It has been stated that the comet of 1770, passed through the system of
the planet Jupiter, without in the slightest degree affecting the motions
of either the primary or his satellites; also, that it passed sufficiently
near our planet to have shortened the length of the year had its mass been
equal to that of the earth. No effect whatever was produced, from whence
it may be concluded, that the neighbourhood of a comet is not of
sufficient importance to excite any alarming apprehensions for the safety
of the habitation of man.

Most of the calculations that have been made respecting the effect of the
proximity of a comet to our earth have proceeded on erroneous
principles,--over-rating the quantity of matter in comets, and losing
sight of their great velocity when in this part of the system. For a comet
to produce any direful effect, it ought to contain not merely a
considerable quantity of matter, but also ought to be vertical and
stationary to the earth's surface for several hours; instead of which, we
have sufficient reason to believe that though vast in volume, comets
contain but little matter in proportion, consequently, their attractive
energy would be inconsiderable; also their velocity would, in a very short
period, carry them beyond the limit of exerting any influence on the
waters of the globe. Of course, this general statement would be modified
by the rate and direction of a comet's motion, and also the earth's
rotation.

It may, then, be asserted with safety that the close appulse of a comet
would not be attended with any fatal results; and that this security
principally consists in its great velocity, which would so swiftly remove
it to a distance. But, the very circumstance which, in the case of
_proximity_, would be the security of our globe, (its velocity,) would, in
the event of a _contact_, be attended with the direst effects. It is true