Hipparch us

, a son of Pis i stratus, who succeeded his father as tyrant of Athens, with his brother Hippias. He patronized some of the learned men of the age, and distinguished himself by his fondne for literature. The seduction of a sister of Harmodius raised him many enemies, and he was at last a a inated by a desperate band of conspirators, with Harmodius and Aristo git on at their head, 513 years before Christ. Ælian , Varia Hist or i a , bk. 8 , ch. 2 .――One of Antony’s freedmen.――The first person who was banished by ostracism at Athens.――The father of Asclepiades.――A mathematician and astronomer of Nicæa. He first discovered that the interval between the vernal and the autumnal equinox is 186 days, seven days longer than between the autumnal and vernal, occasioned by the eccentricity of the earth’s orbit. He divided the heavens into 49 constellations, 12 in the ecliptic, 21 in the northern, and 16 in the southern hemisphere, and gave names to all the stars. He makes no mention of comets. From viewing a tree on a plain from different situations, which changed its apparent position, he was led to the discovery of the parallax of the planets, or the distance between their real or apparent position, viewed from the centre and from the surface of the earth. He determined the longitude and latitude, and fixed the first degree of longitude at the Canaries. He likewise laid the first foundations of trigonometry, so e ential to facilitate astronomical studies. He was the first who, after Thales and Sulpicius Gallus, found out the exact time of eclipses, of which he made a calculation for 600 years. After a life of labour in the service of science and astronomy, and after publishing several treatises and valuable observations on the appearance of the heavens, he died 125 years before the christian era. Pliny , bk. 2 , ch. 26 , . ――An A then i an who conspired against Heraclides, who kept Athens for Demetrius, . Polyænus , bk. 5 .