Cardborad Disc

Cardborad Disc

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William J. Hammer (1858-1934) began working with Thomas Edison in 1879, assisting in the development of the incandescent light bulb. In time he was known as an electrical engineer and expert on electric power distribution. Other interests included radium, selenium cells, aeronautics, and the transmission of sounds. This cardborad disc is part of his apparatus for measuring light.
Ref: William J. Hammer, “Method of Measuring Light,” U.S. Patent 333,308 (May 26, 1908).
Currently not on view
Object Name
cardboard disc
overall: 1/8 in x 24 in;.3175 cm x 60.96 cm
ID Number
catalog number
accession number
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Medicine and Science: Physical Sciences
Data Source
National Museum of American History
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