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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Engineer who removed original Fresnel lens returns to Graves

Engineer Ron Fiore explains to Dave how he devised the system to remove the original Fresnel Lens from Graves.

On the deck of Graves Light for the first time since 1975, engineer Ron Fiore explains to Dave how he devised the system to remove the original Fresnel Lens from Graves.

Well, the best part of this whole lighthouse experience continues to be all the great people we meet.

Today we met Ron Fiore, the structural engineer who devised the method of removing the gigantic First Order Fresnel lens back in 1975.

That lens blasted out a 3.2 million candlepower beam for 70 years straight. The lamp required a full-time crew to operate and maintain, so the Coast Guard had it taken out and replaced with an automated electric beacon.

Ron told us all the details about how he built a custom crane to gently lower the priceless lens – it weighed 2 tons and measured 12 feet tall and 9 feet across – down one story into the watch room.

Then he and the crew removed part of a wall to slide the lens past the sloping tower and drop it 60 feet to the dock, where a Coast Guard boat plucked it onto the deck. 

Legendary New England maritime history author Edward Rowe Snow made an appearance, instructing the crew to wave (as he was filming the feat) but the workers were too busy – and scared – to respond.

The next year Ron and his wife visited the lens again, this time at the Smithsonian!

The Fresnel lens was made in France by Barbier, Benard & Turenne in 1904, and was installed in 1905. After the 1975 removal, the Coast Guard installed an automated electric beacon, powered from land by an underwater cable. That cable broke, so in 2001 the Coast Guard installed the present solar-powered lamp, the Hydrosphere Vega VRB-25, made in the U.K.

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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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Glass jewels for lantern room get cast on Nantucket

Getting the glass jewels ready for the Watch Room skylights/Lantern Room floor panels.

Alison MacDonald of ACKfire studios gets the replacement glass jewels ready for the Watch Room skylights/Lantern Room floor panels.

We’re getting down to the fine details now. The missing glass jewels that form the skylights for the Watch Room ceiling and the floor pieces for the Lantern Room are now being cast.

The Nantucket artisans at Ackfire Studios are hard at work right now creating replacements for the missing heavy glass jewels embedded in the round bronze skylight frames.

Alison MacDonald of Ackfire visited Graves Light in April to examine the job and take measurements.

Now, the colored glass disks have been cut and are being cast in tiny molds within a large kiln.

We love our local artist community! Here is the Ackfire crew cutting individual discs of glass which will be melted and formed in these little molds.

The resulting glass jewels will be glazed into the lantern floor this month.

These glass pieces are reproductions of the missing original glass from the 1903 architectural design, and are copied from the remaining originals.

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Restoring the glass skylights

Alison works on a skylight. She's in the Lamp Room, looking down at the floor. The photographer is in the Watch Room, looking up at the ceiling.

Alison works on a skylight. She’s in the Lantern Room, looking down at the floor. The photographer is in the Watch Room, looking up at the ceiling.

Without a doubt, the most beautiful feature of Graves Light is the lantern, the glass room which housed the great Fresnel lens.

Built into the cast metal floor are 13 little round skylights that were the sole source of natural light for the Watch Room below.

The years have been kind (the heavy glass has turned from clear to a purply sun-colored amethyst) and unkind (several of them are missing or broken).

Not a problem for Alison MacDonald of ACKFire Studios.

Using one carefully removed glass tile, Alison has created a mold in her Nantucket glass studio and is busy reproducing the missing pieces.

We hope to report that by end of summer, the skylights will be fully intact again and ready for the next century of use.

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Authentic replacement windows restore original design

Karl Phillips of Driftwood Construction in Nantucket looks at how he's going to install the white oak casement window he built to restore the Graves Light windows to their original appearance and function.

Karl Phillips of Driftwood Construction in Nantucket looks at how he’s going to install the white oak casement window he built to restore the Graves Light windows to their original appearance and function.

From a rotted original casement window frame, master carpenter Karl Phillips and his friend Will Phelps built nine replacements in his Nantucket workshop, and installed them at Graves Light in early August 2014.

First we removed the historically inaccurate and aesthetically displeasing block glass windows that the Coast Guard installed decades ago to replace the originals, and then installed the casements.

Part of the installation was filmed for “This Old House.”

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