The spreading oak, the beech, and towering pine,
Glazed over, in the freezing ether shine.
The frighted birds the rattling branches shun,
That wave and glitter in the distant sun.
When, if a sudden gust of wind arise,
The brittle forest into atoms flies;

The cracking wood beneath the tempest bends,
And in a spangled shower the prospect ends."

Nor must I omit to mention yet another pleasing production of frost, in the elegant and varied foliations which are formed on the glass of windows. This appearance takes place most remarkably in cases where the air within the room happens to have been much impregnated with moisture, either from the human breath, when several individuals have been collected, or from any other cause. The coldness of the glass causes the floating vapour to be condensed on its surface, where it shoots out, as it freezes, into those flowery crystals, which excite our admiration. The precise cause of this phenomenon may be obscured, like every other phenomenon of congelation; but the effect is at once curious and pleasing; while, if we trace it up to that law, of which it is only an example, it will acquire a higher importance, and be found to be connected with a principle of vast magnitude in the world of unorganized matter; for the crystallizing process (and freezing is nothing else), seems to form the link between unorganic and organic substances; by the regular structure of its productions, mysteriously uniting crude matter with the vegetable and animal creations.

The pious Sturm, in speaking of this phenomenon, views it in a light different, indeed, but not less important, while his reflection equally applies to the other appearances of frost, which we have been examining. "Can an object be considered as little," says he, "when it furnishes matter for useful reflection? For my own part, I do not disdain to read, even on the frozen glass, a truth which may have a great influence on my happiness. Behold

the flowers which the frost has portrayed on the glass! They are beautifully and artificially varied; nevertheless, one ray of the noonday sun effaces them. Thus the imagination paints every thing beautiful to us; but, every thing which it represents as attractive in the possession of the goods of this world, is but a beautiful image which shall disappear in the light of reason. The importance of this lesson of wisdom was worth the trouble of stopping for a while, at the little phenomenon which furnishes it."

ELEVENTH WEEK-WEDNESDAY.

VII. FROST.-BENEFICENT CONTRIVANCES RELATIVE TO SNOW.

As the influence of cold is felt in the air, as well as on the surface of the earth, and indeed becomes more intense, in proportion to the elevation, it must affect the moisture which floats in the atmosphere. The rain-drops must freeze, and, when frozen, must be precipitated to the ground. Now, were this process to take place in the same manner as it occurs on the face of a lake or pond, and were the water in the clouds to be converted into solid lumps of ice, the most unhappy consequences would ensue, as may be inferred from the damage occasioned by a hailstorm, an occurrence which sometimes but rarely happens, as if to call our attention to the beneficent provision by which this calamity is usually obviated. The fruits of the earth would be destroyed; or, if the season of fruits was past, at least the branches and embryo buds of plants and trees would be shattered; birds on the wing, or on the perch, would be struck to the ground, stunned and dying; the more tender quadrupeds would receive their death-blow; and even the hardy races of animals, and man himself, would not escape material injury. None of these consequences, however, actually take place, be

cause the frozen rain-drops descend, not in the form of ice, or even usually in the less destructive form of hail, but on the downy wings of virgin snow.

Let us consider, then, the properties of snow, and we shall not fail to admire the wisdom of the provision. The vapour floating in the atmosphere is arrested by the cold, and is frozen; but, instead of running together, as might be expected, into solid masses, it unites with the nitrous particles, also to be found mingled with the air, and, forming a compound crystal, shoots out into beautiful feathery flakes. Whoever will take the trouble to examine one of these flakes with the aid of a microscope, cannot fail to admire the elegance and skill of its structure. He will observe many little sparkling crosses or darts radiating from a point, and branching off and meeting in all directions, so as to form hexagonal lines of much beauty, wrought apparently with the nicest art, and wonderfully fitted for passing, with a kind of buoyant and flickering motion, through the air, so as to drop, without disturbance, on the ground, spreading, as they actually do, a coat of dazzling whiteness, profusely, but gently, over bush and brake, waving lawn and towering mountain. It has been found by experiment, that snow is twenty-four times lighter than water, and that it fills up ten or twelve times more space, at the moment of falling, than the water produced from it when melted."* This is an admirable contrivance to prevent, or at least to modify, what would otherwise prove a great evil.

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Another useful property of snow has been noticed by many writers, and is verified by yearly experience. Being a very imperfect conductor of heat, it does not readily descend below the freezing point, and thus tempers the rigour of the season. Under its white covering, the earth remains of a moderate and equal temperature, and the bulbs and roots of plants are preserved from the ungenial influence of a severe sky. In consequence of the same slowness in the conduction of heat, the Arctic traveller * Sturm's Reflections, January 26.

can sleep, without much inconvenience, on his bed of snow, which is warm compared with the atmosphere he breathes; and, for the same reason, the snow-formed hut affords the Esquimaux no unpleasant abode.*

Nor must we forget to remark, with reference to the effects of snow on the soil, that the nitrous particles which it contains, are said to be of a fertilizing quality, and, as it gradually melts, these particles penetrate the earth, being carried to the roots of the plants, mingled with the water into which it is converted. Assuming the accuracy of this latter observation, we shall find abundant cause for admiring an arrangement, which, in various ways, converts an apparent curse into a blessing, changing that which seems to be an aggravation of this inclement season, and a source of sterility, into a protection from the cold, and a means of future fruitfulness.

But there is yet another arrangement, in reference to this subject, which must not be overlooked. When the weather changes, which it sometimes does very suddenly, the greatest inconveniences, and even calamities, would ensue, were the effect of this change to operate, as might, without experience, be expected, in producing an instantaneous conversion of the snow into water. If the frost were as quickly expelled from water as from the air, the moment that the temperature rose above 32°, the snow would pass into water as by magic, the ice would vanish like a dream from river and lake, and the rigid earth would, on the higher grounds, be in an instant converted into a swamp, and in the valleys would be overflowed, and swept away by mountain torrents. A very peculiar and remarkable property prevents these disastrous effects. In the act of dissolving, the water absorbs a quantity of heat, and retains it in a latent state; and, on this account, the melting process cannot take place till a sufficient quantity has been absorbed. This necessarily causes the process to be slow; and days, and even

* Whewell's Bridgewater Treatise, p. 90.

weeks, may pass away, after the thaw has begun, before the ice entirely disappears from our ponds, or the snow from our hills. The advantageous consequences of this retardation, are too obvious to require farther illustration; but it is of consequence to remark, that it is effected, not as a result of an ordinary and general law, but rather by what has been justly called the apparent violation of a law. A sudden stand, as it were, is made in the progress of the change. The alteration of temperature, instead of producing its ordinary effects, becomes, all at once, apparently feeble and languid in its operations; the heat, as it is applied, disappears, and its dissolving power is restrained within such bounds, as to render the process comparatively innoxious. A similar effect is produced in the boiling of water. At the boiling point, as well as at the thawing point, a sudden stoppage takes place, and the heat applied becomes latent, so as to preserve the water at that point, till it is gradually carried off in the form of steam. It is this property which renders water so useful in the various operations of the kitchen and the manufactory. If the whole volume of the water we employ were to be instantly converted into steam, when it arrived at the boiling point, which would certainly be the case, were it not for the peculiar property of which we are speaking, how much would be detracted from the usefulness of this most useful element !

Here, then, we have a wonderful modification of a general law, the beneficial nature of which is as manifest as the property itself is remarkable. Can we do otherwise than attribute it to the contrivance of an intelligent Creator?

The striking appearance of a landscape covered with new-fallen snow, and the effects produced on the lower animals by its fall, are thus graphically described by the poet of the Seasons:

"The cherished fields

Put on their winter robe of purest white.

'Tis brightness all; save where the new snow melts