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Adding and Subtracting Machine

Description: Patent for an improved adding and subtracting machine adapted to be attached to the end of a lead pencil. It is readily manufactured and simple in construction.
Date: September 21, 1918
Creator: Wittnebert, Duke
Partner: UNT Libraries Government Documents Department

Crossing-Gate.

Description: Patent for improvements to crossing gates through a device that helps facilitate the gates' automatic closing and opening position.
Date: September 18, 1917
Creator: Hood, Lemuel L.
Partner: UNT Libraries Government Documents Department
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