The Joseph Henry Papers Project - The Smithsonian Institution
The other leading candidate was Joseph Henry (1797-1878). Henry's candidacy was based on the proposition that the Secretary of the Smithsonian should be the greatest living American scientist, someone with an international reputation.

Few would dispute that Henry fit that description. In 1846, he was professor of natural philosophy (physics) at the College of New Jersey (now known as Princeton University). He had published scientific articles on a wide variety of subjects, including electromagnetism, optics, acoustics, astrophysics, molecular forces, and terrestrial magnetism, but his reputation was built primarily on his work in basic and applied electromagnetism.

Among his discoveries in electromagnetism were mutual induction, self-induction, the electromagnetic relay--enabling him to devise the first electromagnetic telegraph that could be used over long distances--and the concept of the electric transformer. He also invented the first electric motor.

Henry was often referred to as the scientific successor to Benjamin Franklin. . . . more at The Smithsonian Institution

Key Elements of Electromagnetic Telegraphy- Harvard Univ.
" ... It is certain that Joseph Henry was important to the history of the telegraph in two ways. First, he was responsible for major discoveries in electromagnetism, most significantly the means of constructing electromagnets that were powerful enough to transform electrical energy into useful mechanical work at a distance. Much of Morse's telegraph did indeed rest upon Henry's discovery of the principles underlying the operation of such electromagnets.

"Secondly, Henry became an unwilling participant in the protracted litigation over the scope and validity of Morse's patents. ..."

"... Joseph Henry began his research into electromagnetism in 1827, while he was an instructor at the Albany Academy in New York. By 1830, he achieved two major breakthroughs .... His first crucial innovation, which he demonstrated in June 1828, was to combine Schweigger's multiplier with Sturgeon's electromagnet to obtain an extremely powerful magnet. While Sturgeon loosely wrapped a few feet of uninsulated wire around a horseshoe magnet, Henry tightly wound his horseshoe with several layers of insulated wire. In March 1829 he demonstrated an electromagnet with 400 turns, or about 35 feet, of insulated wire. This magnet, Henry remarked later, "possessed magnetic power superior to that of any before known."

"... Henry did set out to demonstrate the practicability of an electromagnetic telegraph immediately after his paper appeared. His prototype consisted of a small battery and an "intensity" magnet connected through a mile of copper bell-wire strung throughout a lecture hall. In between the poles of this horseshoe electromagnet he placed a permanent magnet. When the electromagnet was energized, the permanent magnet was repelled from one pole and attracted to the other; upon reversing battery polarity, the permanent magnet returned to its original position. ... Henry caused the permanent magnet to tap a small office bell. He consistently demonstrated this arrangement to his classes at Albany during 1831 and 1832." . . . more at Smithsonian Institution