St. Landry democrat., 1882-03-04

the educated, and the superstltlOus terrois VI
the ignorant. The matter of which III Is com-
posed must be expanded to an almost lncon.
ceivabIe degree for even when it is millions ol
miles in diameter the light of the faintest stars
is seen through it with scarcely dlnlilsheo
brightness.
THE BLACK STREAK IN THE TAIL.
Near the head, it often appears to consist OF
two streams of matter issuing from either sue
of the coma with a dark channel OF separation
between. The tail at this point generally ap
pears to have the same diameter. from "ndI-
ever direction in space it is viewed. we must,
therefore, conclude that it's interior Is nearly
or quite free from matter. and like hoiloM
cylinder or portion Of cone, as far as the dafk
channel extends. Beyond that point we may
suppose that the interior fills up by gradual
diffusion from the circumference In some ,i
cases, and especially with small comets, tne
dark channel is wholly wanting, or but family
Indicated
CURVED DIRECTION OF THE TAIL.
In order to give an idea of the sitnaton OF
the tail i'll space, let us imagine line from the
sun continually prolonged through the moIlng SInii
head of a comet into space beyond. we snail
always find the tail extending nearly opposite
the snn, in the direction of this proiongatlon,
but curved more or less backward from IT,, III
the direction from which the comet is moving.
Sometimes we find mOre than one tali-eacn
distinguished by the degree of it's backward
inclination. They have, indeed, been CLASSIFIED
on this ground and found cOnformabe to three
general types.
ORIGIN OF COMETS.
5 4. The facts thus far presented prove moth
ing as to the origin of comets. That question
demands for its solution mathematical reason
ing based on the calculated paths of all comets
which have been observed. That discussion Is
beset with great difficulties, and as yet points
to no absolutely certain conclusion. The bal
ance OF testimony seems to favor the supposl-
ton, that comets originate outside the solar
system. The planets move in nearly circular
orbits about the sun; and no one has been able
to show why comets, if they have the same
origin, should move in elongated orbits, entlre-
ly differing from those OF planets.
Let us suppose, however, that all comets
must have taken their origin in some primeval
nebula from which a solar system has been
evolved It has been shown that the velocity
of acOmet may be so much increased by the
disturbing action of a large planet, that it may
escape from the control OF the sun, and be pro
jectedf into the illimitable regions OF space.
Thus freed, it will go on in nearly straight
line forever; unless, percbance, some powerful
source OF attraction, like another sun, lying
near its path arrests its flight. The possibility
of such an occurrence is by no means imagina-
ry. At least one comet [Lexell's, l770l is sup
posed with good reason to have undergone that
fate. There is every reason to believe that the
same thing may have happened in other cases.
STELLAR COMETS.
All argument drawn from observation and
reflection prove that the stars which surround
us On all sides are remarkably like Ollr own
sun. Some of them are even larger and more
powerful than he. Reasoning from analogy,
we must suppose that these suns are also at
tended by comets. Hence. we are led to the
conclusion that uncOunted myrlads OF comets
projected forth from millions of suns. during
counties ages past, are now flying through space
in every direction-restless messengers from
star to star. By mere chance some OF these
bodies must come under the suns far-reaching
power and be drawn into our planetary sys-
tenn.
PHYSICAL HISTORY OF COMETS.
s 5. The mass Iquantity of matter] Of comets
is conceded to be very small in comparison
II ,f fhn pth Sula ia yV6
cannot say. No comet has been found large
enough to exert a sensible attraction upon any
celestial body found in its vicinity. This fact
confirms the conclusion derived from telescope
examination. that the real, solid nucleus, If it
exists, must be extremely small.
1t is certain that no body entirely gaseous
could exist in space. The conditions for the
stability of liquid bodies i'll their practical ap-
plication to the explanation of cometary pine
nomena, are extremely complicated; since they
are closely associated with the unknown eie,
ments-mass of the comet, solar radiation, and
absolute temperature OF space. 1t would also be
extremely difficult to show how swarm OF
small bodies could be presel we'd in state OF
equilibrium or reisst the tremendous tidal ac
ton to which it would be subjected in the vi
cinity OF the sun. In fact we must view the
convention of a comet through some unusual
catastrophe, into such a swarm, as the sure
precursor of approaching dissolution. On the
whole, it is probable that there IS solid or
partly liquid body near the center OF the COM
ct. This body is more likely to consist OF an
aggregation Of loosely cohering pieces or par
ticfes than of a single firmly united mass
Owing to the slnallness of their attractive
force, comets cannot retain sensible atmos-
phefe. This conclusion is confirmed by teles-
copic Observatian as we have seen.
IT, now, we suppose the nucleus to be ap-
preaching the sun, it will eventually reach
point where the liquid or other volatile matter
on the sunny side commences to eyaporate
and be diffused about the comet. Without fol
lowing the consequences OF this evaporation
into details one can imagine for himself how
| ba condemnation,
the streaming jets, and Of the nucleus heavily
obscured by Vapors, might be produced.
To account for the backward curvature OF
the jets and the peculiar form and direction OF
the tail, we must look for some additional force.
In all probability this force resides in the sun,
and is directly opposite in its effects to the
power of gravitation. But since the body OF
the comet obeys the laws OF gravitation with
sufficient fidelity, we must find repulsion
which senslbly acts only on the molecules of
gas or vapOr.
The only force suggested by experience as
competent to these requirements is that OF
strict electrical repulsiOn, Anyone can prove
for himself that two bodies similarly electrified
mutually repel each other. We know that the
earth through effects of constant evaporation
and other causes, is to some extent an electri-
fed body. For the same reasons, we should
expect comets to be electrified in much high
er degree The sun itself certainly eterts an
influence upon terrestrial magnetism Violent
commotions on his surface have occurred at
the same time with unusual disturbances OF
in proportion to surfaces and not to volumes.
On particles of matter in state OF infinitesmal
subdivision it might act most powerfully, while
not affecting large body to an appreciable
degree.
THEORY OF FORMATION OF TAILS.
If, then, we suppose the sun and comets to be
sufficiently and similarly electrified, we have
the force necessary to produce the backward
curvature of the Jets, and to drive off the
smallest and probably outermost molecules OF
the coma to form the tail. Since. according to
our hypothesis, very little matter can be given
off from the shaded side of the nucleus, we
readily perceive why the tail should be hollow
in appearance.
curved, it is evident that the parties driven of
at any time with less than infinite velocity.
would continually fall more and more behind
tha nrnlnn cation OF line through the sun and