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Image: Fleming Valve - US Patent 803,684
![Fleming Valve - US Patent 803,684](/images/thumb/5/53/Fleming_Valve_-_US_Patent_803%2C684.jpg/358px-Fleming_Valve_-_US_Patent_803%2C684.jpg)
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Description: United States Patent 803,684; first sheet. Illustrations of the 'Fleming Valve', the first useful vacuum tube. John Ambrose Fleming, inventor.
Title: Fleming Valve - US Patent 803,684
Credit: United States Patent Office.
Author: United States Patent Office (John Ambrose Fleming, inventor).
Permission: Public domain - original work of the US Federal Government. Note that the text and figures of all US Patents are in the public domain.
Usage Terms: Public domain
License: Public domain
Attribution Required?: No
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