A 50-kilogram anvil floats perfectly on the surface of mercury, because the density of the steel from which it is made is almost half the density of mercury.
damn that shit is light lmfao
Fun fact! Many lighthouses with especially large fresnel lenses would have huge fucking tubs of liquid mercury in the lantern room because it’s a super easy way to make these giant lenses rotate quickly!
Shockingly, however, spending most of your time in close proximity to 500 pounds of liquid mercury is Not Great For One’s Health and tons of lighthouse keepers started to go crazy from the whole. Mercury poisoning thing. Hence why there are a lot of “haunted” lighthouses or wickies that lose it and maybe do a bit of manslaughter.
Anyway, people saw a bunch of lighthouse keepers go crazy and get sick and got empirical evidence that it was in fact related to the 500 pound mercury bath they have to visit every day and then they decided nah it’s fine actually. So we’ve kept the liquid mercury thing and I think that’s beautiful
I love how it is so dense it does not "wet" the anvil, the drops all run and leave with nothing behind them unlike water, oil, sauce... it's super satisfying it's like in cartoons
In a letter written on April 19, 1825, Augustin Fresnel proposed the use of mercury to reduce the friction in revolving lenses. His statement follows: “I propose to float our rotating devices, of the first order, in a bath of mercury, instead of placing them on rollers. This project won't present many difficulties; nevertheless, as I have not put it into execution, I won't require you to adopt it for your first lighthouse.”
Fresnel’s plan for mercury flotation was not put into practice until 1890 when Monsieur Leon Bourdelles, Chief Engineer of the French Lighthouse Service, designed and built a workable mercury flotation system. The mercury bath allowed the lens to operate in an almost frictionless environment and, additionally, allowed the speed of rotation to be dramatically increased.
Lens Rotation by Thomas Tag | United States Lighthouse Society
Ah to be a sailor in 1890 who has to turn to his fellow men and ask "is it just me or are the lighthouses flashing faster?"
They had been slowly getting faster for decades.
It mattered for optics reasons.
Under less-than-ideal conditions, you can only see the beam when it’s pointed more or less directly at you. In-between beams you would not be able to see anything. One solution to this was to create multiple beams, and the lenses Mr Fresnel designed usually created 8 beams. But, even still, duration between flashes could be as long as one minute in the old mechanical roller systems.
The nearly frictionless operation of the Mercury suspension system allowed the lenses (large pieces of precisely ground glass weighing several hundred pounds in some cases) to rotate fast enough that they could be redesigned to create fewer (usually 3) beams. Fewer beams from a similar light source will be proportionally brighter, and the gains in speed were sufficient that duration between flashes could still be reduced to as little as 10 seconds.
This was a big upgrade. It didn’t just make the lighthouse signal faster, it allowed them to completely overhaul the lens and derive more visibility from a light source.
What’s a little Madness, in the face of Progress?
mods are asleep, post the fresnel lens
