berance, the tremendous gales which had so lately agitated the atmosphere, had swept the leafy honours of the grove with ruthless hand. Now hush ed to silence, the breeze scarce ruffled the unbroken surface of the water, and the foliage, which thinly hung in scattered fragments on the majestic pine, which proudly towered above his fellows, formed the sure presages of approaching change in the revolutions of the season.

I involuntarily sunk into reverie, connected with the economy which fructifies and corrects the phenomena of our atmosphere. How complicated and grand, yet how simple and harmonious are the principles upon which animal and vegetable life are support ed and renovated on our terrestrial globe! While we admire the incalculable uses which are attendant upon the tempestuous eddies which visit, at certain intervals, the atmosphere we inhale, we are no less constrained to speculate upon the wisdom and contrivance by which they are philosophically educed. That refulgent orb, the prodigious source of life to unnumbered myriads of creatures,-the mighty image of an all-creative and all-vivifying power, is ordained to operate in a twofold manner upon our globe and its atmosphere.

While its light irradiates, and its heat engenders vitality, it is also employed in regulating the winds; and to its sole instrumentality Naturalists have ascribed the periodical recurrence of excessive storms when the sun (to us) enters certain constellations of the Zodiac. Particular tracks in our atmosphere experience an excessive rarification from the sun's continued ac tion;-these rarefactions immediately produce currents, which rush through the fields of ether in various directions, and with different degrees of impetuosity, in proportion to the force with which the rarefying or compressing power acts.

Hence the acceleration of certain portions of the aerial fluid, which, whether in its effect it refresh and invigorate our bodies in the summer's breeze, or tear up the oak of the forest with its impetuous gusts, is only so many modified effects resulting from the same cause.

This fluid, which we call atmosphere, not only subserves the purposes of our existence in innumerable

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ways, but is ordained to form the basis of high and varied enjoyments in our intellectual life. Its chemical uses in sustaining vitality in the ani mal and vegetable kingdom, and its share in the decomposition and recomposition, and mutual action on each other, of all material bodies, have ever formed a source of interesting study since intelligent mankind have learned to investigate the treasures of that ample cabinet upon which they vegetate. But the phenomena with which it stands connected with the science of Optics, and through which it has relation to our moral and intellectual nature, forms a topic of disquisition not always, perhaps, duly appreciated. Atmosphere, in its various forms of tenuity, is supposed to extend around our planet about thirty or forty miles more or less from its sur face; and the other planets of our system have been found from experiments to possess, several of them at least, this phenomenon in the economy of wisdom for preserving life and heightening enjoyment. Unlike the vortices of Des Cartes, however, this elastic fluid accompanies, instead of directing, the motions of the planets in their respective orbits. The ingenuity and research of the renowned founder of the Cartesian school (who taught that all bodies in space did, in truth, perform their revolutions through the instrumentality of this fluid,) only led him in pursuit of an ignis fatuus, which had proved the source of fatal errors to mankind, had not the superior sun of Newton's intellect quickly afterwards arisen to dispel the illusion. His infinitely more beautiful theory of a gravitating principle, which mutually imparts and receives motion and regularity to the great bodies of our system, dispelled the fallacy, and assigned to atmosphere its proper office in the spheres. The fluid which constitutes atmosphere is now known to fulfil its proper offices in the universe, and instead of constituting a propelling power, as taught by Des Cartes, attends them in their revolutionary course as a genial satellite-a provision at once simple, and admirably happy in fulfilling its diversified purposes.

We see that vitality in animals and vegetables is presently extinct when deprived of the sustaining and vivifying principle of air,-it is no less cer

tain that sounds in all their innumerable modifications, must be also extinct, if a perfect vacuum prevailed on the surface of our globe. The theory of intelligible language which, per haps, imparts to life its highest pleasures, could not, under our present economy, exist but through the instrumentality of the fluid in which we move and breathe. The tympanum of the ear, (no longer agitated by the concussions impressed upon the floating particles of air, and which by re-conveying certain infinitismal vibrations to the brain, produces the sensation of hearing,) would, as an organ of sense, for ever remain useless; while in another important sense, by which we inhale a thousand odoriferous scents, wafted upon the summer's breeze, we should be equally destitute of impressions, as without the assistance of the fluid, called atmosphere, to serve as the medium of conveying the impression, it is impossible we should ever receive it. Absolute nihility can form the basis of conveyance to no impres

sion.

But in another of the faculties of sensation, one of the noblest and most useful, which stands most intimately connected with the intellectual faculties, that of vision, the effect would be as signally striking. The sublimest phenomena, perhaps, connected with our atmosphere, is the universal diffusion of light, and the equalized and soft radiance which pervades every space throughout our globe, not excluded from the sun's light. These effects are very well known to Naturalists, but are apt to be overlooked by common observers. Were it not, how

ever,

for this rare and subtle fluid which encompasses and rises to a considerable height above us, light, as emanating from the resplendent luminary which forms the centre of our system, as it could never answer the purposes of vegetable life, so would form an incomparably less cheerful and perfect medium of invigoration to the myriads of creatures which move on the surface of our planet. All would be contrast in the expanse above us. The mild diffusion of his splendour, the radiant glories with which the beams of the sun are reflected to human optics, would no longer exist; a continued blaze of ineffable effulgence would mark his path in the ecliptic, while through all surrounding space, at a trifling distance, would reign the lackness of

[Aug.

universal midnight. Doleful shades would, to the appearance of every spectator dwelling upon the earth, environ the greater part of mankind, engendering gloomy horror on each side of us, which, to each individual, as it affected all around him, would sit enthroned in grim desolation over the habitations of men.

In the language of a somewhat fanciful writer, "the sun would appear like a fire in the night, glaring and fierce, strongly contrasted upon a back ground of intense black, overpowering indeed the stars close to him, and those only; no others would hide their diminish'd heads,' but ever accompany him in bis daily course; such would be the appearance of the heavens! On earth we should be constantly overwhelmed with that diminutive portion of the earth immediately adjacent to us, while on either hand reigned obscurity and night. The infinite variety of compounded tints would immediately vanish, and in its stead be substituted light insupportably brilliant, contrasted with darkness, the shadow of death."

The crepuscule which, in many of the latitudes of our earth, particularly in the temperate zones, stands connected, not only with our comfort, but in a variety of ways with the expansion of our faculties, has been long ascertained to be wholly dependant upon the atmosphere. Did we exist in vacuo, nothing of the kind could, upon any principle of physiology, recreate our senses. The moment the sun descended beneath the plane of our horizon, would prove the commencement of a period of deepest shades, almost immediate darkness would wrap her gloomy mantle over terrestrial objects,-a contrast which, besides the injury accruing to our optics, as at present constituted, would, in many moral points of view, deprive us of incalculable advantages. If immediate and total darkness, in the midst of summer, spread her veil around us, as the sun left our hemisphere, except when irradiated from the borrowed splendour of the moon, or the faint twinkling of the stellar fires, the interesting spectacle, which, at certain periods of the year in the temperate regions of our globe, offers to the mind of man so fine a medium for the exercise of his powers,

See Keith, and other astronomical authorities. would

would be at once withdrawn. The invigorating and balmy coolness which refreshes the student in his walk, after the resplendent orb of day has withdrawn his beams, together with the delightful contemplations which it is wont to open in the soul attuned to beauty, would be extinct in the catalogue of human enjoyments, and the soft whisperings of poetic imagery would often lose their most kindred and delightful season of inspiration.

The glories which often accompany a setting sun, or his declination in the heavens, likewise could clearly never re-create the sense, were atmosphere denied to us. The glowing beauties and rich fantastic shading of an evening sky, the light fast dwindling in the western horizon, the dusky hue of night gathering thick in the azure fields of ether, which, to the gaze of mortals, bounds the vault of heaven, and gradually shrouds the face of Nature from the view, would at once vanish from human optics.

Some considerable time after the disc of the sun has receded from the gaze of those who inhabit the level of plains, we see its departing rays still lingering on the tops of the distant mountains; these rays, it is known, are not all reflected immediately from the orb, of whose splendour they afford a last remembrance, but reach these eminences through an angle of inflection.

By impinging against the upper regions of our atmosphere, where the aerial fluid is far more rare and subtle, those particles of light, which would otherwise have glided into the empty spaces of our system, are arrested in their course, and converge to the projecting excrescences of our globe, from whence they are again transmitted to

us.

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ripens, through all its stages of light, until the broad red disc of this luminary gleams upon our world in all the majesty of surpassing splendour.

Atmosphere is ordained to fulfil other purposes connected with physiology,-blessings incalculable, and not so immediately obvious to the generality of observers, much less to the "mute unconscious gaze" of vulgar mankind, follow in the train of this admirable provision in the economy of Nature. Subservient to high moral ends, in the varied order of life and happiness, the sublime phenomena in Meteorology prove that, without the medium which is, hence, presented for those vapours which float aloft, destined to irrigate the surface of our globe, wisdom ineffable could scarcely have contrived a more perfect system for supplying our physical exigencies. Yours, &c.

Mr. URBAN,

E. P.

June 1.

HE importance of Chronology is

denied; I will not, therefore, add a single word in its favour; but I must express my regret at the confusion which prevails in this department of literature. Many of the most distinguished talents have preceded me in this line; every one has a system peculiar to himself, and to this he endeavours to adapt the texts of ancient historians. An early partiality to History, and the acquirement of useful knowledge, have caused my application to the subject.

Amongst the numerous systems which have been offered to the world in different ages, that of the illustrious Newton has the most claim to our regard. He has thrown great light on the subject, and has corrected many absurdities in the common chronology; but, although he has been now dead 100 years, he is still, undeservedly, neglected by modern writers. Mr. Mitford is, I think, the only historian who has adopted it; if we except Mr. Gibbon, who has an essay on it, in which he adopts part, and rejects some. I wish to call the attention of the learned to the consideration of this system. When I said that Newton has corrected several absurdities in ancient history, I alluded to the extraordinary duration of the reigns of the monarchs they mention.

For