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

230 THE ENGLISH ELECTRIC TELEGRAPH.
the hammer is instantly put into rapid vibration, striking alternately the opposite sides of the bell, D; the ringing is kept up
as long as the circuit is closed, but the moment it is broken,
the armature is detached by the spring, f, and the catch is
again pressed into its place on the wheel, d. It is not the voltaic current that rings the bell, but the mainspring in the barrel, or the weight thereto attached. All that the electric current does is to disengage the catch. Any size bell can be rung
by an arrangement of this kind. This is verified by the ringing
of the church bells in Boston, to give the alarm of fire. A central station transmits the electric current through a wire extending to the bells of some dozen churches. An electro magnet at or near each bell, disengages a catch, and the mechanism
is put in motion, and the bell is rung a given time, and the
hammer strikes the bell a given number of times to indicate
the section of the city in which the fire is located.
The bell arrangement herein described is common to all
electric telegraphs. I have described it, because I deemed it
necessary to enable the reader to understand its application to
the needle telegraph.
From the description of the English needle telegraph, the
reader will see that it is not an " inefficient contrivance," but
really an ingenious piece of mechanism, blending principles of
science and art peculiarly simple, and at the same time wonderfully utilitarian. It is a perfect system, and has proved to
be eminently practicable. A month's study and practice renders
an operator capable of managing an instrument. Expertness
follows practice and close application in the perfection of manipulation. An operator can send some 150 letters per minute,
but the rapidity of the signals would be difficult to be under-stood. An expert can receive at the rate of 100 letters per
minute. The usual rate is as fast as the receiver can conveniently write them.
COMBINING AND ARRANGING OF ELECTRIC CIRCUITS.
The arrangement of the wires on the English telegraph lines
are apparently complicated, but in reality their connections are
under the most perfect organization. To enable the reader to
understand something more of the details of the English system, I have selected a few examples to illustrate the respective
points referred to.
The North Kent Line, from London to Rochester, has a
through group of five chief stations on one pair of wires; and
two shorter groups, of six and seven stations respectively, on a
second pair. They are all double-needle instruments, with