240 



ENGINEERING. 



have increased the weight to 1,228 tons. The 

 new wooden structure, which has replaced 

 it, is estimated to weigh 1,050 tons. A de- 

 vice is applied in the new superstructure for 

 the automatic regulation of the continuous iron 

 truss which is required to render the stays from 

 the tops of the towers to the floors effective. 

 It is necessary that the different points of this 

 truss should remain as nearly as possible abso- 

 lutely in the same position. The automatic 

 adjustment by which the middle point of the 

 continuous truss is kept from shifting at any 

 moment toward either end, is effected by 

 means of an iron rod stretching along the 

 lower chord from one end of the bridge to the 

 other. The rod is attached at each end to the 

 short arm of a bent lever, at the other arm of 

 which is suspended a narrow wedge. The 

 wedge is held between the end of the chord 

 and the abutment. The iron rod has the same 

 measure of expansion and contraction as the 

 chord, and the lever is so constructed that the 

 wedge will be raised or lowered by the press- 

 ure or relaxation of the rod at each change in 

 temperature, so that it will just fit in the space 

 between the abutment and the chord of the 

 truss, thus keeping the center of the truss ab- 

 solutely stationary and the chord constantly 

 rigid, while leaving full play for the elongations 

 and contractions caused by changes in tem- 

 perature. 



A new iron light-house in Chesapeake Bay, 

 off Cape Henry, is one of the finest structures 

 of the kind. From base to top the height is 

 155 feet, the diameter at the base 30 feet, and 

 at top 16 feet. There are six stories before 

 reaching the service, watch, and lantern rooms 

 and the roof. The total weight of materials 

 is 1,700,000 pounds, 7,000 pounds of bolts be- 

 ing used in joining the parts. The structure 

 has an octagonal frame of cast-iron and an in- 

 terior of sheet-iron, cylindrical in shape. The 

 castings of the base and first story are 2 inches 

 in thickness. The sheet-iron lining is f inch 

 thick. The iron staircase goes around the 

 cylinder. The light-chamber is a circular steel 

 frame 12 feet in diameter and 9 feet high. 

 The different stories are bolted together 

 through the cast-iron floor-plates, which are 

 !$ inch thick. 



A larger proportion of the ships built on the 

 Clyde in 1881 were made of steel than in for- 

 mer years. The year was one of remarkable 

 activity. No fewer than 261 vessels were 

 launched, with an aggregate capacity of 341,- 

 022 tons. In 1880, which showed the largest 

 construction of any year since 1874, the ton- 

 nage reached 248,800. The number of con- 

 tracts on hand gave indications of a still larger 

 construction in 1882. 



Professor Raoul Pictet, of Geneva, has been 

 experimenting on an improved model for naval 

 construction. He has worked out a design 

 which differs essentially from the present type 

 of hull, and which in the model promises per- 

 formances in. speed far better than the best- 



designed vessels are now capable of showing. 

 He expects to attain a speed of thirty to thirty- 

 six miles an hour. The advantage consists in 

 such an arrangement of the keel as to diminish 

 the resistance of the water to the lowest point. 

 As the speed increases, the prow ri?es up, and 

 only the sides of the hull and the portion in 

 the vicinity of the wheel are subject to fric- 

 tion, so that the ship will glide over the water, 

 instead of having to push its way through the 

 water. 



A new system of mountain-railroad has been 

 invented by a French engineer, M. L. Edoux. 

 It is being employed to establish communica- 

 tion between the watering-place of Cauterets 

 and the baths of La Raillere, whose hot sul- 

 phur-springs are much visited by invalids. 

 The springs are not quite a mile distant from 

 Cauterets, and four hundred feet higher. The 

 principle of the hydraulic elevator which is 

 used in buildings is utilized, a mountain cata- 

 ract furnishing the motive power. The car 

 conveying the passengers is raised by five hy- 

 draulic elevators placed in towers some forty 

 yards apart, each separate lift being eighty- 

 four vertical feet. The top of each tower is a 

 little higher than the foot of the next one, with 

 which it is connected by an inclined bridge, 

 along which the car is carried by gravity to 

 the platform of the next elevator. The car 

 descends to the station from the top of the 

 highest tower, stopping on a platform which 

 transfers it to the return-track by an automatic 

 arrangement controlled by a hydraulic piston. 

 The downward track winds around the side 

 of the mountain at a very slight inclination, 

 and ends at the second tower from the foot. 

 The last two stages the car descends by means 

 of elevators in the two lower towers and a 

 connecting inclined track. 



The inclined railway at the Giessbach, on 

 the Lake of Brienz in Switzerland, is an appli- 

 cation of the water-balance system. A de- 

 scending carriage is made to draw up a second 

 loaded one by means of a steel-wire rope con- 

 necting the two and passing over a reversing 

 pulley at the summit, and of an excess of weight 

 obtained from a load of water carried in a cis- 

 tern in the under-frame. The length of the 

 line is 1,100 feet, the height of the lift 303 

 feet, the average gradient 28 in 100. The car 

 can carry forty passengers and luggage. It is 

 provided with a toothed wheel and safety- 

 drum. There is but one track, with double 

 rails at the crossing point, the cars being able 

 to turn out without switching from the fact 

 that the wheels of one are flanged on the in- 

 side, and those of the other on the outside, of 

 the rail. The weight of the car empty is 5'3 

 tons ; loaded, it is from 6 to 9 tons, demanding 

 a counterpoise of from 7'3 to 10'8 tons, requir- 

 ing from 1*6 to 5'8 tons of water in the cistern. 

 The maximum speed allowed by the charter is 

 only one metre per second. About one half of 

 its length the track is carried on a wrought-iron 

 bridge of arched trusses. 



