The continual influx of cosmical matter into the heart of the vortex in
ever-varying quantities, and speedily dispersed along the central plane,
according to its density, must necessarily give rise to another
phenomenon to which we have not yet alluded. Scarcely a night passes
without exhibiting this phenomena in some degree, and it is generally
supposed that the hourly average of shooting stars is from five to ten,
taking the whole year round. The matter composing these meteors we
regard as identical with that mass of diffused atoms which forms a
stratum conforming to the central plane of the vortex, and whose partial
resistance to the radial stream occasions that luminosity which we call
the zodial light. These atoms may coalesce into spherical aggregations,
either as elastic gas, or as planetary dust, and, passing outward on the
radial stream, will occasionally become involved in the vortex of our
own globe; and being drawn inwards by the polar current, and acted on by
the earth's gravity, be impelled with great velocity through the
rarefied air of the upper atmosphere. That meteors are more abundant
about the time of meridian passage of a vortex (or, perhaps, more
correctly speaking, from six to twelve hours afterwards, when the
current of restoration penetrates the atmosphere), well accords with the
author's observations. It is about this time that high winds may be
looked for, according to the theory; and it has ever been a popular
opinion, that these meteors are a sign of windy weather. Even in
Virgil's time, the same belief prevailed, as a passage in his Georgics
would seem to indicate.
"Sape etiam stellas, vento impendente, videbis
Praecipites coelo labi; noctisque per umbram
Flammarum longos a tergo albescere tractus;"
Virgil was a close observer of nature, and commences a storm with the
wind at south, "Quo signo caderent Austri;" just as we have represented
the usual course when these vortices pass near the observer's latitude.
It is also a well-known fact, that after a display of meteors, (and we
are now speaking of ordinary displays, and not of the great showers,)
the temperature falls considerably. It is not uncommon also, that
meteors are more abundant during an auroral display, as they ought to be
by the theory. We must, however, exempt from this influence those solid
meteors which sometimes come into collision with the earth, and
afterwards grace the cabinets of the curious. These bodies may be
considered microscopic planets, moving in stated orbits with planetary
velocity, and bear strongly on the explosive theory of Olbers, as fully
detailed by Sir David Brewster.
It is a very remarkable fact, first noticed by Olbers, that no fossil
meteoric stones have yet been discovered. If this fact be coupled with
the hypothesis advanced by Olbers, in reference to the origin of the
asteroidal group, we should have to date that tremendous catastrophe
since the deposition of our tertiary formations, and therefore it might
possibly be subsequent to the introduction of the present race into the
world. May not some of the legendary myths of the ancient world as
mystified by the Greeks, have for a foundation the disappearance of a
former great planet from the system? The idea of the existence of seven
planets is one of the oldest records of antiquity; but the earth of
course would not be counted one, and therefore in after times, the sun
was included to make up the number; just as the signs of the Zodiac have
been explained in accordance with the seasons of far later times than we
can possibly assign for the invention of this division of the heavens.
Let those who have the leisure, try how far the contraction and dilation
of the asteroidal orbits, to some average mean distance, will restore
them to a common intersection or node, as the point of divergence of the
different fragments. The question is interesting in many of its aspects,
and may yet be satisfactorily answered.
The composition of aerolites may also be taken as indications of the
common origin and elementary texture of the planets, whether they are
independently formed or have originally pertained to a former planet;
for no hypothesis of telluric or selenic origin yet advanced, can stand
against the weight of evidence against it. Their fragmentary character
rather favors the views of Sir David Brewster, and when we consider that
they have been revolving for thousands of years with planetary velocity,
and in very eccentric orbits, through the ether of space, continually
scathed by the electric blast of the radial stream, their rounded
angles, and black glossy crust of an apparently fused envelope, may be
accounted for, without difficulty, from the non-vitrified appearance of
the interior. The composition of aerolites as far as known, embrace
nearly one-third of all known simple substances according to Humboldt,
and are as follows: iron, nickel, cobalt, manganese, chromium, copper,
arsenic, zinc, potash, soda, sulphur, phosphorus, and carbon.
The theory we have thus given of the common occurrence of shooting
stars, will render a satisfactory general account of their sporadic
appearance; but there are other phenomena of greater interest, viz.: the
occasional recurrence of swarms of such meteors, which defy all
numerical estimates, being more like a fiery rain than anything they can
be compared to. The most interesting feature of this phenomena, is the
_apparent_ periodicity of their return. In the following table we have
set down the most remarkable epochs mentioned by Humboldt, (and no man
has devoted more attention to the subject,) as worthy of notice:
About April 22 to 25
" July 17 to 26
" August 9 to 11
" November 12 to 14
" November 27 to 29
" December 6 to 12
Besides these, he mentions two showers, from Arabian authority, in
October; one in October, observed in Bohemia; one observed by himself,
in the Pacific, on March 15; one February 4, just preceding the terrible
earthquake of Riobamba, in 1797. The Chinese annals also contain many
showers of stars, before the present era commenced. Some were in March,
more in July, and others in different months. How, then, in view of
these numerous dates, can we attach so much importance to the
periodicity of these showers? The great shower of 1833, in the United
States, on the 12th and 13th of November, brought to mind the great
shower at Cumana, observed by Humboldt and Bonpland just thirty-three
years before, to a day; and it must be confessed that more than ordinary
displays have been seen on this date. Yet, on the strength of this,
every meteoric shower is supposed to be periodical, and has resulted in
a theory which becomes more complicated as the phenomenon is more
observed, and can never lead to any useful and practical results. To
cite the numerous instances of discrepant results, would only encumber
this brief notice with facts neither interesting to the general reader,
nor convincing to those who hold a contrary opinion. The author of these
pages has watched for many years, and, in view of all the facts, has
concluded that the doctrine of periodicity (as held by present
meteorologists) is not tenable. The celebrated August shower failed,
also, this year, at least in this place, as for four hours each night,
on the 9th, 10th, and 11th, there were fewer bright meteors than at the
close of July.
Professor Olmsted, who has paid considerable attention to the subject,
has indeed attempted to connect the great November shower with the
zodial light, which last he considers a nebulous body, of an elongated
form, whose external portions, at this time of the year, lie across the
earth's path. (See Silliman's Journal for 1837, vol. xxxiii. No. 2,
p. 392.) He even gives its periods, (about six months,) the aphelion of
the orbit being near the earth's orbit, and the perihelion within
Mercury's. In this way he attempts to explain both phenomena; but as the
zodial light is seen unchanged all the year round in tropical latitudes,
it is not the kind of body supposed by Olmsted, and the theory adds
nothing to our knowledge. Others have imagined rings of nebulous matter,
in which all the separate parts are moving in the same orbit around the
sun, with a retrograde motion, and this, with some modifications, is the
current theory of the day. The principal arguments rested on, for the
support of this view, are derived from the great shower of 1833, in
which a common radiant point was observed, and confirmed subsequently by
the radiant of other years, in the same month of November. As this point
is almost tangential to the earth's orbit at this season, the earth
meets the nebulous ring moving in the contrary direction, and thus
confers on these meteors the necessary velocity that is thought to be
demanded by observation.
Now, our theory gives a totally different explanation of the phenomenon.
We contend that a retrograde motion of such a nebulous mass, is
subversive of our whole theory; and we must be permitted to examine
certain points, hitherto disregarded by those entertaining antagonist
views. It is supposed that the meteors in 1833 fell for eight or nine
hours. The orbital velocity of the earth is more than 1,000 miles per
minute, and the orbital velocity of the nebulous zone must have had a
similar velocity. During the nine hours of meteoric display, therefore,
the earth traversed 500,000 miles of her orbit, which would give
1,000,000 miles for the depth of the nebulous stratum. But if of such
vast extent, how happened it that the only part of the earth in which
these were visible in great density, was the United States, or a space
embraced between the latitudes of 50d and 20d north, and the longitudes
60d and 100d west, (and these are the widest limits,) comprising only
1/40 of the surface of the globe? To a calm inquirer, this difficulty
seems insurmountable. The author was then in the Mediterranean, on deck
the greatest part of the night,--the weather fine, and nothing unusual
visible in the heavens; from other sources he has also derived similar
information. Yet, were the earth then passing through a stratum of
meteors 1,000,000 miles in extent, it is utterly inconceivable that
other portions of the earth escaped. Much stress is also laid on the
fact that these meteors in 1833, passed from east to west generally, as
they ought to do, if tangential to the earth in her orbit; but on the
same phenomenon occurring in 1799, when the earth was in precisely the
same part of her orbit, Humboldt says distinctly, "the direction (of the
meteors) was very regular from north to south." How could this possibly
happen, and at the same time be moving tangentially to the orbit?
There is also another fact of importance not duly weighed in forming
such a theory. In 1833 the meteors evidently differed in velocity; one
class, consisting of luminous points, passed like a shower of fire with
great velocity to the westward, another class were like large fire-balls
with luminous trains moving with less rapidity, while a third class
consisted of nebulous patches which remained stationary for a long time,
and frequently emitting large streams of light. These last, at least, do
not deport themselves as planetary bodies moving 2,000 miles per minute.
But the fact still remains, that unusual displays have occurred about
the 12th and 14th of November; and also as a general thing when there
are no unusual displays, the meteors are more abundant about this time.
Let us try if we can reconcile these facts with the theory of vortices.
We will first confine our remarks to the increased number of meteors
about November 12th and 14th. The cosmical matter composing the zodial
light, or at least the lighter parts of it, is continually driven
outwards by the radial stream, just as the matter of a comet's tail is
stripped from the nucleus. This matter becomes involved in the terral
vortex by descending the poles, and is again passed out along the
equatorial plane. The form of the zodial light, as seen edgewise, gives
a lenticular form for the stratum of planetary particles composing it,
and its central plane has been considered as coinciding with the plane
of the sun's equator. At the orbit of the earth, this lenticular space
is narrowed to a very thin stratum, but undoubtedly reaches beyond the
earth's orbit with a rapidly diminishing density. As the axis of the sun
is inclined about 7d to the ecliptic, and the ascending node is in the
20th degree of Gemini, the earth can only pass through the plane of the
sun's equator about the 12th of December and the 12th of June. If,
therefore, the central plane of the vortex coincides with the plane of
the sun's equator, meteors ought to be more numerous about the dates
above mentioned. But the observed times are on November 12th and 13th.
Now, from actual measurements, a computation has been made by M.
Houzeau, that the elements of the zodial light are materially different
from those of the sun's equator. He fixes the node of the light
(according to Mr. Hind) in 2d heliocentric longitude, subject to an
uncertainty of 12d or 13d, and its inclination to the plane of the
ecliptic, 3d 35', subject to an uncertainty of about 2d. The truth is,
astronomers have argued the coincidence of the two planes from
considerations connecting the zodial light with the sun's equator, as if
it were a solar atmosphere; but such an atmosphere is impossible, and it
is high time such measures should be taken as will lead to some certain
conclusion. If in the present state of the question, we were to take the
mean, we should find the node in about longitude 40d, which is the
position of the earth on November 2d. But in the absence of
measurements, we will assume, for the sake of argument, that the
ascending node of the central plane of the vortex was, in 1833, in 50d
heliocentric longitude, and consequently the earth was passing through
the meteoric stratum or central plane of the zodial light, on the night
of November 12th. The opposite period of the year is May 12th--a date,
it is true, on which no great shower of stars is recorded, but sporadic
meteors are very plentiful at that time, and what is more important to
observe is, that the 11th, 12th, and 13th of May, are the three noted
_cold days_ which we have before mentioned. Thus truly indicating that
the earth is then in or near the central plane of the vortex along which
the radial stream is at its maximum of power at any given distance from
the axis.
But the question occurs, does the node of this plane remain stationary,
and is there no variation of the inclination of the axis of the solar
vortex? We have found from observation, that the axis of the terral
vortex is continually oscillating about a mean position by the action of
the moon; and reasoning from this analogy, and the constant tendency of
a material vortex to preserve a dynamical balance, the same tendency
must obtain in the solar vortex under the action of the great planets,
whose orbits do not coincide with the central plane of the vortex. The
ascending node of Jupiter's orbit is in longitude 98d, Saturn's 112d,
Uranus' 72d, Neptune's 131d; so that this plane does not correspond with
the plane of greatest inertia discovered by La Place, and from the
non-coincidence of these planes with the central plane of the vortex,
must produce the same oscillation in the axis of the solar vortex, as
the moon does in the terral vortex, but to what amount, observation can
alone determine. Jupiter and Saturn will of course exert the greatest
influence, and when these two planets are in conjunction, the ascending
node of the central plane of the vortex will vary in longitude perhaps
sufficiently to bring the meteoric maximum at the ascending node into
October on the one hand, and to the close of November on the other, and
at the descending node to April 25th on the one hand, and the close of
May on the other.
The great showers of stars which have been recorded, must be therefore
considered as an accidental exaggeration of a perennial phenomenon,
attaining its maximum when the earth passes through the central plane of
the vortex, whose ascending node in 1833 we will suppose was in
longitude 50d. This theory will therefore account for those great
showers which have occurred about the 24th of April, as well as those
occurring in October and November; for it is far more consonant to all
analogy, to suppose the influx of planetary atoms into the solar vortex
to be in irregular, than in regular quantities. Yet, whether in the one
case or in the other, the matter will pass along the central plane of
the vortex, either diffusely scattered or in denser clouds, and will be
encountered by the earth when near the nodes _more frequently than at
other times_. The phenomenon of 1833, may then be attributed to the
earth encountering an unformed comet on the 12th of November; but we
must reflect, that the medium of the vortex is also in motion, and the
cometary matter drifting along with it; and that this motion corresponds
with the earth's motion. By becoming involved in the terral vortex, it
will in a measure be carried along with the earth in her orbit as a
temporary occupant of the terral vortex. But we are here met with the
objection that the radiant being nearly stationary amongst the stars,
demonstrated conclusively, that the source of these meteors did not
partake of the earth's motion. There is no difficulty in this. We
suppose as a general thing, that the meteors descended to the surface of
our atmosphere down the axis of the vortex (at least in the greatest
numbers), and the geocentric longitude of this axis was nearly the same
during the whole time of the display. We say nearly, for the motion of
the moon in her orbit in nine hours, would change the longitude of the
axis three or four degrees, and this is about the change in the
position of the radiant noted at the time. This objection, therefore,
falls to the ground; for the axis of the vortex, although carried along
with the earth in her orbit, was unaffected by the earth's rotation, and
would therefore appear nearly as stationary in the heavens as Gamma
Leonis. But it is again urged, that the moon was near conjunction with
the sun, and consequently the central vortex was on the opposite side of
the globe. This is true; but the outer vortex must have been near the
meridian about three hours after midnight, or about the time when the
radiant was vertical and the display the greatest. When the axis was to
the eastward, the stars would shoot westward, when on the meridian, they
would pass in all directions, but principally to the south, on account
of the inclination of the axis of the vortex; but this would only be
true for places situated to the southward of the central latitude.
During the great shower of stars seen by Humboldt, in Cumana, the
direction was to the south uniformly. Now, the latitude of Cumana is
above 10d north, yet still too low for the general limits of the
vortices; but from the same inclination of the axis (from 30d to 36d to
the surface), the meteors would pass far south of the limit, and might
even reach to the equator. The latitude of the _outer vortex ascending_
on November 12th, must have been near the line of greatest display, from
the position of the moon at the time. We thus see why the phenomenon was
limited to so small a fraction of the earth's surface; why these meteors
should be intermingled with nebulous patches stationary in the heavens
for an hour together, and why, notwithstanding these facts, they were
independent of the earth's rotation.
We have yet another objection to answer, viz.: the planetary velocity of
some of these bodies. Let us be understood. The velocity of a solid
aerolite is due to gravitation, and is planetary, on the other hand,
voluminous collections of cometary dust united by accident, and
remaining so by mere inertia, are borne passively on the ethereal
currents with _electric_ velocity, and probably never penetrate far,
even into the attenuated atmosphere, which may be supposed (from the
facts connected with the aurora) to extend far above the denser stratum
which refracts and reflects light, and from which the assigned limits of
our atmosphere have been derived.
It is generally considered that sporadic meteors are more numerous in
the summer and autumn than in the winter and spring, and we have,
likewise, in the tenth of August, a date which corresponds to many great
displays and meteoric showers, both in recent and remote times. This
would seem to vitiate our theory; for we cannot suppose that there are
two _central_ planes in the vortex intersecting the ecliptic in
longitude 320d and 50d. We must remember, however, that as these great
displays are accidental, and as the stratum composing the zodial light
is manifestly of sufficient thickness to envelope the whole orbit of the
earth, that it does not necessarily follow that the dense portions to
which meteoric showers are due, should be always confined to the central
plane of the vortex. And, besides, we have similar displays recorded in
other months, which invalidates the theory of a regularly-recurring
phenomenon. We shall, therefore, only aim at explaining why meteors are
generally more abundant in summer and autumn than in the opposite
seasons.
The axis of the solar vortex, considered as cylindrical, must be
admitted to run out to a great depth on either side from the sun, and
reach far into that unoccupied space intervening between our system and
the nearest fixed stars, and from these opposite points the solar vortex
is supplied with that stream of ether which passes down either pole to
restore a partial equilibrium in the density of the ether of the vortex,
rarefied by centrifugal force. As certain portions of the heavens are
crowded with stars, and other parts comparatively vacant, we may expect
a similar inequality in the distribution of that cometic dust, which
causes a certain amount of extinction in the light of the stars, and,
therefore, seeing that the two extremities of the axis of the solar
vortex are so widely separated, it would not be wonderful if different
quantities of such matter were brought down into the vortex from these
extremities.
From recent observations made by H. R. Birt, at the observatory of the
British Association, it would appear that the brightest portion of the
zodial light is always north of the ecliptic. Others have also remarked
the same, and if we couple this fact with the suggestion just made, we
are justified in suspecting that a greater quantity of cometic dust
comes down the northern pole of the vortex than down the southern. This
matter, in passing outward, does not, of course, immediately attain to
the central plane of the vortex, but is more thickly distributed along a
plane parallel to this plane. And the same will be observed by that
matter coming down the southern pole; it will be, in a certain degree,
retained in a plane south of the central plane, but still parallel with
it. This would account for the greater brightness of the northern side
of the zodial light. It would, also, account for the greater frequency
of meteors in summer and autumn than in the opposite seasons. From May to
November the earth is above the central plane of the vortex, and,
consequently, on the northern side; but after passing the node in
November, she is on the under or southern side, and the meteors are less
frequent. With this general explanation we shall close. If what we have
advanced be an approximation to the truth, the theory itself affords
ample indications of what observations are requisite to prove or
disprove it; and, on this account, a theory is of great benefit, as
suggestive of many questions and combinations of facts which otherwise
might never be thought of.
We have thus taken a cursory glance at the prominent physical phenomena
of the world, and attempted to link them together in the bonds of one
all-pervading principle. We have fearlessly taken a new path, and claim
originality for the whole, disclaiming all intention of retailing
second-hand wares, or of compiling an ingenious theory from
heterogeneous scraps. If it be true, or if it be partially true, let
those professionally engaged in such pursuits enter the wide field of
investigation we have discovered for them; for if the whole theory be
true, it only shows in a clearer light that the great work which has
been fancied so near completion is scarcely yet begun; while the
prospect of an ultimate and final completion of the temple which so many
zealous votaries are erecting, is rendered mournfully hopeless by the
contemplation of what yet remains to be performed.