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American Electric/Thomson-Houston
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Lamp as found.
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Original appearance.
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First Lighting in 100+ Years
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American Electric open arc lamps manufactured under Thomson-Houston patents
These lamps are each about four feet tall, solid iron, and each weighs a considerable amount. The tube extending out the top Lamps like these could produce between 2,000 and 4,000 candle power. In 1880 Wabash Indiana had used just four Brush lamps of similar design to light the entire town and earn itself the title of first city anywhere to be wholly electrically lit. Remember that this was a time when gas and kerosene lighting were common. Incandescent lamps were just starting to show up in a few cities for indoor lighting, but could only produce about 16 candle power Carbon arc was a proven and established technology, and remained the brightest artificial light source until fairly recently. The photo on the right shows the first lighting of this arc lamp in probably well over 100 years. The last time this lamp operated was in a world of gas lamps and horse drawn carriages. At the time most people had never seen an electric light before. Just imagine what it would have been like to see a 3,000 candle power arc lamp when all you knew were relatively dim gas and kerosene lamps. In this shot the camera's lens flare exaggerated the arc. Here the lamp is being powered by a very simple current limited DC power supply, and the cover is off the lamp mechanism. |
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This lamp is wired for series operation and uses a differential design with two opposing sets of electromagnets. Note the rocker mechanism on the far right. It looks sort of like a see-saw. When power is applied to the lamp, the lower pair of electromagnets pull this rocker towards themselves. The rocker is attached to a clutch which grabs the upper carbon an pulls it upwards away from the lower carbon. On the lower left between the two bottom electromagnets you can see a squat metal tube. This is the dashpot, and its role is to dampen the pull on the upper carbon so that it does not suddenly jerk away from the lower carbon.
This photo shows one of the lamp's internal mechanism as it was found. It would actually not be operational as you see it here because it had been intentionally shorted out. That spring you see on the left has been removed from it's original position attached to the rocker, and instead has been soldered across the two power leads feeding the mechanism. Perhaps at some point the circuit that these lamps ran on was upgraded to a newer incandescent system, and for some reason these lamps were left hooked up, but bridged so that they would not longer operate. At any rate, after the spring was de-soldered and put back where it belonged, this lamp ran beautifully as shown above.
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![]() Detail of lower carbon holder and globe holder. |