Lighthouse tech detailed: Area expert gives presentation

A crowd gathers to listen to Kurt Fosburg, a professional lampist and vice president of the Marquette Maritime Museum Board of Directors, give a presentation on lighthouse optics during the Marquette Maritime Museum’s Maritime History on Tap at the Ore Dock Brewing Co. (Journal photos by Kat Torreano)


Journal Staff Writer

MARQUETTE — Lighthouse beacons have been used practically and metaphorically as tools for navigating safely through dark and difficult waters for centuries.

But how often is the technology that makes these structures function considered?

Professional lampist Kurt Fosburg gave a presentation on lighthouse optics at Ore Dock Brewing Company in Marquette Tuesday evening as part of the Marquette Maritime Museum’s History on Tap series.

Fosburg, who is also vice president of the Marquette Maritime Museum’s board of directors, discussed the history and function of Fresnel lighthouse lenses and equipment, as well as his experiences working on the lens pedestal he built for the major motion picture, “The Lighthouse,” starring Willem Dafoe and Robert Pattinson.

The critically acclaimed film won best in show at the Cannes Film Festival last year and put a spotlight on the Fresnel lens for a modern audience.

“Well, first of all, everybody loves lighthouses,” Fosburg said. “But this is not a talk about lighthouses. And lighthouses are really cool. They’re beautiful. They’re very photogenic. We all enjoy them. But there was only one reason for that structure. That structure was only there for that little glass room on the top called the lantern room.”

In its purest form, there are only three parts to a lighthouse, the tower, the lens and the lamp, Fosburg said. While lighthouse keepers worked around the clock to maintain the tower, keep the lamp lit and clean the glass, it was the job of the lampist to install and repair the lens.

“A lampist is the term — it’s an old-world term — for the individual who used to travel to the lighthouses to work on the Fresnel lenses,” Fosburg said.

While his profession was a fairly common trade in the 1800s, Fosburg is currently one of only five other lampists in the United States. He specializes in restoring, moving, cleaning and interpreting original classical Fresnel lighthouse lenses and their components.

The Fresnel lens was developed by Frenchman Augustine Fresnel in the early 1800s. The lens is made up of a series of concentric rings that resemble ripples on the water’s surface. Each ring is placed at a specific angle to focus scattered rays of light emitted from a lamp source into one concentrated narrow beam. The tighter the beam, the longer the distance the light can be seen.

“They are actually quite simple — they focus the light,” Fosburg said.

Lenses come in six sizes called “orders.” The fifth-order Fresnel lens was the most commonly used Fresnel on the Great Lakes and was used as a breakwater light for boats coming into a harbor.

The largest lens used on the Great Lakes was a second-order lens. An example of this can be found on display at the Marquette Maritime Museum, as it hosts a 6-foot by 8-foot second-order lens from the Stannard Rock Lighthouse.

“These lenses are extremely fragile,” Fosburg said. “They’re not durable; they have to be maintained. They have to be washed; they have to be cleaned and refueled.”

In 1895, a 14-inch glass and copper valve called the sun valve was invented and made the lighthouse keeper’s job obsolete by automating the lamp fueling process.

“This is a government agency, you have to pay a keeper, you have to pay his family, you have to pay for food, housing and all that kind of stuff,” Fosburg said. “If you can automate something with a little tiny glass jar, they’re going to do it. And that’s what they did. So this actually this little tiny thing was what spelled the end of all my house service as we know it.”

With the advent of electricity and other advancements in technology, Fresnel lenses were replaced by more durable materials.

Fosburg said that these fragile, delicate objects were “in a world that was moving a lot quicker than they were.”

Thus, the outdated glass beacons fell prey to sun damage, disrepair, vandalism and the effects of gravity.

With the advent of GPS technology, the lighthouse may no longer be necessary.

However, Fosburg believes that they still serve a purpose by bringing solace to mariners.

“So a lighthouse is comforting, just knowing that they’re going to leave the light for you,” he said. “You’re coming back into port in the storm is approaching: You to want to get in the soon as you can, you got to head for sure and wait out for a better day.”

The Marquette Maritime Museum’s winter lecture series, Maritime History on Tap, is held at 7 p.m. the first Tuesday of the month November through April at the Ore Dock Brewing Co. along Spring Street in Marquette. There is a $5 suggested donation at the door.

For more information on the upcoming events, visit mqtmaritimemuseum.com.

Corey Kelly can be reached at 906-228-2500, ext. 243. Her email address is ckelly@miningjournal.net.


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