350 
There is one line of thought which seems to lead to a settle- 
ment of this question. If the nebular hypothesis of the 
formation of solar systems be accepted as true, either wholly 
or partly, there can be no doubt as to the interspheral status 
of matter. The conditions of nebular aggregation indisputably 
settle it. 
This hypothesis holds that the matter now concentrated into 
suns and planets was once more widely disseminated, so that 
the substance of each sphere occupied a very considerable extent 
of space. It even declares that the matter of the solar system 
was a nebulous cloud, extending far beyond the present limits 
of that system. From this original condition the existing con- 
dition of the spheres has arisen, through a continued concentration 
of matter. But this concertration was constantly opposed by 
the heat energy of the particles, or, in other words, by their 
centrifugal momentum. This momentum could be only got rid 
of by a redistribution of motor energy. If, for illustration, the 
average momentum of the particles of the nebula was just 
equivalent to their gravitative energy, then a portion of this 
energy must radiate or be conducted outwards ere the internal 
particles could be held prisoners by gravitation, The loss of 
momentum inwardly must be correlated with an increase of 
momentum outwardly. 
This is a necessary consequence of the heat relations of matter. 
As substance condenses its capacity for heat decreases, and its 
temperature rises, hence a difference of temperature must con- 
stantly have arisen between the denser and the rarer portions of 
the nebulous mass, and equality of temperature could be restored 
only by heat radiation, This radiation still continues, and 
must continue until condensation ceases, and the temperatures of 
the spheres and space become equalised, but this is equivalent to 
declaring that as the particles of the spheres decrease in heat 
momentum those of interspheral space increase, and if originally 
the centrifuga] and centripetal energies of matter approached 
equality, they must become unequal, centripetal energy becoming 
in excess in spheral matter, centrifugal energy in the matter of 
space. Thus, asa portion of the originally widely distributed 
nebulous matter lost its heat, and became permanently fixed in 
place by gravitative attraction, another portion gained heat, 
became still more independent of gravity, and assumed a state | 
of greater nebulous diffusion than originally. The condensing 
spheres only denuded space of a portion of the matter which it 
formerly held, and left the remainder more thinly distributed 
than before. The spheres, in their concentration, have emitted, 
and are emitting, a vast energy of motion. This motor energy 
yet exists in space as a motion of the particles of matter, which 
therefore press upon each other, or seek to extend their limits, 
with increasing vigour, so that the elasticity of iinterspheral matter 
is constantly increasing. 
It might be hastily imagined that such an excess of heat vigour 
in the matter of space over that of the spheres should declare 
itself in temperature. But it must be remembered that temper- 
ature is no measure of the absolute heat contents of matter. 
Condensation increases, rarefaction decreases, temperature 
with no necessary change in absolute heat contents. The 
expression ‘‘ fire mist,” so often applied to the matter of uncon- 
densed nebulz, gives a very erroneous impression, The matter 
of the solar system nebula, though containing a high degree of 
absolute heat, was probably of low temperature. Its great 
rarity must certainly have greatly decreased its temperature. As 
a differentiation in this matter took place, one portion becoming 
condensed, another portion more rarefied, the former must have 
increased, the latter decreased, in temperature. Eventually the 
extreme condensation of one portion of this matter, and rare- 
faction of another, caused an extreme difference in temperature. 
An excessive radiation from the spheres to space has taken place 
in consequence, the absolute heat of the former constantly 
decreasing and that of the latter increasing. But the difference 
in temperature still continues great, the influence producing it 
acting much more rapidly than the influence tending to obliterate 
it. Eventually an equality of temperatures may be produced, 
but only by the production of a very considerable inequality of 
absolute heat, This must be the final result of spheral conden- 
sation and nebulous rarefaction of exterior matter; namely, 
equalization of temperature, with a change from the original 
homogeniety to a great hetercgeniety of heat contents. 
But we are again brought back to the question of the motor 
energies of matter. Are they sufficiently great to enable a 
portion of this matter, when reinforced in motor energy by 
radiations from the spheres, to defy gravitative attraction and, 
NALGORE 
feb, 8, 1883 7 
remain free in space? Undoubtedly so, and much greater than : 
would be simply requisite for the purpose, since we find the 
matter of the planets, after their immense losses by radiation, 
still possessed of a considerable excess of motor energy. The 
earth, for instance, has an orbital motion sufficient to maintain — 
it at a con-iderable distance from the sun, But the motion of 
the earth is but the combined motion of its molecules. This 
motion once existed as independei.t molecular motion, which in 
time, under the influence of gravity, became dependent mole- 
cular motion. We have already spoken of the fact that the 
particles of space, in consequence of their heat motions, tend to 
dart off in straight lines of motion, except in so far as the 
gravitative attraction of spheres causes these lines to become 
curved, These lines of motion, so far as individual particles 
are concerned, are checked by the particles coming into contact 
with others. The motion, however, proceeds onwards, though 
it is carried by successive, instead of by single particles. If, 
however, a number of particles move in company in the same 
direction, they may move much further as individuals, before 
transferring their energies. And if an immense mass of 
particles come to thus move in company their individual excur- 
sions may be indefinitely extended. The lines of motion, instead 
of being continued by successive particles, are continued by the 
same particles, and molecular motion becomes mass motion. 
The motion of terrestrial molecules, in their revolution around 
the sun, resemble those of the molecules in Prof. Brooks vacuum 
tubes, constituting his ‘‘ fourth state of matter.” 
Now the degree of resistance of such a mass to centripetal 
energy will indicate the degree of resistance of the original uncom- 
bined molecules. In the earth the motion of the molecules, thus 
combined, yields a centrifugal energy sufficient to maintain the 
earth at its present distance from the sun, But this is only a 
portion of its molecular energies. Its molecules possess 
considerable indep:ndent motion, and form nodes in lines of 
radiation that extend in every direction. They have also lost a 
great vigour of motion by radiition to space. It follows that the 
original momentum of these molecules must have constituted 
a centrifugal vigour greatly in excess of their centripetal vigour. 
It secondarily follows that the momentum of those molecules of 
the nebula which still exist in space, augmented as it has been by 
radiations from the spheres, yields a very energetic excess of centri- 
fugal vigour. Many of the comets have a centrifugal energy in 
excess of the centripetal energy of the sun, yet this represents only 
a fraction of the energy of their molecules, and a much smaller 
fraction of the energy of the material particles of space. 
The combination of the centrifugal energies of terrestrial 
particles is due to the fact of a secondary centre of gravity 
having heen formed. The heat velocity of its particles, in 
excess of that displayed in their revolution around the sun, has 
become partly a revolution around the earth’s axis, and is partly 
retained as heat vibration. But the heat velocity of the material 
particles of space is not thus secondarily employed. It is 
affected by the attraction of the sun, or of the nearest sphere ; 
but evidently, from the considerations above taken, this 
attraction cannot be sufficient to over-balance the centrifugal 
energy and cause atmospheric aggregation or even to cause 
orbital revolution, The particles must have energy suffi- 
cient to make them independent of spheral gravity. Their 
straight lines of motion must become to some degree curved in 
response to gravity, but cannot become closed curves. Instead 
of becoming planetary, they remain cometary lines, of very 
open orbit. For if we imagine the earth to be suddenly 
restored to its nebulous condition, or its particles to be set free 
in space, they would possess a ve ocity of motion much in excess 
of the earth’s orbital velocity. Hence they could not be con- 
trolled by the sun. The exi ting particles of space possess a 
stillmuch greater velocity, and are therefore much more free 
from gravitative control. 
Certain necessary results of this condition have been con- 
sidered. The lines of centrifugal motion in space are not con- 
fined to single particles as in the earth, but are transferred from 
particle to particle, The effect, however, is precisely the same ; 
this motion of successive particles is in no respect different in 
effect from what we would have if a single particle were free to 
move in the same direction. Each particle moves a certain 
distance, and then transfers its motion in that direction to 
another. But it immediately pursues some other direction of 
motion in response to impact, and this aids in the progressive 
moyement of innumerable lines of motor energy. The great 
centrifugal vigour of these motions must cause an energetic com- 
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