DECEMBER.

MIGRATION of Birds to THE MOON.-In a scarce anonymous tract, published by Crouch in 1703, written to expound the text "The stork in the heaven knoweth her appointed times, and the turtle, and the crane, and the swallow, observe the time of their coming,"* it is maintained with no little ingenuity, that our migratory birds retire to the moon. The arguments are much too long to be mentioned here, but we think our readers may be amused with the "Postscript" of the author, who is designated on the title page-" A person of learning and Piety."

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Concerning," he says, "the great distance between the moon and the earth, if any one shall still remain unsatisfied, I have only this to offer to his consideration, whether there may not be some concrete bodies at much less distance than the moon, which may be the recess of these creatures, and may serve for little else but their entertainment. Thus, we see many rocky islands in the sea, that are of no other manifest use, than for sea-fowls to rest and breed upon, and these are, therefore, commonly called gull-rocks. Now, if there be such globuli or aetherial islands, they must be supposed of such magnitude only, and set off at such distance, as their

* Jeremiah, viii. 7.

reflexive light may not reach home to our earth, (though perhaps they may serve to illuminate our atmosphere) else they would e're now have been discovered, and yet no farther off, than these birds may conveniently arrive unto them in such time as may be most convenient to allow them. This I do suggest, because it is hard for me to persuade myself, that they come from any other part of this earth, as it is to persuade another, that they come from the moon; and, therefore, if the moon will not be allowed, some other place must be found out for them."

It must be confessed, that however fanciful this may appear, it is more rational and plausible than the opinion maintained by many distinguished naturalists, that swallows hybernate at the bottom of lakes and rivers, among the mud.

EVERGREENS. The Strawberry - tree (Arbutus unedo), one of our prettiest evergreens, now shows both fruit and blossoms, at the same time, in situations favourable to its growth; for it does not blow freely in every exposure. In the neighbourhood of London, for example, it seldom fruits well, while in Ireland, of which indeed, it is partially a native, it may frequently be seen loaded with its crimson berries, and beautifully lucid flowers. Evergreens, it may be remarked, at least those in cold latitudes, are furnished with strong, tenacious, viscid juices, which are usually most abundant also (in firs for example) at the base of the leaves, and this serves to protect them from the effects of cold and damp. Within the tropics, these glutinous juices are less required, though there all trees are evergreen, and as evergreens are usually darker in tint than deciduous plants, the tropical forests never exhibit the endless variety of

shades which are so much admired in temperate climates.

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TORPIDITY OF SWIFTS, AND SUBMERSION OF SWALLOWS. The experiments of Spallanzani and Reeve, render it very improbable that any species of bird should become torpid. The rapidity of the circulation of the blood in birds, is a circumstance which strongly opposes the supposition of torpidity occuring amongst them a slow circulation being one of the most indispensable conditions.

Few naturalists of any note, we suppose, now believe in the submersion of swallows under water during the winter, a circumstance not long ago believed in by Naturalists of the highest name, such as Daines Barrington, Klein, and even Linnæus himself, who talked of their assembling on reeds, and on the banks of rivers, and singing their swallow song before they dived. But were this so, our fishermen could not fail to drag some of them from their hiding places with their nets, a thing which has never been known to happen. Independent of this, their physiological structure renders it impossible for them to exist for many months under water; and it is contrary to all analogy in the class of birds-for not even the sea-fowl, which live constantly in the water, are able to remain any time submerged. To put an end at once to the controversy, our European swallows have been repeatedly seen crossing the Mediterranean towards Africa, at their autumnal departure, and M. Adauson, who was too good a naturalist to be easily deceived, found them during winter in Senegal.

NATURE OF BITUMINIZED FOSSIL WOOD.-The most recent investigations of our best chemists and geolo

gists, tend to confirm what is here said, in opposition to the universal popular opiniou. Dr. Watson proved, that even the lightest wood will sink when floated in water, till it is thoroughly saturated with moisture. When trees, therefore, fall in the water of bogs they soon become thus saturated, when the chemical process of bituminization commences, by which the original colour of the vegetable matter is converted into a deep brown. Sometimes the texture is changed, as in the process of putrefaction, the substance called peat being the result; but in the case of trees, the original fibre of the wood is most frequently preserved, at the same time the whole is imbued with the bituminous matter, and this being always very inflammable, similar to pine and fir-wood, it has given rise to the opinion that it is actually fir. There can be no doubt, that fir may be found under these circumstances in countries where pine-forests grow; but in Derbyshire, Cheshire, and Walmer Forest, the existence of fir in the recent bog-formations, must be very problematical. The subject, however, still requires more minute investigation than it has hitherto received.

PRESERVATION OF TREES IN WINTER.-In ironfounderies, such as the foundry for cannon at Munich, it is customary to stir the melted metal with a branch of green oak, and notwithstanding the great heat of the metal, the green wood is not affected deeper than about the twentieth part of an inch. This striking fact is explained from the non-conducting power of the sap, and upon the same principle it is that the bodies and branches of trees, not having the covering of snow which the roots have, are protected from the operation of cold,

by their sap increasing in spissitude, and of course in non-conducting capacity, as the winter approaches. On similar principles, we may account for the preservation of various kinds of fruit.

RULES FOR THE WEATHER.-A wet summer is always followed by a frosty winter, but it happens occasionally that the cold extends no farther. Two remarkable instances of this occurred in 1807-8, and 181314. With these exceptions, every frosty winter has been followed by a cold summer.

The true cause of cold, or rather the direct cause, is to be found in the winter excess of west-wind-every winter, with excess of west-wind, being followed by a cold summer; and if there is no cold before or during a first excess, then a second excess of west-wind in winter occasions a still colder summer than the first. It also appears by repeated experience, that cold does not extend to more than two years at a time.

Again, if the winter excess of east-wind be great in the first instance, the winter will be mild, and followed by mild summers; while the summer excess of east-wind is itself in the first instance always mild, but uniformly followed by cold winters and cold summers, which continues more or less for one or two years, according to circumstances.-Mackenzie,-Syst. of the Weather.