To begin with, there are the compasses and the setting of the courses.We sailed from Suva on Saturday afternoon, June 6, 1908, and it took us till after dark to run the narrow, reef-ridden passage between the islands of Viti Levu and Mbengha.The open ocean lay before me.There was nothing in the way with the exception of Vatu Leile, a miserable little island that persisted in poking up through the sea some twenty miles to the west-southwest--just where I wanted to go.Of course, it seemed quite simple to avoid it by steering a course that would pass it eight or ten miles to the north.It was a black night, and we were running before the wind.The man at the wheel must be told what direction to steer in order to miss Vatu Leile.But what direction? I turned me to the navigation books."True Course" I lighted upon.The very thing!
What I wanted was the true course.I read eagerly on:
"The True Course is the angle made with the meridian by a straight line on the chart drawn to connect the ship's position with the place bound to."Just what I wanted.The Snark's position was at the western entrance of the passage 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 pricked 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 compass, 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 degrees 40 minutes 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 compass points 9 degrees 40 minutes eastward of north, and I wanted to sail due north, I should have to steer 9 degrees 40 minutes westward of the north indicated by the compass and which was not north at all.So I added 9 degrees 40minutes 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 Compass Course.There was another sly little devil lying in wait to trip me up and land me smashing on the reefs of Vatu Leile.This little devil went by the name of Deviation.I read:
"The Compass 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 ship.This purely local variation I derived from the deviation card of my standard compass and then applied to the Correct Magnetic Course.The result was the Compass Course.And yet, not yet.My standard compass was amidships on the companionway.My steering compass was aft, in the cockpit, near the wheel.When the steering compass pointed west-by-south three-quarters-south (the steering course), the standard compass pointed west-one-half-north, which was certainly not the steering course.Ikept the Snark up till she was heading west-by-south-three-quarters-south on the standard compass, which gave, on the steering compass, south-west-by-west.
The foregoing operations constitute 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 shore through a horde of man-eating sharks.
Just as the compass 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 compass 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 prone 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 identity.
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 retards as no clock could be made to accelerate and retard.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 dashing 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.
