Fig. 3. Ptolemy World Map.
Map making and the science of geography were continuously progressive among the Greeks. Imperial Rome witnessed little progress in either field. Among those who wrote in the Latin language, Pomponius Mela (fl. ca. 43 A. D.)[16] and Pliny (ca. 23-79 A. D.)[17] alone have rank of importance. In the matter of map construction the Romans held to many of the cruder methods and ideas of the Greeks, a fact which we learn from the fragmentary references in their literature, and from the itinerary or road maps (Fig. [4]), of the period of the emperors, which have come down to us.[18]
Fig. 4. Sections of Peutinger Tables.
The idea of a globular earth was at first accepted by the geographers of antiquity with some hesitancy. That Thales (640-548 B. C.),[19] one of the earliest astronomers and cosmographers, openly supported this theory, as is sometimes asserted, is hardly probable. It is rather to be assumed that according to his idea the earth has the form of a cylinder, and that it moves within a hollow sphere, an idea upheld by Anaximander, his disciple and successor, to whom reference has been made above. It was the Pythagorean philosophers who appear to have first transferred to the earth that which had already been accepted as a theory relative to the heavens, including the imaginary circles and the circular or spherical form, apparently arguing that the earth is a sphere because that is the most perfect form, that it is located in the center of the universe because that is the place of honor, and that it is at rest because rest is more dignified than motion.[20] It however was Aristotle who undertook, in the manner of a philosopher, an elaborate defense of the Pythagorean doctrine of a globular earth, supporting his arguments, first, through a reference to such positive proof as may be found in gravitation or “the tendency of all particles of matter to form themselves about the middle and thus make a sphere,” and secondly, through a reference to the appearance of the earth’s shadow cast during an eclipse of the moon.[21] A third proof, so familiar to us today, that distant objects as we approach them gradually reveal themselves above the horizon, seems not to have occurred to Aristotle, but was first employed by Strabo. “It is evident,” says the latter, “that, when persons on shipboard are unable to see at a distance lights which are on a level with the eye, the cause of this is the curvature of the sea; for if those lights are raised to a higher level, they become visible, even though the distance is increased; and in like manner, if the beholder attains a greater elevation he sees what was previously hidden.... Again, when men are approaching the land from the sea, the parts nearest the shore-line come more and more into view, and objects which at first appeared low attain a greater elevation.”[22]
After the attempt had been made to determine the circumference of the earth, as was done by Eratosthenes with more or less satisfactory results, the thought, very naturally, was suggested of making an artificial representation of the entire earth, so far as then understood, that is, of making a terrestrial globe. There is no intimation, however, in any early allusion to Eratosthenes that he was a globe maker, or that he knew anything about globe construction. We know that he thought of the earth as a sphere placed in the center of the universe, around which the celestial sphere revolves every twenty-four hours.[23] Strabo, at a much later date, in referring to the geographical ideas of Eratosthenes, censured him for his unnecessarily elaborate proofs of the earth’s spherical character, apparently thinking the fact one too well known to require demonstration.
