ose the Earth carried
about with a double motion; The one _Annual_, as (_Fig._ 1.) in B E C the
great Orb, in which the Center of the Earth B, is supposed to move about
the Sun A.

The other _Diurnal_, whereby the whole moves upon its own _Axis_, and each
point in its surface describes a Circle, as D E F G.

It is then manifest, that if we suppose, that the Earth moved but by any
one of these motions, and that regularly, (with an equal swiftness;) the
Water, having once attained an equal _Impetus_ thereunto, would still hold
equal pace with it; there being no occasion, from the Quickening or
Slackening of the Earths motion, (in that part where the Water lyeth) for
the Water thereon either to be cast Forward or fall Backward; and thereby
to accumulate on the other parts of the Water: But the true motion of each
part of the Earths surface being compounded of those two motions, the
_Annual_ and _Diurnal_; (the _Annual_ in B E C being, as _Galilaeo_ there
supposeth, about three times as fast as a _diurnal_ motion in a great
Circle, as D E F;) while a Point in the Earths surface moves about its
Center B. from G. to D. and E. and at the same time, its Center B. be
carried forwards to C; the true motion of that Point forwards, is made up
of both those motions; to wit, of B to C, and of G to E; but while G moves
by D to E, E moves backward by F to G, contrary to the motion of B to C; so
that the true motion of E, is but the difference of B C, and E G: (for,
beside the motion of B above the Center; G. is also put forward as much as
from G to E; and E put backward as much as from E to G:) so that the
_Diurnal_ motion, in that part of the Earth, which is next the Sun, as E F
G, doth abate the progress of the _Annual_, (and most of all at F;) and in
the other part, which is from the Sun, as G D E, it doth increase it, (and
most of all at D.) that is, in the day time there is abated, in the night
time is added to the _Annual_ motion, about as much as is G E, the Earths
_Diameter_. Which would afford us a Cause of two Tides in twenty four
hours; the One upon the greatest Acceleration of motion, the Other upon its
greatest Retardation.

And thus far _Galilaeo_'s Discourse holds well enough; But then {270} 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_ t