COLUMBUS'S TRACK IN 1492.
The result of Monday's sail, which he knew to be sixty leagues, he noted as forty-eight, so that the distance from home might appear less than it was. He continued to practice this deceit.
His dead reckoning.
The distances given by Columbus are those of dead reckoning beyond any question. Lieutenant Murdock, of the United States navy, who has commented on this voyage, makes his league the equivalent of three modern nautical miles, and his mile about three quarters of our present estimate for that distance. Navarrete says that Columbus reckoned in Italian miles, which are a quarter less than a Spanish mile. The Admiral had expected to make land after sailing about seven hundred leagues from Ferro; and in ordering his vessels in case of separation to proceed westward, he warned them when they sailed that distance to come to the wind at night, and only to proceed by day.
The log as at present understood in navigation had not yet been devised. Columbus depended in judging of his speed on the eye alone, basing his calculations on the passage of objects or bubbles past the ship, while the running out of his hour glasses afforded the multiple for long distances.
1492. September 13.
Reaches point of no variation of the needle.
Knowledge of the magnet.
On Thursday, the 13th of September, he notes that the ships were encountering adverse currents. He was now three degrees west of Flores, and the needle of the compass pointed as it had never been observed before, directly to the true north. His observation of this fact marks a significant point in the history of navigation. The polarity of the magnet, an ancient possession of the Chinese, had been known perhaps for three hundred years, when this new spirit of discovery awoke in the fifteenth century. The Indian Ocean and its traditions were to impart, perhaps through the Arabs, perhaps through the returning Crusaders, a knowledge of the magnet to the dwellers on the shores of the Mediterranean, and to the hardier mariners who pushed beyond the Pillars of Hercules, so that the new route to that same Indian Ocean was made possible in the fifteenth century. The way was prepared for it gradually. The Catalans from the port of Barcelona pushed out into the great Sea of Darkness under the direction of their needles, as early at least as the twelfth century. The pilots of Genoa and Venice, the hardy Majorcans and the adventurous Moors, were followers of almost equal temerity.