John Frederic Daniell, English metrologist and chemist, c 1830s.
© Science Museum / Science & Society Picture Library
John Frederic Daniell (1791-1845) was a profesor of chmesitry at Kings College, London from 1831. He invented the Daniell electric cell in 1836, a pyrometer in 1830 and a hygrometer in 1820. Daniell also wrote an 'Introduction to Chemical Philosophy', published in 1839.