hrough 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.

[Sidenote: * _Vid. Riccioli Almagest. novum_, Tom. 1, lib. 4. cap. 10. n.
111. pag. 216. 2.]

To help this, there is one (_Vid.* Jo. Baptista Balianus_) who makes 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 _Menstrual_
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 {271} the Observations of Mr. _Hook_
made in _February_ and _March_ last, and by him communicated to the _Royal
Society_, and since Printed in the _Transactions_, published _Apr._ 2.
1666. consonant to the like observations of _Jupiter_, made by him in
_May._ 1664, and since communicated to the same _Society_; and then
published in the _Transactions_, of _March._ 6. then next follo