George Biddell Airy, English geophysicist and astronomer, c 1860s.

UNITED KINGDOM - SEPTEMBER 09: Photograph by Maull & Polyblank of Sir George Biddell Airy (1801-1892), who was Astronomer Royal and director of the Royal Greenwich Observatory from 1835 to 1881. Airy initiated the efficient and accurate observation of stellar positions, published works on celestial mechanics and made discoveries in theoretical and practical optics. He reorganised the Greenwich Observatory and discovered errors in planetary theory in relation to the motion of the Earth and Venus. A telescope designed by Airy was used to measure Greenwich Mean Time, which became Britain's legal time in 1880. (Photo by SSPL/Getty Images)