rth, as that of the Moon, are to describe several Epicycles. And, for
that Reason fails of giving any clear account of this _Menstrual_ Period.
(And in like manner, he proposeth the Consideration as well of the Earths
_Aphelium_ and _Perihelium_ as of the _AEquinoctial_ and _Solstitial_
Points, in order to the finding a Reason of the _Annual_ Vicissitudes; but
doth not fix upon any thing, in which himself can Acquiesce: And therefore
leaves it _in medio_ as he found it.)

It had been more agreeable to the Laws of _Staticks_, if he had, (as I do,)
so considered the _Earth_ and _Moon_ as two parts of the same movable, (not
so, as he doth, _aliam in Centro et sequentem praecise revolutionem axis,
aliam remotius ac velut in circumferentia_, but,) so, as to make neither of
them the Center, but both out of it, describing Epicycles about it: Like
as, when a long stick thrown in the Air, whose one end is heavyer than the
other, is whirled about, so as that the End, which did first fly foremost,
becomes hindmost; the proper line of motion of this whole Body is not that,
which is described by either End, but that, which is described by a middle
point between them; about which point each end, in whirling, describes an
Epicycle. And indeed, in the present case, it is not the Epicycle described
by the Moon, but that, described by the Earth, which gives the _Menstrual_
Vicissitudes of motion to the Water; which would, as to this, be the same,
if the Earth so move, whether there were any Moon to move or not; nor would
the Moons Motion, supposing the Earth to hold on its own course, any whit
concern the motion of the Water.

[Illustration]

But now, (after all our Physical, or Statical Considerations) the clearest
Evidence for this Hypothesis (if it can be had) will be from Celestial
Observations. As for instance; (see _Fig._ 5.) Supposing the Sun at S; the
Earths place in its Annual Orb at T; and _Mars_ (in opposition to the Sun,
or near it) at M: From whence _Mars_ should appear in the Zodiack at
[gamma], and will at Full moon be seen there to be; the Moon being at C and
the Earth at c; (and the like at the New-moon.) But if the Moon be in the
First quarter at A, and the Earth at a: _Mars_ will be seen, not at
[gamma], but at [alpha]; too slow: And when the Moon is at B, and the Earth
at b, _Mars_ will be seen at [beta]; yet too slow: till at the {289}
Full-moon, the Moon at C, the Earth at c, _Mars_ will be seen at [gamma],
its tru