Note 396-5 — THE FOURTH VOYAGE OF COLUMBUS

Marinus of Tyre divided the earth into 24 meridians, 15 degrees or one hour apart. His first meridian passed the Fortunate Isles, which he supposed to be 2 1/2 degrees west of Cape St. Vincent, and his fifteenth through Catigara, southeastern China. The inhabited world embraced fifteen of these lines, 225 degrees, and the unknown portion east of India and west of Spain, nine lines, or hours, or 135 degrees. Cf. Vignaud, Toscanelli and Columbus, p. 74; Bunbury, History of Ancient Geography, II. 519 et seqq. Columbus, therefore, according to his calculations, had in 1494 completely covered this unknown section and reached India (or China), and so had demonstrated the correctness of Marinus’s views. In reality his strong preconceptions as to where he was distorted his calculations of the longitude. Ptolemy corrected Marinus’s estimate of 225 degrees from Cape St. Vincent to Sera in China, and, as noted in Columbus’s letter, placed Catigara in China (on the east side of the Gulf of Tonquin) at twelve lines or 180 degrees west of his meridian (2 1/2 degrees west of Cape St. Vincent). If Ptolemy was right, Columbus had not reached India (or more exactly China) or come, on his own calculation, within 45 degrees or 2700 geographical miles of it measured on the equator. The outline reproduction of the map of Bartholomew Columbus made after his return from this voyage given in Channing’s Student’s History of the United States, p. 27 (photographic reproduction in Bourne, Spain in America, p. 96) illustrates the Admiral’s ideas and conclusions. This region (i.e., Costa Rica and Panama) is a southern extension of Cochin-China and Cambodia and is connected with Mondo Novo, i.e., South America.