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

AVY'S ELECTRO CHEMI CAL
TELEGRAPH.
CHAPTER XVI.
Nature of the Invention described-The Transmitting Apparatus-The Receiver
-The Instruments combined-The Manipulation-The Signal Alphabet.
NATURE OF THE INVENTION DESCRIBED.
ON the 4th of July, 1838, was sealed a patent to Mr. Edward Davy, of England, for an electric telegraph, which combined the fundamental elements of subsequent chemical systerms. The patent was very extensive, and embraced many
valuable improvements in the art. It was bought by the
Electric Telegraph Company of England, but never used.
The following outline description of the invention will serve
to give an idea of its combinations:
Three wires were to be used, and points of metal wire were to
be caused to press, by means of the motion of magnetic needles,
upon chemically prepared fabric at the distant or receiving
station.
The fabric to be employed was calico or paper, and it was to
be moistened with a solution of hydriodate of potash and muriate of lime.
The motion of a needle to the right caused a mark to be
made on one part of the fabric, and the motion of the same
needle to the left, caused a mark to be made on another part
of the fabric; and the same for each needle attached to the
respective wires. Thus the single or combined marks were
made to express letters or other desired symbols.
THE TRANSMITTING APPARATUS.
Fig. 1 represents a top view of the arrangement of the
wires, mercury cups, and batteries of the transmitting station.
The close parallel lines represent the wires, of which D A B and
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