Actually, this is not a great explanation of a Fresnel lens. While the bulls eye might look prism-like, it works through refraction. It is a Dioptric lens, that has been cut into concentric circles and the bulk of mater removed to create a much lighter and smaller form factor. The extra glass surrounding are prisms and they reflect (Catoptric) and collect extra light that would otherwise be wasted. Together they make a very efficient and most importantly, lightweight way of producing a concentrated beam of light. It is known as a catadioptric system.
Were the lighthouse keepers aware of the toxicity of mercury? I can remember our whole elementary school science class being encouraged to touch it and let it roll around in our hands (1970's). The danger wasn't realized at that time.
Watched the Wolf Rock lighthouse in Series 2 & I was expecting to see the process in building it & there wasn't one bit of it, yes the rest was interesting but surely 15mins could have included this Rob, I mean what a feat in an area that is rarely becalmed & we won't know of it.
But the lighthouse bulb was still heavier than 25 pints of mercury why didn’t it spill out and the bulb go down to the bottom ? Was it under pressure ?
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I always wonder what was inside a light house the bulb and all. Thanks for sharing.
A Phenomenal Well Put Together Video All The Best To All The Team.
Actually, this is not a great explanation of a Fresnel lens. While the bulls eye might look prism-like, it works through refraction. It is a Dioptric lens, that has been cut into concentric circles and the bulk of mater removed to create a much lighter and smaller form factor. The extra glass surrounding are prisms and they reflect (Catoptric) and collect extra light that would otherwise be wasted. Together they make a very efficient and most importantly, lightweight way of producing a concentrated beam of light. It is known as a catadioptric system.
Exactly so.
awesome explanation
It's quite interesting. Human overcomes natural force to build lighthouses. 😀
Were the lighthouse keepers aware of the toxicity of mercury? I can remember our whole elementary school science class being encouraged to touch it and let it roll around in our hands (1970's). The danger wasn't realized at that time.
The biggest problem with mercury is its fumes.
Watched the Wolf Rock lighthouse in Series 2 & I was expecting to see the process in building it & there wasn't one bit of it, yes the rest was interesting but surely 15mins could have included this Rob, I mean what a feat in an area that is rarely becalmed & we won't know of it.
The Lighthouse movie brought me here.🙂
Anyone here after Max Millers video of Lighthouses?
Came here after saw The Lighthouse movie. lol
Me too
I would like to work there, with a Xbox, a dog, food, WiFi and lets go and Air Con.
Where is the rest?
Just to get you to sign up to a scam site!
Give us a break.
It's not a scam site but showing a preview of the episode.
First
But the lighthouse bulb was still heavier than 25 pints of mercury why didn’t it spill out and the bulb go down to the bottom ? Was it under pressure ?