Tables from a book of logarithmic tables by Callet, 1795.
© Science Museum / Science & Society Picture Library
A table of logarithms created by Francois Callet and printed in Paris for the English market. This English edition is one of the selection of tables collected by the British mathematician and computing pioneer Charles Babbage (1791-1871). His private collection preserved at the Royal Observatory at Edinburgh contained over three hundred volumes. He was a fastidious analyst of tabular error. Mathematical tables were an aid to those profesions which required the performing of calculations demanding more than a few figures of accuracy. Logarithms made the manipulation of large calculations simpler by adding or subtracting the index of two numbers and looking up the result in tables.