The Roanoke times. [volume] (Roanoke, Va.) 1890-1895, 1892-03-13
)CK PANTS COMPANY,
TAILS OF COMETS.
They Vary Not Only in SIze But in An
pearance az Woll.

=
pearance az Woll.
Tho tails OF comets are evidently
composed of finely divided matter
driven off from the bodies of the comets,
perhaps by the effects of evaporation or
of electrical repulsion, as they approach
the sun. From the kind of curve that
the tail describes differences have been
drawn as to the nature of the substances
which the comet contains.
Sometimes a comet has a long.
straight tail pointing directly away
from the sun, and almost at a right
angle to the path in which the comet
travels when it is near the sun. Such
tails are believed to be composed of
hydrogen which, on account of the
hghtness of its molecules, would be
driven off by the repulsive force with
great velocity.
Other comets have splendid sword
shaped or scinetar-shaped tails, bend
ing gradually backward on the side
away from the sun. 1t is inferred that
the particles composing such tails are
driven off with smaller relative
velocity, as would be the case if they
were the molecules of carbon combined
with hydrogen. Many combinations of
carbon and hydrogen are known to
chemists SO that the constitution of
such comets presents, in some respects,
likeness to things familiar to us upon
the earth.
Still other comets have short bushy
tails bending sharply backward from
the direction of the comets motion.
These tails, it is thought, may be COM
posed of the molecules of iron. Prob
ability is lent to this view by the fact
that meteorites are largely composed of
iron, and there is an undoubted connec-
ton between meteors and comets.
few years ago a comet appeared
whose tail presented such a peculiar
curvature that it seemed to be COM
posed OF particles heavier than the
molecules of iron, and it was suggested
that, in this case, gold was the element
concerned! A golden visitor from the
mysterious realms of space, shining for
short time in our skies while it paid
its respects to the sum-
Quite recently new line of inquiry
into the nature of comets has been
pointed out by Mr.. Barnard, of the Lick
observatory. He has called attention
to the fact that comets of short pc
riod-that Is those which travel in com
paratively short orbits, and appear
again and again in the neighborhood of
the sun after only few years absence
bear striking resemblance to one
another, and differ in appearance from
other comets.
They are large, round and diffuse be-
coming very gradually bright in the
middle but possessing no decided nu-
cleus, and they have no tails. Recently,
upon the appearance of previously
unknown comet which possessed these
peculiaritics he predicted that it would
prove to be a comet of short period, and
so it has turned out.
Comets are subjected to forces that
gradually scatter their substance as
they swing time after time around the
sun, and in this way they are eventually
changed into swarms of meteors. The
peculiar appearance noted by Mr. Bar
nard in short-period comets may simply
arise from the gradual disintegration of
those bodies, which, in the course of
ages, may disappear and never again be
seen by man, unless perchance a me-
teoric fragment that once formed part
of their substance should encounter
the earth, and fall upon it's surface.