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 EARLY TELEGRAPH INSTRUMENTS. 425
mode-the use of the key and wedge, represented in figs. 1
and 4-was objectionable, as it did not firmly close the circuit.
Fig. 3.
It was proposed to use a key-board, represented by figs. 5, 6,
and 7.
Figs. 5 and 6 exhibit views of the keyed correspondent, with
its clockwork. A' represents a top view of it, and B is a side
Fig. 4.
rT; ---
or front view. 1 1 1 1, of both views, represent the long
cylinders of sheet brass, covered with wood or some insulating
substance, except at the black lines, which represent the form
of the letters, made of brass, appearing at the surface of the
cylinder and extending down and soldered to the interior brass
cylinder. A cross section of the cylinder is seen at nD, of which