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But how is this law to be arrived at? The action of the common whirlwind from multiplied observation may settle whether the latter be invariable or not; but the cause of the whirling motion imparted to the air can probably never be more than surmised even by those deeply versed in aërology and statics. How far the aqueous vortex, which is said to revolve always from right to left, (we have tried an experiment and found it so,) may be considered analogous to the aërial one, we shall not offer an opinion; but we had an opportunty a few months ago (26th of February, last year,) of observing a whirlwind upon a small scale, which we shall describe.

It formed a complete circle, as correctly so to appearance, as if the outline of the periphery had been struck by a pair of compasses. The gyration, from the moment the wind first impinged against the ground to its dispersion was, from right to left, which was distinctly traceable from the dust in its evolution giving the meteor a visible form; it was cone shaped, the dust ascending spirally to a point, where it was thrown off into the air. It was about 6 feet in diameter, and lasted 30 seconds, pursuing a devious course to the N.N.E., the wind at the time being at N.b.W.

Any thing obstructing the free action of a current of air, every body knows will turn it aside, and give it a curved course; and we may not unreasonably believe that two veins of wind blowing in particular directions inay combine and produce a rotary motion. It is not easy to decide, whether either of these operations alone would afford a solution that might be considered unobjectionable. In the first instance, an obstruction to the direct descent (we consider the hurricane a descending whirlwind, not an ascending one,) of the gravitating aèrial current can probably, only arise from its coming in contact with a stratum of air of different density, and this at some elevation, for, as the lower atmosphere into which it descends cannot be at a lower temperature, any difference in that particular would act directly contrary, and assist instead of retarding or opposing the action of gravity, an effect of the grand mysterious principle which retains all nature in one harmonious bond.

That the progressive motion of a hurricane is independent of the circumvolving current of air, seems to admit of doubt, as it is reasonable to conceive it to be a consequence of the rotary motion; and if so, in some measure connected with the wind. That the impetus imparted to the meteor may be occasioned by the powerful action of violent wind sweeping round a centre, appears to be a rational conclusion, but that the direction of the course should generally be to the N. W., is, a curious circumstance still left for investigation.

If we were merely to judge from the direction of the rotation, should we not be apt to consider, that from the propulsive motion, if that guided it, the course of the storm would be to the west, or even southerly of that point?

We may remark that, although the N.W. direction has been traced, in the majority of cases investigated by Mr Redfield, yet no one knows the actual place of origin of any individual storm, or what direction it

No. 1.-VOL. XVII.

may take, when it received its first impulse. If, however, we should be warranted in drawing a conclusion from the first known direction, taken by the typhoon, which is a similar phenomenon, we would say that, the first course of the hurricane is to the S.W.; and this would lead us to the variable latitudes as the place of origin of, at least many of, these progressive tempests.

The perennial wind does not appear to have any influence on the course pursued by the hurricane, as taking W.S.W. as the general direction of the former, it would strike the meteor obliquely on the posterior verge, and did it affect the latter, we should expect to find it following a pretty uniform path between S.W. and W. May we, therefore, not consider that the course of the hurricane is governed by some principle more powerful than the trade-wind, or the rotation of the wind of the storm itself?

We may be allowed to dissent, without it being expected that we should offer a cause, from the opinion that the orbital, or diurnal motions of the earth have any influence in this, or indeed in any case, except those of the succession of night and day, and the seasons. The tremendous velocity, astounding even in contemplation, of the one, and the extreme regularity of the other, leaving every other consideration aside, would seem sufficient to negative such an opinion, yet we have seen it stated that the flight of birds is effected by the rotation of the earth.

The sweep of the hurricane to the northward is curious, as it recedes from a rarefied air to one considerably denser, the course sometimes, being ultimately reversed from that pursued near the islands. There can be no effect without a cause; hence the question.—What power imparts this peculiar curve, so generally pursued, to these meteors? It is probable, that, those storms which touch the Florida stream, may be afterwards guided by it; yet it is true, that some have followed the same curvilinear course, to the eastward of that stream; and undoubtedly the set or flow of the waters in an earlier stage of their progress, would not incline them to the N.W., but to the west or southward of that point.

As a portion of the route of these storms lies along the continental line, we might at first consider, that, but for the intervention of the land, they would pursue a direct course across the Pacific, and so on towards the Indian Ocean; but, it appears that, although many hurricanes follow the line of the American continent, some have reached the land, and swept away, no one knows where.

The remark of Colonel Capper, that hurricanes were unknown in the great ocean, has been disapproved by Capt. Kotzebue, who ascertained that, at Radack Island, in 10° N., and 190° W., hurricanes from S.W., of great violence, sometimes occur in September and October; and the natives always anticipate with dread, the recurrence of those months.

These tempests are probably similar to those of the West Indies, and the remark of the natives, that the wind comes from the S.W., may be considered as referring merely to the crisis, or nearest approach of the centre of the storm to the island; at which time, the wind would be at its utmost violence. It is remarkable, however, that in the Atlantic, the parallel named is rarely visited by a tempest of that character.

It is singular, that Dr. Franklin, when treating of whirlwinds, should not have struck upon the idea, that the current of air moved round a centre, but should have considered those meteors as proceeding from concentric currents; “a fluid moving from all points horizontally towards a ccntre.”

Upon the strength of this hypotheses, it seems at first equally singular, that Colonel Capper should have offered an opinion which we now kuow to be substantially correct, with respect to the hurricane, according to Mr. Redfield's theory, of which he knew nothing. But our surprise will cease in the latter case, when we come to examine both, and find that similar results will follow in either, whether the wind shall blow towards, or round a centre. The Colonel says : “ It would not, perhaps, be a matter of great difficulty, to ascertain the situation of a ship in a whirlwind, by observing the strength and changes of the wind : if the changes are sudden, and the wind violent, in all probability the ship must be near the centre or vortex of the whirlwind; whereas, if the wind blows a great length of time from the same puint, and the changes are gradual, it may be reasonably supposed the ship is near the extremity of it."

Another point for consideration is, the variable rate of the progressive velocity. The only regular feature of the giant meteor, as far as our present knowledge goes, is the gyration, which, indeed, to the seaman, is the main point, as it robs the storm of some of its terrors.

But whether we are to look for the cause of the irregularity of its rate, to what is going on above, or to the condition of the medium through which it sweeps, remains for elucidation. If there should be intervals when the current of air becomes less energetic, would these be sufficient to account for the retardation, and renewed energy, for the accelleration? The pivot upon which this question rests, seems to be, whether the progression be dependant upon the force of the circumvolving wind. We have elsewhere ventured an opinion, which, although, it may not be considered conclusive, at least appears reasonable, that both these conditions principally depend upon the amount of disarrangement in the lower atmosphere over the islands, and through which the storm moves; but we candidly acknowledge our inability to account for the discrepancy of the meteor turning away from the rarefied air, and advancing in a direction towards the north; our aim is, however, rather to seek the truth, than to insist upon our own hypotheses, however plausible they may appear to oneself, not being imbued with the pertipacity of Goldsmith's Parson.

As hurricanes do not pursue a uniform velocity, the rate of their actual progression can only be a mean of the whole between two given points, and this can only be arrived at after they have ceased to act on any two or more stationary spots, or on two vessels, when the exact time of commencement and conclusion have been respectively noted, with the distance that separated the vessels.

may take, when it received its first impulse. If, however, we should be warranted in drawing a conclusion from the first known direction, taken by the typhoon, which is a similar phenomenon, we would say that, the first course of the hurricane is to the S.W.; and this would lead us to the variable latitudes as the place of origin of, at least many of, these progressive tempests.

The perennial wind does not appear to have any influence on the course pursued by the hurricane, as taking W.S.W. as the general direction of the former, it would strike the meteor obliquely on the posterior verge, and did it affect the latter, we should expect to find it following a pretty uniform path between S.W. and W. May we, therefore, not consider that the course of the hurricane is governed by some principle more powerful than the trade-wind, or the rotation of the wind of the storm itself?

We may be allowed to dissent, without it being expected that we should offer a cause, from the opinion that the orbital, or diurnal motions of the earth have any influence in this, or indeed in any case, except those of the succession of night and day, and the seasons. The tremendous velocity, astounding even in contemplation, of the one, and the extreme regularity of the other, leaving every other consideration aside, would seem sufficient to negative such an opinion, yet we have seen it stated that the flight of birds is effected by the rotation of the earth.

The sweep of the hurricane to the northward is curious, as it recedes from a rarefied air to one considerably denser, the course sometimes, being ultimately reversed from that pursued near the islands. There can be no effect without a cause; hence the question.- What power imparts this peculiar curve, so generally pursued, to these meteors? It is probable, that, those storms which touch the Florida stream, may be afterwards guided by it; yet it is true, that some have followed the same curvilinear course, to the eastward of that stream; and undoubtedly the set or flow of the waters in an earlier stage of their progress, would not incline them to the N.W., but to the west or southward of that point.

As a portion of the route of these storms lies along the continental line, we might at first consider, that, but for the intervention of the land, they would pursue a direct course across the Pacific, and so on towards the Indian Ocean; but, it appears that, although many hurricanes follow the line of the American continent, some have reached the land, and swept away, no one knows where.

The remark of Colonel Capper, that hurricanes were unknown in the great ocean, has been disapproved by Capt. Kotzebue, who ascertained that, at Radack Island, in 10° N., and 190° W., hurricanes from S.W., of great violence, sometimes occur in September and October; and the natives always anticipate with dread, the recurrence of those months.

These tempests are probably similar to those of the West Indies, and the remark of the natives, that the wind comes from the S.W., may be considered as referring merely to the crisis, or nearest approach of the centre of the storm to the island; at which time, the wind would be

at its utmost violence. It is remarkable, however, that in the Atlantic, the parallel named is rarely visited by a tempest of that character.

It is singular, that Dr. Franklin, when treating of whirlwinds, should not have struck upon the idea, that the current of air moved round a centre, but should have considered those meteors as proceeding from concentric currents; "a fluid moving from all points horizontally towards a ccntre."

Upon the strength of this hypotheses, it seems at first equally singular, that Colonel Capper should have offered an opinion which we now kuow to be substantially correct, with respect to the hurricane, according to Mr. Redfield's theory, of which he knew nothing. But our surprise will cease in the latter case, when we come to examine both, and find that similar results will follow in either, whether the wind shall blow towards, or round a centre. The Colonel says : “ It would not, perhaps, be a matter of great difficulty, to ascertain the situation of a ship in a whirlwind, by observing the strength and changes of the wind : if the changes are sudden, and the wind violent, in all probability the ship must be near the centre or vortex of the whirlwind; whereas, if the wind blows a great length of time from the same pint, and the changes are gradual, it may be reasonably supposed the ship is near the extremity of it."

Another point for consideration is, the variable rate of the progressive velocity. The only regular feature of the giant meteor, as far as our present knowledge goes, is the gyration, which, indeed, to the seaman, is the main point, as it robs the storm of some of its terrors.

But whether we are to look for the cause of the irregularity of its rate, to what is going on above, or to the condition of the medium through which it sweeps, remains for elucidation. If there should be intervals when the current of air becomes less energetic, would these be sufficient to account for the retardation, and renewed energy, for the accelleration? The pivot upon which this question rests, seems to be, whether the progression be dependant upon the force of the circumvolving wind. We have elsewhere ventured an opinion, which, although, it may not be considered conclusive, at least appears reasonable, that both these conditions principally depend upon the amount of disarrangement in the lower atmosphere over the islands, and through which the storm moves; but we candidly acknowledge our inability to account for the discrepancy of the meteor turning away from the rarefied air, and advancing in a direction towards the north; our aim is, however, rather to seek the truth, than to insist upon our own hypotheses, however plausible they may appear to oneself, not being imbued with the pertiDacity of Goldsmith's Parson.

Aš hurricanes do not pursue a uniform velocity, the rate of their actual progression can only be a mean of the whole between two given points, and this can only be arrived at after they have ceased to act on any two or more stationary spots, or on two vessels, when the exact time of commencement and conclusion have been respectively noted, with the distance that separated the vessels.

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