St. Landry democrat., 1882-03-04

tiple tails which have been seen rs we'll as the
classification already described. Elaborate ex-
amlnations OF their average observed direction
and form suggest that each class may be com
posed OF chemical elements peculiar to itself.
We may even venture to suppose that the tail
Of greatest velocity and least inclination is
composed OF hydrogen. The second type may
contain carbon, with or without other ele-
ments; and among those of the third, chlorine
would most likely be found.
1t is common error to suppose that this hy-
pOthesis, as to the formation of the tail, re-
qures a repulsiye force of inconceivable power.
The straightest tails which have been observed
are accounted for by supposing a repulsive
force not much greater than twelve times the
suns attractive power. The tails most fire.
quently seen lscimeter-like in fOrm] may be
produced by a force about one-ninth of that
amount, which is but little mere than sufficient
to overcome the attraction of gravitatlon.
1t will be seen that it is equally erroneous to
suppose any great amount OF material is wasted
in the formation of the tail, when one reflects
upon the transcendent lightness of its struct-
ur6.
HOW COMETS AFFECT THE EARTH.
IS. The influence of comets upon the earth
is in all probability quite insignificant. They
may, like the sun, affect the earths magnetic
condition, and thus To some extent, possibly,
its metereology. No such effect has ever been
perceived. In spite of some chance coincl-
dences between the apparitiOns OF great comets
and remarkable public events. no well Uniformed
person now believes that there is any real
connection between them. By a liberal and
creduOuS Interpretation OF any frequently Oc-
curing celestial phenomenon, similar coinci-
dences could be shown.
When a comet is converted into meteoric bod
les, which impinge upon the earths atmos-
phere there is some direct though prop
ably minute effect Some have thought that a
sensible portion OF the heat which the earth re-
ceives Is generated in this way; but the weight
of scientific opinion seems to be against that hy
pothesis The impact of meteors upon our at
mosphere must add some matter to it, and this
is probably in the form of dust This may be
the origin OF the sO-called cosmetic dust, which
has been collected at sea i'll recent times. The
finer particles of 1t may have some influence on
cloud formations and other meteorological
phenomena; but all this is merely conjecture
A more remote effect may be sought in the
possible fall of meteors aud comets upon the
surface of the sun. Owing to his vast bulk. the
sun would attract an immense number OF these
bodies; but it is quite certain that their effect
upon the suns heat is insignificant. 1t is now
generally admitted that we must look for the
origin of the suns heat in a constant, though TO
us, imperceptible shrinking of his vast bulk.
Some connection between the frequency of
sun-spots and comets has been rather vaguely
suspected. Were the search for comets system
atically pursued with equal persistence for long
period, we might have some data for the for
nation of sound opinion. Yet it would still
he an omen question. whether comets cause the
spots or whether greater activity or the sun
tends in some way to render comets brighter,
so that more will be yisihle-with probability
in favor of the latter supposition:
Finally, it may be said, with all due respect
to scientific decorum that the appearance OF a.
great comet does exert one most happy lnf1u-
enee on the earth, in that it stimulates the GU
riosity of mankind, and diSects their thoughts
to the more particular contemplation Of the
glorious universe which surrounds them.