Scarcely known today, Elihu Thomson was arguably the most important early contributor to the development of electricity as a power and light source. An outstanding scientist as well as a brilliant engineer, Thomson applied his insights in theoretical science to practical devices in a way that few others have.

Thomson was born in Manchester, England, on March 29, 1853, and his family moved to Philadelphia five years later. The son of an engineer and machinist, Thomson was tinkering and inventing before he had even reached his teens. Keenly interested in electricity, Thomson constructed a crude electrostatic device from a wine bottle at the age of eleven, as well as experimented with telegraphy, electromagnets, and other electrical devices.

Shortly after graduating from Central High School, Thomson became a faculty member there, and began working with another teacher, Edwin J. Houston. Appointed professor of chemistry and mechanics in 1876, Thomson spent his time...