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

322 SEIMENS AND HALSKIE S GERMANIC TELEGRAPH.
continue to remain motionless. To completely establish the
correspondence, the operator of station 2, being notified by the
alarum, withdraws his bell apparatus from the circuit, and puts
in its place the telegraph and the battery. The telegraph apparatuses then immediately work together. This simultaneousness of movement will not take place if the operator of station
1, in giving the alarum, has not first introduced his telegraph
into the circuit, and if his telegraph has not rested motionless
while the bell of the other station is sounded.
If the operator of the second station wishes, in his turn, to
correspond, or express some doubt, or ask some explanation, he
places his finger upon a key, the needle of station 1 stops upon
the signal corresponding to that key, and the sender of the dispatch is thereby notified that the operator of the other station
wishes to speak. The interview then takes place, the explanations are exchanged, and the transmission of the signals is then
resumed.
The normal movement of this telegraph is that whenever
the needle passes over a demi-circumference of the dial. By
this system, fifteen signals can be transmitted in a second.
This rapidity is ordinarily attained. A Daniel battery, of five
pairs, is sufficient to work a line of from one to two hundred
miles. A battery of twenty-five pairs, with subterranean
wires, makes the apparatus work very well over two hundred
and fifty miles.
THE TRANSMITTER AND ITS APPLICATION.
To avoid increasing the number of pairs, an apparatus has
been added to the Germanic telegraph, by the inventors, called
a " transmitter," which is a peculiar relay magnet. When the
circuit is closed, the current from the batteries of the stations
do not enter at first into the two spools of the electro-magnets of
the two stations. It passes first into the spools or coils of the
transmitter, opposite the poles of which the armature turns,
similar to those of the telegraph and of the bell apparatus. As
soon as the armatures are attracted, they close an aperture
which existed between the conducting stopper and the lever
fixed to the armature, and when the armature is detached, the
interruption is made to re-exist. The establishment and rupture of the contact is the only work performed by the transmnitter. There can be given to their springs much less strength
than that of the springs of the bells, and a very feeble current
will suffice to give action to the transmitter.
When the transmitter has established the contact as above