29.8 America: a.d. 1401 to 1500  (Page 5/9)

Columbus' misconception regarding the land he found is worth a little more detail. There are 360 degrees of longitude in the circumference of the earth and we know today that each degree is very close to 60 nautical miles, thus making the perimeter of the globe some 21,600 nautical miles. Erothenes, many centuries before Columbus, had estimated a degree of longitude at 59.5 miles, but Columbus accepted the calculations of a Moslem geographer, Alfragan, who postulated this figure at 56.667 Arabic miles. Columbus further misinterpreted this as the equivalent of 45 western, nautical miles thus making an error of 25%. This, plus his erroneous placement of Japan from the writings of Marco Polo, resulted in great confusion. The Canary Islands are on the same latitude as the southern tip of Japan and that was his reason for leaving from that point. He was unaware, apparently, that it was the Canary Current at that latitude that really allowed him to make the crossing. The true air-line miles from the Canaries to Japan number about 10,600, but Columbus' calculations were that it should be only 2,400. (Ref. 150 )

At any rate, the Genoese Columbus, whose Spanish name was Don Cristobal Colon, took off on his first cross-Atlantic voyage with the famous Nina, Pinta and Santa Maria vessels, leaving Spain for the Canaries on August 3, 1492. Rough water had made him take 6 days between Spain and those islands, where the warlike Guanches were only partially conquered but were gradually being reduced to slavery. We know something about his ships. The Nina, about 60 tons