Comptograph

After inventing the Comptometer, Dorr E. Felt turned his attention to manufacturing a printing adding machine, which he dubbed the Comptograph. This early example is a full keyboard adding machine in a wooden case, with eight columns of metal keys covered with white discs. Each key stem has spring around it. Digits and complements of digits are indicated on the discs. In front of the keys are nine number wheels, visible through a glass window in a metal plate. The printing mechanism is at the back of the machine. Two large buttons, one on the right of the machine and the other on the left, are depressed to control this mechanism. The right button advances the inked ribbon to the take-up spool. What appears to be a zeroing knob and lever for the numeral wheels is at the front on the right, although it does not function. There is no paper tape. The section at the top of the machine that holds the metal tape folds over to protect the printing mechanism when not in use. A wire tray can be positioned to hold the paper tape.

The machine is marked with the serial number in the middle of the front and on the mechanism in the back right. this is: 209. A metal tag attached to the right side of the object reads: COMPTOGRAPH (/) PATENTED (/) JULY 19. 87. 366,945 (/) OCT. 11. 87 371,495 (/) JAN. 8. 89. 396,034 (/) JUN. [. . .] 89. 405,924 (/) NOV. 25. 90 441,232 (/) 441239 (/) It also reads: FELT & TARRANT MFG. CO. (/) 52 - 56 ILLINOIS ST. (/) CHICAGO. It also reads: COMPTOGRAPH (TRADE MARK).

References:

J. A. V. Turck, Origin of Modern Calculating Machines, Chicago: Western Society of Engineers, 1921, p. 119.

E. Martin, The Calculating Machines (Die Rechenmaschinen), trans. P. A. Kidwell and M. R. Williams, Cambridge: MIT Press, 1992, p. 104 ff.

Currently not on view