Clarence Jennings, age 10, of Some set, New Jersey, for his question:
Who was Ptolemy?
The name Ptolemy has come down through the ages with a ring of grandeur. Actually it belonged to several grand kings and queens and to one special person who made a very grand contribution to the world of science. All these Ptolemies lived within a few centuries before and after the beginning of the Christian Era.
The first Ptoleray rose to fame as a general and bodyguard of Alexander the Great. When Alexander died in 323 B.C. this Ptolemy :seized the throne of Egypt and his descen¬dants ruled there for almost 300 years. One of the later members of this Ptolemy family of pharoahs was the famous Cleopatra and the dynasty ended with her son. We do not knew whether these grand Ptolemies were kinfolk of the famous Ptolemy who contributed so much to science in the ancient world. History gives us very little information about his personal life. Scanty records suggest that he was born in a Greek City, probably early in the second century A.D. Iris original name was Claufus Ptolemaus.
We do know that from 127 A.D. this Ptolemy lived as a scholar in the Egyptian city of Alexandria. He continued is work there until A.D. 145 and possibly to A.D. 151. During this time he did an immense amount of original work in math and music, in optics, geography and astronomy. Ptolemy was regarded as the greatest scholar of his day and through the next 14 centuries hardly anyone questioned his ideas.
Ptolemy's greatest talent was the writing of facts in understandable form so that students could grasp them, step by reasonable step. Many of his basic ideas were borrowed from earlier scholars, but he stated them more clearly and his logical mind ad¬vanced them into entirely new dimensions. Many Creek scholars reasoned that the world is round and that circles of latitude could be used to measure it. Ptolemy believed in a round world and used the basic circles to map the known and unknown regions of the entire globe.
Ptolemy must have known that the language of science is math. In 13 volumes titled, "The Mathematical Collection," he noted down the precise steps he used in astro¬nomy and geography, including the trigonometry used by surveyors and the great circles still used to chart the earth and the heavens. Arab students later called this work the "Algamest," meaning "the greatest." Ptolemy also used his math systems to study music and reported his findings in three volumes titled "Harmonica." He also wrote five volumes called "Optics" about the refraction of light beams through various substances. These works, together with his immense writings on astronomy and geography, were major textbooks for 1,400 years.
Ptolemy has the respect and gratitude of modern science. But even the greatest thinkers make errors. Ptolemy was sure that his round earth was the center of the Universe and that all the heavenly bodies revolved around it. This idea was not chal¬lenged until about 400 years ago. His global map overestimated the land masses and underestimated the size of the oceans. Columbus consulted Ptolemy's maps, and in 1492 this 1400 year old error in land and sea led to some problems in his great venture of discovery.