Loose pebbles were the first objects used to aid humans in calculating numbers. Later they were used as counters on ruled boards before a range of materials were used to suspend counters on wire frames. This fixed wire structure known as the 'abacus' was developed in India and later adopted in China and Europe.

In 1614 John Napier invented a system of logarithms that simplified some of the more complex calculations needed for navigation. This table of 'logs' was converted into a series of engraved numerals on wooden rods which were arranged and read in a specially made box. Known as 'Napier's Bones' this device was improved on by Edmund Gunter who simplified Napier's logarithms making his 'bones' an essential tool for navigators throughout the seventeenth and eighteenth centuries.

In the late 1600s there were a series of important steps in the development of the calculating machine. From 1663 to 1666, Sir Samuel Morland invented three calculating machines which set the standard for design and construction. In 1668 Gaspard Schott's designed a machine arranged on rotatable cylinder and fixed in a box which would perform Napier's calculations. In 1694 Leibniz constructed a multiplying machine that performed repeated additions using a device known as a 'stepped reckoner' and this device was included in many subsequent adding machines.

The first successful manufacture of a commercial calculating machine did not occur until 1820 when Charles Thomas developed a model which would form the basis for machines up until the 1920s. Over the eighteenth century, attempts to make a satisfactory calculating machine had been hindered by a lack tools capable of precisely engineering details such as the wheel teeth. In the 1830s, Cartier and Whitworth introduced gear-cutting machines which did away with the need to make teeth manually using chisels and files.

By Geoff Barker, April 2008

References
Baxandall, D., 'Calculators Machines and Instruments, Science Museum, 1975
Wynter, H., and Turner, A., 'Scientific Instruments', Studio Vista,1975
Kidwell, P., and Ceruzzi, P., 'Landmarks in Digital Computing; a Simthsonian Pictorial History', Smithsonian Institution Press, United States of America,1994
Williams, M., 'A History of Computing Technology', Whitehall Books, Wellington, New Zealand, 1985
Daumas, M., 'A History of Technology and Invention; Progress Through the Ages, Vol 3, Crown, New York, United States of America, 1979

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