earthquakes was nearly level, and the greatest part of it covered with
sea; when the first great fires began deep in the internal parts of it,
those parts would become much expanded; this expansion would be
gradually extended, as the heat increased, through the whole terraqueous
globe of 7000 miles diameter; the crust would thence in many places open
into fissures, which by admitting the sea to flow in upon the fire,
would produce not only a quantity of steam beyond calculation by its
expansion, but would also by its decomposition produce inflammable air
and vital air in quantities beyond conception, sufficient to effect
those violent explosions, the vestiges of which all over the world
excite our admiration and our study; the difficulty of understanding how
subterraneous fires could exist without the presence of air has
disappeared since Dr. Priestley's discoveries of such great quantities
of pure air which constitute all the acids, and consequently exist in
all saline bodies, as sea-salt, nitre, lime-stone, and in all calciform
ores, as manganese, calamy, ochre, and other mineral substances. See an
ingenious treatise by Mr. Michel on earthquakes in the Philos. Trans.

In these first tremendous ignitions of the globe, as the continents were
heaved up, the vallies, which now hold the sea, were formed by the earth
subsiding into the cavities made by the rising mountains; as the steam,
which raised them condensed; which would thence not have any caverns of
great extent remain beneath them, as some philosophers have imagined.
The earthquakes of modern days are of very small extent indeed compared
to those of antient times, and are ingeniously compared by M. De Luc to
the operations of a mole-hill, where from a small cavity are raised from
time to time small quantities of lava or pumice stone. Monthly Review,
June, 1790.]

[_The moon's refulgent car_. l. 79. See additional notes, No. XV. on