Comptometer Model A
1904 · Key-Driven · Work 423 of 1,871
A key-driven adding machine in a dark lacquered metal case, eight columns of round keys rising in a stepped bank from front to back, each key cap bearing exactly one digit from 1 to 9, a metal plate at the front edge with a strip of small result windows, each window showing the single digit 0, every other surface plain dark lacquer and dull metal, a metal plate on the front edge reading "Comptometer", standing on a dark baize-covered table before a deep neutral background, a single raking light from the left raking across the stepped bank of keys.
- What it was used for
- A key-driven, non-printing adding machine by the Felt & Tarrant Manufacturing Company of Chicago. The Smithsonian describes its example no. 17536 of 1904: metal case, eight columns of plastic keys colour-coded for money calculation, nine number wheels behind glass, ten patent dates on the plate. On John Wolff's account the Model A was built from 1904 to 1906. It was used wherever columns of figures came in: the Smithsonian names government offices, businesses and observatories among the buyers. The machine adds as the key goes down; it prints nothing, the result stands in the windows and has to be read off and copied out.
- What was new
- The Model A was the first Duplex machine of the series: the Smithsonian and John Wolff record that keys in adjacent columns could be pressed at the same time, so that a multi-digit number could be keyed in one movement - which the earlier wooden-box models could not do. The full keyboard itself was not new; the wooden-box models already had it. The basic design already kept incomplete keystrokes from registering; but the Model A had as yet no device that detected such errors and locked the machine. John Wolff dates that controlled key to the Model E of 1913 and calls it the first machine with an automatic mechanism to detect and correct incomplete keystrokes - nine years after the Model A.
Connections
Every connection names its kind. “Forerunner” on its own would be a claim.
- Follows fromThe Macaroni Box1885Dorr E. Felt made his first crude model in 1884-85 from a macaroni box from a local grocer, with meat skewers for key stems and with rubber bands. The Smithsonian records the box as the prototype of the Comptometer. The Model A, produced from January 1904, is an early example with a metal case and Felt & Tarrant's first 'duplex' machine.Source: Smithsonian NMAH, Adding Machines: Full-Keyboard - Hill to Felt & Tarrant