George Biddell Airy, English astronomer and geophysicist, 1868.

ENGLAND - APRIL 14: Engraving from a photograph by J Watkins, taken from the �Illustrated London News�. The English astronomer and geophysicist, Sir George Bidell Airy (1801-1892) was Astronomer Royal and director of the Royal Greenwich Observatory from 1835 to 1881. He organised the accurate observation of stellar positions and advanced theoretical and practical optics. He discovered errors in planetary theory in relation to the motion of the Earth and Venus. He designed the telescope used to measure Greenwich Mean Time, Britain's official time from 1880, having previously standardised timekeeping by means of an electric master clock, which sent pulses via telegraphy. (Photo by SSPL/Getty Images)