Part 16

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 1/59^2 or 1/3481, the point C with the force of 1/60^2 or 1/3600, and the point D with the force of 1/61^2 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 4-1/2 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.

INTRODUCTION TO THE ORGANIC KINGDOMS OF NATURE.

The foregoing descriptions refer to the great works of God as seen in those creations which possess not that most wonderful attribute--life. There is no limit in extent, in quality, or in number, to these works; their extension appears to be infinite; their magnitudes are large or small, just as we compare them one with the other. This earth is an enormous mass, contemplated in comparison with ourselves, but an insignificant speck when compared with the sun, and there are certain laws, chemical and mechanical, which govern them all--heat, light, and electricity permeate all the infinity of space--attraction exists everywhere. There are no individual existences among them; all are made up of matter combined according to certain definite chemical laws, and always obedient to them under the same conditions--moving according to certain mechanical laws, and always obedient to them. The Creator who made these lifeless masses made also the laws to regulate them; but, besides these, it has pleased Him to form certain other creatures not for an instant to be compared in size or quantity with the former, and made up also of certain chemical compounds obedient to the mechanical and chemical laws, with one more addition, that unknown, inexplicable attribute--life. This wonderful quality exists in all organic beings; they obtain by it individual identity; they are whole creatures--imperfect with any part taken away, also imperfect with any addition. Clay is clay, in any quality or form; iron is iron, whether a grain or a ton; but a tree is only a tree when it is complete. We cannot say "some tree," as we would "some clay," it must be a tree, or several trees, each a separate and complete existence--perfect in itself--made up of solids and fluids, and possessing certain attributes, namely, a constant circulation of its fluid parts, a constant appropriation of food and rejection of waste matters--growth thereby to a certain definite form, and in many a definite size, together with the production of germs, capable, under certain conditions, of producing beings exactly similar to themselves. This constitutes organic life, and is possessed by all vegetables. Animal life is exactly the same, with the super-addition of will or mind in its most perfect state, of instinct or some analogous function in its lower states, or in quite the lowest--a chemical and mechanical difference only, such as shall determine the choice of food and mode of assimilating it. This difference consists in the vegetable feeding upon inorganic food, and the animal on food which has received the stamp of organisation. Creatures possessing life, whether vegetable or animal, are called organisms. It is found that these organisms are made up of certain atoms united in larger multiples than in inorganic substances, which are either simple or compounded of but few atoms; thus water is composed (every atom of it) of one atom oxygen, united to two of hydrogen. Common salt (every atom of it) is composed of one atom of the metal sodium with one atom of chlorine. Chalk is compounded of one atom of calcium in union with one of oxygen, and this united to one atom of carbonic acid, itself composed of one atom of carbon with two of oxygen. But organic compounds are often made up of four or six elements, united in multiples of their usual combining quantities. Thus, grape-sugar is made up (every atom of it) of 24 atoms of carbon, 28 of hydrogen and 28 of oxygen; these 78 atoms unite and form one compound atom, of which the sugar is wholly compounded, and thus, from such a complex nature, it happens that most organic compounds are decomposed by even a moderate degree of heat--all by a heat equal to red-hot iron. From these facts, it may be therefore stated, that all organisms are complete in themselves, have definite lives or existences, appropriate certain matters to themselves, grow thereby, and are compounded of organic atoms.

THE VEGETABLE KINGDOM.

QUANTITY, DISTRIBUTION, AND OFFICES OF THE VEGETABLE.

In contemplating nature there are few things which give more delight than the beauty and variety of the vegetation which clothes the surface of the earth, whether it be that we contemplate the grassy covering of the plains of the Old World, or the immense "prairies" of the New, spreading out as it were into seas of grass, and giving food and shelter to thousands of wild animals; or gaze upon the rocky height of some vast mountain range, and see the gigantic oak or pine, forming by their wide-spread shades the solemn forest which extends for miles beneath us, and which forms a shelter for the various tribes of birds, monkeys, and other animals, to whom it is a home of happiness and plenty--under every aspect the contemplation of nature's clothing fills the mind with awe and admiration.

There is hardly anything more refreshing to the mind than the contemplation of trees and shrubs congregated into a wood, the floor of which is carpeted with mosses and flowers, where the gigantic and gnarled trunks of the forest trees covered with many-coloured lichens starting up all round, circumscribe the view, while the wide-spreading boughs and the leafy canopy overhead exclude the sun's rays. It is here that one views nature in her purest forms and colours, untouched by the destroying hand of artificial arrangement.

The immense preponderance of the vegetable over the animal world in quantity compensates somewhat for the superior organisation and the intelligence of the latter, which must be studied in the individual, while the vegetable world, which can be contemplated in the mass, almost overwhelms the imagination with its vastness. It is indeed impossible to compute the amount of vegetation in the great forests of America and Russia (in which latter country are the largest in the world), covering hundreds, nay thousands, of square miles with one continuous growth of timber. That forest in Russia through which the river Pechora flows, extends over a space of 150,000 square miles! The whole mass of animated existence sinks into insignificance when compared in quantity with this; and when to these forest-tracts are added the thousands of square miles of grass and heaths which grow in some climates with wonderful luxuriance, the amount of the vegetable kingdom is at once placed beyond all comparison with the animal kingdom in point of quantity. Cooper, in his American novels, describes the prairies as great seas of grass extending as far as the eye can reach, and rising to a height of 8 or 10 feet; and Humboldt describes some of the grasses on the plains of the Oronoco, as being so gigantic that they measure 18 feet from knot to knot, and says the Indians use them for blow-pipes to shoot their poisoned arrows from. And--as though it were not sufficient that the earth should bring forth everywhere all kinds of trees, shrubs, and grasses--the waters of the ocean itself are often filled with vegetable life; in some tracks the tangled sea-weed (Fucus Natans) is so dense as to impede the onward progress of ships for hundreds of miles together.

Humboldt, in his "Views of Nature," describing the two great banks of sea-weed, says: "The two banks of sea-weed, together with the transverse band uniting them, constitute the Sargasso Sea of the older writers, and collectively occupy an area equal to six or seven times that of Germany."

Nor is this the only vegetation which the great world of waters contains, for if we descend from the contemplation of its larger members we find them even surpassed in quantity by others of such extreme smallness, that they can only be seen individually by means of the microscope, but which exist in such prodigious quantities that the mind can hardly realise the fact. These vegetable atoms have been so increasing and depositing their minute coverings at the bottom of most parts of the ocean, that for hundreds of miles their beds are composed of nothing else, and it has been found that most of the great changes on the surface of the earth have been effected by these minute creatures and their companions of the animal world; for as we find chalk-downs and coral-reefs formed by the remains of microscopic animals, so productions of equal extent have been formed by the smallest members of the vegetable kingdom, chiefly the "Diatomaceæ," a race of minute vegetable productions which propagate by sub-division and have the power of withdrawing earthy matters from the waters in which they live, which forms a sort of shell or covering; this shell at their death remains indestructible and gradually accumulates in the bed of the sea (fig. 1). Examination of the various strata of the earth shows that chains of hills, beds of marl, and almost every kind of soil, whether superficial or raised from a depth, consist in a great proportion of the earthy remains of these minute plants. These tracts of land were once the beds of oceans which were thus gradually filled up. The waters of the Antarctic Ocean are often opaque and quite brown from the multiplicity of these creatures, the lead used on shipboard for sounding coming up from the bottom covered with what appears to be mud, but which on a microscopic examination proves to be nothing else than the shells of these and allied species (fig. 2). Thus we find the land and the waters are everywhere full of vegetable life; the air itself moreover is so filled with the germs of vegetable and animal creations, that it is quite impossible to exclude a portion so small that it shall not contain any; in proof of which, any organic substance set by for a few days in a vessel ever so carefully closed, is shortly covered with a growth of mould consisting of fungi, which under the microscope present most beautiful forms and colours (fig. 3). The cause of this is a deposit from the air of the spores or germs of these creatures, and the nature of the decomposing substance into which they fall often determines the race or tribe which shall come to life and inhabit it, showing plainly that but a few of these only among many come to maturity, just as when a variety of seeds are thrown on any particular kind of soil, only those to which the soil may be suitable come to perfection.