March 21, 1938. Washington, D.C. "Purchasing on an average of 4 million electric light bulbs annually, Uncle Sam is probably one of the largest users of light in the country. The National Bureau of Standards sees that the government gets value received in purchases by continually testing the incandescent lamps to determine their life and the amount of light they give. Using a special machine designed by the Bureau, Louis Barbrow is shown measuring the amount of light given by a lamp." Harris & Ewing Collection glass negative.
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