Joseph Henry was born on December 17, 1797, in Albany, New York. Henry's family was poor; his father could not afford to send his son to school, so the boy received a very limited education.

According to legend, in 1813 Henry chased his pet rabbit under a church. While crawling around, Henry noticed some floorboards were missing and crawled up into the church. There he came across a shelf of books and began browsing. One book, Lectures on Experimental Philosophy, got him hooked on science. He took a job teaching at a country school to earn money and enrolled at the Albany Academy. He intended to study medicine, but he had a job offer as a surveyor, and this aimed him toward engineering. In 1826 he was still at the Albany Academy, but as a teacher in the subjects of science and mathematics.

Meanwhile, in 1820, Danish Physicist Hans Christian Oersted had made...