Pigeon Point Lighthouse's tall, double-walled tower supports a huge four-ton lens. The first-order, or largest, Fresnel lens has 1,008 glass elements mounted in a brass framework. This lens system was perfected by Augustin Fresnel in 1822. Manufactured in France, the lens focuses light from a flame or bulb into 24 separate beams that radiate outward up to 24 miles on a clear night. As the powerful clockwork mechanism slowly rotates the lens, mariners see a white flash every 10 seconds. The lighthouse's lens was first lit on November 15, 1872. The 24 bulls-eye lenses and 984 prisms create 24 beams of light, and the spiral staircase includes 136 steps forged in San Francisco. The tower is 115 feet tall on a 50 foot bluff and was built with 500,000 locally made bricks. The keepers, known as "wickies," maintained the flame and wound the clockwork mechanism of the lens, with 3 to 4 keepers working 4 hour duty shifts. The lantern illuminant changed over time from lard oil in the 1870s through 1880s, to kerosene in the 1880s through 1920s, to electricity in the 1920s through 1970s, and since the 1970s it has been automated with an exterior beacon.
