Comptometers

A Comptometer was a type of mechanical calculator that performed addition, subtraction, multiplication, and division. Invented by Robert T. Parish in 1888 and later patented by John Stephanus in 1902, it was one of the earliest and most successful mechanical adding machines. Comptometers used a system of keys and wheels to perform calculations. Unlike later calculators, the Comptometer was operated by striking keys, which directly actuated the calculating mechanism. Each column of keys represented a decimal place, and pressing a key would add a specific value to that place.

The machine was notable for its speed and accuracy for its time. Early models were large and heavy, but later versions became more compact. Comptometers were widely used in businesses and offices from the early 20th century until the advent of electronic calculators in the 1970s. They were particularly useful for tasks requiring extensive arithmetic, such as accounting, payroll, and statistical work. The distinct sound of a Comptometer in operation became a familiar part of many business environments. The company that produced them, Felt & Tarrant Manufacturing Company, was a significant player in the office equipment industry for decades. While largely superseded by electronic devices, the Comptometer represents an important step in the history of computing and automation.