for this purpose those small apparatus that have been styled semaphore
repeaters.

Mr. Lartigue has invented two automatic apparatus, by means of which
the train itself signals its approach.

1. The first of these, which is generally placed at about 6,000 feet
from the point to be covered, consists (Figs. 5, 6, 7, and 8) of a
very light pedal fixed to the inside of the rail, and acting upon a
mercurial commutator. A spring, R, carried upon the arm, a, of a
lever, A, projects slightly above the level of the rail, while the
other arm, b, carries a commutator.

The spring, R, on being depressed tilts the box containing the
mercury, closes the circuit, and causes an alarm, S, located at the
crossing, to immediately ring. In this alarm (Fig. 8) a piece, P, is
disconnected by the passage of the current into the electro-magnet, E,
which attracts the armature, a, and, a permanent current being set
up, the apparatus operates like an ordinary alarm, until the piece, P,
is placed by hand in its first position again.

2. The second apparatus, exhibited by the Railway Company of the
North, and also the invention of Mr. Lartigue, bears the name of the
"Bellows Pedal." It consists (Figs. 9 and 10) of a pedal, properly so
called, P, placed along the rail, one of its extremities forming a
lever and the other being provided with a counterpoise, C. When a
train passes over the pedal, the arm, B, fixed to its axle, on falling
closes the circuit of an ordinary electrical alarm, and at the same
time the bellows, S, becomes rapidly filled with air, and, after the
passage of the train, is emptied again very slowly under the action of