GREENWICH OBSERVATORY, the most important public observatory in England, located at Greenwich (q.v.) on the prime meridian in lat. + 51° 28' 38.4" N. It was estab lished by King Charles II in 1675, for the pur pose of promoting navigation and astronomy. The direction of the observatory is under the charge of the Astronomer-Royal, who is as sisted by eight astronomers and a staff of computers. The chief instruments employed are a meridian circle, having a circle six feet in diameter and an eight-inch telescope: and an eight-inch altazimuth, both by Sims; Lassell's two foot reflector; and Grubb's 28-inch re fractor, 13-inch, 26-inch and 9-inch photo graphic refractors; the last two having been presented by Sir H. Thompson. The standard motor clock is also located here, which, by electrical connection,• controls a system of clocks throughout the United Kingdom. The deoartrnent of magnetics and meteorology was established in 1838, since when valuable ob servations have been made in this field.
Since 1750, all observations made have been strictly recorded, the annual publications be ginning in 1836. Separate volumes are de voted to Star Catalogues and he Reductions of Lunar and Planet Observations. The principal efforts of the observatory have been devoted to determining the positions of the stars, planets and sun, the accurate following of the course of the moon and the daily recording of sun spots.
The first Astronomer-Royal was John Flamsteed (1675-1719). He was followed by Edmund Halley (1720-42). Under James Bradley (1742-62) the science of modern stellar astronomy was established. George Airy (1835-81) brought the work of the ob servatory to its present state of efficiency.