Lully's Arte de Navegar.
It was just at the end of the thirteenth century (1295) that the Arte de Navegar of Raymond Lully, or Lullius, gave mariners a handbook, which, so far as is made apparent, was not superseded by a better even in the time of Columbus.
PRINCE HENRY THE NAVIGATOR.
[From a Chronicle in the National Library at Paris.]
Sacrobosco.
Another nautical text-book at this time was a treatise by John Holywood, a Yorkshire man, who needs to be a little dressed up when we think of him as the Latinized Sacrobosco. His Sphera Mundi was not put into type till 1472, just before Columbus's arrival in Portugal,—a work which is mainly paraphrased from Ptolemy's Almagest. It was one of the books which, by law, the royal cosmographer of Spain, at a later day, was directed to expound in his courses of instruction.
The loadstone.
The loadstone was known in western and northern Europe as early as the eleventh century, and for two or three centuries there are found in books occasional references to the magnet. We are in much doubt, however, as to the prevalence of its use in navigation. If we are to believe some writers on the subject, it was known to the Norsemen as early as the seventh century. Its use in the Levant, derived, doubtless, from the peoples navigating the Indian Ocean, goes back to an antiquity not easily to be limited.
Magnetic needle.
By the year 1200, a knowledge of the magnetic needle, coming from China through the Arabs, had become common enough in Europe to be mentioned in literature, and in another century its use did not escape record by the chroniclers of maritime progress. In the fourteenth century, the adventurous spirit of the Catalans and the Normans stretched the scope of their observations from the Hebrides on the north to the west coast of tropical Africa on the south, and to the westward, two fifths across the Atlantic to the neighborhood of the Azores,—voyages made safely under the direction of the magnet.