OBSERVATORY, a building devoted co the observation of astronomical, mag netic, meteorological, or other natural phenomena. The astronomical observa tory is the one of most general interest. Astronomical observation began at an early date in China; the pyramids in Egypt seem in some way to have been associated with stellar observation; and the first historical observatory was founded in Alexandria 300 B. c. Its work was begun by Aristillus, and continued by Timocharis, Hipparchus, Aristarchus, and others. The first European obser vatory was built at Nuremberg by Ber nard Walther in 1472, and this was fol lowed in the 16th century by Tycho Brahe's famous observatory on the island of Hveen, near Copenhagen. These were followed by the construction of the Royal Observatory at Paris (1667), the Green wich Royal Observatory (1675), the Tusculan Observatory near Copenhagen (1704), Berlin (1705; new observatory 1835), Vienna (1756), Dublin (1785), Konigsberg (1813), Sydney (1820), Cape of Good Hope (1820), Edinburgh (1825), Pulkowa near St. Petersburg (1839), Cambridge, Mass. (1839), Wash ington, D. C. (1845), Melbourne (1853),
Lick Observatory, California (1888), and the Yerkes Observatory at Lake Geneva, Wis. (1897).
Dun Echt Observatory, the private ob servatory of the Earl of Crawford, near Aberdeen, Scotland, has attracted con siderable attention as a center of dis tribution of astronomical telegraphic news, the Dun Echt circulars, in con nection with the international code telegrams, being the medium of com munication.
The chief instrument used in the ob servatory is the telescope, whether in the form of the equatorial or in the mural circle and transit instrument, to gether with the sidereal and the solar clock. In 1919 the Carnegie Institute in stalled a 100-inch reflector, largest in the world, in their Solar Observatory, Mt. Wilson, Pasadena, Cal. The observatory building must be constructed in a very stable manner, and as the instruments must be out of contact with the walls they are attached to stone pillars that rest on foundations separate from the rest of the building.