...he must get his longitude, also, and this, if he chooses, he can find from the same sextant sight, by means of his chronometer. (A chronometer is a very fine and adjusted clock. One Harrison, by inventing a clock that would keep accurate time in all temperatures, and under all circumstances, received in 1773, a reward of $100.000 offered in the reign of Queen Anne for the best method of finding a ship longitude. The method is simplicity itself, in theory, and theories are all we are after now) You know, of course, that the earth revolves on its axis once in each 24 hours. As the earth turns from the W. to E. and the meridians of long. run N. and S., you can see that the 360° line of longitude passes under the [sun] one after the other, in 24 hours. And that means that a new degree passes every 4 minutes. Now, it is noon at any place on the earth when the [sun] is at the highest point in the heavens at that place. That is, it is noon at any place when the meridian, which passes...