71.9

Comptometer

1940 Approximate

Comptometer Adding Machine. Material: metal. Size: 9" W. x 14 1/2" H. Description: green metal case; silver nameplate at top: "Felt and Tarrant Manufacturing Co Chicago U.S.A."; white and green keys in center; numbers on each key; eight small buttons in same color sequence across bottom; nine windows at bottom; final changeable figures appearing; silver metal handle on right side; printed on front: "Comptometer"; silver metal plate on bottom: "Patents in the United States N. America" three columns of patent numbers listed below.

Waseca business: Swift & Co. Comptometer used at Swift & Co. for bookkeeping. A Comptometer is a type of mechanical (or electro-mechanical) adding machine. The comptometer was the first adding device to be driven solely by the action of pressing keys, which are arranged in an array of vertical and horizontal columns. Comptometer is, strictly speaking, a trade name of the Felt and Tarrant Manufacturing Company of Chicago (later the Comptometer Corporation), but was widely used as a generic name for the class of device. The original design was patented in 1887 by Dorr Felt, a U.S. citizen. Although the comptometer was designed primarily for adding, it could also do division, multiplication and subtraction.