Chapter II: Part 2

Those elements which represent the moon's distance and motion are accurately known, and may be taken from the Nautical Almanac, being all embodied in the moon's parallax or semi-diameter, and in the declination and right ascension; but for the most important element,--the moon's mass, we in vain look to astronomy. In fact, it may be averred that the importance attached to astronomical authority, concerning the mass of the moon, has caused more trouble than any other question of the whole theory, until we trusted implicitly to the theory itself to determine it. The determination of three unknown elements, viz.: the moon's mass, the inclination of the axis of the vortex, and the right ascension of that axis, is a more difficult problem than at first sight appears, owing to the nature of the phenomena, which affords the only clue for its solution. There are six principal vortices ever in operation on the surface of the earth, and their disturbing influence extends from 200 to 400 miles. To find the precise centre, by one observer confined to one place, is difficult; and to separate them, so as to be fully assured that you have the right one, is perhaps still more so. Happily this tedious labor is accomplished, and we are able with confidence to give the following important elements, as very close approximations to the truth:

Mass of the moon 1/72.3
Obliquity of the axis of the vortex 15d to 32d variable.
Right ascension of ditto 250d to 290d variable.

It must be borne in mind that we are now discussing the main or central vortex of the earth; but before applying them to the calculation, we will explain the _modus operandi_, waiving for the present the consideration of the law of density in the Terral vortex. It is evident at first sight that if the periodic times of the parts of the vortex contiguous to the moon, are equal to the moon's period approximately, that the velocity of the ether is greater at the surface of the earth than the velocity of that surface. Now, we have before argued that the ether possesses inertia, it therefore would under such circumstances exert some mechanical action. Consequently, the aerial envelope of our globe, or its superior stratum, is impelled eastward by _convection_[4] of the more rapidly rotating ether. And from the extreme tenuity of its upper layers, is probably forced into immense waves, which will observe to a certain degree, a general parallelism north and south.

ATMOSPHERIC CURRENTS.

It is a well-known fact, that the prevailing current of the atmosphere in high latitudes is from the westward. The cause of this is ascribed by Professor Dove to the transfer of the equatorial portions to a higher latitude, by which the excess of its rotative velocity is made apparent, by outstripping the slower moving surface in its progress eastward. No doubt some effect is due to this, but still a difficulty remains. Let us follow this current. The polar current reaches the surface on the borders of the trades with less rotative velocity than the surface, and is, therefore, met by the surface as a current partaking of both motions. In the northern hemisphere it is north-east deflected to east as it approaches the southern trades. By the same reasoning, coming from the north before it readies the surface, it ought to be also a north-east wind above the lower westerly currents. Now it is an observed fact, that while in the latitude of New York, for instance, the lower westerly winds are to the easterly, as 3 or 4 to 1, in the highest regions of observed clouds, the ratio is much increased; and according to our own observations in this place,[5] we have never seen the highest cirrus clouds moving westward. How then is this continual interchange kept up? Assuredly we cannot have a current from the poles without a contrary current to the poles. If we go into the arctic circle, we again find the westerly and northerly winds predominating. If the current from the equator follows the surface, the westerly winds ought to be south-west. If it be above the surface wind, then the surface wind is the polar current, and ought to be north-east. Whereas, from the testimony of all who have visited these regions, the prevailing winds are north-west. How can this be?

Again, it is proved that the upper current near the equator is also from the westward--as near due west as possible. Take the latitude of St Vincent. The difference between the cosine of 13d and radius applied to the circumference, is about 600 miles, which would give 25 miles per hour to the eastward, in lat. 13d. But to do this, it is necessary to transfer it suddenly from the equator; for by a slow motion the easterly tendency would be lost. Give it 24 hours from the equator to lat. 13d, without any loss of easterly tendency, and it comes to that latitude with a velocity of 38 miles per hour to the northward, and only 25 to the eastward; we have, therefore, a wind from south-west by south. Yet it is known that in the tropics the highest visible clouds move from the westward. But as no such case could occur as a transfer in twenty-four hours without loss, and if we diminish the time, the wind is still more southerly. Meteorologists usually cite the falling of ashes at Jamaica during the eruption of Coseguina, in Guatamala, in February 1835, as coming from south-west, whereas the true direction was about west south-west, and the trade wind below was about north. But do we deny that there is an interchange between the frigid and torrid zones? By no means; but we would show that the great controlling power is external to our atmosphere, and that the relative velocities of the earth and the atmosphere is not alone adequate to account for it. By this view the polar current is a north-west wind (which is impossible by Professor Dove's theory), or is carried eastward by electric convection.

HUTTON'S THEORY.

Whether we adopt the views of Fourier or Poullet, as to the temperature of the planetary spaces, it is certain that it is at least equal to, or less than, the lowest temperature of our globe. It is also a well-known fact, that the capacity of air to hold vapor in solution, increases in a higher ratio than the temperature, so that the intermingling of saturated portions of air, at different temperatures, must _necessarily_ be attended by precipitation of moisture. This idea was advanced by Doctor Hutton, and considered competent to account for the prominent meteorological phenomena, until Professor Espy broached a questionable principle, (and which is rendered still more so by the late investigations of Regnault,) in opposition to Hutton's theory. That the theory is deficient, no one can gainsay. That Espy has rendered the question clearer, is equally hazardous to assert. Hutton failed in showing a cause for such intermingling on a sufficient scale; while Espy, it may be suspected, has misinterpreted facts, and incautiously rejected the only element possessing the power of raising the storm.

GREAT SPECIFIC HEAT OF THE ETHER.

Whatever may be the degree of condensation or rarefaction in the terral vortex, there must necessarily be a current down the pole or axis, thence to be deflected along the equatorial plane of the vortex, and this drain will be as perpetual as the rarefaction of the centre, (caused by the centrifugal force of rotation,) which calls it forth. It will now be perceived that the fluid of the vortex, which we shall still term ether, is neither more nor less than the electric fluid,--the mighty energising principle of space,--the source of motion,--the cause of magnetism, galvanism, light, heat, gravity, of the aurora, the lightning, the zodiacal light, of the tails and nebulosities of comets, of the great currents of our atmosphere, of the samiel, the hurricane, and the earthquake. It will be perceived that we treat it as any other fluid, in relation to its law of motion and condensation. But we have no right to base our calculations on its resistance, by the analogies presented by ponderable or atomic matter. Atomic fluids,--even pure air, may be considered viscid and tenacious when compared to an infinitely divisible fluid, between whose particles (if we may use the term) no _attraction_ of any kind exists. No ponderable matter can come in close contact without feeling the influence of the gravitating force which, at insensible distances,--such as the breadth of a wave of ether, is increased in power, and becomes a cohering and combining force. We contend that this fluid is the only fluid of space; when condensed it is positive, and seeks to escape; when rarefied it is negative, and receives from the contiguous space a restoration of its power. That it can give and receive, from planetary matter, what we call motion; and consequently can affect the temperature of such matter, and be in turn affected by it. And finally that, for its degree of inertia, it exceeds in elasticity and specific heat all other matter.

PROCESS OF DERANGEMENT.

This premised, we see that as the axis of the vortex traverses the surface of the earth, there is a tendency to derange the electric state of the parts travelled over, by bringing the atmosphere and surface of the earth under the rarefied centre of the vortex. For it is not the ether of the atmosphere alone that is affected. It is called forth from the earth itself, and partakes of the temperature of the crust,--carrying up into the upper regions the vapor-loaded atmosphere of the surface. The weather now feels close and warm; even in winter there is a balmy change in the feelings. The atmosphere then fills with haze, even to the highest regions of the clouds; the clouds themselves are ill defined; generally the wind comes in at E. S-E., or S., getting very fresh by the time it chops round to W. In from six to twelve hours from the time of the meridian passage, in this latitude, the Big Cumuli have formed, and commenced their march eastward. In summer time there is always thunder and lightning, when the passage is attended or followed by a storm. In winter, generally, but not always. In summer, the diameter of the storm is contracted; in winter, dilated; in consequence of this, summer is the best season to trace the vortices of the earth through their revolutions. Let us now attend a little to the results. The ether of the surface atmosphere partakes of the temperature of that atmosphere, so also the ether of the earth's crust partakes of the temperature of the crust; and its escape is rapid, compared with the ascent of the air. When it arrives at the colder layers of air above, its temperature sinks, and, on account of the greater specific caloric, it imparts a much higher temperature to those layers than is due to their position; an elevation consequently takes place,--begetting a drain from below, until the upper regions are loaded with a warm and vapory atmosphere. If the action of the sun conspires at the same time to increase the effect, the storm will be more violent. In twelve hours after the meridian passage of the vortex, the storm is brought under the parts of the ethereal atmosphere of the earth most remote from the axis; a reaction now takes place; the cold ether of space rushes in, and, on account of its great specific caloric, it abstracts from the warm atmosphere more than pertains to the difference of temperature, and there is a great condensation. Rain and hail may form in fearful quantities; and when the equilibrium is restored, the temperature will have fallen many degrees.

As it is important that we should have a clear view of the character of the ether, we will revert to the principle we have advocated, viz.: that in equal spaces there are equal momenta. What the ether wants in inertia, is made up by its motion or specific heat, considering in this case inertia to stand for weight when compared with ponderable matter; so that to raise an equivalent amount of inertia of ether to the same temperature as atmospheric air, will require as much more motion or specific heat as its matter is less. And this we conceive to be a law of space in relation to all free or gaseous matter. To apply it to solids would require a knowledge of the amount of force constituting the cohesion of the solid.

INFLUENCE OF DIMINISHED PRESSURE.

But there is another principle which modifies these effects. We have already adverted to the action of the tangential current of the vortex forcing the outer layers of the atmosphere into waves. These waves will be interfered with by the different vortices, sometimes being increased and sometimes diminished by them.[6] If these waves are supposed very wide, (which would be the case in the attenuated outside layers of the atmosphere,) the action of the vortex will be greater in its passage over a place, which at the time corresponded to the depression point of the wave, that is, to the line of low barometer; because here there would be less resistance to overcome in the passage of the ether from the surface of the earth into space; so that we may conceive each vortex making a line of storms each day around the earth, separated by less disturbed intervals. After the formation of the storm, it of course has nothing to do with the vortex that produced it; it travels in the general direction of the local atmosphere of the place--in intratropical latitudes westward, in extratropical latitudes eastward. If, therefore, the disturbance forms at the place of observation, there will probably be no storm; but further eastward its action would be more apparent or violent. It is impossible, of course, to lay down any general description which shall meet every case. It is a knowledge that can only be acquired by observation, and then is not readily or easily communicated. There are many contingencies to be allowed for, and many modifying causes to keep sight of, to enter into which would only be tedious; we shall, therefore, confine ourselves to the prominent phenomena.

ACTION OF THE POLAR CURRENT.

We have seen how the passage of the axis of the vortex may derange the electric tension of the parts passed over; but there is another mode of action not yet adverted to.

When the moon is at her perigee, the axis of the vortex passes through the centre of gravity of the earth and moon at C, and cuts off the segment RR. At the apogee, on account of her greater distance, and of her consequent power to _push_ the earth out from the axis of the vortex XX, the segment R'R' is only cut off by the axis; and the angle which the axis makes with the surface will vary with the arcs AR and A'R'; for these arcs will measure the inclination from the nature of the circle. In passing from the perigee to the apogee the axis will pass over the latitudes intermediate between R and R' in both hemispheres, neither reaching to the equator E, nor to the pole P. Let us now suppose a meridian of the earth, represented by the line NRS, N being north, and S south, and the surface of the atmosphere by N'S'; XX still representing the axis of the vortex, ordinarily inclined 34d or 35d to the surface. Let us also conceive the rotation of the earth to cease, (the action of the vortex remaining the same,) thus leaving the axis over a particular longitude. If the ether possesses inertia, there will be an actual scooping out of the upper portions, driving them southward to a certain distance, where the atmosphere will be piled up above the ordinary level. There will, therefore, be a strong contrary current at the surface of the earth to restore the equilibrium, and if the action be violent, the surface wind will be increased; so that if it be considered tangential to the surface at S, its own momentum will tend to make it leave the surface and mount up to T; and in this way increase the action due to the ether. Now, although the axis is never stationary, but travels round the earth in less than twenty-five hours, yet there is a tendency to this mode of action; and it is even sometimes palpable to the observer when the axis has passed immediately to the northward; for the pinnate shafts and branching plumes of the cirri often reach far to the south of the southern boundary of the storm. These shafts are always longer when radiating from the northward than when proceeding from the southward. The cause is understood by the above figure. At such a time, after dark, the auroral shafts will also be seen over the storm to the northward, but will be invisible to those beneath. There is this to be observed, however, that the visibility of the ethereal current (or the aurora) is more frequent when the passage of the vortex is not attended with any great commotion, its free passage being perhaps obstructed by too dry an atmosphere; hence it becomes more visible. But it may be asserted that a great aurora is never seen except when a vortex is near, and to the northward, and within a few hours of its passage over the meridian. We have, however, seen partial auroras to the south when none existed north, and also cases when the radiation was from west, but they are never as bright as in the north. They are all due, however, to the same cause; and we have frequently followed a vortex for three days to the northward, (that is, seen the effects of its meridian passage,) at 700 miles distance, by the aurora, and even by the lightning, which proves plainly that the _exterior layers_ of our atmosphere can reflect a flash of lightning, assisted by the horizontal refraction, otherwise the curvature of the earth would sink it ten miles below the horizon.

LIMITS OF THE VORTEX.

The action of the polar current of the ether, therefore, tends to cause a depression of the barometer, and an elevation to the _northward_ and southward, and there is a general set of the wind below to the point of greatest depression. The action of the tangential current works the outer surface of the atmosphere into great ridges and hollows, whose distances apart as well as actual dimensions, are continually changing under the influences of causes not yet alluded to, and it is in the hollows where the action of the polar current will be principally expended. Luckily for the earth, the axis of the vortex is never long in passing over any particular place. In this latitude, whose natural cosine is three-fourths, the velocity _westward_ is over 700 miles per hour; but at its extreme limits north, the motion is much slower, and is repeated for two or three days in nearly the same latitude, for then it begins to return to the south; thus oscillating in about one sidereal period of the moon. At its southern limit, the vortex varies but slowly in latitude for the same time, but the velocity is much greater. The extreme latitudes vary at different times with the eccentricity of the lunar orbit, with the place or longitude of the perigee, and with the longitude of the moon's ascending node, but in no case can the _central vortex_ reach within 5d of the equator, or higher than about 75d of latitude north or south. Hence there are no storms strictly speaking beyond 88d[7] of latitude; although a storm may be raging close by, at the turning point south, and draw in a very strong gale from the northward with a clear sky above. So also, although rains and short squalls may be frequent in the vapor-loaded atmosphere of the equator, yet the hurricane does not reach there, owing to the adjustment of the mass and distance of the moon, and the inclination of the axes of the vortices to the axis of the earth. If the temperature of the upper limit or highest latitude of the vortex, was equal to the temperature which obtains at its lowest limit, and the daily extremes of the solar influence as great, the hurricanes would be as violent at the one as the other, and even more so on account of the smaller velocity. But the deficiency of temperature and moisture, (which last is all-important,) prevents the full development of the effect. And even in the tropics, the progress of the sun, by its power in directing the great annual currents of the atmosphere, only conspires in the summer and autumn months, to bring an atmosphere in the track of the vortices, possessing the full degree of moisture and deficiency of electric tension, to produce the derangement necessary to call forth the hurricane in its greatest activity.

ROUTINE OF A STORM.

The novelty and originality of this theory will perhaps justify us in dwelling a little longer on what observation has detected. The vortex (and we are now speaking only of the central vortex) does not derange every place alike, but _skips_ over large tracts of longitude in its progress westward. We speak here of the immovable axis of the vortex as in motion; in reality it is the rotation of the earth which brings every meridian under its influence in some latitude once every twenty-four hours. The centre of greatest derangement forms the nucleus, towards which the surface currents, under certain restrictions, flow. The strongest current will, however, usually be from the south, on account of the inclination of the axis of the vortex to the surface of the earth.[8] These currents continuing onwards by their vires inertiae, according to the first law of motion, assist somewhat in conveying the warm surface wind, loaded with moisture, into the region of cloud; and the diminution of temperature causes the condensation of large masses of vapor, according to Hutton's views; and the partial vacuum thus produced, causes a still greater intermingling. But we have already shown that this is not the sole cause, nor is it ever more than partially accomplished. The ether of the lower atmosphere, and of the crust of the earth, is disturbed, and rushes towards the rarefied axis from the surface, and with the temperature of the surface, thus conveying the surface atmosphere, in a measure, along with it. In the upper regions, this ether (or electric fluid) cools down, or parts with some of its heat, to the air of those regions, and, by its great specific caloric, necessarily and unduly increases the temperature of the air. This, by its expansion and ascension will cause a further influx from below, until the upper atmosphere becomes loaded with vapor. In twelve hours, at least, a reaction must take place, as that part of the earth's surface is carried six or seven thousand miles from the axis, where the ether is more dense. This in turn descends to the surface, carrying with it the temperature of space, at least 60d below zero; a great condensation must follow; local derangements of the electric equilibrium in the centre of large clouds, when the condensation is active, must now take place, while partially nonconducting masses intervene, to prevent an instantaneous restoration of the equilibrium, until the derangement is sufficient to cause the necessary tension, when all obstacles are rent asunder, and the ether issues forth, clothed in the power and sublimity of the lightning. It is a fearfully-energetic fluid, and, when sufficiently disturbed, competent to produce the most violent tornado, or the most destructive earthquake. That these two phenomena have simultaneously occurred, seems well authenticated; but the earthquake, of course, must be referred generally to derangements of the electric equilibrium of the earth's interior, of which at present we know but little.

The day or morning previous to the passage of the vortex, is frequently very fine, calm, mild, and sleepy weather,--commonly called a weather breeder. After the storm has fully matured, there is an approach of the clouds to the surface, a reduction of the temperature above, and the human body feels the change far more than is due to the fall of temperature. This is owing to the cold ether requiring so much heat to raise its temperature to that of surrounding bodies, or, in other words, is due to its great specific caloric. In summer, this falling of the upper layers in front of the storm is so apparent, that every part is seen to expand under the eye by perspective,--swelling, and curling, and writhing, like the surface of water or oil when just commenced boiling. The wind now partakes of the motion of the external ether, and moves with the storm eastward (in this latitude), or from N-E. to S-E., until the action ceases.

CONDITIONS NECESSARY TO PRODUCE A STORM.

The vortex, in its passage round the earth, may only meet with a few localities favorable for producing a very violent storm; but these nuclei will generally be connected by bands of cloudy atmosphere; so that could we view them from the moon, the earth would be belted like the planet Jupiter. There is reason to suspect, also, that there are variations in the energy of the ethereal motions, independent of the conditions of the earth and its atmosphere, which affects even the radial stream of the sun. For the zodiacal light, which is caused by this radial stream, is at times much more vivid than at others. Also in the case of the aurora, on our own globe. On this point there is much to say, but here is not the place. The conditions favorable for the production of a storm at the _central_ passage of a vortex, are a previous exemption from excitement _ceteris paribus_, a high temperature and dew point, a depression of the barometer, and local accumulation of electric tension, positive or negative; and these are influenced by the storms in other places controlling the aerial currents, and thus determining the atmosphere of the place.

LATERAL VORTICES.

We have already alluded to the lateral vortices of the terral system. We must now resort to a diagram.

In the following figure, the arrows represent the ethereal current of the terral vortex; the linear circle, the earth; C the centre of gravity of the earth and moon, and, consequently, the central vortex or axis of the vortex of the earth, I represents the position of the inner vortex, and O that of the outer vortex. These two last are eddies, caused by the obstacle presented by the earth in being _pushed_ out from the centre by the moon, and are called lateral vortices. There are, therefore, two lateral vortices, and one central, in both hemispheres, and by this simple arrangement is the earth watered, and the atmospheric circulation produced.

ILLUSTRATION OF THEIR ACTION.

If we place a globe in a vessel of water, so that the vertex shall only just be covered, and place the globe eccentrically in the vessel so that the centre of the vessel may not be too far from the outside of the globe, and then impart an equable but slow motion to the water, in the manner of a vortex; by viewing the reflected light of the sky from the surface of the water above the globe, we shall be able to trace a succession of dimples, originating at I and O, and passing off with the current, and dying away. The direction of the fluid in these little eddies, will be the same as the direction of the current in the main vortex. If we displace the globe, so as to remove it far from the centre of the vessel, and impart the same motion, the vortex I will be found at E, and the direction of the current will be contrary to the direction of the fluid in the vessel. In the case of the earth and moon, the displacement can never change the position of the inner vortex much. It will always be to the right hand of the central vortex in north latitudes, and in consequence of the ether striking our globe in such a position, the current that is deflected from its true path, by the protuberance of the earth forcing it inside, is prevented by the circular current of the parts nearer the axis of the vortex, from passing off; so that a vortex is formed, and is more violent, _ceteris paribus_, than the vortex at O.

ORDER OF OCCURRENCE.

Whether this mode of action has been correctly inferred, matters little; the lateral vortices follow the law of such a position. The inner vortex always precedes the central from five to eight days, when ascending in this latitude, and comes to the meridian after the moon. The outer vortex, on the contrary, follows the central in its monthly round, and comes to the meridian before the moon. It will be readily understood that if the axes of these lateral vortices be produced through the earth, they will pass through similar vortices in the opposite hemisphere; but as the greatest latitude of the one, corresponds to the least latitude of the other, the same calculation will not answer for both. The same remark applies to the central vortex also.

Thus there are six passages each month over latitude 41d; but as there are intervals of 3d to 6d between two consecutive passages of the same vortex, it may happen that an observer in the middle latitude, would perhaps see nothing of their effects without looking for them. Generally speaking, they are not only seen, but felt. The time of the passage of the outer vortex ascending, corresponds so nearly (in 38d of latitude) at certain times, with the passage of the central vortex descending, that the two may be considered one if attention is not directed to it. The orbits of these lateral vortices depend, like that of the central vortex, on the orbit of the moon for eccentricity, but the longitudes of the perigee will not correspond with the longitude of the moon's perigee. This follows from the theory. As the elements of these orbits are only approximately determined, we shall confine our calculations to the orbit of the central vortex.

REDFIELD'S THEORY OF STORMS.

It will now appear plainly to the reader, that this theory of storms differs in every particular from the rival theories of Redfield and Espy, both as to the cause and the _modus agendi_. It would appear at first sight, as if the discovery of these vortices would at once remedy the great defect in the theory of Redfield, viz.: that no adequate cause is assigned for the commencement and continuation of the vorticose motion, in the great circular whirlwinds which compose a storm. The facts, however, are adverse to such an application. According to Mr. Redfield, the rotation of a circular storm in the northern hemisphere is from right to left, and the reverse in the southern. The author's attention has, of course, been considerably directed to this point; but in every case he has been unfortunate in finding in the clouds a rotation from left to right. Some cases are mentioned in the appended record of the weather. He has also noticed many of those small whirlwinds on arid plains, in Egypt, in Mexico, and in California, which, in the great majority of cases, were also from left to right. His opportunities, however, have not extended to the southern hemisphere. This theory has not, however, been formed on theoretic views, but by looking nature in the face for years, and following her indications. Accordingly, we find that the changes of the wind in a storm forbid the adoption of the circular hypothesis.

WHIRLWINDS VERY LIMITED IN DIAMETER.

The theory, as extended by Col. Reid, rests on a simple rotation around a progressing centre, and is found sometimes supported by evidence of the most violent action at the centre, and sometimes by showing that the central portion is often in a state of calm. We do not attempt to reconcile these views; but would merely observe, that an atmospheric vortex must be subject to the same dynamical laws as all other vortices; and inasmuch as the medium cannot differ greatly in density, from the centre to the circumference, the periodic times of the parts of the vortex, must be directly as their distances from the axis, and consequently the absolute velocities must be equal. If Mr. Redfield resorts to a spirally inward current, it would be a centripetal instead of a centrifugal current, and therefore could not cause the barometer to fall, which was the best feature of the theory in its primitive form. The absolute velocity of the wind is the important element which most concerns us. In the case of a tornado of a few yards in diameter, there is no doubt a circular motion, caused by the meeting of opposing currents; but this may be considered a circle of a very small diameter. The cause is due to a rapid escape of electric or ethereal matter, from the crust of the earth, called forth by the progressing, disturbed space above; this involves the air, and an ascending column in rotation begets the rush on all sides to that column in straight lines: consequently, the velocities will be inversely as the distances from the axis, and the force of the current as the squares of the velocities. On the circular theory, no increase of velocity would be conferred by the approach of the centre, and consequently no increase of power.

OBJECTION TO CIRCULAR STORMS.

Another objection to the circular theory of storms, is the uniformity of phase. If that theory be true, we see no reason why a person should not be sometimes on the northern side of the gale. By referring to a diagram, we perceive that on the northern side the changes of the wind pursue a contrary direction to what they do on the south, yet in nine cases out of ten, each vessel meeting a hurricane will find the same changes of wind as are due to the southern side of the storm. It is true, that if a vessel be to the northward of a great hurricane, there will almost certainly be a north-east gale drawn in, and this might be set down as the outer limits of a circular storm. But when the storm really begins, the wind comes round south-east, south, south-west, ending at north-west, and frequently is succeeded, on the following day, (if in middle latitude,) by a moderate breeze from the northward. Now, if the north-east gale spoken of above, was the outer limits of an atmospheric vortex, a vessel sailing west ought not to meet the hurricane, as a north-east wind is indicative of being already on the west side, or behind the storm.

Again, the characters of the winds, and appearances at the different changes, are opposed to the circular theory. At a distance of fifty miles from the centre of a storm, the wind which passes over a ship as a southerly wind, will have made a rotation and a half, with the hurricane velocity, before the same wind can again pass the ship as a northerly wind, (supposing the progress eastward, and the ship lying to,) that is, the same wind which in another place was a south wind two hours before, and after only going one degree north, becomes a northerly wind,--changed in character and temperature, as every seaman is well aware. In a storm, if the circular theory be true, the character and temperature should be the same, no matter from what point the wind is blowing. This should be a conclusive argument.

Mr. Espy has also changed his ground on the storms of the United States; he does not now contend that the winds blow inwards to a centre, but to a line either directly or obliquely. Thus we see that while Mr. Redfield concedes to Mr. Espy a spirally inward current, the latter also gives up a direct current to the centre, to Mr. Redfield. This shows at least an approximation to the truth.

It is not necessary for the support of this theory, that we should derive any materials from the ruins of others; we shall therefore not avail ourselves of certain discrepant results, which can be found in many of the storms cited by Colonel Reid. With respect to Mr. Espy's _cause_ of storms, the experiments of Regnault may be considered as decisive of the question:--1st, because the specific heat of vapor is so much less than Espy assumed it to be; and 2d, because the expansion of air in a free space does not suffer any change of volume by ascending, except what is due to diminished pressure, and the natural temperature of that elevation.

INDICATIONS OF A STORM.

In accordance with our theory, the direction and force of the wind in a storm are due to ascending columns of air, supplied from the upper portion of the atmospheric stratum beneath the clouds. The commotion begins at the highest limits of the cirri, and even at greater elevations. Hence, the hazy appearance of the sky is a legitimate precursor of the coming gale. As a general thing, the wind will blow (at the surface) towards the centre of greatest commotion, but it is too dependent on the ever-varying position and power of temporary nuclei of disturbance, to be long steady, except when the disturbance is so remote that its different centres of induction are, as it were, merged into one common focus. When a vortex is descending, or passing from north to south, and withal very energetic at the time, the southerly wind (which may always be considered the principal wind of the storm in this hemisphere) may blow steadily towards the vortex for three or even four days. When a vortex is ascending, the induced northerly current will be comparatively moderate, and be frequently checked by the southerly wind overblowing the storm, and arriving the day before the vortex which produced it.

The important point for the navigator, is to know the time of meridian passage of the vortex, and its latitude at the time of the passage, and then be guided by the indications of the weather and the state of barometer. If it commences storming the day before the passage, he may expect it much worse soon after the passage; and again, if the weather looks bad when no vortex is near, he may have a steady gale setting towards a storm, but no storm until the arrival of a vortex. Again, if the barometer is low the day before the vortex passes, there may be high barometer to the west, and the passage be attended by no great commotion, as it requires time for the storm to mature, and consequently its greatest violence will be to the east. If at the ship the barometer is high, the vortex may still produce a storm on a line of low barometer to the west, and this line may reach the ship at the time of the passage. In tropical climates the trouble must be looked for to the eastward; as a storm, once excited, will travel westward with that stratum of atmosphere in which the great mass of vapor is lodged, and in which, of course, the greatest derangement of electric tension is produced.

It will now be seen that we do not admit, with Col. Reid, that a storm continues in existence for a week together. Suppose a hurricane to originate in the Antilles at the southern limits of a vortex, the hurricane would die away, according to our theory, if the vortex did not come round again and take up the same nucleus of disturbance. On the third day the vortex is found still further north, and the apparent path of the hurricane becomes more curved. In latitude 30d the vortex passes over 3d or 5d of latitude in a day; and here being the latitude where the lower atmospheric current changes its course, the storm passes due north, and afterwards north-east. Now, each day of the series there is a distinct hurricane, (caused by an increase of energy in a particular vortex, as we have before hinted,) each one overlapping on the remains of the preceding; but in each the same changes of the wind are gone through, and the same general features preserved, as if it were truly a progressive whirlwind, except that each vessel has the violent part of it, as if she was in the southern half of the whirl. The apparent regularity of the Atlantic storms in direction, as exhibited by Col. Reid, are owing in a great degree to the course of the Gulf Stream, in which a vortex, in its successive passages in different latitudes, finds more favorable conditions for the development of its power, than in other parts of the same ocean; thus showing the importance of regarding the established character of storms in each locality, as determined by observation. In this connection, also, we may remark, that the meridians of greatest magnetic intensity are, _ceteris paribus_, also the meridians of greatest atmospheric commotion. The discovery of this fact is due to Capt. Sabine. The cause is explained by the theory.

As it is the author's intention to embody the practical application of this theory to navigation, with the necessary rules and tables, in a separate work, sufficient has been said to familiarize the reader with the general idea of a cause external to the earth, as the active motor in all atmospheric phenomena. We will therefore only allude in a general way to the principal distinguishing feature of the theory. We say, then, that the wind in a storm is not in rotation, and it is a dangerous doctrine to teach the navigator. We also assert as distinctly, that the wind _in_ a storm does not blow from all sides towards the centre, which is just as dangerous to believe. If it were wise to pin our faith to any Procrustean formula, we might endorse the following propositions: That at the beginning of a storm the wind is from the equator towards the poles in every part of the storm; that, at a later date, another current (really a polar current deflected by convection) sets in at right angles to the first one; and that at the end of the storm there is only _one_ wind blowing at right angles to the direction at the beginning. Outside the storm, considered as a hundred, or two or three hundred miles in diameter, there is, under certain limitations, a surface wind setting towards the general focus of motion and condensation, and this surface wind will be strongest from the westward, on account of the motion of the whole atmosphere in which these other motions are performed being to the eastward.[9] The whole phenomenon is electrical or magnetic, or electro-magnetic or ethereal, whichever name pleases best. The vortex, by its action, causes a current of induction below, from the equator, as may be understood by inspecting Fig. 2, which in the northern hemisphere brings in a southerly current by convection: the regular circular current, however, finally penetrates below, as soon as the process of induction has ceased; and thus the polar current of the atmosphere at last overcomes the equatorial current in a furious squall, which ceases by degrees, and the equilibrium is restored.

Every locality will have its peculiar features; in each, the prevailing wind will be at right angles to the magnetic meridian, and the progress of the storm will tend to follow the magnetic parallel, which is one reason why the Atlantic and Indian Ocean storms have been mistaken for progressive whirlwinds. When these views are developed in full, the mariner can pretty certainly decide his position in the storm, the direction of its progress, and its probable duration.

FOOTNOTES:

[3] The specific heat of the ether being a constant factor, it may be divided out.

[4] A term adopted by Prof. Faraday to denote the mode in which bodies are carried along by an electrical current.

[5] Ottawa, Ill.

[6] The principal cause of these waves is, no doubt, due to the vortices, and the eastern progress of the waves due to the rotating ether; but, at present, it will not be necessary to separate these effects.

[7] The inner vortex may reach as high as 83d when the moon's orbit is favorably situated.

[8] The curvature of the earth is more than 10 miles in a distance of 300 miles.

[9] In middle latitudes.

SECTION SECOND.

MECHANICAL ACTION OF THE MOON.

We will now proceed to give the method of determining the latitude of the axis of the vortex, at the time of its passage over any given meridian, and at any given time. And afterwards we will give a brief abstract from the record of the weather, for one sidereal period of the moon, in order to compare the theory with observation.

In the above figure, the circle PER represents the earth, E the equator, PP' the poles, T the centre of the earth, C the mechanical centre of the terral vortex, M the moon, XX' the axis of the vortex, and A the point where the radius vector of the moon pierces the surface of the earth. If we consider the axis of the vortex to be the axis of equilibrium in the system, it is evident that TC will be to CM, as the mass of the moon to the mass of the earth. Now, if we take these masses respectively as 1 to 72.3, and the moon's mean distance at 238,650 miles, the mean value of TC is equal to this number, divided by the sum of these masses,--_i.e._ the mean radius vector of the little orbit, described by the earth's centre around the centre of gravity of the earth and moon, is equal 238650/(72.3+1) = 3,256 miles; and at any other distance of the moon, is equal to that distance, divided by the same sum. Therefore, by taking CT in the inverse ratio of the mean semi-diameter of the moon to the true semi-diameter, we shall have the value of CT at that time. But TA is to TC as radius to the cosine of the arc AR, and RR' are the points on the earth's surface pierced by the axis of the vortex, supposing this axis coincident with the pole of the lunar orbit. If this were so, the calculation would be very short and simple; and it will, perhaps, facilitate the investigation, by considering, for the present, that the two axes do coincide.

In order, also, to simplify the question, we will consider the earth a perfect sphere, having a diameter of 7,900 miles, equal to the actual polar diameter, and therefore TA is equal to 3,950 miles.

In the spherical triangle given on next page, we have given the point A, being the position of the moon in right ascension and declination in the heavens, and considered as terrestrial latitude and longitude.

Therefore, PA is equal to the complement of the moon's declination, P being the pole of the earth, and L being the pole of the lunar orbit; PL is equal to the obliquity of the lunar orbit, with respect to the earth, and is therefore given by finding the true inclination of the lunar orbit at the time, equal EL, (E being the pole of the ecliptic,) also the true longitude of the ascending node, and the obliquity of the ecliptic PE. Now, as we are supposing the axis of the vortex parallel to the pole of the lunar orbit, and to pierce the earth's surface at R, ARL will evidently all be in the same plane; and, as in the case of A and L, this plane passes through the earth's centre, ARL must all lie in the same great circle. Having, therefore, the right ascension of A, and the right ascension of L, we have the angle P. This gives us two sides, and the included angle, to find the side LA. But we have before found the arc AR; we therefore know LR. But in finding LA, we found both the angles L and A, and therefore can find PR, which is equal to the complement of the latitude sought.

We have thus indicated briefly the simple process by which we could find the latitude of the axis of the central vortex, supposing it to be always coincident with the pole of the lunar orbit. The true problem is more complicated, and the principal modifications, indicated by the theory, are abundantly confirmed by observation. The determination of the inclination of the axis of the vortex, its position in space at a given time, and the law of its motion, was a work of cheerless labor for a long time. He that has been tantalized by hope for years, and ever on the eve of realization, has found the vision vanish, can understand the feeling which proceeds from frequent disappointment in not finding that, whose existence is almost demonstrated; and more especially when the approximation differs but slightly from the actual phenomena.

The chief difficulty at the outset of these investigations, arose from the conflicting authority of astronomers in relation to the mass of the moon. We are too apt to confound the precision of the laws of nature, with the perfection of human theories. Man observes the phenomena of the heavens, and derives his means of predicting what will be, from what has been. Hence the motions of the heavenly bodies are known to within a trifling amount of the truth; but it does not follow that the true explanation is always given by theory. If this were so, the mass of the moon (for instance) ought to be the same, whether deduced from the principle of gravitation or from some other source. This is not so. Newton found it 1/40 of that of the earth. La Place, from a profound theoretical discussion of the tides, gave it as 1/58.6, while from other sources he found a necessity of diminishing it still more, to 1/68, and finally as low as 1/75. Bailly, Herschel, and others, from the nutation of the earth's axis, only found 1/80, and the Baron Lindenau deduced the mass from the same phenomenon 1/88. In a very recent work by Mr. Hind, he uses this last value in certain computations, and remarks, that we shall not be very far wrong in considering it as 1/80 of the mass of the earth. This shows the uncertainty of the matter in 1852. If astronomy is so perfect as to determine the parallax of a fixed star, which is almost always less than one second, why is it that the mass of the moon is not more nearly approximated? Every two weeks the sun's longitude is affected by the position of the moon, alternately increasing and diminishing it, by a quantity depending solely upon the relative mass of the earth and moon, and is a gross quantity compared to the parallax of a star. So, also, the horizontal parallax--the most palpable of all methods--taken by different observers at Berlin, and the Cape of Good Hope, (a very respectable base line, one would suppose,) makes the mass of the moon greater than its value derived from nutation; the first giving about 1/70, the last about 1/74.2. Does not this declare that it is unsafe to depend too absolutely on the strict wording of the Newtonian law of gravitation. Happily our theory furnishes us with the correct value of the moon's mass, written legibly on the surface of the earth; and it comes out nearly what these two phenomena always gave it, viz.: 1/72.3 of that of the earth. In another place we shall inquire into the cause of the discrepancy as given by the nutation of the earth.

MOTION OF THE AXIS OF THE VORTEX.

If the axis of the terral vortex does not coincide with the axis of the lunar orbit, we must derive this position from observation, which can only be done by long and careful attention. This difficulty is increased by the uncertainty about the mass of the moon, already alluded to, and by the fact that there are three vortices in each hemisphere which pass over _twice_ in each month, and it is not _always_ possible to decide by observation, whether a vortex is ascending or descending, or even to discriminate between them, so as to be assured that this is the central descending, and that the outer vortex ascending. A better acquaintance, however, with the phenomenon, at last dissipates this uncertainty, and the vortices are then found to pursue their course with that regularity which varies only according to law. The position of the vortex (the central vortex is the one under consideration) then depends on the inclination of its axis to the axis of the earth, and the right ascension of that axis at the given time. For we shall see that an assumed immobility of the axis of the vortex, would be in direct collision with the principles of the theory.