How A Lighthouse Works | The Secret Life of Lighthouses | Channel 5

[@lejonfo]

I always wonder what was inside a light house the bulb and all. Thanks for sharing.

[@neilurwin9670]

A Phenomenal Well Put Together Video All The Best To All The Team.

[@ollyk22]

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.

[@yzScott]

Exactly so.

[@abhirupbasu6808]

awesome explanation

[@coops..41024]

It's quite interesting. Human overcomes natural force to build lighthouses. 😀

[@RusTsea196T]

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.

[@aronkovacs1386]

The biggest problem with mercury is its fumes.

[@seltaeb3302]

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.

[@klondikebelridge1996]

The Lighthouse movie brought me here.🙂

[@94rome]

Anyone here after Max Millers video of Lighthouses?

[@joejoe43200]

Came here after saw The Lighthouse movie. lol

[@watchguy7986]

Me too

[@kenofken9458]

It's interesting but maybe not the wisest idea to keep around, particularly in an enclosed space. Mercury is highly toxic, and while metallic mercury is not the most dangerous in terms of bioavailability, it produces vapors even at room temperature. Small amounts to be sure, but there is no known safe level of mercury. I can't imagine this would ever be allowed in the states. They've regulated mercury so tightly that they don't even allow it in small amounts for most applications. I remember even 20 years ago or more, commercial and university laboratories hunted down all the old mercury thermometers and removed them, often to the chagrin of chemists who considered them more reliable than newer technologies. The idea of having 25 pints of this stuff around would give the environmental compliance people fits.

[@who-gives-a-toss_Bear]

Where is the rest? Just to get you to sign up to a scam site! Give us a break.

[@seltaeb3302]

It's not a scam site but showing a preview of the episode.

[@davidsimplicio4676]

I would like to work there, with a Xbox, a dog, food, WiFi and lets go and Air Con.

[@charlieward5609]

First

[@watchguy7986]

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 ?

[@kenofken9458]

Mercury is enormously dense. More than 13 times as much as water and not quite twice the density of steel. If you had a box that was cube one foot in all dimensions and filled it with mercury, it would weight 845 pounds. It also has a very high surface tension. If you look around online, you can find pictures of big steel anvils floating on mercury and even one of a guy in industrial coveralls sitting on top of a big tank of mercury, with him sinking in it maybe just a couple inches.