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March 13 Patent of the Day

Posted on March 13, 2016 by bwheelock

On March 13,. 1877, U.S. Patent No. 188,292 issued to Chester Greenwood on Ear-Mufflers:

March 13

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About bwheelock

Education J.D., Washington University in St. Louis B.S.E. in Mechanical Engineering, Duke University
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