346 



ENGINEERING. 



opposite direction. The cable is an inch in 

 diameter and weighs four tons to the mile. 

 The tow-boat has an inverted vertical engine. 

 The clip-wheel, which is situated on one side 

 of the boat, is provided with strong clips or 

 jaws, which automatically seize and hold the 

 cable as it goes over and release it as it passes 

 off. The cable passes over a sheave near the 

 forward end of the boat on emerging from the 

 water, and over another one aft on returning. 

 The cable is held taut and firm against the 

 drum by two wheels on either side, under 

 which it passes before and after being drawn 

 over the driving-wheel. The clip-wheel makes 

 one revolution to eight of the engine. The 

 engine has a 14-inch cylinder and a 16-inch 

 stroke. Four or five loaded canal-boats can be 

 towed by one boat at a speed of three miles an 

 hour. The boats are provided with rudders at 

 either end, and a screw for propelling them 

 through the locks. Ten of these tow-boats have 

 been operating, and it is intended to employ 

 about eighty of them on the canal. The boats 

 are 78 feet 6 inches long and 16 feet wide, 

 and draw, when loaded with their supplies of 

 coal, 5 feet of water. The shaft on which the 

 wheel is turned is about on a level with the 

 deck. By the new system the cost of towing 

 is reduced one half and the time consumed two 

 thirds. This method when completed along 

 the whole line will be of great advantage to 

 eastern shippers to the West, as the boats will 

 return fully laden instead of with only part 

 loads as heretofore, and the freights from New 

 York to Buffalo and the "West will thus be re- 

 duced to merely nominal rates. 



A new mode of street-car traction has been 

 successfully employed in San Francisco for 

 some time past. It is said to have proved 

 satisfactory beyond expectations, and to have 

 shown itself well adopted to all kinds of city 

 traffic, and especially where the surface is so 

 uneven that neither horses nor steam-motors 

 can be economically employed. This is the 

 case with many parts of San Francisco, and 

 led to the development of this novel system in 

 that city, where it has already been adopted 

 by three companies. In a tube just below the 

 surface of the ground an endless wire rope 

 is kept in constant motion by a stationary 

 engine. The tube lies in the middle between 

 the two tracks, and has a narrow slot in its 

 upper side through which the gripping attach- 

 ment that connects the car with the con- 

 stantly moving rope passes; the rope is kept 

 in position in the tube by means of sheaves. 

 Clay Street, in which the system was first 

 employed, is 5,197 feet long, and has a total 

 rise of 367 feet from Kearny to Jones Street, 

 then an equally sharp descent on the other 

 side of the hill, with a slight incline again 

 from Polk Street to Van Ness Avenue. The 

 steepest grade is 1 in 6'15. As on such a hilly 

 route locomotion by horse-power was very 

 expensive, a more economical motive agen- 

 cy was desired ; yet it must be one which did 



not involve the use of a motor which would 

 frighten horses or endanger life. A. S. Halli- 

 die's plan of an endless steel- wire rope was 

 finally adopted. In working out such a scheme 

 very serious mechanical difficulties are pre- 

 sented by the conditions that the rope must be 

 worked below the level of the street, and must 

 be safely covered ; that the cars shall be started 

 smoothly, and instantly brought to a halt at 

 any point of the road ; and that the mechanical 

 apparatus shall be simple and easily controlled. 

 An endless steel-wire rope, 3 inches in circum- 

 ference, 11,000 feet long, and weighing 16,000 

 Ibs., made of 114 wires hardened and tempered, 

 travels up and down Clay Street in two iron 

 tubes, running on sheaves at the bottom of the 

 tube, placed 39 feet apart, with other sheaves 

 projecting from the top, where an upward in- 

 cline requires a guard to keep the rope from 

 rubbing on the roof of the tube, and other 

 larger ones around which the rope passes at 

 every change of angle in the road. At the end 

 of the line the rope passes around a sheave 8 

 feet in diameter, and returns through the other 

 tube. At the engine-house it passes over two 

 angle-sheaves and over the grip-pulleys, also 8 

 feet in diameter. The patent grip-pulleys by 

 means of which the rope is kept in motion are 

 furnished with jaws at their circumference 

 which automatically grip and release the rope 

 as it passes around them, their action being 

 governed by the pressure of the rope upon 

 them. The whole length of the tubes, on one 

 side of the path of the rope on the sheaves, is 

 a thin slot seven eighths of an inch broad. 

 Through this passes an iron bar, which has at 

 its end the gripping apparatus ; this is attached 

 to the dummy which pulls the car, and is fast- 

 ened to the rope by means of a hand- wheel and 

 screw, by which its jaws are made to close 

 over the rope or to release it again. These 

 operations are accomplished by means of a 

 slide working in a standard and actuated by 

 the hand-wheel. This slide has at its lower 

 end a wedge-shaped block, which moves two 

 jaws horizontally. These operate according to 

 the direction in which the slide moves, closing 

 when it is raised and opening again when it is 

 lowered. When the rope is thus gripped it is 

 raised free from the sheaves into the open center 

 of the tube. The grip is so constructed, and the 

 dummy coupled to the car in such a manner, 

 that the impetus of the car when running on a 

 descending grade is not checked by brakes, ex- 

 cept when it is necessary to stop, but the car 

 is held back only by the rope and grip attach- 

 ment ; and so the momentum of the car is 

 utilized to help keep the rope in motion and 

 save power. 



A sudden new start has been taken lately in 

 ocean telegraphy, a branch of enterprise which 

 has remained for five or six years at a stand- 

 still. Three long ocean-cables have recently 

 been or are being submerged by English com- 

 panies in the East, and a transatlantic double 

 line by a French association of capitalists. The 



