He did not succeed in producing direct rotary motion.

His bar oscillated like the walking beam of a steamboat.
Henry was appointed in 1839.

Professor of Natural Philosophy in the College of New Jersey, better known today as Princeton University.

There he repeated his old experiments on a larger scale, confirmed Steinheil's experiment of using the earth as return conductor, showed how a feeble current would be strengthened, and how a small magnet could be used as a circuit maker and breaker.

Here were the principles of the telegraph relay and the dynamo.
Why, then, if the work of Henry was so important, is his name almost forgotten, except by men of science, and not given to any one of the practical applications of electricity?
The answer is plain.