commonly reflected along with it. In this way, we can account for the endless diversity of hues that result from the seven primary colors; for the proportions in which the several rays may be reflected together are indefinitely

numerous.

We can only conjecture the cause of bodies reflecting one' class of rays and absorbing others, so as to appear to our eye of a certain color. It probably consists in a peculiar arrangement of their minute particles. This arrangement may be destroyed by mechanical or chemical agency; which will account for the changes of color in bodies exposed to the weather, or to any chemical action. The process of dyeing is only the spreading over the surface of one body, the particles of another of a different color, which, however, can scarcely be effected without producing some chemical change in the dyed substance. The rays of light, which, in solid bodies, hardly penetrate the surface, are reflected or absorbed by the dyeing matter, and the original color of the body is consequently lost.

Colors are spread over all Nature with exquisite beauty and adaptation. The earth is clothed with a mantle of delightful green, interspersed with the more brilliant hues of shrubs, trees, and flowers. In point of refrangibility, green holds the middle place between the two extremes of violet and red. Neither too dark nor too bright, on it the eye, when wearied with livelier or more sombre colors, delights to repose. Were the earth's surface of a black color, it would be even distressing to look upon, as the eye and mind are at present constituted. Or,were white the prevailing hue, our eyes would be dazzled with excessive brightness, and would turn away from all objects with pain and weariness. The color of the sky is a deep blue, contrasting pleasingly with the soft green of the earth. The blueness of the sky may be caused by the particles of air, and the minute globules of moisture, constantly floating among them, reflecting the blue rays; or it may result from the circumstance, that, of all the rays reflected from the earth into the atmosphere, the blue, being most refracted, have the least momentum,

and are consequently more liable to be reflected back to the eye. Nor is variety of hue wanting in the regions of the air. Clouds of almost all colors and varieties of tinge, frequently move before the delighted eye, like the splendid scenes of a vast theatre. The sparkling lustre of universal sunshine, the lurid glare of the thunder cloud, the crimson streaks of morning, and the rich and ever-varying glories of sunset, successively solicit our admiration and delight. Yet the eye would tire even of these, if of continual occurrence; and hence the prevailing hue which has been chosen is the pure azure of the unclouded atmosphere, or the sombre shade of the rain-cloud.

The color of the ocean varies considerably with local circumstances. Its generic color is dark blue, but in different places it is green, red, or yellow. Various causes may be assigned for the discoloration of the oceanic waters. The nature of the bottom, the weeds and insects upon the surface, the substances and solutions discharged into them by large rivers, all contribute to affect their color. But the prevailing hues of the ocean are dark and cool, which are at once pleasant and refreshing to the eye, even when accustomed to them during the months of a long voyage. Yet the ocean is often strewn with wreaths of foam, and has its vast billows, crested with white, and rolling in dreadful beauty to the shore. And the foamy whiteness of its agitation is not without its use, independent of its variety and grandeur; for it points out to the voyager the existence of danger, warns him of the approaching storm, and discovers to his distant eye the hidden reef or shoal, and the breakers of a rocky coast.

The variety of Nature depends still more upon the figure of bodies than upon their color. Figure is an essential property of matter. All bodies, and even the elementary particles of which common substances-the familiar objects of sight and touch-are composed, must, from their very nature, be extended in space, and possess length, breadth, and thickness, which have been termed the limits of extension. We can scarcely conceive of

bodies as masses of matter extended in space, without also thinking of their property of figure; because, figure is the inevitable result of limited extension, and may, indeed, be defined to be the shape or appearance any body presents, from its occupying a certain quantity of space in certain directions.

Figure is almost as varied as the productions and phenomena of Nature are numerous. In the vast and in the minute world, its diversity is equally striking and apparent. We can conceive no bounds to its diversity, which, in reality, is as infinite as number or quantity. The forms which matter has assumed upon our globe, defy computation; and how shall we pretend to estimate, or even to conceive, what forms it is capable of assuming? Figure is either symmetrical or irregular. In the productions of Nature there is usually a symmetry and regularity of form, which can hardly escape the most unpractised eye. Who does not observe, or, observing, is insensible to, the effect of the graceful curved lines that prevail in the animal and vegetable worlds, or of the symmetrical angular forms assumed by minerals and crystals? The property of figure in bodies is the source of half the pleasure we enjoy in our intercourse with Nature. It is of itself a fountain of beauty. It equally seizes the attention of the lover of scenery and the naturalist; is as efficient in exciting pleasing emotions when perceived in the harmonious and beautiful landscape, in the rain-cloud, the hail, the dew, or the snow, as in the graceful form of a flower, or the wreathings of a shell.

It is a curious subject of reflection, that, however great may be the diversity of figure at present existing among solid bodies, yet, in certain specifiable circumstances, they would all assume a globular form. When we contemplate the visible universe, we discover it to consist of an innumerable collection of spheres; and what is true of the suns and satellites that adorn the firmament, has also been proved true of our earth. We know, therefore, the forms which the vast bodies that fill the infinitude of space have assumed, on being hurled from the hand of their Creator. But we also know what form a body

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would assume in empty space, provided only the cohesive attraction of its component particles were so subdued as to allow gravitation to act freely. It is more than probable that all solids might be reduced to a liquid state. Their cohesion has only to be overcome by heat to a certain extent, and they become fluids. Now, fluids, as they fall through space, are invariably transformed into globules. The phenomena of rain, and of molten lead let fall from a height, are wellknown instances of this, and require no description.

Difference of size is another element of the variety of Nature. The distinction between size and figure is natural and obvious. If bodies of the same figure be of different sizes, all the effect of variety is produced. The variety of the heavens, for example, is chiefly that of size. Size, or magnitude, it is evident, is only relative. One body may be large, in relation to another, but insignificantly small, in relation to a third. What is the loftiest mountain-peak, compared to the earth, and the earth, compared to the sun? Yet that peak is a world relatively to a grain of its sand. In Nature, we see an infinite diversity of the magnitudes of bodies, from the sun, that is the centre and life of numerous worlds, down to the mote that flickers in one of his beams. And when, setting out from the opposite extremes of magnitude that come within the reach of our perception, we attempt to measure its ascending and its descending scale, and to find a limit to the vast and the minute, we utterly fail in our efforts; and even imagination itself is overpowered. So illimitable, in both directions, is the universe of God.

Thus, whatever is the property of material substances, be it essential or merely contingent, that comes under our observation, we find in it, Divine benevolence and wisdom. The colors, figures, and sizes of bodies, are infinitely varied, and thereby is the earth agreeably diversified and adorned.

J. D.

FIRST WEEK-THURSDAY.

MOUNTAINS.

FEW objects in Nature have a sublimer aspect, than a chain of lofty mountains before they have recovered from the effects of wintry storms. Disrobed of their summer verdure, and lifting their bare summits in the chill air, or clad in a mantle of drifted snow, they seem to be the chosen haunts of desolation, the wild abode of darkness and storm. Crowned with no ancient forests, and unadorned with human dwellings, unfurrowed by the plough, incapable of cultivation, and but scantily clothed with a poor and stunted herbage, these vast eminences might, at first sight, appear barren and almost useless features in the general landscape,-not without their majesty and grandeur, indeed, in the day of storm or of sunshine, yet unprofitably encroaching upon the beauty and fertility of the plain.

But experience and research have unfolded to us the great advantages of mountains. Were it only because. they are the sources of springs and rivers, we have ample reason to feel grateful for their existence. Their vast masses attract the clouds, and receive in the form of rain, hail, or snow, the vapors with which the atmosphere is charged, even when the plains below are parched with summer drought; and hence the irregular and mountainous surface of the earth is veined over with a multitude of rills, and brooks, and rivers, whose waters, by a wonderful species of circulation, flow to the place whence they came, that mighty and ever-heaving heart, the ocean. Were the earth a dead level, or even slightly varied with hillocks or gentle ascents, the moisture that should fall would be gathered into turbid and sluggish streams, or stagnant lakes, and the whole surface of the ground, more than saturated, would become a vast marsh, sending forth noxious exhalations, pregnant with disease