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Thursday, April 16, 2015

Carbon Arc Lights

Three videos for your amusement. Special for Roberta X.

Posthip Scott sent me a link to a page which included this video of a WW2 anti-aircraft searchlight. They don't actually turn the light on here, this video just demonstrates the remote control. Not a big deal now, but a bit of a trick before the advent of digital electronics. Not to mention big, expensive and power hungry.

Carbon arc lights used to be used in commercial movie projectors. If you ever seen one they look like huge pieces of complicated equipment. They are, but the bulk of the machine is the big, empty chamber for the arc light.

You would want to be careful of your eyes when you start the arc. Too much looking at bright lights can blind you. We know this because it used to happen to captains of sailing ships because they used to take sightings of the sun to navigate. Funny, I remember being warned, rather severely, about this: don't look at directly at the sun, it will blind you. Hard to imagine that there was once a time when people didn't know that. I mean, it's painful to look at a bright light, I wouldn't think anyone would be able to look at the sun long enough to cause any damage. Perhaps there is some deer-in-the-headlights reaction that forces us to look?

This one gives a bit of history of arc-lights. It's not a great video, but it's not too painful either. When I was in Austin, Texas, back around 1980, they still had several 'moon towers' scattered around town. They are 150 feet tall and originally employed carbon arc lights for illumination. The had no lights at all when I was there. Evidently they do now.

I never used to be impressed by General Electric. The principles involved in their products were so elementary as to not even warrant consideration. General Electric's trick, that I didn't appreciate at the time, was packaging up these elementary principles in machine that people could use. It wasn't especially complex, but there were a lot of little details that you had to get right or the product would be a flop. Details that I thought were obvious, but like so many things they weren't obvious to everybody.

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