Telegraph, Facsimile.
A telegraph for transmitting facsimiles of drawing or writing. The
methods employed involve the synchronous rotation of two metallic
cylinders, one at the transmitting end, the other at the receiving end.
On the transmitter the design is drawn with non-conducting ink. A tracer
presses upon the surface of each cylinder and a circuit is completed
through the two contacts. In operation a sheet of chemically prepared
paper is placed over the surface of the receiving cylinder. The two
cylinders are rotated in exact synchronism and the tracers are traversed
longitudinally as the cylinders rotate. Thus a number of makes and
breaks are produced by the transmitting cylinder, and on the receiving
cylinder the chemicals in the paper are decomposed, producing marks on
the paper exactly corresponding to those on the transmitting cylinder.
Synonyms--Autographic Telegraph--Pantelegraphy.
Telegraph, Harmonic Multiplex.
A telegraph utilizing sympathetic vibration for the transmission of
several messages at once over the same line. It is the invention of
Elisha Gray. The transmitting instrument comprises a series of vibrating
reeds or tuning-forks, each one of a different note, kept in vibration
each by its own electro-magnet. Each fork is in its own circuit, and all
unite with the main line so as to send over it a make and break current
containing as many notes superimposed as there are tuning forks. At the
other end of the line there are corresponding tuning forks, each with
its own magnet. Each fork at this end picks up its own note from the
makes and breaks on the main line, by the principle of sympathetic
vibration.
To each pair of operators a pair of forks of identical notes are
assigned. As many messages can be transmitted simultaneously as there
are pairs of forks or reeds.
The movements of a telegraph key in circuit with one of the transmitting
reeds sends signals of the Morse alphabet, which are picked out by the
tuning fork of identical note at the other end of the line.