The Sun.
London, England, 1861-07-11 00:00:00

THE COMET.

In Monday's sitting of the French Academy of
Sciences, M. Leverrier expressed himself as fol-
lows .—" We do not know this comet ; it is the
first time it visits us, and those who have endea-
voured to predict its course, determine its distance
from the earth, and measure its tail, have either
deceived themselves or the public. Three elements
are necessary to calculate the orbit of a comet ;
first, the exact position of the star ; then, its
velocity ; and lastly, the variation of velocity
produced by the mass of the sun. I caused the
comet to be observed on the 30th of June, and
then on the night of the Ist, and the morning of
the 2d inst., in order to determine the variation
of velocity. These three observations would have
followed too closely upon each other for the cal-
culation to be attempted, were it not that the
comet moves very rapidly. On the 3d, at 10 a.m.
M. Levy brought me the result of his calculations,
and we then obtained an insight into the orbit of
the comet. Mr. Hind has since sent me the orbit
calculated by the English astronomers, which per-
fectly agrees, in all but two minutes, with our re-
sults. It is now positive that this is not Charles
the Fifth's comet ; and, moreover, it resembles
none of those already observed. This circum-
stance will contribute not a little to throw con-
fusion upon the little we know of these erratic
bodies. I cannot yet say whether this comet is
periodical or not ; its orbit up to this day
has been too cursorily determined to enable us
to pronounce it elliptical, parabolical, or even
hyperbolical. At any rate appearances are
against its return, for the orbit is nearly perpen-
dicular to the plane of the ecliptic, while those
of periodical comets usually form a very small
angle with that plane. It is only now we can de-
termine the distance of the comet from-the earth,
and the length of its tail. On the 30th of June,
the line joining the centre of the sun with that of
the comet made an angle of four degrees with
that joining the centres of the sun and earth, the
length of which is known. The angle which this
line formed with the visual ray, drawn from the
eye of the observer to the centre of the comet,
was 24 degrees. The triangle thus formed may,
therefore, be calculated, and it gives us the
distance of the comet from the earth, amounting
to between six and seven millions of
leagues (about seventeen millions of miles
English). The length of Ithe tail might
be similarly calculated. The comet is rapidly
moving away from us, and it is, therefore, not sur-
prising that its brilliancy has diminished. On the
10th it will be equally distant from the sun and
earth ; we shall soon lose sight of it, and astrono-
mers only will be able to follow it for about a month
longer. It presents a singular peculiarity. M.
Chacornac has studied the nucleus with one of M.
Foucault's telescopes of a diameter of 40 centimetres;

instead of its being hollow like the half of an egg-
shell, like most of the comets already observed, it
presents the appearance of a sun composed of fire-
works, the bent rays of which burn in the same
sense. Moreover, the comet has not drawn nearer
to the sun. These are all circumstances calculated
to introduce great complications into the theory of
comets."