meter, making a total of 103.84 meters. The two end portions are fixed upon the great iron piers which form the abutments of the arch. They are able to expand freely on each side; and to allow for the motion produced by the variations of tem- perature there exists upon the abutments a play of 0.25 meter for the Marvejols portion, and 0.10 meter for the Neussargues portion between its ends and the stone guard, and a play of 0.10 meter between its extremity and the central portion on the struts. The central girder is fixed at the two middle points, and rests freely on the struts. (277) The roadway (Fig. 189) is placed 1.66 meters below the flange of the longitudinal girder, which thus forms a parapet of great stiffness. The girders are 5.16 meters high and 5 meters apart. The upper and lower members have the form of a f, and are united by a simple lattice and by vertical struts. Each of the members consists of a vertical web 600x15 and two horizontal angle irons and a uniform flange 500 X 10. Sup- plementary plates are added wherever the calculations require it, as CIVIL ENGINEERING, ETC. 759 shown on. the drawings. The lattice bars are T -shaped, and consist of a flange and two angle irons, and, in the central girder, simply of a web and two angle irons. The uprights have a double T section formed by two angle irons 80X80 10 and a web 8 millimeters thick. Above the supports, these uprights are replaced by a strong flush panel to guarantee the transmission of the efforts coming from the lattice bars. (The dimensions are usually given in millimeters). The transverse girders are attached to the longitudinal girders at the uprights of the panels. They have the form of a double T con- 70 X 70 sisting of a web 700x8 and four angle irons, — . This trans- verse girder is supported in the middle by two struts, each formed of two angle irons c< put together. These struts are attached to the feet of the uprights. They are united at their lower parts by a 80 x 80 tie rod formed of two angle irons — ^ . Finally, two bars simi- lar to the struts, which they cross at their middle point, are attached to the uprights below the transverse girder and to the center of the tie rod, thus forming, with the uprights, the transverse girder, the tie rods and the struts, a very stiff bracing (Figs. 189, B and C). The cross-girders are united to each other by five rows of longi- tudinal bearers. They consist, in the lateral girders, of a web 90 x 90 550x7 and four angle irons — , but in the central girder, where the span of the cross-girders is greater, the angle irons are — ^ , the web being the same. These bearers carry the metallic flooring, which is composed of iron plates 0.240X 120 and sufficiently strong to support the weight of a locomotive in case of derailment; also, the principal girders form a parapet strong enough to prevent the fall of the derailed engine. Besides this advantage, the flooring, which is almost continuous, presents a second, viz, that of forming an almost perfect wind- bracing to the girder at the level of the roadway. A lower wind-bracing, consisting of a single lattice in which each bar is formed of two angle irons , gives the two girders the greatest solidity to resist horizontal displacement. The girders rest upon hinged supports, some movable and others fixed. Each sup- port consists of an upper part of wrought-iron which is fixed under the flanges of the girders and which carries a slot in which is lodged a wedge to regulate the level of the superstructure. This wedge rests on a lower piece of cast-iron having a slot so arranged as to gear with that of the upper piece and prevent lateral motion. The lower 760 UNIVERSAL EXPOSITION OF 1889 AT PARIS, Garabit Viaduct. Central Portion. Fig. 186. Elevation. Fig. A. Sections k I, in n, o p, q r. s t, u v, Fig. 187. Wind bracing of the extrados between the bottom of the arch and the first strut. Fig. 188. Wind bracing on the iutrados between the two struts. CIVIL ENGINEERING, ETC. 761 piece has different forms according as the support is fixed or mova- ble. In the case of the movable support, this piece has a less height and rests on cast-iron rollers. These latter have the form of seg- ments which may be increased in number by bringing them nearer together. They rest upon a cast-iron plate. The use of hinged sup- ports has the advantage that the vertical reaction of the supports always passes through its axis, a condition of absolute necessity for iron piers of great height. (278) The arcli . — The great arch has a chord 1G5 meters long; its rise is 51.853 meters, and its height at the crown 10 meters. It consists of two lattice-work principals placed symmetrically with respect to the middle plane of the arch, but in oblique planes thereto. The planes of these principals, which are 20 meters apart at the origin, approach each other toward the crown, where the distance of separation is only 0.28 meters, measured at the extrados; hence the inward slope per meter is 0.11008 with respect to the vertical. This arrangement gives great stability to the arch, enabling it to resist the most violent winds. The principal ribs are cruciform in section; the mean fiber is a parabola. It has a great height at the crown, and terminates in a point at each springing line where it rests on the abutments by a knee joint. This form obviates the use of spandrels, the stresses of which are difficult to ascertain by cal- culation, and may vary considerably by expansions or the displace- ment of the rolling load, while their unusual dimensions would require an enormous amount of iron. The rigidity which this form gives to the principals enables them to resist, independently of all the accessory pieces, changes of form resulting from the unequal distribution of the loads ; and it has, besides, the advantage of avoiding all uncertainty as to the point in which the resultant of the forces strikes the abutment, since it can only be the point of contact of the pivot with the cushion stone, which remains the same whatever may be the alteration in form of the arch. The intrados and extrados members of each arched girder are connected by a lattice and by vertical struts, except in the panel next the springing lines, which is flush (PL IX). These members, with their open interior faces (Fig. 18G), consist of two webs 0.60 meters high, strengthened by two angle irons, and riveted to the flanges by four angle irons. The flanges themselves are formed of a variable number of plates 0.65 meter wide. The verticals and trellis work are of angle irons and flat bars (Fig. A). The principals are united by horizontal braces, each formed of four angle irons (70 millimeters) united by a plate iron trellis, except at the base, where there is a full web properly strengthened. Again, in the plane of each of these braces is a vertical wind bracing, each 762 UNIVERSAL EXPOSITION OF 1889 AT PARIS. bar having the section u' v', Fig. C, united by a trellis of flat bars, except at the lower panel which is flush. Finally the connection of the two arcs is completed, both at the intrados and the extrados, by bracing (Figs. 187 and 188), each brace consisting of a square box trellis formed of four angle irons with a double lattice of iron plate bars on their faces (PI. IX). (279) The iron piers are in the form of the frustrum of a pyramid, their edges or standards being girders properly braced (Fig. 18G). In the Douro bridge, built by the same constructor, the standards were box girders. In this case, for the faces of piers at right angles Fig. 189. Side elevation. Fife. C. Cross sections Fig. B. End elevation, o' p', s' t, u' v, q r, x' y’. to the roadway, which resist the force of the wind, the standards have a |J shape, in which horizontal and diagonal braces are in- serted, having the form of box trellis girders (PI. IX). This arrangement allows easy access and is capable of resisting compression as well as tension. (280) Principal dimensions . — The piers (Fig. 189) are of the fol- lowing heights, counting from the viaduct on the Marvejols side, measured from the masonry foundation, viz, 24.51. 36.46, 51.20, 60.73, and 60.73 meters. The batter in the piers 1, 2, 3 is 0.08272 per meter ; in Xos. 4 and t Paris Exposition of 1889— Vol. 3. Civil Enoineerino, etc. — PLATE IX. GARABIT VIADUCT. THE LOWER PORTION OF THE ARCH WITH ITS SUPPORTING PIER. CIVIL ENGINEERING, ETC. 763 5 it is 0.11088 in the plane of the great face. The transverse batters are 0.0386 and 0.0388, respectively. The piers are divided into panels 10 meters high, measured along the axis of the standard. Each pier terminates in a coping, which receives the supports of the superstructure. The piers, as well as the ai’ch, are anchored in the masonry, as shown in Fig. 186. In each pier a spiral staircase is placed, so that every part may be inspected. (281) Stresses . — The plans for the masonry work were wholly pre- pared by the Government engineers. The calculation of the stresses in the ironwork were made by M. Eilfel, and verified by M. Boyer by other methods and found correct. The sti*ess was to be limited to 6 kilograms per square millimeter under the combined action of the loads and the wind. The surcharge was to consist of a locomotive weighing 75 tons drawing a train of cars weighing 15 tons each. The effect of the wind was supposed to be 150 kilograms per square meter while the trains were running, and 270 while they were not, at which time the traffic would be suspended. In the calculation, the wind was supposed to act uniformly on the side towards it, and to act solely on the trellis bars on the opposite side. To this there was added its effect on the train, which, as the train is partly protected by the upper members of the girder, was estimated as acting on 1.6 square meters per running meter. This figure, 1.6, was adopted by M. Nordling in calculation of the great viaducts on the Orleans Railroad system, which were also constructed by M. Eiffel. The effects produced by the load and wind are such that the mem- bers of the arch may be regarded as bearing 2 kilograms per square millimeter under the ordinary load, 2 kilograms per square millime- ter from the effect of the surcharge alone, and 2 kilograms per square millimeter from the effect of the wind, so that the section of the members is one-lialf greater than it would be if the effect of the wind had been neglected. The influence of temperature is very slight when added to the loads. The maximum pressure at the crown of the arch under a variation of 30 degrees is only 0.63 kilogram per square millimeter. (282) Erection of the ironwork . — At the commencement of the work the country around the viaduct was a complete desert. It was necessary to begin by building offices and lodgings for the overseer, and for the engineers when they visited the grounds, storehouses for the materials, repair shops, lodgings for the workmen, stables for the horses, and also a school for the children of the workmen. On account of the difficulty of access M. Eiffel erected a service bridge on a level with the foundation of the chief pier, 33 meters above the stream. The head of this bridge was united with the na- tional highway by a road built on the side of the ravine. On this 704 UNIVERSAL EXPOSITION OF 1889 AT PARIS. roacl a storehouse was erected for the iron, with traveling cranes for unloading the wagons which brought it from Neussargues station. The platform of the bridge supported two lines of railroad, by which the materials were brought. All the foundations were laid on very resisting schist. The masonry constructions presented no difficulty. While the iron Gar abit Viaduct. Erection op the iron arch. a ‘5b a> PQ I s 2 £ piers were in process of erection two portions of the superstructure of the bridge were set up on the right and left banks. When all was ready these portions were pushed forward so as to overhang the central piers by a distance of 22.20 meters over the arched space. The end of each portion of the superstructure was made fast by twenty-eight steel cables to the masonry abutments of the accessory CIVIL ENGINEERING, ETC. 765 viaducts, and then preparations were made for raising tlie arcli by building two principal scaffoldings in front of the two foundations of the abutment piers up as high as the pivots. The upper parts of the scaffoldings were curved so as to form a center for the members of the intrados of panels 1 and 2, which were arched; then the outer extremity of this arch was held by twenty steel cables made fast to the overhanging superstructure (Fig. 190), and then they proceeded to erect the overhanging arch by attaching new pieces to those already riveted in place. When the overhanging portion erected balanced that of the lower part, whicli occurred at the fifth panel, a new set of cables uniting vertical strut 5 with the upper superstructure was put in, and the work was continued to strut 9 (Fig. 191). Again, twenty-four cables starting from struts 8 and 9 were made 766 UNIVERSAL EXPOSITION OF 1889 AT PARIS. fast to the superstructure, and the work so progressed until the crown was reached (see Plate X). The erection went on simulta- neously on each side. (283) Methods of raising the pieces . — The pieces were raised in two different ways; the heavy pieces were brought by cars on the service bridge exactly under their intended position. Rolling shears, placed on that portion of the arch already built, supported powerful winches which raised these heavy pieces (Fig. 190). For the light pieces, there were erected above the central piers two wooden stagings 10 meters high, which held a steel-wire cable tramway spanning the distance of 177 meters between the piers. The cable carried two cages, one for each side (Fig. 191). The cables were made with great care with a hemp core surrounded with eight strands, each of nineteen wires of 0.0024 meter in diameter. It withstood a tensile stress of 125 kilograms per square millimeter, and each wire could be bent double eight times before breaking. The diameter of the cable was 0.043 meter, and the weight, 6.5 kilograms per running meter. The rupture of one cable would have required an effort of 85 tons, and during the erection no cable had to bear a load exceeding 15 tons. (284) Proofs . — The proof load was made up of a train formed by a locomotive weighing 75 tons, drawing cars of 15 tons. The de- flection observed in spans loaded separately was from 0.016 to 0.019 meter. The arch loaded along its whole length by a train of 405 tons had a deflection of 0.008 meter. The same train occupying, successively, half the length of the arch gave a deflection of 0.010 meter. In the proofs for rolling load, the maximum deflection in the spans was from 0.015 to 0.018 meter, and that of the arch at the crown 0.012 meter. The horizontal displacement of the superstructure during the passage of a train was from 6 to 8 millimeters. After each proof the parts of the structure resumed their exact primitive position. (285) General information. Weight of the metal employed kilograms. . 3, 326, 414 Amount of masonry cubic meters. . 20,409 Cost: For the ironwork francs. . 2,350,000 For the masonry do.. . 850,000 Total do. ... 3, 200, 000 The works were begun in January, 1880, and terminated in Novem- ber, 1884. M. Eiffel was assisted by MM. Emile Nouguier, Maurice Koechlin, M. Compagnon, and M. J. B. Gobert. I am indebted to the Eiffel Co. for valuable information, plans, and drawings of this most interesting work. V Paris Exposition or 1889 -Vol. 3. Civil Engineering, etc. — Plate X GARABIT VIADUCT DURING THE PROCESS OF ERECTION. CIVIL ENGINEERING, ETC. Chapter XXXIII. — Gour-Noir Viaduct. 767 (286) The Gour-Noir Viaduct is situated on the railroad from Limoges to Brive nearUzerche, 4 kilometers beyond this last locality, where it crosses the river Vez&re at an angle of about 50 degrees. This river winds through a deep and very precipitous valley; sud- den freshets are frequent, and the direction of the current varies with the freshets. For this reason it was preferred to cross the river with an arch of great span, and as there was excellent building material in the vicinity this arch was projected with a span of GO meters. The work (Fig. 192) is built for two tracks and has a width of 8 meters between the parapets. Its total length is 108.46 meters. The radius of the intrados is 36 meters, that of the extrados 44- meters; the rise is 1G. 10 meters. The thickness of the arch at the keystone is 1.70 meters, at the springing lines 4.20 meters. The spandrels are open with six small arches with a span of 4.30 meters each. Idle wing walls are flush in elevation, but their filling is hol- lowed out in the interior by hidden arches of G meters span. Com- munication between these arches is made by openings 1.50 and 1.55 meters in diameter and with the outside by a manhole 0.80 meter in diameter. Between the spandrels and the wing walls are the buttresses, 2.85 meters wide at the top, which allows the establish- ment of refuges rendered necessary by the length of the work. In the part between the buttresses there is a parapet of open-work limestone, the only part of the work not of granite. To aug- ment the stability different batters were given to different parts of the construction. The mean pressure at the keystone is 16.60 kilo- grams per square centimeter, and the maximum pressure is 33.20 kilograms. On the ground under the foundation the pressure does not exceed 9.80 kilograms. The centers are made by seven trusses, 1.56 meters apart, each formed of a lattice beam 4.40 meters high, on which rests a system of pieces in the direction of the radii and having a fan-shaped ap- pearance. The rigidity of this fan is insured by two courses of bri- dle pieces. Each truss rests upon the lower support by means of interposed sand boxes. The lower supports, that is to say, all the parts below the sand boxes, are eleven in number, each one consist- ing of nine piles. From the nature of the river bed it was impossible to shoe the piles and drive them in the ordinary manner ; the piles were placed, and held by cement, in holes, some of which were bored out, and others hollowed out by stonecutters using steel drills under the shelter of cofferdams. Cost . — The cost of the viaduct was 235,202 francs. The projects were made and the works executed under the direction of M. Doniol, inspector-general. The engineers were M. Daigremont, chief engi- neer, and M. Draux, assistant. 768 UNIVERSAL EXPOSITION OF 1889 AT PARIS. CIVIL ENGINEERING, ETC. 76(4 Chapter XXXIV. — Viaduct over the river Tardes. (287) The viaduct on the railway from Montlugon to Eygurande crosses tlie Tardes near Evaux, and has an iron superstructure rest- ing on masonry supports. It consists of three spans, the middle one 100.05 meters, the two others are each GO. 45 meters (Figs. 103 and 104). The piers at the top are 4.50 by 8 meters. These dimensions in- crease from the top to the bottom. The pier on the left side is 50.05 meters high, that on the right* 48.02 meters. The abutments are 14.50 by 0.40 meters, with a hollow interior. The roadway consists of two great girders 8.30 meters high, with double lattice faces distant 5.50 meters from center to center. The track is placed above. The tops of the girders are 0.80 meter wide and form a sidewalk above the latter. The distance between the parapets is G.30 meters. The two girders are united by two courses of horizontal wind braces, one below and the other above, and by vertical struts. The rails are supported by wooden stringers resting upon stringers of iron united to the cross girders spaced 2.55 meters. The roadway is curved with a radius of 250 meters at the entrance and exit of the superstructure. A parabolic arc was intercalated between each curve and the right line portion of the middle structure. The rails are 91.33 meters above the valley. The piers are founded on compact granite rock and the abutments upon hard tuffa. (288) Cost . — The total expense was 1,400,000 francs, that is, 107 francs per superficial meter of the vertical projection. The pressure upon the masonry piers, including their own weight and that of the superstructure, with the proof loads, was 7 kilograms per square centimeter. It reached the figure of 9 kilograms by taking account of the moment of the wind against the roadway during the passage of a train extending along the whole length. The greatest stresses to which the iron is subjected under the dif- ferent proof loads and the effect of the wind are the following: G kilo- grams per square millimeter for the members of the girders, the cross-beams, and the sleepers under the rails ; 5 kilograms per square millimeter for the lattice, thehorizontal wind braces, and the vertical struts; and 4 kilograms per square millimeter for the rivets. Besides, the members of the lattice girders as well as the wind braces were strengthened, so that during the operation of launching the stress did not exceed at any point 8 kilograms per square milli- meter. The work was planned and carried out under the direction of M. Daigremont, chief engineer, and N. Guillaume, assistant. The contractor was M. Eiffel. H. Ex. 410— vol ill 49 770 UNIVERSAL EXPOSITION OF 1889 AT PARIS, KIos. 19.) and 194. — Elevation and plan of the Tardes viaduct. CIVIL ENGINEERING, ETC. 771 Chapter XXXV. — Consolidation of the side slopes at La Plante. (■-289) The railroad from Hopital-du-Grobois to Lods passes be- hind the town of Ornans in a deep cut through caving gravel. The cut was almost completely opened, when on account of the win- ter rains of 1882-’S3 they perceived a rising of the roadway amount- ing to 2 meters in height, combined with a general advancement of the upper slope without any change in its form. At the same time the bridge which crossed the cut (Fig. 195) was exposed to such a thrust that its keystone rose 0.21 meter and the upper abutment advanced 0.G4 meter, notwithstanding a strong bracing rapidly made to stay it against the lower abutment. Finally, openings in the hill at a distance of 90 meters from the crest of the cutting were observed, covering a space of about 3.30 hectars of ground. A num- ber of borings showed that the mass of gravel in which the cutting was opened rested upon stratified marl, but at the separation there was a thin layer of plastic clay very wet by the abundant exudation. The cutting having taken away the thrust of the hill, the latter slipped bodily upon the soapy layer of compressed clay, raising the soil of the roadway which was stopped by the opposite slope. To prevent this slipping the following means were employed: It was thought best to first divide the mass in motion into sections by the aid of fixed pillars. These piliars were made by great dry stone spurs of 2 meters thick, having a length proportioned to the im- portance of the mass in motion. These spurs rested on the side of the cutting upon great masses of masonry 5 meters thick and 3 meters wide, themselves buttressed against the lower wall of the cut by means of a reversed arch placed under the roadway. Al- though these constructions presented a great resistance against the motion, it was also advantageous to drain the water of exudation be- forehand, and to thus dry the mass immediately in front of the cut. These points being settled, it was only necessary to oppose the mo- tions of the intermediate masses placed between two consecutive spurs and partially drained by them. For that purpose a revetment was built formed of arches of 7-metA- span, the axis having an inclination of one-third to the vertical. These arches were 1 meter thick at the crown. They were supported by a rear wall having a uniform thickness of 3 meters. Finally, to catch all the exuda- tions which escaped from the spurs, these arches were covered with dry stone and all the water was collected in a drain which went from one end of the walls to the other. This last work had such dimen- sions that it could be inspected easily, and the satisfactory condition of the drainage could be told at each instant, by means of manholes. On account of the longitudinal undulations of the stratified marls on which the wall is founded, the rear wall of this last, which con- Flo, 1115. —Side slopes at La Plante after the completion of the work of eo 773 CIVIL ENGINEERING, ETC. tains the culvert, is more or less imbedded in this subjacent layer; hut at no point did the plane of slipping pass above the top of the arch in order to avoid crushing this work. It is understood that in the portions built into the stratified marl the thickness of the wall foundation is reduced as much as possible to allow the construction of the culvert. The drainage system worked perfectly, the amount of water caught amounted sometimes to 350 liters per minute, and went down to 10 liters in the season of great droughts. These different works were not carried out without great difficulty, and from the first great masses were obliged to be moved to erect in the middle of the slope a banquette of 2 meters. Since March, 1885, when the works wei'e finished, the motion has entirely ceased. The length of the cut consolidated is 416.77 meters; the surface in motion was about 3.30 hectares, and its mass attained 150,000 cubic meters. The total cost of consolidation amounted to 391,770.46 francs, which made the cost per running meter of the consolidation, 940 francs. The work was planned and carried out under the direction of Inspector-General Cabarrus by M. Chatel, chief engineer, and Bar- rand. assistant. Chapter XXXVI.— Tunnel through Cabkes Pass on the Rail- road from Crest to Aspres les Veynes. (•290) The prolongation of the Livron and Crest Railroad to Aspres les Veynes contains, at Cabres Pass, a tunnel 3,770 meters long. This important work is laid out in a right line 3,306.14 meters from the crest head; then it is prolonged with a curve of 800 meters radius for 393.44 meters, and terminates in a right line 70.42 meters long. It rises in an incline of 0.020 for 14 meters, of 0.015 for 472 meters, and of 0.009 for 2,358.77 meters to attain its summit at the altitude of 884.086 meters, whence it descends toward the station at Baume by a declivity of 0.003 for a distance of 925.23 meters. The Cabres Tunnel has been planned with two tracks, although the line has only one ; this arrangement was made tv facilitate ventilation, which a single-track section would not have been enough to guarantee ; it allows trains to cross, and diminishes the danger of a derailment in the middle of such a long tunnel. The tunnel is to be completely lined with masonry, varying from 0.50 to 0.80 meter, according to the nature of the strata. A flooring will extend through the whole length, and a central drain to collect the water. Refuge niches are established at distances of 50 meters in each wall, and a storage chamber is placed also at the middle of the tunnel. The most important point of beginning is the crest head ; on this side two 55 horse power steam engines are placed, which drive 774 UNIVERSAL EXPOSITION OF 1889 AT PARIS. •the air compressors to work the rock drills, the ventilators, and a gramme dynamo furnishing t lie electric lighting, for a part of the gallery and the works adjacent to the tunnel, during the night. The work of the drills produced a mean advancement of from 5 to 7 me- ters per day. Sometimes this advancement was stopped on account of explosive gas which was given off in great quantities and rendered Fio. 197. — Center used in Cnbres I’ass Tunnel. an exceptional ventilation indispensable. In view of preventing the danger, ventilation by suction was substituted for forced ventilation. Precautions were taken by the use of safety lamps, the explosion of the mines by electricity, the periodical examination of the air, etc. The suction produced by a conduit 0.50 meter in diameter and 2,000 Fig. 196. — Half sections of the C'abres Pass Tunnel. 775 CIVIL ENGINEERING, ETC. meters long having ceased to he sufficient, a vertical shaft was sunk 1,920 meters from the crest head. A natural current then established itself and carried away the explosive gas. If necessary, an exhaust- ing fan might be placed at the upper orifice to aid the natural draft. This tunnel was driven in the layers of marl belonging to the Ox- fordian strata, which swells and rises by contact with air, and requires a strong revetment. The contractors used for centers iron arcs, which had the advantage (Fig. 197) of occupying very small, space. (291) Cost . — The cost is estimated as follows: Francs. Driving the tunnel 3 , 770 , 000 Masonry 2,639,000 Total 6,409,000 That is, 1,700 francs per running meter. The works are executed by M. Pesselon, engineer, under the direc- tion of M. Berthet, chief engineer. Chapter XXXVII. — Cubzac Bridge over the Dordogne. (292) The railroad from Cavignac to Bordeaux crosses the Dor- dogne valley at 913 meters below the bridge constructed at Cubzac for the national roadway No. 10. The free height under the road- way was determined by the condition of putting no obstacle to the free passage of vessels going up to Libourne. This condition, to- gether with the configuration of the ground, required the construc- tion of great works extending over a length of more than 2 kilo- meters, consisting of : First. An iron viaduct on the right bank with a slope of 0.008 for a length of 294.58 meters. (Fig. 198 and 199). Second. An iron bridge of 5G1.60 meters over the Dordogne, in a straight line with the first. Third. Upon the left bank, which was flat and low, at 2 meters be- low the level of the highest waters, an iron viaduct 599.23 meters long, continued by a masonry viaduct 579.23 meters long. These two last works are on a curve 1,500 meters radius, and have a slope of one centimeter per meter. The viaduct of the right bank rests on masonry piers. It is formed of six spans of 44.98 meters each, with an upper roadway. The principal beams are diagonally braced with vertical uprights. The panels are3.4G meters span. The Dordogne bridge rests on iron piers and includes eight spans, the two end ones being of GO, and the six intermediate 73.60 meters long. Its principal beams have a double lattice web of 3.20 meters opening without uprights. The roadway is 26 meters above low wa- ter. The iron viaduct on the left side rests on masonry piers like those on the opposite bank. Its general aspect is the same, but on 17 6 UNIVERSAL EXPOSITION OF 1889 AT PARIS. account of the curvature, its thirteen spans of 44.98 meters are inde- pendent. The masonry viaduct consists of 40 arches of 12-meters span. It is g 3 J§ tc to a 5 o £ M a Ph s * 0 fc has a width of 8.40 meters at the springing lines, with an exterior hatter of 0.03 meter per meter carried to 0.05 meter for the but- tresses. CIVIL ENGINEERING, ETC. 777 (‘293) The Dordogne bridge rests on two abutment piers and on seven river piers. The calcareous marl rock on which its founda- tions rest in perfect security is 17.50 meters below low water. Com- pressed air was used in making the foundations ; the caissons of the Fig. 199.— Elevation of a pier of the viaduct of approach left bank). Fig. 200.— Elevation of an abutment of theCubzac bridge over the river Dodogne. abutments are rectangular with rounded angles. They were 17.00 meters long by 9.80 meters wide. (Fig. 200). The height of the working chamber was 2 meters ; its plate-iron ceiling, 6 millimeters thick, was sustained by lattice beams 0.97 me- 778 UNIVERSAL EXPOSITION OF 1889 AT PARIS. ter high, united to the caisson walls by vertical gussets terminated by struts, thus consolidating the iron plates. Heavy angle-iron beams, placed around the periphery, which were in turn strength- ened by outside plates 22 by 2 centimeters, stiffened the cutting edge. The sinking was accomplished by gradually lowering the air pres- sure when the pits had attained the required depth. All the piers rested on limestone except the fourth (the deepest), which descended 29.20 meters below high-water level into a layer of compact gravel. Under the pressure of three atmospheres, attained in the caisson in summer, the work became extremely difficult and even dangerous ; the lateral pressures were so intense that the pier. CIVIL ENGINEERING, ETC. 779 notwithstanding its weight, remained in equilibrium and could not descend more than 3 or 4 centimeters, even by suddenly lowering the air pressure. It was not therefore possible to go down 4 meters further to the rock under the gravel bank. The iron pier supports (Fig. 201) are anchored in the masonry by means of eight iron tie rods 0.10 meter in diameter, and four of 0.05 meters, bolted under a flooring of iron beams. The iron framework consists of six standards united by struts and braces and surmounted by a coping on which are placed the supports of the superstructure. The bridge is anchored upon the central pier and provided on the other piers with steel expansion trucks. The principal girders are braced at their upper parts by lattice girders 0.58 meter in height ; at their lower part by plate iron girders carrying the stringers. The horizontal wind bracing is obtained, below, by the plate-iron flooring riveted to the stringers and the cross girders; above, by lat- tice bracing. • (204) The launching was effected by means of rollers moved by levers, on each of the piers; but, on account of the great length of the bridge, this operation was divided into two parts, forming two fields of erection, one on the right bank and the other on the left. The same staging served for both halves of the roadway. The erection took place as the launching went forward, and the junction of the two halves was made on the central pier. The weight of each half of the superstructure was 1,700 tons, and its length 280 meters. The peculiarities worthy of notice in this operation are : The application of supporting rollers with double oscillation, di- viding equally the load on two rollers placed under the two webs of the double beams. The launching levers were moved by means of a steam engine set up on the superstructure for the last spans. Buffers, riveted upon the heads of the beams on the piers, were used to prevent the fall of the superstructure in launching, on ac- count of lateral displacement which might be occasioned by the winds or any other cause. The first two spans were launched by hand power. The launch- ing of the second required 120 men; the third and fourth would have required at least from 250 to 300 men. With the employment of such a great number of hands, separated from each other by a distance of 75 meters, the opei’ation could not have been made with perfect uniformity, and the total effort would have been far from corresponding to the sum of the partial efforts. To obviate this dif- ficulty the contractors substituted for the hand lovers a system of traction by a steam engine arranged so as to drive simultaneously all the levers requisite for the operation. 780 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (295) Apparatus with a universal joint, for launching by steam . — This system consists of an iron frame resting at its central part on a steel axle.* This axle allows the frame to oscillate, like a balance beam, lengthwise of the bridge. The frame itself carries at each end another frame, oscillating transversely and carrying independent rollers. The lower axle of the principal frame allows the system to tip longitudinally, and thus guarantees the constant contact of the two rollers on the same end with the bottom of the bridge. The transverse axles allow the transverse frame to tip in the case of a difference of level between the two members of the same gir- der, and thus equalize upon the four rollers the load supported by the apparatus. The rollers are 0. 50 meter in diameter. Each apparatus is calcu- lated to support 240 tons, that is, 60 on each roller. A rachet wheel is keyed to the shaft of each outer roller, and the rollers are moved by long levers turning freely on the shafts and carrying pawls. These levers are united transversely by braces, and longitudinally by jointed connecting rods to which bars and chains are attached. Each chain passes over a chain pulley at the over- hanging end of the bridge, and thence to the transverse shaft driven by the engine, whence it is wound on a drum placed in the rear. A friction coupling is placed on the motor shaft, to interrupt the forward motion of the levers and to regulate their return, which is done automatically by the action of counterpoises. Each of these counterpoises is formed of two weights suspended a certain distance from each other, so that both act at the beginning of the returning movement.; then, as the levers approach the vertical position, the resistance diminishing, the first counterpoise rests upon a platform, leaving the second to act alone until in its turn it ceases to act; the levers then having passed the vertical position, their own weight suffices to bring them back. A cord around a second drum, keyed to the same shaft as the first, holds a counterpoise, and thus tightens the chain after each oscillation of the levers. This system of launching by steam was perfectly satisfactory, giving a regular and gentle forward movement to a mass weighing 1,700 tons, at the rate of 6 inches per hour. Cost. — The total cost of these works amounted to 9,040,000 francs. The plans were made and the work carried out by MM. Prompt and Girard, engineers. The ironwork was constructed and the superstructure of the bridge launched by MM. Lebrun, Dayde' and Pi lid. * A horizontal bar rounded on the top. CIVIL EXGDTEERTXG, ETC. Chapter XXVIII.— The Crueize Viaduct. 781 (200) The Crueize Viaduct is situated on the line from Marvejols and Neussargues at the point where it crosses the river Crueize, 9' kilometers from Marvejols station.. It consists of six arches of 25 meters span and has a total length of 218.80 meters. The maximum height of the rails above the lowest point of the valley is 63.30 meters. It is founded on gneiss. It has two tracks, and its width is 8 meters between the parapets. At the right of the buttresses of the piers this width is 10 meters. The arches of the intrados consist of two quarters of circles having, respectively, 12.915 and 12.085 meters radii. This arrangement has for its object to give a slight slope, at the same time maintaining the level of the springing lines of the two adjacent arc-lies. This mode of obtaining the slope has the advantage of bringing the resultant of the pressures toward the center of the pier. The arches are 1.30 meters in thickness at the crown and 2.60 meters at the joints of rupture. The spandrils are lightened by three longitudinal archways of 1.20 meters span. The piers have on all sides a batter decreasing gradually from the base to the top. This equalizes the pressure upon the different courses, and leaves the edges continuous. At the same time, to facilitate the laying of the edge stones, a series of right lines 5 meters long, forming an inscribed polygon in the theoretical curve, is substituted for the curve itself, the curve corresponding to a constant pressure upon the different courses. This substitution is not observable in the work itself. The buttresses are placed against the piers and rise just to the top. They are 2 meters wide at the springing and project at the spandrel 1 meter at the level of the plinth. The maximum depth of the foundation is 10 meters and the mean depth 0.50 meters. The mean pressures per square centimeter of the different sections of the piers are from 8.20 to 10 kilograms. . The use of cut stone is limited to the coping. The centers were sustained by a double row of rails passing through the masonry piers. The first support, carrying the foot of the rafters, consisted of the two rails ; the second, placed 4 meters below, was formed of a single rail upon which rested, by an inter- vening plate, the braces sustaining the principal rafters. The cen- ters for raising were placed on the upper flooring of the service bridge used in erecting the piers. The total cost was 1,289,893.43 francs, whch gives per square meter of vertical projection in sight, the foundations not included, 105.80 francs. The engineers were M. Bauby, engineer in chief, and M. Boyer, assistant. 782 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Chapter XXXIX. — Construction of the Castelet, the An- toinette. AND THE LaVEUR BRIDGES. (297) These bridges have single arches of 41.20, 50, and Cl. 50 meters of span, respectively ; the first erected over the Aridge at Castelet, the second over the Agout near Vielmur. the third at Laveur. The adoption of a great arch, authorized for the three bridges by the incompressibility of the foundation, was justified at Castelet (Fig. 202) by the inclination of the line to the river and the violence of the rapids between the rocks, in a bed encumbered with blocks and with an indefinite depth. At Vielmur, 50 meters, by the depth of the river foundation, 8 meters, whifh made it economical to build a great arch, founded directly on the rock (Fig. 203). Finally at Laveur, Cl. 50 meters, where the foundations were facil- itated by the vicinity of a fine bridge of the eighteenth century (Fig. 204). Fig. 202. — Elevation of the Castelet bridge. The parapets, spandrels, and head bands have a batter of one- thirtieth for Castelet bridge and one twenty-fifth for the others. This has the advantage of decreasing the stress on the joints of rupture and of offering greater transverse resistance. In the spandrel of the great arch are smaller full-centered arches, of 4.50 meters span for the Laveur, and yf 4 meters for the others. This arrangement, pleasing in appearance when the openings are properly chosen, has succeeded perfectly, notwithstanding the theo- retical objection arising from the danger of distributing the loads in isolated zones, and the practical objection of the tendency to fis- sures produced near the springing lines. At Castelet and Antoinette the open viaducts continue to the ex- treme abutments; at Laveur they rest against two strong pilasters, which cast heavy shadows and stand out prominently from the neighboring portions of the work. This separation has been accen- tuated by lowering the level of the parapet above the 8-meter arches, and stopping the architrave and coping of the great arch at the pilasters. Fxo. 204.— Elevation of the Laveur bridge. ^nnrtionnnrimnnnniiiinnniinmnmir.TTinnmir.mifL^r^Jimaii: 784 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The extreme abutments are reduced by containing hollow wells. The principal dimensions of the great arches are as follows: Castelet. Antoinette. Laveur. Meters. Meters. Meters. Span 41.203 50 61.50 14 15.90 27 50 Kudins of the intrados above natural ground *22.20 +31 *31.20 Thickness of keystone 1.25 1.50 1.65 2. 283 2.25 2.81 Width: Between the parapets 5. 65 4.50 4. 50 0. 276 4.936 4.80 7.016 0.048 At the foundation 7.209 6.93 7.000 Ratio between the solid and hollow portions above ground 2.98 2. 18 1.95 Cu. meters. Cu. meters. Cu. meters., Masonry 1,547.28 2,403 6,618.67 Francs. Francs. Francs. Total cost 207,000 224,000 485,000 ♦On 130° 35' 15." t On 99° 42' 54 { On 148° 6' 54". (298) Centers — Bolsters and Sheathing . — A sheathing .025 meter thick, on which is drawn the position of all the voussoirs, is nailed upon the bolsters 10 by 14, spaced from the key to the springing line, from 25 to 50 centimeters for the Castelet; from 30 to 45 centi- meters for the Antoinette, and from 21 to 45 centimeters for the La- veur bridge. Trusses . — Each center consists of five trusses, the end ones being slightly heavier; each truss consists of two stories resting one on the other by means of nine files of sand boxes. The back pieces are triple in the Castelet (Fig. 205), double in the Antoinette (Fig. 206), and single in the Laveur bridge ^Fig. 207). They are supported by radial struts (except in the Antoinette bridge, where the river supports could not be numerous, the alternate struts are radial, and the intermediate ones are replaced by two) equally inclined to the soffit, forming a fan-shaped frame. At the Castelet and Antoinette bridges the fan (back pieces, struts, and the beam) rest directly on the sand boxes. At the Laveur bridge, on account of the height, another story has been introduced, consist- ing of vertical king-posts and diagonal-struts, forming a series of triangles whose vertices support the sticks of the fan. (299) Portion below the sand boxes . — At Castelet (Fig. 205) the upper portion is supported by two double rafters inclined to the hori- zon by the angles 43°, 19°, and 0° formed of pieces held by straps, and also by an iron tie rod. The lower rafters rest freely on sheets of lead laid upon oak sleepers built into a masonry apron. CIVIL ENGINEERING, ETC. 785 H. Ex. 410 — vol hi 50 .—Center for the Antoinette bridge. Elevation of a truss. Fio. 307.— Center for the bridge; elevation of a truss. Laveur bridge. Method op erecting the great arches. 788 UNIVERSAL EXPOSITION OF 1889 AT PARIS. At Laveur (Fig. 207) the center rests on nine supports, three of which are double, united by bridle pieces forming seven files of piles, two of which serve as wave breakers and wind braces. At Antoinette (Fig. 20G) there are only four supports, for, both of the centers resting on piles, the rocky bottom would not permit of their being driven in the usual way. Holes from 1.50 to 2 meters in depth were made in the bottom, slightly exceeding the diameter of the pile. The j>ile was cut off fiat and protected by sheet iron against crushing. The holes were cleared by divers, the piles lowered and held by cement, and when necessary by wooden wedges. This system, which was necessary on account of the nature of the bottom, was much more expensive than ordinary piling, but it was justified by the very slight settlement observed in the arch. (300) Construction of the arch — Castelet . — The arch was constructed of two rings (Fig. 207 A). The thickness of the first ring was, from GO to 40 degrees (maximum), 1 meter; from 40 to 20 degrees (mean), 0.75 meter; from 20 degrees to the keystone (minimum), 0.50 meter. Upon the heads only a single row of voussoirs was placed. The first ring was divided into six portions by wooden frames of two Laveur Bridge. — Supports for tiie voussoirs of the great arch during erection. kinds (Figs. 208 and 209), thus forming six great monolith vous- soirs, the joints of which were not keyed until the ring had been completed. The keyed joints were firmly calked with powdered mortar. The second ring was made in four portions, and there were for the two rings eight keyings. The arch was constructed in forty-two days of effective work. The settlements were, on the center, 53 millimeters ; on removing the center, sixty days after the second ring had been keyed, 2.02 millimeters. (301) For the Laveur bridge (Fig. 207 A).— The first ring was divided into fourteen portions or monoliths ; the second into six, and the third into four, having in all twenty-three keyings. The arch was constructed in eighty-two days of effective work. The settle- Fig. 208.— Support for the first ring. Fig. 209. — Support for the second and third rings. 789 CIVIL ENGINEERING, ETC. merits on the center were, on the downstream head 16.75 millime- ters, on the upstream head 20.07 millimeters, and after striking the center, one hundred and thirty days from the time the third ring was keyed, 0.62 millimeter. (302) For the Antoinette bridge . — In the first ring there were twelve monoliths ; in the second eight, and in the third four ; twenty- three keyings for the three rings. The arch was constructed in forty-four and one-half days of effect- ive work. The settlements were, on the center 0.13 meter, after striking the center, a few days after keying the third ring, 0.6 milli- meter. I am indebted to M. Sdjournde’s article (Annales des Ponts et Cliaussdes, sixth series, vol. 12) for the drawing of the centers, fig- ures 205-209, and information respecting the erection of the three bridges. Chapter XL. — The Ceret Bridge. (303) The Cdret bridge is situated near a city of the same name on the Tech. It consists of a great arch of 45 meters span connect- ing two viaducts. (Fig. 210). The adoption of a great arch, made possible by the solid ground on the banks, was justified by the necessity of avoiding the difficult and expensive foundations in the bed of a deep river exposed to heavy freshets. The spandrels of the great arch are hollow, consisting of a viaduct of full centered arches of 3 meters span, carried along to two strong pilasters which form prominent features of the bridge. They are still further marked by having a stone parapet above the great arch, while that above and beyond the pilasters is of cast iron. The spandrels and head band of the arch have a batter of -fa. The arch and pilasters rest on a projecting base capped with cut stone. The width of the bridge between the parapets is 4.62 meters, and the thickness of the great arch at the crown 1.40 meters. The head band is of hewn stones of large dimensions; the thick- ness of the voussoirs of the arch is about 0.42 meter. The stones of the head band and those of the soffit are in rustic work, projecting 0.10 meter from the spandrel. The head bands of the little arches are roughly dressed and flush with the spandrel face. The soffit is entirely of knotted ashlar, of the same width as the voussoirs of the head band, i. e., from 0.60 to 0.90 meter in depth and 0. 60 meter long. This is one of the characteristics of the arch. There is a hydraulic mortar capping 0.10 meter thick over the extrados, which is also covered with one of asphalt, with gargoyles for drainage. 790 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The filling consists of a layer of sand 0.10 meter thick covered with gravel. The plinth, 0.40 meter thick, projecting 0.45 meter from the face of the spandrels, is sustained by a series of modillions which requires an appreciable reduction in the width of the work under the plinth. Similarly the thickness of the parapet has been reduced to a mini- mum 0.20 meter above the grand arch. At intervals, pilasters reenforce the parapet. The stone is gi’anite; the greatest pressure is, at the keystone, 27 kilograms per square centimeter. On the foundation it is 14.20 kilograms. (304) Centers. — The center of the great arch consisted of four trusses 1.35 meters apart, formed of a fixed portion below the sand boxes, and a movable one above them. The fixed portion consisted of seven uprights supporting the sill, on which the boxes rested, and braced together with bridle pieces lengthwise and crosswise. Three of these uprights rested on framework supported by piles driven into the bed of the river. The pressures of the three others were borne by shores set at 45 degrees with the same support. The movable portion consisted of a series of back pieces resting on the uprights placed at the right of the sand boxes. Struts like the sticks of a fan resisted the flexure of the back pieces; a hori- zontal sill united the feet of all the uprights and 7’ested on the sand boxes. The bolsters were on the back pieces and a sheathing 0.025 meter thick covered them. The fourth back piece from the keystone placed below the general level of the sand boxes was supported by a secondary movable truss resting on two sand boxes corresponding to the angle u7° 30' from the point where the voussoirs began to rest on the center. The sand boxes rested on the sill by means of stringers. These boxes were protected from humidity by means of a pine box filled with plaster, the upper layer of which had been set. The uprights of the movable truss were bolted to the back pieces by means of iron gussets 0.003 meter thick. The center contained 362 cubic meters of wood; the iron weighed 5,482 kilograms. The cost was 41,635 francs. The great arch was built in its entire thickness up to the angle 67 degrees from the keystone. The first nine courses which did not rest on the center, were built with a templet, or form, upon which the position of each course was marked. Above the angle of 60 degrees the arch was erected in double rings, each in four blocks. The lowest block rested on three courses, having their joints filled with sheets of lead 0.02 meter thick and having a space of 0.10 meter between the edges of the sheets and those of the stones. The upper block was supported by joists uniting the triangular frames bolted upon the back pieces. CIVIL ENGINEERING, ETC. 791 The four blocks were built simultaneously. The key block was loaded to 22 degrees as soon as the block starting from GO degrees had attained 45 degrees. They keyed the joints at GO degrees, taking out as much as pos- sible of the lead. The empty joints were filled with cement mortar 792 UNIVERSAL EXPOSITION OF 1889 AT PARIS. nearly dry, and driven in with mallets; the thickness, on account of the pressure, being reduced from 0.02 to 0.01 meter. The second ring was also constructed in four blocks limited by the same angles as the first. The center was struck two months after the second ring had been keyed. There was no apparent motion of the arch. Cost . — The cost was 712,775.49 francs. The plans were made by M. Velzey, under the direction of M. Tastre, chief engineer. Chapter XLI. — The crossing of the Garonne at Marmande. — The use of masonry caissons. (305) The railroad from Marmande to Casteljaloux crosses the frequently submerged plain of the Garonne, for a length of 4,500 meters, which was covered in the flood of June, 1875, to a depth of from 2 to 4.50 meters. The plan (Fig. 211) shows the principal bed Fig. 211. — Plan of the submersible plain of the Garonne near Marmande. of the Garonne with the dikes. The dike on the left hand, which affects particularly the railroad, gives way ordinarily at A and at B. The breach at B does not give rise to strong currents, for the mass of water which fills the space above the railroad between the Ga- ronne and the lateral canal forms a buffer. On the contrary, the breach at A occasions strong currents which fall directly on the CIVIL ENGINEERING, ETC. 793 railroad. Great openings have been made for the disposal of this portion, amounting in all to 5,080 cubic meters ; the maximum dis- charge (freshet, 1875) was estimated at 10,000 cubic meters per second. iaduc 4 arches 25 ^ r iadufc 6 arches 25 ? In order to leave more free space under these works, for floating bodies, and to present to the flowing water, washing the side slopes, 794 UNIVERSAL EXPOSITION OF 1889 AT PARIS. a greater obstacle, the level of the rails has been raised in the part most exposed to the strong current, the force of the current dimin- ishing from the Garonne to the canal. The profile lengthwise is a series of piers united by slopes of 0.004 meters. The soil consists of 10 meters of alluvial deposit covering a very heavy compact clay marl (upper tertiary). The foundations of all the important works are built 1 meter at least into the marl; the Garonne bridge is built in 4 meters. Masonry work was built under the three highest piers of the longitudinal section, at slight expense. Iron was used under the lowest pier. The Garonne bridge consists of four 20-meter ellip- tic arches of 5 meters rise ; five elliptic arches of 56 meters span and 10 meters rise, sixteen 20-meter elliptic arches of 5 meters rise. The two viaducts at the end have arches of 25 meters span and 6.25 me- ters of rise, one of four, and the other of six arches. (Fig. 212). The two elliptic isolated arches are of 20 meters span and 5 meters rise. The two jron superstructures are 33 meters span. The foun- dations of the 36-meter arches were made by the use of compressed air, with iron caissons. The foundations of the 20-meter arches were made by the same system, part with ordinary iron working cham- bers, and part with masonry working chambers mounted on curbs. An abutment was founded upon a curb of a rectangular form, this form never having previously been employed. The curb was joined to the masonry by iron tie-rods 4.50 meters long imbedded in the masonry. For filling, bdton has given the best results; in every case the filling is terminated by pouring in cement. (306) The foundations of twenty such works were made by means of masonry working chambers, but of a form slightly different from those previously employed. (Figs. 213-219). First, the bases of all the foundations were elliptical. (Fig. 215). The base was somewhat strengthened. Second, the angle irons of the brackets were arranged with exte- rior wings, and the curbs were filled with brick masonry which gave them a great solidity. (Fig. 216). Third, the working chamber of an ogival form consists of cement masonry 1 meter thick. The method of making these twenty foun- dations was as follows : A pier of about 6 meters in height was constructed, including the exterior mastics, leaving the masonry and mastics to set for a month at least before sinking. (Fig. 217). They then proceeded to sink this first part. (Fig. 218). When this was at the bottom they constructed the rest of the masonry and waited a month again to make sure of the setting. They then began with compressed air. (Fig. 219). Only a single severe acci- dent Avas the sudden fall of 1.70 meters of the foundation in going through a layer of movable gravel. To prevent the recurrence of a similar fall during the period of work, they made, when traversing t 795 CIVIL ENGINEERING, ETC. dangerous layers, sudden changes of pressure every six hours. All the arches were constructed in rings, leaving the joint of rupture on the center (as these centers were very strong they did not key the joints of rupture until after the second ring had been finished). Masonry caissons used in constructing the foundations of the viaducts built to cross the SUBMERSIBLE PLAIN OF THE GARONNE. Figs. 213, 214, and 215.— Longitudinal and transverse sections, and plan of a pier with its masonry compressed air working chamber.; Fig. 216.— Detail of the cutting edge and wooden curb. Fig. 217.— Pier before sinking. Fio. 218.— Pier during the process of sinking. Fig. 219.— Pier completely sunk. The centers of the 20-meter arches were struck twenty days after they were keyed. Those of 3G meters, forty days after. (307) The cost of the substructure for the crossing of the Ga- ronne plain amounts to 3,895,950.21 francs for a length of 4,338 me- ters, i. e., 898,000 francs per kilometer. The inspectors-general were MM. Croizette-Desnovers, Vernis, De la Tournerie, and Renoust des Orgeries; the chief engineers, MM. Faraguet, Cliardard, Pugens, and Pettit; the engineers, Bernadeau, Sdjournd, and Guibert. 796 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Chapter XLII. — Oloron Bridge upon the Gave d’Oloron Railway from Pau to Oloron. (308) The bed of the Gave d’Oloron, at the point where it is crossed by the railroad from Pau to Oloron, is confined between two banks from 15 to 18 meters high and has a width which varies from 25 me- ters at low water to 52 meters in freshets. Freshets attain the height of 5.49 meters, with a velocity of 4.50 meters per second. The bottom of the bed is formed of schistose rocks mixed with banks of marl under a thin layer of sand and gravel. The difficulty of crossing the town of Oloron in a cut of 123,000 cubic meters, and of establishing a station of 8 hectares of surface at the end of the bridge, required that the rails should be placed 23.04 meters above low water. The marble quarries in the vicinity offered excellent ma- terials for the construction. These considerations led to the cross- ing of the river with a single arch of 40 meters span, which allowed the foundation of the supports to be made almost without a coffer- dam, in an impermeable soil. The total length, including the abut- ments, is 88.70 meters. The width between the parapets is 10 meters. The two abutments of the great arch are opened by full centered arches of 9.20 meters span. (Fig. 220). The head bands of the great arch have the same dimensions as the arch itself, 1.30 meters at the keystone and 2.60 meters at the joints at 30 degrees. The extrados curve is the arc of a circle determined by these three points. Its radius is 24.15 meters. The arch rests against two strong cut-stone pilasters, tangent to the intrados curve near the springing line. These pilasters project 0.30 meter from the surface of the spandrels under the plinth and have a batter of 0.05 per meter. The spandrels, on the contrary, are vertical and made of masonry, like the intrados and the surfaces of the abutments. To reenforce slightly the arch at the joint of rupture the extrados is limited by a tangent to the arc of a circle above defined, drawn at the extremity of the joint at 45 degrees. The mean pressure on the keystone is 11.31 kilograms per square centimeter. The mean pressure on the joint of rupture is 12.46 kilo- grams. A longitudinal arch of 1.50 meters, with two arches of 1.65 meters opening, sustained by pillars 0.90 meter wide at the springing lines, are placed above the spandrel of the arch. The maximum height of these pillars is 9.01 meters, and their thickness at the base 1.20 meters. They are united between them by two Stories of arches 0.50 meter wide. The end abutments are 15.30 meters high on the right bank and 11.50 meters on the left. The center of the great arch was built on two temporary masonry piers 2 meters thick. 25 meters apart, and upon two wooden piers placed against the abutment. The rapidity of the current and the The center consisted of five stiff trusses, 1.84 meters apart, and two head trusses situated at a distance from the first of 1.1< meters. This arrangement was required by the necessity of immediately con- CIVIL ENGINEERING, ETC. 797 rocky bottom would have rendered the establishment of intermedi- ate points of support difficult and costly. / 798 UNIVERSAL EXPOSITION OF 1839 AT PARIS. structing the portion of the arch next to the head band, on account of the upper voussoirs being single stones 1.30 meters long, while the body of the arch for a length of 8.30 meters was made in two rings, each having half the thickness of the arch. The center rested on sixty sand boxes, with cast-iron pistons. The center was set up by means of a very light temporary bridge upon the courses below the great bridle pieces. Up to the joints of 30 degrees the arch was constructed along its whole thickness, then the center was loaded with a weight equal to one-third of the weight of the first ring, which had a thickness of 1.30 meters at the 30-degree joints and 0.05 meter at the keystone. It was keyed in a single point at the crown. The second ring was constructed from the springing line and keyed like the first. The center was struck fifty-nine days after the second ring had been keyed. The settling was only 0.003 meter. The settlement on the center had been 0.03 meter. The total cost was 407,793.46 francs, that is, 4,579.17 per running meter. The Oloron bridge was projected and the work was executed under the direction of MM. Croizette-Desnoyers and Vernis, general in- spectors of roads and bridges, by M. Leraoyne, chief engineer, and La Riviere, Maurer, and Biraben, assistant engineers. Chapter XLIII. — The Gravona Bridge. (309) The Gravona bridge is situated on the railroad from Ajac- cio to Corte, about 15 kilometers from Ajaccio. The river Gravona, which takes its rise in the high mountains in the center of the island, is frequently exposed to freshets, which attain in this place, where the bed is particularly narrow, a maximum height of 9.53 meters. These special conditions require the avoidance of any obstacle what- ever to the current, and that the river shall be crossed without any support in its bed. The abundance of granite in the vicinity allowed the work to be built of masonry. It consists of a single circular arch. 43.53 meters span, 16.80 meters rise, and 22.50 meters radius. It is founded on the compact granite which comes down to the water’s edge. The bridge (Fig. 221) has a single track, and its width be- tween the parapets is 4.10 meters. The arch has a thickness of 1.40 meters at the keystone. The ra- dius of the extrados is 27 meters, and it has at the joint of rupture a thickness of 2.80 meters. It is covered with a layer of hydraulic mortar 0.10 meter thick. The spandrels are in a vertical plane ; they are prolonged back from the abutments to the natural soil by wing walls projecting 0.45 meter from the spandrel and having an exterior batter of 0.04 meter. The interior filling in this work between the spandrels is by means of stones carefully arranged by hand. The work is surmounted by 799 CIVIL ENGINEERING, ETC. a plinth 0.40 meter high and projecting 0.45 meter from the span- drel wall. This plinth is formed of two courses, and rests upon a series of biackets. On the plinth there is a full masonry parapet. The entire work is constructed of granite masonry from the neigh- boring quarries. The arch is of cut stone 1.40 meters thick at the keystone. The granite material used in the arch may be considered as resisting a load of 600 kilograms per square centimeter. The pressures are: at the key, 26.00 kilograms; at the joint of rupture, 31.80 kilograms; and upon the foundation, 14 kilograms. 800 ' UNIVERSAL EXPOSITION OF 1889 AT PARIS. The impossibility of establishing with security points of support in the river required the construction of a special kind of center. A provisional mass of masonry was therefore raised on each bank upon which was established the center supports, having a maximum span reduced to 29.63 meters. For raising the center a suspension bridge was employed made of two cables, whose extremities were made fast to solid frames embedded in a coffer covered with riprap. The transverse girders were formed of beams attached to the chain by ropes, and upon these beams a planking supported a light rail- road carrying the materials. Tlxe flooring of this bridge was 7 me- ters below the intrados at the key. The arch was constructed in two successive rings from the joint at 45 degrees, corresponding nearly with the angle of sliding. The termination of the arch was effected on the 1st of August, 1884. The center was struck almost automatically on account of the progressive contraction of the wood under the action of heat. The apparent elasticity of the arch at the moment of placing the keystone of the second course seemed to indicate that the center already had slightly settled from the arch. Thirty days after the keying the center had settled several centimeters. No settling took place in the arch. The cost was 119,000 francs, that is, 83 francs per square meter of elevation. The projects were prepared and the works executed under the direction of MM. Delestrac and Buffet, general inspectors, by MM. Gay, Dubois, and Margerid, chief engineers, and MM. Descubes and Fonan, assistants. PART I Y T — CIVIL CONSTRUCTION AND ARCHI- TECTURE. Chapter XLIV. — Specimens of iron construction in Paris. (310) The great retail store of M. Jaluzot, called Magazins du Printemps, destroyed by fire in 1881, lias been rebuilt by M. Sedille, architect, with the assistance of eminent engineers, both for the foundation and the iron framework. The ground has an area of 3,000 square meters, and it was re- quired to make an available floor space of 21,000 square meters and have the whole well lighted from the top and sides. These requirements precluded the use of walls, either within the building or on the outside. The floorings of the various stories, many of which were to hold heavy goods, were required to be especially strong, and the loads to be placed in the upper portions of the building made it necessary for the architect to adopt iron as the material for the construction of the pillars, and to employ stone simply for decorative purposes ; for ordinary hard stone supports a pressure of about 30 kilograms per square centimeter, while iron will support from 600 to 800. Now, the load on some of the pillars from 7 to 8 meters apart was 350,000 kilograms, which would have required stone pillars more than a meter square ; hence iron pillars were adopted. Again, the establishment of heavy piers on isolated spots required the foundations to be made by sinking pits in various parts of the ground ; but the soil consisted of fine sand mixed with water and clay. (311) Three borings, made to the depth of 35 meters, 96 meters, and 53 meters, respectively, produced a flow of 2,400 cubic meters of water per day. At a depth of 2 meters the soil was sand and gravel which showed a density sufficient to support a load of from 6 to 8 kilograms per square centimeter. It was therefore determined to sink cylindrical pits from 2.50 or 3 meters in diameter to the depth of 2 meters, the maximum load being 350,000 kilograms and the minimum 250,000. H. Ex. 410 — vol hi 51 801 802 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (312) It now remained to determine how these pits should be sunk. It would be dangerous to use the ordinary cofferdams from which the water is pumped out and bdton run in. Such a process, by re- moving the very abundant supply of surface water, would cause the settling of the surface sand, would break up the soil, and en- danger the foundations of the surrounding structures. For this Fig. 222.— Transverse section of the apparatus used for the pneumatic foundations. A, B, founda- tion caisson ; a plate-iron cylinder. C. D, E, F, movable plate-iron bell. G. H, plate-iron deck on which the excavation spoil is heaped to balance the under pressure within the caisson. K, entrance for workmen, and opening for the removal of the excavation spoil. L, air-lock door giving access to the caisson. M, inlet pipe for the compressed air. N, movable pipe for the introduction of the b6tou. reason the architect adopted the method of sinking them by com- pressed air, and employed this process for the first time in making foundations in the city of Paris. (313) M. Zscliokke, who has made a specialty of river and harbor work was called to make these foundations, which he did with great CIVIL ENGINEERING, ETC. 803 rapidity. For each foundation of a pier a cylindrical caisson AB (Fig. 222) was employed, from 2.50 to 3 meters in diameter and 2 meters high, made of plate iron 4 millimeters thick, strengthened above with two circular angle irons GO by GO, and at the lower part, by plate iron, 200 by 10 millimeters, forming the cutting edge. This caisson was to pass through the layer of water. It is surmounted by two conical frustrums, EF and GH, both of iron and united by an iron bell, CD, which is bolted to the upper belt of the caisson. These two upper cones, one interior, GH, inclined at 30 degrees, the other exterior, EF, at GO degrees, formed the air lock necessary for the process. They are each furnished with a door communicating with the interior of the lock at K, and from the interior of the lock to the interior of the caisson at L. Stopcocks serve to equalize the pres- sure between the two without being obliged to open the doors. At the upper part there is a winch to raise the buckets. An India rubber pipe 70 millimeters in diameter which passes through the two cones furnishes the compressed air. at 0.5 atmos- phere, from an air compressor. This air forces back the water and allows the workmen to work freely in the interior of the caisson which .slowly descends. The excavation spoil raised in the caisson is thrown out upon GH, and thus gives the caisson an increasing load necessary to balance the under pressure of the compressed air, beside the resistance due to the friction of the ground against the iron wall. Before running in the bdton the excavation spoil is thrown off, being compensated by the weight of the apparatus. The introduction of the beton is made through the movable tube X, fixed to the upper part of the cone EF, by means of successive lockages. As it is introduced it is well rammed, and when it arrives at the de- sired level for laying the stone blocks the supply of compressed air is kept up for several hours, to prevent the water from rising, and to allow the hydraulic mortar time to set. This done, it only remains to take away the double cone forming the air lock, and to remoA r e it to another caisson. Twenty-four hours suffice to make the complete foundation of a pit 2.50 meters in diameter; ten hours for sinking and excavating, and fourteen hours for running in and ramming the b^ton. Finally, to avoid the heating resulting from the compression of the air, a continuous jet of spray was introduced. These different operations terminated, the cones were taken away, leaving in the foundation the metallic caisson which enveloped the cylindrical col- umn of beton and added to its resistance. Thus the foundation of the forty-six iron pillars in the interior of the Printemps were laid. In like manner the stone pillars of the exterior facades, and the grand vestibule or hail were made. The loads which these foundations had to bear varied from 230 to 350 tons. For this reason, at certain points heavily loaded, the 804 UNIVERSAL EXPOSITION OF 1889 AT PARIS. diameter of the foundation was made 3 meters instead of 2.50, the diameter adopted for most of the other caissons. (414) I ' ounclations for the steam engines . — The use of dynamo- electric machines for lighting the new edifice recpiires a Corliss steam engine of 500 horse power, and it was necessary to take special pre- cautions in making the foundations for it. Accordingly, the archi- tect decided on the construction of an iron caisson 12.75 meters long, 4 meters wide, 2 meters high, and 0.006 meter thick, to lay the foun- dations below the sheet of water by means of compressed air. This was successfully accomplished and filled with a mass of Mton 1.20 meters high. On this mass stones of enormous size were placed to receive the supports for the four principal shafts. (315) Iron work . — What was required in the new store was space and light. By increasing the number of stories upon the ground of 3,000 meters, an area of 21,000 meters of flooring was easily obtained. Transverse sections of the pillars of the Magazin dp Printemps. w - - 5 oo *. '•< • _ Soo X 1 r T ; r M Son (2 ,c5 - to A r 1 r "> USojiK L. -j L -U L J r L Fig. 223.— Exterior. I. Least loaded. Fig. 224.— Interior. II. Least loaded Fig. 225.— Interior. III. Most loaded. As to the light, it had to be obtained through the sides, and through the glazed roof of the central nave. Consequently there must be no interior wall and no exterior wall around the edifice, but simply isolated iron pillars of as small a number as possible. (316) The contract for the iron work of this important construction was given to Baudet, Donon & Co., whose reputation and great workshops were a guarantee of rapid construction. To determine the resistance of these pillars the section of which was fixed at 50 centimeters on each side, in order to leave the necessary spaces for the conduits, it was necessary to take account of the "exact loads Paris Exposition op 1889— Vol. 3. Civil Engineering, etc.— PLATE XI. f IRON FRAME WORK OF A PARIS STORE (THE MAGAZIN DU PRINTEMPS). 805 CIVIL ENGINEERING, ETC. whicli the pillars would have to support. These loads are of two hinds, the dead load and the rolling or accidental load. The dead load is composed of the weight of all the parts of the construction which form the flooring. The multiplicity of stories of small heights rendered it important to diminish as much as possible the thickness of the flooring. The architect obtained this result by using for floor timbers the smallest specimen of double T-iron girders in use. that is to say, T of 80 millimeters, with a span not exceeding 2 The hllm g was fOT med of hollow brick laid in plaster upon iron beams 14 millimeters thick. For the calculations, the dead load upon the flooring was estimated at 280 kilograms per square meter; the accidental, or live load, at 520 kilograms. The loads on the different floorings being thus determined, the sections of the pillars were calculated by considering them as built in at each story, on account of the beams being strongly fastened to their brackets. The loads may be thus described: First. Upper flooring of the cellar Second. Of the ground floor Third. Mezzanine story Fourth. First story Fifth. Second story Sixth. Third story Seventh. Flooring above the third story. Eighth. Roof truss Ninth. Pillars, etc Total per square meter Kilograms. ... 1,200 . . . 800 . . . 800 . . . 800 . . . 800 ... 800 . . . 500 . . . 300 , . . 600 6,600 (31 7) These pillars, loaded according to their position, may be divided into three classes: first. Pillar on the perimeter (Fig. 223). Second. Pillar on the interior least loaded (Fig 224). Third. Pillar on the interior most loaded (Fig. 225). I. Surface to be carried, 7.80 by 3.20 165,000 kilograms. Web 450 by 12 4 plates 500 by 12 4 Angle irons, 100 and 100, by 12. . 4 Angle irons, 80 and 80, by 10. . . . Total Load per square millimeter 45400 meters, = 25 square meters. 25 by 6,600 = square milimeters. . 5,400 do 24,000 do ... 9,600 do 6,400 45,400 3.6 kilograms to resist crushing. II. For an interior pillar least loaded ~~ 230000 57400 3.87 kilograms. III. For the most heavilv loaded 348000 90400 3.85 kilograms. For the short double T beams It (load per square millimeter) = 6.3 kilograms. For the longest beams R (load per square millimeter) = 6.7 kilograms. 806 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Strength of the pillars to resist rupture hy flexure for cases I, II, and III, calling the height of the pillar in the cellar 3 meters, and its width 0.5, we have hy Love’s formula, 1.55+0.0005 hence, I. R = 3.6 by 1.568 = 5.75 kilograms per square millimeter. II. R = 3.87 by 1.568 = 6.07 kilograms per square millimeter. III. R - 3.85 by 1.568 = 6.03 kilograms per square millimeter. 1.568; PI. XI shows the frame work in construction, and exhibits the form and arrangement of the pillars and floor beams. Acknowledgment . — I wish to express my indebtedness to Messrs. Sedilffi and Baudot for explanations and documents. Chapter XLV. — The Eiffel Tower. (318) The investigations of M. Eiffel upon high iron piers for railroad viaducts like that at Garabit, led him to consider that such piers might be erected to a height very much greater than they had yet attained. The principal difficulty hitherto found in the erection of high iron piers is, that, generally, a system of heavy lattice bracing is placed on their faces to resist the action of the wind; as the pier is in- creased in height the base also increases, and this lattice bracing, on account of its great length, becomes of imaginary rather than real utility. There is, therefore, great advantage in dispensing entirely with these large and heavy accessory pieces, and giving to the pier such a form that all the shearing stresses shall be concentrated in its edges, these being reduced to four great columns united simply by widely separated horizontal bands. Imbued with these ideas, M. Eiffel made the calculations for a great pier 120 meters high and 40 broad at the base. These researches finally led to the studies for a tower attaining a height of 300 meters. The project for such a tower was carefully prepared by MM. Nou- guier and Koechlin, engineers of the Eiffel Company, and M. Sau- vestre, architect. It was brought before the French Society of Civil Engineers by M. Eiffel, and thus summarily described. (319) Description of the proposed tower . — The frame work con- sists essentially of four uprights, forming the edges of a pyramid with curved faces; each upright has a square section decreasing from the base to the top, and forms a curved lattice caisson 15 meters square at the base and 5 at the top. The uprights are 100 meters apart from center to center at the base, and are firmly anchored in a solid mass of masonry. At the first story, 70 meters above the ground, the uprights are united by a gallery 15 meters wide running from pier to pier around the whole construction, and having an area of 4,200 square meters. o> 3 o — i- c cc © ir. - c * K ffi CIVIL ENGINEERING, ETC. 807 At the second story there is a platform 30 meters square. At top, a cupola, and a balcony with an area of 250 square meters. At the lower part of the tower an imposing arch of 80 meters span and 50 rise is placed in each face, which, by its broad open-work head band and its ornamented and variously colored spandrel, forms the principal decorative feature. (320) Strength and stability of the tower ; force of the wind. — The force or pressure of the wind may be decomposed as follows : Suppose for an instant that we have in one face of a pier (Fig. 226) a simple lattice forming a surface resisting the shearing stresses of the wind ; let the horizontal components of these stresses be P 1 , P“ P m , P ,v . To calculate the stress in the three pieces cut by any plane M N, it is sufficient to determine the resultant P of all the exterior forces acting above this section, and to decompose this resultant into three forces passing through the pieces cut. If the form of this system is such that for each horizonal section M X, the two uprights Oa and Ob intersect on P, the effort on the lattice bar C D is nothing, and it may be dispensed with. The ap- plication of this principle constitutes one of the peculiarities of M. Eiffel’s system. It is therefore evident that the direction of each element of the uprights follows the direction of a curve traced upon the chart (Fig. 227), and in reality this exterior curve of the tower is no other than the curve of the moments of flexure due to the wind. (321) Hypotheses in reference to the pressure of the wind. — The uncertainty of the effects of the wind, and the data to be adopted both as to the intensity and the amount of surface struck, requires the adoption of particularly prudent hypotheses. With regard to the intensity of the pressure of the wind two sup- positions have been made. The first assumed the wind to act on the tower with a constant pressure of 300 kilograms per square meter; the second, that the intensity increased uniformly from 200 kilograms at the base to 400 at the top. (322) As to the surface struck, it was assumed, notwithstanding its apparent exaggeration, that the upper half of the tower should be treated as if the lattice work were replaced by closed surfaces; that upon the intermediate part, where the open spaces are much greater, each anterior face should be reckoned four times the real surface of the iron; below (the gallery of the first story and the upper por- tions of the arches) the anterior surfaces shoidd be counted full ; finally, at the base of the tower, the uprights should be counted as full and struck with twice the force of the wind. These hypotheses are moi’e unfavorable than those usually adopted for viaducts. With these surfaces the calculations have been made under both 808 UNIVERSAL EXPOSITION OF 1889 AT PARIS. hypotheses of the intensity of the wind, and the results given in the annexed chart (Fig. 227) show that the two funicular polygons thus obtained are nearly identical. In the hypotheses of the uniform wind of 300 kilograms per square meter upon the whole tower, the horizontal effort upon the whole construction is 3,284 tons, and its point of application is situated 92. 30 meters above the masonry base. The overturning moment is M,= 3,284 X 92.30 = 303,150 ton-meters. (323) As to the moment of stability, the weight of the construc- tion is as follows: Tons. Metal „ 4,800 Rubble flooring 1,650 Sundries 50 Total 6, 500 The base of the tower being 100 meters, the moment of stability M s = 0,500 x ' = 325,000 ton-meters, which is greater than M,. (324) In the second hypotheses, i. e., the wind varying in intensity from 200 to 400 kilograms per square meter, the total horizontal effort is only 2,874.4 tons, hut its point of application rises to 107 meters above the masonry base. The overturning moment in this case is M., — 2,874.4 x 107 = 307,502 ton-meters. This is very nearly the same as M„ and is still below M s . (325) Anchorage . — The stability is still further augmented by anchoring each of the four standards of an upright to the massive base by means of iron ties embedded in a mass of masonry sufficient to double the coefficient of safety. (Figs. 232 and 233). (320) Deflection . — If we take Claudel’s designation of winds given below, the calculated deflection will be as follows : Designation of the wind. Velocity per second. Pressure per square meter. Deflection. Meters. Kilos. Meters. Very strong breeze ... 10 13.54 0.038 Reefing breeze 13 19.50 .055 Very strong wind 15 30.47 .086 Gale 30 54.16 .153 Hurricane 34 78.00 .221 (327) Resistance of the tower against the wind . — First case, wind 300 kilograms pressure from base to top. Second case, wind increas- ing uniformly from 200 at the base to 400 at the top. CIVIL ENGINEERING, ETC. 809 Corresponding surf aces and pressures. No. of the ele- ments. Height of the ele- ments of surface. Surface of the ele- ments. First case of the wind. Second case of the wind. Pressure per square meter. Total pressure. Pressure per square meter. Total pressure. Top. Meters. Sq. meter. Kilos. Kilos. Kilos. Kilos. 1 76.0 950 300 285.000 375 356,250 2 64.5 1,004 300 319,21X1 328 348, 992 3 18.5 583 300 174.900 300 174.900 4 11.5 391 300 117, 300 290 113,390 5 39.0 1,230 300 870, 800 274 338,004 6 7.0 300 300 108,000 258 92, 880 7 42.0 3,003 300 900.900 242 720,726 8 41.5 3,301 300 1,008.300 215 722,015 300.0 3.284,400 2,874.417 (328) Determination of the stresses in the uprights . — The prolon- gation of the section A B meets the axis at O, the point of application of the resultant of the forces 1, 2, 3, 4, 5. We may therefore decom- pose this force of 1,267,200 kilograms in the direction of the uprights, which gives for each of them a stress of >(>< ■ kilograms. The stress in the lower part of the uprights is -~* 2 3 * * * * * * * ll ' ) " >l>l> kilograms. The stress in the upper part of the uprights is — (> * ><)(H I kilograms. /v (320) Calculation of the section of the base of the uprights . — Total weight on the foundations, 0,500,000* kilograms. Overturning mo- ment, 303,150,120. Load on the base of an upright from its own weight — 6,500,000 4 1,625,000 kilograms. Load on the base of an upright due to the effect of the wind — 303,150.120 = 1,515,750. 2 by 100 Total loads, 3,140,750 kilograms. Section of a standard at its base, 80,148 square millimeters. Section of an upright = 80.148 by 4 = 320,502 square millimeters. 3 140 *50 Load per square millimeter = f f = 0.8 kilograms per square Ot/v millimeter. M, = 303.150,120 the overturning moment, first case. M„ = 307,562,619 the overturning moment, second case. CONSTRUCTION OF THE EIFFEL TOWER. (330) The idea of a tower 30o meters high is not a new one. In 1833 the celebrated English engineer Trevithick proposed to erect a *Tliis refers to the first project ; the weight of the metal in the actual structure is 7,300,000. 810 UNIVERSAL EXPOSITION OF 1889 AT PARIS. < t-ii on tower 1,000 feet high, 100 feet in diameter at the base, ancl 12 feet at the top. But this work was never begun. On the occasion of the Centennial celebration in 1876 Messrs. Clarke, Reeves & Co. proposed to construct at Philadelphia a wrought-iron tower 1,000 feet high, and 150 feet at the base. In 1881 M. Sebillot proposed the erection of a tower 300 meters high to hyht I aris electrically, but this plan was never adopted. (331) Situation .— It was finally decided that the tower should be built on the Champs de Mars in front of the Jena bridge, M. Eiffel receiving a subsidy of 1,500,000 francs and the tower to revert to the city of Paris after a lapse of twenty years, M. Eiffel and his rep- resentatives having the income derived from the tower up to that date. Fig. m— General plan of the foundations of the Eiffel tower. (332) Foundations . — The base of the tower consists of four piers which bear the names of the four cardinal points, the two next the Seine being the north and west, the others being east and south. It was absolutely essential that the piers should be erected on firm ground and so careful soundings were made to determine its nature. (333) Soundings. — A great number of borings in the Champs de Mars showed the strata to be arranged as shown in Fig. 229, that is, the lower layer consists of a bed of plastic clay resting on the chalk formation and capable of supporting 3 to 4 kilograms per square centimeter. I his clay bed slopes slightly from the Ecole Militaire toward the Seine, and underlies a bank of compact sand and gravel, a good ma- terial for foundations. CIVIL ENGINEERING, ETC. 811 Fig. 228 shows the general plan of the foundations. For the two piers, No. 2 and 3, the made ground was 7 meters above the level of the Seine, and below that level there Avas a bed of gravel G meters thick affording favorable conditions for an excellent foundation ; the piers were accordingly built upon a layer of cement concrete 2 me- ters thick. (Fig. 232 and Plate XIII). Sandy clay. Limestone. Made grouDd. Sand and gravel. Plastic clay. Fig. 220.— Longitudinal section of the Champ de Mars through the axes of piers 1 and 2. (334) Use of compressed air . — The other two piers, Nos. 1 and 4, were differently founded. The bed of sand and gravel occurred at the level 22 (above sea level), that is, 5 meters below the level of the Seine (27), and it was overlaid by soft alluvial deposits from the river. Fig. 230.— Longitudinal and transverse sections of the iron caissons. In order to make sure, a preliminary bell or caisson 1.50 meters in diameter (Fig. 222) was sunk in the center of each pier, and it was ascertained that, below the sand and gravel, sand, ferruginous sandstone, and a bank of chloride of calcium were found at the bot- tom of a depression washed out of the plastic clay. There was no difficulty, therefore, in making the foundations by using compressed air with four iron caissons 15 meters long and 6 812 UNIVERSAL EXPOSITION OF 1889 AT PARIS. mmmm ip v*^: •.^•5Vr. v J | ■ ! m/m mm. mmm}, v/Mv\ Eiffel Tower. Fig. 231.— View of a caisson for making the foundations of the Eiffel Tower by means of com- pressed air. Section showing the underground work and the shafts for the men and the materia's. ■MB' Paris Exposition of 1889— Vol. 3. Civil Engineering, etc.— PLATE XII. THE EIFFEL TOWER. IRON CAISSONS USEO WITH COMPRESSED AIR IN BUILDING THE FOUNDATIONS OF A PIER. CIVIL ENGINEERING, ETC. 813 meters vide for each pier, and sunk 5 meters below the level of the river. Figs. 230 and 231 show the arrangement and dimensions of one of these caissons, and Plate XII shows all four caissons of one of the piers, in the process of sinking. (335) Description of the ironwork . — Each of the four uprights of the tower is a huge frame 15 meters square whose edges transmit the pressure to the ground by masses of masonry placed under each; there are four of these masses for each pier. The top of each of the masses, which takes the thrust, is at right angles to the direc- tion of the edges of the upright; the mass itself is pyramidal in form, having its vertical face in front and its oblique face behind. Its dimensions are so calculated as to bring the resultant of the oblique pressures to a point very near the center of the foundation. This oblique pressure amounts to 565 tons without that of the wind, and 875 with that of the wind. (336) Details of the foundation . — Upon the bottom of piers Xos. 1 and -1, i. e., at a depth of 14 meters, the vertical pressure is 3,320 tons with the wind ; this, spread over a surface of 90 square meters, gives a load of 3.7 kilograms per square centimeter. Upon piers 2 and 3 the pressure on the ground at a depth of 9 me- ters is 1,970 tons, which, spread over a surface of 60 square meters, gives a pressure of 3.3 kilograms per square centimeter. The masses of concrete are 10 meters long by 6 meters wide, ar- ranged as in Fig. 232. The concrete is made of 250 kilograms of Boulogne cement for each cubic meter of sand. The masonry is of Souppes stone set in the sand cement. The use of cement was requisite for attaining a rapid setting, thus avoiding any settling. At the center of each mass two great anchor bolts 7.80 meters long and 0.10 meter in diameter are imbedded, which, by means of two iron I bars and anchorage plates, hold on to the principal portion of the masonry (Fig. 233). This anchorage, not necessary for the stability of the tower, which is maintained by its own weight, gives an excess of security against overturning, and, moreover, it was utilized in the erection of the oblique standards. The masonry, subjected to a load of from 4 to 5 kilograms per square millimeter, is capped by two courses of cut stone from Chateau Landon, having a resistance of 1,235 kilograms per square centime- ter. The pressure under the iron shoes is not more than 30 kilo- grams per square centimeter, hence the coefficient of safety is 40. It may be seen from these figures, and from the materials selected, that the foundations have been so laid that there can be no doubt as to their perfect security. Besides the separate foundations for each standard there is a ma- 814 UNIVERSAL EXPOSITION OF 1889 AT PARIS. sonry base, carrying no load, but designed to support the metal moldings which decorate the pedestal of the uprights. The walls which carry this pedestal are laid on arches and form a square 26 meters on a side, the whole of the substructure being tilled with earth except those piers in which chambers are reserved for the elevator engines and boilers (PI. XIII). (337) The two lightning conductors for each pier are carried down in cast-iron pipes 0.50 meter in diameter and 18 meters long, which V Fig. 232.— Plan, and section along A B, of pier No. 1. are sunk below the water-bearing stratum and are in direct com- munication with the ironwork of the tower. (338) The hydraulic jack of 800 tons . — Before describing the erec- tion of the tower it may not be oiit of place to give an account of the powerful hydraulic jack used to adjust the heavy standards. To be perfectly sure that the four supports of the tower shall be in exactly the same horizontal plane, a space has been provided un- der each of the shoes of a standard in which a hydraulic jack of 800 tons power could be placed so as to raise or lower any upright in the THE EIFFEL TOWER. VIEW OF A PIER WITH ITS INCLOSING WALL. CIVIL ENGINEERING, ETC. 815 structure for the insertion of steel strips or wedges between the bed- plate and the shoe. Figure 237 shows the jack in section, and fig- ure 238 taken from La Nature, shows it in operation. The cyl- Fig. 233.— Anchorage of the foundations. Details: showing one of the cylindrical base plates 2.16 by .36 meters (weighing 5} tons) for supporting the cylindrical flanged shoe. 0.612 meter in diameter bolted to the standard. An 800-tou hydraulic jack is placed in the hollow space below the shoe, for raising and supporting the standard (see p. 821). Steel strips or wedges ate inserted between the up- lter rim of the base plate and the flange of the shoe, to keep the standard at the proper height. inder is of wrought iron 95 millimeters thick and the piston is 430 millimeters in diameter. 816 UNIVERSAL EXPOSITION OF 1889 AT PARIS. (339) Erection of the first, story . — By the end of June, 1887, the foundations were completed and the erection of the ironwork began. The lower parts of the columns were erected by braced shears 22 me- ters high, in the form of the letter A. They were made of timber and provided with a pulley at the top, over which a chain passed to a winch on the ground (Fig. 234). CIVIL ENGINEERING, ETC. 817 The sections of the standards, in the form of caissons 0.80 meter square, weighing from 2,500 to 3,000 kilograms each, were success- fully placed on each other and joined, first by pins, then by bolts. After the sections came the latticework and braces uniting the por- tions of the standards already erected, fixing them in their relative positions and consolidating the whole structure. Behind the gangs of adjusters came the riveters, who removed the bolts and replaced them by rivets driven hot, forming the per- manent junction between the pieces. When the structure had reached the height of 15 meters, the shears were replaced by special cranes. The inclination of the standards naturally tended to over- set them, but this tendency would not be effective until a height computed to be 30 meters was reached; so that up to this height the standards could be erected, so far as their stability was concerned, just as if they were vertical. Besides the calculated theoretical security, there was that resulting from the anchorage, which was more than sufficient in this case to prevent any movement. The erection proceeded steadily until the height of 30 meters was reached. The weight of the pieces already placed in position ex- ceeded 1,450 tons. (340) Erecting scaffoldings . — To continue the erection, wooden scaffoldings 30 meters high were built on piles, and planted so as to sustain at their tops the three interior standards of each pier. At the top of each scaffolding was a strong platform on which were placed sand boxes such as are used on the centering of arched bridges. Accessory brackets, which were afterwards removed, were at- tached to the standards, their horizontal faces resting on the sand boxes, thus forming the support of the iron pier on the wooden scaffolding. This support once obtained, the work of erection went on up to the level of the first story of the tower. The sand boxes afforded a means of rectification in case of any deviation of the structure from its true position. If the column re- quired to be lowered a little, some of the sand could be run out, and the iron work then sank to the desired position. If, on the contrary, the column had to be raised, it was easily done by hydraulic jacks placed on the platform beside the sand boxes, and acting against the temporary bracket. In this way the work was under perfect con- trol. In the construction of the twelve scaffoldings just described, 600 cubic meters of wood were used, and the erection was continued to a height of 50 meters. At this level the horizontal girders were laid, uniting the four piers and forming the first story. The special cranes which were used had a range of 12 meters: this was sufficient to be within reach of the four standards. The cranes had a power of 4 tons each, and were worked upon the inclined girders forming the guides for the elevators. H. Ex. 410 — vol iii 52 818 UNIVERSAL EXPOSITION OF 1889 AT PARIS. When the piers had attained a height of 55 meters the first great belt of horizontal girders was put in, running from pier to pier. These girders, 7.50 meters high and weighing 70 tons each, were so constructed as to adapt them to the inclined faces of the converging columns. These conditions, in addition to the great height at which they were to be placed, rendered it necessary to erect for this purpose a new scaffolding 45 meters high, with a platform 25 meters long. Four such scaffoldings were erected, one for each face of the tower. The central parts of each of the horizontal girders were hoisted and riveted on these scaffoldings; the adjacent portions were then added to the right and left so as to unite the four' piers, the opera- tion being carried on simultaneously for all four faces. Plate XIV is a near view of this scaffolding and its superimposed girder. When these girders were joined together they formed a strong horizontal frame which took the thrusts due to the obliquity of the four piers. (341) 77/e erecting cranes . — We shall now describe the construction of the erecting crane above alluded to. Up to a distance of 15 meters the pieces were raised by shears and winches, but when that height had been reached the following special crane was devised by MM. Guyenet and Eiffel, which is thus described by M. Nansouty: It consists (Fig. 235) of a long jib, turning on a pivot mounted on a frame having the form of a triangular pyramid upside down. The pivot is placed in the axis of the pyramid, with the pivot step at the apex. The base of the pyramid is the operating platform, and one of the sides of this base is connected to a frame formed of two lon- gitudinal and two transverse beams. This last frame supports the whole weight, and transmits it to the inclined elevator guides which wei’e erected with the piers. The flanges of these guides are pierced with holes at equal distances. Similar holes are bored in the longi- tudinal beams of the frame carrying the crane; by means of these holes the two are bolted together. (342) Method of raising the crane. — When all the pieces within the range of the crane had been raised and riveted together, it was necessary to raise the crane in its turn; this was accomplished thus': A strong iron beam, through the center of which passed a large screw, is bolted horizontally upon the guides at about 2.50 meters above the crane frame. The screw passes through the frame, and is secured by a nut. Now if the bolts are withdrawn from the frame and the guides, the crane will hang from the iron beam suspended by the screw. By turning the nut, the frame slowly ascends to its new position, the bolts are replaced, and the work goes on. When the crane is again to be raised (supposing the nut to be near the end of its course) the crossbar is detached, carried up, again bolted to the guides, the screw put in, and the process is repeated. Two jacks were placed under the frame in case of the rupture of the principal screw. Paris Exposition of 1889— Vol. 3. Civil Engineering, etc. — PLATE XIV. JF NjgQ ■ ' W THE EIFFEL TOWER. NEW SCAFFOLDING, 45 METERS HIGH, USED IN JOINING THE ISOLATED PIERS. CIVII. ENGINEERING, ETC 819 Fig. 335.— The erecting cranes especially devised by MM. Guyeuet and Eiffel, used iu the erection of the first and second stories . 820 UNIVERSAL EXPOSITION OE 18S9 AT PARIS, Fig. 230. — View of the fir>t story, showing one of the four piers of the tower and the shelter for the portable hoisting eugine, the circular railroad, etc. Paris Exposition of 1889— Vol. 3. Civil Engineering, etc.— PLATE XV. THE EIFFEL TOWER. DETAILS OF THE IRONWORK OF THE STRUCTURE CIVIL ENGINEERING, ETC. 821 Another peculiarity of this crane is the mechanism by which the range is changed. This is effected as follows The ties of the jib are attached to an axle mounted on rollers and moving vertically on the crane post by means of a screw and nut. This simple device allows the range of the loaded jib to vary from 3 to 12 meters. It is susceptible of yet another movement about a horizontal axis by which its verticality is assured whatever be the inclination of the guides upon which the frame moves. This is accomplished by a screw fixed to the frame, which drives a nut placed in the pivot step. Again, the suspending hook is furnished with a hand screw. The pieces to be riveted may, so to speak, be mathematically adjusted. Four of these cranes were used upon the four piers up to the height of 150 meters. Each one weighed 12 tons and could lift 4 tons. (343) Erection of the first and second stories . — The piers between the first and second stories were rapidly erected by the same method as that employed below, i. e., by means of four cranes working on Fig. 237. — One of the 800-ton hydraulic jacks. the elevator guides. But a new arrangement was made, after the completion first story, for lifting the material, the distance to the ground being too great for one set of cranes to lift it to its position. On the first story a circular railroad was laid down, and a crane set up driven by a portable engine of 10-liorse power, which lifted the materials from the ground and deposited them on cars, by which they were carried to one of the four cranes which raised them to their final position. (Fig. 236 and PI. XV). The work advanced with such rapidity that on the 14th of July, 1888. the fireworks, celebrating the national fete, were discharged from the second platform, 115 meters above the ground. (344) Use of the 800 -ton jack . — “When preparations were made to join the four pillars, in pairs, by horizontal beams, above the second story, it was found, as had been the case on the first story, that there was a slight difference between the piers. The difference arose from UNIVERSAL EXPOSITION OF 1889 AT PARIS, 822 the fact that the piers 2 and 3 were a little higher than the others, the difference being between 5 and 6 millimeters. As no alteration of the parts could be made on the spot, the discrepancy was corrected by lowering these two piers and slightly widening the distance be- tween them. This operation was affected by means of the hydraulic jacks above described.”* (Figs. 237 and 238.) * Tessandier. Fig. 938. — Operation of lifting one standard of the tower by an hydraulic jack, for the purpose of driving in the wedges. CIVIL ENGINEERING, ETC 823 (345) The erecting cranes above the second story. — Above the sec- ond story, i. e., above 115 meters, considerable modification had to be made in the system of erection. (Fig. 239 and PI. XVI). Fio. *239.— Arrangement of the crane for constructing: the tower above the second story. Height 215 meters. December. 1S88. 824 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The oblique elevator guides no longer exist, but are replaced by vertical ones belonging to another system (Edoux). This system was introduced because the curved form of the tower, by bringing the columns together, had considerably reduced the horizontal section. Instead of four cranes, two were sufficient. To support these two cranes and provide a substitute for the elevator guide ways, M. Eif- fel made use of the vertical guide pillars introduced between the second story and the top of the tower. The cranes were like those already used, but so modified as to adapt them to be hoisted against a vertical guide instead of resting on the inclined ones. To balance them they were fixed back to back on the central elevator guide pillar. To increase the surface of support three iron frames were also bolted to the pillar. These frames were 3 meters high, and wide enough to allow the crane frame to be bolted to their vertical sides. Safety appliances were used as before, and, in addition, the cranes and auxiliary frames were firmly united together by a system of temporary beams, so as to form one solid structure. A whole panel of the tower, 10 meters in height, could be erected without shifting the cranes. The three squares thus placed one above another formed a vertical road of 9 meters, upon which the cranes could move by the lifting screws. (346) Method of shifting the cranes . — When a crane had traveled up the three sets of squares and had to go higher, another set of three squares was placed in position, the crane was then moved up. and the first three squares were free to be used subsequently. Jacks were placed under the squares as well as under the cranes, so that in case of the failure of the bolts the cranes would remain in position (PI. XVI). The time required to make the shift from one panel to another was about 48 hours, a short time when it is considered that the total weight to be moved amounted to 45 tons. The erection above the second story may be thus summed up : A steam winch on the first story raised the material from the ground, a second winch of the same kind on the second story raised it to this level, i. e. 1 15 meters. A third steam winch, set up on an interme- diate flooring of the Edoux elevator, 197 meters high, brought the pieces to the cranes, which put them in position. (347) Protection of the workmen . — The workmen were provided with movable platforms furnished with a hand rail and screen. These were first placed in position by carpenters, and occupied succes- sively by the adjusters and riveters. Only one accident happened by falling and that was at the beginning of the work. (348) Top of the tower . — The upper portion of the tower termi- nates in a cornice, supporting the campanile and the light-house. The lower part of the campanile consists of a covered gallery, 16 me- Paris Exposition of 1889— Vol. 3. Civil Enoineering etc. — PLATE XVI. THE EIFFEL TOWER. THE ERECTING CRANE USED ABOVE THE SECOND STORY. CIVIL ENGINEERING, ETC. 825 ters on each side, and will accommodate 800 persons. It is fitted all around with glazed sashes, which can be opened or closed at will, the closing of the windows being necessary in strong winds. (Fig. 240). Fir,. 240.— Campanile of the tower. The summit of the tower, formed of four lattice arches placed diagonally to the square section, supports the light-house. Above the cupola is a small terrace 1.40 meters in diameter, to which access is obtained by a ladder in the lantern. This terrace, 820 UNIVERSAL EXPOSITION OF 1889 AT PARIS. which is 300 meters above the ground, is specially designed for the anemometers and other meteorological instruments. (349) Staircases. — In the east and west piers there are straight staircases 1 meter wide, with numerous landings, giving easy access to the first floor and consisting of three hundred and eighteen solid oak steps. The former is used for descending and the latter for ascending, and it is estimated that a file of 2,000 persons per hour could be accommodated by them. From the first to the second story a spiral staircase, 0.60 meter wide, is arranged in each of the piers ; two of these staircases are for the ascending and two for the descending visitors. They also will accommodate 2,000 persons per hour. From the second story to the top there is a spiral staircase 160 meters high, which is simply a service staircase and not open to the public. (350) Arrangement of the first story. — Upon the first story, which covers an area of 4,200 meters, an arcaded open gallery is arranged for visitors who wish to enjoy the view of Paris, its environs, and the exhibition. This promenade is 283 meters long and 2.60 meters wide. There are also four large restaurants, capable of containing from 500 to 600 persons each. They are built in different styles of architecture and are called the Russian, the Anglo-American, the Alsace-Lorraine, and the French restaurants. A general view of the lower part of the tower and the first story is given Plate XVII. (351) 7 he second story has a surface of 1,400 square meters. It' has a covered gallery forming a second promenade 150 meters long and 2.60 meters wide. The central part contains the stations for the elevator, and at one end is the office of the newspaper printed, stereo- typed. and published here, called the “Figaro de la Tour Eiffel,” the rotary printing press being worked by a gas motor. (352) The third story is octagonal in shape, consisting of four sides 12 meters in length and four small ones of 2 meters. An iron staircase of ten steps leads up to the private rooms of M. Eiffel, and to those devoted to scientific observations. From these a straight staircase of thirty steps leads up to the springing lines of the iron lattice arches supporting the campanile; thence a spiral staircase leads, at the top of these arches, to an iron cylinder contain- ing a ladder of twenty steps leading to an octagonal lodge with a balcony. Through an iron trapdoor at the top of ten steps more we come into the lantern itself. Passing through this, up one more ladder, we come out upon a small balcony containing the flagstaff, and at a height of 300 meters above the ground. (353) The elevators. — Independently of the staircases, the ascent is facilitated by a certain number of elevators of different systems, viz: (1) The Roux-Combaluzier and Lepape system; (2) the Otis; (3) the Edoux. Paris Exposition of 1889— Vol. 3. Civil Engineering, etc.— PLATE XVII. THE EIFFEL TOWER. THE FIRST STORY. CIVIL ENGINEERING, ETC. 827 From the ground to the first story there are four elevators, two on Roux-Combaluzier and Lepape system, and two on the Otis system. From the first to the second stories the ascent is effected by the two Otis elevators, which, run continuously from the ground to the second story. Finally, from the second story to the third, the Edoux system is used. Its starting point is from a platform erected halfway between the second and third stories. It is worked by water power with a vertical piston having a cage on the top. This cage affords the means of transit to the third story, a distance of 80 meters above the inter- mediate platform. It is attached by chains to a second cage forming a counterpoise. This cage brings the passengers from the second story, 80 meters below, up to the intermediate platform. In this way the passengers, by changing from one cage to the other at the intermediate platform, make the ascent of 1G0 meters from the sec- ond to the third story. (354) Time of ascent . — The Roux-Combaluzier and Lepape system takes 100 passengers, who are landed at the first story within the minute, at a speed of 1 meter per second. The Otis elevator cage holds 50 passengers, but has an ascensional velocity of 2 meters per second. The Edoux elevator cage accommodates 63 persons, the ascensional velocity is 0.90 meter per second, and the time is 1| minutes for each course and 1 minute for changing cages, i. e., 4 minutes for the as- cent from the second to the third platform. All the elevators are furnished with safety apparatus. They are operated by hydraulic power, the water furnishing this power being raised by steam pumps of 300 horse power. The elevators can take up to the first and second stories 2,350 persons per hour, and 750 persons up to the third, the complete as- cent occupying 7 minutes. By means of the staircases and elevators combined the tower can be visited by 5,000 persons per hour. The mechanical features of these elevators are described in the report on class 52. (355) Verification of the verticality of the tower . — This was ac- complished when the tower had attained a height of 220 meters by MM. Thuasne and Seilhac. This verification consisted in observing whether the median lines on each face of the tower were situated in the principal planes of the tower. By a median line of a surface is meant a line situated in a vertical plane and passing through the center of gravity of that surface. A principal plane is a vertical plane passing through the lines A A (Figs. 241, 242). For this pur- pose points a, h, c, d, e,f, and the intersection of the diagonals of the lattice situated upon the median lines of the four faces were selected. The median lines being thus traced on the tower, the operation consisted in observing, with a theodolite placed in the plane A A 828 UNIVERSAL EXPOSITION OF 1889 AT PARIS, and properly adjusted, whether the points a, b, c, cl, e, f coincided with the vertical wire of the telescope when rotated in a vertical plane. Verification of the vertically of the tower. if -o Fig, 242.— Plan. CIVIL ENGINEERING, ETC. 829 These observations were made upon each of the four planes (4-1), (1-2). (2-3), (3-4) at points situated upon the lines A A, A A at dis- tances from the axis of the tower varying from 100 to 300 meters. One of these stations of observation was upon the Jena bridge about 250 meters from the axis of the tower. The vertical wire of the telescope was found to coincide absolutely with all the points a, b, c, d, e, and the crossings of the diagonals; hence all these points were in the principal plane. Similar observa- tions made at three other stations showed the tower to be abso- lutely vertical. (35G) Uses of the tower. — M. Eiffel thus described the uses of the tower in an address to the members of the “ Socidtd centrale du Tra- vail Professionnel The construction of the tower will enable us to observe, with new effects of light a prospect of incomparable beauty, before which no one can fail to be deeply im pressed with the grandeur of nature, and the power of man. But besides its soul inspiring prospects, the tower will have varied applications for our national defense as well as in the domain of science. (357) Strategical operations. — “ In case of war or siege it would be possible to watch the movements of an enemy within a radius of 70 kilometers, and to look far beyond the heights on which our new fortifications are built. If we had possessed the tower during the siege of Paris, in 1870, with its brilliant electric lights, who knows whether the issues of that contest would not have been entirely changed? The tower would have provided the means of easy and constant communication between Paris and the provinces with the aid of optical telegraphy, the processes of which have attained such remarkable perfection”. (Nansoutv.) It is situated at such a distance from the defensive forts as to be out of the reach of the batteries of the enemy. (358) Meteorological observations. — It will be, moreover, a wonderful meteorologi- cal observatory in which may be studied the direction and force of the atmospheric currents, the electrical state and chemical composition of the atmosphere, its hy- grometry, etc. (359) Astronomical observations. — As regards astronomical observations, the purity of the air at such a height, the absence of the mists which often cover the lower horizons in Paris, will allow many physical and astronomical observations to be made which would be often impossible in our region. (360) Scientific experiments maybe made, including the study of the fall of bodies in the air, the resistance of the air according to speed, certain laws of elasticity, the study of the compression of gas and vapors by an immense mercurial manometer having a pressure of 400 atmospheres ; anew realization on a large scale of Foucauld pendulum, showing the rotation of the earth, the deviation toward the east of fall- ing bodies, etc. It will be an observatory and a laboratory such as has never before been placed at the disposal of savants, who from the beginning have encouraged the undertaking with their warmest sympathies. My wish has been to erect a triumphal arch for the glory of science and the honor of French industry, as striking as those reared to military conquerors by former generations ; and to express in a most emphatic manner that the monument I raise is placed under the invocation of science, I have inscribed in golden letters under the great frieze of the first story and in the place of honor the names of the great savants who have honored France for the last century. 830 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Between the brackets is a frieze on which are inscribed in golden letters, perfectly legible from below, the names of the men who have honored French science. On the Paris side : Petiet, Daguerre, Wurtz, Perdonnet, Delambre, Malers, Breguet, Polonceau, Dumas, Clapeyron, Borda, Founder, Bichat, Sauvage, Pelouse, Carnot, and Lamd. Trocadero side : Seguin, Lalande, Tresca, Poncelet, Bresse, La- grange, Belanger, Cuvier, Laplace, Dulong, Chasles, Lavoisier, Ampere, Chevreuil, Flacliat, Xavier, Legendre, Chaptal. Crenelle side; Jamin, Gay-Lussac, Fizeau, Schneider, Le Clnite- lier, Bertliier, Barruel, de Dion, Gouin, Jousselin, Broca, Becquerel, Coriolis, Cail. Triger, Giffard, Perrier, and Sturm. Towards the Ecole Militaire : Cauchy, Legrand, Regnault, Fres- nel. Prony, Vicat, Ebelmen, Coulomb, Poinsot. Foucault, Delaunay, Morin, Hauy, Combes, Thenard, Arago, Poisson and Monge. Plate XVIII gives a general view of the complete structure. (301) Statistics . — The weight of the iron contained in the tower is about 7,300 tons. The weight of the rivets is 450 tons and their total number 2,500,000. Of this quantity 800,000 were hand driven on the tower for uniting the parts already prepared. The number of metallic pieces is 12,000, which, on account of their varying form and position in space, required special drawings. Forty draftsmen and computers worked steadily for two years to complete the plans, specifications and computations. It took ten draftsmen from 8 o’clock in the morning to 10 o’clock at night for one month to prepare the drawings for one panel, i. e. 10 meters of the tower. The drawings were made with great pre- cision up to the ten-thousandth of a meter. The plans of the tower comprised 500 drawings and 2,500 working drawings for the whole 27 panels. Each piece of which the tower was built was designed, shaped, and bored at the works at Levallois- Perret and was found to fit exactly into its place when it reached the Champ de Mars. From 150 to 200 men were employed, at the rate of 0.80 to 1 franc per hour. (362) Color . — The tower is painted a chocolate color, which is de- scribed as a reddish bronze, from the foot to the first story; from the first to the second story the same tint, but lighter; from the second story to the top it becomes lighter and lighter until the cupula is almost yellow. (363) Cost . — Francs. Foundations, masonry, pedestal . 900,000 Erection, metal, city duties on the iron 3,800,000 Painting, four coats 200,000 Elevators and machines 1, 200, 000 Restaurants, decorations, different buildings 400. 000 Total 6,500.000 Paris Exposition of 1889— Vol. 3. Civil Engineering, etc.— PLATE XVIII. COMPLETE VIEW OF THE EIFFEL TOWER. CIVIL ENGINEERING, ETC. 831 (3G4) The Mont-yon prize in mechanics . — The F reach Academy of Sciences has just awarded the Montyon prize of mechanics to M. G. Eiffel as a mark of their appreciation of his skill in the erection of iron structures. (365) Acknowledgment . — I wish here to express my obligations to MM. Eiffel, Salles, and Nouguier for numerous courtesies received, as well as for information, printed descriptions, and heliographs, of which liberal use has been made in this report. Figures 231, 235 to 239, inclusive, are from copies of La Nature, and Figs. 233, 234, 240 to 242, inclusive, are from Xansouty's book on the Eiffel tower. Supplementary note . — In order to show some of the opposition to M. Eiffel's scheme for a tower 300 meters high the following extract from Engineering is appended : On the 5th of November, 1886, the finance committee of the Paris Exhibition voted a credit of 1,500,000 francs as a subsidy for the unique and monumental work M. Gustave Eiffel had undertaken to construct, and which was to be one of the great original features of the exhibition. The idea of erecting a tower 1.000 feet in height was received with a very general feeling of distrust and even of dismay ; not that anyone doubted the capability of the bold and successful engineer to com- plete the work to which he had pledged himself, but the misgivings were very general as to the effect that such a novel construction would have upon the archi- tectural features of the Exhibition, and a widespread cry of influential voices went up from Paris as a protest against the engineering outrage that was to be inflicted upon the Frencii metropolis. It is rather curious, now that the tower is completed and the great consensus of public opinion is loud in its approval, to recall the re- monstrances addressed to M. Alphand, the Director-General of Works, against the proposed column. “ We wish — authors, painters, sculptors, architects, enthusiastic lovers of beauty — which has hitherto been respected in Paris — to protest with all our energy, and with all the indignation of which we are capable, in the name of art and of French history now menaced, against the erection in the heart of our cap- ital of the useless and monstrous Eiffel tower, which public satire, often full of good sense and a spirit of justice, has already christened the Tower of Babel. With- out falling into extravagance we claim the right to assert that Paris stands without a rival in the world. Above its streets and boulevards, along its quays, amidst its magnificent promenades, abound the most noble monuments which human genius has ever put into execution. The soul of France, creator of chefs-d’oeuvre, shines forth from this wealth of stone. Italy, Germany, Flanders, so justly proud of their artistic heritage, possess nothing comparable, and from all corners of t lie uni- verse Paris commands admiration. Are we. then, going to allow this to be pro- faned ? Is the city of Paris to permit itself to lx* deformed by monstrosities, by the mercantile dreams of a maker of machinery; to be disfigured for ever and to be dishonored? For the Eiffel tower, which even the United States would not coun- tenance, is surely going to dishonor Paris. Everyone feels it. everyone says so, everyone is plunged into the deepest grief about it. and our voice is only a feeble echo of universal opinion properly alarmed. li When foreigners will come to visit our exhibition they will cry in astonishment: ‘ Is this horror that Frenchmen have invented' intended to give us an idea of the taste of which they are so proud? And they will be right to mock us, because the Paris of the sublime architects, the Paris of Jean Goujon, of Germain Pilon, of Puget, of Rude, of Barye, will have become the Paris of M. Eiffel. Nothing further 832 UNIVERSAL EXPOSITION OF 1889 AT PARIS. is wanting to prove the justice of what we say than to realize for an instant this tower dominating Paris, like a gigantic and black factory chimney, crushing, with its barbarous mass, Notre Dame, the Sainte Chapelle, the Tour St. Jacques, the Louvre, the dome of the Invalides, the Arc de Triomphe ; all our monuments hu- miliated, all our architecture shrunken, and disappearing affrighted in this bewild- ering dream. And during twenty years we shall see, stretching over the entire city, still thrilling with the genius of so many centuries, we shall see stretching out like a black blot the odious shadow of the odious column built up of riveted iron plates.” And so forth, and so forth. To this vehement protest were attached the names of many of the best-known men of France — Meissonier, Gounod, Gamier, Sardou, Gerome, Bonnat, Bouguereau, Dumas, Copp6e, etc. But these well-meant ill-judged remonstrances were not heard, and to-day the Eiffel tower stands com- pleted. the marvel of the exhibition and the glory of the constructor. The noble monuments of Paris apparently thrill as much as the} - did before with the genius of the centuries, and the grand proportions of the Arc de l'Etoile do not seem to have suffered because a great French engineer has achieved a triumph of construction. If foieign criticism was not set forth in such brave words as those we have quoted above, it was none the less hostile ; but foreign criticism is generally more or less colored by jealousy, and is therefore not of much account. Chapter XLYI. — The Machinery Hall. (36G) The enormous machinery hall is justly considered the bold- est work of the exhibition; it illustrates the extraordinary progress of engineering, and its new lessons in the art of construction are already beginning to be applied. (3G7) The Osiris prize . — A committee of French journalists to whom was assigned the task of awarding the Osiris prize of 100,000 francs to the most important work of the exhibition, after having paid a just tribute to the palaces of the fine and of the liberal arts, constructed by M. Formigfi, and to the central dome by M. Bouvard, decided to give it to the constructors of the machinery hall. M. Dutert, the architect who conceived the idea, prepared the plans, and superintended the erection, received 20,000 francs; M. Contamin, who prescribed the dimensions and calculated the strength of all the ironwork, 15,000 francs ; to the five assistant architects and engi- neers, 3,000 francs each; the other 50,000 francs were distributed among the workmen. (3GS) History . — In 1878 M. de Dion made a bold beginning by con- structing the gallery of machines with a single iron arch without a tie-rod, the trusses forming one solid piece with the piers, and built into the masonry; but these trusses were of only 30 meters span, and the height did not exceed 25 meters. In the railroad station at St. Pancreas, in London, the trusses have in appearance no intermediate point of support; in reality the ends are united by tie-rods concealed beneath the flooring; the span is only 73 meters. In 1889 the system adopted had already been employed by Oudry in the construction of the swinging bridge at Brest, for a few iron CIVIL ENGINEERING, ETC. 833 viaducts, and in some railroad stations in Germany, but it had never before been applied on so gigantic a scale. Before entering upon a detailed description of the construction and erection of this remarkable building it may not be out of place to show by the following extract from one of the Paris journals,* what impression the sight of this vast edifice produced upon the- enlightened public. If the Eiffel tower was an unexpected surprise, a triumph of originality and of daring skill, the machinery hall was found lo be only one degree less marvelous; and this because the progress of modern architecture and of the science of engineer- ing had. from one decade to another, led us up to this superb realization of the un- explored possibilities of both. Never before, in the opinion of engineers of all countries who have visited it, has a building, proportionately to its vast dimensions, been constructed with such a wondrous combination of solidity, lightness, amt grace, the general effect being enhanced by the flood of light freely admitted to all parts of the palace. The Government is therefore to be most heartily' con- gratulated, on national and artistic grounds alike, upon the initiative which it has taken to permanently preserve this magnificent building, together with those set apart to the fine and liberal arts, in addition to the grand central dome. The machinery hall is, indeed, the most prodigious outgrowth of the joint ingenuity and skill of architect and engineer. To bring under one roof all the machinery that was to be exhibited was a problem which almost defied solution. The task, however, was happily surmounted by the cooperation of M. Dutert, the eminent architect, and MM. Contamir, Charton, and Pierron, engineers. M. Dutert. who conceived the entire plan of the work, tracing it out even to its minutest features, superintended tne decorative details. Taking up this vast conception of an artist, M. Contamin stamped upon it the hall-mark of science by calculating the efforts of the materials, estimating their resistance, and insuring the due solidity' and equi- librium of the whole structure. He it was who superintended the operation of fitting together the ribs and girders and general framework resting upon the solid squares of masonry constituting the foundations. The palace is 420 meters in length, and 115 in width, covering a superficial area of 48,335 square meters, or about 114 English acres. f It is estimated, indeed, that should the building be ulti- mately converted into a military riding school, it will afford ample space for exercis- ing 1 ,200 horses at a time. Some further idea of its commanding proportions may be conveyed by the statement that the Vendome column, with its well-known statue of Napoleon I, might easily be erected within the four walls, as it would leave 7 meters to spare between the head of the figure and the apex of the arched roof ; that the span of the girders supporting this roof, which is 48 meters in height, would shelter the Arc de Triomphe; and that the nave of the Palais de l’lndustrie is only half the length and half the width of that of the Palais des Machines. There is sufficient “free play” at the top of the arching girders to allow of the slight displacement that takes place under the action of heat and cold. The only points of support are, in fact, at the base of the girders and where these latter meet each other in the center of the roof: but these chief ribs, be it noted, are connected by longitudinal girders, the whole framework being otherwise strengthened, on each side of the building, on the most approved principles. The method which was fol- lowed enabled the constructors to carry out their plans with the minimum of mate- rials commensurate with necessary strength and artistic effect: and the entire cost of the palace (7,514,095 francs, of which 5.398,307 francs was for ironwork alone) *Galignani's Messenger, July, 1889. t The nave alone, not including the lateral galleries. H. Ex. 410— VOL III 53 834 UNIVERSAL EXPOSITION OF 1889 AT PARIS. was correspondingly lessened. Over the summit of the roof is a narrow gallery for workmen. Each of the arched girders running up the sides of the building consists of two ribs, an inner and outer one, solidly bound together, above and below, crosswise, one regular square alternating with an elongated one, the only real point of sup- port being, as we have said, in the masonry at the base, inasmuch as the girders meet each other lightly, with a sort of elastic touch at the apex above. The total weight of material over the grand nave is only 7,400 tons, a little more than the mass of iron used in the construction of the Eiffel tower. On either side of the ma- chinery hall is a gallery 15 meters in width, to which access is obtained by broad staircases, as also by lifts. One point deserving special mention is that the contract for the building was divided between two firms. One-half of the palace, that on the Avenue de Labourdonnais side, was constructed by the Compagnie Fives-Lille, and the other half, stretching to the Avenue de Suffren, by the Societe Cail. The former company put its girders into position in heavy sections, some of these weigh- ing 48 tons apiece, whilst those of the other contractors were set up in fragments of 3 tons. Had steel been used, the framework would have been much lighter than it is, but the idea of resorting to it was abandoned on the two-fold ground of expense and the necessity of hastening the execution of the work. Those who believed that iron was ill adapted to the requirements of art as applied to industry have been agreeably surprised by the happy results achieved by M. Dutert and the engineers who so ably cooperated with him in this veritable palace of wonders. The internal decorations, under the glass roof arching downwards toward the sides, are most effective, the chief tone being of a rosy yellow giving rise to some curious effects of the sun's rays. Thus, toward evening, all the panes over the right side of the nave assume a rosy tint, whilst those opposite are of a light-green hue, the contrast suggesting that between rubies and emeralds. Ten large panels and one hundred and twenty-four smaller ones have been painted by MM. Alfred Rube, Philippe Chaperon, and Marcel Jambon ; the former represehting the arms and commercial or other attributes of the leading capitals of the world (Berlin, of course, excepted), and the latter the escutcheons, etc., of the minor cities and towns, including all the chefs-lieux of French departments. Over the chief en- trance in the Avenue de La Bourdonnais, is a large rose window in different colors. The ornamentations on the outside are exceedingly striking. The vast arch over the porch is decorated with a foliated design showing between the leaves various implements of labor. On the lintel is the inscription “Palais des Machines,” in decorative faience, the groundwork being an olive branch. This is supported by two groups 10 meters in height.* The first, by M. Barrias. represents electricity, and is composed of two female figures. One of these, bv a finger touch, sends an electric flash through the globe, whilst the other, resting in a recumbent position on a cloud, stretches forth her band to her companion: they symbolize the two opposite currents. The second group, by M. Chapu, shows a female figure personi- fying steam, and a workman clasping her in his arms. A colored window above sets forth the arms of the various powers taking part in the exhibition. In the center of the gable at the opposite end are some colored panes depicting the battle of Bou- vines.f and facing the Ecole Militaire is a window dedicated to the “Chariot of the Sun.” Those who enter the machinery hall from the general industries gallery pass through a central vestibule which from its rich decoration, may be regarded as a sort of salon d'honneur. Here is a handsome cupola covered with colored panes and mosaics, the former showing the leading agricultural products of the country, such as flax, hemp, wheat, and maize. The painted pendentives represent the arts, See Plates XXI and XXII. f Plate XX. CIVIL ENGINEERING, ETC. 835 sciences, letters, and commerce. The numerous other allegorical subjects ornament- ing the vestibule have been greatly admired. At the foot of the handsome stair- case leading to the gallery are two splendid bronze figures, each bearing a cluster of twenty incandescent lamps. Such, in brief, is the general outline of the building itself. It may be urged that the Palais des Machines affords evidence that a fresh era in architecture has been inaugurated, that ceci tuera cela, and that the age of stone is to be succeeded by the age of iron. We do not think so. It is true that the engineers are just now triumphant in many directions. The chief of the state is an engineer; an engineer, M. (le Freycinet, is minister of war; M. Alphand, another engineer, was one of the organizing directors of the Universal Exhibition; and the name of the engineer, Eiffel, has become something more than a household word. With respect to the architectural question, however, it is evident that engineers can dictate to archi- tects only in the case of immense buildings whose distinctive characters is, after all, that of use rather than ornament. Those, however, who look at the interior of this machinery hall for the first time can not form an estimate of its imposing dimensions; its architectural lines do not draw the attention upwards, and so its roof appears lower than that of the smallest Gothic cathedral. Nobody, at a glance, would imagine that he stood in the highest covered building in the world. The motive power is distributed by means of four shafts extending from one end of the building to the other, the total force actually at work being equal to 2,600 horse power, although 5,640 horse power may be developed if necessary. This is more than double the power placed at the disposal of exhibitors in 1878. In 1855 the figure stood at 350 and in 1867 at 638. There has, therefore, been a remarkable progression. Visitors may watch the machinery in movement from two traveling cranes, or pouts roulants, as they are more correctly described in French, which move to and fro on rails at some height above the shafts. The bird's-eye view thus obtained proved so startling to an Annamite the other day that he turned suddenly pale, or pale yellow, on glancing down at the iron monsters which to his untutored and superstitious gaze seemed to be harboring destructive designs upon the passing crowds, and he looked as though he were ready at a moment’s notice to prostrate himself at the feet of some modern Moloch! The steam boilers occupy a place in a covered court facing the Avenue de Lamotte-Piquet, and it should here be stated that the machinery on the Quai d’Orsay is set in motion by the engines in the ma- chinery hall, a motor turning a dynamo for the transmission of electricity to the agricultural hall. Most of the engines exhibited in the Palais des Machines belong to the Corliss. Sulzer. and Wheelock systems, and are generally of the compound type, but others will also be studied with interest by technical judges. The general arrangement of the exhibits may lx* described in a few words. As the visitor passes through the palace from the Avenue de Suffren to the Avenue de Labourdonnais, he finds that the first half on his right is devoted to those relating to civil engineering, the ceramic arts, cabinet-making, mechanism of various kinds, electricity, agriculture, mining, and metallurgy, printing, and paper-making; and the other half, on the left, to railway material, and spinning, weaving, and iron working machinery, etc., and the special places set apart to Switzerland, Belgium, the United States, and England. Between the machinery ball and the general in- dustries gallery is a court in which electrical apparatus of all kinds may be seen in full working order at night. It constitutes one of the most novel and attractive features of the exhibition. The focus of one great lamp consists of a cluster of 15,000 small incandescent lights. (3G9) Extract f rom the official specifications. — The following ex- tract from the official specifications will give an idea of the great pressures which the foundations were required to sustain. 836 UNIVERSAL EXPOSITION OE 1889 AT PARIS. The great nave consists of nineteen bays, varying in length as follows: Two at the end. of 25.295 meters each; sixteen intermediate, of 21.50 meters, and one in the middle, of 26.40 meters. There are twenty principal girders (Fig. 247), the two end ones being heavier than the others. These principal girders are connected at the top by two ridge purlins, with a walk and parapet above them, and on the sides by eight lattice purlins, and two plate purlins at the right of the main gutters. Between the principal girders each bay is divided into four parts by three girders at right angles to the purlins, to which they are attached. These latter hold the minor purlins and sash bars, with the iron framing for the roof covering. Later- ally, the principal girders are connected by lattice girders at the first floor level of the side galleries, and under the gutter by lattice arches and open iron work. The weight of the nave was estimated at 7,709,100 kilograms, and the thrust of each principal girder amounted to 1 15,000 kilograms, including a weight of snow and the effect of a strong wind blowing at the rate of 40 meters per second. (370) Foundations . — The foundations for the Machinery Hall were begun on the 5th of July, 1887, and were finished on the 21st of December. The structure, according to the specifications just given, consists of an immense nave 110 meters wide and 420 long, with two side galleries 15 meters wide, containing a single story 8 meters above the ground, with grand stands at each end, supported on iron pillars. Access to this story is obtained by four great staircases. The twenty great curved girders of 110 meters span form the framework of the building; they are jointed at the top and at the springing lines. The axles on which they rest are on a level with the ground. The bed plates or cast-iron bearings, which take up the thrust of the arch and transmit it to the masonry, had to be made strong enough to support a vertical load of 412 tons, and a horizontal thrust of 1 15 tons. As provision had to be made for a system of underground pipes for water, steam, drainage, etc., it was impossible to use under- ground tie-rods ; it was, therefore, absolutely necessary to make the foundations of the piers or abutments of the great girders strong and deep enough to assure the perfect security of the edifice. The twenty great girders rest on forty masonry piers entirely hidden in the ground ; they are designated by the letters A, B, C, etc. (Fig. 243). (371) The nature of the soil is suitable for foundations, where it has not been previously disturbed, but unfortunately for the present occasion, the Champ de Mars has, during the last century, been the site of exhibitions beginning with that of 1780 and ending with the recent one of 1878, when a deep deposit of sand was removed and replaced with rubbish. On this old gravel pit a portion of the foundation had to be made (this portion is shaded in the figure). Numerous borings had shown the strata (Fig. 244) to be as follows: made ground and gravel, for a depth of 7.50 meters; plastic clay, 7.50 meters ; quartz sand, 1.50 meters ; plastic clay, 3. 10 meters ; clay, 5.40 meters; marl, 19.40 meters to the chalk. Fiq. 243.— General plan of the foundations of machinery hall. 837 CIVIL ENGINEERING, ETC. ; *. ^ c -i-.u 838 UNIVERSAL EXPOSITION OF 1880 AT PARIS. Made ground. Plastic clay. Quartz sand. Plastic clay. Hard clay. Marl. US et I On account of the differences in the strata it was found necessary to adopt three types of piers according to the thickness of the gravel on which they rested. Whenever the thickness of the alluvial de- posit exceeded 3 meters, the founda- tion of the pier consisted of a block of masonry 7 meters long, 3. 50 wide, and 3.70 thick, resting on a layer of bdton from 0.50 to 0.80 meter thick. (In this first case the resistance of the ground was required to he 3 kilo- grams per square centimeter). This is the general type of foundation, twenty-five piers out of forty being so constructed. When the bed of gravel chalk. rvrtmwi.m r y ym* was reduced in thickness, without fall- fig. 2«. -Geological section. ing below 1.50 meters, the depth and surface of the bdton was considerably augmented, the dimensions be- ing 1.35 meters in thickness, with a surface of 11.20 by 0.50 meters in some instances, supporting a mass of masonry which was the same for all the piers; the resistance in this latter case was 1.0 kilograms. Only five piers were constructed on this type, viz, G, M, P, Q. and P . Finally, for the piers which had to be constructed on the site of the gravel pit, the bed of beton was the same as in the last case, but, before laying this, a group of piles 0.33 meter in diameter and !) meters long was driven into the bed of quartz sand, which extends below the layer of clay 7 meters thick. The foundations on the line A T began on July 5 and presented no difficulty, but in sinking the piers G P portions of the foundations of the exhibitions of 1878 were met and blasted out. Figs. 245 and 246 show a vertical section and plan of one of these piers. Each of these elliptic excavations was 20 by 15 meters at the top, 11.20 by 6.50 meters at the bottom, and from 7 to 7.50 meters deep. The contents varied from 1.100 to 1,200 cubic meters. The piles were sawn off and covered with a layer of bdton, 11.20 by 6.50 by 1.80 meters, amounting to 131 cubic meters. The operation of running in and ramming the bdton occupied 26 men two days. Upon this the various layers of masonry (Fig. 245) were built — varying from 120 to 130 cubic meters — by six or seven masons and as many helpers, in 8 or 9 days. The feet of the principal girders were at the reference 35.12 me- ters.* The masonry was stopped at 32.96 meters to put in the anchor bolts holding the bearings. These bolts are six in number, united by a network of T irons imbedded in the masonry. * Above the level of the sea. CIVIL -ENGINEERING, ETC. 839 Fig. 345.— Foundation of a truss girder; elevation. Each bolt is separated from the masonry by being placed in a cast- iron tube, which allows it 0.03 meter play in every direction. At 840 UNIVERSAL EXPOSITION OF 1889 AT PARIS. 0.50 meter above the reference 32.96 meters each cast-iron tube is prolonged by one of sandstone, so that it may be cut to the exact height of the bearing. The bearing rests upon a large cast-iron bed-plate, so that rubblework under it answers very well. The foundations were completed on December 21 by MM. Manoury, Grouselle & Co., contractors. (372) Principal girders or arched ribs . — Each principal girder is jointed at three points, i. e. at the top, and at the springing lines (Fig. 247). This arrangement simplifies the calculation by determining the exact points of application of the stresses ; it also facilitates the movements due to the variations of temperature, which cause the ridge to rise or fall as the girders expand or contract. We will first consider the arch and afterwards the spandrel, which does not affect its strength, but simply constitutes a filling. The arch is divided into twenty-four panels of different sizes. The dis- tance between the extreme plates of the intrados and extrados at the bottom is 3.70 meters. This distance continues up to purlin No. 5, whence it begins gradually to diminish to nearly 3 meters at the top. This very economical form gives a character of lightness and elegance to the whole girder. As the Figs. 248-254 indicate, the girder consists of two webs 450 by 9 millimeters for the part between panels Nos. 1 to 16; 450 by 10 for that between panels 16 and 21, and 450 by 23 for that between 21 and 24. (Dimensions given in millimeters). These webs are united by plates 770 by 8 for the extrados, and 900 by 10 for the intrados, and four angle irons The uprights and diagonals are fastened to the two webs. For the part between purlin No. 4 and the joint at the foot of the girder the stresses are considerable, and the sections have been strengthened. The covering plates for those parts subject to the greatest stress are six in number. A plate of 10 thick extends over the entire gir- der, a plate of 13 over a shorter length, one plate of 11 over a certain length of the intrados, also two of 12, and one of 13, which makes a total of 71 millimeters. (See Fig. 249). At the extrados, the last two plates are omitted, and they have been replaced by two angle irons which connect the spandrel with the principal girder. (Fig. 252). The portion of the arch between two purlins is formed by three small diagonals and two large ones. This division of the diagonals into small and large serves to decorate the arch, and has also the advantage of giving the same distance, 10.72 meters, between the vertical purlins, which is indispensable considering their great height. 23 S2S H. Ex. 410 — vol. hi — T o face page 840. Fig. 247.— One of the principal tru; i ns irdcrs of machinery hall. ■CIVIL ENGINEERING, ETC, 841 Sections of the great truss girders. Fig. 24?. Fig. 251. 842 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Sections of the great trcss girders. Fig. 253. (373) The diagonals are formed by T -irons of different dimen- sions, according to their position in the section with respect to the webs of 450. From the panel 21 to 12 the diagonals areT-h*ons 200 by 100 14 In the panels 22, 23, 24 they are T-i r o ns 1 4 strengthened by a plate 200 by 10; in the panels 11 to 1 they are 170 by 90 13 CIVIL ENGINEERING, ETC. 843 The panels at the head and foot are of an entirely different con- struction. In those of the head, which have to resist a horizontal thrust of 74,950 kilograms under ordinary circumstances, of 114,300 when the roof is covered with snow, and of 119,840 in case of a wind having a mean velocity of 40 meters per second, two large diagonal double T -irons are used, which take the thrust, and form, with a series of supplementary webs and strengthening plates, a very stiff frame. Figs. 204 and 205 show the method of attaching the bearings to the web of the arch. The bottom panel is entirely plain and has two webs strengthened by several supplementary plates. The panel rests on the upper bearing by means of an additional plate 20 millimeters thick, to which it is fastened by four bolts. The lower pillow block rests on a cast-iron plate, to which it is attached by long anchor-bolts imbedded in masonry, as has been previously described. For facility of transportation the different sections were 5 or 0 meters in length, the joints being made in the middle of a panel, and care taken that the angle irons should break joint. (374) The spandrel has the same construction as the arch itself. It is formed of two webs 400 by 9 united by a plate 770 by 8, and f i • 100 by 100 tour angle irons •- . The uprights are in the prolongations of those of the arch, and like them placed beneath the two webs. The vertical part of the span- drel outside of the girder, which carries the arches of the lateral galleries, and the gutter purlins, is strengthened by two webs 150 by „ i e , . 100 by 100 7 and four angle irons . The joints between the gutter purlins and the girder are made by bolts, on account of the difficulty of riveting at this height, and the gutter is secured to the uprights of this purlin by a number of brackets. All the space below this purlin above the arches of the lateral galleries is closed by a plate-iron curtain 4 millimeters thick formed by plates 1.73 meters long and lapping over each other for a distance of 0.150 meter. (375) Purlins . — There are twelve purlins, including those which support the gutters, which are differently constructed from the others. The two latter are formed of a web 1.05 meters high by 8 millimeters thick, and two plates 300 by 9 millimeters with four angle irons 70 by 70 7 The uprights, consisting of a web and four angle irons, stiffen the beam, and serve at the same time as a support for the rafters on the interior and for the gutter corbels on the exterior. 844 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The other ten purlins (Figs. 255-257) are each formed of an |\J- shaped lattice girder. The tension bars are two flat irons 120 by 8 joined on each side to the two plate webs of 350 millimeters thick. For the two panels near the trusses where the shearing stress is greatest the thickness of the plates is 0 millimeters. The purlins have been calculated by considering them as pieces resting on two supports and carrying three separate loads, viz, the rafters, a portion of sashes and glass, and their own weight. These conditions give a height in the middle of the purlin of 1.80 meters, and this height has been augmented toward each end for architec* tural effect. (370) Rafters . — The purlins are braced by a series of rafters run- ning from the ridge to the gutters (Figs. 258-262). Upon the rafters rest the minor purlins which support sash bars. Rafters Nos. 1 and 2 have been selected as illustrations on account of the peculiar ar- rangement at their upper parts due to the joining of the principal girders. On account of the great length of the purlins it is indispensible that they should be braced at several points; this is accomplished by CIVIL ENGINEERING, ETC. 845 Machinery haij- Rafter. SECTION ' C-D sc*i£ fa' Figs. 258-261. Rafter, rafter end, and sections A B and C D. 846 UNIVERSAL EXPOSITION OF 1889 AT PARIS. means of the three rafters placed between two principal girders. This bracing is made secure by putting at the right of each rafter and for each purlin a large ear of plate and angle irons. Between the two ears a sheet of lead 15 millimeters thick is placed. This arrangement does not prevent the movements due to varia- tions of temperature, for when the girder expands the ridge rises. The lead gives at its lower part and allows the motion. Six bolts are used to unite the two cars, but, in order to leave a slight play, care is taken not to screw up the nuts too tightly. The two ridge purlins support a walking gallery with an outside parapet. This gallery is fixed to the right gutter purlin only, and is free from the other so as to vary its position as the roof moves. (37?) Erection . — The contracts for iron work and the erection of the Machinery Hall were allotted to three companies, viz, the gables and lateral galleries to MM. Baudet, Donon & Co., and the other portions of the great nave were equally divided between the com- panies Fives-Lille and Caile. (378) The method adopted by Fives-Lille Co. is due to M. Lantrac, chief engineer of the company, and was superintended by M. Balme, the resident engineer. This system consisted in putting the parts of the girder together on the ground so as to form four sections, viz, two piers and two arches, then raising these four sections to their proper places, and riveting them together on scaffoldings arranged for the purpose. The scaffoldings required for the whole operation were three in number, one high central one, and two lateral ones; they are shown in Fig. 263; they are mounted on wheels, and are entirely inde- pendent of each other. Description of Fir,. 263. Fig. 203 represents the method of raising the girders, with the traveling scaffold- ings in use. I CIVIL ENGINEERING, ETC. 847 Machinery Hall. Erection op a great truss girder. Method adopted by the Fvies-Lillf. Company. \/ ¥ y \\5 X X Fig. 2S3.— Elevation and plan of girders and scaffolding. 848 UNIVERSAL EXPOSITION OF 1889 AT PARIS. I I', piers; X, high central scaffoldings 22 meters long, 19 meters wide-, -14 meters high, running on 18 wheels 0.80 meter in diameter ; Y Z, two smaller traveling scaffoldings just alike ; U' U 1 , secondary scaffoldings fastened to Y and Z ; V' V', traveling scaffoldings fastened on to Y and Z ; a, a, firmly braced projecting stage ; b, c, hoisting pulleys on a ; d, e, winches for b and c ; f, g, smaller winches below; h, i, small cranes ; j, lifting pulley; k, l, winches ; in, ]>, foot of girder ; x, a platform on piles, with a winch ; n, the rest of the half gir- der; r, guys; w, pulleys; y, traveling crane. When it was desired to transfer UZ and Y from one hay to another, the following operations were necessary: First, a motion at right angles to the axis of the nave for a distance of 17 meters, so as to clear Z and V and allow them to pass under the arched girder; sec- ond, a movement of 21.50 meters parallel to this axis to the following hay; third, a movement at right angles to the axis, so as to bring the whole back into line with its primitive position. These travelers were carried on three sets of rails, two across and one lengthwise, by means of fifty wheels, twenty-eight for the first and third travelers, and twenty-two for the second. The height of the axles of the wheels could be raised enough to enable the wheels to clear the rails, by removing a set of cast-iron bearings placed above the axles for this purpose. In order to pass from one line of rails to another, the travelers were raised by a set of hydraulic jacks, the upper bearings removed, the wheels pushed up and wedged into their frames, and the set of wheels for the other line brought down. The travelers were then moved by cables attached to piles driven into the ground, the cables being wound up on the winches k and 7. The time required to shift X, Y, and Z, was a little less than two days. (379) General process of erection. — The bed plates, cast-iron pillow blocks, were fastened by the anchorage bolts already described. The form is shown in Figs. 264 and 265. The bed plate rests on a sheet of lead 5 millimeters thick, spread upon a coating of Portland cement laid upon the masonry. The portions of one-half of the girder, consisting of the foot, the head panel, and the intermediate sections unriveted, were sent from the shop. The traveling crane y, 10 meters high, was used to handle the dif- ferent pieces, which were put together in two separate portions, m and n, and laid parallel to each other (Fig. 263). Suppose now the bay H H' I I' to be finished ; we pass to the fol- lowing bay thus : X takes the position X, ; Y, the successive position Y, and Y a ; and Z, those of Z, and Z 3 . Then the portion of the girder n placed upon cars running on a cross track is brought to n', directly under the pulleys forming the hoisting apparatus on X, while the foot m is dragged to the position m' just in front of its bearings. Y a is then pushed into the position Y, in line with its CIVIL ENGINEERING, ETC. 849 first position. The same movements are made with Z. The two pieces m' and n' are now ready to he raised. (380) Erection of the foot of the girder.— Fig. 204— The first opera- tion is to turn P around an auxiliary axle, A, until the rounded edge, M, of O bears upon N. S is fixed by four steel wedges, H, to the bed plate T. which is made fast by the anchorage bolts. The auxiliary axle A is a steel cylinder 0. 12 meter in diameter and 0.80 meter long. It rests on the cast-iron half pillow block B bolted to the oak frame E. The half pillow block, C, of the axle A is fixed upon P by bolts and braced by two iron claws, D, riveted to the girder itself. The pieces C and D are subsequently removed and the holes stopped with rivets. When the piece P is dragged over so as to stand exactly in front of R, it is lifted by hydraulic jacks, and the supports are gradually removed until C comes in contact with A. The hoisting was done H. Ex. 410 — vol hi 54 850 UNIVERSAL EXPOSITION OF 1889 AT PARIS. by means of a cable and two pulleys — one fixed to the scaffolding Z, and the other united by an oscillating bar and two connecting rods to a steel axle fixed to the lower flange of the fifth panel (Fig. 2G(>), so that the different pieces could oscillate at right angles to the traction in both directions. The cable was 0.075 meter in diameter and had been tested to 40 tons. The foot weighing 48 tons and bearing partly upon A. its axle of rotation, with three plies of the cable there was no dan- ger of rupture. The cable passed over the winch e and was worked by a gang of twelve men. As an extra precaution the first motion of the girder was aided by the auxiliary hoist q. Two guys steadied p in its motion, and finally the traveler Z was guyed by a steel cable s. It took about three hours to raise both feet to- gether. (381) Erection of the remainder of the girder . — When each foot was raised and secured to its traveler the joining pieces were brought into place by the traveling cranes, h h, and were riveted on the scaffoldings. Fig. 26G.— Special arrangement of the pulleys for lifting the foot of the girder so that the different pieces may oscillate in directions at right angles to each other, in order that the traction shall always be normal to the axis of rotation. Fig. 267. — Scheme adopted by Fives-Lille Co. for erecting the rafters and purlins. The other portion n' of the girder was slung at its extremities to the pulleys d and k by three cables each, so that the section, which weighs CIVIL ENGINEERING, ETC. 851 about 38 tons, Avas borne with perfect security. The inner end was first raised by the winch d until the section took the position to',. It was then raised by means of d and k, to the position to',, the head being about 2 meters from its final position n\. To bring it to the position n\ the winch d was stopped, and a second pulley ir worked by the winch / was attached to the end of girder. Fig. 263 shows the arrangement of these two pulleys. By hauling and slacking alternately with the pulley d, the bearing of the head was brought to the trunnion of the upper joint. The raising of the other section was carried on at the same time until both bearings closed upon the trunnion. When this was done the collar plates were bolted on, uniting the two bearings together. During this time the two sections of the girder were being riveted together. 852 UNIVERSAL EXPOSITION OF 1889 AT PARIS. The operation of raising the whole girder took five hours and a gang of eighty men in all. (382) The raising of the purlins . — After the gutters had been raised and placed by the cranes h and i, purlins Nos. 2, 3, 4 (Fig. 2G7) were raised and placed on U'. The upper extremities were fur- nished with bushings carrying rollers (Figs. 268 and 269). Then the three purlins with their six rafters were riveted together upon the floor of the traveler. The whole system was then rolled by two winches placed on the central traveler and hauled to its final place; the rollers were taken off, the cheeks let down by special jacks arranged on wooden frames; the purlins came into their proper places and were bolted to gussets riveted to the girder (Fig. 270). (383) Weight . — Tons. Weight of each gable-end girder 240 Weight of each of the other girders 196 Weight of one-half bay including the purlins, rafters, and sash bars 62 Weight of gutters, arcade, etc., for one-half bay 28 Number of rivets for the ordinary girders, about 32,000, not in- cluding those for the purlins. Of these 19,600 were driven in the shops, 10,300 on the ground, and 2,100 on the scaffoldings. Number of workmen employed on the ground daily, 250. The first girder was erected April 20, 1888. The first bay was completed in 23 days, the second in 16 days, the third in 12 days, and each of the following bays in about 10 days. (384) Method of erection adopted by Gail & Co . — The system adopted by Cail & Co. was devised by M. Barbet, chief engineer of the company. It consisted in raising the girder in pieces not exceeding 3 tons and riveting them directly from a single scaffold- ing, the top of which conformed as nearly as possible to the intrados of the arch. Fig. 27l shows the elevation of this great scaffolding, consisting of five stagings 16, 18, and 20 meters long, by 8 wide, connected at a height of 10 meters by a series of bridle pieces; the stagings are united at their upper parts by plank floorings; one of the floorings, a flight of steps, follows the outline of the girder which it is intended to support; it has a width of 5 meters; the other, 35 meters high, is horizontal. On this platform, 4 meters wide, two rails, 2.50 meters apart, are laid, which carry a traveling crane, shown in the figure. The five stagings are mounted on twelve wheels 0.60 meter in diameter. The rails, 0.12 meter high, are fixed to strong cross-ties 1.10 meters by 0.25, by 0.15, 0.70 apart and the whole carefully leveled. The scaffolding is moved by five winches set up on its lower fram- ing, and the ropes pass through pulleys made fast to piles driven into the ground. Each staging was provided with a plumb line, and. Fig. 271. Erection of the great truss girders. Method used by Cail & Co. View of the girders and the erecting scaffolding. CIVIL ENGINEERING, ETC. 853 854 UNIVERSAL EXPOSITION OF 1889 AT PARIS, Pio. 272.— Erection of the great truss girders. Method used by Cail & Co. One of the upper platforms of the rolling scaffolding. 855 CIVIL ENGINEERING, ETC. as all the rails were marked in divisions, it was possible to correct, from time to time, irregularities in the motions of the different stagings. The shitting of the scaffolding for one hay occupied not more than 1+ hours. In addition to these scaffoldings there were two large traveling cranes, 8 meters by 6, and 28 high, running on tracks laid outside and parallel to the axis of the nave. (385) Process of erection— After bolting down and adjusting the bed plate, the bearings, etc. , they proceeded to erect the bases of the Fig. 273.— Method of erecting the purlins adopted by Cail & Co. girders by building around the pier a staging which was capable of holding a flooring at any height below the gutters ; pieces, brought by cars, were taken by the cranes, carried up, and fitted ; a gang of riveters followed the fitters as the work went on, to the level of the gutters. The cranes were then moved on to the next pier and the operation repeated. During this time the traveling cranes on the great scaffolding (Fig. 272) raised and placed the other pieces of the arch which were first secured, then bolted together. The two half arches rose pro- gressively together to the upper joint ; at intervals the intrados plate was supported on pairs of jacks, thirty-two for the whole girder, which was thus held a little above its final position so as to leave a little play at the joint. Whom the riveting was finished the half 856 UNIVERSAL EXPOSITION OF 1889 AT PARIS. girders were dropped into their proper position and the connecting collars bolted on. (38G) Erection of the purlins and rafters . — Figure 273 shows the . method by which the purlins and rafters were placed. One end of the purlin was made fast to the chains of the travelling crane, the other end to a rope from sheers erected exactly in line with the defi- nite position of the purlin. The crane was moved out of line as the hoisting went on, until the purlin had cleared the flanges of the girders, the crane was then brought back and the purlin lowered into its place. At the time of lowering the purlin, an aperture was made in the scaffold flooring by taking up some of the planks, which were replaced when the operation was finished. The rafters were raised in a similar manner. To each purlin were fastened six outriggers, coupled at the right of the angle irons fastening the rafters; these outriggers carried pulleys over which ropes passed to winches on the ground. The rafters, like the pur- lins, were raised by these winches. As before stated, there were 32,000 rivets ; of these 4,000 were driven in the workshop, 8,000 on the ground, and 20,000 upon the scaffoldings. The average number of workmen was 215. The first girder and bay were completed on the 24th of May ; the second and third girders and bays required 13 days each ; the fourth and fifth 12 days each, and the rest 10 days each, on an average. A view of the gable in process of construction is given in Plate XIX, and a view of the interior of one end of the hall in Plate XX. (387) The great vestibule . — The central 30-meter gallery communi- cates with the Machinery Hall by a vestibule (Fig. 274), which unites it with the lateral galleries of the great nave. This vestibule has two wings covered by hooded arches 4. GO meters wide, each contain- ing a monumental staircase leading to the Machinery Hall gallery. The iron framework consists of four great pillars 22 meters high, which, by means of four arches, support a belt 25.66 meters in diameter, resting on the middle of each arch. A part of the weight of this belt is borne directly by the pillars by means of struts which form, with the base of the belt, four pendant arches. The roof is a cupola formed by sixteen curved ribs resting, below, on the belt, and converging to’ a second belt 10 meters in diameter, which supports the lantern. The latter also consists of sixteen ribs 0. 15 meter wide, springing from the upper belt and converging to a third belt 1 meter in diameter. The ribs are braced by circular pur- lins, which support the sash bars and that part near the gutters which is covered with zinc. The roof has a double glazed ceiling. A spherical glazed ceiling, hung from the curved ribs by iron rods, extends upward to a perfor- ated circular plate suspended from the lantern ribs, serving as a Paris Exposition of 1889 — Vol. 3. iims v VIEW OF MACHINERY HALL, SHOWINi Civil Engineering, etc — rLATE XIX. mm. WMMM, §jgjSl>3»Thel ; lc conditions. The actual geographical range is mi" ? fOT al ' oWver at 4 50 m «ters above the level of the sea The cost was 474,776 francs. The plans were prepared by MM. Bernard, Chief Engineer, and Andre iinder the threchon of M. Leonce Raynaud, Director of the Eight-House Service. Chapter XL\ III.— Iron light-house at Port Vendres. (307) To facilitate the entrance and exit of steamers plying regu- larly between Port Vendres and Algeria a light-house has been con- structed upon the pier head erected for the protection of this port against heavy seas. 1 On account of local circumstances exceptional difficulties were met with m this construction. On one hand, they were obliged to guard against the consequences of the settling of the foundations of the pier head, which was built on artificial blocks according to the usual process adopted in the Medi- terranean. Again, it was necessary to arrange the edifice so as to lodge the keeper, and to resist the great violence of the waves, for the parapet of the pier head was only 4 meters above the level of low tide, entirely insufficient in great tempests to prevent the waves from breaking over it and striking the light-liouse. Under these circumstances the idea of constructing a masonry light-house was abandoned, as well as one with an iron frame work, on account of the influence of the waves in causing vibrations, and loosening the screws of the tie rods. It was finally decided to build this edifice (Figs. 282 and 283) upon six upright hollow iron pillars 14.50 meters long arranged in the form of a regular hexagon 2.20 meters on each side. Each of these uprights is formed of three parts. The lower part, which has an exterior diameter of 0.30 meter, 0.03 meter thick, is built, for a length of 2 meters, into the mass of the masonry and united by a coupling collar to the middle portion, which has the same diameter and a thickness calculated according to the stress. The upper part is screwed to the middle part, and fastened at its upper extremity to the iron floorings of the platform and the service room. The walls of the latter are formed of plate iron, which completes the bracing. It is cased on the inside with woodwork. The floor and the ceiling are equally of wood. Access to the lantern is ob- 868 UNIVERSAL EXPOSITION OF 1889 AT PARIS. tained by a spiral staircase. The risers are of cast iron, curved, movable around the newel post, and resting on four pieces which allow them to turn easily without the upper risers obstructing the motion. The steps and hand rail are removable ; hence in a threat- ening time they are rapidly taken away, and all the risers are placed according to the direction of the waves so as to avoid almost com- o ' ' 5 ' ' ' io is Metres' Fig. 282.— Iron light-house at Port Vendres. i pletely being struck by the waves. Under these circumstances the risers form a vertical ladder, which also gives access to the chamber and the lantern. Arrangements are made so that the keeper may remain without communication with land during heavy weather. mm. CIVIL ENGINEERING, ETC. 809 For about four years the light-house lias been in regular operation without accident, notwithstanding tempests of exceptional violence during the winter 1887-88, which destroyed a portion of the jetty t — n t T U Fio. 283. — Section and plan of the lodging room of Port Vendres Light -house. and carried away the parapet. Great dashes of spray frequently covered the lantern, put out the fire, and broke the glass in the 870 UNIVERSAL EXPOSITION OF 1889 AT PARIS. keeper’s room. Nevertheless neither the security of the service nor the stability of the construction has been endangered. The results, therefore, may be considered satisfactory in every respect. Cost . — The cost was 59,489 francs. The light-house was planned and erected under the direction of M. Leferme, general inspector, by M. Bourdelles, chief engineer ; M. Barbier & Co. built the iron superstructure. Chapter XLIX — Apparatus, 2.66 meters in interior diameter, CALLED HYPER-RADIANT, FOR LIGHTING CAPE ANTIFER. (398) The apparatus for a light-house, called hyper-radiant, ap- pears in a universal exhibition for the first time. It may not be out of place to call to mind that the first lenticular apparatus which Fresnel made for the light-house at Corduan, in 1822, was a first-class light, having a diameter of 1.84 meters, the same as all those hitherto constructed. And although important improvements have been made in the lenses, yet there has never been hitherto an apparatus constructed of greater diameter. M. Barbier, toward the end of 1885, succeeded in constructing a great annular lens of one-sixth, having a focal length of 1.33 meters and an angular aperture of G5 degrees in the vertical plane. This lens was tried at South Foreland in 1885, and compared with the greatest of the lenses of the first order, and especially with a lens of English construction similar to that of the new Eddystone Light- house, a lens of 0.92 meter focal distance, which occupies equally 60 degrees in the horizontal plane, and subtends an angle of 92 degrees in the vertical plane. Photometric measurements made by Prof. Harold Dixon, of Bal- liol College, Oxford, on the 13th of October, 1885, showed that the illuminating power of the lens of 1.33 meters focal length compared to the Eddystone lens (the two lenses illuminated by the same lamp) was, for the first series of experiments, as 62.2 to 31.8, and for the second series, in the ratio of 28.9 to 13.7. If we consider that the lens of the Eddystone type has an angle of 92 degrees in the vertical plane, while the latter, corresponding to the lens of 1.33 meters, has only 65 degrees, we see that the illuminat- ing power of this last is not simply twice but nearly three times as great. This apparatus was shown in the pavilion of the minister of pub- lic works. (399) Apparatus for Cape Antifer . — The first liyper-radiant appa- ratus to be placed on the French coast will be for the new light-house on Cape Antifer, near Havre (Fig. 284). The optical apparatus which is 2.66 meters in interior diameter, consists of six annular panels each one occupying a sixth of a circumference and including CIVIL ENGINEERING, ETC. 871 twelve lower catadioptric elements, ten upper dioptric intermediate elements, and twenty-six upper catadioptric elements. The optical apparatus is placed on a cast-iron frame formed of six FlQ. 284.— Half elevation, half section, and plan of the hyper radiant apparatus for the new light- house at Cape Antifer, near Havre. columns supporting a circular entablature and a central table which is accessible by a liight of steps. Upon this base a car with conical 872 UNIVERSAL EXPOSITION OF 1889 AT PARIS. steel wheels carries the frame of the apparatus, of which the base is formed by a movable plate with its toothed circumference gearing with the pinion of the driving machine. The clockwork of this machine turns the apparatus completely in 120 seconds, so as to pro- duce flashes every 20 seconds, followed by total eclipses of the light. The machine has an automatic break and an electric .alarm for the slowing and stopping, as well as an arrangement for winding up the weight without interrupting the rotation. This apparatus will presently be described. The cost of the apparatus was 94,000 francs. Chapter L. — Improvements in the apparatus for light-houses USING MINERAL OIL. (400) The reconstruction of the Faraman light-house and the intro- duction into the new edifice of a flashing light of the third class, afforded an opportunity for bringing together the different improve- ments which have recently been introduced into several French light- houses burning mineral oil. These were shown at the exhibition. Multifocal optical apparatus . — It is the general custom to con- struct the dioptric elements of the annular lenses and the cylindrical and vertical elements, employed in the optical apparatus of light- houses, with a common focus. The same rule is applied to the cata- dioptric rings, and there has been hitherto only one exception. This manner of proceeding would be required if the lenses were formed of a single piece, but it can not be justified for those in echelons or steps in use in light-houses, and still less for the catadi- optric rings; for the elements which compose them must be calcu- lated and constructed separately. It is easy to perceive that it does not realize either the maximum useful effect of the light, nor the best distribution of the light upon the surface of the ocean, and that these results can not be obtained except under the condition of assigning to each element a special focus placed in the most favor- able position. By determining thus the different foci of the elements of a cylin- drical lens we find that they should be taken upon the axis of revo- lution above the focus of the central lens and at a height increasing with the distance of the elements from the focal plane of this lens. This method of distributing the foci is not adapted to the annular apparatus the elements of which are obtained by revolution around a horizontal axis; but it is easy to recognize that one may realize the desired effects by taking the foci on this axis, as in the preced- ing case, with this difference: that the elements situated above the central lens have their foci to the left of that of the lens, and the lower elements to the right. In virtue of these arrangements the contiguous edges of two successive rings are formed of two concen- tric circles of the same radius, which come together and unite per- CIVIL ENGINEERING, ETC. 873 fectly witliout either space between or superposition. We thus avoid the defects of the ancient annular pieces of apparatus, at the place of contact of the dioptric elements with the catadioptric rings, which have a distinct focus placed outside of the axis of revolution. Thus multiplicity of foci does not complicate either the calculation or the optical construction, and presents, con- sequently, advantages without any in- convenience. The new apparatus of the Faraman light-house is multifocal. It consists of five panels, each formed of twoun- symmetric lenses, having their princi- pal axes at an angle of 2.‘3 degrees. Its flashes are thus emitted in groups of two. In each group they last a second, and are separated by a little eclipse of two seconds. A great eclipse of six seconds separates each group from that which precedes and follows it. The apparatus revolves once in fifty sec- onds. (401 ) Spherical reflector . — As the Far- aman light illuminates only half of the horizon, it becomes convenient to utilize the light lost on the land side and to send it toward the sea by means of a spherical reflector. But it has not been judged necessary to give to this reflector a radius sensibly equal to that of the lenses as has been hitherto done. It is easy to see that the result to be obtained is independent of this radius, and that one can reduce without incon- venience its length according to the convenience of the service or of the construction. Under these conditions it is easy to make the reflectors of molded, or even of blown, glass with great economy; a slight retouch by grinding, suffices to assure the proper regularity of the in- terior and exterior surface; the latter is then silvered and covered with a protecting varnish. Reflectors Figs. 285 and 286. — Vertical and hori. zontal sections of an apparatus lighted with petroleum oil. 874 UNIVERSAL EXPOSITION OF 1889 AT PARIS. are thus made, at little expense, which utilize about a third of the incident light, and are easily placed in all optical apparatus. (402) Clockwork . — The clockwork and the frame have been the object of various improvements, many of which have been intro- duced in France. Among these we may mention: First. The substitution of conical wheels for spheres, previously used, for the rolling chariot. Second. The winding apparatus for the weight, permitting this weight to be raised without stopping the machine. (403) Automatic brake and regulator . — That the rotation shall be uniform, requires the action of the weight to be always equal to the passive resistances which it has to overcome. When these increase Fig. 287.— Regulating brake and indicator of stoppage. from any cause the apparatus is liable to frequent stoppages. To obviate these we must: First. Give the moving weight an extra load which shall render it capable of putting the machine in motion and overcoming the friction of its parts at the beginning. Second. Counteract, during the motion, the effect of this extra load, which tends to accelerate the velocity. 875 CIVIL ENGINEERING, ETC. The combination lias been realized by means of a conical pendu- lum (Fig. 28 1 ), each arm of which is furnished with a stirrup pierced with a hole, in which a properly balanced rod can slide. This rod carries at its lower part a wooden or a cork button, which rubs upon the interior surface of a spherical segment when the speed of rota- tion brings the arms of the pendulum to their normal distance apart. The friction ceases automatically when the arms approach each other in consequence of the rotation becoming slower or stopping. In the latter case a stop prevents the rod from descending and the center of the segment is situated a little above that of the circum- ference described by the button when the rod rests upon its stop. With this arrangement the surcharge is free if the machine is at rest, and its action determines the motion, which accelerates until the branches of the pendulum have taken their normal distance apart. At this moment the work of the load is equalized by that of the fric- tion, on account of the path which the button describes upon the segment and the pressure exerted by the loaded rod on account of the centrifugal force. The movement then becomes uniform, and the rotation is maintained in the required conditions as long as the passive resistances remain constant. If they diminish slightly the rotation is accelerated, the distance apart of the pendulum balls, as well as the work of the friction increases, and the uniform motion is reestablished. It is the reverse in the case where the resistances increase. The brake works thus as a regulator and has great sensi- bility. It is evident that in varying the load and the path of the rods this arrangement will accommodate itself to all the motions of the clock- work. (404) Electric indicator of the stoppage of the apparatus. — These machines, notwithstanding the intervention of the brake, may. not- withstanding, stop, if the keeper is negligent, and especially if he forgets to wind up the weight at the proper time. It has therefore been considered prudent to signalize such an accident by an electric bell. It is put in motion by the arms of the pendulum when they fall on account of the slowing or stopping of the machine. Their weight then overturns an ebonite box containing mercury. This liquid closes the electric circuit having its two poles in the box. (405) Constant level lamp. — The old lamps have been replaced by lamps on a new model wit li a constant level. They consist of a cyl- indrical copper reservoir furnished at its lower part with a neck which can be opened or shut at will with a cock. A central tube, open at its extremities, passes through the bottom of an upper com- partment of the reservoir, arranged like a tunnel, and descends to the lower part of the neck. Another vertical tube emptying on the exterior of the neck rises to the upper part of the reservoir, with which it communicates. The neck dips into a little tank, from whence starts the feeding tube for the wick and that of the overflow. 876 UNIVERSAL EXPOSITION OF 1889 AT PARIS. To fill the lamp, the cock in the neck is closed and the oil is poured upon the tunnel, and runs into the reservoir hy means of the central tube, driving the air into the lateral tube, whence it escapes into the at- mosphere. When the reservoir is filled the cock is opened, the oil flows into the tank until its level has at- tained the lower orifice of the central tube, that is to say, a constant level. * From this moment the central tube is empty, the lateral tube is full up to the level of the oil in the reservoir, and the lam}) is ready to work. If we open the wick cock it may be lighted. As the oil is consumed its level lowers in the tank and opens the orifice in the central tube by which air escapes, making the requisite quan- tity of oil flow into the tank so as to reestablish the constant level. The lamp is fixed upon one of the uprights of the lantern. It communicates with the wick by means of tubes which pass under the frame and rise in a central column which supports the burner. This ar- rangement makes the service easier, especially for apparatus of small di- mensions, like those of the third class. It avoids all the inconveniences of moderator lamps and properly feeds the wick. Cost . — The expense of the apparatus for the Faraman light-house amounts to 23,300 francs. M. Bourdelles, engineer in chief of the service, made the plan under the direction of M. Emile Bernard, general inspector and director of the liglit-house service. Chapter LI. — Improvements recently made in electric light- houses. (406) Important improvements have been recently made in the electric illumination of the French coast. This illumination is con- fined at present to eight important points, viz, Dunkirk, Calais, *When the lower cock is opened the air in the reservoir is slightly rarified. by the oil passing into the tank. The outer air enters the central tube and clears it, and as the oil rises it is forced up the lateral tube as high as the level of the oil in the reservoir. ^ : Ly ^ O i w Flos. 288 and 289 .— Elevation and plan Of a constant level lamp. CIVIL ENGINEERING, ETC. 877 Gris-Nez, La Canche, La Hbve, Crdach, Les Baleines, and Planier. Five others are in process of erection. Bifocal apparatus. — The small dimensions of the optical apparatus Recent improvements in electric lioht-houses. (0.60 meter in diameter) have been preserved. The apparatus itself consists of annular unsymmetric lenses, preserving the character of 878 UNIVERSAL EXPOSITION OF 1889 AT PARIS. the electric light (flashing with groups of two, three, or four flashes), which is thoroughly appreciated by seamen. This arrangement of the optical apparatus enables the horizontal angle subtended by the lenses to be augmented, consequently the intensity of the light in- creased. (Figs. 290 and 291). The latter is still further increased by the suppression of the horizontal divergence artificially given to the lenses in the vertical elements of the old apparatus. As to the vertical divergence, it has not been thought best to increase it artificially. This bifocal arrangement is the most advantageous and the most appropriate for electric lighting, and it has accordingly been intro- duced into the new apparatus. Caloric engines as motors have been substituted for portable en- gines, three, of 9-horse power, being placed in each light-house. A single one is sufficient in ordinary times, but two are used in case of fog, or to work the fog horns. The third is used as a reserve. The magneto electric machines used are those of M. (le M tritons, which have been entirely satisfactory in all respects. A number of modifications have been introduced, viz : The arrangement of the bobbins. — Eight have been coupled for ten- sion, i. e., one-half in each of the five disks making up a magneto- electric machine. The five half disks are coupled quantitively, so as to divide each machine into two half machines having separately five groups of eight bobbins in tension. Finally, by a commutator arranged for the purpose, two, three, or four half machines may be quantitively combined. On the other hand, it is not necessary to couple two machines when they are in use so as form a single machine. The same result is obtained by leaving them separate and driving them by a single belt. This is accomidished by interposing between the machines a short shaft, the prolongation of those of the machines, carrying two loose pulleys, so that the drivingbelt can be thrown on or off of either. (407) Working of the system. — The system of magneto-electric machines and their accessories allows the variation of the intensity of light according to the condition of the atmosphere. The following table shows the different intensities admitted in the service and the means of obtaining them : Weather Clear. Ordinary. Mist. Fog. Diameter of the carbon points, in millimeters 10 10 20 23 Number of magneto-electro machines in use Mechanical measures: I 1 U 2 Number of revolutions per minute 430 430 430 430 Horse power on shaft (f), circuit closed with the lamp. 2.34 3.80 5.80 7.50 CIVIL ENGINEERING, ETC. 879 Weather Fog. Mist. Electrical measurements: Intensity (I) in ampOres: Circuit closed without the lamp 33 82 150 98 Circuit closed with lamp Electro-motive force (E) in volts: Open circuit Closed with lamp Energy in watts (E I).- Circuit closed with lamp 902 160 350,000 64 3 44 4,312 738 600,000 Photometric measurements: Horizontal intensity (L) of the electric lamp in Carcel burners Intensity of the beam of light emitted measured at a distance of 400 meters 360 500 Efficiency: Carcel burner power per horse power 85.3 6.4 0.77 77.6 Number of burners per ampere 6.5 .54 Ou. O Efficiency / E I \ 0.71 0.78 V 75 g t ) In clear weather, i. e., ten-twelfths of the year, the luminous range of the new electric light exceeds 27 miles, which is amply sufficient. For the other two-twelfths the luminous range is insufficient on ac- count of the fogs, hut it is impossible to remedy this defect without an outlay entirely out of proportion to the results to be attained. (408) Electric regulator.— The electric service as previeusly de- scribed could not employ M. Serrin’s regulators except by modify- ing them and adapting them to the new conditions of electric light- ing. This has been accomplished as follows: The current of a demi-magneto before passing to the lower car- bon point passes through an electro-magnet acting on a rod of soft iron carrying the detent which serves to separate the star wheel from the regulator. This rod is suspended from a horizontal axle around which it can oscillate. It is placed at the proper distance from the poles of an electro-magnet by means of a bent lever driven by a screw and furnished with two spiral springs acting in oppo- site directions. (Fig. 292). With this simple arrangement the variations in the resistance of the voltaic arc and those of the current resulting therefrom deter- mine the oscillation of the soft iron, the escape of the detent, and the proper distance between the two carbon points. It may be noticed also that the new arrangement of escapement is independent of the lower carbon point. When the electric lighting requires more than one demi-magneto, the circuit of the supple- mentary machines is connected directly with the carbon points by means of brushes which allow the motion of the carbon-point holders, and the regulator consequently continues to work under these circumstances as if there was only one demi-magneto acting. 880 UNIVERSAL EXPOSITION OF 1889 AT PARIS. Electric regulators and indicators. A Fig. 292. — Modification of the electric-light regulator. Fig. 293.— Electric indicator of the stoppage or slowing of the machines. 881 CIVIL ENGINEERING, ETC. As to the lighting, it is done hy a hand lever which separates the caibon points the exact distance requisite for the production of the arc light. (409) Controlling apparatus .— The apparatus of an electric light- house is also supplemented by different instruments to indicate the working and make known the defects which may be produced, viz: First. A Siemens electro-dynamometer to measure the intensity of the currents. Second. An electric indicator of the stoppages or slowing of the magneto-electric machines, by means of a bell. This apparatus con- sists of a traveler (Fig. 293) moving by means of centrifugal force* along a fixed rod attached at right angles to the axle of the magneto- electric machine, and which compresses a spiral spring in proportion to the velocity of rotation given to the machine. When the velocity is insufficient the spring brings the moving piece into such a position that it closes the circuit of an electric bell. Third. An electric signal, showing when the light has been extin- guished. This consists of an electro-magnet with its coil in a cir- cuit secondary to that of the regulator. If the light is extinguished the principal current is arrested and the secondary becomes capable of causing, by means of the electro-magnet, the motion of a soft iron rod arranged so as to close the current of an electric bell. (Fig. 294). Fourth. An alarm serves to awaken the keeper when any stoppage of the machines takes place. Cost . — The cost of the various pieces of apparatus, including the optical apparatus, the indicating instruments, three caloric engines, two magneto-electric machines, etc., is 80,000 francs. M. Barbier constructed the optical apparatus ; 301. Sautter, Lemonnier & Co., the motors, and M. Mdritens, the magneto-electric machines, under the direction of 31. Emile Bernard, director of the liglit-liouse service. Chapter LII. — Acoustic signals in connection with elec- tric LIGHT-HOUSES. (410) Programme . — It is proposed to realize in the new establish- ments the following programme: First. To utilize as much as possible the personnel and machinery of the electric light-houses for working the acoustic signals. Second. To arrange all the mechanism so as to produce the sounds when needed. Third. To emit these sounds at a distance from a light-house un- der the most favorable conditions to be heard at sea. Compressed air is used instead of steam, and all the apparatus is united in the same building under one engineer, who takes charge of the electric and the acoustic apparatus, and the three caloric en- gines used to drive the air-compressor. The sirens are operated by compressed air, from a reservoir. H. Ex. 410 — VOL ill 56 UNIVERSAL EXPOSITION OF 1889 AT PARIS. 882 THE ESTABLISHMENT OF THE SOUND SIGNALS IN THE ELECTRIC LIGHT-HOUSE OF BELLE ILE AND BARFLEUR. Fig. 295 shows the arrangement of the machinery in the Belle He light-house. Francs. A, A, A, caloric engines, 9 horse power each 24,000 B, air-compressor, 20 horse power, with water circulation to cool it . 8, 000 C, Holmes siren, with electric- mechanism for the emission and the rythin of the sounds 8, 000 D, D, two reservoirs containing 4.5 cubic meters of compressed air. 6,800 EE, two distributing reservoirs- containing 1.5 cubic meters .... 2, 400 I, motor of one-half horsepower. 1,100 K, Gramme dynamo to work the sirens 1,600 L, shafts, belts, etc 5,400 M, M, M, M, engaging and disen- gaging gear 4, 1(M) P, P, plate iron reservoirs 2,500 R, pipes and valves 2, 900 Sundries % 3, 200 Total 70,000 S, S, electro-magnetic machines. This sum includes much that is required for the light-house itself. The extra expense is about 34,000 francs, without including the cost of erection. The contractors were MM. Saut- ter, Lemon nier & Co., under the direction of M. Bourdelles, chief en- gineer of the light-house service. Chapter LIII. — ' The illumina- tion OF ISOLATED BUOYS AND BEACONS BY MEANS OF GASO- LINE. Fig. 295. — Plan of the establishment in the light-house at Belle lie. (411) It is very important for the security of navigation that there should be some means of lighting economically the beacon towers on isolated reefs. This lias been suc- cessfully accomplished in the fol- lowing manner. CIVIL ENGINEERING, ETC. 883 The apparatus. Fig. 20G consists of four burners placed in the center of a dioptic drum with a fixed light and sheltered by a cylin- drical lantern. This lantern is glazed below for a height correspond- ing to the optical apparatus, and furnished with every arrangement requisite for ventilation and for avoiding the effects of squalls. Its upper part is closed with plate iron riveted to uprights built into the masonry of the tower. A door above the glazing allows the optical appaiatus to be removed, and the burners replaced or repaired. (412) The burners communicate with two reservoirs, each holding 225 liters and intended to contain enough gasoline to last for there months. These reservoirs are placed around the iron lantern, leav- ing two sectors for the service. They are sheltered from the sun, the rain, and the sea, by an iron roof, and a cylindrical cage, supported by a strong steel lattice girder which allows the luminous beams to pass through the openings. The girder is built into the masonry, and the whole construction is sufficiently strong to resist completely the action of the waves. To increase this resistance, the tower is raised as much as possible above the level of the sea, and its diame- ter at the top exceeds by 1 or 2 meters that of the iron superstruc- , ture, which is 2 meters. (413) Properties of petroleum products . — Long experience shows that all petroleum products employed in lighting, produce, by their decomposition by heat, tar deposits, and charcoal, adhering to the orifices of the burners, which, increasing with time, reduce more and more the flow of the fluid, and consequently the intensity of the flame. The amount of these deposits diminishes, and the duration of the light increases, as the product employed is more volatile and ap- proaches the character of the ethers. Again, the luminous intensity diminishes as the essence employed becomes lighter. For these rea- sons, a gasoline weighing G70 grams per liter, perfectly pure and rectified, has been selected. As to the burners, the old type has been kept. They are furnished with a capillary tube giving vent to the gasoline vapor which is projected without pressure upon a metallic spatula upon which the flame rises in the form of a butterfly. This spatula serves, besides, to heat still more the gasoline which comes from the burner. The former passes through a tube communicating with the reservoirs, and is tamped with cotton near the burner. (414) The arrangement of the reservoirs constitutes the most deli- cate portion of the problem. It is necessary to store nearly half a cubic meter of gasoline, to furbish this combustible as it is used, to maintain a constant pressure at the burner in order to have a con- stant combustion, and, finally, to avoid all overflow of an extremely volatile liquid capable of producing an explosive mixture, which might give rise to a serious accident. For this purpose a special contrivance was adopted, namely, a pressure regulator between each 884 UNIVERSAL EXPOSITION OF 1889 AT PARIS. reservoir and the burners which are fed by it. This regulator con- sists of a cylindrical floater which carries, in the direction of its axis, a graduated test-glass containing a calculated quantity of mer- cury, into which a glass tube plunges; this tube has a stopcock and communicates with the reservoir. The iioater rises with a slight play in a receiver united to the burners by means of a tube from the bottom. The reservoir cock being open, the gasoline flows through the tube, fills the test glass, flows into the receiver, and raises the floater. As the hitter rises, the reservoir tube sinks gradually into the mercury and thus reduces the flow of the gasoline until it ceases. Fig. 290.— Section of the apparatus for lighting beacon towers with gasoline. At this moment the level of the liquid attains in the reservoir a height of 0.30 meter above the orifice of the burner, i. e., the most favorable height for the working of the light. Then the burner may be lighted by opening the burner cocks. The gasoline runs from the receiver and lowers the floater until the flow of the reser- voir equals that consumed by the burners. The permanent flow is then established, and the apparatus works automatically with great sensitiveness, and maintains regularity of flow, notwithstanding the 885 CIVIL ENGINEERING, ETC. thermometnc and barometric variations, whatever may be the height oi the gasoline in the reservoirs. Repeated experiments have shown that the arrangements adopted answer perfectly the purpose for which they were established The light has been kept burning one hundred and fifty days and nights without changing the burners. The luminous intensity is equal to that of three Carcel burners for a group of four burners. With the optical apparatus a light is obtained nearly equal to that of the fifth order of Fresnel lights. No accident has thus far occurred, and everything indicates that, with simple precautions, lights may be maintained, at least in the beacon towers. One of these was set up on the beacon tower near Rd Island oppo- site the new port of La Pallice, and a number are in process of erec- tion. (415) Cost.— The cost of the metallic superstructure, including the optical apparatus, the reservoirs, and all accessories, was 7,000 francs. As to the cost of maintenance, it cannot be calculated ' ex- actly; it varies with circumstances; it maybe approximately esti- mated at 1,000 francs per year, as an average. This system of lighting proposed by M. Bourdelle, chief engineer of the light-house service, was constructed by MM. Barbier & Co. Chapter LIV.— Graphic method of quadrature. By M. Ed. Colugnon, Chief Engineer of Roads and Bridges. (416) The following figures, illustrating a new graphical method of quadrature, were exhibited in the pavilion of the ministry of public works. Fig. 297. The quadrature of a plane area may be reduced to the problem of finding the sum of adjoining trapezoids I, II, III (Fig. 297), the bases of which are situated in a right line. This summation is easily made by the following method : 886 UNIVERSAL EXPOSITION OK 1889 AT PARIS. Take the middle points, 1, 2, 3 of the upper sides of the succes- sive trapezoids. Draw the line 1 2; it cuts in a the ordinate sepa- rating the trapezoids I and II. Reverse this line 1 2 end for end. The point « after this reversal takes the position (1 2), defined by its distance 2 (1 2) = 1 a. It is easy to see that the product of the ordi- nate of the point (1 2) by the sum A C of the bases is the measure of the sum of the areas of the two figures I and II. We then join (1 2) and 3, which gives a right line cutting in /i the ordinate separating the surfaces II and III. On reversing end for end the right line (1 2) 3, and taking the segment (1 2) (1 2 3) =3/3; the product of the ordinate of the point (12 3) by the sum A D of the three bases, will be equal to the sum of the surfaces I. II. III. Finally joining (1 2 3) and 4 and taking (1 2 3) (1 2 3 4) = 4 y we obtain a point (1 2 3 4) situated vertically over the middle H of the total base A E, and such that the product H (1 2 3 4) x A E is the sum of the surfaces of the four given trapezoids. The method is general; it applies to the algebraic addition of posi- tive or negative areas, to the evaluation of closed areas, etc. (417) The consideration of zero areas is useful for adding noncon- tiguous trapezoids, and for reducing a rectangle to a given base. First. Suppose (Fig. 298) that we had to add the two figures I and III, separated by a free interval, B C, standing on the same line, A I): we will consider the interval B C as a rectangle II with a height zero, which will make a connection between the surfaces I and III. Applying the method to the three trapezoids I, II, III, we arrive at a final point (1 2 3), and the product (1 2 3) H x A D is the required area. (418) Second. To change a rectangle, A B C D, into an equivalent rectangle, which has for base a given length, A, E. We will con- sider the required rectangle as the sum of the rectangle A B C D (Fig. 299), and a rectangle having zero for height, and B E for base. We therefore take the middle points, 1 and 2, of the upper sides of these rectangles; we join 1 and 2, the line 1 2 cuts in a the ordinate, f i CIVIL ENGINEERING, ETC. 8sr which separates the two surfaces, and taking 1 (1 2) = 2 a, we have at the point (12) the middle of the upper side of the rectangle, A E F G, which has for base A E, and which is equivalent to the given rectangle. The construction avoids the last multiplication which would be necessary to compute the total area. We may take the Fig. 5299. base, A E, so as to render this last operation very rapid. It is suf- ficient to make, for example, A E = 1 meter, or equal 10 meters or 100 meters, etc. (419) The method applies to the computation of the surfaces of cross sections, to the tracing of longitudinal sections along a line, for balancing excavations and embankments, and for the determination of the mean of given numbers without seeking beforehand the total. Fig. 300. Finally, it applies to the quadrature of curves with the same degree of approximation as that given by Simpson’s rule. Divide the base A B of the area to compute into an even number of equal parts, in eight parts, for example (Fig. 300), at the points 1, 2, ... 7; erect ordinates at the points of division, then draw the chords A' m, n m, n p, p B', by joining the successive points of the curve situated upon the even ordinates. Take the points a, b , c, cl, on the deflections of the segments comprised between the curve and the chords at two-thirds of these deflections starting from the chord. UNIVERSAL EXPOSITION OF 1889 AT PARIS. 888 It only remains to join a and b, which gives the point (a b) upon the ordinate (2); to join (a b) and c, which gives the point (o b c) on the ordinate (3); to join (a b e) and d, which gives the point (o b c d) upon the central ordinate of the curve. The required area is the product A B x 4 (abed). 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