Note Back to Main Text — Chapter VI · THE FINDING OF STRANGE COASTS.

While Columbus attached great importance to these calculations and carried Toscanelli's map with him upon his first voyage, he improved somewhat upon the estimates of distance, and thus made his case still more hopeful. Columbus's opinion of the size of the globe, the length of the Œcumene, and the width of the Atlantic ocean. Columbus was not enough of an astronomer to adopt Toscanelli's improved measurement of the size of the earth. He accepted Ptolemy's figure of 20,400 geographical miles for the equatorial girth,[463] which would make the circumference in the latitude of the Canaries about 18,000; and Columbus, on the strength of sundry passages from ancient authors which he found in Alliacus (cribbed from Roger Bacon), concluded that six sevenths of this circumference must be occupied by the Œcumene, including Cipango, so that in order to reach that wonderful island he would only have to sail over one seventh, or not much more than 2,500 miles from the Canaries.[464] An authority upon which he placed great reliance in this connection was the fourth book of The fourth book of Esdras. Esdras, which although not a canonical part of the Bible was approved by holy men, and which expressly asserted that six parts of the earth (i. e. of the length of the Œcumene, or north temperate zone) are inhabited and only the seventh part covered with water. From the general habit of Columbus's mind it may be inferred that it was chiefly upon this scriptural authority that he based his confident expectation of finding land soon after accomplishing seven hundred leagues from the Canaries. Was it not as good as written in the Bible that land was to be found there?