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 of places. It should be stated, as explanatory of the defective construction of general maps of the world at this time, and before it, that the belief of the ancients in the globular form of the earth was far from being generally accepted. Even among cosmographers there was great uncertainty as to its real form. Columbus thought it had the shape of a pear, and in fact its spherical form was not fully admitted until Magellan's vessel, in 1521, sailed around it. In Italy, however, the belief of the ancients, both as to the form and as to the motions of the earth, was revived as early as the middle of the fifteenth century.

About forty years before the map of Fra Mauro was executed, Prince Henry of Portugal, surnamed the Navigator, began to send out those expeditions along the western coast of Africa which were the beginning of that brilliant age of maritime exploration that led to the circumnavigation of the Cape of Good Hope, the discovery of the Continent of America, and the voyage of Magellan's vessel around the world. During this period of active discovery, the limits of Africa were greatly extended to the south, a vast continent was revealed by the discovery of America, and, the knowledge of the earth being thus largely augmented, a general map of the world bad to be differently arranged and represented by new methods.

The first map upon which the discoveries of Columbus appear is that of John Ruysch, in the edition of Ptolemy printed in Rome in



1508. Ruysch adopted the method of Ptolemy of projecting the earth in the form of a cone, with the Arctic at the summit, but so expanding the cone as to bring in the Western Hemisphere and show the islands and a part of the mainland discovered by Columbus and others. In 1511 Bernard Sylvanus produced in his edition of Ptolemy a general map of the world, upon what has since been called the cordiform or heart-shaped projection, which, while giving the whole of the geographical features of the earth, was, from the curve and sweep of the parallels of both latitude and longitude, better adapted than anything