Bharatiya Jyotihshastra (History of Indian Astronomy), translated by R. V. Vaidya v2.c12.s5.48.2

v2.c12.s5.48.2

The date of this solstice has been chosen for the epoch of the Metonic cycle of nineteen years.* A new era commenced in the history of astronomical observation when *Alexandria* became the capital of the civilized world. Under the liberal patronage of the Ptolemies a magnificent building was erected, in which were deposited circular instruments for determining the positions of the heavenly bodies, and every facility was given to astronomers for prosecuting a continuous series of observations. Timocharis and Aristillus are the earliest individuals mentioned in connexion with this school. These astronomers appear to have flourished about the year 300 A.C. Ptolemy (150 A.D.) cites several of their observations. Among these are the declinations of a few of the principal stars and the records of eclipses. It does not appear that they were acquainted with any method for determining the right ascensions of the stars. Eratosthenes (275 B.C. circa) one of the Alexandrian astronomers, determined the obliquity of the ecliptic to be 23° 51' 19". It is manifest that neither the distances of the stars from the equator nor the obliquity of the ecliptic could have been determined even roughly without the use of instruments. In treating of the obliquity of the ecliptic, Ptolemy describes an instrument for determining the meridional altitude of the sun.