A history of light

[Via Family first]

...an interesting look at the history of light. It veers all over the map in telling the story of light, and I think you'll find it fascinating.

It begins with the origin of the universe, as espoused by Immanuel Kant in 1755. We progress through the ages as man begins illuminating the night with crude torches, mastering the dark.

Eventually, we find our way to the nineteenth century, when electricity first began to be used for lighting. Obscure devices are recounted, including Alexander Graham Bell's
sunlight-transmitted telephone.

Stage lighting is given a special emphasis, and I found the saltwater dimmers used for adjusting the volume of
light to be amazing to read about. These devices consisted ofan electrode at the bottom of a tank of brine, and another electrode that was raised or lowered in the liquid to adjust the voltage going to the bulbs. The brine would boil, heating the backstage area.

Cool stuff.

See for yourself.