THE GENESIS OF SOLAR SYSTEMS AND GALAXIES.
The processes of development of a solar system from the diffused
elemental matter of space may then be roughly sketched as follows,
premising that each stage may have possibly extended over vast periods
of time, and the whole, perhaps, not been completed for millions of
years. With the processes of creation time is as nothing.
The area of space in which a solar system is about to be developed has
hitherto maintained its molecular constituents in a state of gradually
increased unstable equilibrium, whether such augmented instability
may have been induced by a gradual rise of temperature from emission
of the solar energy of other galaxies, by gradual diffusion from
constantly operative centers, from currents or vortices of space,
or by some primal inherent constitution of space itself, with
constantly increasing tensions relieved by successive discharges,
of which analogous instances are found in various other processes
of nature, as, for example, ovulation, fission, and gemmation in the
reproduction of life, regularly recurring epileptiform convulsions,
regularly repeated spark discharges from electrical machines, or the
ebullition of viscous fluids with their slowly recurring bursting
bubbles. At some focal point of this area a rupture of tension will
finally occur, induced by some sudden current or vortical movement,
as we see sometimes in a pool of water gradually reduced in temperature
below the freezing-point, when its whole surface, by the passage of a
breath of wind even, will be suddenly flashed into crystals of ice. At
this point of space there will be instituted a rapid expansion among
the molecules and a consequent fall of temperature, followed by an
inrush of the vaporous material surrounding this center of agitation,
and a vortical movement will be established, with currents of spatial
matter attracted to this vortex in constantly increasing streams. The
molecular tensions will be successively unlocked as the circles of
agitation continue to widen, and a condensed nucleus will form,
rotating upon its axis and exhibiting the combined phenomena of
gravity and centrifugal force. As the nucleus continues to increase
in mass and density its temperature will constantly rise, while its
speed of rotation will gradually diminish as its volume increases,
and the aqueous vapors of space, as they gather around this rotating
center of attraction, will be forced outward by centrifugal action
and the heat of the nucleus, and form vast attenuated clouds,--not
necessarily visible, however, to human sight,--and these clouds, in
their various stratifications and disturbances, will gradually come
to partake of the rotatory movement of the center, such movements,
however, gradually fading away as they recede in space and in
density. The cyclonic movements of these clouds of aqueous vapor
upon themselves, but principally against the surrounding gases of
space still under tension, will generate enormous quantities of
electricity, which flash like thunder-clouds as they approach each
other, with incessant streams of lightning and rolls of thunder. The
growing and heating central nucleus is thus thrown into a state of
high electrical opposite polarity, and its own constituent elements
become self-repellent, just as we see in the sun's corona and in the
phenomena of comets. The electrical tension of the central mass will
gradually grow higher and higher, until a vast stream or streams
of incandescent nebulous matter (for with double suns they may be
multiple, or the internal repulsion may even cause division of the
nucleus itself) will be suddenly driven outward in a radial direction
along the lines of least resistance,--that is to say, in the plane of
equatorial rotation, where centrifugal force is most effective. We
can readily understand the self-repellent force of such an enormous
mass of cosmical matter by considering that, in our own completed
system, the repulsion of the solar electrosphere drove forth the tail
of Newton's comet, as before stated, to a distance of ninety million
miles, and whirled it around a semicircle of this radius in less than
four days. Our most distant planet, Neptune, is only thirty times
this distance from the sun, and we see during every solar eclipse
the coronal structure glowing to a distance of more than a million
miles from the sun's disk, and the radial streamers driven forth
five million miles, and even farther. (See illustrations of solar
corona in Guillemin's "The Heavens.") The vast stream of radiating
nebulous matter thus forced out by solar repulsion will likewise
be acted upon with equal energy by its own internal self-repellent
force. If we conceive a stream of water thrown vertically upward by
a powerful force-pump, in which every drop of the fluid is endowed
with tremendous self-repulsive energy, we should find an analogy
to the phenomenon in question. We can see an example of this in the
"Crab Nebula," illustrated in a previous chapter. The stream, acted
upon by gravity downward, by the force of ejection upward, and by the
internal force of repulsion both transversely and upward, would assume
a pyriform shape, narrower beneath, largely swollen about its middle,
and thence gradually decreasing in diameter to its termination in
a rounded tuft, in advance of which would be driven forth detached
sprays and wisps, while filaments and outlying parallel strands would
mark its entire ascent, except towards its point of ejection, where
the primal force which drove it out is greatly in excess of those
of gravity and self-repulsion. It will be seen at a glance that
these phenomena are precisely those which we observe in a comet's
tail. (See illustrations of many comets having these characteristics
in Guillemin's "The Heavens," Lockyer's edition.)
Suppose, now, that this stream of water or the tail of a large comet
were gradually wrapped around its point of emission by the rotation of
this nucleus upon its axis. A spiral would form, very open or flaring
at first, but gradually growing closer and more circular as the force
of gravity drew its convolutions downward upon the interstratified
clouds of aqueous vapor occupying, in compressed layers, the spaces
between the adjacent coils of the spiral. There would be a composite
action of forces observed: gravity would attract the convolutions
and their interstratified layers of cloud equally, according to
their densities, while the central repulsive force would repel the
convolutions of the spiral along the same lines of force, but would
not act at all upon the strata of clouds, and the force of internal
self-repulsion would also tend to disrupt the convolutions of the
spiral by expanding them outwardly. The outer convolution, however,
would have no backward thrust from any internal repulsion beyond,
while, within, gravity and solar repulsion would be more equally
balanced, so that the outer coil would be relatively compressed in
its rotation against the next inner convolution, and its ratio of
distance would not be maintained. We find this exemplified in the
case of Neptune's, orbit in our own system. The inner convolution
would also be abnormal, since the primal force of ejection must have
been sufficient to carry the outward thrust of the whole spiral,
and in consequence its flare would offer much greater resistance
to the deflection of rotation, and it would have a more radial
direction than those beyond. We shall find that the planet Mercury,
and the inner convolution which was eventually reabsorbed into the
solar mass, exhibit these phenomena. Between the outer and these inner
convolutions the curve of the spiral would be approximately regular,
with a fixed ratio of increase. In the planets of our solar system
this ratio is that produced by constantly doubling the preceding
number, the series being 0, 3, 6, 12, 24, etc. In other solar systems,
however, the ratio may be quite different. In this abnormal flare of
the inner convolution is doubtless to be found the rational basis of
Bode's empirical law of planetary distances, in which the arbitrary
number 4 must be added to each term of the above progression, making
the series 4, 7, 10, 16, 28, etc. The inner coil between Mercury and
the sun was drawn into the solar mass on the disruption of the spiral,
leaving, from the abnormally radial curvature of the inner portions
of the spiral and its absence from the series, a vacant place which
must be represented by the relatively fixed increment to be added to
each term of the series.
As the convolutions of the spiral become more and more compressed
towards each other and more and more flattened against the
interstratified cloud-layers, the force of internal repulsion becomes
more and more active in its tendency to disrupt the spiral, since its
forces are more direct and concentrated along lines nearly at right
angles to the force of gravity. During the formation of the spiral
we can easily conceive that--like a stream of water shooting over a
cascade, or the multiple tails of some comets, or even a whole comet,
as, for example, Biela's, which was split up into two separate bodies
by this force--some convolution, perhaps a single one of the series,
will be laterally divided into a large number of nearly parallel
strands, mutually held apart by their internal self-repulsion, and
with cloud-layers interposed between these lateral strands. Such a
series of small planets as these would finally produce we find in the
belt of our asteroids, the bulk of the convolution, probably, for the
most part, however, scattered in space, since their aggregate mass is
so small, and possibly, in part, coalesced into the mass of Jupiter,
to which Mars, by his position, may also have contributed.
Not only may a whole convolution be thus split up, but along the
spiral at many points the outer margins may be thrust outward,
forming partially detached parallel strands, which may thus coalesce
to form the satellites of the completed planets; while at the outer
extremity of all, where the backward thrust of self-repulsion is
wanting, enormous wisps, sprays, and tufts of nebulous matter would
be driven entirely forth into the illimitable realms of outer space,
but not necessarily, or even probably, into the space of other systems,
which are so enormously distant; and there, in those unoccupied realms,
they will remain to gyrate "in the solitude of their own originality,"
in the form of comets, until, at long intervals, they may chance
to revisit the scenes of their earliest youth, to warm their frozen
limbs for a brief period at the old and well-remembered parental fire,
or finally, worn out with toil and travel, "come home at last to die."
Driven forth from the society of their fellows by their own unbalanced
energies, these anarchists of the sky may form loose aggregations,
granulated about multitudes of self-constituted minor centers; but,
cut loose from all effective solar control during their period of
coalescence, they must forever lack the consolidated form and complex
organization of their prosperous and rotund brethren, the planets and
their satellites, or even the tiny asteroids, who stayed home and,
like the little pig, had bread and butter for breakfast.
The disruptive energy of internal repulsion, as above stated,
increases in force as the convolutions of the spiral become more
and more compressed and the spiral becomes more and more circular in
form. Suddenly the coils of the spiral will be burst asunder, and this
will occur along that particular radial line of gravitation where the
central nucleus acts with its most effective force. The disruption will
be simultaneous, as a general rule, in accordance with the principles
which control ruptures of tension of bodies in a state of unstable
equilibrium, and which we see exemplified in multiplied centers of
crystallization, the simultaneous formation of mud-cracks, the Giant's
Causeway, and other like phenomena. Each convolution will now become
a detached open ring, one of its broken extremities, however, being
millions of miles farther from the central nucleus than the other. What
occurs when a cometic body, negatively electrified, impinges upon the
positive electrosphere of a planet, or when an electrical induction
machine like Voss's is touched by an oppositely electrified body,
will now necessarily occur with these disrupted convolutions. Their
connection with the negatively electrified nucleus being broken,
a reversal of electrical polarity will ensue from contact with the
adjacent positively electrified clouds of aqueous vapor, and, instead
of self-repulsion, mutual attraction will now prevail along the length
of each of the open rings. Held apart from the central nucleus by
the interstratified cloud-layers, and acted upon by the double force
of gravity and internal attraction, the component elements of these
open rings will rapidly lose their luminosity and heat, and coalesce
by a retrograde movement down the lines of their direction, thus
approaching the sun along the segment of an ellipse, the nucleus, or
sun, occupying one of the foci, the eccentricity of the ellipse being
measured by the differential between the nearest point of the open
ring and the part of the convolution which lies directly opposite and
beyond the sun. In other words, the form of the spiral will determine
the eccentricity of the ellipse, subject to perturbations, however,
of various sorts. During this stage of coalescence from an open ring
into a sphere, these bodies will take on, by cooling and condensation,
their planetary forms; and as the forming spheres, by the retreat
of their masses down the lines of approach to the sun, advance,
their forward and nearer extremities will be more powerfully acted
upon by gravity than those parts in the rear, and a forward plunge
or axial movement of rotation will be set up. Viscous matter,--pitch,
for example,--molten by the sun's heat and flowing down a steep roof,
exhibits a similar forward movement, the outer layers tending to roll
over the inner ones in convoluted folds, the adhesion to the roof of
the under surface corresponding to the retarding pull of the sun's
attraction. In like manner are produced rotating eddies in streams
of water having crooked channels, eddies of air under water-falls,
and other analogous atmospheric disturbances. During the stage of
coalescence of the planetary spheres the adjacent clouds of aqueous
vapor will condense around them, and their hitherto diffused electrical
energies will be concentrated by rotation in currents of enormous
quantity and potential directly upon the sun, and a disassociation
of the elements which compose these watery vapors will ensue, the
result of which will be the deposit of hydrogen gas as an atmospheric
envelope around the sun's body, and of oxygen around and through the
bodies which constitute the planets. These gases will be disassociated
in their combining proportions, two volumes of hydrogen at the sun
for one volume of oxygen, distributed according to their relative
electrical energies among the planets. This nascent oxygen will
rapidly combine with the consolidating elements of the planets and,
interpenetrating their solidifying bodies, form the vast mass of
oxides which we find to constitute the bulk of our terrestrial mass,
the residue, mechanically commingled with the condensed ever-present
nitrogen, forming the planetary atmospheres. The condensation of volume
of the planets will give rise to great elevation of temperature,
while their currents of electricity, poured into the sun, will, by
their passage through its enormously compressed hydrogen atmosphere,
produce intense heat, and this, rapidly communicated to the solar
core within, will raise its temperature to that of the sun as we now
see it, and permanently maintain it in that state of incandescence.
During the stage of coalescence of the planetary bodies, outlying
strands of the spiral will follow the course of their adjacent masses
in a nearly parallel movement, and will gradually coalesce into smaller
bodies more directly under the influence of the gravity of their own
adjacent planets, by their proximity, than of that of the sun. These
bodies will thus rotate as satellites around their planets, and the
forward shift of their centers of gravity, by their advance along
their lines of coalescence, may result in a permanent displacement,
of which we see an example in the moon, which constantly presents the
same face to the earth, while having an axial rotation of its own with
reference to the sun. (In this case the action of gravity may have been
assisted, however, by the mutual repulsion of the lunar and terrestrial
electrospheres forcing the atmosphere and moisture of the lunar mass to
its opposite side and maintaining it there, where it would remain as a
buffer against rotation.) In some cases we might find certain outlying
strands of a convolution which, perturbed by external influences,
may have been delayed in its conversion into spherical form, and this
subordinate strand, pyriform itself, as it must have been, in shape,
would thus form a spiral of minute discrete bodies, probably like the
nucleus of a comet, finally assuming the shape of a series of rings,
and rotating like a satellite around the neighboring planet, the inner
and outer strands more attenuated and the middle ones more condensed,
as we find to be the case with the rings of Saturn.
In the original spiral we have seen that, as a whole, it was of
necessity pyriform in shape. The planets formed therefrom would thus be
found to increase in size from within outward to a maximum, after which
they would again decrease, but not to the original minimum, while the
extreme outer planet would also be unduly enlarged by increment from
partially dissipated terminal filaments, gradually attracted thereto
from surrounding space. There is such an undue enlargement of the
planet Neptune, and this, with its relatively compressed orbit, before
alluded to, renders it almost certain that Neptune is in reality the
outermost member of our planetary system. We find this gradation of
size to be the case in our solar system, except where the series has
been broken by the multitudinous separation, from violent internal
repulsion, of one of the convolutions into parallel strands showing
all sorts of perturbations, this being the convolution which occupied
the region between the orbits of Mars and Jupiter, and which, by the
coalescence of these numerous parallel strands into small planetary
bodies, has filled the space with a belt of asteroids hundreds and
perhaps thousands or even tens of thousands in number. It is probable
that a law regulating the ellipticity of planetary orbits can be
deduced from a consideration of the principles which have governed
their inception, and with these are doubtless closely related those
laws of Laplace which have demonstrated that "in any system of bodies
travelling in one direction around a central attracting orb, the
eccentricities and inclinations, if small at any one time, would always
continue inconsiderable." (Appleton's Cyclopædia, article "Planet.")
We have thus traced the genesis of a solar system from its earliest
stages forward through its various changes until, complete and in
working order, it is ready to be sent on its eternal course, either
alone or as one of a vast congeries of similar systems, like the
Milky Way. (See frontispiece for illustration of a series of types of
development from a straight-tailed comet, through different curvatures,
and spiral nebulæ of less and less divergence, until nearly circular,
and finally terminating in a complete solar system.) These processes
of creation may be isolated, or they may flash a hundred million solar
systems into being together, as crystals flash forth in the rock;
but, when once formed, they go forth each as eternal as space itself.
But can we not go back one step farther still in the progressive
stages of creative energy? Whence came these powerful agencies by
means of which all those distant regions became peopled with suns and
worlds? The great source of all is to be found alone in space,--the
so-called "empty space." But it is far from empty; all through it
are diffused the attenuated vapors which, condensed, constitute our
suns and planets, and all that is, or ever shall be, gaseous vapors,
which are held poised, with their opposite tensions of cohesion and
expansion, like the Prince Rupert drops which glass-blowers make
for toys,--a little bulb of glass, chilled as it falls, molten,
in a vessel of water. From one extremity projects a long, crooked
stem, scarcely thicker at the end than a horse-hair, spun out from
the molten glass as it hung from the glass-blower's rod. The bulbous
body is as large, perhaps, as a nut; you can beat it with a hammer and
it will not break; it is the hardest in structure of all glass. Now,
wrap this bulb up in a thick handkerchief, or you may be injured; hold
it firmly, and break off the very tiniest tip of the long stem three,
four, or even six inches from the bulb. There is a sudden shock; open
your handkerchief, and lo! instead of the solid bulb, there is only a
loose mass of white powder. If you put the bulb in a heavy glass vessel
full of water and break off the tip of the tail, it will shatter the
vessel into fragments. What is the explanation?--it is, of course,
well known--simply that the molecules of glass were instantly arrested
in their motion of adjustment as the glass was suddenly chilled by the
water, and the molecular motion of shrinkage was arrested, leaving
the individual molecules under a tremendous strain of position in
their endeavor to reach their true places. They are rigidly fixed
in this position of unstable equilibrium, one balancing the other;
but let a single molecule be displaced,--a fragment so tiny that
the eye can scarcely see it,--and the molecules, thus thrown out of
mutual support against each other, must now rearrange themselves from
the ruptured rigid mass, and, like a row of stood-up bricks, each of
which thrusts the other forward, with a sudden explosive force the
molecules assume their true position of stable equilibrium, but it
is at the cost of the whole structure. To this same cause we owe the
explosive force of our gunpowder, nitroglycerin, and all explosives;
the molecules are held in unstable equilibrium, and the tension once
relieved at a single point, be it ever so infinitesimal, the molecules
of the whole mass rearrange themselves with explosive energy. Strange
that so harmless a substance as glycerin, by the mere replacement of
an atom of nitrogen gas, should develop the energy of dynamite under
a trifling molecular shock.
So, also, the aqueous and perhaps other vapors of all space, attenuated
though they be, and perhaps by reason of this very tenuity itself,
as shown by the experiments of Professor Crookes with attenuated
gases when acted upon by electricity, are held in the same state
of unstable equilibrium. We know the potency of this instability
from the terrific explosive combination of the gases which combine
to form aqueous vapor. We may again refer to one of the well-known
experiments of Professor Crookes with simple atmospheric air. Enclosed
in a cylindrical glass vessel, the electric spark passed freely; as
it became more rarefied under an air-pump, new phenomena appeared,
until, at a stage of high rarefaction, the molecules of these gases
were driven forward by the electric current with such energy as
first to raise the temperature of the opposite side of the cylinder
to a red heat, then to melt, and finally to perforate the glass. The
explanation is that the movements of closely aggregated molecules
mutually interfere with each other; as they gain elbow-room by being
reduced in number, they act with more directness, and consequently
with more force: it is the difference between men fighting in a
crowded room and out in an open field. It is possible that these
molecular tensions of space, by the ready unlocking of the forces with
which they are charged, may even aid in the rotation of the planets
by acting upon their electrospheres in their drift through space,
as charged thunder-clouds react upon each other, or the molecules of
atmospheric air, in moderately high vacua, under electrical excitement,
act upon the walls of the containing vessel, as in the experiments
of Professor Crookes and others. The riddles of nature are like those
of the sphinx,--they have more than one meaning.
The tensions of the aggregated molecules of space are thus
counterbalanced only so long as all space is equally occupied and
a state of perfect quiescence exists in its every part. A molecular
disturbance in one part is immediately communicated to adjacent parts,
and finally to all. With the first movement, gravity asserts itself,
for gravity exists and must exist in all parts, and must actively
manifest itself whenever the perfect mutual balance of space is
disturbed and a center of energy developed, and co-ordinately with
the action of gravity begins that of electricity. Movements among
the molecules are converted into movement of mass; centripetal motion
begets condensation, this begets sensible heat and vortical movement;
then come the phenomena of electrical generation by moving contact with
the gases of space, then repulsion and disassociation of the elements
of the aqueous vapors, combination of simple into compound elements;
and, the balance once disturbed, the state of unstable equilibrium
is forever destroyed, and all space henceforth must exhibit constant
change. There are whole segments of space absolutely blank, so far as
visible systems are concerned, which seem to have been exhausted, for
the present æons at least, to supply material for the vast adjacent
galaxies which extend along their borders; see illustrations in
Proctor's "Essays on Astronomy," article "Distribution of the Nebulæ."
It need not be supposed that such stage of perfect and universal
quiescence ever existed in fact; it is like the Nirvana of the Buddhist
philosophers,--a subjective and not an objective condition. We can
have no knowledge of the existence, even, of material things, save
from their phenomena, the manifestation of interchanging forces,
upon which rests our threefold basis of knowledge, perception,
cognition, and comparison. We know nothing of matter, except as
affected by internal or external force, nor of force itself, except
as it acts in one mode or another upon matter. All beyond this is,
for us, without form and void.
Progressive change has always, doubtless, been the universal law of
creation, and the great ocean of space is, and ever has been, and
ever will be the highway through which perpetually plough the great
caravels which bear the fortunes of creative energy, laden with life
and light and heat, in their eternal progression. The creative impulse
once given, if it, too, was not primeval in the eternal past, must
have gone on from development to development, like the transmission
of life, from age to age and from realm to realm. "The mills of the
gods grind slowly;" in these vast areas time is absolutely nothing;
the processes we see are but as the dip of a swallow's wing compared
with an inconceivable futurity; but all our energies, and all the
energies of planets and suns and systems and galaxies, and of whatever
other and wider created forms may stretch onward to infinity, came
forth from the ocean of space, and to this ocean all these energies
continue to return again in ceaseless circuit.
Can we indicate any relationship of periodicity for the genesis of
solar systems from space? There is a remarkable example of a somewhat
similar periodicity in organic life for the rupture of tensions,
so common that its analogous character and perfect regularity are
scarcely even thought of. Among the highest species of mammalia we
find that, in a state of health, whether resident of the heights
of the Andes, the deserts of Africa, the jungles of India, or the
most densely populated centers of London; among rich or poor, high
or low, idle or industrious, virtuous or vicious, ancient or modern,
civilized or barbarous, black, white, red, or yellow, the ovum of the
mature female rises to the surface of the ovary, and at intervals,
almost uniform, of twenty-eight days, organic excitement ensues, the
enclosing vesicle is ruptured, and the ovum escapes. The remarkable
feature is not that these processes continuously succeed each other;
but that under such diverse conditions and opposite circumstances, and
with two separate ovaries operating at the same time, simultaneously or
successively, this almost miraculous interval of no more and no less
than twenty-eight days between the successive ruptures of tension and
their attendant phenomena, should constantly persist. For its ultimate
cause we must look back to the vis a tergo to which we have already
alluded; and there may be, and doubtless is, a similarly acting remote
cause which regulates the periodical development of solar systems or
of galaxies, periods of intense activity, followed by intervals of
exhaustion and recuperation, and again succeeded by another period
of activity, and so on perpetually, for space is perpetual, infinite,
and inexhaustible.
It will be observed that the processes above roughly sketched are
somewhat similar to those observed in the formation of so-called
water-spouts, which usually terminate in dissipation in the atmosphere,
or else in terrific thunder-storms, but which occasionally reach
a sufficient energy of rotation to spin their central nuclei down
towards, or even to, the surface of the sea, or, in desert regions,
to that of the ground. There is no analogy with the theoretical and
"assumed" primal mass of attenuated plasma of the nebular theory,
or with its slow initial rotation, with the successive casting off
of rings of nebulous matter. It may sometimes happen, however, that
the repulsive electrical energy of the central nucleus may throw off
its external envelopes with sufficient force to drive them entirely
beyond the effective limit of its attractive forces, as occurs
in the formation of embryonic comets as above described; in such
case the nebula will be a variable one, with successively repeated
aggregations and successive outbursts, periodical like the active
stages of volcanoes; and, even when the nucleus has already presented a
continuous solar spectrum, its energies may be thus expended, or more
gradually, and finally dissipated like the electricity of a highly
charged Leyden jar exposed to a moist atmosphere.
As a bottle of strongly effervescing liquid may blow itself empty,
when suddenly opened, by the mutually repellent energy of its
contained molecules, so if such a phenomenon were manifested in
a radial direction from a central point, the repelled spray would
show itself as a nebulous ring with a hollow center. An example of
this sort is shown in the multiple-tailed "Catherine-wheel" nebula
(Fig. 4 of a previous illustration). If such an annular nebula
should become ruptured into two portions by internal repulsion,
the electrical polarity of the smaller fragment would be reversed,
and the two arcs would separately coalesce and consolidate into a
sun and a single planet, forming a solar system like that of Algol,
which has been already described. Otherwise, the nebula would probably
retrograde and disappear, by diffusion, into space again. We may
expect to find abortive efforts of nature here, as we so constantly
find them elsewhere, not merely in inorganic matter, but even among
the processes of life.
In Professor Proctor's article ("Essays on Astronomy") on
the square-shouldered aspect of Saturn, he mentions a hitherto
unexplained circumstance of the earth's atmosphere--the curious fact
that the barometrical pressure of the earth's atmosphere is somewhat
higher between the poles and the equator than immediately over the
latter, as might be supposed to be the case. This is a phenomenon of
mutual repulsion similar to those manifested in the operations above
described. The rotation of the earth on its axis forces the terrestrial
atmosphere, by its centrifugal motion, in undue proportion, around
the equatorial belt, causing the same sort of atmospheric thinning at
the poles which we see in the solar photosphere at its corresponding
parts. At the same time the highly electrified atmosphere, by its
mutually repellent action, tends to force this swollen equatorial ring
backward toward the poles. The resultant of these two repulsions is an
area of maximum density part way between the poles and the equator. It
is probable that this self-repellent equatorial swell may play some
part in the sun's atmosphere, in extending, and also in limiting,
the areas of eruptive sun-spots outward from his equator.
While the nebulæ are more distant than many of the discrete stars
revealed to us by the telescope, there is no reason to suppose that
they are more distant than the star-clouds into which are merged
the separate stars of the Milky Way, or the star-clusters seen in
other portions of the sky. We know, in fact, that this is not so,
for our telescopes show brilliant stars in very many cases which are
components of the nebulæ themselves; and the fact that the nebulæ
can be seen as having visible form, and not as mere points of light,
is itself conclusive as to their relative distances. Hence we need
not be surprised to learn that these forming spirals will result each
in the production of a single solar system, and not a galaxy of suns,
as was once supposed. Were such the case it would be impossible for
us to observe the structure of the nebulæ at all, as their distances
would be far too vast. Of the forms of the gaseous nebulæ Guillemin
asks, "Is the spiral the original form of those gaseous matters,
the condensation of which may give, or has given, birth to each
individual of this gigantic association?" The same author says of
these apparently regularly formed nebulæ, "It is impossible not to
recognize in them so many systems." Many of the spiral nebulæ were
formerly supposed to be globular aggregations of nebulous matter only,
and their spiral character came as a great surprise with the use of
more powerful telescopes; and many--nay, most--of these apparently
globular nebulæ have totally changed their appearance when viewed
with instruments of higher power, while the spirals have become more
and more pronounced in character with every increase of telescopic
vision. Of one of such apparently globular nebulæ Guillemin says, "The
center is like a large globular nebula with a very marked condensation,
whence radiate branches arranged in the form of spirals. In several
points of these branches other centers of condensation are noticed. Sir
John Herschel had classed this among the nebulæ of rounded, globular
form, doubtless because the central nebulosity was the only one
revealed by his telescope." The formation of the sub-centers in
this nebula (which is between the Great Bear and Boötes) should be
particularly noted in connection with the coalescence of planets as
above described. In a note to Guillemin's work, Professor Lockyer
says, "The proper motion of nebulæ has not yet been inquired into,
because everybody, looking upon them as irresolvable star-clusters,
thought them infinitely remote. Now, however, that we know they are
not clusters of stars, properly so called, it is possible that they
may be much nearer to us than we imagine."
In connection with the double-sun spiral nebula shown in the preceding
illustration, Guillemin says, "We have noticed nebulæ accompanied
by systems of double or multiple stars, placed in a manner so
symmetrical in the midst of the nebulosity that it is impossible to
doubt the existence of a real connection between the stars and the
nebulæ." And Flammarion says of these apparently globular nebulæ,
when under the observation of more powerful telescopes, "In the place
where pale and whitish clouds gave out a calm and uniform light, the
giant eye of the telescope has discerned alternately dark and luminous
regions,"--that is to say, they reveal the operation of the opposite
forces of attraction and repulsion, and are spiral. While gaseous
nebulæ may be of any conceivable form, the direction and operation
of the forces which will determine their character as solar systems
must be similar, just as with the forms of organic life, and the only
nebulæ which reveal a distinct systematic development in harmony with
a working solar system are the spiral. There is no difficulty whatever
in tracing such a nebula through all its formative stages, as we have
done, and we can, in fact, see painted on the background of the sky
every step of the shifting tableau through which such forms must pass.
By the nebular hypothesis the whole course of development, of
necessity, is rigidly forward to its culmination; but by employing
the analogies presented to us in other operations of nature, we
can readily account for variations, haltings, ineffectual efforts,
uncompleted processes, and even reversals and redistributions into
other secondary sources of energy. They equally comprise the agencies
for the production of a single solar system or of a myriad, just as we
see the vortical water-spouts or sand-storms either single, double,
or multiple; they are flexible, as are all the processes of nature,
and require no violent assumption of a prior physical basis known to
us "ne'er before on sea or shore." They also account for the deviation
from the normal of the orbits of Neptune and Mercury, for the formation
of the asteroids and Saturn's rings, for the different eccentricities
and inclinations of the orbits, for the forward axial rotation of
the planets and their satellites, and even for their perturbations
and abnormalities; they furnish a basis for Bode's empirical law,
for the distribution of the planets in size, for the origin of comets
and meteor streams, for Kepler's laws, for the equal and permanent
relation of eccentricities and inclinations, and for the fixed axial
position of the moon with reference to the earth; they account for the
free oxygen in the planetary and free hydrogen in the solar atmosphere,
they employ the variation of volume of the sun as a regulator instead
of an independent generator of light and heat, and they are in entire
conformity with the established principles which govern the electrical
generation of active forces, their transmission to the sun, their
transformation into light and heat, and their return to the regions
of space, where they continue to act with potential energy to all
eternity, as they must do if space itself is eternal; and we surely
know that, if anything whatever is eternal, space must be so. This
great ocean--the home, the domain, the workshop of creative energy--is
the last retreat of the human intellect; here it may find rest, and
here alone. While solar systems may afford in their circling planets
a possible dominion for finite life, and in their suns their daily
bread; in the infinite and all-embracing realms of space, filled with
the potentialities of all created forms, thrilled with the impulses
of all creative force, is to be found the unfailing source of all,
the dominion of the eternal architect, before whom nature bends the
obedient knee, waits to hear his mighty voice, or swiftly runs to do
his royal bidding.