Ashtabula weekly telegraph. [volume] (Ashtabula, Ohio) 1853-1873, 1869-06-19
ASHTABULA OHIO, SATURDAY, JUNE 10 1869
Theories Of the Aurora Borealis,


frequently seen near the horizon, bearing
some resemblance TO the morning tyi.
light, wbeEce IL has received the maine of
Auroea. In the northern hemisphere il
is usually termed "Aurora Borcalis." be-
cause it is chiefly seen in the north. A
similar phenomenon is also seen in the
southern hemisphere, where il is called
"Aurora Australis." Ecch of them NAV.
with greater propriety, lie called "Au.
rora Polaris," or Polar Light. They ex-
exhibit an endless variety of appearance.
In the United States an aurora is mi.
formly preceded by a hazy or slaty ap
pearance Of the sky, particularly in the
ncighborhood of the northern horizon.
When the auroral display commences.
this hazy portion Of the sky assumes the
form Of dark bank or segment of n cir.
Gle in the north, rising ordinarily to the
height OF from five to ten degrees. This
dark segment is not cloud, for the stars
are seen through it as through a smoky
atmosphere, with little diminution Of
brilliancy. This dark bank is sinplv a
dense haze, and it appears darker from
the contrast with the luminous arc which
rests upon it. In high northern latitudcs,
when the aurora covers the entire beay.
ems, the whole sky seems filed with a
dense haze; and in still higher latitudes.
where the aurora is sometimes seen in
the south, this daIk segment is observed
resting ON the southern horizon and bor-
dered by the auroral light.
Auroras are sometimes observed stimuli.
taneouSly over large portions of the
globe. The aurora of August 2s. 1859.
was seen throughout more than I4O de.
grees OF longitude, from Eastern Europe
to California; and frcm Jamaica on the
south to an unknown distance in British
America on the north. The aurora of
September 2, 1859, was seen at the Sand
wich Islands; 1t was seen throughout
the whole of North America and Enropc !.
and the disturbance of the magnetic nee
die indicated its presence throughout all
northern Asia, although the sky was over
cast SO that at many places it could not
he seen. An aurora was seen at the
same time i'll South America and New
Holland. The auroras Of September 25.
l84l, and November, lS4S, were almost
equally extensive.
The height of large number of au-
roras has been computed, and the aver
age result for the upper limit of the
streamers is 450 miles. From a multi
tude of observations it is concluded that
the aurora seldom appears at an elevation
less than about 40 miles above the earth's
surface, and it frequently extends upward
TO an elevation of 500 miles. Auroral
arches having well-defned border are
generally less than 100 miles in height.
Auroras are very unequally distributed
over the earth's surface. They occur
most frequently in the higher ATTITUDES,
and are almost unknown within the trop.
les. At Havana, in latitude 23 degrees.
but six auroras have been recorded with
in hundred years, and south of Havana
auroras are still more untrequent. AS
we travel northward from Cuba, auroras
increase in frequency and brilliancy they
rise higher i'll the heavens, and oitenrr
ascend to the zenith. Near the parallel
OF 40 degrees we find Oh an average only
ten auroras annually. Near the parallel
of AZ degrees the average number is
twenty annually; near 45 degrees the
number is forty; and near the parallel of
90 degrees it amounts to eighty annu-
ally. Between this point and the paral-
lei OF W degrees anroras, during the
winter, are seen almost every night.
They appear high in the heavens, and as
often to the south as the north In re-
glons further north they are seldom seen
except In the south, and from this point
they diminish i'll frequency and briliancy
as we advance toward the pole. Beyond
latitude so degrees the average number
OF auroras Is reduced to forty annually.
Beyond latitude 81 degrees it is reduced
twenty and near latitude IS degrees it
is reduced to ten annually.
Auroral exhibitions take place in the
upper regions of the atmosphere, since
they partake of the ear ;h's rotation. All
the celestial bodies have an apparent
motion from east to west, arising from
the rotation of the earth but bodies
belonging to the earth, including the at
mosphere and the clouds which float in
it, partake of the earth's rotation, so
that their relative position is not affect
ed by it. The same is true of auroral
exhibitions. Whenever the auroral cor
va" 10 "''hSo, IL IHtintalllS SellSlOlE Jne
same position in the heavens during the
whole period ofits continuance; although
the stars meanwhile revolve at the rate
of Is degrees per hour
The gIosser part of the earth's atmos-
phere is limited to moderate distance
from the earth. AT the height of little
over four miles, the density of the air is
only one half what it is at the earth's
surface. At the height of fifty miles
the atmosphere is well-nigh inapprcci-
able IN It's effect upon twilight. The
phenomena of lunar eclipses indicated
an apprediable atmosphere at the height
of sixty-slx miles. The phenomena of
shooting stars indicate an atmosphere at
the height of 200 or 800 miles, while the
aurora Indicates that the atmosphere
does not entirely cease at the height of
500 miles. Auroral exhibitions take
place, therefore, in an atmosphere of ex-
treme rarity SO rare, indeed, that if, in
experiments with an air-DuInD we cOuld