A property of water, which, however, unlike the former, it shares with all other liquids, is, that when it freezes it gives out a large quantity of heat; and that conversely, in order that ice may melt, it must obtain, from some other source, a quantity equally considerable. Consequently, water freezes and ice melts very slowly; and that it should melt thus slowly, is of essential importance in animated nature. If in spring or summer, when vegetable life is in activity, when the development of leaves, of flowers, and fruit, is at its greatest energy, end all the vessels of the plant are distended with its nutritious juices, were it suddenly exposed to cold, the sap would be frozen, and by the expansion of the ice the vegetable tissues torn to pieces, and the plant killed. In the thin extremities, as in the leaves, such is the effect of the frost of a single night; but as the fluids, yielding but gradually up their latent heat, solidify very slowly, the injury does not extend so far as to be beyond the remedial powers of the plant itself. In another way, however, the peculiar latent heat of water is of still more importance. If there was no large collection of water on the globe, the change of seasons would be amazingly more rapid and more remarkable than they at present are. A change in the direction of the wind, the alteration which a few weeks should effect in the position of the sun, would transfer us from the depth of the severest colds of winter to the summer heats. These colds and heats would also be much greater than they at present are, and an approximation to this actually occurs in countries far distant from the sea. The central districts of Europe and of Asia have what are termed continental climates to distinguish them from ours, which is called insular. Their summers are hotter, their winters are much colder, and the spring and autumn seasons of passage, which with us might be said to occupy most of the year, are in those countries of only a few weeks’, or even a few days’, duration. In fact, when on the cessation of summer the first cold winds tend to bring on the winter, and to bind up our lakes in frost, the first portion of water frozen becomes, by giving up its latent heat, a source of warmth which tempers the chilly air, and retards its action on the remainder. The water freezes thus very slowly. The vegetables, and certain classes of animals, feeling the cold of winter thus gradually coming on, prepare to meet it without injury. The motion of the sap in the one, that of the blood in the other class of living beings, becomes slower, and, dropping its leaves and fruit, the tree retains but its firm trunk, within which its energies are preserved for the ensuing season; whilst the hedgehog, the viper, the frog, and other animals, retire to their hiding-places, and in a state of almost lifeless stupor remain until the warmth of the succeeding spring calls them to renewed existence.