He tells us that his attention was drawn to this subject by the writings of Averroes, but among his friends he numbered Toscanelli, a Florentine, who had turned his attention to astronomy, and had become a strong advocate of the globular form.  In Genoa itself Columbus met with but little encouragement.  He then spent many years in trying to interest different princes in his proposed attempt.  Its irreligious tendency was pointed out by the Spanish ecclesiastics, and condemned by the Council of Salamanca; its orthodoxy was confuted from the Pentateuch, the Psalms, the Prophecies, the Gospels, the Epistles, and the writings of the Fathers—­St. Chrysostom, St. Augustine, St. Jerome, St. Gregory, St. Basil, St Ambrose.

At length, however, encouraged by the Spanish Queen Isabella, and substantially aided by a wealthy seafaring family, the Pinzons of Palos, some of whom joined him personally, he sailed on August 3, 1492, with three small ships, from Palos, carrying with him a letter from King Ferdinand to the Grand-Khan of Tartary, and also a chart, or map, constructed on the basis of that of Toscanelli.  A little before midnight, October 11, 1492, he saw from the forecastle of his ship a moving light at a distance.  Two hours subsequently a signal- gun from another of the ships announced that they had descried land.  At sunrise Columbus landed in the New World.

On his return to Europe it was universally supposed that he had reached the eastern parts of Asia, and that therefore his voyage bad been theoretically successful.  Columbus himself died in that belief.  But numerous voyages which were soon undertaken made known the general contour of the American coast-line, and the discovery of the Great South Sea by Balboa revealed at length the true facts of the case, and the mistake into which both Toscanelli and Columbus had fallen, that in a voyage to the West the distance from Europe to Asia could not exceed the distance passed over in a voyage from Italy to the Gulf of Guinea—­a voyage that Columbus had repeatedly made.

In his first voyage, at nightfall on September 13, 1492, being then two and a half degrees east of Corvo, one of the Azores, Columbus observed that the compass needles of the ships no longer pointed a little to the east of north, but were varying to the west.  The deviation became more and more marked as the expedition advanced.  He was not the first to detect the fact of variation, but he was incontestably the first to discover the line of no variation.  On the return-voyage the reverse was observed; the variation westward diminished until the meridian in question was reached, when the needles again pointed due north.  Thence, as the coast of Europe was approached, the variation was to the east.  Columbus, therefore, came to the conclusion that the line of no variation was a fixed geographical line, or boundary, between the Eastern and Western Hemispheres.  In the bull of May, 1493, Pope Alexander VI. accordingly adopted this line as the perpetual boundary between the possessions of Spain and Portugal, in his settlement of the disputes of those nations.  Subsequently, however, it was discovered that the line was moving eastward.  It coincided with the meridian of London in 1662.