Equatorial mount

“ See the immense equatorial flow to the east of Australia, and which I have called the Polynesian Drift. It is bound for the icy barriers of that unknown sea, there to temper climates, grow cool, and return again, refreshing man and beast by the way, either as the Humboldt current, or the ice-bearing current which enters the Atlantic around Cape Horn, and changes into warm again as it enters the Gulf of Guinea. It was owing to this great southern flow from the coral regions that Captain Ross was enabled to penetrate so much farther south than Captain Wilkes on his voyage to the Antarctic. ”

“ If we here recognise the mainspring of the Gulf Stream mechanism, or rather of the whole system of oceanic circulation-for the movements observed in the Atlantic have their exact counterpart in the Pacific—we shall have no difficulty in accounting for all the motions which that mechanism exhibits. We need no longer look upon the Gulf Stream as the rebound of the equatorial current from the shores of North America. Knowing that there is an underflow towards the equator, we see that there must be a surface-flow towards the Poles. ”

“ Blowing with regular force on the surface of the sea, they cause it to move in the same direction in which they are travelling; and, this motion once acquired, the ocean stream keeps up its course far beyond where its original propelling power directly acted upon it. The ‘Great Equatorial Current’ is produced by the south-east trade, the Gulf Stream, as I’ve just explained to you, by the western or passage winds ”

“ It is known that the southeast trade-winds prevail in the Atlantic ocean, between the African and American continents, south of the equator to the tropic of Capricorn, and the northeast trade to the southward of the tropic of Cancer. It is of course generally understood, that the sun heats the equatorial regions to a higher temperature than is found anywhere else, and that the air over these regions is consequently expanded and rendered lighter than that which envelops the regions at a distance. ”

“ Therefore it is fair to suppose that much of the vapor which is taken up on that side of the equator is precipitated on this. The evaporating surface in the southern hemisphere is greater, much greater, than it is in the northern; still, all the great rivers are in the northern hemisphere, the Amazon being regarded as common to both; and this fact, as far as it goes, tends to corroborate the suggestion as to the crossing of the trade-winds at the equatorial calms. ”

“ This surprising fact seems most improbable to those who are not acquainted with the Protectorate, but it must be remembered that temperature and climate depend on elevation as much as on geographical position. The best-known equatorial countries—such as West Africa, Brazil, and the Malay Archipelago—are comparatively low and flat. It is only rarely, as in Bolivia and East Africa, that we find the much rarer combination of equatorial position and considerable altitude. ”

“ But is it reasonable to expect, after the waste caused by denudation, that calcareous masses, gradually upheaved in an open sea, should retain such vast thicknesses? Or may not the limestones of the cretaceous and oolitic epochs, which attain in the Alps and Pyrenees a density of 3000 or 4000 feet, and are in great part made up of coralline and shelly matter, present us with a true geological counterpart of the recent coral reefs of equatorial seas? ”

“ It will be plainly seen that all these points of countries lean toward the Equatorial center of motion. The islands of Oceanica, strung out on the line of the Equator, also show the effect of the Earth’s revolution.
The Island of Australia is apparently a new production in embryo of a new continent in future connection with some of the large adjacent islands, and ultimately of most of the island groups of Oceanica. The same result is likely to follow with the Greater and Lesser Antilles.
The rivers are marked evidence of centrifugal force on both continents. ”

“ Rising up at the equator, it did not leave all its moisture with the cloud-ring, but, retaining a part, conveyed it through the cloud region, above the north-east trades, to this calm belt, where there was a descent and a crossing. The fact that these dry places are all within or on the equatorial side of this calm belt, while countries abounding with rains and well watered with running streams are to be found all along its polar side, is clearly indicative of a crossing. Upon no other supposition can we account for the barrenness on one side, the fertility on the other. ”

“ Vague and visionary as these speculations must seem to many, to others who are acquainted with the enormous glaciation to which America has been subjected they will appear to be based on substantial truths. The immense accumulation of ice over both poles, reaching far down into the temperate zones, in some meridians encroaching on the tropics, and in Equatorial America certainly all the land, lying 2000 feet above the level of the sea, supporting great glaciers, involve conditions which must have greatly drained the sea. ”

“ But the large masses of land, of uneven surface, which occur between the tropics, and the consequent inequalities of temperature, check the tendency of the intertropical atmosphere to a regular course, introduce derangement in its movements, so that it is only in the great open seas that the trade-winds are experienced. Still, it has been observed that, in some countries under and near the equator, constant easterly winds are found, which are no doubt identical in their cause with those that distinguish the equatorial regions of the ocean. ”

“ The theory that the difference of density caused by the difference of temperature between the polar seas and the equatorial oceans made under-currents to flow from the polar latitudes, and meet in the equatorial seas, can only be carried on in the Atlantic Ocean, and in a comparatively less perfect way in the Pacific Ocean, and not at all in the Indian Ocean. ”

“ The air of the equatorial belt, heated throughout the year, necessarily rises and creates an indraught from both north and south; but since the air thus flowing in has a lower rotary velocity than the earth’s surface at the Equator, it lags behind and so gives rise to northeast and southeast winds, respectively, between the two tropics and the equatorial belt. ”

“ Commencing at this parallel of 30°, therefore, in the North Pacific, and tracing thence the course of the north-east trade-winds, we shall find that they blow thence, and reach the region of equatorial calms near the Caroline Islands. Here they rise up; but, instead of pursuing the same course in the upper stratum of winds through the southern hemisphere, they, in consequence of the rotation of the earth (§ 207) , are made to take a south-east course. ”

“ When the rarefied equatorial air has travelled some thirty or forty degrees of latitude along the upper regions of the atmosphere towards the poles it becomes cooled, and is ready to descend again, between the latitudes of 30° and 60°, to supply the place of the lower air, drawn off towards the equator by the Trade-winds. ”

“ Where the inhabitants adapt their mode of life to the peculiarities of the climate, as is the case with the Dutch in the Malay Archipelago, they enjoy as robust health as in Europe, both in the case of persons born in Europe and of those who for generations have lived under a vertical sun.
Uniformity of the Equatorial Climate in all Parts of the Globe.—The description of the climatal phenomena of the equatorial zone here given, has been in great part drawn from long personal experience in South America and in the Malay Archipelago. ”

“ The vast and highest seas are nearer the equator than the poles; and there results from this observation, that the greatest inequalities of the globe are in the southern climate. These irregularities on the surface of the earth, are the causes of an infinity of extraordinary effects: for example, between the Indus and the Ganges, there is a large peninsula, which is divided through its middle, by a chain of high mountains called the Gate, and which extends from north to south, from the extremities of Mount Caucasus to Cape Comorin ”

“ Slichter has computed that in a change from a rotation period of 3.82 hours to the present one, the equatorial belt must shorten 1131 miles and the meridional circles lengthen 495 miles. If we take Heim’s estimate of the crust-shortening involved in forming the Alps—74 miles—as a standard, the 1131 miles of equatorial shortening would be sufficient for the formation of 15 mountain ranges of Alpine magnitude. If, as some geologists urge, the estimate of mountain folding is too great, the quotient would be still larger. ”

“ Just fancy that Providence had run the Equator through Europe, instead of through the Pacific, or wherever it is now. If the Equator happened to be located in the Old World, each of the kings we have seen, and more to be heard from, would be itching and grabbing for it, pouring out their subjects' blood like water (saving their own, of course) to get hold of the blamed thing. ”

“ It has been determined by the joint explorations of Speke, Grant, and myself, that the rainfall of the equatorial districts supplies two vast lakes, the Victoria and the Albert, of sufficient volume to support the Nile throughout its entire course of thirty degrees of latitude. Thus the parent stream, fed by never-failing reservoirs, supplied by the ten months' rainfall of the equator, rolls steadily on its way through arid sands and burning deserts until it reaches the Delta of Lower Egypt. ”

“ They have their birth where the moist, still air above the ocean in the region of the doldrums at the season when the equatorial belt of calms is farthest north, becomes highly heated and rises on account of the pressing in of cooler and heavier air from adjacent regions. The ascending column is at first carried 211 slowly westward, in obedience to the general flow of the atmosphere in the intertropical belt, and at the same time the currents coming in from opposite directions give the ascending air a rotary motion. ”

“ The calms which prevail northward of the equator depend upon the configuration of the African coast, which projects, at the distance of a few degrees from the Line, nearly 1,500,000 toises eastward; whilst the great distance at which one sails from the coast, after having crossed the equator, prevents the winds, generally prevalent in this part of the ocean, from being modified by the land breezes. ”

“ The fact is, there is not a single proper mountain-peak rising out of deep water at any great distance from the margins of the continents. All the numerous islands of the wide oceans are either coral reefs or the summits of volcanic cones.
Upon this shelf, and for the most part within two hundred miles of the coast, are deposited all of the materials torn from the land by the sea or brought down by rivers or glaciers, excepting the very finest, which currents may float somewhat farther out, and also excepting the rocks that icebergs carry away and drop in mid-ocean ”

“ Movements of elevation are also affecting Spitzbergen, Northern Siberia, North Greenland, the whole western borders of South America, Japan, the Kurile Islands, Asia Minor, and many other districts in the Mediterranean area, besides various islets in the great Pacific Ocean. The proofs of a slow movement of elevation are found in old sea-beaches and sea-caves, which now stand above the level of the sea. ”

“ In the bottom of the sea, while sand and mud and gravel were being deposited in successive layers in some portions of the ocean floor, in others great reefs of Eozoon were growing up in the manner of reefs of coral. If we can imagine the modern Pacific, with its volcanic islands and reefs of coral, to be deprived of all other forms of life, we should have a somewhat accurate picture of the Eozoic time as it appears to us now. ”

“ America, then in a south-easterly direction towards the coast of Africa, changing its direction again about Ascension Island, and running due south to Tristan d'Acunha. The ridge rises almost sheer about 9,000 feet from the ocean depths around it, while the Azores, St. Paul, Ascension, and Tristan d'Acunha are the peaks of this land which still remain above water. A line of 3,500 fathoms, or say, 21,000 feet, is required to sound the deepest parts of the Atlantic, but the higher parts of the ridge are only a hundred to a few hundred fathoms beneath the sea. ”

“ The Red Sea is out of account altogether; even the Mediterranean is too small to have great influence, and the Atlantic Ocean affects only a narrow belt along the west coast. Over regions so vast and so hot, every cloud is dispersed without moistening or fertilizing the parched ground. Only when we go much further south, near the equator, do the conditions change. ”

“ Every foot of dry land has undoubtedly, at one time or other, formed part of a sea-bottom, and we can hardly exclude the surfaces occupied by volcanic and fresh-water deposits, since, in many cases, if not in all, these rest upon a substratum of marine formations. At first sight, therefore, it seems a necessary inference that when the present continents were under water there must have been other continents situated where we now find the oceans, from which the sediments came to form the various deposits we now see. ”

“ If an object be set afloat in the ocean, as at the equator, it would, in the course of time, even though it should not be caught up by any of the known currents, find its way to the icy barriers about the poles, and again back among the tepid waters of the tropics. Such an object would illustrate the drift of the sea, and by its course would indicate the route which the surface-waters of the sea follow in their general channels of circulation to and fro between the equator and the poles. ”