xi
“Before the end of March, 1836, I had invented the
alarum, which is still extant in my first mechanical
telegraph. It was one of ordinary construction, worked by
clockwork mechanism on the removal of a detent. My
invention consisted in placing a voltaic magnet in such
proximity to an armature of soft iron forming the tail
end of a lever detent, that when an electric current
passed round the voltaic magnet, the magnetism which
was for the moment excited in it attracted the tail end of
the lever, and by so doing drew its detent end out of the
clockwork; but on the temporary magnetism ceasing
with the cessation of the current, the attraction of the
tail end of the lever ceased also, and the detent end of it
was then replaced in the clockwork by a reacting spring
or balance weight.”
Dr. Hamel gives the following well-ascertained dates:[1]—
the magnetic needle was deflected by galvanic currents, and in August in the same year
published the discovery at Trent.—(P. 33.)- ↑ The earlier dates of the Telegraphic idea, by frictional electricity, go back to the middle of the last century; and are accurately traced in an article on the Electric Telegraph in the “North British Review” (January, 1855), to a Scotchman in 1755.
