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 was carried on a vast stream where I felt the buoyancy of His hand who made all the worlds.
I realized the mathematical truth of their motions, so well known that astronomers compile tables of their positions through the years and the days, and the minutes of a day, with such precision that one coming along over the sea even five years later may, by their aid, find the standard time of any given meridian on the earth.
To find local time is a simpler matter.

The difference between local and standard time is longitude expressed in time--four minutes, we all know, representing one degree.

This, briefly, is the principle on which longitude is found independent of chronometers.