The New Orleans bulletin. [volume] (New Orleans [La.]) 1874-1876, 1874-07-19
ANCIENT THEORY OF COMETS.
THE NEWTONIAN THEORY THEORIES.

Among the ancents, comets were supposed
to be 50 many heaps or masses OF dimlnu-
tive stars According to Aristotle, they were
only "a kind Of transient fires or meteors,
region of the air, and then set on fire" Some
believed them to be perpetual stars moving
in their proper orbits, and made visible at
times when left by the sun, so as to display
their own radiance, no longer lost in the
exceeding radiance of the sun Seneca
argued against their being meteors, and said ;
II take a comet to be sudden fire,
but esteem it among the eternal works
Of nature" Apolonius Myndius took
comets for regular stars" affirming
also, that among the Chaldeans they were
reckoned among the planets, and to have their
own periods like the planets. He also ven
tured to foretell that some day the laws and
period, of their motions would be deter
mined-a prediction which has been verified
| by Newton.
The theory of Aristotle, that they were
meteors, long prevailed, till Tycho Brahe,
diligently observing the comet of 1877, and
finding it had no sensible diurnal paradox,
assigned it to its true place in the planetary
| regions.
Although few comets have appeared so near
| the earth as to show diurnaI parallex, they
| afford sufficient indications of an annual
| parallax that is, the revolution Of the earth
-, H., 20,
be very different from what it would be if
they were viewed from the sun, or any fixed
| place. This shows they are not so distant as
the fixed stars, which have no annual paral-
lax; and, as Hevelius observes, affords proof
| of the earth'S revolution round the sun; for,
without surprising that, these motions Of
comets are inexplicable. Kepler supposed
their lines were nearly rectilinear and Hell
| vetius that they moved in parabolic trojec-
tories, in the same manner that projectile
from the earth's surface describes parabola.
Sir Isaac Newton showed that the comet of
1880 would have been dissipated in the neigh
borhood Of the sun and planets Of which
Hevehus imagined they were composed Ac-
cording to Newton, it would seem that il is
the rarefaction of the immense nucleus of
atmosphere surrounding comet, as dissipated
by the heat Of the sun which forms its TAIL
frightening into space as comet approaches
the sun, and necessarily expanded and curved
as heightened in keeping with the motion of
the comet round the sun. The vapors of
comets thus dilated, rarefied and diffused
through the celestial regions may, by means
Of their own gravity, be attracted to the planets
and intermingle with their atmospheres, for
conservation of resupplying moisture, SO neces-
sary to life and vegetation to such planets as
may have had their own moisture too much
exhausted by their heating processes.
Another use which Newton conjectu es
comets may be designed to serve, is that of
recruiting the sun with fresh fuel and repair
ing the consumption Of his light by the
streams continually sent forth in every direc-
ton from that luminary
DR.. Hamilton argues against the Newtonian
theory that We have no proof Of the existence
Of solar atmosphere, and if we had, the
tails be ng of lighter specific gravity than the
comets themselves, would be struck of from
them and left behind, and would not appear |
opposite to the sun, and afterwards should |
appear towards the sun. He concludes that |
the il Of comet is formed of matter which |
has not the power Of refrac ing or rejecting
the rays of light-the electric matter in vucuo
Of the atmosphere suffering the rays of light |
10 pass through without being affected BY
them like an aurora borealis.