Comptometer is Patented

Comptometer is Patented

On this day in 1887, Dorr Eugene Felt of Chicago, Illinois, was granted a patent for an adding machine, which he called the Comptometer. It was the first practical, key-controlled calculator with sufficient speed, reliability, and economic potential to be awarded a patent. The Comptometer was an important invention in the history of the calculator and the history of the computer, and it was also an invention that made Mr. Felt into a very wealthy man.

Felt was an American inventor and industrialist. He was born in Beloit, Rock County, Wisconsin, in 1862—the eldest of Eugene Kincaid and Elizabeth Felt’s twelve children. At the age of 15, Dorr left his local school and started working in a machine shop, and this is where his interest and skill in mechanics began. A few years later, with only 50 cents in his pocket, he left Beloit for the nearest big city—Chicago. There he started working with the Pullman Company on a maintenance crew; and then as a travelling sewing machine salesman; and then as a machinist at Ostrander and Huke’s shop, where he cut metal to varying depths on planing machines. Indeed, some of the mechanisms used in these planing machines would soon reappear in the Comptometer.

Throughout his career, Felt was always interested in inventions, and always at work on the development of ideas, including an elevator as well as all sorts of calculating machines. He was only in his early 20s when, in 1884, he came up with the idea of the Comptometer. Because of his limited resources and scarce funds, he recycled a macaroni box for the outside casing, and used staples, skewers and rubber bands for the mechanism insides. This original macaroni box prototype is now a part of the Smithsonian Museum’s collection of old calculators in Washington, DC.

Afterwards, Dorr Eugene Felt went on to invent an advanced and improved variation, called the Comptograph, which was the world’s first printing adding machine. In 1889, he founded the Felt & Tarrant Manufacturing Company with Chicago businessman Robert Tarrant, and this continued to play an important part in the calculator industry until the 1970s. Furthermore, Felt also served as an ambassador for the US Department of Commerce, which was formed after World War I, to study labour in foreign countries.

Dorr Eugene Felt died in 1930 of a stroke at the age of 68, leaving behind his wife Agnes, four daughters, and the legacy of his inventions.

Caption: A diagram of the comptometer, from US Patent 371,496.