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
that the probability of a contact is less, in an almost infinite degree,
than the proximity of a comet, which, notwithstanding, is an event which
every astronomer is fully aware, is within the verge of possibility.

The effects of a contact would be greatly modified by circumstance. Should
the comet strike the earth obliquely, it would glance off, and the
consequences would be partial. If the point of collision were on a
continent of the globe, mountains would be hurled from their bases, and
new ones would elevate their ridges towards the clouds. Were the place of
meeting on either of the great oceans, some regions would be deserted, and
others would be inundated by the waters of the sea. These dreadful
consequences would be increased, in an indefinite proportion, if the point
of contact were in the direction of the earth's centre; the meeting would
be terrific; the earth's period of revolution would, in all probability,
be altered, either by carrying it nearer to or farther from the sun; a
different inclination of the axis might be given, and there would be a
consequent change of seasons; the diurnal motion might be either
accelerated or retarded, by which the length of the day would be affected;
the vast continents of the globe would be again covered with the ocean,
which, deserting its bed, would rush towards the new equator.

Infinitely more tremendous would be the catastrophe if the earth were
struck by a _retrograde comet_ in the direction of th