Wanted: Hatfield Adder
This Hatfield adder was invented and manufactured by Aaron L. Hatfield of Lewisburg, Pennsylvania. Patent no.11,729 was issued to Aaron on September 26, 1854. The Hatfield is a circular adding machine consisting of 3 concentric brass discs and a brass lever mounted to a wood paddle. A paper label instruction sheet was glued to the rear. There were two version produced though both operated similarly.
Hart's Mercantile Computing Machine was a similarly-functioning, paddle-mounted device.
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