Therefore it was before the age of Columbus that, east and west along the temperate belt, men's minds groped to find new conditions beyond the range of known habitable regions. Strabo, in the first century before Christ, made this habitable zone stretch over 120 degrees, or a third of the circumference of the earth. The corresponding extension of Marinus of Tyre in the second century after Christ stretched over 225 degrees. This geographer did not define the land's border on the ocean at the east, but it was not unusual with the cosmographers who followed him to carry the farthest limits of Asia to what is actually the meridian of the Sandwich Islands. On the west Marinus pushed the Fortunate Islands (Canaries) two degrees and a half beyond Cape Finisterre, failing to comprehend their real position, which for the westernmost, Ferro, is something like nine degrees beyond the farther limits of the main land.
Ptolemy's view.
The belt of the known world running in the direction of the equator was, in the conception of Ptolemy, the contemporary of Marinus, about seventy-nine degrees wide, sixteen of these being south of the equatorial line. This was a contraction from the previous estimate of Marinus, who had made it over eighty-seven degrees.
Toscanelli's view.
Toscanelli reduced the globe to a circumference of about 18,000 miles, losing about 6,000 miles; and the untracked ocean, lying west of Lisbon, was about one third of this distance. In other words, the known world occupied about 240 of the 360 degrees constituting the equatorial length. Few of the various computations of this time gave such scant dimensions to the unknown proportion of the line. The Laon globe, which was made ten or twelve years later than Toscanelli's time, was equally scant. Behaim, who figured out the relations of the known to the unknown circuit, during the summer before Columbus sailed on his first voyage, reduced what was known to not much more than a third of the whole. It was the fashion, too, with an easy reliance on their genuineness, to refer to the visions of Esdras in support of a belief in the small part—a sixth—of the surface of the globe covered by the ocean.
LAON GLOBE.
[After D'Avezac.]
Views of Columbus.
The problem lay in Columbus's mind thus: he accepted the theory of the division of the circumference of the earth into twenty-four hours, as it had come down from Marinus of Tyre, when this ancient astronomer supposed that from the eastern verge of Asia to the western extremity of Europe there was a space of fifteen hours. The discovery of the Azores had pushed the known limit a single hour farther towards the setting sun, making sixteen hours, or two thirds of the circumference of 360 degrees. There were left eight hours, or one hundred and twenty degrees, to represent the space between the Azores and Asia. This calculation in reality brought the Asiatic coast forward to the meridian of California, obliterating the width of the Pacific at that latitude, and reducing by so much the size of the globe as Columbus measured it, on the assumption that Marinus was correct. This, however, he denied. If the Historie reports Columbus exactly, he contended that the testimony of Marco Polo and Mandeville carried the verge of Asia so far east that the land distance was more than fifteen hours across; and by as much as this increased the distance, by so much more was the Asiatic shore pushed nearer the coasts of Europe. "We can thus determine," he says, "that India is even neighboring to Spain and Africa."