The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1879-08-11
Metstoric showers.

AS the time for the annual star-shower OF
August 10th Is at hand, Professor Lewis
Swift, the Rochester astronomer, has con-
!fributed to the Euenin9 Express OF that city
an interesting article on the subject.
Though the facts which he gives are well
known to astronomers, much OF the matter
will be new to the general reader. For ln-
stance, the difference between shooting-stars
and meteoric stones is little understood BY
those who have not made study OF astron-
.omy. The meteorites move in orbits, re-
volvlng round. the sun with as much regu-
Ierity as the larger planets. In fact, each Is
in every sense OF the word planet, obey
ing strictly the laws OF gravitation and
planetary motion. All space is filled with
them; they are as numerous as the sand.
The earth and they In their Journey round
the sun encounter each other. The earth,
by its superior attraction, draws them to-
ward it; but TO reach it they must pass
through the atmosphere, which not one is
able TO do. Only meteoric stones are able
to reach the earth, and they have their sur
faces blackened and converted to scoria by
the terrible heat engendered by the fric-
tion with the atmosphere and by arrested
motion. -..'. '.'' .
Shooting-stars, on the contrary, move in
all directions, and~at veIocities probably
equal to the earth's-ncarIy nineteen miles
second. One moving retrograde. there
fore urom east to west }, would plunge into
the atmosphere alta relative velocity OF some
tbirty-eig BIT miles second, and IL allowance
be made for accelerated motion caused by
the earh's attraction. probably double that,
or seventy-iye mllesa second. The cncoun-
ter is fearful, and but for the atmosphere,
which acts as cushion, the effect would be
dis ,strous-not less than 100000, 900 would
rain upon the earth every day. A shoot
iug-star is only visible while undergoing
the pEacess of combustion, which lasts from
one TO three seconds-Sedom longer. Pre-
vious 70 this they exist in dark, probably
solid, condition, not much, il any, larger
than pcas-too small 10 be seen by daylight,
and inthc night, being in the earth's shadow,
are eelipsed. and consequently invisible.
Only while being burned are they visible to
US, as then they shine by their own light.
The source from whence the meteorods
come is comets, especially from their tails.
The tail OF the great comet Of 1911 was
15O. .0OO, 900 miles in length and 100000 in
diameter. 1t is improbable in the highest
degree that the comet gathered its tail to IT.
self again. 1t is left behind, forming part OF
a ring, which in time may become contlnu-
Gus. Another comet comes and it does the
same, aud during the ages which are passed
this process has been going on till tue inter-
planetary spaces arc filed with not only
metcoroids, but something still more mar
Yeilous.
Whenever the earth in its annual Jour-
ney passes through any ring made by some
comet we get a star shower. The four most
notable ones in our times take place at the
following dates-viZ., on the mornings OF
August / and November Il and the eve
nings Of November "a and 27. The last two
are caused by the earth passing through
the track OF meteoroids left behind By
the fragments Of Bida's comet, which d.
vided into two parts in 1916. In this way
mcteoric rings arc formed, OF which the
solar system is filled, but none are visible
to Us except those the earth passes through.
By some such process was the August ring
| formed, which the earth will pass diagonally
through on the evening o; the 10th and
morning Of the 11th of the present month
The comet which produced it was discov'
cred by Professor Swift on the 10Th OF July
| 1900