The Cruise of the Snark Part 12

"The True Course is the angle made with the meridian by a straight line on the chart drawn to connect the s.h.i.+p's position with the place bound to."

Just what I wanted. The _Snark's_ position was at the western entrance of the pa.s.sage between Viti Levu and Mbengha. The immediate place she was bound to was a place on the chart ten miles north of Vatu Leile. I p.r.i.c.ked that place off on the chart with my dividers, and with my parallel rulers found that west-by-south was the true course. I had but to give it to the man at the wheel and the _Snark_ would win her way to the safety of the open sea.

But alas and alack and lucky for me, I read on. I discovered that the compa.s.s, that trusty, everlasting friend of the mariner, was not given to pointing north. It varied. Sometimes it pointed east of north, sometimes west of north, and on occasion it even turned tail on north and pointed south. The variation at the particular spot on the globe occupied by the _Snark_ was 9 40' easterly. Well, that had to be taken in to account before I gave the steering course to the man at the wheel.

I read:

"The Correct Magnetic Course is derived from the True Course by applying to it the variation."

Therefore, I reasoned, if the compa.s.s points 9 40' eastward of north, and I wanted to sail due north, I should have to steer 9 40' westward of the north indicated by the compa.s.s and which was not north at all. So I added 9 40' to the left of my west-by-south course, thus getting my correct Magnetic Course, and was ready once more to run to open sea.

Again alas and alack! The Correct Magnetic Course was not the Compa.s.s Course. There was another sly little devil lying in wait to trip me up and land me smas.h.i.+ng on the reefs of Vatu Leile. This little devil went by the name of Deviation. I read:

"The Compa.s.s Course is the course to steer, and is derived from the Correct Magnetic Course by applying to it the Deviation."

Now Deviation is the variation in the needle caused by the distribution of iron on board of s.h.i.+p. This purely local variation I derived from the deviation card of my standard compa.s.s and then applied to the Correct Magnetic Course. The result was the Compa.s.s Course. And yet, not yet.

My standard compa.s.s was amids.h.i.+ps on the companionway. My steering compa.s.s was aft, in the c.o.c.kpit, near the wheel. When the steering compa.s.s pointed west-by-south three-quarters-south (the steering course), the standard compa.s.s pointed west-one-half-north, which was certainly not the steering course. I kept the _Snark_ up till she was heading west-by-south-three-quarters-south on the standard compa.s.s, which gave, on the steering compa.s.s, south-west-by-west.

The foregoing operations const.i.tute the simple little matter of setting a course. And the worst of it is that one must perform every step correctly or else he will hear "Breakers ahead!" some pleasant night, a nice sea-bath, and be given the delightful diversion of fighting his way to the sh.o.r.e through a horde of man-eating sharks.

Just as the compa.s.s is tricky and strives to fool the mariner by pointing in all directions except north, so does that guide post of the sky, the sun, persist in not being where it ought to be at a given time. This carelessness of the sun is the cause of more trouble-at least it caused trouble for me. To find out where one is on the earth's surface, he must know, at precisely the same time, where the sun is in the heavens. That is to say, the sun, which is the timekeeper for men, doesn't run on time.

When I discovered this, I fell into deep gloom and all the Cosmos was filled with doubt. Immutable laws, such as gravitation and the conservation of energy, became wobbly, and I was prepared to witness their violation at any moment and to remain unastonished. For see, if the compa.s.s lied and the sun did not keep its engagements, why should not objects lose their mutual attraction and why should not a few bushel baskets of force be annihilated? Even perpetual motion became possible, and I was in a frame of mind p.r.o.ne to purchase Keeley-Motor stock from the first enterprising agent that landed on the _Snark's_ deck. And when I discovered that the earth really rotated on its axis 366 times a year, while there were only 365 sunrises and sunsets, I was ready to doubt my own ident.i.ty.

This is the way of the sun. It is so irregular that it is impossible for man to devise a clock that will keep the sun's time. The sun accelerates and r.e.t.a.r.ds as no clock could be made to accelerate and r.e.t.a.r.d. The sun is sometimes ahead of its schedule; at other times it is lagging behind; and at still other times it is breaking the speed limit in order to overtake itself, or, rather, to catch up with where it ought to be in the sky. In this last case it does not slow down quick enough, and, as a result, goes das.h.i.+ng ahead of where it ought to be. In fact, only four days in a year do the sun and the place where the sun ought to be happen to coincide. The remaining 361 days the sun is pothering around all over the shop. Man, being more perfect than the sun, makes a clock that keeps regular time. Also, he calculates how far the sun is ahead of its schedule or behind. The difference between the sun's position and the position where the sun ought to be if it were a decent, self-respecting sun, man calls the Equation of Time. Thus, the navigator endeavouring to find his s.h.i.+p's position on the sea, looks in his chronometer to see where precisely the sun ought to be according to the Greenwich custodian of the sun. Then to that location he applies the Equation of Time and finds out where the sun ought to be and isn't. This latter location, along with several other locations, enables him to find out what the man from Kansas demanded to know some years ago.

The _Snark_ sailed from Fiji on Sat.u.r.day, June 6, and the next day, Sunday, on the wide ocean, out of sight of land, I proceeded to endeavour to find out my position by a chronometer sight for longitude and by a meridian observation for lat.i.tude. The chronometer sight was taken in the morning when the sun was some 21 above the horizon. I looked in the Nautical Almanac and found that on that very day, June 7, the sun was behind time 1 minute and 26 seconds, and that it was catching up at a rate of 14.67 seconds per hour. The chronometer said that at the precise moment of taking the sun's alt.i.tude it was twenty-five minutes after eight o'clock at Greenwich. From this date it would seem a schoolboy's task to correct the Equation of Time. Unfortunately, I was not a schoolboy. Obviously, at the middle of the day, at Greenwich, the sun was 1 minute and 26 seconds behind time. Equally obviously, if it were eleven o'clock in the morning, the sun would be 1 minute and 26 seconds behind time plus 14.67 seconds. If it were ten o'clock in the morning, twice 14.67 seconds would have to be added. And if it were 8: 25 in the morning, then 3 times 14.67 seconds would have to be added. Quite clearly, then, if, instead of being 8:25 A.M., it were 8:25 P.M., then 8 times 14.67 seconds would have to be, not added, but _subtracted_; for, if, at noon, the sun were 1 minute and 26 seconds behind time, and if it were catching up with where it ought to be at the rate of 14.67 seconds per hour, then at 8.25 P.M. it would be much nearer where it ought to be than it had been at noon.

So far, so good. But was that 8:25 of the chronometer A.M., or P.M.? I looked at the _Snark's_ clock. It marked 8:9, and it was certainly A.M.

for I had just finished breakfast. Therefore, if it was eight in the morning on board the _Snark_, the eight o'clock of the chronometer (which was the time of the day at Greenwich) must be a different eight o'clock from the _Snark's_ eight o'clock. But what eight o'clock was it? It can't be the eight o'clock of this morning, I reasoned; therefore, it must be either eight o'clock this evening or eight o'clock last night.

It was at this juncture that I fell into the bottomless pit of intellectual chaos. We are in east longitude, I reasoned, therefore we are ahead of Greenwich. If we are behind Greenwich, then to-day is yesterday; if we are ahead of Greenwich, then yesterday is to-day, but if yesterday is to-day, what under the sun is to-day!-to-morrow? Absurd!

Yet it must be correct. When I took the sun this morning at 8:25, the sun's custodians at Greenwich were just arising from dinner last night.

"Then correct the Equation of Time for yesterday," says my logical mind.

"But to-day is to-day," my literal mind insists. "I must correct the sun for to-day and not for yesterday."

"Yet to-day is yesterday," urges my logical mind.

"That's all very well," my literal mind continues, "If I were in Greenwich I might be in yesterday. Strange things happen in Greenwich.

But I know as sure as I am living that I am here, now, in to-day, June 7, and that I took the sun here, now, to-day, June 7. Therefore, I must correct the sun here, now, to-day, June 7."

"Bos.h.!.+" snaps my logical mind. "Lecky says-"

"Never mind what Lecky says," interrupts my literal mind. "Let me tell you what the Nautical Almanac says. The Nautical Almanac says that to-day, June 7, the sun was 1 minute and 26 seconds behind time and catching up at the rate of 14.67 seconds per hour. It says that yesterday, June 6, the sun was 1 minute and 36 seconds behind time and catching up at the rate of 15.66 seconds per hour. You see, it is preposterous to think of correcting to-day's sun by yesterday's time-table."

"Fool!"

"Idiot!"

Back and forth they wrangle until my head is whirling around and I am ready to believe that I am in the day after the last week before next.

I remembered a parting caution of the Suva harbour-master: "_In east longitude take from the Nautical Almanac the elements for the preceding day_."

Then a new thought came to me. I corrected the Equation of Time for Sunday and for Sat.u.r.day, making two separate operations of it, and lo, when the results were compared, there was a difference only of four-tenths of a second. I was a changed man. I had found my way out of the crypt. The _Snark_ was scarcely big enough to hold me and my experience. Four-tenths of a second would make a difference of only one-tenth of a mile-a cable-length!

All went merrily for ten minutes, when I chanced upon the following rhyme for navigators:

"Greenwich time least Longitude east; Greenwich best, Longitude west."

Heavens! The _Snark's_ time was not as good as Greenwich time. When it was 8:25 at Greenwich, on board the _Snark_ it was only 8:9. "Greenwich time best, longitude west." There I was. In west longitude beyond a doubt.

"Silly!" cries my literal mind. "You are 8:9 A.M. and Greenwich is 8:25 P.M."

"Very well," answers my logical mind. "To be correct, 8.25 P.M. is really twenty hours and twenty-five minutes, and that is certainly better than eight hours and nine minutes. No, there is no discussion; you are in west longitude."

Then my literal mind triumphs.

"We sailed from Suva, in the Fijis, didn't we?" it demands, and logical mind agrees. "And Suva is in east longitude?" Again logical mind agrees. "And we sailed west (which would take us deeper into east longitude), didn't we? Therefore, and you can't escape it, we are in east longitude."

"Greenwich time best, longitude west," chants my logical mind; "and you must grant that twenty hours and twenty-five minutes is better than eight hours and nine minutes."

"All right," I break in upon the squabble; "we'll work up the sight and then we'll see."

And work it up I did, only to find that my longitude was 184 west.

"I told you so," snorts my logical mind.

I am dumbfounded. So is my literal mind, for several minutes. Then it enounces:

"But there is no 184 west longitude, nor east longitude, nor any other longitude. The largest meridian is 180 as you ought to know very well."

Having got this far, literal mind collapses from the brain strain, logical mind is dumb flabbergasted; and as for me, I get a bleak and wintry look in my eyes and go around wondering whether I am sailing toward the China coast or the Gulf of Darien.

Then a thin small voice, which I do not recognize, coming from nowhere in particular in my consciousness, says:

"The total number of degrees is 360. Subtract the 184 west longitude from 360, and you will get 176 east longitude."

"That is sheer speculation," objects literal mind; and logical mind remonstrates. "There is no rule for it."

"Darn the rules!" I exclaim. "Ain't I here?"

"The thing is self-evident," I continue. "184 west longitude means a lapping over in east longitude of four degrees. Besides I have been in east longitude all the time. I sailed from Fiji, and Fiji is in east longitude. Now I shall chart my position and prove it by dead reckoning."

But other troubles and doubts awaited me. Here is a sample of one. In south lat.i.tude, when the sun is in northern declination, chronometer sights may be taken early in the morning. I took mine at eight o'clock.

Now, one of the necessary elements in working up such a sight is lat.i.tude. But one gets lat.i.tude at twelve o'clock, noon, by a meridian observation. It is clear that in order to work up my eight o'clock chronometer sight I must have my eight o'clock lat.i.tude. Of course, if the _Snark_ were sailing due west at six knots per hour, for the intervening four hours her lat.i.tude would not change. But if she were sailing due south, her lat.i.tude would change to the tune of twenty-four miles. In which case a simple addition or subtraction would convert the twelve o'clock lat.i.tude into eight o'clock lat.i.tude. But suppose the _Snark_ were sailing southwest. Then the traverse tables must be consulted.

This is the ill.u.s.tration. 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 lat.i.tude 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 south. I entered Table I, in the distance column, on the page for 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 lat.i.tude, and that she had made 23.7 miles of westing. To find my eight o'clock' lat.i.tude was easy. I had but to subtract 3.5 miles from my noon lat.i.tude. All the elements being present, I worked up my longitude.