John Wallis, English mathematician, 1670.
© Science Museum / Science & Society Picture Library
Engraving by R Cooper made in 1825 after a drawing by Derby, taken from an original painting by G Kneller showing a portrait of John Wallis (1616-1703). Wallis became famous for his contributions to algebra and analytical geometry. Wallis worked to decipher intercepted letters for the Parliamentarians in the English Civil War, and was also was succesful with teaching deaf- mutes to speak.