The verified longitude when abreast was somewhere between the two reckonings; this was extraordinary.

All navigators will tell you that from one day to another a ship may lose or gain more than five miles in her sailing-account, and again, in the matter of lunars, even expert lunarians are considered as doing clever work when they average within eight miles of the truth.
I hope I am making it clear that I do not lay claim to cleverness or to slavish calculations in my reckonings.

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.