Report by Kevin Hofer
The first Point Arena Lighthouse was constructed in 1870. The Lighthouse
is made of brick and mortar. In April of 1906 a devastating earthquake
struck San Francisco. Damage from the trembler occured all along the San
Andreas fault, which runs very close to Point Arena. At the light station
the Keeper's residence and the Lighthouse were damaged so severely that
they were ultimately torn down.
The U.S. Lighthouse Service contracted with a San Francisco based
company to build a new lighthouse here, but the new Lighthouse had to be
able to withstand any future earthquakes.
The new Lighthouse began operation in 1908, nearly 21 months after
the earthquake.
The lighthouse stands 115 feet tall, the lighthouse has a first order
Fresnel lens over six feet in diameter and weighing more than two tons.
This lens literally floats on a bath of mercury contained in a big tub. The
lens contains 666 hand-ground glass parts and a brass frame work, all built
in France.
Before the introduction of electricity the lens was rotated by a clock
work mechanism. The keepers had to crank a large weight up the center
shaft of the tower every four hours to keep the lens turning. Light was
provided by oil lamps which needed constant filling and trimming of their
wicks. Later two 1,000 watt electric lamps and a 1/8th horsepower electric
motor were installed.
In 1776 the fog signals at the station were silenced permanently a
bell-buoy was placed near buy. June of 1977 brought the installation of
an automated aircraft-type beacon on the balcony of the tower, the use of
the Fresnel lens was discontinued forever. The oil lamp was visible 18
miles, the fresnel lens 20 and the rotating beacon 25 miles.