The weekly pioneer and Democrat. [volume] (Saint Paul, Minn. Territory) 1855-1865, 1858-10-14

PROF. xrTcHELL's OBSERVATIONS.

PROF. MfTcHELL's OBSERVATIONS.
.. N. Mitchell OF the Cincinnati Obsrya-
tory, communicates TO the Daily Gazette, q
very interesting paper regarding the Comet
which now makes 20 fine a display 10 our
western heavens at night. 1t was discov.
cred by Professor Donati, OF Florence, Italy,
nearly four months ago, and for q large por-
ton Of the time since it was detected has
been steadily approaching the earth, and in
o direction so nearly cOincident with the
visual ray, that but for the computations of
astronomers, might well excite anticipations
Of some fearful collision with our planet.
Indeed, throughout the present month it
seems TO have been plunging downward so
exactly toward the earth, that it scarcely
changed it's apparent place among the fixed
stars by quantity larger than two or three
times the diameter OF the moon.
II will reach its nearest approach 10 the
sun in few days. Its briIliancy will in
crease rapidly up to the close Of the first
week in October, when it will put on its
most splendid appearance, and will then rival
in grandeur the famous comet of HALEY, at
its last return 10 1886.
This comet, Professor Mitchell says, will
soon commence TO change direction, at first
slowly, afterwards more rapidly, as seen from
the earth, when sweeping swiftly round the
sun it will regain those distant regions of
space wherein vast proportion Of its orbit
lies far beyond the reach Of telescope vision"
He further states
"On the evening Of the 18th Of September
the appearance Of the comet, in the great
refractOr Of the Cincinnati Observatory, was
especially interesting. The central portion,
or nucleus, was examined with powers vary
ing from one hundred to five hundred, with.
out presenting any evidence of weldefned
planetary disc. II was brilliant glow of
light, dartng and flashing forward in the
direction Of the motion toward the sun, and
leaving the region behind in comparative
obscurty. But the most wonderful physical
feature presented was portion of nearly
circular nebulous ring, with its vertex d.
rected toward the sun, the bright nucleus
being 10 the centre, while the imperfect ring
swept more than half round the luminous
centre. This nebulous ring resembled those
which sometimes escape from steam pipe,
but did not exhibit the appearance which
ought to be presented by hollow hemi-
spherical envelope Of nebulous matter.
There was an evident concentration Of
light in the central portions Of the ring,
while, in the case of hollow envelope, the
brightest portion should be at the outer
edge. BY micrometical measurement, the
distance from the central point to the cir.
cumterence Of the ring was found TO be about
nine thousand miles. This would give u
diameter of eighteen thousand miles, in case
the ring was entire. Similar measurements,
made on the evening of the Goth Of Septem-
Der, indicated decided increase in the ra-
dius of the ring, which was now not less than
twelve thousand miles in length. On the
same evening ! noticed the fact that the ID
minous envelope did not blend itself into the
head portion Of the tail, but appeared some
what to penetrate into this nebulous mass,
especially on the upper part, presenting the
appearance of about 200 degrees of spiral.
The tail on the 25th was decidedly brighter
and better defined on the upper than on the
lower portion, while on the evening Of the
Goth there was much nearer approach to
equality in brightness. especially near the
head OF the comet. Through the telescope,
and near the head, the tail presented the APP
pearance Of hollow nebuous envelope, UNI
der the form Of parabaloid Of revolution,
the edges being brightest and well defined
while there was manifest fading away OF
light toward the central region. Through
the vast depth Of nebulous matter composing
this wonderful appendage, the iaintest teles
! copic stars shonc with undminished bright
ness.
NO one can gaze on this gigantic object
in all its misty splendor, without, deep I'M
preston that the eye is resting on a mass Of
nebuloas matter precisely such as the nebu
lous theory Of La Place supposes to have
been the primordial condition OF our sun and
/ all its attendant planets, and from which
/ chaotic condition this beautiful system of re
vol ing worlds has been evoked by the actor
OF a single law.
The only comet which has presented al
appearance resembling the one now visible
is the one known as Haleys Comet, as seer
by Sir William IIerschel and others in it
return in 1886 There is marked differ
encc between the two That while the en-
velope OF Halley's Comet is described as I
hemispherical hollow envelope, this show
more the shape of nebulous ring there i
a faint, misty light OF irregular outline, bu
not to b. mistaken by even a casual obser
yer.