THE TELEGRAPH 
272 
At stations, crossings, and other places where caution is 
required, as for instance, at the extremities of tunnels, &c., 
there are more complete signals for stopping trains. In 
France* these generally consist of a large disc (fig. 190) placed 
beside the line and made to turn by a lever. 
Every train has to stop when the plane of the disc is turned 
across the line, for that is the signal that the line is blocked. 
Fig. 190. 
When, on the other hand, the plane of the disc is parallel to 
the rails, the train is free to pass on. These discs are large 
enough to be seen even in foggy weather by the engine-drivers 
as they pass, and usually they are visible at a great distance. 
At night a lantern is suspended to the disc, and shows a red 
light to the approaching trains when the line is not clear. 
These signals are placed at some distance from the stations 
* It must be remembered that the railway signals, military telegraphs, &c, 
described in this chapter are those used in France, unless otherwise expressly 
stated.—Tn. 
