Archive for December 27th, 2012

December 27, 2012

Lighthouse lights

Light bulbs in the Sea Girt lighthouse

In the northeast, we’re getting hit with some ugly wintry-mix weather (tho’ not nearly as bad as the system that hit you guys out west— ouch), and neither I nor my camera have the constitution to go take pictures of it.

So instead: you know what lousy stormy wintry-mix weather puts me in mind of? WARM SUNNY BEACHES.

…Of course, New Jersey’s warm sunny beaches all got washed away, which puts me in an entirely different state of mind, but that’s another story.

Anyway, the week before Sandy, I had the chance to climb up Sea Girt lighthouse.

Docents at the lighthouse were careful to explain that Sea Girt didn’t have a working light.
Some of us, confused, replied that we’d SEEN the light from Sea Girt lighthouse at night, it DID have a light, WTF.
The docents scoffed and said that yes, it had a sort of wimpy light source, but that light source didn’t actually DO anything. You can’t see the light from the SEA or anything.

So: the wimpy light from Sea Girt lighthouse is provided by this here setup: two 100-watt lightbulbs and a small prism.

For context, lighthouse lights are usually refracted by huuuuuuuuuuge prisms that… I dunno, focus the beams, I guess.

Here’s what the Fresnel lens inside Sandy Hook light looks like:

Sandy Hook light

And Sea Girt light’s museum has an example of the sort of Fresnel lens that was inside the lighthouse originally:

Sea Girt light's Fresnel lens. I wonder if it survived Hurricane Sandy? They paid an awful lot of money for that thing.

I guess it’s a fourth-order lens, which apparently refers to the size, and fourth-order is on the smallish side.

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