CHRISTIE, SIR WILLIAM HENRY MAHONEY (1845-1922), British astronomer, son of Samuel Hunter Christie, professor of Mathematics at the royal military academy, Wool wich, was born at Woolwich on Oct. 1, 1845. He was educated at King's College school, London, and at Cambridge. In 187o Christie was appointed chief assistant to Airy at the royal observatory, Greenwich, and in 1881 astronomer royal; he retired from this post at the age of sixty-five.
While Christie was at the observatory the work was consider ably extended, and it was largely due to him that regular spectro scopic and photographic observations were started. Some of these photographs form a valuable part of the work of the observatory and the observations are still continued. Between 1890 and 1898 Christie supervised the construction of a new building and the erection of a 3o inch reflector and a 26 inch photographic refractor, enabling the observatory to take part in the international photo graphic map of the heavens; the measurements and publication of results occupied a number of years. Christie erected a wooden building for magnetic observations, designed a new altazimuth to replace a faulty one which had been used by Airy and also designed a "duplex" micrometer for identifying stars on over lapping plates.
Christie is the author of a number of papers embodying his work on the solar eclipses observed in Japan (1896), India (1898), and Portugal (1900), on the measurement of double stars, on the observations of Eros for determining the solar parallax and on the duration of exposure in photographing stars.
Christie was a member of many learned societies at home and abroad; he received the C.B. on the occasion of Queen Victoria's Jubilee and the K.C.B. in 1904. He died on Jan. 22, 1922 while on a voyage to Mogador and was buried at sea.