Adding Machine

An adding machine was a class of mechanical calculator, usually specialized for bookkeeping calculations. In the United States, the earliest adding machines were usually built to read in dollars and cents. Adding machines were ubiquitous office equipment until they were phased out in favor of calculators in the 1970s and by personal computers beginning in about 1985. The older adding machines were rarely seen in American office settings by the year 2000.

Blaise Pascal invented the mechanical calculator in 1642; it was an adding machine that could perform additions and subtractions directly and multiplication and divisions by repetitions. He was followed by Thomas de Colmar who launched the mechanical calculator industry in 1851 when he released his simplified arithmometer (it took him thirty years to turn his complex multiplying machine, patented in 1820, into a simpler and more reliable adding machine). However they didn't gain widespread use until Dorr E. Felt started manufacturing his comptometer (1887) and Burroughs started the commercialization of his adding machine (1892).