State-of-the-art lens at SLO County lighthouse helped keep ships on course for nearly a century
The Fresnel lens was considered breakthrough technology in its era.
French physicist Augustin Fresnel began life as a slow learner. He could barely read by age 8.
However, his dogged ability to solve problems led to the creation of a state-of-the-art lens that captured and transmitted 83% of the light from a lamp.
A flame with a reflector only captured 13% of a lamp’s light and an open flame only transmitted 3% to a viewer.
The combination of prisms and bullseye magnifiers was the most important breakthrough in lighthouse lenses in 2,000 years, according to the Dunkirk Lighthouse website.
Fresnel worked out the formulas to refract light, bending it from scattershot into a concentrated beam.
Working with the best glass artisans of the day a first-order Fresnel lens — the strongest of them all — can weigh several tons with thousands of prisms and dozens of bullseyes.
After the United States created a Lighthouse Board of scientists and mariners, the Fresnel lens became the preferred tool of lighthouses, helping to keep ships on course and away from dangerous stretches of coastline.
As late as 1973, the Point San Luis Lighthouse near Avila Beach was still using a French-made fourth-order Fresnel lens, but the 19th-century lens had to be cleaned on a daily basis.
Automation was coming and the once manned lighthouse would become a museum.
Guided tours of the lighthouse on the San Luis Obispo County coast are available by reservation. For more details, go to pointsanluislighthouse.org.
Mark Gladstone wrote this story near the end of the era for the Fresnel lens, published on Nov. 10, 1973.
On foggy nights you could hear the horn in town
Point San Luis Light doesn’t look like a lighthouse. It doesn’t stand erect like a striped barberpole, like some other lighthouses along the Pacific coast. Wood, not stone, forms its squat superstructure.
That wood was sculpted into a simple prairie-Victorian house with a graceful windowed tower to serve as a lighthouse. The house itself is barely visible on the private road leading to Point San Luis. It is obscured by a grove of trees.
For more than three-quarters of a century the lighthouse and nearby foghorn have alerted passing ships to the proximity of the rough rocky coast.
When the light was first planned in the late 1880s, the shipping industry was booming in Port Harford, now Port San Luis. Large ships made it a regular stop. Even then, Avila was a tourist stop for those seeking refuge from the heat. For a while a whaling station thrived on Whaler Island, south of the light.
This was the West. Men were beginning to realize it was the last American frontier.
With that realization and increased commerce, came the need for a lighthouse.
The federal government appropriated $50,000 and acquired the 30-acre site. U.S. Coast Guard records indicate that the original contractor failed to complete the lighthouse as scheduled in December 1889, but work finished in the spring of 1890.
The Point San Luis Lighthouse joined dozens of other beacons at the edge of the continent aiding the nation’s growing shipping trade.
The lightkeeper’s house is now boarded up. Dark, empty and chilly. The adjacent light is still in use.
And up in its turret-like top, two young Coast Guardsmen clean the prisms of the old light. Portions of the light were shipped from France. On its edge is written “SAUTTER LeMONNIER et … Paris 1878.”
The two young men are Gregory G. Scott, 23, officer-in-charge-of the light station and his assistant, Michael E. Gardner, 22.
Both men live with their wives in houses constructed in 1960. They have been stationed at the light since early this year.
“Our major job is to make sure the equipment is working,” said Scott, a native of Nebraska.
Without doubt, Scott and Gardner keep the equipment running.
”Brhhhh.” The stentorian fog horn belches its throaty roar five miles out sea.
On foggy days and nights the directional horn blows in two three-second rounds and then there is silence for 50 seconds.
“You get used to it,” said Scott.
Longtime residents say that the original horn’s roar echoed across hilltops to San Luis Obispo on foggy nights.
Scott says the fog will rest against Point San Luis for three or four days at a stretch.
“It’s so depressing. You can’t even see a fence a few feet away,” he says.
In case of prowlers, Scott and his wife Mary have their own foghorn. Otis, their German shorthair dog, barks when strangers appear at the light.
Eventually the sounds of people may not be heard at the lighthouse.
Automation has been discussed for at least six years, and finally will become a reality “some time after July 1974,” according to Coast Guard Lt. Armand Chapeau in Monterey.
Until then Coastguardsmen will be stationed at the light.
They must maintain equipment which sends a radio beam to sea for ships to get their bearings, three simplex clocks set to Greenwich mean time and an instrument that automatically detects the approach of fog.
The light itself is powered by a 1,000 watt electric globe which has a beam of three-quarters of a million candlepower. On a clear night, its keepers say, it can be seen for 17 miles.
Many of the original buildings, like an old barn, have been torn down. Other artifacts have been removed to the safety of federal archives in Washington D.C.
For instance, the register of visitors was sent to the archive eight or nine months ago, according to Chapeau.
The register goes back to March, 23, 1893. Among the names on the first page is that of Gertrude Jack, member of one of the county’s best known early day families.
Port San Luis harbor manager Ken Jenkins, hopes the register will be returned to the lighthouse. He wants the lighthouse to be turned into a public museum
Coast Guard officers said they realized the community interest in the historical nature of the site but have no plans at present of offering the lighthouse to the Port San Luis Harbor District.
In the quietude of the fog, the house is chilled by a wind — the same wind which the trading ships caught sailing in and out of Port Harford.
The fog has always been a potential enemy. The light has been a gentle friend and companion. The lighthouse was once a symbol of the expanding American culture on the county’s coast. One day soon it may be the receptacle for the history of those days.
