Various
Blackwood's Edinburgh Magazine, Volume 66, No. 408, January 1849
PHYSICAL GEOGRAPHY. 14
We have here combined the best of all books, and the best of all maps, for the study of the most interesting description of geography. Mr Johnston's Physical Atlas, now published in a form which renders it accessible to greater numbers, is without a rival as a companion and guide in this department of study; and by dwelling on its merits and utility, we should be only echoing a verdict which has already been pronounced by almost every journal of scientific or critical celebrity. And, indeed, the same might be said of our commendation of Mrs Somerville's book; our praise comes lagging in the rear, and is well-nigh superfluous. But not only are we desirous to tender our tribute of respect to one who has done more than any other living writer to extend amongst us sound, as well as general knowledge of physical science; we are anxious also to recommend to our youth the enlarged method of studying geography, which her present work demonstrates to be as captivating as it is instructive.
Mrs Somerville's Physical Geography does not assume so profound an aspect, nor has it so lofty an aim, as the Cosmos of Alexander Von Humboldt; neither can it claim, like that work, to be written by one who has himself surveyed the greater part of the terraqueous globe he undertakes to describe. This latter circumstance gives an extraordinary interest to the Cosmos. From time to time the professor of science, gleaning his knowledge from books, and laboratories, and museums, steps aside, and we hear, and almost see, the adventurous traveller, the man Humboldt himself, who seems to speak to us from the distant ocean he has traversed, or the sublime mountain heights he has ascended. Our countrywoman can claim no such peculiar prerogative. Who else can? To few – to none other – has it ever been permitted to combine so wide a range of knowledge with so wide a range of vision – to have carried his mind through all science, and his eye over all regions. He is familiar with all the grandeurs of our earth. He speaks with the air of the mountain still around him. When he discourses of the Himalaya or the Andes, it is with the vivid impression of one whose footsteps are still lying uneffaced amongst their rarely-trodden and precipitous passes. The phenomena he describes he has seen. He can reveal to us, and make us feel with him, that strange impression which "the first earthquake" makes even upon the most educated and reflective man, who suddenly finds his old faith shaken in the stability of the earth. And what lecturer upon electricity could ever arrest the attention of his auditors by so charming a reference to his personal experience as is contained in the following passage? —
"It was not without surprise that I noticed, on the shores of the Orinoco, children belonging to tribes in the lowest stage of barbarism amusing themselves by rubbing the dry, flat, shining seeds of a leguminous climbing plant (probably a negretia) for the purpose of causing them to attract fibres of cotton or bamboo. It was a sight well fitted to leave on the mind of a thoughtful spectator a deep and serious impression. How wide is the interval which separates the simple knowledge of the excitement of electricity by friction, shown in the sports of these naked, copper-coloured children of the forest, from the invention of the metallic conductor, which draws the swift lightning from the storm-cloud – of the voltaic pile, capable of effecting chemical decomposition – of a magnetic apparatus, evolving light – and of the magnetic telegraph!"
The writer naturally reflects on the wide interval which separates the knowledge of electricity shown by these naked children on the banks of the Orinoco, and the inventions of modern science, which have taught the lightnings of heaven to do our messages on the earth. But, to our mind, this wide interval is far more strikingly displayed by the picture which is here presented to the imagination, of the profound and meditative European looking down, pleased and surprised, at the first unconscious steps in experimental philosophy which these copper-coloured children of the forest are making in their sport.
But if Mrs Somerville's book has none of this extraordinary interest which the great traveller has thrown over his work, and if it does not aspire to that philosophic unity of view, (of which a word hereafter, in passing,) it must take precedence of this, and of all other works, as a useful compendium of the latest discoveries, and the soundest knowledge we possess, in the various subjects it embraces. Nowhere, except in her own previous work, The Connexion of the Physical Sciences, is there to be found so large a store of well-selected information, so lucidly set forth. In surveying and grouping together whatever has been seen by the eyes of others, or detected by their laborious investigations, she is not surpassed by any one; and the absence of all higher aim, or more original effort, is favourable to this distinctness of exposition. We have no obscurities other than what the imperfect state of science itself involves her in; no dissertations which are felt to interrupt or delay. She strings her beads distinct and close together. With quiet perspicacity she seizes at once whatever is most interesting and most captivating in her subject.
The Cosmos of Humboldt has the ambitious aim of presenting to us the universe, so far as we know it, in that beauty of harmony which results from a whole. Thus, at least, we understand his intention. He would domineer, as with an eagle's glance, over the known creation, and embrace it in its unity, displaying to us that beauty which exists in the harmony of all its parts. The attempt no one would depreciate or decry, but manifestly the imperfect state of science forbids its execution. We have attained no point of view from which we can survey the world as one harmonious whole. Our knowledge is fragmentary, uncertain, imperfect; and the most philosophic mind cannot reduce it into any shape in which it shall appear other than uncertain and fragmentary. We cannot "stand in the sun," as Coleridge says in his fine verse, and survey creation; we have no such luminous standing-point. There never, indeed, was a time when the attempt to harmonise our knowledge, and view the universe of things "in the beauty of unity," was so hopeless, so desperate. For the old theories, the old methods of representing to the imagination the more subtle and invisible agencies of the physical world, are shaken, or exploded, and nothing new has been able to take their place. What is new, and what is old, are alike unsettled, unconfirmed. In reality, therefore, the work of Mrs Somerville is as much a Cosmos as that of Von Humboldt; and, as a work of instruction, is far better for not aiming higher than it does. Mrs Somerville presents to us each gospel of science – if we may give that title to its imperfect revelations – and does not bewilder or confuse by attempting that "harmony of the gospels" which the scientific expositor is, as yet, unable to accomplish.
As yet, we have said – but, indeed, will science be ever able to realise this aspiration of the intellect after unity and completeness of view? To the reflective mind, human science presents this singular aspect. Whilst the speculative reason of man continually seeks after unity, strives to see the many in the one – as the Platonist would express himself – or, as we should rather say, strives to resolve the multiplicity of phenomena into a few ultimate causes, so as to create for itself a whole, some rounded system which the intellectual vision call embrace; the discoveries of science, by which it hopes and strives to realise this end, do in fact, at every stage, increase the apparent complexity of the phenomena. The new agencies, or causes, which are brought to light, if they explain what before was anomalous and obscure, become themselves the source of innumerable difficulties and conjectures. Each discovery stirs more questions than it sets at rest. What, on its first introduction, promised to explain so many things, is found, on further acquaintance, to have added but one more to the inexplicable facts around us. With each step, also, in our inquiry, the physical agents that are revealed to us become more subtle, more calculated to excite and to elude our curiosity. Already, half our science is occupied with matter that is invisible. From time to time some grand generalisation is proposed – electricity is now the evoked spirit which is to help us through our besetting difficulties – but, fast as the theory is formed, some new fact emerges that will not range itself within it; the cautious thinker steps back, and acknowledges that the effort is as yet premature. It always will be premature.
There is a perpetual antagonism between the intellectual tendency to reduce all phenomena to a harmonious and complete system, and that increase of knowledge which, while it seems to favour the attempt, renders it more and more impracticable. With our limited powers, we cannot embrace the whole; and therefore it must follow, that it is only when our knowledge is scanty, that we seem capable of the task. Every addition to that knowledge, from the time that Thales would have reduced all things to the one element of water, has rendered the task more hopeless. And as science was never so far advanced as at the present time, so this antagonism was never so clearly illustrated between the effort of reason to generalise, and the influx of broken knowledge, reducing the overtasked intellect to despair. How much has lately been revealed to us of the more subtle powers and processes of nature – of light, of heat, of electricity! How tempting the generalisations offered to our view! We seem to be, at least, upon the eve of some great discovery which will explain all: an illusion which is destined to prompt the researches of the ardent spirits of every age. They will always be on the eve of some great discovery which is to place the clue of the labyrinth into their hand. The new discovery, like its predecessor, will add only another chamber to the interminable labyrinth.
Let us, for instance, suppose that we have discovered, in electricity, the cause of that attraction to which we had confided the revolution of the planets; of that chemical affinity to which we had ascribed the various combinations of those ultimate atoms of which the material world is presumed to be composed; of that vital principle which assimilates in the plant, and grows and feels in the animal. Let us suppose that this is a sound generalisation; yet, as electricity cannot be alone both attraction in the mass, and chemical affinity in the atom, and irritability and susceptibility in the fibre and the nerve, what has the speculative reason attained but to the knowledge of a new and necessary agent, producing different effects according to the different conditions in which, and the different co-agencies with which it operates? These conditions, these co-agencies, are all to be discovered. It is one flash of light, revealing a whole world of ignorance.
To the explanation of the most obstinate of all problems – the nature of the vital principle – we seem to have made a great step when we introduce a current of electricity circulating through the nerves. If this hypothesis be established, we shall probably have made a valuable and very useful addition to our stock of knowledge; but we shall be as far as ever from solving the problem of the vital principle. We have now a current of electricity circulating along the nerves, as we had before a current of blood, circulating through the veins and arteries; the one may become as prominent and as important a fact in the science of the physician as the other; but it will be equally powerless with the old discovery of Harvey to explain the ultimate cause of vitality. To the speculative reason it has but complicated the phenomena of animal life.
Within the memory of a living man, there has been such progress and revolution in science, that not one of the great generalisations taught him in his youth can be now received as uncontested propositions. Not many years ago, how commodiously a few words, such as attraction, caloric, affinity, rays of light, and others, could be used, and how much they seemed to explain! Caloric was a fluid, unseen indeed, but very obedient to the imagination – expanding bodies, and radiating from one to the other in a quite orderly manner. What is it now? Perhaps the vibration of a subtle ether interfused through all bodies; perhaps the vibration of the atomic parts themselves of those bodies. Who will venture to say? Attraction and affinity are no longer the clearly defined ultimate facts they seemed to be; we know so much, at least, that they are intimately connected with electrical phenomena, though not to what extent. That electricity is implicated with chemical composition, and recomposition, is clearly recognised; and Sir J. Herschel has lately expressed his opinion, that it is impossible any longer to attempt the explanation of the movements of all the heavenly bodies by simple attraction, as understood in the Newtonian theory – these comets, with their trains perversely turned from the sun, deranging sadly our systematic views. The ray of light, which, with its reflection and its refraction, seemed a quite manageable substance, has deserted us, and we have an ethereal fluid – the same as that which constitutes heat, or another – substituted in its stead. Science has no language, and knows not how to speak. If she lectures one day upon the "polarisation" of light, she professes the next not to know what she means by the term; she is driven even to talk of "invisible rays" of light, or chemical rays. Never was it so difficult to form any scientific conception on these subjects, or to speak of them with any consistency. Mrs Somerville is a correct writer; yet she opens her brief section upon magnetism thus: – "Magnetism is one of those unseen imponderable existences, which, like electricity and heat, are known only by their effects. It is certainly identical with electricity, for," &c. It is like, and it is identical, in almost the same sentence.
Even in the fields of astronomy, where we have to deal with large masses of matter, it is no longer possible for the imagination to form any embraceable system. We are plunged into hopeless infinitude, and the little regularities we had painfully delineated on the heavens are all effaced. The earth had been torn from its moorings and sent revolving through space, but it revolved round a central stationary sun. Here, at least, was something stable. The sun was a fixed centre for our minds, as well as for the planetary system. But the sun himself has been uprooted, and revolves round some other centre – we know not what – or else travels on through infinite space – we know not whither. A little time ago, the stately seven rolled round their central orb in clear and uninterrupted space; their number has been constantly increasing; we reckon now seventeen planetary bodies that can be reduced to no law of proportion or harmony, either as to their size, their orbits, the inclination of their axes, or any other planetary property;15 and the space they circulate in is intruded on by other smaller and miscellaneous bodies, asteroids, and the like, some of which, it seems, occasionally fall to the earth. Comets come sweeping in from illimitable space, requiring, it is thought, some eight thousand years for their revolution round the sun. Some of these cross each other's orbits: one has crossed the orbit of the earth; and their decreasing circle round the sun, gives notice of some unknown ether suffused through the interstellar spaces. The outlying prospect, beyond our system, grows still more bewildering. The stars are no longer "fixed," nor is their brilliancy secured to them; this increases and diminishes with perplexing mystery. What seemed a single point of light, resolves itself into two stars revolving round each, perhaps reciprocally sun and planet. The faint and telescopic nebula, just reached by the glass in one age, is found in the next to be a congregation of innumerable stars. Our milky way is, at the same distance, just such another nebula. "The elder Herschel calculates that the light of the most distant nebula, discovered by his forty-feet refractor, requires two millions of years to reach our eyes." Oh, shut up the telescope! the reason reels.
Science, in short, presents before us a field of perpetual activity – of endless excitement, and that of the highest order – of practical results of the greatest utility and most beneficial description; but it gives no prospect of any resting-place – any repose for the speculative reason – any position with which the scientific mind shall be content, and from which it shall embrace the scene before it in its unity and harmony. Always will it be
"Moving about in worlds half-realised."
Having touched upon these subtle agencies of light, and heat, and electricity, and on the increasing difficulty we have of framing to ourselves any distinct conception of them, we cannot refrain from alluding to a little work or pamphlet, by Mr Grove, entitled, The Correlation of Physical Forces, in which this subject is treated with great originality. Mr Grove has made himself a name in experimental science by his discoveries in electricity and chemistry; in this pamphlet he shows, that he has the taste and power for enlarged speculation on the truths which experiment brings to light. We would recommend the perusal of his pamphlet to all who are interested in these higher and more abstract speculations. How far the wide generalisation he adopts is sustained by facts, we are not prepared to say. But it is a powerful work, and it is a singular one; for it is not often, in this country at least, that a man so well versed in the minutiæ of science ventures upon so bold a style of generalisation. After reviewing some of the more lately discovered properties of electricity, heat, light, and magnetism, and showing how each of them is capable of producing or resolving itself into the others, he reasons that all the four are but the varied activity of one and the same element. He adds, that this element is probably no other than the primitive atom itself; and that, in fact, these may be all regarded as affections of matter, which follow in their legal sequence, and not as the results of separate fluids or ethers. We are not sure that we do justice to his views, as we have not the work at hand, and it is some time since we read it; but we are persuaded that its perusal will be of interest to a philosophic reader, though its reasoning should fail to satisfy him.
But we have not placed the title of Mrs Somerville's book at the head of this paper, as an occasion to involve ourselves in these dark and abstract discussions. We are for out-of-door life; we would survey this visible round world, whose various regions, with their products and their inhabitants, she has brought before us.
"Physical geography," thus commences our writer, "is a description of the earth, the sea, and the air, with their inhabitants animal and vegetable, of the distribution of these organised beings, and the causes of that distribution. Political and arbitrary divisions are disregarded: the sea and the land are considered only with respect to these great features, that have been stamped upon them by the hand of the Almighty; and man himself is viewed but as a fellow-inhabitant of the globe with other created things, yet influencing them to a certain extent by his actions, and influenced in return."
Physical geography stands thus in contrast with political and historical geography. Russia is here no despotism, and America no democracy; they are only portions of the globe inhabited by certain races. To some persons it will doubtless seem a strange "geography" that takes no notice of the city, and respects not at all the boundaries of states. Those to whom the name recalls only the early labours of the school-room, when counties and county-towns formed a great branch of learning – where the blue and red lines upon the map were so anxiously traced, and where, doubtless, some suspicion arose that the earth itself was marked out by corresponding lines, or something equivalent to them – will hardly admit that to be geography which takes no note of these essential demarcations, or allow that to be a map in which the very city they live in cannot be found. To them the Physical Atlas will still seem nothing but a series of maps, in which most of the names have still to be inserted. They unconsciously regard cities and provinces as the primary objects and natural divisions of the earth. They share something of the feeling of that good man, more pious than reflective, who noted it as all especial providence that all the great rivers ran by the great towns.
Others, however, will be glad to escape for a time from these landmarks which man has put upon the earth, and to regard it in its great natural lineaments of continent and sea, mountain and island. To do this with advantage, it is necessary to disembarrass ourselves, both in the book and the map, of much that in our usual nomenclature ranks pre-eminently as geography. Nor is it easy to study this, more than the older branch of geography, without an appropriate atlas. To turn over the maps of Mr Johnston's, and con the varied information which accompanies them, is itself a study, and no disagreeable one. Of the extent of this information we can give no idea by extract or quotation; it is manifestly in too condensed a form for quotation; it is a perfect storehouse of knowledge, gathered from the best authorities.
The first thing which strikes an observant person, on looking over a map, or turning round a globe, is the unequal division and distribution of land and water. Over little more than one-fourth of the surface of the earth does dry land appear; the remaining three-fourths are overflowed by water. And this land is by no means equally disposed over the globe. Far the greater part of it lies in the northern hemisphere. "In the northern hemisphere it is three times greater than the south."
Of the form which this land assumes, the following peculiarities have been noticed: —
"The tendency of the land to assume a peninsular form is very remarkable, and it is still more so that almost all the peninsulas tend to the south – circumstances that depend on some unknown cause which seems to have acted very extensively. The continents of South America, Africa, and Greenland, are peninsulas on a gigantic scale, all tending to the south; the Asiatic peninsula of India, the Indo-Chinese peninsula, those of Corea, Kamtchatka, of Florida, California, and Aliaska, in North America, as well as the European peninsulas of Norway and Sweden, Spain and Portugal, Italy and Greece, take the same direction. All the latter have a rounded form except Italy, whereas most of the others terminate sharply, especially the continents of South America and Africa, India, and Greenland, which have the pointed form of wedges; while some are long and narrow, as California, Aliaska, and Malacca. Many of the peninsulas have an island, or group of islands, at their extremity – as South America, which terminates with the group of Terra del Fuego; India has Ceylon; Malacca has Sumatra and Banca; the southern extremity of New Holland ends in Van Diemen's Land; a chain of islands run from the end of the peninsula of Aliaska; Greenland has a group of islands at its extremity; and Sicily lies close to the termination of Italy. It has been observed, as another peculiarity in the structure of peninsulas, that they generally terminate boldly, in bluffs, promontories, or mountains, which are often the last portions of the continental chains. South America terminates in Cape Horn, a high promontory which is the visible termination of the Andes; Africa with the Cape of Good Hope; India with Cape Comorin, the last of the Ghauts; New Holland ends with South-East Cape in Van Diemen's Land; and Greenland's farthest point is the elevated bluff of Cape Farewell."
These are peculiarities interesting to notice, and which may hereafter explain, or be explained by, other phenomena. Resemblances and analogies of this kind, whilst they are permitted only to direct and stimulate inquiry, have their legitimate place in science. It was a resemblance of this description, between the zig-zag course of the metalliferous veins, and the path of the lightning, which first suggested the theory, based, of course, on very different reasonings, that electricity had essentially contributed to the formation of those veins – a theory which Mrs Somerville has considered sufficiently sound to introduce into her work.
What lies within our globe is still matter of conjecture. The radius of the earth is 4000 miles, and by one means or another, mining, and the examination of the upheaved strata, and of what volcanoes have thrown out, we are supposed to have penetrated, with speculative vision, to about the depth of ten miles.
"The increase of temperature," writes Mrs Somerville, "with the depth below the surface of the earth, and the tremendous desolation hurled over wide regions by numerous fire-breathing mountains, show that man is removed but a few miles from immense lakes or seas of liquid fire. The very shell on which he stands is unstable under his feet, not only from those temporary convulsions that seem to shake the globe to its centre, but from a slow, almost imperceptible, elevation in some places, and an equally gentle subsidence in others, as if the internal molten matter were subject to secular tides, now heaving and now ebbing; or that the subjacent rocks were in one place expanded and in another contracted by changes in temperature."
Perhaps these "immense lakes or seas of liquid fire" are a little too hastily set down here in our geography. But of these obscure regions beneath the earth, the student must understand he can share only in the best conjectures of scientific men. Geology is compelled, at present, in many cases, to content herself with intelligent conjecture.
To return again to the surface of the earth, the first grand spectacle that strikes us is the mountains. Before it was understood how the mountain was the parent of the river, the noble elevation was apt to be regarded in the light of a ruin, as evidence of some disastrous catastrophe, and Burnett, in his Theory of the Earth, conceived the ideal or normal state of our planet to be that of a smooth ball, smooth as an egg. The notion not only betrays the low state of scientific knowledge in his age, but a miserable taste in world-architecture, which, we may remark in excuse for poor Burnett, was, almost as much as his scientific ignorance, to be shared with the age in which he lived. For it is surprising, with the exception of a few poets, how destitute men were, in his time, of all sympathy with, and admiration of, the grander and more sublime objects of nature. "We have changed all that!" The mountain range, pouring down its streams into the valleys on both sides, is not only recognised as necessary to the fertility of the plain; but, strange to say, we become more and more awake to its surprising beauty and magnificence. The description of the mountain ranges of the several continents of the world, forms one of the principal attractions of the study of physical geography, and one of the great charms of Mrs Somerville's book.
The mountains of Asia take precedence of all others in altitude and length of range.
"The mean height of the Himalaya is stupendous. Captain Gerard and his brother estimated that it could not be less than from 16,000 to 20,000 feet; but, from the average elevation of the passes over these mountains, Baron Humboldt thinks it must be under 15,700 feet. Colonel Sabine estimates it to be only 11,510 feet, though the peaks exceeding that elevation are not to be numbered, especially at the sources of the Sutlej. Indeed, from that river to the Kalee, the chain exhibits an endless succession of the loftiest mountains on earth: forty of them surpass the height of Chimborazo, one of the highest of the Andes, and several reach the height of 25,000 feet at least… The valleys are crevices so deep and narrow, and the mountains that hang over them in menacing cliffs are so lofty, that these abysses are shrouded in perpetual gloom, except where the rays of a vertical sun penetrate their depths. From the steepness of the descent the rivers shoot down with the swiftness of an arrow, filling the caverns with foam and the air with mist.
"Most of the passes over the Himalaya are but little lower than the top of Mont Blanc; many are higher, especially near the Sutlej, where they are from 18,000 to 19,000 feet high; and that north-east of Khoonawur is 20,000 feet above the level of the sea, the highest that has been attempted. All are terrific, and the fatigue and suffering from the rarity of the air in the last 500 feet is not to be described. Animals are as much distressed as human beings, and many of them die; thousands of birds perish from the violence of the winds; the drifting snow is often fatal to travellers, and violent thunder-storms add to the horror of the journey. The Niti Pass, by which Mr Moorcroft ascended to the sacred lake of Manasa, in Tibet, is tremendous: he and his guide had not only to walk bare-footed, from the risk of slipping, but they were obliged to creep along the most frightful chasms, holding by twigs and tufts of grass, and sometimes they crossed deep and awful crevices on a branch of a tree, or on loose stones thrown across. Yet these are the thoroughfares for commerce in the Himalaya, never repaired, nor susceptible of improvement, from frequent landslips and torrents.
"The loftiest peaks, being bare of snow, give great variety of colour and beauty to the scenery, which in these passes is at all times magnificent. During the day, the stupendous size of the mountains, their interminable extent, the variety and sharpness of their forms, and, above all, the tender clearness of their distant outline melting into the pale blue sky, contrasted with the deep azure above, is described as a scene of wild and wonderful beauty. At midnight, when myriads of stars sparkle in the black sky, and the pure blue of the mountains looks deeper still below the pale white gleam of the earth and snow-light, the effect is of unparalleled sublimity; and no language can describe the splendour of the sunbeams at daybreak streaming between the high peaks, and throwing their gigantic shadows on the mountains below. There, far above the habitation of man, no living thing exists, no sound is heard; the very echo of the traveller's footsteps startles him in the awful solitude and silence that reigns in these august dwellings of everlasting snow."
The table-lands of Asia are on a scale corresponding with its mountains. But the same elevation, it is remarked, is not accompanied with the same sterility in these parts of the world, as in the temperate zone. Corn has been found growing at heights exceeding the summit of Mont Blanc. "According to Mr Moorcroft, the sacred lake of Manasa, in Great Tibet, and the surrounding country, is 17,000 feet above the sea, which is 1240 feet higher than Mont Blanc. In this elevated region wheat and barley grow, and many of the fruits of Southern Europe ripen. The city of H'Lassa, in eastern Tibet, the residence of the Grand Lama, is surrounded by vineyards, and is called by the Chinese 'the Realm of Pleasure!'" Nevertheless the general aspect of the table lands is that of a terrific sterility. Here is a striking description of them. We should have been tempted to say, that in this singularly dark appearance of the sky at mid-day, there was something of exaggeration, if our own limited experience had not taught us to be very cautious in attributing exaggeration where the scenic effects of nature are concerned.