492 THE POPULAR SCIENCE MONTHLY. 



of places. It should be stated, as explanatory of the defective con- 

 struction 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 Ma- 

 gellan'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 oiit 

 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 Con- 

 tinent 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 had to be differentlj^ 

 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 



Fig. 10.— Mercator's First Map, a. d. 1538. 



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 w^hat has since been called the cordiform or 

 beart-shaped projection, which, while giving the whole of the geo- 

 graphical features of the earth, was, from the curve and sweep of the 

 parallels of both latitude and longitude, better adapted than anything 



