MEANS OF COMMUNICATION. 33 
If the inclined plane has only a single track, as seen in pl. 4, fig. 7, turn- 
outs must be’ arranged at the top, the middle, and foot of the plane, that 
the ascending and descending cars may cross each other. When loaded 
cars are to ascend the plane the end of the rope is attached to them, the 
drum is turned, and as the rope is wound upon it the cars ascend. 
' When cars are to descend the plane, whether they be loaded or empty, 
they are in like manner attached to the rope and suffered to descend, the 
drum being uncoupled from the engine and the motion regulated by the 
brake. 
When the inclined. plane has a double track, as is necessary upon roads 
where there is a great deal of travel, two drums are required, the one for 
the ascending trains, the other for those descending. The arrangement of 
the tracks is the same as for self-acting planes. 
Where the plane has so little inclination that the descending cars cannot 
move the heavy cable, it becomes necessary to attach a second rope to the 
foremost of the descending cars, while the other end, after passing over a 
roller at the foot of the ramp, is secured to the last of the ascending cars, 
and thus the engine carries the ascending cars up, and the descending ones 
down. | 
A similar plan is adopted upon the inclined plane in the great Liverpool 
tunnel, to move the cars in each direction (jig. 12). An endless cable passes 
first around the vertical drum, a, which has two grooves upon its surface, 
thence diagonally to a smaller drum, a, then half round the pulley, ¢, past 
the pulley, a, again, and diagonally across to the lower groove in the pulley 
A, thence along the centre of one of the tracks, over the large wheel, 3, and 
along the centre of the other track again. 
The cable, by the hygrometric changes of the atmosphere, is lable to 
contraction and expansion, to compensate for which, and to keep it con- 
stantly tightened, the roller, e,is placed upon a carriage running on rails, 
which is drawn back by a heavy weight, the suspending cord of which passes 
over the pulley, d, and thus the cable is kept uniformly tight through all 
weathers, moist and dry. 
A steam-engine at the top of the ramp gives motion to the drum a, and 
the cable receives a constant motion up one track and down the other. The 
ears are attached to the cables by smaller ropes. 
Ina simifar manner a line of horizontal road may be worked with station- 
ary engines. 
The road is divided into distances of 500 to 600 rods, and at the termina- 
tion of each stretch there are a double track and a stationary engine. The 
drums at the stations a Bc (jig. 11) are run alternately first in one 
direction, then in the other. pb and £ are the trains drawn in the direction 
of their arrows by the cables 2 and #, upon the drums o and g, and 
dragging after them the cables 7 and g from the drums m and n, which are 
uncoupled from their respective engines a and B. 
Instead of running the two drums of each machine one after the other, 
they may be run at the same time, but then a double track with crossings 
becomes necessary, as seen in jig. 10. 
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