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

182 HISTORY OF THE ENGLISH TELEGRAPH.
The apparatus devised by Mr. Cooke to consummate the system of reciprocal telegraphing was simple, and will be understood by studying figures 2, 3, 4, 5, 6, 7, and 8. The whole
are parts of the same combination, and the same letters and
numerals represents the like parts in the different and respective
figures, thus 5 B, represents the same device in fig. 2 that they
do in fig. 6.
The apparatuses represented by these figures constituted Mr.
Cooke's " reciprocal electrometer communicator."
Figure 2 is the near
Fig. 3. station of the reciprocal telegraph, and fig.
1~ 6 the distant station.
The battery is represented at the base of
fig. 2, and upon a
larger scale by fig. 7;
3b, 3bb, are commu8r~ ~B_ __0 h a ^1tating battery pole
BBe < \ c —^-bars, for connecting
Z; 1-the battery with the
conducting or line'W40 8 iwires on the pressure
of the keys-3b is the
copper, and 3bb the zinc poles of the battery 4, 41, are the
telegraph wires, called by Mr. Cooke, the electrometer or reciprocal telegraph wires,
because they were Fig. 4
attached to electro- --
meters at each end.
5B is a complete /'i 4B
set of 26 simple and i —
compound signals.
7b are iron screws 1 B /' 4~l
for steadying the ____t(
needles; 8B are B
communicator keys
for uniting the ends AKp n- -
of the conducting ir - I )
wires with the poles
of the battery, so as ______
to make the current.
pass in either direction through the conducting wires. The battery seen in fig.
2 is represented in larger scale by fig. 7; and, in fig. 8, a top