November 5, 1886.] 



SCIElsrCE. 



417 



points where steep grades are crossed by level 

 streets, carried around curves by guide-rollers, 

 and kept in motion by a steam-engine located at 

 any convenient point on the line of the road. A 

 gripping device at the end of a thin vertical steel 

 plate, or combination of plates, connected with 

 the car and passing through the slot in the tube, 

 transmits the motion of the cable to the car, the 

 speed of the car being determined by the speed of 

 the cable, and usually not exceeding about eight 

 miles per hour in city streets. The action of the 

 grip is controlled by a grip-man, who, by the 

 movement of a lever or hand-wheel, can start or 

 stop the car as gently or as suddenly as may be 

 desired. Fig. 1 is a longitudinal section of the 

 slotted tube in use on the Clay Street hill road. 

 At the extreme left are shown the depression pul- 

 leys at the intersection of a level cross-street with 

 an ascending grade. The weight of the car on 

 the grip keeps the latter sufficiently depressed at 

 such points to clear the pulleys. At the right is 

 shown a supporting pulley. A transverse section 

 of the tube, with its surrounding framework, 

 which supports the rails, is shown in fig. 2. The 

 gripping device in use on the Clay Street road is 

 shown in fig. 3, and its operating mechanism and 

 supporting framework are shown in fig. 4. The 

 gripping- jaws, which close on the rope between 

 the pairs of guide-sheaves, are moved by the up- 

 per hand- wheel, while the grip may be raised or 

 lowered bodily by the lower wheel. The guide- 

 sheaves, which are kept in contact with the cable 

 by springs when the gripping-jaws are released, 

 guide the cable smoothly between the jaws when 

 the car is not in motion, holding it in position for 

 gripping when it is desired to start the car. Many 

 modifications of the grip have been devised, in 

 most of which the jaws move vertically instead 

 of horizontally ; but with the exception of the 

 Paine grip, used on the East River bridge, the 

 essential features in all are the same, and they 

 differ only in detail from a grip described and 

 illustrated in a technical journal nearly fifty years 

 ago. Figs, 5 and 6 show two varieties of lever- 

 grip now used on many roads. 



As frequent and careful inspections of cables 

 and machinery are required, and as on many roads 

 cars are run continuously night and day, a dupli- 

 cate or duplex system has been found necessary, 

 of which the Tenth Avenue line in this city may 

 serve as an example. In this system two cables 

 run side by side through the tube, each supported 

 by a separate set of pulleys, and provided with a 

 separate engine. While one cable is running, the 

 other is held in reserve ; and, in case of accident 

 to one cable or engine, the other may be immedi- 

 ately started up, the grips, which are made 



double for the purpose, releasing one cable and 

 taking up the other. The engine-room of the 

 Tenth Avenue line is shown in fig. 7, and the ar- 

 rangement of duplex cables and pulleys may be 

 seen in fig. 8. The cables may be run alternately, 

 and for any desirable length of time, giving ample 



Fig. 6. 



opportunity for inspection and repair without 

 interruption of travel. As will be seen in the en- 

 graving, there are two complete plants of machine- 

 ry ; and as they are duplicates, a description of 

 one will suffice for both. The motive power for 

 each plant is a Wright automatic cut-off engine 

 of three hundred horse-power. A six-foot wheel 

 on the engine-shaft gears into a thirteen-foot 



