ENGINEERING. 



301 



the construction of a lift at Les Fontinettes. 

 A prospective view uf the completed wurk 

 is given in the illustration. It consists of t\\o 

 immense troughs of plate - iron sections of 

 the canal, they may be termed capable of 

 receiving and floating boats of 300 tons. Each 

 of those troughs rests upon the head of a pis- 

 ton, which work? in the cylinder of a hydraulic 

 These pre>es are in deep wells sunk 

 between the towers in the foreground. The 

 presses are connected by a pipe with a sliding 

 valve, and when this is open a hydrostatic 

 balance is established. If one of the troughs is 

 more heavily loaded than the other, it descends 

 and forces the other to ascend, and the prepon- 

 derance of lifting force may be turned one 

 way or the other by the usual hydrostatic ap- 

 pliances. The stroke of the pistons is equal to 

 the difference between the water-levels, about 

 forty-three feet. The weight of a trough or 

 ''lock-chamber.'' as they are technically called, 

 is 800 tons when full of water. 



Supposing the two lock-chambers to be in 

 position, one at the upper and the other at the 

 lower level : if the communicating valve is 

 opened the upper chamber will descend, and 

 the lower one will rise, and after a few oscil- 

 lations they will stop midway ift equilibrio. 

 To prevent this, the upper chamber is super- 

 charged with a weight of water equal to that 

 contained in a press, so that it continr. 

 motion until it reaches the lower level of the 

 canal. Thus each chamber in alternation lifts 

 the other with the least possible waste of water. 

 The chambers are metallic frames constructed 

 according to the accepted rules of resistances. 

 The presses are the largest in existence. 55 feet 

 high and 61 feet in diameter, and calculated to 

 resist an internal pressure of 27 atmospheres. 

 There were no precedents, as smaller cast-iron 

 presses had collapsed under less strain. It was 

 therefore decided to use rolled-steel rings super- 

 posed and set in a groove to prevent lateral 

 movement. To secure absolute tightne- 

 compound cylinder thus formed was lined with 

 copper in a single sheet ^ of an inch thick. 

 An experimental section constructed on this 

 principle sustained a pressure of 175 atmos- 

 pheres without distortion. 



The passage of a boat, which formerly required 

 two hours, is now effected in three minutes. 

 The apparatus is the largest of the kind in 

 existence, and reflects much credit upon Mr. A. 

 Barbet. the engineer of the contracting estab- 

 lishment. A similar lift has more recently been 

 completed in Belciutn. 



Dorks at Havre. The Bellot BaMn. the latest 

 artificial improvement to the important French 

 port of Havre, is constructed upon made land 

 southward of the Tnncarville Canal. It is 

 bounded on the south by a masonry dike 

 3.2-" feet in length and a'stockade 1,790 feet 

 in extent. Its total length, including that of 

 the entrance-lock, is 3.762 feet. Its two di- 

 vi> ; ons are known as the east and west docks, 

 which are of unequal length, but of a uniform 



width of 720 feet. The total area of the dock 

 l-i'-u s jiiare yards. The entrance-lock is 

 t wide and is provided with tide-_ 

 the leaves of which are of rolled iron, 54 feet 

 wide and 36 feet high, arranged with air and 

 water chambers, so that the weight upon the 

 h : .m.-es can be varied between the extremes of 

 25 tons and 155 tuns. The sluiceways, also 98 

 feet wide, are spanned by revolving bridges 

 operated by powerful hydraulic machinery, as 

 are also the gates, sluiceways, and capstans of 

 the whole basin. 



The construction of the beton work was very 

 difficult, owing to the exposed nature of the 

 shore, liable to be swept by severe storms. 

 The excavations had to be kept dry by pump- 

 ing at every rise of the tide, and in some 

 the pumps had to be hoisted as the tide rose. 

 The blocks used for the foundations were 22 

 feet wide by 33 feet long, each with a central 

 aperture, to allow excavation from within the 

 block. Thirty days were allowed for the set- 

 ting of the beton. When the masonry w;;s 

 complete the central space was filled in with 

 beton. A barge carrying a boiler, which fur- 

 nished steam for the pumping machinery, wiis 

 moored between two of the blocks, so that the 

 pumping was effected with great rapidity. By 

 this process 87 blocks were sunk, representing 

 '00 cubic feet. 



Donble-euder Screw Ferry-Boat. The use of 

 the double-ender paddle-wheel ferry-boat has 

 been carried to greater perfection in America 

 than elsewhere. Indeed, it is only recently 

 that they have been at all used abroad. A new 

 type of boat has recently been launched at 

 New burg, N. Y., for use on the New York and 

 Hoboken Ferry. She is a double-ender, with 

 a screw at each end. The shaft runs the entire 

 length of the boat, and the screws always ro- 

 tate together, being incapable of independent 

 movement. 



Many advantages are claimed for this system. 

 All the machinery is below decks, enlarging 

 the deck-room about 20 per cent. The ai 

 of paddle-wheels, of course, largely in<-: 

 the cabin-room. The engines are of the ordi- 

 nary triple- expansion type, but the crank-pins 

 are of uniform diameter, because the engine 

 will be worked in one direction quite as much 

 as in the other. For the same reason the 

 screw-propeller blades have both faces alike, 

 since they will be required to work both ways. 

 One of the obstacles to ferry-boat navigation 

 is the liability of the slips to become filled with 

 ice. Ordinary tug- boats have been found very 

 effectual in clearing the slips by simply revolv- 

 ing their screws. Paddle-wheels have merely 

 a surface effect. It is thought, therefore, that 

 the new type of boat will be able to ckar 

 ferry-slips of ice with great ease. It has been 

 suggested by Capt. Zalinsky. inventor of the 

 dynamite gun. that the ordinary type of ferry- 

 boat could be easily made available for harbor 

 defense by mounting pneumatic guns upon 

 them. It is evident that a vessel of the type of 



