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in consequence of the nitrous salts which it is supposed to acquire by freezing'. But it appears from the experiments of Margraaf, in the year 1751, that the chemical difference between rain and snow-water is exceedingly small; and that the latter, however, is somewhat less nitrous and contains a somewhat less proportion of earth, than the former; but neither of them contain either earth or any kind of salt, in any quantity, which can be sensibly efficacious in promoting vegetation. Allowing, therefore, that nitre is a fertilizer of lands, which many are, upon good grounds, disposed utterly to deny, yet so very small is the quantity of it contained in snow, that it cannot be supposed to promote the vegetation of plants upon which the snow has fallen.
On the uses of snow we add some further particulars, which the researches of modern science have brought to light. All those who inhabit parts of the earth exposed to snow, agree in considering it as one of the means employed by nature to give plants more strength, and make them expand with more vigour. Several are even persuaded that winters, producing no snow, presage a bad harvest, and a feeble state of vegetation; and they ascribe its influence to the salts, which they say exist in congealed water. That, after a very severe and cold winter, plants should be stronger and more active in proportion as they may have been covered with snow, is proved by the experience of every one engaged in agriculture. The cause is simple and natural. All plants are capable of supporting cold in a greater or less de
THOMSON falls into this popular error.
Thro' the blue serene,
gree. There are some which cannot be exposed to the temperature of melting ice without perishing, while there are others in which the most intense cold makes no alteration. Each plant has certain limits as to its resistance of cold, a certain temperature beyond which it cannot go, without the danger of being frozen and destroyed. The earth, as is now well known, has heat accumulated in its interior parts: this heat is perceived in all subterraneous places of sufficient depth to prevent the external heat or cold from entering. Snow is a bad conductor of heat, cold penetrates it with difficulty; and its temperature, when it melts, is zero. When the earth is covered to a considerable depth with snow, the cold of the atmosphere, in contact with it, tends to cool its mass; the internal heat of the earth tends to warm it. Throughout the mass of snow there is a strong contest between the heat and cold; a portion of the snow is melted and carried to zero, the medium temperature, wherein the plants are situated.
The snow has the properties of keeping the plants it covers at the temperature of melting ice; of preserving them from the influence of a greater cold; of supplying them with continual moisture; of preventing a great number perishing, and still more from languishing; and, consequently, of im• parting more strength and vigour to vegetation. It appears, then, that we may explain a part of the influence snow has upon vegetation, without having recourse to the salts or nitre which it is said to contain, but which analysis and experiments have proved do not exist. It has also been de monstrated by experiment, that snow is oxyge nated water; that, in the germination of seeds in particular, the presence and contact of oxygen are absolutely necessary for the plant to expand; and
that, in proportion to the abundance of oxygen, the more rapidly the seeds will grow.
Most plants, permitted to attain their perfect maturity, shed on the earth a part of their seeds, which, thus abandoned and exposed to the action of cold, are covered and preserved by the snow. At the same time they find in the water the snow produces by melting, a portion of oxygen, which has a powerful effect on the principle of germination, and determines the seed, which would have otherwise perished, to grow, to expand, and to augment the number of plants that cover the surface of the earth.
A very considerable number of the plants we have the art of appropriating for our nourishment and wants, are sown from the end of September to the end of December. Several of them germinate before the cold commences its influence upon them, and changes the principle of their life. The snow which covers the rest, acting on their germs by its oxygenation, compels them to reward the trouble of the farmer and gardener, and multiply the quantity of useful productions.
The influence of snow on vegetation cannot be better summed up, than by saying that, in the first place, it protects the plants and the seeds from the violence of the frost; in the second, furnishes them with a continual moisture; and in the third, makes a greater number of seeds to germinate'.
What themes of grateful adoration does the discussion of this subject suggest! But I will leave my readers, in expressive silence,' to
muse the praise' of the great Creator; and shall conclude with that beautiful emblem, under which
See Gent. Mag., vol. lxxxiv, part 2, p. 544.
he is supposed, by the prophet Isaiah, to represent the salutary efficacy of his divine word: As the rain cometh down, and the snow from heaven, and returneth not thither, but watereth the earth, and maketh it bring forth and bud, that it may give seed to the sower and bread to the eater; so shall my word be that goeth forth out of my mouth: it shall not return unto me void, but shall accomplish that which I please, and it shall prosper in the thing whereunto I sent it?
ON WINTER IN THE POLAR REGIONSA
Our infant Winter sinks,
Divested of his grandeur, should our eye
There Winter, armed with terrors here unknown,
WINTER, in our temperate regions, exhibits very few phenomena, in comparison with what is visible in the arctic circle. Thomson, therefore, has judiciously enriched his noble conclusion of the Seasons with all the circumstances of pic
turesque beauty, or terrific grandeur, that could be borrowed from scenes far remote from us. The famished troops of wolves pouring from the Alps; the mountains of snow rolling down the precipices of the same countries; the dreary plains over which the Laplander urges his reindeer; the wonders of the icy sea; and volcanoes flaming through a waste of snow; are objects selected, with the greatest propriety, from all that nature presents most singular and striking in the various domains of boreal cold and desolation.
Among the wintry objects which delight the mind by their beautiful and picturesque appearance, we may often observe the effects of the hoarfrost, or of the dew or mist frozen. This adheres to every object on which it falls, and produces figures of incomparable beauty and elegance. Every twig and blade of grass is beset by it with innumerable glittering pearly drops, or silver plumage, beyond the skill of any artist to imitate. These appearances are still more striking, the farther we proceed to the north. It sometimes happens, that a sudden shower of rain falls during a frost, and immediately turns to ice. Philips, in his Epistle from Copenhagen, has given a beautiful description of such a scene: a description which forms as fine a winter piece as we have ever had from the schools of the most exquisite painters:
Ere yet the clouds let fall the treasured snow,
And heightened every object to my eyes: