494
EXPOSITION AT VIENNA.
lowing index-plate. The numbers denote the manipulating levers : —
Up-Track Signals.
Main Up.
Main
Down.
Down-Track Signals.
Distance.
Switch.
Branch
Branch
Switch.
Branch.
Main.
Main.
Branch.
Up.
Down.
Branch.
Main.
Distance.
1
2
3
4
5
6
7
, 8
9
Those from 1 to 4 and 7 to 9 are to move semaphores, while 5 and 6 are for the two switches. In Figure 2, Plate I., a cross-section of the stand of levers is shown to one looking from one end of the cabin. When any signal is to be given, one or more of the levers must be pulled forward into the positions represented by the dotted lines. The same kind of spring-catch which is used to hold the reversing lever of a locomotive fastens each of these levers when in its proper position. The levers move on a shaft under the floor. Each one divides into two arms, one of which, as D, communicates by rods to a switch or semaphore; the other carries a counterpoise, E. There are two sliding bars above the floor and six beneath, which act like the tumblers of a lock when laid horizontally, a longitudinal motion being given them by suitable connections with the manipulating levers, as at A, B, and C. The purpose of these bars is to prevent the movement of certain levers while others are drawn forward. The general principle upon which all are constructed is made evident by the drawing (Fig. 4, PI. I.) of one of the two bars above the floor. It is evident that in Figure 4 the levers 1 and 4 are locked, and 2, 3, 5, 6, 7, 8, 9, can be moved.
The operation of the apparatus is as follows : When the levers stand vertically, that is, in their normal position, the main up track and the branch down are open and free; but the semaphores all stand at "danger.” If, now, a train is coming up on the main track, the signal-man w 7 ill pull forward levers 2 and 3, which raise the semaphores (at 2, 3,