How grand is the ever-moving ocean! how majestic its voice, how terrible its anger! how beautiful every colour that is reflected from its dancing spray, and how balmy the air which is wafted from its bosom to refresh the heated earth, which, under the glare of a summer's sun, seems parched with thirst. How refreshing to the senses is the change from the dry heated grass on a midsummer day—from the dusty roads—from the smoke begrimed town, smelling of dirt, and heated by the reflection of the sun's rays from bricks and stones till it becomes a furnace—from the close dark habitations of the city—from the rattle, excitement, and continual noise of vehicles and human voices—from the corroding cares and depressing influences attending the fierce "battle of life"—to the cool and gentle breeze, "the wide o'er-arching canopy of heaven," the murmur and ripple of the sea, to the clear and exhilarating air, free from soot and laden with the odour of the ocean.—Oh what a desirable change! all human nature seems to own it, and hasten to the shores of the great watery world, that they may contemplate one of the greatest and grandest of God's works with admiration and thankfulness, and be re-animated by its health-giving powers.

It is a wonderful sight, and one which fills our minds with reflection; here we see many of the laws of nature exemplified on a great scale. The laws of gravity keep the surface of the ocean perfectly spherical as a whole, while those of equilibrium keep it in constant and ever-varying motion, the laws of attraction produce the tides, and those of reflection and refraction cause its surface to assume all sorts of colours and tints.

The ocean is full of life, both vegetative and animal; myriads of both classes have their natural habitation in the sea, and the shore is often, after a gale, strewed with curiosities well worth the contemplation of those who devote their minds to thought. How many varieties of sea-weed have you gathered? perhaps twenty; not three of them are sea-weed at all! they are living animals, either zoophytes or molluscs, every branch of that "flustra" contains a thousand living beings, every spray of "sertularia" as many more, that other piece is the "bugula neretina" and also owns a colony of animals: the next is indeed a member of the vegetable kingdom, its beautiful crimson colour makes it a conspicuous object, and there are many specimens of the same plant, but of all shades of red, crimson, and purple, it is the "plocamium coccineum." And thus it is with every object we view, a knowledge of it brings us to respect and admire it more and more as that knowledge increases, and none more so than some of the productions of the sea. It is here we find specimens of the star-fish, the sea-urchin, and other radiata. Shells of all kinds—both living and dead—belonging to the various tribes of mollusca; crabs, shrimps, and other crustaceans, besides the endless varieties of pebbles and other specimens of worn-down rock, the effects of constant attrition.

If we turn from the shore and gaze upon the horizon, what a marvellous object it is—ever receding as we recede, ever rising as we rise, and never nearer nor farther away. This rising of the horizon, so as to be always opposite to our eyes, is because the higher we are up the more we see. On looking at the horizon we do not look on a perfect level, (if we did, being above it, of course we could not see it at all) but the depression of the line of vision is so slight as to be quite unable to be appreciated; yet, small as it is, it enables us to see a considerable space of the ocean, and the higher we rise—at the same angle—the more we see. The edge of the horizon also appears curved, being higher in front of us than on either side. This is only so in appearance, for if any one were to place a piece of string (stretched tightly between the hands) before his eyes, and bring it up till it is on a level with the horizon, he would soon see that the string and the horizon were both perfectly straight and exactly corresponding with each other.

From the horizon we turn round and look at the chalk cliffs, those white walls from which our native isle has received the name of "Albion." How were they produced? by the constant lashing of the restless waters, which are constantly wearing them away; but they are beautiful objects, full of marvels and records of bygone ages, when their tops were at the bottom of the deep seas.

The sea is a general name given to all the greater collections of water throughout the world, although, in a restricted sense, it is applied to those tracts of water of a secondary size, as the Black Sea, the Baltic, and the Mediterranean, the term "ocean" being applied to the larger tracts of water, as the Atlantic Ocean, the Pacific Ocean, &c. All the great oceans and seas unite, and, in reality, form one great world of waters, spread out and covering all the lower parts of the earth, the term "lake" being applied to collections of water surrounded by land, although the Caspian Sea retains the name of sea, and some of the great lakes of America may well deserve such a name.

The waters of the sea fill up all the lower parts of the earth, so that, almost without exception, the land is higher than the water, and as the land in some places rises but a few feet, and in others as many thousands, so, beneath the sea, the land sinks in many places but a few feet, and in others perhaps as many thousands as it is known to rise above it. The sea always maintains the same general level, although in past ages the land has risen and fallen, sometimes in one place and sometimes in another; indeed, the same process is taking place every day, but in so slow a manner that centuries are required to make any great alteration; while some tracts of land are being encroached on by the action of the waves, others are being added to and elevated by accumulations of mud and sand, or raised by the action of earthquakes and volcanoes, which throw up under the sea, as well as on the land, vast quantities of melted earth or lava, forming strata known to geologists as basalt, tufa, &c., or eject showers of ashes and dust in such prodigious quantities as to cover many hundred square miles of the earth's surface. It was by one of these showers of ashes from Vesuvius that the cities of Herculaneum and Pompeii were buried. So that, as a whole, although the sea is continually altering slowly its position, yet it pretty equally maintains the same elevation. At first thought it may be supposed that the rivers constantly flowing into the sea would alter its level, for some are so large that millions of tons of water are brought by them into the sea every hour, and there are thousands of rivers and rills which, night and day, pour in their tribute of waters; but God has wisely and kindly arranged these things (like all others) so that they shall afford us innumerable comforts, and yet not raise up the sea so that it shall cover the land, for it requires but a moment's consideration to be convinced that all this water which flows into the sea must first have been abstracted from it, and it is in this way—when the winds blow over the sea, they absorb or take up a certain quantity of the vapour which continually rises from it; for air absorbs a certain quantity, and a certain quantity only, of the vapour of water; but this quantity is determined by certain circumstances, for instance, the warmer the air, the more it will absorb, the less the pressure on the air, the more it will absorb, and the drier the air, the more it will absorb, that is, the less moisture it has already got, the more will be required to make up that quantity which the other circumstances permit it to contain. Now, what takes place if a warm, dry, light current of wind blows over the sea, landward? Why, all the vapour given off by the sea, to the amount of millions of gallons, is absorbed and carried inland by the wind or current of the air, and this continues onward, laden with moisture, until it meets with one of the several circumstances which shall cause it to be incapable of holding the quantity of moisture which it has already got; for instance, it meets with another current of air colder than itself, these mingle, the vapour of water is condensed by the cold, and a cloud is formed. This consists of minute particles of water suspended in—not absorbed by—air; these particles gradually collect, and down falls the rain on to the earth. 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. It is distilled in the great laboratory of Nature, and gives nourishment to all the living beings who dwell on the land and in the rivers and lakes; or the rain may sink into the earth and be carried for miles and miles under ground, running through some porous stratum, such as gravel, until it flows out in the form of a spring, bubbling up amongst flowers and weeds, and forming the source of some river, which receiving the rain and all the springs in the country through which it flows, finds its way back into the ocean at last.

This is the way in which all rivers and streams are formed. An enormous extent of land thus drained gives rise to thousands of rills, which collect into streams of goodly size, meandering through valleys and pouring their tribute of waters into a main stream, which at last accumulates by additions to its course, and becomes one of those great water-courses which form the highway through a continent. The Amazon, Hoang-Ho, Ganges, Nile, Danube, and Volga, may be cited as some of the greatest water- courses and highways of civilisation. These great rivers are navigable for large ships, even for many hundreds of miles, and it is most fortunate that this navigation is so seldom impeded by falls; for these, although among the grandest and most beautiful objects of nature, yet put a stop to the navigation of a river which would otherwise be passable for hundreds of miles further. Rivers which run through districts subject to periodical rains, or those whose sources lead from mountain slopes where vast quantities of snow are deposited in winter which melts on the approach of summer, are at such seasons of the year suddenly augmented, and generally overflow the banks and inundate the country for miles. This is in many cases a very great misfortune, as it spoils the land, reducing it to a swamp, but not in every case; the overflowing of the Nile brings down with it a great quantity of fertilising vegetable matter, and serves to manure the whole district, for the soil being extremely porous and the heat great, the moisture is soon got rid of, and hence it was a custom of the Egyptians to celebrate the rising of the Nile by feasts and ceremonies.

Lakes are formed in the same way as rivers, but, being surrounded by high land, have no outlet for the waters so that they may flow back into the sea. If a lake were about to be formed it would be in this way—the rain descending on the surrounding high lands would run in rills to the lowest part, and there collect, forming a pool which would gradually increase in size as the water flowed into it, this increase continuing until the surface became so large that the evaporation from it exactly equalled the supply, it would then extend no further, but remain a permanent lake or inland sea, giving off vapour to refresh the surrounding country, and again receiving it back by streams and rivers, as does the ocean.

There is scarcely a spot known on the surface of the earth, which does not show strong evidence of having, at some former period, been the bed or bottom of some sea or lake. Some of these evidences may be seen in the strata or layers of earth forming the sides of the cliffs which abut on the sea-shore, and which could not have been produced by any other agency; these strata contain so many marine shells and other matters peculiar to the sea, that the fact does not admit of doubt that they were there produced. These same strata are met with throughout the land; in sinking wells and mines, the same strata are cut through, and have a known and uniform succession, with but few exceptions; the cliffs, however, are the most convenient places to see these strata. That the same process of alteration in the position of the water and land is still going forward, is shown by many evidences, such as towns which were once on the sea-shore, being now some distance from it, as the City of Norwich, and in other cases the reverse. The chalk cliffs at Dover, Ramsgate, &c., show the action of the sea in the corroded state they present, and slips or falls of great masses which have been undermined by the sea, are frequently occurring.

The ancient town of Ravenspurn, at which Henry IV. landed, has entirely disappeared, and others, recorded to have been situated on the shore, have now only their names left. The parts of the shore most rapidly corroded by the sea, are those composed of sand, chalk, and clay, while those composed of the harder kinds of sandstone or of granite, have been but little wasted away, so that they project and form the headlands, while in many cases deposits of mud have extended them. There are many other causes which determine the elevation or depression of the land, besides the action of the sea and earthquakes, such as winds, frosts, &c.

The slightest movement of the air communicates motion to the surface of such a great sheet of water as the sea, and this motion is gradually increased till one ripple meets another, and the power of both goes to form the next, so that they acquire a very considerable size; when a gale of wind blows, the rolling of the waves far out at sea becomes terrific, and they rise like mountains, chasing one another over the wide ocean. But sailors rather like a smart breeze, and more especially did they a few years ago, when the wind was all they had to depend upon for onward progress. In those days a calm which would sometimes last for weeks together was to them most fearful, for it was often a source of great distress and privation, especially if short of provisions; the sea would then look like a great pool of stagnant water covered on the surface with sea-weed and animalculÆ, and fearful it must have been when food was failing, and no hope of progressing but the springing-up of a wind. But, in these days, with the assistance of steam, a calm is the very time in which most progress is made, and there is no doubt but a time will come when it will be matter of wonder that men could ever have trusted to so uncertain an element as the wind; yet, if it were not for the winds, currents, and tides, the sea could not maintain its state of purity, for its saltness is not sufficient to prevent the growth of fungi and all sorts of animalculÆ, which, from their decay, would produce noxious gases and be most injurious to animal life. Its constant motion alone prevents this, and the spores and germs are tossed about until destroyed and eaten up by the inhabitants of the deep who devour every kind of organic matter which is deposited in the sea, and thus it is that the waters of the ocean are so bright and clear that an object can be seen at a considerable depth.

That the constant currents of the sea prevent the formation and growth of sea-weed, is clearly shown by the great "Sargasso Sea," or tract of weed (Fucus natans), called the Gulf-weed. This great tract embraces thousands of square miles, and is situated in the very middle of the Atlantic Ocean, where there are but few currents; but surrounding it is the Gulf-Stream, an enormous current of water running at a regular rate of four or five miles an hour. This Gulf-Stream is supposed to be caused by the same laws and influences which determine the trade-winds, namely, a constant rarefaction of the water at the tropical parts of the earth, and a corresponding condensation at the Arctic portions, for warm water is much lighter than cold, and when the waters of the tropical regions become lighter the heavier waters of the cold regions pressing down more forcibly tend to raise them above their proper level; they therefore flow towards those very parts which have sunk down by their contraction, and a constant current takes place—this current is the Gulf-Stream. It runs from the Gulf of Mexico northwards towards Newfoundland, turning by Iceland towards the British Isles, by France and Spain, onwards to the coasts of Africa and South America, the West Indies, and again to the Gulf of Mexico, although the return current does not go by the name of Gulf-Stream. This great stream of water warmed by the tropical sun serves the same two purposes described under the section "Air" as being fulfilled by the trade-winds, namely, a circulation and distribution of the superfluous heat of the equatorial regions, warming the northern countries and cooling by the return of under-currents those in the tropics. The fogs of Newfoundland are caused by the great current of warm water entering the cold region and carrying with them surface-currents of moist air, which the cold condenses into fog, just as the breath is visible in a cold atmosphere. England owes its moist and mild climate to the same cause.

The sand which lies upon the sea-shore is produced by the action of the waves constantly dashing against the earth and rocks of the coast, and is mostly composed of what chemists call "silex," or silica, which is a chief constituent of most rocks and earths; these, being worn down by the action of the waters, form sand. The fragments of these rocks (especially granite) and those which contain silica in the form of minute crystals, are soon rolled and rubbed together until they are ground to powder, but it is doubtful whether any sand exists at the bottom of the deep seas far from shore, as the waters there lie—and must have laid—perfectly quiet ever since they were seas, for the greatest storm that ever rages does not affect the tranquility of the sea more than a few fathoms beneath its surface, so that a stone dropped in the middle of the Atlantic Ocean, could be picked up after a hundred years exactly where it fell, were it possible for any to find out the spot and descend; but the bottom of some deep seas, as in the antarctic regions and the north Atlantic Ocean (as the soundings between Ireland and America have lately shown), is covered to an unknown depth with what had been supposed to be sand, but which is not sand at all, but a wonderful collection of minute shells and coralines, which to the unassisted eye have the appearance of sand. They are the silicious shells and coverings of minute vegetables and animals, these creatures, being coated with silica (a substance indestructible by age and the action of water), fall to the bottom of the sea and there accumulate in such countless myriads that they form this fine substance, long mistaken for sand, but between which, in reality, there is a marked distinction, the one being formed by the disintegration and grinding-up of rocks, the other the product of organic life; this, when it has accumulated for ages, will, in all probability, form some island or part of a continent, and be the site perhaps of some magnificent city, reared upon a foundation of these minute wonders of the deep, whose skeletons will have become consolidated into a hard and compact stone, of which its houses and churches will, in all probability, be built.

This is not imagination, as such occurrences have really taken place—all our chalk cliffs and downs constitute part of an immense stratum. Now, every grain of this chalk contains and is made up of thousands of minute shells and corals. These chalk downs were once the bed of some ocean which, in all probability, was filled up by their remains.

What are the railroads and works of men's hands compared with this? Of this chalk (hardened by pressure into limestone) most of our public buildings are constructed, or (changed by pressure and heat into marble) our statues of great men have been carved. What a mockery to choose marble as the medium of rendering our heroes immortal—itself the very type of mortality, being formed by the death of millions of creatures.

In Dr. Carpenter's work on the microscope occurs the following:—

"Thus, when we meet with an extensive stratum of fossilised DiatomaceÆ, in what is now dry land, we can entertain no doubt that this silicious deposit originally accumulated either at the bottom of a fresh-water lake or beneath the waters of the ocean, just as some deposits are formed at the present time, by the production and death of successive generations of these bodies, whose indestructible casings accumulate in the lapse of ages, so as to form layers, whose thickness is only limited by the time during which this process has been in action.

"In like manner, when we meet with a limestone rock entirely composed of the calcareous shells of Foraminifera—some of them entire, others broken up into minute particles—we interpret the phenomenon by the fact that the dredgings obtained from certain parts of the ocean-bottom, consist almost entirely of remains of existing Foraminifera, in which entire shells—the animals of which may be yet alive—are mingled with the debris of others that have been reduced by the action of the waves to a fragmentary state.

"Now, in the fine white mud which is brought up from almost every part of the sea-bottom of the Levant, where it forms a stratum that is continually undergoing a slow but steady increase in thickness, the microscopic researches of Professor Williamson have shown that not only are there multitudes of minute remains of living organisms, both animal and vegetable, but that it is entirely or almost wholly composed of such remains."

The water of the sea is everywhere salt, except at the mouths of great rivers, where the quantity of fresh water displaces that which properly belongs to the sea. The cause of its saltness is the solution of a natural mineral (chloride of sodium) which exists in the earth in great abundance in layers of a crystalline structure, and as this chloride of sodium (common salt) is soluble in water, of course it is all dissolved by the water in whatever situation they may come into contact with each other. The composition of sea-water differs slightly in different parts of the earth, the southern seas being slightly more salt than the northern. As a general rule, about five per cent. of solid matter is contained in sea-water, of this rather more than half (5.7) is chloride of sodium; the greater part of the other half consists of different salts of magnesia, and this is the whole source of the medicines known as Epsom salts and magnesia, the former being the sulphate and the latter the carbonate of magnesia. Iodine, another article used in medicine and photography, is also extracted from sea-water, which however contains but a very minute portion, too small to be detected as a general rule, but extracted by burning certain sea-weeds, in the ashes of which it is found in sufficient quantity to be separated.

Although the sea as a whole keeps its level, yet in various parts it is constantly rising and sinking, sometimes at one place and sometimes at another; these risings and fallings are called tides, and are caused by the joint action of the sun and moon, that is, by their attraction, acting at different distances. First it must be observed (as is well known) attraction varies inversely as the square of the distance, that is, if the moon were twice as far off, her attraction of the earth would be one-fourth of what it now is, if three times as far off, one-ninth, and so on.

The moon's average distance from the centre of the earth (A to C, in the diagram) is about 240,000 miles, or about 60 times the earth's radius (B C), which is a little under 4000 miles, consequently if the distance from the moon to the centre of the earth (A C) be expressed by 60, the distance to the nearest surface (A B) will be 59, and the farthest surface (A D) 61. The moon will attract the point B with a force of 1/59² or 1/3481, the point C with the force of 1/60² or 1/3600, and the point D with the force of 1/61² or 1/3721. Now as the force at C is greater than at D, the earth itself will be pulled away from the water at D, and leaving it a little behind, will produce a high tide there, this tide is known as the "inferior tide" (2). Again as the force at B is greater than at C, the water at B will be pulled away from the earth and produce a still higher tide, called the "superior tide" (1), or that which takes place when the moon is due south. This heaping-up of the waters by the moon, to the height of 4½ feet (on an average) causes corresponding depressions to the same depth in those parts of the earth which are situated between the raised parts, making a difference between high and low-water of nine feet due to the moon; precisely the same effects are produced by the sun, but though his attractive power is so much greater than the moon's, his distance is also so much greater, that the heap of water he can raise is somewhat less than 2 feet, and makes therefore less than 4 feet difference between high and low-water, due to the sun. When the sun and moon are both on the same side, or on opposite sides of the earth (as at new or full moon), then the attraction of both act together and produce "spring tides," with a difference of 13 feet; at first and last quarter the sun and moon oppose each other, acting in cross directions, and the difference is then only 5 feet. But these effects could only take place in the wide open space of an ocean, and when other forces do not interfere, such as obstruction to the tide-waves by land, &c.

Inland seas (as large as the Mediterranean even) have but very little tide, while pinched-up rivers may have a great rush of tide, as at Bristol, where it rises to 45 feet sometimes, and at Anapolis in Nova Scotia, to so much as 120 feet! Wind will also accelerate or retard both the speed and height of the tides. London receives a much greater tide than its due, for the tidal-wave being interrupted by Ireland and England, rolls up the western coast (taking a northerly direction) with such force as to swing round the Shetlands and all down the eastern coast of Great Britain. The direct Atlantic wave also, when split by our island, rolls along the south coast from Land's-End to Dover, rushes through the "Straits," and meets the backward wave which has been travelling round by Scotland (as before mentioned), the two then pour into the Thames and give an otherwise quiet river a high and useful tide; so that London receives two tides, the southern one nearly 10 hours after Cornwall, and the roundabout one not till nearly 23 hours after it first reaches England.

The waters are the great highway throughout the whole world, and what an easy transit it has formed to those nations sufficiently civilised to require a further knowledge of the world, and thence procure for themselves luxuries not obtainable at home—at the same time, spreading civilisation wherever they go!

If the oceans, instead of forming one great concourse of waters, had existed in the form of inland seas or great lakes, the great chains of mountains, deserts, and uninhabited tracts of earth, would, in some cases, have formed impassable barriers, whilst in other parts civilisation would have been impeded from the easy access of the more savage tribes, who would have despoiled the more fortunate by inroads amongst them, mingling with or exterminating them, and checking the onward progress of civilisation. And this has always existed where great tracts of land are, which are the last parts of the world to be civilised, and in many parts remain as rude as they were thousands of years ago. All this is owing to the good and wise arrangement of water and land, and is an instance of the care and foreknowledge of God, who has provided for the onward progress of that creature to whom alone such a progress has been allotted; but as they now exist the oceans form impenetrable barriers to the savage, so as to restrict his brute force and uncultivated habits spreading, while they form easily-traversed highways to the more civilised nations, enabling them to spread their civilisation without contamination to themselves, but to the advancement of others.

The oceans are now navigated by thousands of vessels engaged in mercantile objects, and it is perfectly astonishing with what rapidity and safety these great tracts of water are crossed.

In one of Chambers's "Papers for the People," called "Ocean Routes," is the following, speaking of the perfecting of the steam-vessel:—

"The regularity, speed, and safety with which the voyages of these vessels were made, soon pointed them out as the best conveyance both for passengers and the mails.

"In 1821 they were employed on the latter service between Dublin and Holyhead, and between Calais and Dover; and now, with few exceptions, all the channel and ocean-work of the Post-Office is done by steamers, and all the passengers and much of the goods' traffic between the parts of Great Britain and Ireland, have been within the last quarter of a century transferred to them.

"After the steamboat had thus passed through the various stages of infancy and childhood—had tried its strength on English rivers, in the Irish Sea, and in the British Channel—men began to ask, was it not strong enough and old enough to do more? Could it not cross an ocean as well as a channel—take letters and men, and merchandise to America, India, and Australia, as well as to Ireland and France? In this question were involved considerations of the highest importance to all the world, but particularly to this country, for no other country has such extensive foreign possessions as Great Britain, or carries on such an extensive trade.

"With the exception of the United States, all the colonies planted by the British remain parts of the empire, while Spain and Portugal have lost nearly all those rich territories, extending over the fairest portion of the American continent, that at one time acknowledged the sway of the houses of Bourbon and Braganza. The foreign possessions of France are insignificant, and, of the other nations of Europe, the Dutch alone possess a territory abroad greater than they have at home.... The proud position of Britain among the nations, the necessities of her foreign trade, and the wants of her colonies and dependencies, apart from all other considerations, rendered it fitting and natural that she should lead the way in maritime enterprise, and teach the nations how to navigate the ocean by steam.

"Nor has she failed in this high task; for, within thirteen or fourteen years, since the question was first proposed, she has established lines of gigantic steam-vessels that are now traversing with regularity and safety every ocean, steaming altogether more than a million and a quarter miles every year, and distributing letters and newspapers all over the world, at a cost to the country of about £650,000 per annum."

The rapidity and ease with which thousands of troops were lately conveyed to the Crimea and India, together with all their stores, horses, &c., form one of the most wonderful feats of ocean navigation ever performed, and point out the beauty of those arrangements which enable man to traverse the whole earth, whether by land or by water, so that it may fairly be said that the civilisation of the world depended and still depends upon the waters.