He was the first to describe a location on the planet
according to its longitude and latitude, and the first to
introduce that a CIRCLEis divisible into 360°. He calculated
the solar year to measure 365^1 / 4 days, minus 4 minutes, 48
seconds, which is off by just six minutes, and the lunar year
to be 29 days, 12 hours, 44 minutes, 2^1 / 2 seconds, which is
off by less than one second. His only surviving work is a
three-volume book entitled Commentary on Aratus and
Eudoxus.PTOLEMY’s work is believed to be based largely on
Hipparchus’s, and many believe that the Ptolemaic Theory
should really be named the Hipparchian Theory.Holywood, John de (Johannes De Sacrobosco, John of
Hollywood, John of Halifax)(ca. 1200–56) This medieval
English mathematician and astronomer wrote several books
that became texts, including Tractatus algorismion arithmetic,
Tractatus de Spheraon astronomy, which was used for four
centuries, Tractatus de Quadranteon quadrants, and De Anni
Rationeon time and the calendar.Hypatia of Alexandria(ca. 370–415) Egyptian astronomer,
philosopher, teacher, and mathematician regarded as the first
woman scientist, and the first woman to contribute to the study
of mathematics. As head of the Platonist school in Alexandria,
in addition to teaching through lectures, she wrote about the
work of others, including DIOPHANTUS’sArithmetica,
Apollonius and PTOLEMY’s work, and with her father on
EUCLID’sElements.Her mathematical abilities were
exceptionally helpful in her work on astronomy, particularly in
her construction of an astrolabe to measure the positions of
heavenly bodies. Since science was, at her time, related to
paganism by the Christians then coming into power, Hypatia
was declared an evil enemy of the church, and was
subsequently attacked and murdered by a mob, which many
historians believe marked the beginning of the end of
Alexandria’s reign as a major center of scientific learning.Ibn Ezra, Abraham ben Meir (Rabbi Ben Ezra, Aben Ezra)
(1092–1167) This Jewish scholar lived in Spain and traveled
extensively. He was known as a great poet, but his scientific
interests led to writing about mathematics, particularly The
Book of the Unitand the Book of the Number.Both writingsBIOGRAPHIES Holywood – Ibn Ezra
BIOGRAPHIES Holywood – Ibn Ezra