The other great geographer, Claudius Ptolemy, belongs to a later period (A.D. 100) but it is convenient to notice him here. Possibly he was a connection of the late royal family, but nothing is known of his life. His fame has outshone Eratosthenes’, and no doubt he was more learned, for more facts were at his disposal. Yet we can trace in him the decline of the scientific spirit. Observe his Map of the World (p. [39]). At first sight it is superior to the Eratosthenes Map. The Caspian Sea is corrected, new countries—e.g. China—are inserted, and there are (in the original) many more names. But there is one significant mistake. He has prolonged Africa into an imaginary continent and joined it up to China. It was a mere flight of his fancy: he even scattered this continent with towns and rivers. No one corrected the mistake and for hundreds of years it was believed that the Indian Ocean was land bound. The age of enquiry was over, and the age of authority had begun, and it is worth noting that the decline of science at Alexandria exactly coincides with the rise of Christianity.
(iii). Astronomy and the Calendar.
Astronomy develops on the same lines as Geography. There is an early period of scientific research under Eratosthenes, and there is a later period in which Claudius Ptolemy codifies the results and dictates his opinions to posterity. He announced, for example, that the Universe revolves round the Earth, and this “Ptolemaic” Theory was adopted by all subsequent astronomers until Galileo, and supported by all the thunders of the Church. Yet another view had been put forward, though Ptolemy ignores it. Aristarchus of Samos, working at Alexandria with Eratosthenes, had suggested that the earth might revolve round the sun, and it is only a chance that this view was not stamped as official and imposed as orthodox all through the Middle Ages. We do not know what Aristarchus’ arguments were, for his writings have perished, but we may be sure that, working in the 3rd century B.C., he had arguments and did not take refuge in authority. Astronomy under the Ptolemies was a serious affair—lightened only by the episode of Berenice’s Hair.
As to the Calendar. The Calendar we now use was worked out in Alexandria. The Ancient Egyptians had calculated the year at 365 days. It is actually 365 ¼, so before long they were hopelessly out; the official Harvest Festival, for instance, only coincided with the actual harvest once in 1,500 years. They were aware of the discrepancy, but were too conservative to alter it: that was left to Alexandria. In B.C. 239 the little daughter of Ptolemy Euergetes died, and the priests of Serapis at Canopus passed a decree making her a goddess. A reformer even in his grief, the King induced them to rectify the Calendar at the same time by decreeing the existence of a Leap Year, to occur every four years, as at present; he attempted to harmonise the traditions of Egypt with the science of Greece. The attempt—so typical of Alexandria—failed, for though the priests passed the decree they kept to their old chronology. It was not until Julius Caesar came to Egypt that the cause of reform prevailed. He established the “Alexandrian Year” as official, and modelled on it the “Julian,” which we use in Europe to-day; the two years were of the same length, but the “Alexandrian” retained the old Egyptian arrangement of twelve equal months.
(iv). Medicine.
Erasistratus (3rd. cent. B.C.) is the chief glory of the Alexandrian medical school. In his earlier life he had been a great practitioner, and had realised the connection between sexual troubles and nervous breakdowns. In his old age he settled in the Mouseion, and devoted himself to research. He practised vivisection on animals, and possibly on criminals, and he seems to have come near to discovering the circulation of the blood. Less severely scientific were the healing cults that sprang up in the great temples of Serapis, both at Alexandria and at Canopus;—cults that were continued into Christian times under other auspices.
Site of Mouseion: p. [105].
Map of Eratosthenes: p. [37].
Map of Claudius Ptolemy: p. [39].
Temple of Serapis at Canopus: p. [180].