This is the illustration. At eight A.M. I took my chronometer sight. At the same moment the distance recorded on the log was noted. At twelve M., when the sight for latitude was taken, I again noted the log, which showed me that since eight o’clock the Snark had run 24 miles. Her true course had been west ¾ south. I entered Table I, in the distance column, on the page for ¾ point courses, and stopped at 24, the number of miles run. Opposite, in the next two columns, I found that the Snark had made 3.5 miles of southing or latitude, and that she had made 23.7 miles of westing. To find my eight o’clock’ latitude was easy. I had but to subtract 3.5 miles from my noon latitude. All the elements being present, I worked up my longitude.
But this was my eight o’clock longitude. Since then, and up till noon, I had made 23.7 miles of westing. What was my noon longitude? I followed the rule, turning to Traverse Table No. II. Entering the table, according to rule, and going through every detail, according to rule, I found the difference of longitude for the four hours to be 25 miles. I was aghast. I entered the table again, according to rule; I entered the table half a dozen times, according to rule, and every time found that my difference of longitude was 25 miles. I leave it to you, gentle reader. Suppose you had sailed 24 miles and that you had covered 3.5 miles of latitude, then how could you have covered 25 miles of longitude? Even if you had sailed due west 24 miles, and not changed your latitude, how could you have changed your longitude 25 miles? In the name of human reason, how could you cover one mile more of longitude than the total number of miles you had sailed?
It was a reputable traverse table, being none other than Bowditch’s. The rule was simple (as navigators’ rules go); I had made no error. I spent an hour over it, and at the end still faced the glaring impossibility of having sailed 24 miles, in the course of which I changed my latitude 3.5 miles and my longitude 25 miles. The worst of it was that there was nobody to help me out. Neither Charmian nor Martin knew as much as I knew about navigation. And all the time the Snark was rushing madly along toward Tanna, in the New Hebrides. Something had to be done.
How it came to me I know not—call it an inspiration if you will; but the thought arose in me: if southing is latitude, why isn’t westing longitude? Why should I have to change westing into longitude? And then the whole beautiful situation dawned upon me. The meridians of longitude are 60 miles (nautical) apart at the equator. At the poles they run together. Thus, if I should travel up the 180° meridian of longitude until I reached the North Pole, and if the astronomer at Greenwich travelled up the 0 meridian of longitude to the North Pole, then, at the North Pole, we could shake hands with each other, though before we started for the North Pole we had been some thousands of miles apart. Again: if a degree of longitude was 60 miles wide at the equator, and if the same degree, at the point of the Pole, had no width, then somewhere between the Pole and the equator that degree would be half a mile wide, and at other places a mile wide, two miles wide, ten miles wide, thirty miles wide, ay, and sixty miles wide.
All was plain again. The Snark was in 19° south latitude. The world wasn’t as big around there as at the equator. Therefore, every mile of westing at 19° south was more than a minute of longitude; for sixty miles were sixty miles, but sixty minutes are sixty miles only at the equator. George Francis Train broke Jules Verne’s record of around the world. But any man that wants can break George Francis Train’s record. Such a man would need only to go, in a fast steamer, to the latitude of Cape Horn, and sail due east all the way around. The world is very small in that latitude, and there is no land in the way to turn him out of his course. If his steamer maintained sixteen knots, he would circumnavigate the globe in just about forty days.
But there are compensations. On Wednesday evening, June 10, I brought up my noon position by dead reckoning to eight P.M. Then I projected the Snark’s course and saw that she would strike Futuna, one of the easternmost of the New Hebrides, a volcanic cone two thousand feet high that rose out of the deep ocean. I altered the course so that the Snark would pass ten miles to the northward. Then I spoke to Wada, the cook, who had the wheel every morning from four to six.
“Wada San, to-morrow morning, your watch, you look sharp on weather-bow you see land.”
And then I went to bed. The die was cast. I had staked my reputation as a navigator. Suppose, just suppose, that at daybreak there was no land. Then, where would my navigation be? And where would we be? And how would we ever find ourselves? or find any land? I caught ghastly visions of the Snark sailing for months through ocean solitudes and seeking vainly for land while we consumed our provisions and sat down with haggard faces to stare cannibalism in the face.
I confess my sleep was not
“ . . . like a summer sky
That held the music of a lark.”