has to be allowed for currents and for drift, which the log never shows, that it is only an approximation, after all, to be corrected by one's own judgment from data of a thousand voyages; and even then the master of the ship, if he be wise, cries out for the lead and the lookout.
Unique was my experience in nautical astronomy from the deck of the Spray—so much so that I feel justified in briefly telling it here. The first set of sights, just spoken of, put her many hundred miles west of my reckoning by account. I knew that this could not be correct. In about an hour's time I took another set of observations with the utmost care; the mean result of these was about the same as that of the first set. I asked myself why, with my boasted self-dependence, I had not done at least better than this. Then I went in search of a discrepancy in the tables, and I found it. In the tables I found that the column of figures from which I had got an important logarithm was in error. It was a matter I could prove beyond a doubt, and it made the difference as already stated. The tables being corrected, I sailed on with self-reliance unshaken, and with my tin clock fast asleep. The result of these observations naturally tickled my vanity, for I knew that it was something to stand on a great ship's deck and with two assistants take lunar observations approximately near the truth. As one of the poorest of American sailors, I was proud of the little achievement alone on the sloop, even by chance though it may have been.
I was en rapport now with my surroundings, and
