Designed by Charles Thomas de Colmar, the Arithmometer was the first calculating machine considered ‘successful’ in terms of sales figures. Records show that the Arithmometer was first released in c1820 however production didn’t increase until 1844 with the release of a new design with a wooden shell and light weight pieces. During its time many new designs and features were added including a zeroing lever, smaller design and altered crank handle position in 1850, multiplicative counter for repeated additions in 1852 ending with a final design in 1860 with a quotient dial and zeroing mechanism for it.
The arithmometer can add, subtract, divide and multiply but was not the first machine to do this. What made this machine special was its lightweight body and parts and functionality. The machine made use of Leibniz step cylinders which were adjusted in height by button number. Each cylinder would then on a turn of the crank handle engage and rotate the number of steps on the cylinder. By doing this one crank the user could add an entire number as set on the lower viewing panel and multiplication could be achieved through repeated additions. The arithmometer was also the first machine to boast of a moveable upper carriage. This meant that multiplication could be made much quicker as with additions and subtractions and larger numbers could be quickly entered into the machine. In order to achieve addition and subtraction the user would select using a switch whether the crank arm would engage the previously discussed step cylinders to add or reverse rotation and subtract.
Common areas of use for this device were in government and financial agencies such as banks and insurance companies, observatories and education as it was the first reliable and multifaceted mathematical tool of its time. This one was one of many used by surveyors in Queensland Lands Department
Charles de Colmar’s Arithmometer was the first of many early calculators of the century to come and paved the way for more compact mechanical designs such as the Curta and Contex calculators.
This item is part of the UQ Physics Museum Good Old days of Calculation Tour
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