Arc Lamps
By Charles Brush
Yes, there were electric lights powered by central stations before Edison's! Carbon arc lamps saw extensive use throughout the USA and the world from the late 1870s on. Due to their intense light they were not that practical for lighting small interior spaces. However even after the advent of the incandescent bulb, arc lamps survived for decades being used as streetlights and for lighting large interior spaces like factories, mills, and department stores. Early incandescent lamps produced about 16 candle power, while arc lamps produced 2,000-4,000 candle power. Incandescents just didn't have the output or efficiency of arcs. Today carbon arcs are still used in some large spotlights and projectors.zdssdAaswewssdq
Arc lamps come from almost the exact historical point when electricity went from being a scientific curiosity to being part of everyday life. This was a time of horse-drawn carriages and gaslights, when the Civil War was just over ten years in the past. For many people an arc lamp was the first electrical device they had ever seen. In the late 1870s a lone arc lamp in a store window (powered by its own little dynamo) could draw large crowds. This was the first and most visible manifestation of a wave of technological development that would rapidly and forever change the world. With electric light came the centralized power distribution that would not only power cities and towns, but would provide the motive force to allow industry to thrive. By the turn of the century electric lights were more commonplace, and companies like General Electric were making tens of thousands of arc lamps a year. Despite this, they are surprisingly hard to find. I got interested in collecting these lamps because of my great grandfather's role in their history, but have yet to find either a lamp or dynamo made by his company. I think it would be fascinating to recreate the type of small light plant commonly used in the 1870's. It's always great talking to others interested in early lighting so feel free to contact me!
A self adjusting mechanical lamp using a superheated plasma to produce light is a pretty interesting idea. Now think of these lamps being in widespread use when incandescent lightbulbs were still experimental. Think of seeing one for the first time when you knew nothing of electricity, and the brightest artificial light you had ever seen before was a flickering gas or oil lamp.
Imagine what it was like 125 years ago...
Broadway New York City 1881
How do arc lamps work? Well two carbon rods connected to a current limited source are brought together and then drawn apart. As the carbons separate, a hot ionized path is created between them (the arc) that continues to conduct after the carbons have been separated. This arc burns at thousands of degrees and heats the ends of the carbons to incandescence. Most of the light comes from the tips of the carbons, not the arc itself. As the carbons burn down they need to be constantly adjusted to maintain the proper spacing so that the arc does not go out. Part of what is fascinating about early lamps is the range of ingenious mechanisms that were used to do this. Everything from manually adjusted designs to complex clockwork mechanisms were tried, and as you might guess reliability became a major issue. One design overcame this hurdle and became commercially successful by the late 1870s ushering in the era of electric light.
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