Matthew Fontaine Maury, Lieutenant, U.S.N.

“ He makes it cut a bed for itself out of the soil, which is heavier than Admiral Smyth’s deep sea water, to the depth of more than two hundred feet below the top of the bar which obstructs its entrance into the sea. Could not the same power which scoops out this solid matter draw the brine up from the pool in the Mediterranean, and pass it out across the barrier in the Straits? The traction of locomotives on rail-roads and the force of that traction are well understood. Now have not currents in the deep sea power derived from some such force? ”

“ Heat the top of an iron plate, and the bottom becomes warm; but heat the top of a sheet of water, as in a pool or basin, and that at the bottom remains cool. The heat passes through iron by conduction, but to get through water it requires to be conveyed by a motion, which in fluids we call currents.
235. Therefore the study of the climates of the sea involves a knowledge of its currents, both cold and warm. They are the channels through which the waters circulate, and by means of which the harmonies of old ocean are preserved. ”

“ As new bars were successively formed seaward from the old, what dug up the sediment which formed the old, and lifted it up from where specific gravity had placed it, and carried it out to sea over a barrier not more than a few feet from the surface? ”

“ Suppose this under current from the Mediterranean to extend one hundred and sixty fathoms down, so as to chafe the barrier across the Straits. Upon the bottom of this current, then, there is a pressure of more than fifty atmospheres. Have we not here a source of power that would be capable of drawing up, by almost an insensibly slow motion, water from almost any depth? At any rate, it appears that the effect of currents by traction, or friction, or whatever force, does extend far below the level of their beds in shallow places. ”

“ If we except the tides, and the partial currents of the sea, such as those that may be created by the wind, we may lay it down as a rule (§ 34) that all the currents of the ocean owe their origin to difference of specific gravity between sea water at one place and sea water at another; for wherever there is such a difference, whether it be owing to difference of temperature or to difference of saltness, &c., it is a difference that disturbs equilibrium, and currents are the consequence. The heavier water goes toward the lighter, and the lighter whence the heavier comes ”

“ The reasoning of this celebrated geologist appears to be founded upon the assumption that when water, in consequence of its specific gravity, once sinks below the bottom of a current where it is shallowest, there is no force of traction in fluids, nor any other power, which can draw this heavy water up again. ”

“ To make it quite clear that the surface of the Red Sea is not a sea level, but is an inclined plane, suppose the channel of the Red Sea to have a perfectly smooth and level floor, with no water in it, and a wave ten feet high to enter the Straits of Bab-el-mandeb, and to flow up the channel at the rate of twenty miles a day for fifty days, losing daily, by evaporation, half an inch ”

“ The water in the Gut must be very deep; several of the commanders of our ships of war having attempted to sound it with the longest lines they could contrive, but could never find any bottom.” In 1828, Dr. Wollaston, in a paper before the Philosophical Society, stated that he found the specific gravity of a specimen of sea water, from a depth of six hundred and seventy fathoms, fifty miles within the Straits, to have a “density exceeding that of dis Mediterranean appears to have been a vexed question among the navigators and philosophers even of those times. ”

“ But instead of there being to the east of Alaska, as there is to the east of Greenland, an escape into the polar basin for these warm waters, the Pacific shore-line intervenes, and turns them down through a sort of North Sea along the western coast of the continent toward Mexico.
260. These contrasts show the principal points of resemblance and of difference between the currents and aqueous circulation in the two oceans. The ice-bearing currents of the North Atlantic are not repeated as to degree in the North Pacific, for there is no nursery for icebergs like the frozen ocean and its arms. ”

“ The experiments in deep-sea soundings have also throwfi much light upon the subject of under currents. There is reason to believe that they exist in all, or almost all parts of the deep sea, for never in any instance yet has the deep-sea line ceased to run out, even after the plummet had reached the bottom. If the line be held fast in the boat, it invariably parts, showing, when two or three miles of it are out, that the under-currents are sweeping against the bight of it with what seamen call a swigging force, that no sounding twine has yet proved strong enough to withstand. ”

“ It is not necessary to associate with oceanic currents the idea that they must of necessity, as on land, run from a higher to 12.5 a lower level. So far from this being the case, some currents of the sea actually run up hill, while others run on a level. The Gulf Stream is of the first class (§ 10) .
238. The currents which run from the Atlantic into the Mediterranean, and from the Indian Ocean into the Red Sea, are the reverse of this. ”

“ That the sea, in all parts, holds in solution the same kind of solid matter; that its waters in this place, where it never rains, are not salter than the strongest brine; and that in another place, where the rain is incessant, they are not entirely without salt, may be taken as evidence in proof of a system of currents or of circulation in the sea, by which its waters are shaken up and kept mixed together as though they were in a phial. Moreover, we may lay it down as a law in the system. of oceanic circulation, that every current in the sea has its counter current ”

“ A few of them report the current in their favor; most of them experience no current at all; but, now and then, some do find a current setting to the northward and westward, and operating against them at the rate of twenty miles a day.
The inter-tropical regions of the Atlantic, like those of the other oceans (§ 270) , abound with conflicting currents, which no researches yet have enabled the mariner to unravel so that he may at all times know where they are and tell how they run, in order that the navigator may be certain of their help when favorable, or sure of avoiding them if adverse. ”

“ Here the bottom of the current is probably a water-level, and the top an inclined plane, running down hill. Take the Red Sea current as an illustration. That sea lies, for the most part, within a rainless and riverless district. It may be compared to a long and narrow trough. Being in a rainless district, the evaporation from it is immense; none of the water thus taken up is returned to it either by rivers or rains. It is about one thousand miles long; it lies nearly north and south, and extends from latitude 13o to the parallel of 30o north ”

“ The fisheries of Japan are quite as extensive as those of Newfoundland, and the people of each country are indebted for their valuable supplies of excellent fish to the cold waters which the currents of the sea bring down to their shores. ”

“ Now water, while its capacities for heat are scarcely exceeded by those of any other substance, is one of the most complete of non-conductors. Heat does not permeate water as it does iron, for instance, or other good conductors. ”

“ Now we know the Red Sea is more than three thousand years old, and that it is not filled with salt; and the reason is, that as fast as the upper currents bring the salt in at the top, the under currents carry it out at the bottom.
252. MEDITERRANEAN CURRENTS.-With regard to an under current from the Mediterranean, we may begin by remarking that we know that there is a current always setting in at the surface from the Atlantic, and that this is a salt-water current, which carries an immense amount of salt into that sea. We know, rmoreover, that sea is not salting up ”

“ The counter currents, or those which return beneath the surface of the water, are also very remarkable; in some parts of the Archipelago they are at times so strong as to prevent the steering of the ship ”