Aerial view of Boon Island Lighthouse Photograph courtesy Library of Congress

As Boon Island is a very flat piece of land, well surrounded by ledges, the tower appears at times to be springing up from the sea from a submerged ledge, especially when low clouds are flying. One of the most isolated stations off the Maine coast, it is also one of the most dangerous.

One story is told of how the keepers were once marooned on the island for several weeks because of storms and rough weather. Their food supplies were low and starvation seemed to be staring them in the face. Just at the point of desperation a boat appeared and they signaled for help. The keeper’s message in a bottle was picked up by the passing schooner which hove to and anchored until the sea went down. Then the crew packed some food in a mackerel barrel and set it afloat. It drifted right into a little cove on the island and then the sea caught it and bounced it well up on the bank, out of the way of the surf. The hunger of the keepers was appeased until they were able to go ashore and get supplies at the village of York.

Boon Island Lighthouse and dwellings Photograph courtesy U.S. Coast Guard

Today the fixed white electric light on Boon Island shows its 120,000 candlepower from a second-order lens for a distance of 18 miles.

The second-order Fresnel Lens from the Boon Island Lighthouse is on display at the Kittery Historical and Naval Museum in Kittery, Maine. The information plaques near the lens read:

The Corduan lenses were ground by a Parisian, Jean-Baptiste Froncois, from “Crown Glass” produced by the Royal Glassworks at St. Gobain near Paris. Crown Glass possesses several advantages over “Flint” Glass, which could also have been used for the lenses. Although Crown Glass has a greenish tint and a lower index of refraction than Flint Glass, Crown Glass is harder, less dense, and less reactive with atmospheric contaminants than lead-bearing Flint Glass. Lighthouse lenses have used Crown Glass almost exclusively since the 1820’s.

When Fresnel first developed his lens design in 1821, he relied upon metallic reflectors to capture and redirect light escaping above and below the lens panels. After his death in 1857, banks of reflecting glass prisms were substituted for the reflectors, because they absorbed less light and required less maintenance. Ultimately, a complete glass lens with central “drum” and upper and lower prisms transmitted 5/6 of the available light, a considerable improvement over the 1/6 emission capabilities of the pre-1821 metallic reflector lights. As an additional improvement (along with greater visibility of the light as seen from the sea), the lamps constructed for these lenses consumed less fuel (oil).

In May of 2000, the lighthouse was leased by the Coast Guard to the American Lighthouse Foundation, which is now responsible for maintaining the tower.

References

1. Historically Famous Lighthouses, U.S. Coast Guard.