The time on board was evidently kept by hour-glasses of half or a whole hour. Thus under date of Tuesday, January 22, when homeward bound, his log reads: “They made 8 miles an hour during five glasses ... afterwards they went N.E. by N. for six glasses.... Then during four glasses of the second watch N.E. at six miles an hour.” But the reader must be cautious not to accept the speed given as conclusive. One of the greatest drawbacks to navigation in those days was the absence of any instrument which would record the speed through the water. The log had yet to be invented, and the mariner could only make a conjectural estimate of the ship’s speed by looking over the side and noting the time it took the bubbles to come aft from the bow, or by throwing a piece of wood overboard from the bows and noticing how long it took for the stern to be abreast of that object. Many a steamship traveller gambling on the ship’s speed does the same thing to-day; many a fore-and-aft sailorman with no patent log still employs a similar method.
Columbus’s journal shows the kind of helmsman which he had to put up with. On September 9, when the ship’s course was west, the narrator on board wrote: “The sailors steered badly, letting the ship fall off to N.E., and even more; respecting which the Admiral complained many times.” On September 13 Columbus observed a variation in the compass. “On this day, at the commencement of the night, the needles turned a half point to N.W., and in the morning they turned somewhat more N.W.” For up till then no one had observed the variation of the needle.
[Illustration: FIFTEENTH-CENTURY CARAVEL.
Drawn from a woodcut after a delineation by Columbus in the Latin translation of his letter dated March 1, 1493, to Don Raphael de Sanxis (Treasurer of the King of Spain), in the Library at Milano.
No navigator could have been more careful than Columbus. Ever on the alert, he was far too anxious about the safety of his fleet to neglect one single precaution. As they voyaged, the difference in the saltness of the sea was noted; and though for eleven days the wind blew steadily from aft so that the sails required no trimming, yet all the while Columbus was busy with astrolabe and sounding lead endeavouring to fix his position in regard to the land which they had long since left. From Wednesday, February 13, till the following Saturday, he never slept a wink, being far too anxious to leave the navigation to others. The pilots of the _Nina_ and _Pinta_ on the voyage out used to work out their positions for themselves. On September 19 the _Nina_ made the Canaries to be 440 leagues astern, the _Pinta_ estimated the distance as 420, but on board Columbus’s ship the reckoning was 400 leagues, and this was the most correct of the three. (It should be added that Columbus used Italian miles, reckoning four Italian miles to one league.) He compared notes with the pilots under him, and manœuvred his ship so that the captain of the _Pinta_ was able to pass his chart on board the _Santa Maria_ at the end of a line. Columbus, after conferring with his own pilots and mariners, plotted on the chart the position of the ship. Here and there all the way through Columbus’s journal, both in those lines written by his own hand and in those in another handwriting, there rises up, quite clearly, evidence of the knowledge which this man had been collecting before setting out. “The admiral was aware,” says the Journal, “that most of the islands held by the Portuguese were discovered by the flight of birds.” Just as the Viking seamen had discovered land in exactly the reverse manner--by letting loose birds from the ship.