Most people think Thomas Edison invented the electric light. Nah. Edison invented the incandescent light bulb, but electric lights were invented about 70 years earlier by Sir Humphrey Davy. His device was (and is) called an Arc Light.
Arc lights are extremely bright. Not particularly efficient mind you, but they are certainly bright. When I was going to high school in the 70s, there were arc light movie projectors in the school auditorium.
WWII style searchlights were arc lights as well. Each search light piercing the night sky over London searching for Stukas and Junker bombers were the equivalent of a 13,000 watt incandescent bulb and were able to throw a beam on something five miles away.
Click above on the picture above or browse to http://www.youtube.com/watch?v=wY06G2iSR8M for a video of an arc light I made that uses carbon rods from a non alkaline battery and a 12 volt transformer. The video shows how it's made and more info is available in an upcoming issue of Make Magazine.
Note: If you make one, don't look directly at the arc without eye protection -- avoid the UV rays
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Arc lights give off substantial amounts of UV, looking at an unfiltered arc light can actually harm your vision. I've built a few, and love'em dearly, but take precautions with your eyesight if you work with them. There was a whole industry in figuring out clockwork mechanisms to keep the carbon rods consistently spaced as the arc ran, there are great patents on it you can look up.
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