Graves Light gets another first-order Fresnel lens

gl-john-nelson-randy-clark-do-final-fitBig news, everybody. Graves Light received a little taste of a genuine first-order Fresnel lens, similar to the original 1905 lens that sent out a 350,000-candlepower beam across the harbor.

The Coast Guard is still in charge of the navigational aids at Graves, so we couldn’t make the beacon shine like it did before the original giant Fresnel lens was removed in 1975. Since 1905, Graves had been the most powerful lighthouse in New England. Not so any more.

So we did the next-best thing by reconstructing part of the lens with pieces from lighthouses around the world. We assembled them as part of the interior decor in a way that won’t interfere with the modern, solar-powered lamp.

What’s a first-order Fresnel lens?

John and Randy assemble the flash panels to adorn the kitchen on the watch deck.

For a lighthouse, a Fresnel lens is a beehive-shaped compound lens made up of rings of glass prisms that cast parallel beams of light.

It is named after its inventor, French physicist Augustin Jean Fresnel (1788-1827), who had a special understanding of the physics of light.

Lighthouse lenses are divided according to size and light focal length, a category called “order.” Formally there are eight orders of Fresnel lenses, with the first-order being the largest. (There is also a 3-1/2-order lens. Two larger lenses were ultimately developed.)

A first-order lens casts a beam that can be seen more than 20 miles away. Only the curvature of the Earth prevents it from shining further on a clear night.

Fresnel lenses are made of heavy glass prisms housed in large brass or bronze frames, assembled as panels and arranged in a circle. The entire assembly of an operating Fresnel lens rotated on mechanical carriage or a pool of mercury, and in some parts of the world, still does. That liquid heavy metal ensured steady, constant, friction-free rotation, regardless of the weather, on a corrosion-free surface. The Coast Guard recovered 400 pounds of mercury from Graves when it removed the lens. Our new lens is stationary and won’t be used as an aid to navigation, so there’s no rotation mechanism or mercury.

Where did the new Graves first-order Fresnel lens come from?

We assembled the new Graves lens from several antique first-order lenses from decommissioned or modernized lighthouses outside the United States. Nearly all first-order Fresnel lenses have been destroyed, or are owned by governments as legacy artifacts. No complete first-order Fresnel lens exists in private hands, anywhere in the world.

Working through Chance Brothers Lighthouse Engineers of Melbourne, Australia, we bought pieces from English lenses built between 1880 and 1920.

Wyatt designed the bronze frame by computer, and built a full-scale wooden mockup.

Wyatt designed the bronze frame by computer, and built a full-scale wooden mockup. Then he assembled the frame on the mainland to make sure everything fit.

Reconstructing a lens

A first-order Fresnel lens would generally consist of glass prisms assembled in about 45 panels.

The panels are stacked three high and arranged in a circle. The lower and upper panels are called catadioptric panels and bend the light by reflection like a mirror. The center sections, or flash panels, are dioptric prisms which concentrate the light like a magnifying glass.

We acquired glass prisms to fill 15 panels. For considerations of living space and climate control – and for the practical matter of finding enough prisms – we did not attempt to rebuild an entire first-order lens nor could we. These panels are so scarce, it appears there may be no more to be found!

The objective was to illustrate the wonder of a First Order lens without taking over our kitchen.

No shop drawings for assembling a lens like this exist. It’s been said the factories that made them in England and France were destroyed during World War II. Our own Wyatt designed a custom skeleton frame using SolidWorks software, and uploaded the specifications to a water jet cutter, producing a rigid structure out of 1/2-inch bronze plate.

The assembly in our shop allowed us to correct mistakes, make sure the glass prisms fit properly, and refine each frame to ensure a good fit-out on station.

We packed each completed panel in wooden crates, brought them to Graves Light aboard Miss Cuddy, and winched them halfway up the lighthouse to the entrance, and hand carried them up the tower for installation.

After assembly, we found that the lens focused sunlight inward and melted our first aid kit. We knew from our neighbor Sally Snowman, keeper of Boston Light, and our visit to the Castle Morro lighthouse in Havana, that the old Fresnel lens lighthouses had interior curtains to block the sun by day. Both the Boston and Havana lighthouses still have operational Fresnel lenses.

So we went to Zimman’s for a bolt of the proper cloth. Our own Keeper Lynn is creating a custom curtain to prevent the sunlight from starting a fire, without the curtain obstructing the navigational lamp.

Vital statistics

  • Manufacturer: Chance Brothers of England
  • Grade: First Order Lens
  • Origin: From several lighthouses worldwide, circa 1880-1920
  • Weight of a complete sense: 3 tons
  • Weight of our lens apparatus: 1 ton
  • Height: 9 feet
  • Diameter: 6.5 feet
  • Light strength: Approximately 350,000 candlepower with kerosene burner

Where’s the original?

The original Graves Light lens, made in Paris by Barbier, Bernard and Turenne, is in the possession of the Smithsonian Institution in Washington, D.C. It isn’t on display, but is probably crated up in a warehouse. The Smithsonian loans out many of its pieces for public display, but federal law forbids the original Graves lens from being exposed to weather, so we couldn’t move it back to the lighthouse even if the Smithsonian would let us (which it won’t.)

The Coast Guard loans out Fresnel lenses under strict conditions, but requires that they be kept in climate-controlled environments, and, for preservation purposes, forbids them to be kept in lantern rooms.

See Theresa Levitt’s biography of optical genius Augustin Fresnel and his remarkable impact on lighthouses and navigation, A Short Bright Flash: Augustin Fresnel and the Birth of the Modern Lighthouse (Norton, 2013).

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All toasty with our potbelly stove, 4 miles out to sea

Dave sweeps up by the first fire in Graves Light's new potbelly stove.

Dave sweeps up by the first fire in Graves Light’s new potbelly stove.

Mary lights the potbelly stove for the first time.

Mary lights the potbelly stove for the first time.

November 2016 began with a warm wood fire from our new potbelly stove.

This is the first time Graves Light has been heated in about 40 years.

It’s pretty nice to sit up here as the weather cools down and we don’t have to freeze On Station.

Thanks to the creative people at Nelson Metal Fabrication in South Portland, Maine, and our trusty volunteers, we now have a fully functional potbelly stove to keep us warm.

We found an antique smokestack salvaged from an old yacht.

The folks at Nelson turned the smokestack into a 12 foot-tall chimney, hauled it down from Maine, and installed it at Graves Light.

Here’s how they did it

They connected the stove on the third deck with the original chimney shaft in the wall, and then ran the newly fabricated section of pipe and yacht smokestack through the original 1905 chimney stack channel, out the granite watch deck, and up and out the lamp deck.

The gallery below tells the story in pictures: from Nelsons’ shop in Maine, to the fitting together of the new chimney with the old smokestack, to Jim and John installing the stack in the old chimney assembly at the lighthouse.

Then a photo shows how the old yacht smokestack sits in place, out of the lamp deck, like the 1905 original.

And finally  –  the glorious potbelly stove all lit up, filling the lighthouse with a welcoming warm glow from its iron hearth.  Plus cleanup time.

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At the top: CCI is back to seal the roof from the weather

Mike from CCI Construction waves as he starts work sealing the roof of Graves Light.

Mike from CCI Construction waves as he starts work sealing the roof of Graves Light.

Back for their third season: Mike Sylvester and his team from CCI Construction are back at Graves Light again to seal it from the seas and weather.

You might remember Mike from two years ago, as he was suspended 80 feet down over the rocks to repair the outside stonework.

Now he’s 113 feet up to seal the roof.

One of their tasks is to caulk and paint the conical roof above the lantern room. Here’s a shot of Mike, roped in, of course, waving as he prepares to work. The lantern room has been a source of leaks, but the guys at CCI are sealing it all up for us.

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Original drawings aid in door restoration

These custom-built stainless steel replacement hinges should last another hundred years.

These custom-built stainless steel replacement hinges should last another hundred years.

The leaky bronze doors on the Watch Deck needed new hinges to create a perfect seal against the weather.

We just couldn’t buy them in a store, or even find antique originals.

So we went back to the drawing board and used the original architectural drawings of Graves Light from 1903.

Those drawings included sketches and dimensions of the original hinges.

John Nelson of Nelson Metal Fabrication has fixed the leaky doors. John did a lot of great work for us already, and now it was time for more.

Using the original designs as a guide, John machined new stainless hinges to perfectly match the damaged old ones. Now the doors shut tight! The hinges should last until the 22nd century, at least.

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Next project: Installing an electrical system 4 miles out to sea

Art Graves drills into the cast iron ceiling to prepare installation of restored ship's lanterns.

Art Graves drills into the cast iron ceiling to prepare installation of restored ship’s lanterns.

Power up! The next big project is running the wires for lights and outlets.

Graves Light has no electric power of its own, except for the solar-powered lamp to guide ships to Boston.

Since it’s an unforgiving environment atop a stone ledge four miles out to sea, every connector, fixture and device must be marine-rated.

Here we have Art Graves (yes – that’s his real name) drilling into the cast iron ceiling to mount the antique ship’s lamps we restored over the winter.

Refurbished bronze ship lanterns will provide electric light to Graves.

Refurbished bronze ship lanterns will provide electric light to Graves.

Soon we’ll install bronze lamps salvaged from old ships as interior lighting at Graves.

We cleaned up and reserved the lamps over the winter, so they’re ready to go.

Tough drilling overhead!

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New USCG ladder now on Graves Light wharf

Installing a new USCG ladder on the Graves Light wharf.

Installing a new USCG ladder on the Graves Light wharf.

A great weather weekend on April 9-10 found us “on station” with friends. Lots of springtime projects on our list, and one of the most important is installing the ladder at the end of the wharf.

Here’s Cap’n Pat and Chris readying the USCG ladder (which we’ve half-installed) after they secured our trusty aluminum ladder and hoist. Sure makes loading materials and people easier!

Plenty of seals frolicking in the cove today, too.

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Custom building a lighthouse kitchen stove

With his high school engineering education and his own imagination, Wyatt designs the stove.

With his high school engineering education and his own imagination, Wyatt designs the stove for a small space with curved walls.

Without any flat interior walls, a lighthouse needs custom-made everything. Since kitchen space is the most precious, and the sea air corrosive of steel, conventional appliances just won’t work.

Wyatt's bronze stovetop, after it came back from the metal shop.

Wyatt’s bronze stovetop, fresh from the metal shop.

Luckily, Wyatt is studying engineering in high school. After drawing out the exact curve of the interior wall of the watch room, Wyatt whipped up a curved stovetop design on his computer.

We sent Wyatt’s design to a metal shop, which crafted a stovetop out of 1/2-inch thick bronze, using a water jet cutter.

The rest is up to us. We’re modifying propane barbecue burners to fit under the top and will design a curved faceplate for the knobs.

Can you smell a delicious chowder simmering this summer?

The stovetop design, from computer to metal shop.

The stovetop design: Wyatt measured the curve from the lighthouse radius, for fabrication from a sheet of half-inch-thick bronze.

 

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Bronze rails in the lantern room

John builds the bronze lantern railing so that we can have an open area and still keep the beacon secure as a US Coast Guard aid to navigation.

John builds the bronze lantern railing so that we can have an open area and still keep the beacon secure as a US Coast Guard aid to navigation.

Remember those bronze castings we made over the winter? John and John from Nelson Metal Fabrication machined them to perfection and fitted pickets and rails made up in their Portland, Maine shop.

John installs the bronze lantern railing. The solar-powered beacon is visible at top right.

John installs the bronze lantern railing. The solar-powered beacon is visible at top right.

Then they brought them out to Graves and hoisted them up the ladder and into the lantern room.

Three days later, the results are amazing.

Graves Light remains an active aid to navigation. We have to make sure that while we make as much use as we can of the lantern room, the topmost level of the tower, we have to keep the solar-powered lantern safe and free of obstructions. We also have to make sure it remains accessible to the Coast Guard for their maintenance visits.

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New brass castings set to restore mahogany handrail

John Nelson at work on the new brass fittings we custom-cast to restore the handrail system.

John Nelson at work on the new brass fittings we custom-cast to restore the handrail system.

Here’s a sneak peek from John Nelson’s metal shop in Portland, Maine.

John is coming down to install a beautiful reproduction of the original railing system, complete with a mahogany handrail.

Over the winter, we designed and cast some of the brass parts for this railing. It will be exciting to see the finished results. Of course we’ll keep everyone posted.

Follow John Nelson on Instagram @nelsonmetalfab, and like his shop, Nelson Metal Fabrication, on Facebook.

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Discovered: Original Fresnel Lens rotation mechanism

Polishing a century of grime from one of the brackets of the original First Order Fresnel lens rotation mechanism.

Polishing a century of grime from one of the brackets of the original First Order Fresnel lens rotation mechanism.

Ever wonder how the giant First Order Fresnel lens rotated to produce that smooth, sweeping beam lf light?

The good guys at the US Coast Guard revealed the secret by sending us the old engineering drawings of parts of the original mechanism, which are still bolted to the 5th level ceiling.

Since that ceiling is being restored, we figured we’d take the mechanism down and clean it up, which we did this week at home.

Here’s how it worked: Every two hours the Keepers wound a 300-lb weight up a 50-foot tube using a hand crank. The weight was connected by a series of pulleys (pictured) and connected to a big clockwork device, which regulated the speed and drove a gear that spun the two-ton lens.

The system was converted to an electric motor long ago, but happily the Coast Guard left all the old stuff in place, which made it possible for us to tell the story.

 

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