I kept near Cape Worldsend, taking its bearings in a variety of positions, for the ostensible purpose of ascertaining its exact position, until four o'clock, when the larboard watch went below. I saw that both Albicore and Slim turned in to get some sleep, and immediately ordered Mackerel to keep the vessel on a course corresponding to south, and to press with both steam and canvass to the utmost. The wind was about N. W., fresh and very steady, which served as a guide, the helmsman being directed to keep the wind four points on the quarter. We ran at the rate of 16 knots. I gave strict orders that Albicore and Slim should not be disturbed at the usual hour of calling the dog watch; and when they came on deck at 10 P. M. there was no land in sight. The sun to their astonishment was just setting in the bosom of the ocean: they stared at one another, and looked at me, but said nothing. They were perfectly bewildered; they knew not which way was north, south, east or west. Had they now undertaken to direct the course of the vessel, they would have been more likely to run from the land than towards it. Mackerel was delighted to see the sun set once more; it seemed like old times; and the weather had been for some days so hot that a little night was very desirable. I told them all to be perfectly at ease, for that I knew what I was about; that I could calculate every point of the compass as well as if that instrument performed its office; that we would heave to for the night, the occurrence of which was no more than I had calculated on; and finally, to give them confidence in my skill, told them, that if we did not find the sun directly over head at noon, within two days, provided no land impeded our progress, I would give up the command to Albicore, and show him the way back to Seaborn's Land. Albicore and Slim both earnestly entreated that I would instruct them how to calculate the points of the compass, if I possessed that important knowledge, so that they might be enabled to find their way back again in case any accident should befal me. I begged to be excused, choosing to keep the staff in my own hands. The truth was, having three excellent chronometers, one set to the time at Washington, one to that of Greenwich, and the other to that of Rio de Janeiro, and also an excellent watch daily regulated, which gave me the ship's diurnal time accurately, I could easily calculate my longitude, and the point on which the sun ought to bear every hour in the 24. With these calculations before me, I had but to look at my watch and the sun to determine my course. Thus in the longitude of Greenwich, when the chronometer set to Greenwich time stood at 12 o'clock noon, wherever the sun was, was north; and when that chronometer stood at midnight, wherever the sun was, was south--on the external southern hemisphere, south of the degree of the sun's declination.