PHYSICAL GEOGRAPHY.

I.

INTRODUCTORY

OUTLINE.

Aim and Objects of the Science.

1. GEOGRAPHY (from two Greek words, ge, the earth, and graphe, a writing or description) embraces, in its widest sense, all that can be known of the superficial aspects of our globe-its lands and waters, their extent and configuration, their altitude and depth, the atmosphere that surrounds them, their varied conditions and climate, and, finally, the distribution of the plants and animals by which they are respectively peopled. As Geology labours to interpret the rocky structure of the earth, and to write the history of the various mutations that structure may have undergone; so Geography endeavours to describe its external conditions, and to explain the causes by which these conditions are produced, and the purposes for which they are apparently maintained.

2. A science embracing so wide and varied a subject will readily present itself under several heads or departments; and thus we may have what is termed Mathematical Geography, which devotes itself to the size, form, motions, and general divisions of the earth as a planet, forming part of the solar system; Political Geography, which relates to the arbitrary subdivisions of the earth into empires kingdoms, and states, with their populations, manners, religion, laws, industry, commerce, and other features distinctive of such subdivisions; Descriptive or General Geography, which restricts itself to a mere account of the external aspects of the lands and

waters their extent and configuration, their scenery, life, and other obvious features-without inquiring into the causes that produce these appearances; and lastly, we may have Physical Geography, which, while it embraces all the natural conditions of the lands and waters depicted by Descriptive Geography, proceeds further to inquire into the causes that produce these results, and by which they are in the course of nature continually reproduced within certain limits of change and modification.

3. Physical Geography is thus the higher department, its aim being not only to describe the external aspects or the terraqueous (land and water) globe, but to inquire into those conditions of position, altitude, soil, heat, moisture, and the like, which govern the distribution of plants and animals on the land, and those conditions of depth, composition, and temperature, which regulate in a similar manner the distribution of plants and animals in the ocean. The Land, its continents and islands, its mountains and valleys, its soil and climate, its scenery and life-arrangements; the Ocean, its seas and bays, its shoals and depths, its composition and temperature, its aspects and life-dispersion,-are the special objects of Physical Geography; and its highest aim the discovery and expression of those laws which regulate the action and reaction of land, water, and atmosphere in the production of physical phenomena. Physical Geography thus rises above the mere description of external appearances, and seeks to explain the causes that produce themarranging the whole into a system of world-machinery whose modes of action can be understood, and whose results it is possible to determine. In the eloquent language of the author of 'Earth and Man' (M. Guyot)—" Geography ought to be something different from a mere description. It should not only describe, it should compare, it should interpret, it should rise to the how and the wherefore of the phenomena which it describes. It is not enough for it coldly to anatomise the globe, by merely taking cognisance of the arrangement of the various parts which constitute it. It must endeavour to seize those incessant mutual actions of the different portions of physical nature upon each other, of inorganic upon organised beings, upon man in particular, and upon the successive developments of human societies; in a word, studying the reciprocal action of all these forces, the perpetual play of which constitutes what may be called the Life of the Globe, it should, if I may venture to say so, take up its Physiology. To understand it in any other way, is to deprive Geography of its vital principle; it is to make it a collection of partial, unmeaning facts; it is to fasten upon it for ever that character of dryness, with which it has so often and so justly been reproached. For what is dryness in a science,

except the absence of those principles, of those ideas, of those general results, by which well-constituted minds are nurtured?"

4. Rising to this conception of his science, and viewing the beautiful and diversified field before him, the student of Geography meets a problem in every phenomenon that presents itself, and finds a solution in every incident that occurs. Why, for instance, do two countries, lying within the same parallels of latitude, present such differences in climate? Why are mountain-heights perpetually enveloped in snow, while the lower ridges are clothed in verdure and blossom? Why does one region of a continent be arid and rainless, while another is deluged with periodical torrents? Why do the winds in certain latitudes blow steadily and for weeks in one direction, while in another they are fitful and irregular? Why should one expanse of ocean be still and tideless, while another swells and falls with tides, and is traversed by currents? Why should the plants and animals that flourish in one region, dwarf and die out if transferred to another that seems equally fertile in soil and genial in climate? Why should the men at the mountain foot be tillers of fields and dressers of vineyards, while those a thousand feet higher are herdsmen and shepherds? Or why should one country be the scene of busy industry and successful commerce, of intellectual activity and mental culture, while another, as fair and even more fertile, remains the mere squatting-grounds of indolent, dependent, and semi-civilised hordes? These and a thousand similar questions press themselves upon the attention of every geographical observer; and while the facts may be detailed with clearness and accuracy by Descriptive Geography, to Physical Geography, in particular, we must turn for a rational solution of the phenomena presented.

5. In the prosecution of his subject the student of Physical Geography appeals to Astronomy for what relates to the figure, size, motions, and other primary conditions of our planet; to Geology for the structure and constitution of the rocky crust, which forms, as it were, the groundwork of all Geography; to Meteorology for much that belongs to climate and its allied phenomena; while from Chemistry and Physiology he derives important aid in dealing with the nature, growth, and dispersion of plants and animals. There, for example, is an island in the ocean: what is its position on the earth's surface-that is, its latitude and longitude; when will its sun rise and set, compared with some fixed meridian; what are the limits of its seasons; when will its tides ebb and flow; what is the force of gravity at its surface; what the deviation of the magnetic needle? and many other similar questions. These, strictly speaking, belong to Astro

nomy and Mathematics; but the geographer, availing himself of their aid, appeals to them for the solution of these problems. Again, the island is rocky and precipitous towards the north and west, while towards the south and east it falls away in gentle slopes and terraces. The north-western section presents, in the main, a series of basaltic crags and rocky hill-tops, while the south-eastern consists of clays and loams that lie on upturned strata of sandstones, limestones, and shales. There is a small circular lake or tarn up among the hills, while along the junction of the sandstones and basalt numerous springs rise and find their way to the low lands below. This is the structure of the island, and Geology endeavours to explain it. Further, while the hilltops are often enveloped in mists, the lower slopes rejoice in sunshine; and not unfrequently, when the heights are covered with snow, the low grounds are fresh and open. The rainfall on the western coast is several inches more than that on the east; and the north-east winds are cold and parching, while the south-west are warm and laden with moisture. This is its Climatology, and Meteorology lends her aid to an explanation of these opposing phenomena. Still further, the plants that flourish on the basaltic crags are never found on the clayey slopes below; while even on the slopes and terraces different plants affect different soils, though exposed to the same sunshine and moisture. Chemistry and Physiology resolve these problems; and Physical Geography, while it describes and accounts for the whole, must own her obligations to these and other allied departments of natural science. Though drawing, however, in this manner from other sciences, it by no means follows that the student should be deeply read in Astronomy, Geology, or Meteorology. All that is necessary is. that he be able to perceive the connection and interbearings of these sciences, and be capable of appreciating the importance of their deductions in as far as they relate to his own immediate study of Physical Geography.

Theoretical and Practical Bearings.

6. The value of such a science must be obvious to the most casual observer. To determine the relative extent of the land and water that constitute this terraqueous surface-the varying altitudes of the one and the depths of the other, the climates of the one and the winds and currents that traverse the other, with the infinitely diversified mineral, vegetable, and animal productions of both—is not only a source of high intellectual enjoyment

and culture, but a task of prime industrial necessity. This globe is the sole scene of man's earthly labours-his cradle, the theatre of his life-actions, his grave! Scattered over its surface, separated by sea and mountain, enjoying different climates, and placed in proximity to different mineral, vegetable, and animal products, it is a natural necessity that different nations should trade and barter with each other. To ascertain the peculiarities of this varied surface, to learn the variety of its products—to know all, in fine, that relates to the home we tenant, and the comforts and necessaries with which it is furnished, as well as the obstacles or facilities that lie in the way of obtaining them-is the sum and substance of Geography. The observation and reasoning required in geographical research, the amount of information obtained, and the curiosity gratified by faithful descriptions of distant and diverse regions, constitute, on the one hand, its theoretical value; acquaintance with their mineral, vegetable, and animal products, now so indispensable to civilised existence, the conditions under which these occur, and the capability of the latter for naturalisation in other countries, form, on the other hand, its economical or practical importance.

7. To the navigator dependent on the winds and currents of the ocean, what more necessary than a knowledge of the times, directions, and limits of these aërial and aqueous movements? The determination of shoals and sandbanks, of sunken rocks and reefs, is no doubt highly valuable; but it is a higher effort of philosophy to determine the causes and courses of these wind and water currents-to teach the sailor how to shun the storms of the one, and to cast himself on the favouring stream of the other. To the pioneer and settler in new lands, what more important than a knowledge of the climate, the seasons, and the products of his adopted home? or what more valuable than the teachings of Physical Geography to the merchant-traveller in search of new objects of enterprise and sources of wealth? To the botanist and zoologist, who deal with the strictly scientific aspects of natural history, as well as to the gardener and farmer, who seek to naturalise the plants and animals of different regions, there is no science whose bearings are so immediate as that which reveals the geographical distribution of life, and the causes that determine the order of that distribution. To the physiologist and psychologist who would study the influence of climate and other external conditions on health as well as on mental character; and to the political economist and statesman who have to deal with the peculiarities of different nations and the products of their countries, Physical Geography becomes a science of direct and important