the rib by 1-inch pins at intervals of 5 feet, and to the angle-iron stringer beams, which carry the roadway. The roadway consists of corrugated flooring plates inch thick, 3 inches deep, and 1 foot pitch. The plates are covered with concrete of cement and granite chippings, and

Hydraulic Canal Lift at Les Fontinettes, France.On the 8th of July took place the official ceremonies attending the opening of this magnificent work near St. Omer on the Neuf-Fossé Canal, which connects the ports of Calais, Gravelines, and Dunkerque with the canal system to

as the first part of the roadway is necessarily rather steep, it is stepped out into 2-feet-6inches treads, with a 3-inch rise. The stringer beams, to which the flooring plates are riveted, are of angle irons 6 inches by 3 inches by inch, bent to a radius of 114 feet, having a versed sine of 11 feet 6 inches; and an ornamental rolled iron is riveted to each with countersunk rivets. Two ornamental cast iron pillars are fixed at each approach, and termi

the southward. It was begun by Louis XIV, and all the barge traffic from the ports in the vicinity of Calais, are obliged to pass through this section on their way to Paris or Lisle. The annual traffic amounts to 800,000 tons, and will become greater with increased facilities. Hitherto the change of level at Les Fontinettes has been overcome by means of locks, and boats were often detained for several days awaiting their turn. While contemplating the construc

the construction of a lift at Les Fontinettes. A prospective view of the completed work is given in the illustration. It consists of two immense troughs of plate - iron-sections of the canal, they may be termed-capable of receiving and floating boats of 300 tons. Each of these troughs rests upon the head of a piston, which works in the cylinder of a hydraulic press. These presses 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 preponderance of lifting force may be turned one way or the other by the usual hydrostatic appliances. 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 oscillations they will stop midway in equilibrio. To prevent this, the upper chamber is supercharged with a weight of water equal to that contained in a press, so that it continues its motion until it reaches the lower level of the canal. Thus each chain ber 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 63 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 superposed and set in a groove to prevent lateral movement. To secure absolute tightness the 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 atmospheres 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 establishment. A similar lift has more recently been completed in Belgium.

Docks at Havre.-The Bellot Basin, the latest artificial improvement to the important French port of Havre, is constructed upon made land southward of the Tancarville Canal. It is bounded on the south by a masonry dike 3,280 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 divisions 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 is 253,460 square yards. The entrance-lock is 98 feet wide and is provided with tide-gates, 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 hinges can be varied between the extremes of 25 tons and 155 tons. 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 pumping at every rise of the tide, and in some cases 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 setting of the beton. When the masonry was complete the central space was filled in with beton. A barge carrying a boiler, which furnished steam for the pumping machinery, was moored between two of the blocks, so that the pumping was effected with great rapidity. By this process 87 blocks were sunk, representing 1,575,000 cubic feet.

Double-ender 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 Newburg, 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 rotate 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 absence of paddle-wheels, of course, largely increases the cabin-room. The engines are of the ordinary 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 clear ferry-slips of ice with great ease. It has been suggested by Capt. Zalinsky, inventor of the dynamite gun, that the ordinary type of ferryboat could be easily made available for harbor defense by mounting pneumatic guns upon them. It is evident that a vessel of the type of

the "Bergen," as the new boat is named, would have many advantages over side-wheelers for war service, since her screws and the most vulnerable parts of her machinery are under water. The " Bergen's" builders are Thomas C. Marvel & Sons, of Newburg, N. Y. Ferry at Greenwich, England. More than two centuries and a half have passed since a ferry was first established at Greenwich, on the Thames, below London, but no attempt has been made until the present year to introduce modern methods. The peculiar difficulties of the situation include a sloping river-bottom and a tidal rise and fall of 20 feet. At high water, therefore, the boat can land at the bulkhead line, but at low tide she can not approach it within three or four times her length. To overcome this, an inclined railway, 348 feet long, has been laid on the bottom, the whole securely bedded in concrete. Up and down this incline a landing-stage is moved by means of suitable machinery, and two platforms are made to travel back and forth between the land ward side of the stage and the wharf, whatever the distance may be. "On each side of the river," says London "Engineering," in a detailed description of this ferry, "close behind the abutment, two cast-iron cylinders are sunk close to each other to a depth of 145 feet below the level of the roadway. The cylinders are 10 feet diameter on top, increasing in size by varying cones to 11 feet 6 inches in diameter at the bottom. The metal varies in thickness from inch to 1 inch. The contractor for this work, with fine old English crusted conservatism, is doing the sinking of the cylinders with divers, so that it is at once evident that speed of sinking and cost are matters of comparatively smali importance.

"The cylinders are for the purpose of wells, in which weights will be worked to act as counterpoises to the traveling carriages and landing-stage. Sufficient engine - power has been provided to overcome the inertia in moving these platforms, and also any additional weight of traffic which they may carry. As the slope on which they travel is 1 in 10, one tenth of the weight in the wells will balance that of the platforms and landing-stage."

It seems well nigh incredible that such primitive methods of propulsion should be used in the greatest capital of the world, and there is no obvious reason why the double-ended American ferry-boat system should not have been used to advantage in dredged ferry-slips, instead of the comparatively complicated stages and platforms here described.

Moving the Brighton-Beach Hotel.-During the winter of 1887-'88 the ocean made such encroachments along the beach of Coney Island that the foundations of the Brighton-Beach Hotel were undermined and the entire basement story was washed away. The most approved devices were tried in vain to prevent the inroads of the sea, and the hotel proprietors finally decided to move the building back

six hundred feet to a place of safety, a work of no small magnitude, since the building, a wooden structure, was 465 feet long, 150 feet deep, and three stories high. The estimated weight was 5,000 tons. The contract was awarded to B. C. Miller & Son, of Brooklyn, who agreed to do the work for $12,000.

The first operation was to lay twenty-four parallel tracks underneath the building and extending landward about three hundred feet. A mile and a half of rails and 10,000 ties were used, the ties resting upon planks. The building was then jacked up, and 112 ordinary platform cars, hired for the purpose, were rolled under the building, having transverse timbers laid across them for the sills to rest upon. A twenty-foot section of the hotel was raised enough to admit the passage of the cars with an inch or two to spare, and when the car was in place the section was lowered, care being taken to adjust the bearing so as to secure as even a distribution of weight as possible. The cars were jacked apart before the weight was allowed to settle upon them. Heavy tackleblocks and falls were next attached to the twenty-four lines of cars upon which the bridge finally rested, and the running parts were attached, as shown in the illustration, to locomotives, some of the falls crossing one another, so that each gang of locomotives had its pulling-strain distributed over more than half of the building.

On April 3 the ropes were tightened for the first time, and the building was moved a short distance without difficulty. The next day, with four locomotives, it was moved to the end of the rails. The track already passed over was then taken up and moved in front of the locomotives and the rest of the journey completed without the least difficulty. Probably it is the most considerable feat of house-moving ever undertaken.

Harbor Improvement.--Commercially speaking, one of the most important works recently undertaken by the United States Government is the deepening of the channel in New York harbor. In view of the greater length and deeper draft of ocean steamers, it has become necessary to deepen the channels, and at the same time to straighten them, because quick turns are impossible for very long ships. Large steamers are obliged to fix their hours of sailing so as to reach the bar at high tide, and inward bound vessels are frequently obliged to anchor outside and wait for high water. In 1884 an appropriation of $200,000 was made by Congress for the improvement of Gedney's channel, and Col. G. L. Gillespie, of the United States Corps of Engineers, was directed to make a survey with a view to determining the best course of procedure. The result of careful soundings showed that no shoaling whatever had taken place since the first accurate coast survey of 1835, a channel twenty-three feet deep having been maintained by the natural scour of the tides. It was held, therefore, that