9 | Direct | |
|Blaupain | 1819 | | 2 | Direct | |
|Lexell | 1770 | | 1 | Direct | |
|--------------------------------------------------------------------|
|Pous | 1812 | | 17 | Direct | |
|Olbers | 1816 | about | 40 | Direct | Saturn |
|De Vico | 1846 | 75 | 13 | Direct | and |
|Brorsen | 1847 | years. | 12 | Direct | Uranus. |
|Westphal | 1852 | | 21 | Direct | |
|Halley | 1682 | | 16 | Retrograde| |
+--------------------------------------------------------------------+

From which it appears, that the objection arising from the great
inclination of the _planes_ of these orbits is much less important than
at first it appears to be.

Regarding then, that a comet's mean distance depends on its mean atomic
density, as in the case of the planets, the undue enlargement of their
orbits by planetary perturbations is inadmissible. In 1770 Messier
discovered a comet which approached nearer the earth than any comet
known, and it was found to move in a small ellipse with a period of five
and a half years; but although repeatedly sought for, it was the
opinion of many, that it has never been since seen. The cause of this
seeming anomaly is found by astronomers in the disturbing power of
Jupiter,--near which planet the comet must have passed in 1779, but the
comet was not seen in 1776 before it passed near Jupiter, although a
very close search was kept up about this time. Now there are two
suppositions in reference to this body: the comet either moved in a
larger orbit previous to 1767, and was then caused by Jupiter to
diminish its velocity sufficiently to give it a period of five and a
half years, and that after perihelion it recovered a portion of its
velocity in endeavoring to get back into its natural orbit; or if moving
in the natural orbit in 1770, and by passing near Jupiter in 1779 this
orbit was deranged, the comet will ultimately return to that mean
distance although not necessarily having elements even approximating
those of 1770. In 1844, September 15th, the author discovered a comet in
the constellation Cetus, (the same previously discovered by De Vico at
Home,) and from positions _estimated with the naked eye_ approximately
determi