People who love lighthouses know exactly what a Fresnel lens is: a brilliant invention of the 1820s, it’s a dazzling lighthouse lamp designed to shine much more brightly into the night than anything that previously existed. In the late 1800s, inventor Augustin Fresnel’s ingenious lens was displayed as a marvel at multiple World’s Fairs in front of tens of millions of visitors.
Even if you don’t know what a Fresnel lens is, it’s hard not to be awestruck by its beauty: hundreds of pieces of specially-cut glass faceted in an exact design surround a lighthouse lamp bulb, concentrating the light enough to pierce the darkness for up to 20 miles.
Soon, we’ll all have the chance to gaze up close at one of the best-preserved examples of an original Fresnel lens: the one that lit Thomas Point Shoal Lighthouse from 1899 to the 1980s. This feat of engineering will be the centerpiece of the Annapolis Maritime Museum’s new exhibit space, just a block up from its current Eastport home. It’s a big deal because this glittering piece of history has been living in obscurity for the last 39 years, sitting quietly in a hallway at a Coast Guard administrative building in Baltimore. The lens, worth an estimated $500,000, has been safe behind glass, but kept away from an admiring public that is eager to learn its history.
Thomas Point Shoal Lighthouse Manager John Potvin says he has been wanting to see the Fresnel lens returned to Annapolis since 2004, when the lighthouse changed hands from the Coast Guard to a public-private partnership that includes the City of Annapolis, the Annapolis Maritime Museum, Anne Arundel County, and the Chesapeake chapter of the U.S. Lighthouse Society. “Since 2004 we have lamented the fact that we don’t have the lens,” Potvin admits. And for all those years, he didn’t see much chance of its return. He says, “I’d had conversations for years and was told it will NEVER leave the Coast Guard.”
But all that changed this summer, at a 150th anniversary gala in Annapolis celebrating the 1875 Thomas Point Shoal Lighthouse. Several dignitaries spoke at the event, including Wendy O’Sullivan, superintendent of the National Park Service Chesapeake Gateways Network, in which Thomas Point Light is a key landmark.
Also addressing the crowd was Rear Admiral John C. Vann, Commander of the U.S. Coast Guard East District. Vann noted that Thomas Point was one of his favorite lighthouses, and his father had actually worked as a keeper there.
O’Sullivan teased Vann about the desire to bring Thomas Point’s Fresnel lens back to the current lighthouse owners, even starting a light-hearted chant: Bring back the Fresnel lens! Bring back the Fresnel lens! Most of the audience chuckled, but the conversation wasn’t over.
Potvin tells us that one day after the gala, the call came from Capt. Pat Burkett, commander of the Coast Guard Sector Maryland-National Capital Region. “You’re getting your lens back,” he said.
Burkett liked the idea that the public will get to see and learn about the lens in its new museum exhibit. He told Potvin, “This has been sitting in our lobby for the last 39 years and most people don’t even know what it is. They walk by and pay no attention to it.”
The lens, pronounced “FRAY-nel” and named for its French inventor, Augustin Fresnel, comes in different sizes (known as orders) to indicate focal length. The one from Thomas Point is a fourth-order lens. On the lens, thin, bulls eye-shaped panels refract light both horizontally and vertically, producing a strong beam of light. Its creation was a game changer for mariner safety in the 19th century. The new lens was so superior that by 1860, virtually all U.S. lighthouses used Fresnel lenses.
Thomas Point Shoal Lighthouse, the iconic hexagonal screwpile light seen as a symbol of the Chesapeake, was no exception. Its original lens, a 3.5-order lens installed in 1875, only survived a few years before it was overturned and heavily damaged by the force of ice on the lighthouse. The fourth-order light that replaced it shone to warn ship’s captains of the dangerous shoal nearby for nearly 90 years. The 36-inch, 475-pound lens was finally extinguished and removed from the lantern room in 1986 when the Coast Guard fully automated the lighthouse. It was the last to be automated on the Chesapeake Bay.
With so much historical significance, it’s no wonder the Annapolis Maritime Museum jumped at the chance to display it. Under a formal contract that is currently still in the works, the lens will be on permanent loan to the museum from the Coast Guard, provided it is insured and kept protected. The lens, being so valuable and in such good condition, may not be re-mounted in Thomas Point’s lantern room or be used as an aid to navigation, USCG stipulates.
David Gendell, author of Thomas Point Shoal Lighthouse: A Chesapeake Bay Icon and an Annapolis Maritime Museum Board of Directors member, envisions the Fresnel lens as a symbol of the museum, just as the skipjack Wilma Lee is today.
The Coast Guard’s willingness to share the lens comes at a perfect time for the museum, which just bought the building that houses the Weems & Plath marine instruments company. Gendell tells us, “We’re able to design what happens at Weems & Plath around the Fresnel lens… the floor plan, the flow, all of it will be designed with the lens in mind.”
Gendell sees great educational opportunity in the Fresnel lens exhibit. “It will be brought into the education programs—the STEM curriculum,” he says. “We are already working on oral history about the lighthouse. [The new exhibit] will be a shore-based place that the next generation and the one after that can come and do research.”
The museum’s new space will eventually house most of its entire collection. The historic building currently being used, the former McNasby Oyster Co., is limited on space and is subject to frequent flooding. It will likely become an event space as the museum moves artifacts over to the Weems & Plath building.
Now that an agreement is finally being made to return the Fresnel lens “home”, the act of moving it will be another feat. The maritime museum expects to take possession of the Fresnel lens sometime in spring 2026 and store it until the new space is ready for it. To physically move it from the Coast Guard office to Annapolis, one of only four professional lampists in the nation will come and carefully disassemble the lens piece by piece. If it is so much as jostled, Potvin says, the crystals could be cracked.
The museum estimates the exhibit will be ready for the lens to go on display to the public in late 2026 or 2027.
In the meantime, the Thomas Point Light partnership is working to bring another, less pristine Fresnel lens to display out at the lighthouse itself. Also a fourth-order lens, this one had been sitting in Solomons Island for the last 20 years. It’s unclear which lighthouse it originally belonged to, or how three of its crystals cracked. Gendell and Potvin hope to uncover those mysteries when the lens is disassembled and moved out to the lighthouse in 2026.
You can tour Thomas Point Shoal Lighthouse from late May to mid-October, with tours departing from the Annapolis Maritime Museum. The museum is open year-round, Tuesday through Sunday.
