Seawater

“ But on islands composed as many of those on our Southern coasts are, of pure sand and of very small elevation, and hence with no raised reservoir to supply springs, the fact that pure fresh water may be obtained in large quantities by digging, is a mystery even to many well-informed people, although the explanation is very simple. To say that the "sea-water filters through the sand into these wells and becomes as sweet and pure as spring-water," is simply to display profound ignorance of chemistry and facts. ”

“ The momentum of the tide running up the centre of the river is in excess of that along the banks, so that the current changes near the shore before it does in the middle, and, as the sea water is of greater specific gravity than the fresh, weighing 64 lb per cubic foot against 62-1/2 lb, it flows up the bed of the river at the commencement of the tide, while the fresh water on the surface is running in the opposite direction. ”

“ All these isles are connected, and include a lagoon in the middle, which is full of the finest fish; and sometimes there is an opening, admitting a boat, or canoe, in the reef, but I never saw or heard of an opening that would admit a ship. The reef, or the first origin of these cells, is formed by the animalcules inhabiting the lithophytes. They raise their habitation within a little of the surface of the sea, which gradually throws shells, weeds, sand, small bits of corals, and other things, on the tops of these coral rocks, and at last fairly raises them above water ”

“ It is a basin among the ledges, filled with quiet sea-water left by the retreat of the tide, half-floored with sandy mud, and its edges fringed with feathery seaweeds, corallines, and hydroids. Here is a capital home for the little folk of the sea, where there is always fresh clear water, but where only a part of the time do the surges pound, and then never with full force; furthermore, a wall of rocks protects the nook, and enemies can rarely enter to destroy the peaceful society. ”

“ Like such a great river as that he knew so well and frequented all his days, his life flowed steadily and strongly, the brimming stream augmenting always, deepening and widening, the heavier current moving, at the end, more slowly but not through slackening of power, until, at the last turn, the majestic estuary opens and broadens, as, with no hurry of fretting waves, no straining through silted sandbanks, undiminished, the mighty mass of waters mingles with the sea. ”

“ Such a salt-water saucer of fresh water is maintained full to overflowing by the rainfall, and owing to the frictional resistance of the sand and to capillary action and the fact that a given column of fresh water is balanced by a shorter column of sea water, the fresh water never sinks to the mean sea-level unless artificially abstracted. ”

“ But there are a good many others which you can find very easily indeed. All that you have to do is to wait until the tide has gone out, and then to go down and look into the pools which are left among the rocks. There you are almost sure to see a number of shadowy forms darting to and fro through the water. Some of these, most likely, will be shrimps and prawns, which are always very common in the rock-pools; but the others will be tiny fishes. And even if you have not got a net you can often catch them quite easily. ”

“ The tidal movement of the ocean, deep-sea currents, and the agitation of inland waters by the wind, lift up the sands strewn over the bottom by diluvial streams or sent down by mountain torrents, and throw them up on dry land, or deposit them in sheltered bays and nooks of the coast—for the flowing is stronger than the ebbing tide, the affluent than the refluent wave. ”

“ You merely go out to the reef at low tide, collect as many of the myriad white coral fronds from the rock pools as you can comfortably carry in a reed basket, and take it on your head up to the factory. ”

“ We have also pools, of which some do strain fresh water out of salt; and others by art do turn fresh water into salt. We have also some rocks in the midst of the sea, and some bays upon the shore, for some works wherein is required the air and vapour of the sea. We have likewise violent streams and cataracts, which serve us for many motions: and likewise engines for multiplying and enforcing of winds, to set also on going divers motions. ”

“ The fresh-water forms are specifically distinct from those incidental to salt or brackish water,—fresh-water species, however, are sometimes carried some distance into the sea by the force of the current, and in tidal rivers marine forms are carried up by the force of the tide. ”

“ The differences in level which determine circulation are much more trivial. Every stream which pours fresh water into the sea tends to raise the level of the water where it enters. The waters brought to the ocean by the Amazon, the Mississippi, and other great rivers would appreciably change the level of the sea at their debouchures, if the excess did not promptly flow away. The ready mobility of the water, however, prevents its accumulation, and the discharge of every stream generates widespread movement. ”

“ This wave has first to overcome the water flowing down the river, which is acting in opposition to it, and in so doing causes a banking up of the water to such a height that the inclination of the surface is reversed to an extent sufficient to cause a tidal current to run up the river. The momentum acquired by the water passing up-stream carries it to a higher level towards the head of the river than at the mouth, and, similarly, in returning, the water flowing down the river gains sufficient impetus to scoop out the water at the mouth and form a low water below that in the sea adjoining. ”

“ On your right hand, the river comes roaring forward with all the agitation of a tempestuous ocean, recoiling in waves and whirlpools, as if determined to resist the impulse which is forcing it downward to the gulf. When within a few yards, and apparently at the moment of sweeping away, it plunges headlong into what seems a bottomless pit, for the vapor is so thick at the foot of the precipice that the torrent is completely lost to the view. ”

“ The deposits of the ocean no longer tenaciously adhere, but remain in a loose state, and form what is termed by mariners a key upon the summit of the reef; while the sea, by throwing up sand and mud on the top of these animal rocks, progressively raises them above its level. ”

“ From the great number of freshwater forms which we see at this present day acclimatised in, gradually acclimatising themselves in, or periodically or sporadically migrating into, the sea, we must conclude that, under certain circumstances, salt water may cease to be an impassable barrier at some period of the existence of freshwater species, and that many of them have passed from one river through salt water into another. ”

“ The tide flows up the river many miles past the waterworks, carrying up with it the filth from the sewers. The supply of water was, to be sure, obtained when the tide was down, but as the banks of the river are clothed with sedges in many parts, and its bottom deep with mud, the water can never be free from sewage. ”

“ Still, the constituents of sea water from the Mediterranean and of sea water from the Red Sea are quite the same. But the waters of the Dead Sea have no connection with those of the ocean; they are cut off from its channels of circulation, and are therefore quite different, as to their components, from any arm, frith, or gulf of the broad ocean. Its inhabitants are also different from those of the high seas.
297. “The solid constituents of sea water amount to about 32 per cent. ”

“ After a time the salt water becomes diffused in the fresh, so that the density of the water in a river decreases as the distance from the sea increases. The disposal of sewage discharged into a river is due primarily to the mixing action which is taking place; inasmuch as the tidal current which is the transporting agent rarely flows more rapidly than from two to four miles per hour, or, say, twelve to fifteen miles per tide. ”

“ The muddy waters of rivers seem indisposed to mingle with the salt waters of the sea, or rather the salt waters of the ocean turn the muddy waters on the one side or the other of the mouth of rivers, until they have deposited their mud, and then the clear new water cordially joins the older, briny ocean. ”

“ This drains off from the surface, forming rills, which collect as they descend, by their own weight, into the lowest channels of the ground, and form into streams and rivers, and back into the sea comes the water which the air had taken away, with this difference, that it is free from salt and fit for the many uses to which fresh water alone can be applied; when the vapour rises from the sea, none of the saline matters rise with it, for, although the water is volatile, yet they are not, and this is the whole source of fresh water. ”

“ And in the summer you might imagine that the upper Thames had been transported to Norfolk, so full are the Broads and [Pg 5] rivers of picnicking parties. Why, then, not live in a houseboat on sea water? Sea water is a great purifier. No fear that it will become stagnant or rank. Its transmuting process turns everything to purity. Take an odd proof. Even rubbish or paper in sea water is not an offence as it is in fresh water. Hurried along on the tide, it bears a relation to the great business of ships; but in fresh water it reminds one of disagreeable people, careless of all the amenities. ”

“ And the submarine rocks or shores of these new formations of land became covered with aquatic vegetables, on which various species of shell-fish and common fishes found their nourishment. The fluids of the globe in cooling deposited a large quantity of the materials they held in solution, and these deposits agglutinating together the sand, the immense masses of coral rocks, and some of the remains of the shells and fishes found round the shores of the primitive lands, produced the first order of secondary rocks. ”

“ The result will be that the particles will travel a little farther out from the shore each time it is swung to and fro in the alternating movement of the tide.
The effect of tidal movement in nurturing marine life is very great. It aids the animals fixed on the bottoms of the deep seas to obtain their provision of food and their share of oxygen by drawing the water by their bodies. All regions which are visited by strong tides commonly have in the shallows near the shores a thick growth of seaweed which furnishes an ample provision of food for the fishes and other forms of animal life. ”

“ Very little thought or attention is paid to the insidious changes produced by water on the Earth’s surface.
Not a day passes, or has gone by, but that a large quantity of material is transferred from one locality to another. Every shower carries from some higher point to a lower, and a certain amount of drift goes toward some ocean. Small streams contribute to the larger ones, and all lead to the great ocean reservoirs. In going across our country many important evidences are to be seen of the immensity of work accomplished by water, in the removal of vast areas and depths of land. ”

“ It must be understood that where real sea water can be easily obtained, as at spots near the coast, it is undoubtedly the best, though, in some respects, the artificial preparation is preferable, because less liable to certain eccentric changes of constitution, which will fall under our attention further on. Sea-water contains the spores of plants, and the germs of many forms of animal life which may have development in the tank, and when these births occur, it is a special gratification to the possessor. ”

“ When a river enters the sea it soon loses its individuality; it becomes merged in the body of the ocean, where it loses its current, and where therefore it has no power to keep in suspension the sediment which it had brought down from the higher lands. ”

“ When the tide begins to flow up the river there may be a low-level salt water current moving landward and a high-level fresh water current moving seaward, but this is quite a temporary state of affairs. The surface slope is landward, and the water moving seaward is not moving in obedience to the surface slope. ”

“ The course of water flowing underground is not strictly analogous to that of rivers on the surface, there being, in the one case, a constant descent from a higher to a lower level from the source of the stream to the sea; whereas, in the other, the water may at one time sink far below the level of the ocean, and afterwards rise again high above it. ”

“ The quantity of water, consequently, that is required, and is continually supplied from the ocean by the process of evaporation, both for the support and reanimation of nature, must be immense, and may of course be supposed permanently to absorb a very large proportion of the surplus waters of these circumscribed seas, while the remaining portion of surplus water, if not thus wholly accounted for, may be distributed over the general expanse of the ocean. ”

“ Stand on the bank of an estuary or river up and down which a great tidal current ebbs and flows; you [42] will see the water copiously charged with sediment which the tide is bearing along. Engineers are well aware of the potency of the tide as a vehicle for transporting stupendous quantities of sand or mud. A sand-bank impedes the navigation of a river ”