From the plaque:
This brick lighthouse was
built to incorporate a French first order Fresnel lens.
Although no longer used, the lens is still operable in
the lantern room. Previously the lens had been installed
at Cape Hatteras, North Carolina. It first flashed over
the Pacific in November 1872, and the lighthouse has served
continuously without structural modifications since that
Plaque placed by the State Department of Parks and Recreation in cooperation with the United States Coast Guard, October 2, 1980.