The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

THE TELEGRAPH APPARATUS. 315
extremity L1, a rod with a hook tl, which engages in the teeth
of a little steel-toothed wheel r; the ratchet in descending makes
this wheel turn one tooth; when rising, on the contrary, it
slides upon the inclined plane of the succeeding tooth, and engages itself above it, in order to make it descend in its turn.
A second hook, t,, borne by the plate pi, prevents the toothed
wheel from turning back during the ascending movement of
the rod t1; a steel needle or indicator o, fig. 1, and o i, fig. 3,
borne by the axis of the toothed wheel r,, turns with it upon
the circular dial of the keys, fig. 3, and passes successively
before the telegraphic letters or signals written or printed on
the keys of fig. 2. It will be seen, therefore, that whenever
the current is interrupted, the lever I detaches the armature,
and makes it descend; the hook-rod L1 t lowers a tooth, makes
the indicator advance one step, and brings it from one letter to
a succeeding letter. The most essential part of this instrument has been called, by Messrs. Seimens and Halskie, the
Fig. 2. Fig. 3.
" shuttle," because it is similar in effect to a weaver's shuttle,
moving continually from right to left, and from left to right,
closing and opening the circuit, and giving also to the armature a continuous movement. The shuttle n nl, scarcely perceptible in the drawing, is thus composed; upon the support
s3, is raised a little brass column, bearing on its upper part the
little, elongated, rectangle n n, of copper, furnished with two
right-angled appendages, with sockets a al, and very easily
moved; this is the " shuttle."
At each of the extremities of the appendages a a,, and perpendicular to the surface of the shuttle, is fixed a little piece of
copper, pointed upward, and represented by the dotted lines on
the faces n n,. Underneath the extremity nl, is a little foot,
which has a to-and-fro movement, with the shuttle around the
centre n,, and rests at the bottom upon a little projecting
metallic band. The shuttle, consequently, oscillates horizon