[381] Cf. Kohl, Die beiden General-Karten von Amerika, p. 17, and Varnhagen’s Historia geral do Brazil, i. 432.
[382] Humboldt, Cosmos, Eng. tr., ii. 630, 670; Reisch’s Margarita philosophica (1535), p. 1416; D’Avezac’s Waltzemüller, p. 64.
[383] Cf. Lelewel, Géographie du moyen-âge, ii. 160. The rules of Gemma Frisius for discovering longitude were given in Eden’s Peter Martyr (1555), folio 360. An earlier book was Francisco Falero’s Regimiento para observar in longitud en la mar, 1535. Cf. E. F. de Navarrete’s “El problema de la longitud en la mar,” in volume 21 of the Doc. inéditos (España); and Vasco da Gama (Hakluyt Soc.), pp. 19, 25, 33, 43, 63, 138.
[384] The Germaniæ, ex variis scriptoribus perbrevis explicatio of Bilibaldus Pirckeymerus, published in 1530, has a reference to this eclipse. Carter-Brown, vol. i. no. 96; Murphy Catalogue, no. 1,992. The paragraph is as follows: “Proinde compertum est ex observatione eclypsis, quæ fuit in mense Septembri anno salutis 1494. Hispaniam insulam, quatuor ferme horarum intersticio ab Hyspali, quæ Sibilia est distare, hoc est gradibus 60, qualium est circulus maximus 360, medium vero insulæ continet gradus 20 circiter in altitudine polari. Navigatur autem spacium illud communiter in diebus 35 altitudo vero continentis oppositi, cui Hispani sanctæ Marthæ nomen indidere, circiter graduum est 12 Darieni vero terra et sinus de Uraca gradus quasi tenent 7½ in altitudine polari, unde longissimo tractu occidentem versus terra est, quæ vocatur Mexico et Temistitan, a qua etiam non longa remota est insula Jucatan cum aliis nuper repertis.” The method of determining longitude by means of lunar tables dates back to Hipparchus.
[385] These were the calculations of Regiomontanus (Müller), who calls himself “Monteregius” in his Tabulæ astronomice Alfonsi regis, published at Venice in the very year (1492) of Columbus’ first voyage. (Stevens, Bibl. Geog., no. 83.) At a later day the Portuguese accused the Spaniards of altering the tables then in use, so as to affect the position of the Papal line of Demarcation. Barras, quoted by Humboldt, Cosmos, Eng. tr. ii. 671.
Johann Stoeffler was a leading authority on the methods of defining latitude and longitude in vogue in the beginning of the new era; cf. his Elucidatio fabricæ ususque astrolabii, Oppenheim, 1513 (colophon 1512), and his edition of In Procli Diadochi sphæram omnibus numeris longe absolutissimus commentarius, Tübingen, 1534, where he names one hundred and seventy contemporary and earlier writers on the subject. (Stevens, Bibl. Geog., nos. 2,633-2,634.)
[386] The polar distance of the North Star in Columbus’ time was 3° 28´; and yet his calculations made it sometimes 5°, and sometimes 10°. It is to-day 1° 20´ distant from the true pole. United States Coast Survey Report, 1880, app. xviii.
[387] Santarem, Histoire de la cartographie, vol. ii. p. lix. Columbus would find here the centre of the earth, as D’Ailly, Mauro, and Behaim found it at Jerusalem.
[388] Cosmos, Eng. tr., ii. 658. Humboldt also points out how Columbus on his second voyage had attempted to fix his longitude by the declination of the needle (Ibid., ii. 657; v. 54). Cf. a paper on Columbus and Cabot in the Nautical Magazine, July, 1876.
It is a fact that good luck or skill of some undiscernible sort enabled Cabot to record some remarkable approximations of longitude in an age when the wildest chance governed like attempts in others. Cabot indeed had the navigator’s instinct; and the modern log-book seems to have owed its origin to his practices and the urgency with which he impressed the importance of it upon the Muscovy Company.