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1933 - Leon R. Ludwig demonstrating the pencil igniter of this mercury control tube

PENCIL LEAD CONTROLS ELECTRICAL ARC

CD 1967005 E&MP43.005

Electrical Engineering

MAY 17 1933

A pencil of lead has been found after 25 years of research, to be capable of initiating and controlling electric arcs.

The arc is started in less than five millions (5/1,000,000) of a second, Called the "ignitron", by its discoverers, Dr. Joseph Slepian and Leon R. Ludwig, research engineers of the Westinghouse Electric and Manufacturing Company, it is expected to revolutionize present methods of conversion and control of electrical energy.

Ludwig demonstrating the pencil "igniter" of this mercury control tube.

1933 - Ludwig demonstrating the pencil

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Dr. Joseph Slepian and Leon R. Ludwig, Westinghouse research engineers, witness a laboratory model of their "ignitron" control, which may revolutionize present methods of conversion and control of electrical energy.

1933 - controls currents a million times greater in an electric arc

By means of a tiny current applied to a pencil "igniter", they are able to control currents a million times greater in an electric arc.

1933 - Dr. Joseph Slepian and Leon R. Ludwig

Dr. Joseph Slepian (left) and Leon R. Ludwig (right) with "Ignitron"

It is said that this is comparable to controlling with the flip of a house wall switch the enormous current that would be required by all the homes and industries of a city five times larger than New York (City).

They recently demonstrated the new device at the American Institute of Electrical Engineers' convention in New York.  


Original Caption by Science Service
Westinghouse



National Museum of American History

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