LENGTH OF A DEGREE 17 



terms: Ptolemy's map, Rome, 1490,^^ gave Oliosipo 

 (Lisbon) as 40° 15' N. (see Fig. i); Behaim, 1492, ^^ 

 placed it slightly above 40° N. (Fig. 2) ; Abulfeda,-" 

 in his ''Geography," had placed it at 42° 40'. The 

 Los Idolos Islands were, as we have seen (p. 6) 

 placed at 1° 5 ' by Joseph. For comparison, the data 

 may be stated in the form: 



Fifteenth-Century Estimates Modern^^ 



Lisbon 40° 15' N 38^42' N 



Los Idolos 1° 5'N 9°3o'N 



Difference 39° 10' 29° 12' 



It is not known what distance in miles Columbus 

 reckoned between these two places; I shall, there- 

 fore, take the distance as based on modern obser\^a- 

 tions. If we take the accepted value of 111,121 

 meters for a mean meridional degree and neglect the 

 fact that the two points are not on the same merid- 

 ian,- we obtain a distance between the points men- 

 tioned of 3,244,769 meters. The Italian nautical 



15 A. E. Nordenskiold : Facsimile- Atlas to the Early History of 

 Cartography, transl. by J. A. Ekelof and C. R. Markham, Stockholm, 

 1889. PI. 3. 



19 E. G. Ravenstein: Martin Behaim: His Life and His Globe, London, 

 1908, with facsimile of gores of globe; reference on sheet i, gore D. 



20 Geographic d'Aboulfeda, Vol. 2, Part I, p. 244. 



21 Lisbon from "The American Ephemeris and Nautical Almanac for 

 the Year 1925," Washington, 1923, p. 676. Los Idolos from map of the 

 islands in 1:25,000 constituting U. S. Hydrographic Office Chart No. 

 2288, Washington, 1910. 



22 Lisbon is 9° 11' W. of Greenwich, Los Idolos about 13° 48' W. 



