The Douglas independent. [volume] (Roseburg, Or.) 187?-1885, 1879-09-27

Iscentihc Ameriean.i

IScentifc Ameriean.j
On the 10th Of August last the earth. Z
in its accustomed journey through space.
reached the outer edge of the supposed
meteoric ring which it annually passes
through at this period of the year. In
the vicinity of New York large num-
bers of meteors were seen during the
night of August 10th, some of them be-
ing OF comparatively large size, very
bright, and leaving long trails. Doctor
Lewis Swift, in q recent letter to the
Rochester Express, gives the following
information concerning these remarkable
heavenly bodies:
Meteoric astronomy now takes rank as
a distinctive branch of astronomical
science. Not forty yeyrs have elapsed
since it was ascertained that star showers
are periodical. Even then, and for many
years after, it was supposed there were
but two, called the August and Novem-
Der showers. Now, not less than oz1e
hundred have been detected, and others
are constantly being added to the list
The accounts OF the showers that occur
red IN ancient times came down to as
clothed in such extrayagant language
that, until the great star shower Of No
vember Ii, 1888, astronomers were 10th
to believe them. Now they know not
only the cause, but are able to predict
their recurrence with almost as myseh
exactness as eclipses, and the popular
mind observes these displays with equa-
nimity and delight instead Of fear and
alarm, or thinking the day of Judgment
has come. Science has disarmed not
only them, but eclipses and comets as
well, of their terrors.
All know what q shooting star looks
like, but no living man can tell MS what
it really is, for not one has ever been
known to reach the earth. Those heavy.
stony, and still more weighty metallic
masses, called meteorites, meteoric
stones, etc., which occasionally fall to
the earth from the celestial regions, Of
which the one that recently fell in Iowa
was a remarkable example, belong to
another class of objects entirely, Of the
origin of which man knows nothing.
A shooting star is only visible whlA :
undergoing the process of combustion,
which lasts from one to three seconds,
seldom longer. Previous to this they
exist in dark, probably solid condition.
not much, If any, larger than peas, too
small to be seen by daylight, and at
night, being in the earth's shadow, are
eclipsed and consequently invisible.
Only while being burned are they visi-
BILE to us, as then they shine by their own
light.
Each meteoroid moves in an orbit, re-
volving around the sun with as much
regularity as the larger planets. In fact,
each is in every sense of the word
planet, obeying strictly the laws Of gray
itation and planetary motion. All space
is filled with them; they are as numerous
as the sand The earth and they in their
journey around the sun encounter each
other; the earth, by its superior attran-
tion, draws them toward il, but TO reach
it they must pass through the atmos-
phere, which not one is able to do. Only
meteoric stones are able to reach the
earth, and they have their surfaces black
ened and converted to scoria by the ter
rible heat engendered by the friction
with the atmosphere and by arrested mo-
tion.
Shooting stars move in all directions,
and at velocities probably equal to the
earth's, nearly nineteen miles second.
One moving retrograde, therefore from
east to vest, would plunge into the at
mosphere at relative velocity Of s}SIls
thirty eight miles second Tand, II allow
ance be made for accelerated motion
| caused by the earth's attraction, proba-
bly, double that, or seventy five miles q
second. The encounter is fearful, and
but for the atmosphere which acts as q
cushion, the effect would be disastrous,
! for not less than 500, 600 900 would rain
upon the earth every day.
The source from whence these me-
teoroids come is comets, especially from
| their tails. The tail of the great comet
of 1911 was 150, 900, 900 miles IN length
and IL, 600, 900 in diameter Il is I'M
| probable in the highest degree that the
| comet could gather its tail to itself again.
| It is left behind, forming part of ring,
| which in time may become continuous.
| Another comet comes and it does the
same, and during the ages which are past
this process has been going on till the
| interplanetary spaces are filed with not
only meteoroids, but something still more
marvellous.
1 In about three thousand years that
great comet will return again and repeat
the process, forming part of another
ring, or adding TO the first, depending on
circumstances which need not be consld-
cred here. Whenever the earth, in its
annual journey. passes through any ring
made by some comet, no man knows
when, we get star shower. The four
most notable ones IN our times
take place at the following dates,
namely, on the mornings of August II
and November Il, and the evenings Of
November "a and "a. The last two are
caused by the earth passing through the
track of meteoroids left behind by the
fragments of Bida's comet, which di-
vided into two parts in 1876. In this
way meteoric rings are formed, OF which
the solar system is filed, but none are
visible to us, except those the earth
passes through. BY some such process.
was the August ring formed, which ths
earth passed diagonaliy through on ths
evening of the 10th and morning Of th.
18th Of the present month.
|. The first August shower mentioned II
history occurred on July %. A. d. 81
and has appeared with unfailing regular
ity down to our time, except break o.
eighty-three years between 8z1 and 924
and another and much longer one Q.
three hundred and ten years, between
933 and 1913, owing, probably, to breaks
In the ring, or, which is more likely, <
failure to record them. The period o.
the above comet is about one hundred
and twenty three years. and it viii there
fore make its next appearance about the
! year 1885.
The eccentricity Of the August ring
, is very great, its perihelion distance be.
!, ing equal 70 that Of the earth, and iti
aphelion distance far beyond the orbiI
Of Neptune, making the circumference
of the ring more than II, 600 ,D00, ,00(
| 49,, 1s.~- -.
ing through it, It's thickness must be 81
least 16 ,O00, 900 n1iles.
Il L Joke Returned.
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