Africa and the American Flag

by Andrew H. Foote

The Gulf of Guinea has in its own bosom a system of hurricanes and squalls, of which little is known but their existence and their danger. A description of them, of rather an old date, specifies as a fact that they begin by the appearance of a small mass of clouds in the zenith, which widens and extends till the canopy covers the horizon. Now if this were true of any given spot, it would indicate that the hurricane always began there. The appearance of a patch of cloud in the zenith could be true of only one place out of all those which the hurricane influenced. If it is meant that wherever the phenomenon originated, there a mass of cloud gradually formed in the zenith, this would be a most important particular in regard to the proximate cause of the phenomenon, for it would mark a rapid direction upwards of the atmosphere at that spot as the first observable incident of the series. That the movements produced would subsequently become whirling or circumvolant, is a mechanical necessity. But the force of the movement ought not to be strongest at the place where the mischief had its origin.

The squalls, with high towering clouds, which rise like a wall on the horizon, involve the same principles as to the formation of the vapor, and are easily explicable. They are not necessarily connected with circular hurricanes; but the principles of their formation may modify the intensity of the blasts in a circumvolant tornado. Since in the Gulf of Guinea they come from the eastward, it is to be inferred that they are ripples or undulations in an air current. In regard to all of this, it is necessary to speak doubtfully, for there is a great lack of accurate and detailed observation on these points.

Its position and physical characteristics give to this continent great influence over the rest of the earth. Africa, America, and Australia have nearly similar relations to the great oceans interposed respectively between them. Against the eastern sides of these regions are carried from the ocean those strange, furious whirlings in the shallow film of the earth’s atmosphere, which constitute hurricanes. It is evident that these oceans are mainly the channels in which the surface winds move, which are drawn from colder regions towards the equator. The shores are the banks of these air streams. The return currents above flow over every thing. They are thus prevalent in the interior, so that the climatic conditions there are different from those on the seaboard. These circumstances in the southern extra-tropical regions are accompanied by corresponding differences in the character of the vegetable world.

These winds are sometimes drawn aside across the coast line—constituting the Mediterranean sirocco, and the African harmattan. Vessels far off at sea, sailing to the northward, are covered or stained on the weather side of their rigging (that next to the African coast), with a fine light-yellow powder. A reddish-brown dust sometimes tinges the sails and rigging. An instance of this occurred on board the “Perry” on her outward bound passage, when five hundred miles from the African coast.

The science of Ehrenberg has been searching amid the microscopic organisms contained in these substances, for tokens of their origin. In the red material he finds forms betraying not an African, but an American source, presumed to be in the great plains of the Amazon and Orinoco. This suggests new views of the meteorology of the world; but the theories founded on it, are not clear of mechanical difficulties.

If we stand on almost any shore of the world as it exists at present, and consider the character of the land surface on the one hand, and of the ocean bottom on the other, we shall see that a very great difference in the nature of the beach line would be produced by a depression of the land towards the ocean, or by an elevation of it from the deep. The sea in its action on the bottom fills up hollows and obliterates precipices; but a land surface is worn into ravines and valleys. Hence a depression, so that the waters overflowed the land, would admit them into its recesses, and river courses, and winding gulleys—forming bays, islands, and secure harbors. Whereas elevation would bring up from the bottom its sand-banks and plains, forming an extent of slightly winding and unsheltered shore. The character of a coast will therefore depend very greatly upon its former history, before it became fixed. We have this contrast in the eastern and western sides of the Adriatic, or in the western and eastern sides of the British islands. These circumstances are to some degree controlled by the effects of partial volcanoes, or of powerful winds and currents. But on the whole, it may generally be inferred that a long unbroken shore indicates that the last change on the land level was one of elevation; while a coast penetrated, broken, and defended by islands has received its conformation from being stopped in the process of subsiding.

The coast of Africa has over almost its whole circuit, that unbroken or slightly indented outline which would arise from upheaval. The only conspicuous exception to this, is in the eastern region, neighboring on the Mozambique Channel, where the Portuguese and the Arab possess the advantage, so rare in Africa, of having at their command convenient and sheltered harbors. There are centres of partial volcanic agency in the islands of the Atlantic, north of the equator, and in the distant spots settled by Europeans outside of Madagascar; but this action has not, as in the Mediterranean or Archipelago, modified the character of the continental shore. It is not known that there exists any active volcano on the continent.

Africa, therefore, if it could be seen on a great model of the world, would offer little, comparatively, that was varied in outline or in aspect. There would be great tawny deserts, with scanty specks of dusky green, or threads of sombre verdure tracing out its scant and temporary streams. There would be forests concealing or embracing the mouths of rivers, with brown mountains here and there penetrating through them, but rarely presenting a lofty wall to the sea. Interior plains would show some glittering lakes, begirt by the jungle which they create. But it is a land nearly devoid of winter, either temporary or permanent. Only one or two specks, near the mouth of the Red Sea, and a short beaded line of the chain of Atlas, would throw abroad the silver splendor of perpetual snow. It is the great want of Africa, that so few mountains have on their heads these supplies for summer streams.

The sea-shore is generally low, except as influenced by Atlas, or the Abyssinian ranges, or the mountains of the southern extremity. There is, not uncommonly, a flat swampy plain, bordering on the sea, where the rivers push out their deltas, or form lagoons by their conflict with the fierce surge upon the shore. Generally at varying distances, there occur falls or rapids in the great rivers, showing that they are descending from interior plains of considerable elevation. The central regions seem, in fact, to form two, or perhaps three great elevated plateaux or terraced plains, having waters collected in their depressions, and joined by necks; such as are the prairies of Illinois, between the St. Lawrence and the Mississippi, or the llanos of South America between its great rivers. The southern one of these African plains approaches close to the Atlantic near the Orange River. Starting there at the height of three thousand feet, it proceeds round the sources of the river, and spreads centrally along by the lately visited, but long known lakes north of the tropic. The equinoctial portion of it is probably drained by the Zambeze and the Zaire, flowing in opposite directions. It appears to be continuous as a neck westward of Kilmandjaro, the probable source of the Nile; till it spreads out into the vast space extending from Cape Verde to Suez, including in it the Niger and the Nile, the great desert, and the collections of waters forming Lake Tzad, and such others as there may be towards Fitre.

The mountains inclosing these spaces form a nearly continuous wall along the eastern side of Africa. The snows of Atlas form small streams, trickling down north and south; and, in the latter case, struggling almost in vain with the tropical heats, in short courses, towards the Desert of Sahara.