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1851

Thomas Arithmometer

Gottfried Wilhelm Leibniz (1646–1716), Charles Xavier Thomas de Colmar (1785–1870)

“German philosopher and mathematician Gottfried Leibniz became interested in mechanical calculation after seeing a pedometer while visiting Paris in 1672. He invented a new type of gear that could advance a 10-digit dial exactly 0 to 9 places, depending on the position of a lever, and used it in a machine with multiple dials and levers called the stepped reckoner. Designed to perform multiplication with repeated additions and division by repeated subtractions, the reckoner was hard to use because it didn’t automatically perform carry operations; that is, adding 1 to 999 did not produce 1,000 in a single operation. Worse, the machine had a design flaw—a bug—that prevented it from working properly. Leibniz built only two of them.

More than 135 years later, Charles Xavier Thomas de Colmar left his position as inspector of supply for the French army and started an insurance company. Frustrated by the need to perform manual arithmetic, Thomas designed a machine to help with math. Thomas’s arithmometer used Leibniz’s mechanism, now called a Leibniz wheel, but combined it with other gears, cogs, and sliding levers to create a machine that could reliably add and subtract numbers up to three digits, and multiply and divide as well. Thomas patented the machine, but his business partners at the insurance firm were not interested in commercializing it.

Twenty years later, Thomas once again turned his attention to the arithmometer. He demonstrated a version at the 1844 French national exhibition and entered competitions again in 1849 and 1851. By 1851, he had simplified the machine’s operation and extended its capabilities, giving it six sliders for setting numbers and 10 dials for display results. Aided by three decades’ advance in manufacturing technology, Thomas was able to mass-produce his device. By the time of his death, his company had sold more than a thousand of the machines—the first practical calculator that could be used in an office setting—and Thomas was recognized for his genius in creating it. The size of the arithmometer was approximately 7 inches (18 centimeters) wide by 6 inches (15 centimeters) tall.”

SEE ALSO Curta Calculator (1948)

“This Thomas Arithmometer can multiply two 6-digit decimal numbers to produce a 12-digit number. It can also divide.”