The wrong theory was endorsed by Ptolemy, the greatest astronomer of Alexandria, and the only geographer whose work was familiar to Europeans in the late Middle Ages. In 150 A. D., Ptolemy collected all the geographical reports ever written and summed them up in one massive work. He devised the five zones which are now the tropics, the temperate and the arctic zones. For his prime meridian he adopted the Fortunate Islands to the west of both Europe and Africa. He had plenty of source material. Aside from scientific works and memoirs of adventurers, he had Roman strip maps at his disposal. All sorts of travelers' knickknacks had been devised, maps which unrolled at both ends so that the particular locality could be studied without undoing the whole map (a suggestion which modern makers of road maps might do well to imitate); and there were even silver traveling cups, made in the shape of milestones and adorned with a list of stations on the route between Cádiz and Rome.
All this mass of data was compiled by Ptolemy; but its correlation was--to say the least--difficult, and the quality of his map varied considerably. Britain is fairly well represented, but a minute island, isolated in the north and labelled "Scandia," seems to be all that he knew of the great northern peninsula. He had trouble with his scale too. There are sixty geographical miles to a degree, and he took fifty, a mistake which resulted in a general distortion. In spite of this, Ptolemy must be ranked as the greatest of early geographers; and by his time the ancient science of geography had reached its height.
Then, when the men of Alexandria and Rome felt that they had certain knowledge of just where in the world they stood, there came again that disconcerting rumor of another civilization almost half the world away--a civilization which was fit to rival the glory of Rome. The rumor was more insistent this time, so insistent that Ptolemy was forced to make some recognition of it on his map. You can discount travelers' tales, but it is harder to discount the travelers themselves, particularly when they bring their outlandish apparel into the heart of Rome's capital, and show their yellow faces even to the matter-of-fact merchants of the forum.
Via India they had come, ambassadors and envoys, bringing presents from the Emperor of China to Augustus, the Emperor of Rome. The armilla came with them for astronomers; the abacus came; and most important of all, silk was introduced into the western world. There can be no doubt of how eagerly the new cloth was accepted; the armilla and the abacus were interesting additions to science and mathematics--but for the sake of silk the trade routes must be kept open. Pliny and others might rave as they liked about the value of home products and the vanities of women who wanted the ends of the Earth combed for gauze dresses. To such pedagogues the women paid no attention. The silk had to be brought.
Under such circumstances all might have gone well and the trade routes opened once and for all; but as usual trade barriers arose. The Chinese said that the Persians were inferior weavers, but wanted the profits of trade. However that may be, the people of Asia Minor certainly did their best to hinder commerce, and ended, of course, by defeating their own aims. For one brief moment the two great nations faced each other across the intervening continent and held out their arms in friendly gesture. Then the Romans grew tired of paying duty, imported silkworms rather than silk, and the eagerness died.
For centuries afterward the Chinese continued their efforts undaunted; but at best they went only to Antioch or Constantinople, never to Rome; and the few embassies which reached China from the western world certainly traveled without official sanction. The ways of traveling were too hazardous.
In Chios the wonder-working worms were imported and put to feed on the native trees. The women of Rome had their silk so they were satisfied, and China became again a vague rumor, only half-believed by Roman ears.
Ptolemy, like all educated Greeks after Aristotle, had believed that the Earth was a globe; but in 320 A. D., a monk named Lacantius began denouncing all such ideas as heretical, and he literally knocked the spherical theory flat. There was no scientist left to resurrect it, and flat it remained until Roger Bacon a thousand years later puffed it up again with the newly found arguments of Aristotle.
The over-practical minds of the late Roman Empire had done their worst. If science led to no practical or comfortable gains they thought it valueless. In such an atmosphere pure science can never flourish. It had died before Rome fell, and the Dark Ages which showed the result were made to bear the blame for Roman negligence. Without astronomy geography is helpless. Only an astronomer can reckon latitudes or longitudes, gauge zones or even precise directions upon the Earth.
Yet the Middle Ages were not entirely barren of exploration. Trade continued, and the missionaries traveled; but for the most part they went in search of ecclesiastical rather than terrestrial knowledge. In 742 A. D., some missionaries from Constantinople reached China where they were described as "priests of great virtue." The Christian inscription says that they came by "observing stars and the Sun."
To the north, Christianity reached Scandinavia about the middle of the tenth century, and the king was so fired with religion that he sent the young son of Eric the Red to convert the colonies which Eric had founded in Greenland. Young Leif Ericson accordingly sailed toward his father's home, but bad weather drove him far off his course, and instead of landing in Greenland he found himself on the coast of an unknown country where "self-sown" wheat grew in abundance and the grapes for wine were plentiful.
Leif Ericson was sufficiently scientific to take back with him samples of wheat, of maple wood and of the wonderful grapes; so he sailed back to Greenland with his trophies and his stories of North America, which he named (with what sounds like unconscious irony to modern ears) "Wineland the Good." The discoveries created great excitement in Greenland and even in Scandinavia. A second expedition set forth, and four years later a third which consisted of one hundred and eighty men and women who intended to start a colony. Leif's father had named his island "Greenland" to attract colonizers; and the son seems to have followed in the father's footsteps. The new colony found the reports of self-growing wheat much overrated; the Indians had come and after three years' trial the Norse colony was too discouraged to stay longer.
What happened we do not know. The Norse colony returned home safely to Greenland but somehow, someone was lost and remained wandering about the new world. Perhaps the Gaels, so "incredibly fleet of foot," who were sent scouting on the second expedition, lost their way. Tablets, bearing tragic tales of Norse wanderings, have been found in Minnesota, and even recently in Colorado; but whether the scouts penetrated so far, or whether the Indians carried the stones about with them as souvenirs, it is hard to say.