4i6 



SCIENCE. 



[Vol. XIII. No. 330 



water and coaling stations are unnecessary ; less water is needed, 

 less oil and waste, and from one-half to one-third the quantity of 

 coal, which may be of an inferior quality, costing perhaps one-half 

 of what is now paid. Grades cease to be obstacles, and expensive 

 constructions like that in New York at I loth Street and Eighth 

 Avenue become unnecessary, and stations are made more accessible. 

 It is clear that to stop five-car trains weighing too tons, with 

 engine 23-*- tons (together 123* tons), requires more braking-force 



trains of the Manhattan Elevated Railway of New York City 

 travelled a total of 7,202,966 miles during the year ending Sept. 30, 

 1887, carrying 158,783,241 passengers. The expense of operating 

 the road for the same period was $4,508,467, being 61.89 cents per- 

 train-mile run, or 2.79 cents for each passenger. A carefully pre- 

 pared table of the work done by the cable-road on the New York 

 and Brooklyn bridge for the year ending May 31, 1887, shows a 

 total of 877,496 train-miles run, and 26,388,808 passengers carried- 



^ 



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than the same tram of cable-cars with a lo-ton motor, a total of 

 1 10 tons ; it is also evident that the lighter train will attain full 

 speed more quickly. The horse-power of a locomotive is least at 

 starting, just at the time when the greatest effort is needed ; where- 

 as with the cable-train the motive power (the cable) is already in 

 full speed, with the power of the enormous driving-engines ahead 

 of it. It is a question in cable-traction how to come into full speed 

 slowly enough ; and therefore, to be entirely successful, a cable- 

 road requires the most perfect differential grip. 



The operating expenses were $402,894, being 45.84 cents per train- 

 mile, or 1.52 cents per passenger. In this particular instance it 

 would appear that the cost of carrying each passenger on the cable- 

 road was less than half that on the steam-road, while the cost per 

 train-mile run was at least one-fifth less on the former than on the 

 latter. 



In Fig. I the Rapid Transit Cable Company's motor is seen per- 

 spectively, coupled to a train ; and in Fig. 2 it is represented witb 

 the cab removed. 



iri il— DL 



I) 



As to the amount of power expended in driving the plant, ref- 

 erence is made to Mr. Leverich's paper on the New York and 

 Brooklyn Bridge, wherein it is stated that the highest horse-power 

 developed by the engines was 394.5, and that to drive the plant 

 alone, cable included, required 47.7 horse-power, which gives 87.99 

 per cent to be utilized for cars and passengers. 



A comparison of the motive-power expenses of cable and loco- 

 motive roads may be made from recent reports. According to the 

 report of the railroad commissioners of the State of New York, the 



Fig. 3 is a partial longitudinal section on a broken plane, in 

 which is shown the revolving belt of clips, with inner surfaces of 

 leather, betvi^een which the travelling cable is held ; and the large 

 capstan-wheel for applying and releasing the gripping-jaws, through 

 which the belted clips run (as shown in dotted lines), and are 

 forced with greater or less pressure against the cable, thus retard- 

 ing the belt proportionately from the consequent friction of the 

 outer metallic plates of the clips in contact with the metallic guide 

 and gripping-jaws. This produces a greater or less differential 



