For the first few days after leaving the Cape, we ran off due south, it being my intention to seek the fortieth parallel of south latitude, and run my easting down on that parallel. As icebergs have been known to make their appearance near the Cape in the spring of the year, I ordered the temperature of the air and water to be taken every hour during the night, to aid me in detecting their presence. We did not discover any icebergs, but the thermometer helped to reveal to me some of the secrets of the deep, in this part of the ocean. Much to my surprise, I found myself in a sort of Gulf Stream; the temperature of the water being from three to five degrees higher, than that of the air. My celestial observations for fixing the position of the ship, informed me at the same time that I was experiencing a south-easterly current; the current bending more and more toward the east, as I proceeded south, until in the parallel of 40°, it ran due east. The rate of this current was from thirty to fifty miles per day. This was undoubtedly a branch of the great Agulhas current.
If the reader will inspect a map, he will find that the North Indian Ocean is bounded wholly by tropical countries—Hindostan, Beloochistan, and Arabia to the Red Sea, and across that sea, by Azan and Zanguebar. The waters in this great bight of the ocean are intensely heated by the fervor of an Indian and African sun, and flow off in quest of cooler regions through the Mozambique Channel. Passing thence over the Agulhas Bank, which lies a short distance to the eastward of the Cape of Good Hope, they reach that Cape, as the Agulhas current. Here it divides into two main prongs or branches; one prong pursuing a westerly course, and joining in with the great equatorial current, which, the reader recollects, we encountered off Fernando de Noronha, and the other bending sharply to the south-east, and forming the Gulf Stream of the South Indian Ocean, in which the Alabama is at present. What it is, that gives this latter prong its sudden deflection to the southward is not well understood. Probably it is influenced, to some extent, by the southerly current, running at the rate of about a knot an hour along the west coast of Africa, and debouching at the Cape of Good Hope. Here it strikes the Agulhas current at right angles, and hence possibly the deflection of a part of that current.
But if there be a current constantly setting from the Cape of Good-Hope to the south-east, how is it that the iceberg finds its way to the neighborhood of that Cape, from the south polar regions? There is but one way to account for it. There must be a counter undercurrent. These bergs, setting deep in the water, are forced by this counter-current against the surface current. This phenomenon has frequently been witnessed in the Arctic seas. Captain Duncan, of the English whaler Dundee, in describing one of his voyages to Davis’ Strait, thus speaks of a similar drift of icebergs:—“It was awful to behold the immense icebergs working their way to the north-east from us, and not one drop of water to be seen; they were working themselves right through the middle of the ice.” Here was an undercurrent of such force as to carry a mountain of ice, ripping and crashing through a field of solid ice. Lieutenant De Haven, who made a voyage in search of Sir John Franklin, describes a similar phenomenon as follows:—“The iceberg, as before observed, came up very near to the stern of our ship; the intermediate space, between the berg and the vessel, was filled with heavy masses of ice, which, though they had been previously broken by the immense weight of the berg, were again formed into a compact body by its pressure. The berg was drifting at the rate of about four knots, and by its force on the mass of ice, was pushing the ship before it, as it appeared, to inevitable destruction.” And again, on the next day, he writes:—“The iceberg still in sight, but drifting away fast to the north-east.” Here was another undercurrent, driving a monster iceberg through a field of broken ice at the rate of four knots per hour!
When we had travelled in the Alabama some distance to the eastward, on the 39th and 40th parallels, the current made another curve—this time to the north-east. If the reader will again refer to a map, he will find that the Agulhas current, as it came along through the Mozambique Channel and by the Cape of Good Hope, was a south-westerly current. It being now a north-easterly current, he observes that it is running back whence it came, in an ellipse! We have seen, in a former part of this work, that the Gulf Stream of the North Atlantic performs a circuit around the coasts of the United States, Newfoundland, the British Islands, the coasts of Spain and Portugal, the African coast, and so on, into the equatorial current, and thence back again to the Gulf of Mexico. From my observation of currents in various parts of the world, my impression is, that the circle or ellipse is their normal law. There are, of course, offshoots from one circle, or ellipse, to another, and thus a general intermingling of the waters of the earth is going on—but the normal rule for the guidance of the water, as of the wind, is the curve.
As we approached the 40th parallel of latitude, my attention was again forcibly drawn to the phenomena of the winds. The “Brave West Winds”—as the sailors call them—those remarkable polar trade-winds, now began to prevail with wonderful regularity. On the 30th of September, we observed in latitude 39° 12′, and longitude 31° 59′. The following is the entry on my journal for that day:—“Rough weather, with the wind fresh from the N. N. W. with passing rain-squalls. Sea turbulent. Barometer 29.47; thermometer, air 55°, water 58; distance run in the last twenty-four hours, 221 miles. Weather looking better at noon. The water has resumed its usual deep-sea hue. [We had been running over an extensive tract of soundings, the water being of that pea-green tint indicating a depth of from sixty to seventy-five fathoms.] In high southern latitudes, in the Indian Ocean, the storm-fiend seems to hold high carnival all the year round. He is constantly racing round the globe, from west to east, howling over the waste of waters in his mad career. Like Sisyphus, his labors are never ended. He not only does not rest himself, but he allows old Ocean none, constantly lashing him into rage. He scatters the icebergs hither and thither to the great terror of the mariner, and converts the moisture of the clouds into the blinding snow-flake or the pelting hail. As we are driven, on dark nights, before these furious winds, we have only to imitate the Cape Horn navigator—‘tie all fast, and let her rip,’ iceberg or no iceberg. When a ship is running at a speed of twelve or fourteen knots, in such thick weather that the look-out at the cat-head can scarcely see his own nose, neither sharp eyes, nor water thermometers are of much use.”
These winds continued to blow from day to day, hurrying us forward with great speed. There being a clear sweep of the sea for several thousand miles, unobstructed by continent or island, the waves rose into long, sweeping swells, much more huge and majestic than one meets with in any other ocean. As our little craft, scudding before a gale, would be overtaken by one of these monster billows, she would be caught up by its crest, like a cock-boat, and darted half-way down the declivity that lay before her, at a speed that would cause the sailor to hold his breath. Any swerve to the right, or the left, that would cause the ship to “broach to,” or come broadside to the wind and sea, would have been fatal. These “brave west winds,” though thus fraught with danger, are a great boon to commerce. The reader has seen how the currents in this part of the ocean travel in an ellipse. We have here an ellipse of the winds. The Alabama is hurrying to the Far East, before a continuous, or almost continuous north-west gale. If she were a few hundred miles to the northward of her present position, she might be hurrying, though not quite with equal speed, before the south-east trades, to the Far West. We have thus two parallel winds blowing all the year round in opposite directions, and only a few hundred miles apart.
Storms are now admitted by all seamen to be gyratory, as we have seen. When I was cruising in the Gulf Stream, I ventured to enlarge this theory, as the reader may recollect, and suggested that rotation was the normal condition of all extra-tropical winds on the ocean, where there was nothing to obstruct them—of the moderate wind, as well as of the gale. I had a striking confirmation of this theory in the “brave west winds.” These winds went regularly around the compass, in uniform periods; the periods occupying about three days. We would take them at about N. N. W., and in the course of the “period” they would go entirely around the compass, and come back to the same point; there being an interval of calm of a few hours. The following diagram will illustrate this rotary motion.
Let Figure 1, on the opposite page, represent a circular wind—the wind gyrating in the direction of the arrows, and the circle travelling at the same time, along the dotted lines from west to east. If the northern segment of this circular wind passes over the ship, the upper dotted line from A to A2, will represent her position during its passage. At A, where the ship first takes the wind, she will have it from about north-west; and at A2, where she is about to lose it, she will have it from about south-west. The ship is supposed to remain stationary, whilst the circle is passing over her. Now, this is precisely the manner in which we found all these winds to haul in the Alabama. We would have the wind from the north-west to the south-west, hauling gradually from one point to the other, and blowing freshly for the greater part of three days. It would then become light, and, in the course of a few hours, go round to the south, to the south-east, to the east, and then settle in the north-west, as before.
