MATHEMATICIAN, ASTRONOMER

Work
Hypsicles lived in Alexandria. He studied arithmetical progressions, and wrote treatises on a number of mathematical and astronomical topics:

"On polyhedrons": Extant. Contains eight interesting propositions on the relations between regular dodecahedrons and regular icosahedrons inscribed in the same sphere. This book is a continuation of Euclid's Elements, and is generally known as Book XIV of that work.

"On the harmony of the spheres": Lost.

"Polygonal numbers": Described as sums of arithmetical progressions, the ratio of which is equal to the number of sides less two of the corresponding polygonals.

"On risings": Calculates the length of each day of the year in Alexandria. The ecliptic is divided into 360?. The time of rising of each constellation in the zodiac circle at Alexandria is calculated on the basis of differential tables, after the Chaldaean manner, rather than by the trigonometric tables of Hipparchus. This treatise is extremely valuable, for it represents the link between the astronomers of Chaldaea and the Hellenistic Greeks.