As authentic as it gets: Graves Light got an up-close look at the historic 1744 Castle Morro lighthouse in Havana harbor, Cuba, and saw an original Fresnel lens in about as original a state as possible.
On a quick visit to the island last weekend, Graves Light keepers Lynn and Dave talked their way into the lighthouse just as the Morro keeper was reporting for duty.
The light is closed to the public. Lunchpail in hand, Enrizio, the friendly keeper, gave us fellow keepers a tour and took us up to the lantern room.
It was like climbing back in time. What appears to be the original Third Order bivalve Fresnel lens is still in operation.
The lens was made in about 1845 by BBT Paris, the same manufacturer of the old First Order lens at Graves Light, which is now at the Smithsonian Institution.
The keeper fired up the early hand-cranked motor that spins the lens, which still floats smoothly on its mercury bath. Half the windows in the lantern room are cracked or broken out, but the lens produces a brilliant double white flash every 15 seconds. The mechanism is still manually wound every three hours.
The lens was modified by “the French” in the 1950s with the addition of small reflecting panels to bend some of the beam 45 degrees upward so that aircraft could navigate by its light. Other than those panels and an electric lamp that uses a 70 watt halogen bulb, the entire apparatus appears completely original.
Each evening, the keeper withdraws the curtains and engages the mechanism to spin the lens. By day, the curtains are drawn to prevent the sun from entering the lens and starting a fire inside.