The incident which Herodotus does not believe, but puts in anyway, proves the point. The ship, sailing from east to west along the coast of Africa, had reached the Southern Hemisphere.
There had been other voyages of a purely exploratory nature about the same time. One expedition was sent by Darius the Great to the Indus for just the same reason that the 'Satiable Elephant's child traveled to the Limpopo--to find out what the crocodile had for breakfast--and as early as 1500 B. C., the first Queen of Egypt dispatched five ships up the Red Sea in search of tropical luxuries.
So by the time of Herodotus men had circumnavigated Africa, penetrated into Asia and heard rumors of the Arctic. The northeast they knew was populated by great hordes of nomad people, Scythians, who served as the buffoons and country yokels in comic Greek plays, and were unconquerable because they simply hitched their wagons to oxen and wandered off whenever a foe appeared. This disconcerting habit has left us without definite knowledge of who the Scythians were or where they went. It is true that they ate haggis, but the modern notion that they wore kilts, played the bagpipes, and spoke a language resembling Gaelic, seems to have no foundation in fact.
Beyond them there were desert and mountains inhabited by strange peoples--for it was from this region that the weirdest legends grew; but there was a story, passed by word of mouth along the vast stretches of Asia, that in the east, farther than any man had thought to go, there lived the "gold-bearing griffons"-the inhabitants of China. That was a story brought back by a poet named Aristeas, "but," said Herodotus, "even he did not claim to have gone further than the last of the Scythians--and he was writing poetry." That story seems to have been forgotten by the time of Alexander the Great. Perhaps Aristotle, who was Alexander's tutor, distrusted anthropologists and poets alike; if so, it seems a pity; for if only Aristotle had not entertained such a passion for accuracy, Alexander would have known that there were more worlds to conquer.
In spite of his distrust of Herodotus, Aristotle was an active geographer. He fully believed that the Earth was spherical and gave three proofs to establish his claim. First, it must be spherical because bodies tend to congregate at their common center (if he had carried this argument to its logical conclusion, he might have anticipated Newton); second, because the shadow of the Earth during eclipses of the Moon was always circular, and no body other than a sphere could throw a circular shadow at all times; and last, because no other explanation would account for the shifting range of constellations which came above the horizon as one traveled from north to south. Rate of travel was always used to measure distance, and there was no reason why it should not do well enough for a rough measurement. Pacing is still used today for topographic reconnaissances and a trained surveyor is able to measure distance by pacing, to an accuracy approaching one per cent of the distance traveled. No one who has ever read Xenophon can possibly forget his reiterated account:
'Εντευ+̑ηεν ὲΞελαύνει σταημοὺς δύο, παρασὰγγας δέκα.
"From there we marched two days travel, ten parasangs." Maps made in the eighteenth century A. D. still showed the scale of distance in "hour's journey" in addition to English, Scottish, Irish and German miles. It was a slightly dubious measurement in the old days, particularly with people like Herodotus who could not possibly add straight; but in the army of Alexander the Great there were trained "bematists" whose particular business it was to measure by pacing the distance traversed. The data acquired by these men was used by Dicaearchus of Messana, a pupil of Aristode's, to write a topography of Greece and make maps of the world.
Directions had always been given by some vaguely relative system. A place was so many days journey north of Alexandria, or south of Crete, but by the fourth century B. C., geographers began to feel the need of some more definite system. Someone had the brilliant inspiration that lines could be drawn between the places having equally long days on the summer solstice, rather as we draw contour lines between places of equal altitude--only in this case the lines would not jiggle all over the place, but would form a straight line across the section of the map. Thus were latitudes invented, and Dicaearchus of Messana seems to have been the first to use them. He was not quite correct, for his parallel of the Mediterranean was extended along the Taurus mountains in Asia Minor, and even through the Himalayas, but the idea of latitude was a great step forward in scientific geography.