LENGTH OF A DEGREE 29 



back to Marinus of Tyre, after Ptolemy had so con- 

 clusively demonstrated the inaccuracy of his mode 

 of reckoning. This criticism seems to me to miss 

 the point: Columbus did not adopt the 225 degrees 

 of Marinus because he rejected the correction of 

 Ptolemy. On the contrary, he made the correction 

 of Ptolemy the basis of his own calculation. Ptolemy 

 counted 180 degrees from the Insulae Fortunatae to 

 the eastern edge of the known world. He bounded 

 the Indian Sea with land on all sides. In the time 

 of Columbus the work of the medieval travelers^^ 

 was interpreted to have added extensively to the east 

 of Ptolemy's known world. Behaim, in his globe of 

 1492^^ (Fig- 4), followed Ptolemy as far as the latter 

 went with the map of southern Asia, placing Cat- 

 tigara on the i8oth meridian; but, in addition, he 

 estimated the new East, to the eastern end of Mangi, 

 at about 60 degrees. The total known world had 

 thus an extent of 240 degrees from west to east. This 

 estimate of 240 degrees, reckoned at 66^ miles to 

 the degree, equaled 16,000 miles at the equator. 

 Now, Columbus, as we have seen, accepted the value 

 of 56^ miles to the degree; consequently, dividing 

 16,000 by 56^3, he obtained the figure of 283 for the 

 number of degrees in the known world. Thus he 

 agreed with jMarinus. The distance to the far East 

 was estimated at substantially 45 degrees more than 

 by his contemporaries. In so much he reckoned the 

 world smaller than other people considered it. 



" Lelewel, op. cit., Vol. 2, pp. 125-126. 



65 Ravenstein, op. cit., Map 2 and facsimile of globe, sheets 2. 3, and 4. 



