Page:Hamel Telegraph history England 1859.pdf/95



“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: —