LENGTH OF A DEGREE 19 



terranean but were far from maintaining the same 

 character for the extra-Mediterranean, or Atlantic, 

 area.24 An estimate of the relative error may readily 

 be obtained by comparing the portolano charts with 

 modern maps. 



For this purpose, I have taken the distance In 

 miles from Land's End, Cornwall, to the Strait of 

 Gibraltar (both on the same meridian), and that 

 from the Strait of Gibraltar to the Alexandretta cor- 

 ner of the Mediterranean (both nearly on the same 

 parallel). The Mediterranean extends from longi- 

 tude 5° 31 ' W. to 36° 10 ' E., a distance of 2333 miles, 

 reckoning 56 statute miles to a degree on the parallel 

 of 36°. The Strait of Gibraltar is situated in lati- 

 tude 35° 57' N.; Land's End, 50° 17' N. approxi- 

 mately. The difference is 14° 20', or 991 miles. The 

 ratio of the distance, obtained by dividing 991 by 

 2333, is 425. For comparison, we may calculate the 

 same ratio from a series of portolano charts and 

 mappemondes : 



2< Nordenskiold, Periplus, PI. 4; Lelewel, op. ciL, Vol. 2, p. 33; E. L. 

 Stevenson: Portolan Charts: Their Origin and Characteristics, Pubis. 

 Hispanic Soc. of Amer. No. 82, New York, 1911, pp. 19-20. 



