others conterminous with it, and nearly parallel with respect to the direction of their component streaks. These appeared to verge to a point, but might be a common optical deception, depending on the laws of perspective,—at least, this is the received opinion of meteorologists respecting arched clouds. We are disposed, however, to think that the phenomenon cannot be always referred to optical deception; for we have more than once observed arched clouds, in various positions and directions with regard to the eye, which they could not have appeared in according to this supposition.

We continued to observe and admire those arched lines of cloud for several hours, namely, from noon till between four and five in the evening, and what was remarkable, though there was a light, but steady, breeze of wind in the direction of the arched lines, the form of the cloud remained nearly stationary and uniform in its outline. Now, are we to infer from this that a thin light stream of vapour spread over the whole extent of the horizon, and acted upon for four or five hours by a breeze of wind, would neither be evaporated nor moved from its position? The affirmative would be the natural inference; but Professor Daniell, in his excellent Essays on Meteorology, has endeavoured to account for the apparent stationary phenomena of clouds in so very ingenious and satisfactory a manner, that we hesitate not to adopt his explanation.

"The apparent permanency," says Mr. Daniell, "and stationary aspect of a cloud is often an optical deception, arising from the solution of moisture on one side of a given point, as it is precipitated on the other. No phe

nomenon is more common amongst mountains, or upon hills by the sea-side than clouds upon the summits which appear to be perfectly immoveable, although a strong wind is blowing upon them at the time. That this should be the real state of the case, is clearly impossible, as so attenuated a body as constitutes the substances of the clouds, must obey the impulse of the air. The real fact is, that the vapour which is wafted by the wind is precipitated by the cold contact of the mountain, and is urged forward on its course till borne beyond the influence which caused its condensation, it is again exhaled, and disappears. A slight inspection and consideration of the phenomena will be sufficient to convince any one of the correctness of this explanation. Reasoning from analogy, we may conclude, that the process which thus proceeds, under our eyes, upon the summits of the hills, likewise takes place on either side of the planes of precipitation in the heights of the atmosphere :-the vapour is continually condensed,—as continually re-dissolved in the act of precipitation, and the cloud appears to be unchanged and stationary.”—p. 124.

According to the electro-chemical theory of the formation of clouds, however, it would be affirmed that the cloud was really stationary and unchanged, in consequence of the equilibrium of the electrical influence produced by the primary developement of the cloud, from the union of the constituent principles of water previously existing in the gaseous state. It is barely possible to apply the ingenious reasoning of Mr. Daniell to this theory, and to suppose that, while the mist or vapour constituting the cloud is forming upon one side, the water is simultaneously decomposed on the other side.

We are still too much in the dark with respect to the principles that regulate atmospherical phenomena, to decide upon the precise effects of electricity; but supposing the theory alluded to has some foundation in nature, we may be tempted to proceed a step further, and connect it with the nearly allied influence of magnetism. Indeed, without some such power acting upon the light and moveable streaks, and tufts of vapour, which form what we call wane-clouds, (cirrus, HOWARD). We cannot devise any satisfactory explanation of the appearances which may so frequently be observed; for if the wind were the sole agent in determining their forms and positions, they ought always to stream in the direction of its current, as we see is uniformly the case in the analagous instance of smoke. In the case of waneclouds, however, they as frequently appear to cross or lie obliquely to the current of the wind which blows in the plane of their stratification as the contrary; and sometimes they may be seen in positions simultaneously so dissimilar, that it seems difficult to refer the direction of any particular tuft or streak to any known agent. As an instance of this, a few days after the occurrence of the preceding arched wane-cloud, we observed a wane-cloud with the wind, which was easterly, in the general direction of the streaks, but shorter crossing streaks occurred almost at right angles to the current of the wind, while there were long streams extending over half the visible horizon, divaricating very considerably from the parallelism of the line which marked the direction of the wind. Might it not be, that some at least, if not all, of the lines of cloud were in a position corresponding with the what mathematicians call the

resultant of two forces; which in this case, we assume to be the current of the wind, and terrestrial magnetism? So far at least, we are certain, that those long lines of wane-clouds very frequently lie in directions corresponding or nearly corresponding with the magnetic meridian; and if magnetism has no influence over them the coincidence must be confessed to be singular and unaccountable.

It would be wrong, however, to venture upon any positive assertion of this theory or rather speculation, in the deficiency of well ascertained facts; but from the analagous arrangement between the wane-clouds figured above, and the streaks of the Aurora Borealis, which is also supposed to be connected with magnetism or electricity, we think, that farther investigation may elucidate the dependance of the phenomenon on the same causes. The Aurora Borealis indeed, is almost always in the direction of the magnetic meridian, while the wane-clouds in question, so far as we have remarked, are more under the influence of the current of wind blowing in the plane of their stratification.*

CAT WHICH CAUGHT SWALLOWS ON THE WING. -We have frequently remarked the surprising rapidity with which beasts of prey pounce upon their victims, but the most striking instance which we recollect of, this was that of a cat, who caught swallows on the wing. It was in the spring, when insects, in consequence of the cold, fly low, and of course the swallows are forced to hawk for their prey by skimming the surface of the ground. The wily cat, taking advantage of this, stretches herself upon a sunny grass plat, with her legs extended * J. Rennie, in Mag. Nat. Hist. vol. i.

as if she were dead; the flies collect about her, as flies always do when they can find any animal as patient as my uncle Toby to endure their buzzing and tickling. The simple swallows, dreaming of no harm, and thinking they can here make a good meal,-dip down from the barren air,-dart with open bill upon the flies; when puss, perceiving her prey within reach, makes a spring like a flash of lightning, and strikes down with her paw the poor thoughtless swallow. The best marksmen know how difficult it is to shoot a swallow on the wing; but the cat found her patience, cunning, and rapidity well rewarded by her unerring success whenever a swallow ventured within her reach.

DIFFUSION OF SEEDS.-The economy of Providence in distributing seeds, may now be remarked in those of the Dandelion (Leontodon taraxacum) which are every where to be seen floating about on the air, supported by their feathery down. It is not to be supposed, that half of these ever fall upon spots favourable to germination; but when so great a number of them, and of their congeners of the class Syngenesia, are scattered about by the winds, it almost raises the chance to certainty, that some of them will fall in spots where before there has been none, or only a scanty vegetation: on the tops of walls, for instance, where a thin stratum of soil has been formed by the decay of the winter crop of mosses. The process of the formation of such soil, is exceedingly interesting, and may be observed on a small scale even in cities, on brick or stone walls. First, there is the green incrustation called byssus, by Linnæus, but recently proved to be the primary germination of several species of mosses, such as polytricha and tortula. When this

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