adjustments made in order to their operation, are of a regular and mutually adaptive character. The forms of crystals, and the relations of chemical equivalents, if not simple, must, just because they are regular, proceed from forms or from forces, one or both, which are also characterized by regularity. From disorder there can flow only confusion; order can proceed only from order.

SECT. II.-ADAPTATION OF INORGANIC OBJECTS TO ANIMALS AND PLANTS.

Many of the adjustments which might be adduced under this head are so obvious that it is not necessary to dilate on them; indeed, they can scarcely be made more impressive by any scientific treatment. While the elements of nature obey their own methodical laws, they are so arranged as to form living organisms, and supply them with the needful sustenance. Each agent has its rule of action, but is made to co-operate with every other. Law is suited to law, property fits into property, collocation is adapted to collocation, and the result is harmony and beneficence. The whole is dependent on every one of its parts, and the parts all lend their aid to the production of the whole. A break in a single thread of the complicated network would occasion the failure of the whole design.

There are upwards of sixty substances, which, in our present state of knowledge, we must regard as uncompounded. Each of these has its own properties, and the system is sustained by the joint action of all. Very possibly the absence of any one of the elements, certainly the absence of any one of the thirteen more universally diffused, would throw the mundane system into confusion. Each has a purpose to serve which could be served by no

other. Oxygen, so essential to animal breath and life, is the most largely distributed of them all, composing more than one half of the whole inorganic objects known to us. Hydrogen, the other element of water, no less necessary to living beings, seems to have a relation to every living organism. Carbon is a main source to us of artificial light and heat. In order that it should fulfil this end, it is necessary that it should be a solid while evolving its light and heat, (a gas has little, and this only a momentary, power of illumination); this is provided for by carbon being in itself always solid. But if the result of combustion had been also a solid, then the world would have been buried in its own ashes; this evil is avoided by the carbon going off in carbonic acid, which is volatile. The mass is all glowing one instant, the next it is dissipated into air. Carbon," says Faraday, possesses every quality to render it adapted to its intended uses; not one property, however seemingly unimportant, could be added or taken away without destroying the whole harmonious scheme of nature, devised with such wisdom, maintained with such care."1

Each of the powers and elements of nature is in itself potent, and capable of working destructive effects, but is checked and balanced by nice adjustments. What tremendous energies does oxygen display in the phenomena of combustion, and when in the condition of ozone; yet how tranquil and passive as one of the elements of water, and as locked up in so many of the constituents of the earth's crust. The electric force held in balance in a single drop of water would, if let loose, exceed in energy the electricity of a thunder-storm. Man is placed in a state of things in which, as he is dependent, he is made every instant to feel his dependence.

1 Letters on Non-Metallic Elements, p. 277.

What a vast number of independent agencies must combine and co-operate in order to the life of organized beings! It is wrong to talk of an organism developing itself by its simple and independent energy. Whatever be its internal nature-in which also, in our opinion, there is complexity and combination-it requires external agents in exact adaptation to it. All plants need nourishment, and this is supplied by inorganic matter; all animals need nourishment, and can be nourished only by matter that has been organized, and this is furnished directly or indirectly by the plant. How beautiful that adjustment by which animals breathe of the oxygen of the atmosphere, and set carbonic acid free for the use of plants, while plants absorb carbonic acid, and set oxygen free for the benefit of animals! Then all animated beings need moisture, which depends on the chemical laws uniting oxygen and hydrogen to form water, and also on heat to retain it in a state of vapour in the air, and on certain adjusted relations, in respect of quantity and weight, to the atmosphere in which it floats. All organized beings, too, depend on light coming in the needed proportion from a distant body, and on heat, the measure of which depends on the state of the central part of the earth, on the radiations of the sun, and on the temperature of the regions of space. A considerable change in any one of these essential conditions would be fatal to the whole animated beings on the earth's surface.

But instead of dwelling on these familiar topics, we shall turn to, perhaps not so conclusive, but still to a less known set of facts, in which it has been supposed that disorder reigns.

We have, in a previous chapter, brought forward some evidences of adaptation in the march of events which preceded man's epoch, and which have given rise to im

portant changes on the earth's surface, to fit it as the dwelling-place of animals and plants, and apparently effected with a view more especially to the advent of man. In the development of this scheme, a suitable vegetation was called into being, animal tribes were introduced, with the command to multiply, and finally, to man was committed a power over every living thing.

Our aim, in the present section, is to show that there are traces of fitness in the general aspect of the earth's contour, in the arrangement of its dry land and waters, and in the relations of its surface to temperature and moisture; and that these, in turn, have some connexion, more or less evident, with the distribution of animal and vegetable life, and also with the wellbeing of the human family.

The study of Physical Geography, which has of late years come into prominence, has little or no reference to those arbitrary divisions of the world which occupy the attention of the mere geographer. In examining the structure of the earth's surface physically, attention is rather directed to the valleys and elevations which diversify its surface-those furrows drawn by the hand of time, and the mountains which, by their upheaval, have so remarkably diversified it, and indirectly have such important bearing on the existence and wellbeing of animals and plants. Those deep furrows and prominent ridges, constituting so remarkable a feature of the earth, are lasting records of the great changes to which it has been subjected: we cannot suppose them to have been fixed by mere chance; they bear distinct traces of subjection to those great principles which regulate all the plans of Him, every part of whose works is adapted to every other.

The investigations of observers in different ages have

established the following leading truths in regard to this subject.

Land predominates in the northern hemisphere, water in the southern; the lands comprising the old and new worlds stand at right angles to each other; the new world is perpendicular to the equator, the old parallel to it. In reference to the contour of the dry land, it has been observed, that the southern ends of the old and new worlds terminate in a point, while they widen toward the north; that the southern points are high and rocky; that the continents present, to the east of their southern extremities, a large island or group of islands; and that each continent has a large gulf to the west. Humboldt H has indicated the parallelism of the two sides of the Atlantic; the projecting parts of the one correspond to the gulfs of the other. Steffens has remarked, that not only do the great continents expand towards the north, and become narrower toward the south, but that the same is true of their peninsulas also. He speaks, likewise, of the grouping of masses of land two and two together, and points out an isthmus or chain of islands uniting them.

Guyot, in his "Earth and Man," enunciates the follow- Guyot

ing great laws, which apply to all continents in regard to their relief or elevation:-All increase gradually in height from the shore to the interior; in all the continents the maximum of elevation is not in the centrehence there are two slopes of unequal length, and in the mean, one of these slopes is always at least four or five times greater than the other; and the height of the plains and of the table-lands increases at the same time with the absolute elevation of the mountains. In the old world, though the principal slope is toward the north, we still observe a gradual decrease of the reliefs from