m remains unimpeached.

VIII.

_If they rise to the Hill-tops._ } Rain in a Day or two.

WHEN Mists are very, heavy in themselves, and rise only by the Action
of that protrusive Force, exerted by the subterranean Fire, they can
rise no higher than where the Gravitation becomes superior to that
protrusive force, for then they descend again by their own Weight, and
this occasions the Appearance mentioned in the Observation of their
hanging upon Hill-tops, where they are very soon condensed, and fall
down in Rain.

THERE was formerly a very idle and ill grounded Distinction between
moist and dry Exhalations, whereas in Truth all Exhalations are moist,
or in other Words are watery Steams thrown off by Bodies respectively
dry, and the former Distinction was invented only to solve these
Phaenomena of which we have been speaking, that is, the Mist rising and,
dispersing without Rain, and the Mist condensed and resolved into Rain,
which as I have shewn may be much better explained without any such
Distinction.

IX.

_A general Mist before the Sun }
rises, near the full Moon._ } Fair Weather.

THIS is a general and a very extensive Observation, which enables us to
judge of the Weather for about a Fortnight, and there is very great
Reason to believe that it will very rarely deceive us. In order to
convince the Reader of this, it will be necessary to explain, as far as
we are able, the Causes of this.

MISTS are observed to happen when the Mercury in a Barometer is either
very low of very high. They happen when it is high after the Region of
the Air has continued calm a good while, and in the mean time a great
Abundance of Vapours and Exhalations have been accumulated, making the
Air dark by their quantity, and the disorderly Disposition of their
parts. They happen when the Mercury is low, sometimes because the
Rarity of the Air renders it unable to sustain the Vapours, which
therefore descend and fall through it.

BUT none of these Cases agree with the Observation at the Head of the
Page, and therefore to form a true judgment of the Weather, we must
distinguish between them and the Case which explains the Observation.

X.

_If in the new Moon._----Rain in the old.

WHEN Exhalations rise copiously from the Earth into the Region of the
Air, and the Air itself is in a proper Disposition, they ascend to a
great Height, and continue a long Time before they are condensed, which
accounts very clearly and philos