This ocean was also acknowledged by the author of the Kaf mountain; he says it lies between the earth and that mountain, and calls it Bahr-al-Mohith.
The end of the fifteenth century saw the dawn of a new era in knowledge and science. The discoveries of Columbus changed entirely the aspect of matters, the imagination was excited to fresh enterprises, and the hardihood of the adventurers through good or bad success was such as want of liberty could not destroy.
Nevertheless, as we have seen, Columbus imagined the earth to have the shape of a pear. Not that he obtained this idea from his own observations, but rather retained it as a relic of past traditions. It is probable that it really dates from the seventh century. We may read in several cosmographical manuscripts of that epoch, that the earth has the form of a cone or a top, its surface rising from south to north. These ideas were considerably spread by the compilations of John of Beauvais in 1479, from whom probably Columbus derived his notion.
Although Columbus is generally and rightly known as the discoverer of the New World, a very curious suit was brought by Pinzon against his heirs in 1514. Pinzon pretended that the discovery was due to him alone, as Columbus had only followed his advice in making it. Pinzon told the admiral himself that the required route was intimated by an inspiration, or revelation. The truth was that this "revelation" was due to a flock of parrots, flying in the evening towards the south-west, which Pinzon concluded must be going in the direction of an invisible coast to pass the night in the bushes. Certainly the consequences of Columbus resisting the advice of Pinzon would have been most remarkable; for had he continued to sail due west he would have been caught by the Gulf Stream and carried to Florida, or possibly to Virginia, and in this case the United States would have received a Spanish and Catholic population, instead of an English and Protestant one.
The discoveries of those days were often commemorated by the formation of heraldic devices for the authors of them, and we have in this way some curious coats of arms on record. That, for instance, of Sebastian Cano was a globe, with the legend, Primus circumdedisti me. The arms given to Columbus in 1493 consisted of the first map of America, with a range of islands in a gulf. Charles V. gave to Diego of Ordaz the figure of the Peak of Orizaba as his arms, to commemorate his having ascended it; and to the historian Oviedo, who passed thirty-four years without interruption (1513-47) in tropical America, the four beautiful stars of the Southern Cross.
We have arrived at the close of our history of the attempts that preceded the actual discovery of the form and constitution of the globe; since these were established our further progress has been in matters of detail. There now remains briefly to notice the attempts at discovering the size of the earth on the supposition, and afterwards certainty, of its being a globe.
The earliest attempt at this was made by Eratosthenes, 246 years before our era, and it was founded on the following reasoning. The sun illuminates the bottom of pits at Syene at the summer solstice; on the same day, instead of being vertical over the heads of the inhabitants of Alexandria, it is 7¼ degrees from the zenith. Seven-and-a-quarter degrees is the fiftieth part of an entire circumference; and the distance between the two towns is five thousand stadia; hence the circumference of the earth is fifty times this distance, or 250 thousand stadia.
A century before our era Posidonius arrived at an analogous result by remarking that the star Canopus touched the horizon at Rhodes when it was 7 degrees 12 minutes above that of Alexandria.
These measurements, which, though rough, were ingenious, were, followed in the eighth century by similar ones by the Arabian Caliph, Almamoun, who did not greatly modify them.
The first men who actually went round the world were the crew of the ship under Magellan, who started to the west in 1520; he was slain by the Philippine islanders in 1521, but his ship, under his lieutenant, Sebastian Cano, returned by the east in 1522. The first attempt at the actual measurement of a part of the earth's surface along the meridian was made by Fernel in 1528. His process was a singular, but simple one, namely, by counting the number of the turns made by the wheels of his carriage between Paris and Amiens. He made the number 57,020, and accurate measurements of the distance many years after showed he had not made an error of more than four turns.