He installed a transit telescope at the Royal Observatory at Greenwich,
England, and accurately measured Greenwich Mean Time by the stars as
they crossed the meridian.
Airy became the seventh Astronomer Royal 1835. He began the distribution
of Greenwich time signals by telegraph, and Greenwich Mean Time as measured
by Airy's telescope was adopted as legal time in Britain 1880.
Airy was born in Alnwick, Northumberland, and studied mathematics at
Cambridge, where he became professor of mathematics 1826 and of astronomy
1828. As director of the Cambridge Observatory, he introduced a much
improved system of meridian observations and set the example of reducing
them in scale before publishing them.
As Astronomer Royal, in 1847 he had erected the alt-azimuth (an instrument
he devised to calculate altitude and azimuth) for observing the Moon
in every part of the sky. Other innovations included photographic registration
in 1848, transits timed by electricity in 1854, spectroscopic observations
from 1868, and a daily round of sunspots using the Kew heliograph in
Airy's mathematical skills were used in establishing the border between
Canada and the USA and the boundaries of the states of Oregon and Maine.
His scientific expertise was also called on during the launch of the
steamship Great Eastern, the laying of the transatlantic telegraph cable,
and the construction of the chimes of the clock in the tower of the
Houses of Parliament ('Big Ben'). His Mathematical Tracts on Physical
Astronomy 1826 became a standard work.