page_title: Comptometer
section_title: Comptometer and comptograph
hierarchical_section_title: Comptometer / History / Comptometer and comptograph
context_page_description: The comptometer was the first commercially successful key-driven mechanical calculator, patented in the United States by Dorr E. Felt in 1887.
  A key-driven calculator is extremely fast because each key adds or subtracts its value to the accumulator as soon as it is pressed and a skilled operator can enter all of the digits of a number simultaneously, using as many fingers as required, making them sometimes faster to use than electronic calculators. Consequently, in specialized applications, comptometers remained in use in limited numbers into the early 1990s, but with the exception of museum pieces, they have all now been superseded by electronic calculators and computers.
  Manufactured without interruption from 1887 to the mid-1970s, it was constantly improved. The mechanical versions were made faster and more reliable, then a line of electro-mechanical models was added in the 1930s. It was the first mechanical calculator to receive an all-electronic calculator engine in 1961, with the ANITA Mark VII model released by Sumlock Comptometer. This created the link between the mechanical calculator industries and the electronic.
context_section_description: The original comptometer design was patented by Felt, on July 19, 1887 and on October 11, 1887.
  Two years later, on June 11, 1889, he was granted a patent for the Comptograph.  A Comptograph is a comptometer with a printing mechanism making it more like a key-set calculating machine (even though the keys are registered as they are typed and not when a handle is pulled), therefore slower and more complicated to operate. It was the first printing-adding machine design to use individualized type impression which made its printed output very legible.
  The first comptograph was sold to the Merchants & Manufacturers National Bank of Pittsburgh, PA. in December 1889. It was the first sale of a recording-adding machine ever. This machine is now on display at the Smithsonian Institution in Washington, D.C..
  The Felt & Tarrant Manufacturing Company built both comptometers and comptographs throughout the 1890s. In 1902, the Comptograph Company was set up to manufacture comptographs exclusively, but was shut down at the beginning of World War I.
  Forty years later, in the mid-1950s, the Comptometer Corporation reused the name Comptograph for a line of 10 key printing machines.
caption: Comptograph (1914)
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