Adding MachinesFull-Keyboard – Hill to Felt & Tarrant
In the mid-19th century, the Unitarian minister, mathematician and inventor Thomas Hill envisioned an adding machine that would have a column of keys for each digit entered. Hill took out a U.S. Patent for the device, but it never became a practical product.
Almost thirty years later, Chicago machinist Dorr E. Felt (1862-1930) decided to design an improved adding machine for accountants. Like Victor Schilt, he was interested in adding machines with keys, but he wanted to add larger numbers and to add them quickly. To do this, he devised a machine with several columns of keys. In each column, the keys were numbered from 1 to 9. The column as a whole represented one digit of a number. Felt first made a crude model using a macaroni box from a local grocer, with meat skewers for key stems and rubber bands for screws. He built several prototypes of the machine, and named it the Comptometer. Felt also soon built a printing version of the machine, which he called the Comptograph. It never sold widely.
On Felt’s Comptometer, pushing a key not only set up a digit, but entered it into the mechanism. Felt carefully cultivated customers, and won the financial support of Robert Tarrant as well as orders from government offices, businesses, and scientific observatories. Felt & Tarrant Manufacturing Company sent its products overseas as well as across the country. It built special Comptometers for adding fractions and non-decimal currency, and steadily improved, but did not radically alter, the product. Felt & Tarrant used some of its profits to acquire adding machines of historic interest.
Felt died in 1930. After considerable debate, descendents of Felt and Tarrant decided to take the firm public in 1946, taking the name Comptometer Corporation. The postwar years proved difficult, especially for foreign sales. In 1961, the firm merged with the Victor Adding Machine Company of Chicago to form Victor Comptometer Corporation. The products of this company looked quite different from those of Felt & Tarrant, as they were ten-key, printing machines. Not long thereafter, Victor Comptometer donated Felt’s collection of historically important machines to the Smithsonian.
"Adding Machines - Full-Keyboard – Hill to Felt & Tarrant" showing 1 items.
- This key-driven non-printing adding machine has a metal mechanism, steel keys with German silver and plastic key tops, and steel dials at the front that record the result. It is a production model of the Comptometer made by Felt & Tarrant Company of Chicago during its early years.
- The eight columns of keys have nine keys each. Celluloid discs in the key tops are color-coded to mark off dollars and cents. Complementary digits are indicated on the discs, to aid in subtraction. The key tops are alternately concave (odd digits) and flat (even digits). There is a spring around each key stem. Eight levers above the dials serve as decimal markers. Nine windows at the front of the machine reveal the result.
- A metal piece to the left of each “1” key is moved to prevent carrying when the complementary digits are used for subtraction. Depressing a lever on the right side of the machine allows one to turn a nearby knob and zero the number dials.
- The serial number, indicated in the front center of the machine under the decimal markers, is 1876. A second mark, on a metal tag screwed to the machine in back of the keyboard, reads: TRADE COMPTOMETER MARK (/) PAT’D (/) JUL.19.87 JUN. 11. 89. (/) OCT.11.87 NOV.25.90 (/) JAN.8.89 DEC.15.91. (/) Felt & Tarrant Mfg. Co. (/) CHICAGO.
- This machine was transferred to the Smithsonian from the U.S. Geological Survey in 1908.
- 1991.3107.06 (Catalog of the Felt & Tarrant collection).
- Currently not on view
- date made
- Felt & Tarrant Manufacturing Company
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- maker number
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- Data Source
- National Museum of American History, Kenneth E. Behring Center