Joseph Henry and the Motor in the Academy

In eighteen thirty-one, a professor at Albany Academy built one of the first practical electric motors. His name was Joseph Henry, he was in his early thirties, and he was working with materials that were, by the standards of later laboratories, almost laughably simple, wire, battery cells, and iron bars. What he coaxed from them changed the world.

Henry was investigating electromagnetism at a time when the field was barely understood. He developed techniques for winding insulated wire around iron cores to dramatically increase the magnetic force a coil could produce, a method he kept largely to himself. He built a rocking beam driven by two electromagnets and two batteries, switching the current back and forth automatically: a motor.

It was small, it was crude, and it worked. Henry also independently discovered electromagnetic self-induction, the principle that a changing magnetic field in a coil induces a voltage in that same coil, around the same time Michael Faraday was working toward the same conclusion in England. Faraday published first; history gave him primary credit.

The unit of electrical inductance is now called the henry, a consolation that acknowledges what he found without diminishing what Faraday proved. Albany is not a city that advertises this particular chapter of its history with much urgency. There is no great monument to Joseph Henry near the academy.

He went on to become the first secretary of the Smithsonian Institution. His discoveries live in every electric motor, every generator, every transformer that has ever been built.