THE FIGURE OF THE EARTH 9 



been investigated to a height of more than twelve miles from the 

 earth's surface. 



The evolution of ideas concerning the earth's figure. The 

 ideas which in all ages have been promulgated concerning the 

 figure of the earth have been many and varied. Though among 

 them are not wanting the purely speculative and fantastic, it will 

 be interesting to pass in review such theories as have grown directly 

 out of observation. 



The ancient Hebrews and the Babylonians were dwellers of the 

 desert, and in the mountains which bounded their horizon they 

 saw the confines of the earth. Pushing at last westward beyond 

 the mountains, they found the Mediterranean, and thus arrived at 

 the view that the earth was a disk with a rim of mountains which 

 was floated upon water. The rare but violent rainfalls to which 

 they were accustomed the desert cloudburst further led them 

 to the belief that the mountain rim was continued upward in a 

 dome or firmament of transparent crystal upon which the heavenly 

 bodies were hung and from which out of " windows of heaven " 

 the water " which is above the earth " was poured out upon the 

 earth's surface. Fantastic as this theory may seem to-day, it 

 was founded upon observation, and it well illustrates the dangers 

 of reasoning from observation within too limited a field. 



As soon as men began to sail the sea, it was noticed that the 

 water surface is convex, for the masts of ships were found to remain 

 visible long after their hulls had disappeared below the horizon. 

 It is difficult to say how soon the idea of the earth's rotundity was 

 acquired, but it is certainly of great antiquity. The Dominican 

 monk Vincentius of Beauvais, in a work completed in 1244, declared 

 that the surfaces of the earth and the sea were both spherical. 

 The poet Dante made it clear that these surfaces were one, and 

 in his famous address upon " The Water and the Land," which 

 was delivered in Verona on the 20th of January, 1320, he added 

 a statement that the continents rise higher than the ocean. His 

 explanation of this was that the continents are pulled up by the 

 attraction of the fixed stars after the manner of attraction of 

 magnets, thus giving an early hint of the force of gravitation. 



The earth's rotundity may be said to have been first proven 

 when Magellan's ships in 1521 had accomplished the circumnavi- 

 gation of the globe. Circumnavigation, soon after again carried 



