Point Cabrillo Light Station was built in 1908 by the US Lighthouse Service to protect the "Doghole Schooners" that plied the lumber trade between San Francisco and the Redwood Coast. These steam ships and sailing vessels were known for their ability to navigate the small coves, or "dogholes," of Mendocino's rocky shoreline. Its third order Fresnel lens, turned by a clockworks mechanism with a descending weight, concentrated the light of a kerosene lamp through concentric prisms. The light first shone from the tower on June 10, 1909, casting a beam visible 14 miles out to sea. A head lighthouse keeper and two assistants rotated shifts to keep the light burning and fuel the steam-powered air siren. Electricity came to the station in 1935, and a few years later the lighthouse was turned over to the U.S. Coast Guard. In 1972 the Coast Guard retired the fog signal and replaced the Fresnel lens with an automated beacon. Through the combined efforts of the Coastal Conservancy, the North Coast Interpretive Association, the Coast Guard, and many volunteers, the Fresnel lens was reinstated as the operating light in 1999. The Coast Guard continues to maintain the navigational aids with the support of Point Cabrillo staff and volunteers.