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Most of the photos on this site were extracted from reference images (high-resolution tiffs, 20 to 200 megabytes in size) from the Library of Congress research archive. (To query the database click here.) Many were digitized by LOC contractors using a Sinar studio back. They are adjusted by your webmaster for contrast and color in Photoshop before being downsized and turned into the jpegs you see here.

 
 
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VINTAGRAPH • WPA • WWII • NORTH TUSCANY COAST, 1948

Desk Lamp: 1938

Desk Lamp: 1938

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. View full size.

 

Henceforth

... the $45 light bulb!

Integration

The 'ball' is an Integrating Sphere, used to measure the various characteristics of light sources, especially 'power output' - luminous intensity, etc.

The device is painted inside with very carefully controlled reflective paint, and the optical radiation (infra-red, visible, or ultra-violet) from a test lamp can be measured with photocells, etc., without regard to what portion of, and what direction, the energy is coming from.

If you wished to measure the water flow from a lawn sprinkler, but only had a small cup to use, the measurement would be very inaccurate because only the streams coming toward you would go in the cup, the rest would be 'lost' on the lawn. So you'd have to move around the entire spray pattern in a known and timed manner, take lots of small measurements, and factor all that in, -OR- you could just put the whole sprinkler in a closed box with a single drain, and do your flow measurements using that.

The integrating sphere does this for light sources, it 'collects' (integrates) the output in a known and controlled way, and eliminates directional errors.

http://en.wikipedia.org/wiki/Integrating_sphere

Although primarily an electronics engineer, I have done some work with illumination systems, and still have the small sphere I bought surplus years ago on my shelves, along with the other piles of "stuff".

As for the exposed knife switches and variable resistors (the long round tubes with sliding knobs on the top) - yeah, that was pretty dangerous - and all the circuits were two-wire, no real grounds from the mains... you had to be careful and pay attention or your gear taught you a lesson. :)

Lumen Counter

Obituaries, Washington Post, Nov 24, 1986

Louis E. Barbrow

81, a retired chief of the National Bureau of Standards optics metrology branch, died Nov. 20 at Providence Hospital after a heart attack. He lived in Washington.

Mr. Barbrow was born in Pittsburgh. He earned a degree in physics from Carnegie Institute of Technology in 1926. He moved to the Washington area in 1927 and joined the NBS, where he specialized in measurement [of] radiation, light and color.

He had served as chief of the photometry and colorimetry section and was chief of optics and metrology when he retired in 1969. In 1967, he was secretary of the U.S. delegation to the International Conference on Illumination.

Since retiring, he had been a consultant to the NBS Office of Weights and Measures.

Mr. Barbrow was a Mason, a past chairman of the American National Standards Committee, a past secretary of the metric practice committee of the American National Metric Council, and a member of the metric advisory committee of the Society of Automotive Engineering.

Survivors include his wife, the former Blanche Wallace of Washington, a daughter, Jane Lobl of Pittsburgh, and three grandchildren.

A shocking experience

Judging by all the bare wires and exposed splices, one could have an enlightening experience even without a light bulb.

The dark sphere reminds me of the sci-fi movie The Fly.

Idea Man

This guy obviously has many good ideas just waiting to be developed for cartoon characters.

 
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Shorpy.com | History in HD is a vintage photo blog featuring thousands of high-definition images from the 1850s to 1950s. The site is named after Shorpy Higginbotham, a teenage coal miner who lived 100 years ago.

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