Ramsden's dividing engine, 1773.
© Science Museum / Science & Society Picture Library
Engraving of the dividing engine designed by instrument-maker Jese Ramsden (1735-1800). Dividing engines are used to delineate the linear and circular scales of measuring instruments used in astronomy and navigation, as well as in other sciences. Illustration from Ramsden's 'Description of an Engine for dividing mathematical instruments', published in London in 1777.