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

IMPROVEMENTS PATENTED IN 1838. 207
bar to key, 1; then to wire, 1; then to electrometer,; and
through it, deflecting the lower half of the needle to the right;
thence it proceeds along the extended wire, 1, to the Paddington station; entering the dial to the electrometer, 1, deflecting the lower half of the needle to the right; then along wire,
1, to the key, 1; then to button 9; then to the cross-bar, N,
beneath; and then to the negative pole of the battery, o. It
will be observed, that the needles of both stations, thus deflected, point to the same letter v.
If a numeral is be signaled, it is obvious, that but one electrometer is needed. We will, therefore, suppose that the needle,
1, is vertical.
Let the buttons, 7 and 16, be pressed down, at the Paddington station. The current then leaves the positive pole of the
battery, o, to the cross-bar, p; then to the key, 4; then along
wire, 4, to electrometer, 4, deflecting the lower half of the
needle to the left; thence to the Slough station to electrometer, 4, deflecting the lower half of the needle to the left;
then to wire, 4; then to key, 4; then to the cross-bar, I, and
I., and along it to key, 6; then to wire, 6, and along the extended wire to the Paddington station, to key, 6; then to the
cross-bar beneath the button, 7; then to the negative pole of
the battery, o. The needles, 4 and 4, of both stations, are
simultaneously deflected, so as to point to the figure, 4, on the
margin of the dial.
In this manner the circuits required for each letter and
numeral may be traced out. Now, suppose the message to be
sent from the Paddington station to the Slough station, is this,
6; WE HAVE MET THE ENEMY AND THEY ARE OURS." The operator
at Paddington presses down the buttons, 11 and 18, for signalizing upon the dial of the Slough station, the letter w. The
operator there, and who is supposed to be constantly on the
watch, observes the two needles pointing at w. FHe writes it
down, or calls it out aloud, to another, who records it, taking,
according to a calculation given in a recent account, two seconds
at least, for each signal. Then the buttons, 10 and 13, are
pressed down, and the needles are observed to point at E; and
so for the remaining letters of the sentence, u excepted, which
has no letter on the dial.
IMPROVEMENTS PATENTED IN 1838.
The second English patent was sealed 18th of April, 1838,
for an improvement, with the power of communicating from
intermediate points in either direction; but when not working,
the alarum belonging to it could be sounded from either termi