Part 8 (1/2)
[19] It is worthy of notice here, that New York, which only differs by about 40 miles of lat.i.tude and 800 in longitude, had the storm earlier, near the time of the pa.s.sage, as appears by the appended account of it.
This proves, that a storm affects a particular lat.i.tude simultaneously, or approximately so. If this had to travel eastward to reach New York, it would have been the 10th instead of the 8th. The princ.i.p.al trouble was, however, in the early part of the evening of the 8th, to the south of Ottawa, where the strong wind was drawn in from the northward. If a vortex pa.s.ses from north to south, leaving the observer between the pa.s.sages, there must, nearly always, be a winding up squall from the north to clear away the vapory atmosphere.
[20] From the _New York Tribune_, July 9, 1853.
[21] These pages are now in the compositors' hands, (Nov. 21st,) and up to the last moment the Author has observed carefully in New York the pa.s.sages of these vortices. October 24th, in the inner vortex descending produced a violent storm on the coast, and much damage ensued. November 7th, the same vortex ascending was also severe. And on November 13th, early, the pa.s.sage of the central vortex ascending, caused a flood in Connecticut of a very disastrous nature. Would it not pay the insurance offices to patronize such investigations in view of such palpable facts as these?
SECTION THIRD.
OBJECTIONS TO LUNAR INFLUENCE.
We have now presented a theory of the weather, which accounts for many prominent phenomena, a few of which we shall enumerate. It is an observed fact, that in all great storms electrical action is more or less violent, and that without this element it seems impossible to explain the velocity of the wind in the tornado, its limited track, and the formation of large ma.s.ses of ice or hail in the upper regions of the atmosphere. It is also an observed fact, that the barometer is in continued motion, which can only be legitimately referred to a change in the weight of the atmospheric column. This we have explained as due to atmospheric waves, caused by the greater velocity of rotation of the external ether, as well as to the action of the three great vortices.
These causes, however, only partially produce the effect--the greater portion of the daily oscillations is produced by the action of the great radial stream of the solar vortex, as we shall presently explain. It is an observed fact, that, although the storm is frequently violent, according to the depression of the barometer, it is not always so.
According to the theory, the storm will be violent, _ceteris paribus_, on a line of low barometer, but may still be violent, when the contrary obtains. Another fact is the disturbance of the magnetic needle during a storm. Storms are also preceded generally by a rise in the thermometer, and succeeded by a fall; also by a fall in the barometer, and succeded by a rise. It is also well known, that hurricanes are unknown at the equator, and probably at the poles also. At all events, they are rare in lat. 80, and, according to Capt. Scoresby, storms are there frequently raging to the south, while above, there is clear sky and fine weather, with a stiff breeze from the northward. The greater violence of storms in those regions where the magnetic intensity is greater in the same lat.i.tude, the probable connection of peculiarities in the electric state of the atmosphere with earthquakes, and the indications of the latter afforded by the magnet; the preponderance of westerly winds at a great elevation in every lat.i.tude on the globe visited by man; and the frequent superposition of warm layers of air above cold ones at those elevations, are all facts worthy of note. And the connection of cirrus clouds with storms, as well as with the aurora, indicates that the producing cause is external to the atmosphere, and gradually penetrates below. The theory fully explains this, and is confirmed by the fantastic wreathings and rapid formation of these clouds in straight lines of a hundred miles and upwards. But time would fail us in pointing out a t.i.the of the phenomena, traceable to the same cause, which keeps our atmosphere in a perpetual state of change, and we shall only advert to one more peculiarity of the theory. It places meteorology on a mathematical basis, and explains why it is that a storm may be raging at one place, while in another, not very remote, the weather may be fine, and yet be dependent on the position of the moon.
That the moon has exerted an influence on the weather has been the popular creed from time immemorial; but, ignorant of the mode in which this influence was exerted, men have often been found who have fostered the popular belief for their own vanity or advantage; and, on the other hand, philosophers have a.s.sailed it more by ridicule than by argument, as a relic of a barbarian age. Not so with all; for we believe we are not wrong in stating, that the celebrated Olbers compared the moon's positions with the weather for fifty years, before he gave his verdict against it. He found the average amount of rain at the perigee about equal to the amount at the apogee, as much at the full as at the change, and no difference at the quadratures. But this fact does not throw a feather in the scale by which this theory is weighed. Popular opinions, of remote origin, have almost always some foundation in fact, and it is not much more wise to reject them, than to receive them. The Baron Von Humboldt--a man possessing that rare ingredient of learning, a practical common sense--observes: ”That arrogant spirit of incredulity which rejects facts, without attempting to investigate them, is, in some cases, more injurious than an unquestioning credulity.”[22] If a popular belief or prejudice be absurd, its traditional preservation for a thousand years or more may very well account for the absurdity.
The present system of astronomy still retains the motley garniture of the celestial sphere, as handed down from the most remote antiquity; and granting that ages of ignorance and superst.i.tion have involved the history of the different constellations in a chaos of contradictory traditions, there is no doubt at the foundation some seeds of truth which may even yet emerge from the rubbish of fable, and bear fruit most precious. That the zodial[23] signs are significant records of something worthy of being preserved, is prejudice to deny; and we must be allowed to regard the Gorgons and Hydras of the skies as interesting problems yet unsolved, as well as to consider that the belief in lunar influence is a fragment of a true system of natural philosophy which has become more and more debased in postdiluvian times. Amongst those who have not summarily ignored the influence of the moon, is Toaldo, a Spanish physicist, who endeavored to show the connection between the recurrence of warm and cold seasons, and the semi-revolution of the lunar nodes and apogee, and proposed six of those periods, or about fifty-four years, as the cycle in which the changes of the weather would run through their course. According to the present theory, it is not likely such a cycle will ever be discovered. There are too many secular, as well as periodic influences combining, to produce the effect; and the times are too incommensurable. Lately, Mr. Glaisher has presented a paper to the Royal Society, giving about fourteen years from observation. Others have lately attempted to connect the changes of the seasons with the solar spots, as well as with the variations of the magnetism of the earth, but without any marked result.
It may, however, be urged, that if the sidereal period of the moon be approximately a cycle of change, it would have been detected long ago.
One reason why this has been so long concealed, is the high lat.i.tude of the observers. Spain, Italy, and Turkey, are better situated than other European countries; but the scientific nations lie further north; and from these the law has gone forth to regulate more southern lands. In the United States, particularly in the great plains of the west, the weather can be better compared; not only on account of the lat.i.tude being more favorable, but also on account of the greater magnetic intensity of the western hemisphere.
It must also be remembered that there are in lat.i.tude 40, five or six distinct pa.s.sages of the disturbing cause in one sidereal period of the moon. If two of these periods are drawn closer together by the change of the elements, the interval between two others must necessarily be increased. Besides, the effect produced is not always the same, for reasons already adverted to. One vortex may be more violent one month, or for a few days in one month, while another may be more active the next. It may also happen that for several successive pa.s.sages, the pa.s.sage shall be central in one lat.i.tude, while two or three degrees north or south, another place shall be pa.s.sed by. In different months and in different years, as well as in different seasons of the year, the energy of the ether may be augmented or diminished. But it may be said, that, supposing the theory true, if its indications are so uncertain, it is of little value. By no means. It is true there are many things to be inquired into; but it is a great thing in this science to be able to take the first step in the right direction,--to find even the _key_ of the portal. It is a great stride to be able to say, a storm may happen at such a time, but cannot happen at another; that a storm, when raging, will go in this direction, rather than in that; that it will be central here, and less violent yonder; and when we consider its bearing on astronomical and other science, it is difficult to exaggerate its value to the world at large.
Again, it may be said that rain, and cloudy days, and fresh breezes, and even strong winds, sometimes occur, when the vortices do not pa.s.s centrally. This is true; yet only indicating that where the vortices are central, an unusual disturbance is taking place. But there is another cause, which was purposely omitted in considering the prominent features of the theory, in order not to enc.u.mber the question with secondary influences. By referring to Fig. 3, section 1, we see that the lateral vortices of the globe are continually pa.s.sing off to the southward, in the northern hemisphere, in a succession of dimples, and continually reforming. We will now represent this mode of action in profile, as it actually occurs in the ill.u.s.tration we have used.
The vortex pa.s.sing off from O, (Fig. 20,) although it does not actually reach the surface of the atmosphere, affects the equilibrium of the ether, and, for a short distance from the parent vortex, may cause an ascensional movement of the air. If to this is conjoined a northerly wind from the vortex, a band of clouds will be produced, and perhaps rain; but violent storms never occur in the intervals, except as a steady gale, caused by the violence of a distant storm. Thus, it will frequently be noticed that these vortices are flanked by bands of clouds, which pa.s.s southward, although the individual clouds may be moving eastward. Hence, instead of disproving the theory, they offer strong evidence of its truth; and could we view the earth from the moon with a telescope, we should no doubt see her beautifully belted.
[Ill.u.s.tration: Fig. 20]
But it may be again asked, why should not the weather be the same generally, in the same lat.i.tude, if this theory be true? If the earth were a globe of level land, or altogether of water, no doubt it would be similar; but it must be remembered, that both land and water are very unequally distributed: that the land is of varying extent and elevation--here a vast plain, far removed from the ocean, and there a mountain chain, interposing a barrier to the free course of the atmospheric currents; sometimes penetrating in full width into the frigid zone, and again dwindling to a few miles under the equator. One very important distinction is also to be remarked, in the superficial area of the different zones, reckoning from the equator, and taking the hemisphere as 100 parts:
Frigid zone 8 parts.
Temperate ” 52 ”
Torrid ” 40 ”
For as the time of rotation in every lat.i.tude is the same, the area to be disturbed in the same time, is less in high lat.i.tudes, and there a greater similarity will obtain, _ceteris paribus_. In lower lat.i.tudes, where both land and water stretch away for thousands of miles, it is not wonderful that great differences should exist in the electrical and hygrometric state of the air.
The summer of many countries is always dry--California for instance. In winter, in the same country, the rains are apparently incessant. This of course depends on the power of the sun, in diverting the great annual currents of the atmosphere. As long as the dry north-west trade sets down the coast of California, the circ.u.mstances are not favorable for giving full development to the action of the vortices. When the trade wind ceases, and the prevailing winds come from the south, loaded with vapor, the vortices produce storms of any magnitude; but (and we speak from two years' observation) the pa.s.sages of the vortices are as distinctly marked there in winter time, as they are in the eastern States; and in summer time, also, they are very perceptible. The same remark applies to Mediterranean countries, particularly to Syria and Asia Minor; although the author's opportunity for observing lasted only from April to December, during one season. If we are told it never rains on the coast of Peru, or in Upper Egypt, it does not seriously militate against the theory. The cause is local, and the Samiel and the sand storm of the desert, is but another phase of the question, explicable on the same general principles. From the preceding remarks it will be seen, that in order to foretell the character of particular days, a previous knowledge of the weather at that particular place, and for some considerable time, is requisite; and hence the difficulty of laying down general rules, until the theory is more fully understood.
MODIFYING CAUSES.
We now come to the causes which are auxiliary and interfering. It is natural that we should regard the sun as the first and most influential of these causes, as being the source of that variation in the temperature of the globe, which alternately clothes the colder regions in snow and verdure. The heat of the sun undoubtedly causes the ether of the lower atmosphere to ascend, not by diminution of its specific gravity; for it has no ponderosity; but precisely by increase of tension, due to increase of motion. This aids the ascensional movement of the air, and therefore, when a vortex is in conjunction with the sun, its action is increased--the greatest effect being produced when the vortex comes to the meridian a little before the sun. This has a tendency to make the period of action to appear dependent on the phases of the moon, which being the most palpable of all the moon's variations, has been naturally regarded by mankind as the true _cause_ of the changes of the weather. Thus Virgil in his Georgics, speaking of the moon's influence and its signs:
”Sin ortu in quarto (Namque is certissimus auctor) Pura, nec obtusis per clum cornibus ibit; Totus et ille dies, et qui nascentur ab illo, Exactum ad mensem, pluvia ventisque carebunt.”
Hence, also, in the present day we hear sailors speak of the full and change, or the quartering of the moon, in connection with a gale at sea; thus showing, at least, their faith in the influence of the phenomenon.