The mariner's compass, invented, according to the generally received opinion, about 1302, by one Flavio Gioja of Amalfi, enabled vessels to sail at a distance from the coasts, and to guide themselves when out of sight of land. Martin Behaim, with two physicians in the service of Prince Henry of Portugal, had also added to nautical science by discovering the way of directing the voyager's course according to the position of the sun in the heavens, and by applying the astrolabe to the purposes of navigation. These improvements being adopted, the commercial question of the western route increased daily in importance in Spain, Portugal, and Italy, countries in which three-quarters of the science is made up of imagination. There was discussion, there were writings. The excited world of commerce disputed with the world of science. Facts, systems, doctrines, were grouped together. The time was come when there was needed one single intelligence to collect together and assimilate the various floating ideas. This intelligence was found. At length all the scattered notions were gathered together in the mind of one man, who possessed in a remarkable degree genius, perseverance, and boldness. [Illustration: Christopher Columbus.] This man was no other than Christopher Columbus, born, probably near Genoa, about the year 1436. We say "probably," for the towns of Cogoreo and Nervi dispute with Savona and Genoa, the honour of having given him birth. The date of his birth varies, with different biographers, from 1430 to 1445, but the year 1436 would appear to be the correct one, according to the most reliable documents. The family of Columbus was of humble origin; his father, Domenic Columbus, a manufacturer of woollen stuffs, seems, however, to have been in sufficiently easy circumstances to enable him to give his children a more than ordinarily good education. The young Christopher, the eldest of the family, was sent to the University of Pavia, there to study Grammar, Latin, Geography, Astronomy, and Navigation.