Work and World

The Invention That Fixed Lighthouses

barnegat light a town on the coast of new jersey had a reputation in the 1800s it was the graveyard of the atlantic it had fast currents sand bars that shifted and shoals hidden ridges that wrecked ships but this narrow passage was crucial for tons of traffic from europe the result was wreck after wreck after wreck after wreck the lighthouse was intended to guide ships away from land it didn’t and a lot of lighthouses around the world had the same problem the problem at barnegat was the light inside that lighthouse it just wasn’t strong enough and the solution was an invention that fixed lighthouses from france to florida an international upgrade that’s still in use today and is used in things like this the lighthouse wasn’t enough to save ships [Music] they needed the right lens i volunteered at the saint augustine lighthouse here in florida it was in 1992 so it was a while back [Music] and i saw the fresnel lens and it was just beautiful and i stood inside of this and i was surrounded by all these glass prisms and i was just intrigued by it and i wanted to know how it worked my name is dan spinella with artworks florida classic fresnel lenses and i’m a lens preservationist and designer i build historic reproductions of classic fresnel lenses and also build the prisms and lenses to help restore the original classic fresno lenses this is a fresnel lens the breakthrough that made lighthouses work like lighthouses should work light from a lamp is diffuse too weak for a ship to see it from far away a fresnel lens fixes that it takes that light and using prisms redirects and magnifies it in one unified direction see how this light and this light both go the same way a candle becomes a spotlight this is a fresnel lighthouse with bullseye panels in the middle and those look like lights a lot of people use in lighthouses and everywhere you know i have a light fresnel that i attached to my my little spotlight up here should be pretty much the same thing right yes it is it’s it’s identical in design and that’s what’s amazing about it is something that was designed in 1819 is still being used today i normally attach this to a light to make a spotlight but it is a fresnel when i light a candle it takes that light and focuses it into a spotlight and so the light gets more intense the brighter i make it or in this case the closer i hold it to the center of the lens the same thing happens when i use my phone the fresnel captures all of that light and focuses and magnifies it these lenses weren’t just an improvement they created a whole system that saved lives agustin jean fernell an engineer and physicist was part of a french lighthouse commission to improve lighthouses developed through the 1820s vernell’s lens proved better than existing lights including the ones at barnegat probably tens of thousands of wrecks are scattered throughout the barnegat shoals and up and down that area of new jersey uh there were a lot of flaws with that lighthouse they were called lewis lights the lewis lamp was successful in so far it was better than nothing however the technology was flawed it was lacking like many lamps at the time a lewis lamp used a reflector to catch light it had a small lens to project that light but a lot of light escaped it wasn’t bright enough so they weren’t as efficient and the metal wasn’t as efficient because it absorbs a lot of the light that’s why the design of the fresnel lens was so much more efficient that it collected more of the light and directed at seaward what it’s supposed to do in addition to strengthening and magnifying light fresnel’s flashing with rotation turned them into a communication device so it creates this flashing characteristic even though the lamp is continuously on it was a flame you couldn’t turn it off depending on how they design the lens it creates different flashing characteristics so you knew where you were at what location you were at before gps colored panels or even colored flames could make lights more distinct some got huge a first order fresnel was this big more than 75 fresnels are still up and running today in the united states alone thanks to these lenses that rippled across the globe lighthouses cast light farther communicated more information and saved lives [Music] the lighthouse is a wonderfully strange 2019 movie in which a fresnel is so hypnotic willem dafoe’s character undresses and bathes in its light the director called it the cosmic egg with the production designer dan spinella made the lens in the film i had to work a lot of hours i probably worked 14 16 hour days for eight weeks straight seven days a week i didn’t take any breaks i got it done just in time probably five days before filming i was creating it up i had to drive it up to nova scotia from florida it’s sort of a weird showcase for your work because it’s it’s sort of the most flattering possible look for your work but in a really weird movie it’s definitely not a feel-good hallmark movie that’s for sure i mean i i like the fact that the focus was on the lens and you didn’t i liked the little sneak peaks of the lens until you got to the very end of the movie they actually actually saw it it was almost a star in the movie itself they did a really good job getting everything historically accurate the very first lens that i worked on the saint augustine lighthouse when i started designing that lens on the computer i was just amazed at how the formulas were actually working and to think that they did that in the 1800s and they went to these formulas and the same thing i was doing now crashes still happened at barnegat even after they added a fourth order for now the lighthouse was small and the sea was dangerous but in 1857 they built a new lighthouse and it was crucial that they have one thing in it they got a fresnel lens and not just a fresnel lens the biggest one that they built which was a first order lens the mariners were very grateful for because it did save lives because unlike the lewis light this could shine out at least 20 miles they really don’t know how far it could shine because the curvature of the earth but that’s how powerful it is what they did to rotate the lenses they used a clockwork mechanism they didn’t have electricity they didn’t have electric motors they used a clockwork mechanism which is very similar to a grandfather clock there’s a weight that would drop down the center of the lighthouse and that weight was attached to a cable which was wrapped around a drum and that drum had a gear on the end of it and that gear drove a series of gears inside the clockwork mechanism and that determined by the ratio of the gears determined the speed at which the the lens would rotate it engaged with a gear that was underneath the bottom of the lens the lens was on either chariot wheels ball bearings or in some cases it was a mercury bath that allowed it to rotate so that was built as a demonstration for the pensacola lighthouse
Video source: https://www.youtube.com/watch?v=8z0l0yjBFmo

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