This discovery was made in 1831, the year before the idea of a working electric telegraph flashed on the mind of Morse.

There was no occasion for the controversy which took place later as to who invented the telegraph.

That was Morse's achievement, but the discovery of the great fact, which startled Morse into activity, was Henry's achievement.
In Henry's own words: "This was the first discovery of the fact that a galvanic current could be transmitted to a great distance with so little a diminution of force as to produce mechanical effects, and of the means by which the transmission could be accomplished.

I saw that the electric telegraph was now practicable." He says further, however: "I had not in mind any particular form of telegraph, but referred only to the general fact that it was now demonstrated that a galvanic current could be transmitted to great distances, with sufficient power to produce mechanical effects adequate to the desired object."* * Deposition of Joseph Henry, September 7, 1849, printed in Morse, "The Electra-Magnetic Telegraph", p.

91.
Henry next turned to the possibility of a magnetic engine for the production of power and succeeded in making a reciprocating-bar motor, on which he installed the first automatic pole changer, or commutator, ever used with an electric battery.