It was this same Martin Behaim (Humboldt, “Cosmos,” 1860, Vol. II. p. 255) who received a charge from King John II of Portugal to compute tables for the sun’s declination and to teach pilots how to “navigate by the altitudes of the sun and stars.” It cannot now be decided whether at the close of the fifteenth century the use of the log was known as a means of estimating the distance traversed while the direction is indicated by the compass; but it is certain that the distinguished voyager Francisco Antonio Pigafetta (1491–1534) the friend and companion of Magellan—Magalhæns—speaks of the log (la catena a poppa) as of a well-known means of measuring the course passed over. Nothing is to be found regarding way-measurers in the literature of the Middle Ages until we come to the period of several “books of nautical instruction,” written or printed by this same Pigafetta (“Trattato di Navigazione,” probably before 1530); by Francisco Falero, a brother of Ruy Falero, the astronomer (“Regimiento para observar la longitud en la mar,” 1535); by Pedro da Medina, of Seville (“Arte de Navegar,” 1545); by Martin Cortez, of Bujalaroz (“Breve Compendio de la esfera, y de la arte de navegar,” 1551), and by Andres Garcia de Cespedes (“Regimiento de Navigacion y Hidrografia,” 1606). From almost all these works—some of which, if not all, have naturally become very scarce—as well as from the “Summa de Geografia” which Martin Fernandez de Enciso had published in 1519, we learn most distinctly that the “distance sailed over” was then ascertained in Spanish and Portuguese ships not by any distinct measurement, but only through estimation of the eye, according to certain established principles. Medina says (lib. iii. caps. 11–12): “In order to know the course of the ship, as to the length of distance passed over, the pilot must set down in his register how much distance the vessel hath made according to hours (i. e. guided by the hour-glass, ampoleta); and, for this, he must know that the most a ship advances in an hour is four miles, and, with feebler breezes, three or only two.” Cespedes, in his “Regimiento” (pp. 99 and 156) calls this mode of proceeding echar punto por fantasia, and he justly remarks that if great errors are to be avoided, this fantasia must depend on the pilot’s knowledge of the qualities of his ship. Columbus, Juan de la Cosa, Sebastian Cabot and Vasco da Gama, were not acquainted with the log and its mode of application, and they all estimated the ship’s speed merely by the eye, while they ascertained the distance they had made merely through the running down of the sand in the glasses known as ampoletas.
References.—For F. A. Pigafetta, for Petro de Medina and for Martin Cortez, Houzeau et Lancaster, “Bibl. Génér.,” Vol. I. pt. ii. pp. 1221–1223; “New Gen. Biog. Dict.,” Jas. Rose, London, 1850, Vol. XI. p. 113; “Biog. Univ.” (Michaud), Vol. XXXIII. p. 297; “Grand Dict. Univ.” (Larousse), Vol. XII. p. 999; “Nouv Biog. Gen.” (Hœfer), Vol. XL. p. 207. Also Dr. G. Hellmann’s “Neudrucke,” 1898, No. 10, for reproduction of Francisco Falero’s “Tratato del Esphera y del arte del marear” (Del Nordestear de las Agujas), 1535, as well as for reproduction of Martin Cortez’ “Breve Compendio” (De la piedra Yman), 1551.
A.D. 1497.—Gama (Vasco or Vasquez da), celebrated Portuguese navigator, is known positively to have made use of the compass during the voyage he undertook this year to the Indies. He says that he found the pilots of the Indian Ocean making ready use of the magnet. The first book of the history of Portugal by Jerome Osorius—wherein he gives (pp. 23–24, Book I. paragraph 15, 1581 ed.) a very extended “description de l’aiguille marine, invention des plus belles et utiles du monde”—states that, instead of a needle, they used a small magnetized iron plate, which was suspended like the needle of the Europeans, but which showed imperfectly the north.
Gilbert says (“De Magnete,” Book IV. chap. xiii.) that, as the Portuguese did not rightly understand the construction and use of the compass, some of their observations are untrustworthy and that in consequence various opinions exist relative to magnetic variation. For example, the Portuguese navigator Roderigues de Lazos—Lagos—takes it to be one-half point off the Island of St. Helena; the Dutch, in their nautical journal, make it one point there; Kendall, an expert English navigator, makes it only one-sixth of a point, using a true meridional compass. Diego Alfonso finds no variation at a point a little south-east of Cape das Agulhas,[27] and, by the astrolabe, shows that the compass points due north and south at Cape das Agulhas if it be of the Portuguese style, in which the variation is one-half point to the south-east.
References.—Azuni, “Boussole,” p. 121; Klaproth, “Boussole,” p. 64; Knight, “Mech. Dict.,” Vol. II. p. 1398; Larousse, “Dict.,” Vol. VIII. p. 977; “Voyageurs anciens et modernes” (Charton), 1855; “Le Comte Amiral D. Vasco da Gama,” par D. Maria T. da Gama, Paris, 1902.
A.D. 1497.—Cabot (Sebastian), a prominent English navigator, lands, June 24, 1497, on the coast of Labrador, between 56 degrees and 58 degrees north latitude.
At p. 150 of the 1869 London edition of Mr. J. F. Nicholl’s “Life of Seb. Cabot” it is said the latter represented to the King of England that the variation of the compass was different in many places, and was not absolutely regulated by distance from any particular meridian; that he could point to a spot of no variation, and that those whom he had trained as seamen, as Richard Chancellor and Stephen Burrough, were particularly attentive to this problem, noting it at one time thrice within a short space.
References.—Richard Hakluyt, “The Principal navigations, voyages, traffiques and discoveries of the English nation,” 1599: at pp. 237–243, for the voyage of Richard Chancelor, pilote maior, and, at p. 274, for “the voyage of Steuen Burrough, master of the pinnesse called the Serchtrift”; Livio Sanuto, “Geografia,” Venice, 1588, lib. i.; Fournier, “Hydrographie,” lib. xi.; “Library of Am. Biog.,” by Jared Sparks, Boston, 1839, Vols. II and VII as per Index at pp. 318–319; “Jean et Seb. Cabot,” par Hy. Harisse, Paris, 1882; Geo. P. Winship, “The Cabot Bibliography,” London and New York, 1900; Humboldt, “Examen Critique,” Vol. IV. p. 231, and “Cosmos,” Vol. II. (1860) pp. 640, 657–658; Biddle, “Memoir of Seb. Cabot,” 1831, pp. 52–61.
A.D. 1502.—Varthema-Vertomannus (Ludovico di) leaves Europe for the Indies, as mentioned at p. 25 of his “Travels,” translated by J. Winter Jones, London, 1863, from the original “Itenerario ... ne la India ...” Milano, 1523. He states that the Arabs who navigated the Red Sea were known to have long since made use of the mariner’s chart and compass, and he tells us, in the introduction and at p. 249, that “the captains carried the compass with the needle after our manner,” and that their chart was “marked with lines perpendicular and across.” When the polar star became invisible, they all asked the captain by what he could then steer them, and “he showed us four or five stars, among which there was one (B. Hydrus) which he said was opposite to (contrario della) our North Star, and that he sailed by the north because the magnet was adjusted and subjected to our north, i. e. because this compass was no doubt of European origin—its index pointing to the north, and being unlike that of the Chinese pointing to the south.”
References.—Cavallo, “Magnetism,” London, 1787, Chap. IV; also, “Hakluyt’s Collection of the early voyages, travels and discoveries,” London, 1811, Vol. IV. p. 547, for “The navigation and voyages of Lewes Vertomannus.”