Page:Philosophical Transactions - Volume 001.djvu/282

 in this it comes short; that as it gives an Account of two Tides; so those two Tides are alwayes to be at F and D; that is, at Noon and Midnight whereas Experience tells us, that the Time of Tides, moves in a moneths space through all the 24. hours. Of which he gives us no account. For though he do take notice of a Menstrual Period; yet he doth it onely as to the Quantity of the Tides; greater or less; not as to the Time of the Tides, sooner or later.

To help this, there is one (Vid. * Jo. Baptista Balianus) who make the Earth to be but a secondary Planet; and to move, not directly about the Sun, but about the Moon, the Moon meanwhile moving about the Sun; in like manner as we suppose the Earth to move about the Sun, and the Moon about it.

But this, though it might furnish us with the foundation of a Mentrual Period of Accelerations and Retardations in the compound motion of several parts of the Earths surface; yet I am not at all inclined to admit this as a true Hypothesis, for divers Reasons, which if not demonstrative, are yet so consonant to the general Systeme of the World, as that we have no good ground to disbelieve them. For 1. The Earth being undeniably the greater Body of the two (whereof there is no doubt to be made) it cannot be thought probable, that this should be carried about by the Moon, lesser than it self: The contrary being seen, not onely in the Sun, which is bigger than any of the Planets, which it carryes about; but in Jupiter, bigger than any of his Satellites; and Saturne, bigger than his. 2. As the Sun by it's motion about it's own Axis, is with good reason judged to be the Physical cause of the Primary Planets moving about it; So there is the like reason to believe, that Jupiter and Saturne moving about their Axes, are the Physical cause of their Satellites moving about them, which motion of Jupiter hath been of late discover'd, by the help of a fixed Spot discern'd in him; and we have reason to believe the like of Saturne. Whether Venus and Mercury (about whom no Satellites have been yet observed) be likewise so moved; we have not yet the like ground to determine: But we have of Mars; from Rh