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The Second Whittemore and Petrenko's Patent

On August 24, 1929 Whittemore and Petrenko filed for a second proving ring patent with the United States Patent Office. The drawings contained with the patent are shown below. They include improvements in the design of the proving ring.


Whittemore and Petrenko's Patent


Whittemore and Petrenko's Patent


Created September 11, 2009, Updated November 25, 2019