comptometer
Date: circa 1935
Inventory Number: 1998-1-0636
Classification: Calculating Machine
Subject:
Maker: Felt and Tarrant Manufacturing Company (1887 - 1957)
Cultural Region:
Place of Origin:
Dimensions:
14.5 × 24 × 37.8 cm (5 11/16 × 9 7/16 × 14 7/8 in.)
DescriptionComptometer is encased in a brown metal rectangular case. There are seven columns of nine buttons each centered on the top face of the case. Each button consists of a rounded cap with a flat metal base that goes into the brown case. The two leftmost and the two rightmost columns of buttons have yellow caps and the central three rows have green caps. Each button has two black numbers etched into it. One set of numbers is larger than the other. The large numbers begin with 9 at the top of each column and decrease incrementally to 1 at the bottom. The smaller numbers beginning with 0 at the top of each column and decrease incrementally to 8 at the bottom.
At the bottom and to the left of each column of buttons is a small round black disc with a metal number stamped on it and a small metal arrow pointing downwards. The numbers begin with 7, beneath the leftmost column, and decrease incrementally to 1 beneath the rightmost column. Above each black disc there is a flat metal lever in a small track cut out of the surface of the case. Beneath each disc, toward which the small metal arrows point, is a round window through which a white numeral from 0 to 9 is displayed on a black background. The levers are meant to reset each column. There is an extra numeral display window all the way to the left of the display row. There is an extra metal lever all the way to the right of the lever row. Above this lever, in an eighth column to the right of the regular buttons, are four additional buttons. The bottom three are of the same size and shape as the numeral buttons, all have green round tops. They are labeled 1/4, 1/2, 3/4, from the bottom to the top. A fourth button above these three is shorter than the rest and has a round red cap. A metal lever with a black handle is attached to the right-hand side panel of the instrument.
For more technical information, see the 1935 patent here.
At the bottom and to the left of each column of buttons is a small round black disc with a metal number stamped on it and a small metal arrow pointing downwards. The numbers begin with 7, beneath the leftmost column, and decrease incrementally to 1 beneath the rightmost column. Above each black disc there is a flat metal lever in a small track cut out of the surface of the case. Beneath each disc, toward which the small metal arrows point, is a round window through which a white numeral from 0 to 9 is displayed on a black background. The levers are meant to reset each column. There is an extra numeral display window all the way to the left of the display row. There is an extra metal lever all the way to the right of the lever row. Above this lever, in an eighth column to the right of the regular buttons, are four additional buttons. The bottom three are of the same size and shape as the numeral buttons, all have green round tops. They are labeled 1/4, 1/2, 3/4, from the bottom to the top. A fourth button above these three is shorter than the rest and has a round red cap. A metal lever with a black handle is attached to the right-hand side panel of the instrument.
For more technical information, see the 1935 patent here.
Signedembossed on metal plate on instrument face: Felt & Tarrant Mfg Co. / CHICAGO
Inscribedembossed in columns on metal plaque at top of instrument: PATS. / 2,020,975 / 1, 357, 748 / 1,357,747 / 1,110,734 / 1,072,833 / 1,066,096 / 1,003,723 / 992,950 / 960,526 / 789,099 / 762,521 / 762,520 / 733,379 / 371,469 / 366,945
in black letters on front edge panel of instrument: Comptometer
in black letters on front edge panel of instrument: Comptometer
FunctionThe Comptometer is an early, keydriven mechanical calculator that enjoyed commercial success. This instrument was primaraly desiged to perform addition but with certain extra steps could also perform subtraction, division and multiplication. Many similar models do not have the fraction buttons visible on this machine.
A discussion of the history, functioning, and significance of the Comptometer is available here or here.
A discussion of the history, functioning, and significance of the Comptometer is available here or here.
ProvenanceFrom the Museum of Comparative Zoology Library, Harvard University.
