I think I have already
stated that I kept my longitude, at least, mostly by intuition. A
rotator log always towed astern, but so much 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.
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