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

48 IMPROVEMENTS OF SEMAPHORE TELEGRAPH.
nel either its face or edge, and as each panel takes two different positions the whole will give 64 very distinct signals.
This telegraph was introduced into England in 1795, and
has performed much valuable service for the government and
commerce. In searching for facts upon this subject in the
British Museum in London, some years since, I found the above
drawings. They represent their erection close to the earth, as
was the case some half a century ago. High hills were then
chosen, and upon them a rude structure was placed, as seen in
fig. 2.
THE GONON IMPROVEMENT OF THE SEMAPHORE TELEGRAPH.
This improvement is composed of two columns, one of which
is 33 feet, and the other 28 feet high. To each of these two
columns are fitted two moveable arrows. Between these four
arrows the distance is nine feet, which space is filled with six
windows or openings, arranged so as to be opened and closed
at pleasure. There are four dial plates with a crank corresponding to the four arrows, and six keys corresponding to the
six sashes or openings. With this simple mechanism the operator can from his room move the arrows, shut and open the
sashes, and form 40,960 signals, which Mr. Gonon found was
all that would be wanted for a general correspondence. By
adding two fixed lights to each of the sashes, and two moveable lights to each of the arrows, Mr. Gonon said he could,
after some little preparation, operate his machine as a night
telegraph, the signals being exactly the same.
ABRAHAM CHAPPE'S IMPROVEMENT ON THE ORIGINAL SEMAPHORE.
More recently Mr. Abraham Chappe proposed an improvement on the system first erected, which he described in substance, as follows:
Fig. 4. Fig. 5. "In my new system
of numeration and com-—'f ~ — ~ --- - - 7 bination of signals, all
the official signals are given on the horizontal line as represented in fig. 4. During the entire dispatch the indicator alone
Fig. G. moves. Each indicator, in describing its
-^ ~ \ v-^- icircle, stops as here)r.1 V _J, _-, x - i tofore described at the
-_ —, -,- -- v —, - six positions, marked
e- ~- -7 -7 - r- -T 7 in fig. 4, that is, 5,
10, and 1.5 sky; 5,