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water pounded, or with snow. This might be quoted in favour of the doctrine "similia similibus curantur," but is quoted to show how experience has proved the benefit of preventing sudden reactions from the effects of cold in the human body. In like manner experience has shown that the life of the plant, or the vitality of its leaves, may be preserved, if, by shielding it from the rays of the sun, a sudden reaction is prevented. For this reason gardeners, before sunrise, take care to cover up the shrubs and crops they wish to protect when an early and unexpected frost has "bitten" them; for they say "the sunshine will do more mischief than the frost."
The temperature of vegetation is above that of the atmosphere in winter, unless the plants are completely frozen, when their life is suspended in some cases, in others destroyed. But this supply of vegetable warmth is sufficient to resist cold to a greater extent than would be supposed; a covering of woollen or of matting being found, in practice, sufficient to preserve plants from injury by very long and severe frosts.
When, nevertheless, a succulent plant, the cells in whose stem and leaves are filled with fluid sap, is so situated as to be fully under the influence of freezing air, a complete death of the plant ensues. I have before explained that when water is cooled to within about ten degrees of the freezing point it ceases to contract, and that, unlike other substances, in passing from a fluid to a solid state it expands considerably. The sap of the plant consists for the most part of water, confined in the passages and cells of the tissue in the leaves and stem; and this fluid, when frozen, expands and lacerates the vital organs so as totally to destroy the life of the plant. If the leaves are placed upon the hand they will be found to be soft and pulpy, as if they had been boiled; so complete has been the destruction of the minute cells of which their tissue was composed.
Another phenomenon associated with the advent of frost was long the theme of superstitious and ignorant wonder. The pedestrian who crosses a meadow in the middle of the day after a frosty night will see, occasionally, the print of footsteps apparently burned into the sod. The grass may be two or three inches in height throughout the meadow, but where these mysterious footsteps have been, the herbage seems singed or seared close to the earth. Before people knew better, and while religion was more completely in the fetters of unreasoning superstition, good folks were wont to point to these footprints as the physical proofs of the existence and personal wanderings of the impersonation of evil. But the "old wives' tale" fell a victim to the progress of science, which discovered how these mysterious footprints could at will be produced by the best of men, if they walked over frozen grass in the early morning, and proved that the supposed Satanic agency was quite unnecessary. The blades of the grass, being completely frozen, were as brittle as the ice which filled and expanded their cells, and consequently snapped off under the pressure of the foot. When the sun rose the greater part of the field was exposed very gradually to its rays, and the grass, therefore, suffered little in general; but the broken blades were only the more completely withered and blackened, because they would be sheltered by the surrounding herbage till the sun was high in the sky, and his beams of considerable power.
The year has now run its course, and the succession of the seasons has been accomplished. The earth has carried us through the immensity of
space, completely round the great luminary on whose beams days and seasons depend, under the guidance of Him "who set the stars in the firmament, and guideth the wanderers of heaven."
Our literary circle of phenomena is also completed; and we lay down our pen as to our readers we sigh-Farewell!
"These, as they change, Almighty Father, these
Thy beauty shines in autumn unconfined,
And spreads a common feast for all that lives."-THOMSON.
LONDON: PRINTED BY H, TUCK, 16 & 17, NEW STREET, CLOTH FAIR.