One needle could, by the use of this wire, be deflected by itself, either to the right, or to the left, and thus, of course, each would furnish two signals in addition to those formed by its simultaneous deflection by any other. The instruments at the two stations were always rendered reciprocating; that is, at each end of the line were placed at each instrument a set of finger keys and a Voltaic battery, so that either station could transmit, or receive a signal by an ingenious arrangement. The keys on being released after depression, were made to resume by themselves the position necessary to enable that which had been the signalling station to become the recipient; by this means messages and answers or words and their acknowledgment could follow one another without the necessity for any intervening adjustment of the instruments.
The bell or alarum which was to be rung, when the attention of the clerk at the distant end was required, was either direct or indirect in its action.
In the first case, the attraction exercised by a horseshoe-shaped piece of soft iron, rendered temporarily magnetic by the galvanic current, was made to draw an armature likewise of soft iron towards it, and by this action impel a small hammer against a bell.
In the second form of alarum the movement of the armature merely released a detent or catch from a train of clock work driven by a spring or weight. This clock work by the intervention of a scape wheel and pallets rang the bell as in a common alarum.
In April, 1838, Mr. Cooke obtained a patent for some further improvements in this apparatus.
The electric telegraph invented by Prof. Morse, of the United States, has led to a large amount of controversy, a claim having been put in for him as the first actual invention of a practical electric telegraph in 1832, while on board the packetship “Sully.”
The Abbe Moigne states that a Mr. Jackson wrote to the Academie Française, affirming that he had in 1832 communicated the plan to Mr. Morse while returning together from Europe to America on board the “Sully.”
Even admitting, however, the claim of either party, it would only show that they did not think sufficiently well of their scheme to enter upon it until nearly three months after the first English patent for an electric telegraph had been sealed and the practicability of such an apparatus had been demonstrated in England.
The first really official letter on the subject from Prof. Morse is dated September 27, 1837.
Cooke and Wheatstone’s first patent for an electric telegraph was sealed three months before this, namely, on June 12, 1837.