Memoirs of Service Afloat, During the War Between the States

by Raphael Semmes

Figure 2 represents two of these circular winds—and the reader must recollect that there is a constant series of them—one following the other so closely as to overlap it. Now, if the reader will cast his eye upon the letter C, near the upper dotted line, in the overlapped space, he will observe why it is, that there is always a short interval of calm before the north-west wind sets in, the second time. The wind within that space is blowing, or rather should blow, according to the theory, two opposite ways at once—from the N. N. W., and the S. S. E. The consequence is, necessarily, a calm. It is thus seen that the theory, that these “brave west winds” are a series of circular winds, harmonizes entirely with the facts observed by us. The lower dotted line is merely intended to show in what direction the wind would haul, if the southern segment, instead of the northern, passed over the ship. In that case, the ship would take the wind, from about N. N. E., as at B, and lose it at south-east, as at B². In the region of the “brave west winds,” it would seem that the northern segment always passes over that belt of the ocean. The received theory of these south polar-winds, is not such as I have assumed. Former writers have not supposed them to be circular winds at all. They suppose them to pass over the south-east trade-winds, as an upper current, and when they have reached the proper parallel, to descend, become surface-winds, and blow home, as straight winds, to the pole. But I found a difficulty in reconciling this theory with the periodical veering of the wind entirely around the compass, as above described. If these were straight winds, blowing contrary to the trades, why should they not blow steadily like the trades? But if we drop the straight-wind theory, and take up the circular hypothesis, all the phenomena observed by us will be in conformity with the latter. The periodical hauling of the wind will be accounted for, and if we suppose that the northern half of the circle invariably passes over the ship, in the passage-parallels, we shall see how it is that the wind is blowing nearly all the time from the westward. To account for the fact that the northern half of the circle invariably passes over these parallels, we have only to suppose the circle to be of sufficient diameter to extend to, or near the pole.

Here is the figure. It extends from the parallel of 40°, to the pole; it is therefore fifty degrees, or three thousand miles, in diameter. Half-way from its northern to its southern edge, would be the 65th parallel. Along this parallel, represented by the dotted line, which passes through the centre of the circle, the vortex, V, or calm spot, would travel. There should be calms, therefore, about the 65th parallel. In the southern half of the circle, or that portion of it between the vortex and the pole, easterly winds should prevail. Navigators between the parallels of 65° and 75°, speak of calms as the normal meteorological condition. All nature seems frozen to death, the winds included. Unfortunately, we have no reliable data for the parallels beyond, and do not know, therefore, whether easterly winds are the prevalent winds or not. It is probable, as we approached the pole, that we should find another calm. The winds, [see the arrows,] as they come hurrying along the circle, from its northern segment, bring with them an impetus toward the east, derived from the diurnal motion of the earth, on its axis. As these winds approach the pole, this velocity increases, in consequence of the diminishing diameter of the parallels. To illustrate. If a particle of air on the equator, having a velocity eastward of fifteen miles per minute—and this is the rate of the revolution of the earth on its axis—should be suddenly transported to a point, distant five miles from the pole, it would have sufficient velocity to carry it entirely around the pole in one minute. Here we have two forces acting in opposition to each other—the impetus of the wind toward the east, given to it by the diurnal motion of the earth, and an impetus from the east, given to it by whatever causes are hurrying it around the circle. These two forces necessarily neutralize each other, and a calm is the consequence. It is in this calm region near the poles, that the winds probably ascend, to take their flight back to the equator, in obedience to that beautiful arrangement for watering the earth, which I described some pages back.

There remains but one other fact to be reconciled with our theory. It has been seen that consecutive circles of wind passed over the Alabama, in periods of three days each. Did this time correspond with the known rate of travel of the circles? Almost precisely. Referring again to the last diagram, it will be remembered that the Alabama was near the northern edge of the circle. Let A A represent her position at the beginning and end of each wind. The chord of the segment, represented by the dotted line, is about 1500 miles in length. The circles travel at the rate of about 20 miles per hour. Multiply the number of hours—72—in three days, by 20, and we shall have 1440 miles. It is not pretended, of course, that these figures are strictly accurate, but they are sufficiently so to show, at least, that there is no discordance between the fact and the theory.

Soon after leaving the Cape of Good Hope, the storm-birds began to gather around us in considerable numbers—the Cape pigeon, the albatross, and occasionally the tiny petrel, so abundant in the North Atlantic. These birds seemed to be quite companionable, falling in company with the ship, and travelling with her for miles at a time. On the occasion of one of the short calms described, we caught an albatross, with hook and line, which measured ten feet across the wings. The monster bird was very fat, and it was quite a lift to get it inboard. Though very active on the wing, and rising with great facility from the water, in which it sometimes alights, it lay quite helpless when placed upon the deck. It did not seem to be much alarmed at the strangeness of its position, but looked at us with the quiet dignity and wisdom of an owl, as though it would interrogate us as to what we were doing in its dominions. These birds live in the midst of the great Indian Ocean, thousands of miles away from any land—only making periodical visits to some of the desert islands; or, it may be, to the Antarctic Continent, to incubate and rear their young.

I have described at some length the nature of the great circles of wind which form the normal meteorological condition of the region of ocean through which we were passing. This normal condition was sometimes interfered with by the passage of cyclones of smaller diameter—a circle within a circle; both circles, however, obeying the same laws. We took one of these cyclones on the 5th of October. I do not design to repeat, here, the description of a cyclone, and only refer to that which we now encountered, for the purpose of showing that the Alabama ran a race with it, and was not very badly beaten. This race is thus described in my journal: “Morning dull, cloudy, and cool. The wind hauled, last night, to north, and is blowing a fresh breeze at noon. Barometer, 30.14. Thermometer, air 54°, water 60°. Current during the last twenty-four hours, thirty miles east. The weather continued to thicken in the afternoon, and the wind to increase, with a falling barometer, indicating the approach of a gale. At nine P. M., the squalls becoming heavy, we furled the top-gallant sails and foresail, close-reefed the topsails, and took the bonnets off the trysails. Under this reduced sail we continued to scud the ship all night—the barometer still falling, the wind increasing, and a heavy sea getting up. We had entered the north-eastern edge of a cyclone. The next morning the wind was still north by west, having hauled only a single point in twelve hours; showing that we had been running, neck and neck, with the gale.

If the reader will recollect that, in these circular gales, the change of the wind is due to the passage of the circle over the ship, he will have no difficulty in conceiving that, if the ship travels as fast as the circle, and in the same direction, the wind will not change at all. Now, as the wind had changed but a single point in twelve hours, it is evident that the Alabama had been travelling nearly as fast as the circular gale. The race continued all the next day—the wind not varying half a point, and the barometer settling by scarcely perceptible degrees. Toward night, however, the barometer began to settle quite rapidly, and the wind increased, and began to haul to the westward. The gale had acquired accelerated speed, and was now evidently passing ahead of us quite rapidly; for by half-past four A. M. the wind was at west, having hauled nearly a quadrant in twelve hours. At this point we had the lowest barometer, 29.65. The centre of the storm was then just abreast of us, bearing about south, and distant perhaps a hundred miles. At five A. M., or in half an hour afterward, the wind shifted suddenly from W. to W. S. W., showing that the vortex had passed us, and that the Alabama was at last beaten! The wind being still somewhat fresher than I desired, I hove the ship to, on the port tack, to allow the gale to draw farther ahead of me. After lying to three hours, the barometer continuing to rise, and the wind to moderate, we filled away, and shaking out some of the reefs, continued on our course.

On the 12th of October, we passed the remarkable islets of St. Peter and St. Paul, a sort of half-way mile-posts between the Cape of Good Hope and the Strait of Sunda. These islets are the tops of rocky mountains, shooting up from great depths in the sea. They are in the midst of a dreary waste of waters, having no other land within a thousand miles and more, of them. They are composed of solid granite, without vegetation, and inhabited only by the wild birds of the ocean. I cannot imagine a more fitting station for a meteorologist. He would be in the midst of constant tempests, and might study the laws of his science, without interruption from neighboring isle or continent. There being an indifferent anchorage under the lee of St. Paul, we scanned the island narrowly with our glasses, as we passed, not knowing but we might find some adventurous Yankee whaler, or seal-catcher, trying out blubber, or knocking a seal on the head. These islands are frequently sighted by India-bound ships, and it was my intention to cruise a few days in their vicinity, but the bad weather hurried me on.

We took another gale, on the night after leaving them, and had some damage done to our head-rail and one of our quarter-boats. The scene was a sublime one to look upon. The seas—those long swells before described—were literally running mountains high, the wind was howling with more than usual fury, and a dense snow-storm was pelting us from the blackest and most angry-looking of clouds. I was now in longitude 83° E., and bore away more to the northward. Although the thermometer had not settled below 50°, we felt the cold quite piercingly—our clothing being constantly saturated with moisture. On the 14th of October, we had the first tolerably fine day we had experienced for the last two weeks, and we availed ourselves of it, to uncover the hatches and ventilate the ship, getting up from below, and airing the damp bedding and mildewed clothing. The constant straining of the ship, in the numerous gales she had encountered, had opened the seams in her bends, and all our state-rooms were leaking more or less, keeping our beds and clothing damp. On the next day, another gale overtook us, in which we lay to ten hours, to permit it, as we had done the gale we ran the race with, to pass ahead of us.

And thus it was, that we ran down our easting, in the region of the “brave west winds,” with every variety of bad weather, of the description of which, the reader must, by this time, be pretty well tired. On the 17th of October, I was nearly antipodal with my home in Alabama. By the way, has the reader ever remarked that land is scarcely ever antipodal with land? Let him take a globe, and he will be struck with the fact, that land and water have been almost invariably arranged opposite to each other. May not this arrangement have something to do with the currents, and the water-carriers, the winds?