A universal medium must be of universal service, (as would be conceived, were the universe involved in a medium of water,) to be in accordance with nature's economy: to keep the planets and matter in motion, to retain atoms together, and effect their separation occasionally, include the whole of action required by its service; more in this respect it cannot effect; nor is the common general procedure otherwise effected. Therefore in pressure, by the medium of space, consists the PRIMUM MOBILE: the beginning and end of all physical cause of action and of all physical effect. Pressure is nothing assumed, hypothetic, or unproven, like attraction and gravitation,--the justly dethroned imbecile usurpers of the imperial chair of philosophy for ages past. On barometric evidence alone, that pressure exists all round the globe is fully proved; and that it is indispensable to the maintenance of the existing general order, all must readily grant who reflect for an instant on the fatal consequences which the cessation of the general pressure, for only a few minutes, must cause. Hence it is no immediate question how the general pressure originated, how maintained, what the confining boundaries or _point d'appui_. Most likely it is the consequence of the motion of the planets themselves, surging through the ocean of space. As every performance of nature has some ulterior object in view, it is probable that the effect of the motion of a planet on the medium of space is tributary to the motion of another planet, and that the motion of the whole is a means of preventing the cessation of motion of any of the parts. Most likely the medium of space was not in a state of pressure at first; that planetary motion, however commenced, effected the state of pressure necessary for its continuance, and which would be useless beyond the precincts of planetary evolution: where pressure is not needed, of a certainty there is none. Hence the conclusion is warrantable, that the general pressure, however commenced, is maintained by not only the motion of the planets individually but in systems, through the ocean of space. The earth may be said to swim through the medium of space, and to be soaked with it as a submerged sponge is with water, and the portion within the globe of the earth, is continuous with the like medium in space generally. By which all parts of the interior of the globe are under the general pressure equally as the surface, and all terrestrial bodies subject to its vicissitudes.