It may be further assumed, that deep within the planet the elements abound in neither kind nor quantity as at the surface and in the atmosphere; and if the imponderable oxygen element be absent, an immense mass of ice would form the nucleus of the earth, the occasional melting at the surface of which, in the neighbourhood of sulphurous and ferruginous masses, may cause those volcanic eruptions from which no region of the earth is free. Thus it would seem that a planet may be the natural formation of an instant, requiring time for completion, and may be an everyday circumstance in space. The strict inquirer into terrestrial magnetism has to ascertain, whether the non-conducting central ice be not the means, some how, of separating the correlative fluids which the centripetal flow carries with it along the axis through the Poles, and which make the Poles magnetic opposites; or, whether, of these fluids, one only is transmissible through ice. A planet may be subject to wear and the fertility to decrease, thence to be uninhabitable, as Herschel describes the very probable condition of the moon, owing to the rapid motion through space, solar effects and cultivation. The idea is neither gloomy nor a threatened dread. Man was born to leave this world, and live where GOD has pleased. Some anticipate the night, when we shall see "our God in terror, and our world on fire!"--"undoing all, as all had never been," or made in vain. But He who blessed and never cursed his works, whose mercy and goodness endureth for ever, and who will "save both man and beast," is not a God of terror! Why the planets are moved round the sun, all in the same direction, excites speculation in the absence of demonstration. Let it be supposed that the inequalities in a newly-formed planet prevent the body being at rest under the general pressure; in which case the planet is put into its primeval motion, and in the direction of the strongest impulsive pressure. But as the like inequalities precisely, cannot present in every new planet, neither could the motion of all be in the same direction, which gives room for conceiving the probability that the portion of the medium, however extensive, in which the solar system is involved, revolves round the sun, or round the orbit of the sun, and that its motion is promoted by the sun in the solar orbit,--which orbit may probably be promoted by the rarity of the elements in the solar regions. The medium of space so revolving, determines the direction of all the planets, which by the hypothesis must be the same as that of the revolving medium.