[_The first volcano_. l. 68. As the earth before the existence of 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 solar volcanos.] [_Her airless realms of frost_. l. 82. If the moon had no atmosphere at the time of its elevation from the earth; or if its atmosphere was afterwards stolen from it by the earth's attraction; the water on the moon would rise quickly into vapour; and the cold produced by a certain quantity of this evaporation would congeal the remainder of it. Hence it is not probable that the moon is at present inhabited, but as it seems to have suffered and to continue to suffer much by volcanos, a sufficient quantity of air may in process of time be generated to produce an atmosphere; which may prevent its heat from so easily escaping, and its water from so easily evaporating, and thence become fit for the production of vegetables and animals.