prieter, that it be felled in winter, when the grass and corn is off the grounds, than in the spring itself. And the officers designed for that purpose may buy all their timber under the conditions of its being felled in winter, after the bark has been taken off in the spring in due time. Extract of a letter from Mr. Anthony Van Leuwenhoeek to the Royal Society, concerning the difference of timber growing in different countries, and felled at different seasons of the year.

"As to the difference of timber felled in winter from that felled in summer, the common opinion is, that the former is stronger and more lasting, as being more close and firm; but his own opinion is, that there is no difference, except in the bark and outermost ring of the wood, which in the summer are softer, and so more easily pierced with the worm. Wood consisting of hollow pipes, which both in summer and winter are full of moisture, they do not shrink in the winter, and therefore the wood cannot be closer at one time than another, for otherwise it would be full of cracks and clefts. The sudden and unexpected rotting of some timber, he conceives to proceed from some inward decay in the tree, before it was felled; having observed all trees begin to decay at first in the middle or heart of the tree, though possibly the tree may staud and grow for near 100 years afterwards and increase in size all along."

He says he was once of opinion that trees growing in good ground, but increasing slowly, were the best and strongest timber; and that those trees which in few years grow large were the softest and brittlest, the contrary to which, on enquiry of experienced workmen he found to be true, and instances in elm of 80 years growth, which was eleven feet in circumference, and proved excellent tough timber.

The age of trees is to be known by the number of rings to be seen when the tree is cut across, in each of which is one circle of large open pipes, now the fewer there are of these large pipes, the stronger the timber is; hence those trees that make the largest growth in a year must be the closest and strongest; and therefore those trees that grow in warm countries grow fastest, and are the best and toughest timber, which he confirms by Riga and Dantzic oak, which is of slow growth and proves spongy and brittle timber; whereas the contrary is observable in English and French oak, which grows faster, and is excellent timber.

THE WEATHER.-1. Its Changes; 2. The design of the Circular Hurricane; 3. The Variable Winds of the North Atlantic.—Considered by Stormy Jack.

THE general natural system of the variations of weather throughout the world, appears so complicated, that, considering the lapse of ages which have succeeded the first essays to explain the seeming mystery, it is not a matter of wonder that the idea of its being beyond the intelligence of man to fully comprehend, should have been entertained. The apparent contrarieties, anomalies, and observed capriciousness with which its workings are controlled, seem to defy the utmost ingenuity of the most indefatigable meteorologist to account for satisfactorily. What faith

then is to be placed in the predictions of a Moore, a Murphy, or any other divining almanac computor?

The changes often follow in such rapid succession as to be truly astonishing; yet how few in the busy round of human occupations, duties, pastimes, and pleasures, allow but an instant of thought on the causes of such phenomena? But "thinking men" or such as are imbued with a spirit of observation, know that as a whole; that is to say, in the aggregate results, the system of nature is, and cannot be admitted to be otherwise than perfect. In the details, in the periodic returns, indeed, we are apt to imagine that we detect irregularities; and hence the source of the perplexities which assail those who deal only with the abstract question: to our wonder, however the philosopher, the man of enlarged views, who surveys the whole panoramic scheme, dealing first with particulars, next, amplifying into generalization, and finally calculating the amount of evidence deducible from facts, informs us that a balance is always struck with precision, in a lunation, a season, or a year. And it has been thought that a recurrence of similar weather takes place at long intervals, such as in the period of nineteen years, or what is scientifically termed a lunar cycle; or, in twenty-eight years, which is the solar cycle.

Our theories appear to be more or less faulty even in the present state. Nothing else, indeed, could be expected. The period required to draw just conclusions, and the close and incessant habit of observation necessary for obtaining data for that purpose, are so urgent, that even though an individual could be found possessing perseverance and determination enough to afford his undivided attention to the object; his entire life would be considered too short, to bring the whole matter into a state approaching toward perfection. But by a wise distribution of labour, which might be greatly lessened by a universal association of enlightened and scientific societies of Europe and America, and their Colonial associates in other parts of the world, so that the duties of observation and registering may devolve on many, instead of being dependant on one or two only, there is scarcely a question that meteorological science, which has been so long neglected, would very soon begin to ascend toward that station to which it is deservedly entitled.

It may be observed, however, that upon the whole, we possess a tolerable clear and satisfactory outline of that portion of the general system which embraces the action and apparent causes of most of the particular winds-1. Those which are so far steady throughout the year, as to be deemed perennial. 2. Others so nearly regular in their change as to be termed alternating. 3. Those whose recurrence are looked for with a degree of certainty, and are called periodic. 4. Land and sea breezes which are designated reciprocal. 5. Circular storms, or hurri

canes.

With respect to the uncertain winds, or those which have obtained the name of general or variable, as much could not have been said or advanced hitherto, and indeed scarcely yet, as the inquiry has only began but a very short time.

The old phantasie of these winds being occasioned by the reaction of the atmosphere from the rotation of the earth, will, probably, give place

to a more rational system, which has some better support than hypothetical reasoning, and abstract ideas to uphold it.

Of the causes of calms at sea, too, we know little or nothing. Of their occurrence often in the very heart of the perennial winds; and sometimes preceding gales, but oftener after them, we have no scientific treatise. Indeed there is a gap in our general literature which requires to be filled up by some competent writer, and which work would yield, in the interest it would create, to no other scientific composition; we allude to the phenomena of the ocean.*

From time immemorial lunar influence has been enlisted as an agent in the production of the changes of weather; such is, indeed, at the present day, all but universally acknowledged; yet to those who have devoted close attention to fact and circumstances, it would appear to be very questionable. Nevertheless, the general opinion does not create surprise in them, the supposition being extremely natural, and readily presenting itself to the mind as a very apparent solution of the physical phenomena of which we are speaking. The consideration that the tides of the ocean owe their origin to the moon's attraction; and changes of weather not unfrequently happening at the change of the satellite's phases, could not fail of becoming otherwise than remarkable, and to press upon the mind of even the most superficial observer, the idea that the planet also exerted an influence on the fluid air.

But, if this were true, there ought to be at least a corresponding regularity in the times of change, allowing for a want of minute precision of effect, from local external causes. Now, all those who have paid attention for a lengthened period, and daily, and hourly, recorded the circumstances as they occurred, are aware that no such thing can be admitted.

Without referring to more distant observations which have been pubished, that bear upon this point, we may, perhaps, advantageously Instance the north-easterly breezes, which have been prevalent with very trifling interruption from the 17th of February to the 3rd of April, which exceeds a lunation and a half. It seems improbable, therefore, that the moon's changes have any direct, or sufficiently powerful influence over the atmosphere, as her attracting power has over the waters of the ocean.

We give here the result of these slight changes for the satisfaction of the reader. On the 17th of February, 1840, the wind shifted from the south-westward to the eastward, the full moon was on that day. On the 22d of March the wind veered from the eastward to the northward and north-west, and back to the north, four days after the full moon; after vacillating thirty-six hours it fixed in the north-east again. On the 30th it veered to the south-west, four days after the last quarter.

* Considering the manifest utility of such a work in the hands of youth, intended for the Naval profession, which no expense should be spared to bring to the highest possible state of perfection, I really think the Government might advantageously offer a premium, for the best composition on this subject. There is little doubt of such a work meeting a very extended sale, if the price fixed should be easy.-S. J.

The vacillation from north-castward to south westward and back, continued until the 21st of May, when the westerly winds set in steady.

On the 1st of April, it backed to south-east and east, one day preceding

the new moon.

Here we see no corresponding regularity shown; although from the approximation there appears to have been some slight, but indirect, influence exerted, which perhaps may be owing to an alteration in the barometric condition of the atmosphere consequent on the tides, and in connection with the electrical state of the air. Besides, if the lunar influence existed, ought we not to expect that the force or strength of the wind, as well as its variation, would follow a similar law of gradation which the tides observe in their height, according as the satellite is in her perigee or apogee? I have known the easterly winds to continue for twelve or fourteen weeks with little variation in strength. If the moon really exerts any influence on the weather, as it is said to do on the human frame and mind, as also on vegetables, certainly we have not yet succeeded in making this plain, by pointing out the interfering influences which operate in divesting it of a regularity of action.

Indirectly, perhaps, by means of the tides, it may be admitted that the moon's attractive power has a partial effect on the atmosphere; but unquestionably it does not work alone, and without auxiliaries seems to be powerless. The change of weather, induced by the spring-tides, appears to be principally confined to the directing of the vapours, incumbent over the ocean, iuland by fluvial attraction; the increase of wind which takes place at such times, being, probably, attributable to electrical action. It seems apparent that the barometric state of the atmosphere must be affected in channels and estuaries where the rise is considerable; it is, therefore, probable, that the agents act in unison when changes occur; and that no alteration takes place when singly exerted. This is the natural conclusion, or otherwise we should experience a regularity in the changes which would leave little to be sought for; but as the variations of weather are not always coincident with the reciprocations of the tides, at springs and neaps, and we can obtain no means for anticipating the simultaneous action of the different agents which

produce the effects, the prediction of what will happen, seems to be, at present, a matter which our intelligence and acute observation cannot arrive at. But I do not mean to pronounce it as utterly impossible, although we may have little expectation of its speedy realization.

A remarkable recurrence of rain takes place in the north part of Somerset during spring-tides, and the prevalence of southerly and southwest winds, after a lapse of about four or five hours, from high water in the Bristol Channel. I was a long time puzzled to account for this circumstance, but at last the idea struck me spontaneously, when not thinking of the subject, that the difference of time in the high water of the Bristol and English Channels was the cause; I have, therefore, no doubt that the recurrence of the showers is occasioned by the flood being later in the former than the latter, the elapsed time agreeing, and the direction of the winds being such as to convey the vapours across the land.

Lord Bacon says that, a man would do well to carry a pencil in his pocket, and write down the thoughts of the moment. Those that come unsought are commonly of the most value, and should be secured, because they seldom return. The spirit of this plan I have long adopted whilst musing on any particular subject, and, indeed, sometimes without fixing the ideas on any. Such thoughts as arise, and appear to be useful in the elucidation of any point; and these often present themselves spontaneously, I immediately write down, having always at hand, whilst in the house, pen, ink, and paper for that purpose. In many instances I have set down to reason out facts, yet without success; but, have found what I had been puzzling myself about at a moment when the mind was in a quiescent state, without the shadow of a thought flitting across it; and the idea has come suddenly as though it had been produced by some magical agency, which like the effect of the solar ray upon sympathetic paper, leaves a visible trace, that unless immediately attended to soon vanishes. Perhaps all persons, except the most giddy and volatile are susceptible of such impressions, but it is probable that those who are habitually disposed to thoughtfulness, and grapple with any subject in downright earnest, are more likely to be accommodated by this strange, if not mysterious impulse of the mind.

In two years attentive register of the winds, and the variations of weather, I have some remarks on the facts as they occurred, which would seem to confirm the pilots' and fishers' observations on this head.

The slight interruptions in the steadiness of the easterly winds of the spring, to which I have alluded, in the south-western part of England, may probably, in some measure be thus accounted for. I consider the changes as mainly, if not solely, dependant on the temperature of the air over those parts of the island bordering on the Atlantic; and that the westerly winds which effect the interruption, are regressive. The outline of the process is as follows: an unclouded sky, with a low thin haze, usually attends the easterly wind, and the sun's rays being unobstructed, and a vast portion of the land's surface being newly ploughed up, the absorption of heat is thereby facilitated. The luminary's transit over the equator necessarily increases the temperature to the northward; and this heat of the lower atmosphere of the land, slowly, but progressively increases towards a maximum over that of the