Whale oil
Construction began in 1787 at the directive of George Washington, and was completed on January 10, 1791, using a fund of $1,500, established by him. Whale oil lamps were originally used for illumination. In 1855, following formation of the Lighthouse Board, a fourth-order Fresnel lens was installed; that lens was replaced by a second-order Fresnel lens, which was replaced later by an aerobeacon in 1958. That lens was updated with a DCB-224 aerobeacon in 1991.