Newton imagined that a medium, and however rare, occupying the regions of space, must retard, in time destroy, and eventually require the hand of Deity to restore the primeval order of planetary motion: no very bright idea of the great mathematician, considering the Omniscience of the Projector of a _self-going_, _self-regulating_ Universe. Whereas a medium as dense as molten gold, could produce no such disorder as long as impulse is greater than resistance; which the long-continuance and order of planetary motion strongly seem to indicate is the case. Were there no medium in space, the planets must be at rest; one could not possibly affect another but by its shadow: Uranus being agitated by the greatly remote presence of Neptune, is proof of there being a connecting medium between. Gravitation is supposed to move the body possessed of the property, forwards,--why not every way?--to the sun or towards some neighbouring planet, but not to send that body or planet an agitating warning of its presence. How is gravitation within one planet to keep another in a state of agitation; which agitation being motion--a mechanical effect--is proof of there being a medium by which mediate connection is maintained between the two, Uranus and Neptune. Without a planetary medium there could be no _system_ of planets. Suppose the existence of such a medium, then its sudden removal,--must not every subordinate system, which makes part of the universal system, become disjointed the same instant? Besides, from the laws of vision, rather of optics, there is equal proof that space contains a medium. There is no light to come from a star to the eye; there is nothing of sight belonging to the eye-balls; and there must be something between a star and the sense to connect the star with the sense; or how is the sense or brain to be so affected by the star, as that the perception or sensation shall be always the same when the eye-ball lenses are directed to the same star; and only by a universal medium can all the stars of the hemisphere be in connection with the eye at the same time, or the time of a few winks of the eye. Therefore until it is proved that constant planetary motion can be without constant and equal corresponding impulse, as to direction; and that a star can affect the sense of itself, immediately or with nothing between, all denial of planetary space being occupied by a medium of pressure, is utterly untenable. THE MEDIUM OF SPACE. Pressure being obviously the cause of planetary motion, so is it of all terrestrial motion. To produce atomic motion and transfer generally, it is necessary, only, that the atoms of the medium of space should be of less size than the minutest interstices in bodies.