On _AB_, the Axis of the Handle _H_, is an endless Screw _C_ which turns
the Wheel _FED_ of 24 teeth round in 24 revolutions of the Handle: this
Wheel turns another _ONG_ of 48 teeth, and on its Axis is the Pinion
_PQ_ of four leaves which turns the Wheel _LKI_ of 59 teeth round in
29-1/2 turnings or rotations of the Wheel _FED_, or in 708 revolutions
of the Handle, which is the number of Hours in a synodical revolution of
the Moon. The round Plate with the names of Places upon it is fixed on
the Axis of the Wheel _FED_; and the Elliptical or Tide-Plate with the
Moon fixed to it is upon the Axis of the Wheel _LKI_; consequently, the
former makes 29-1/2 revolutions in the time that the latter makes one.
The whole Wheel _FED_ with the endless Screw _C_, and dotted part of the
Axis of the Handle _AB_, together with the dotted part of the Wheel
_ONG_, lie hid below the large Wheel _LKI_.
Fig. 9th represents the under side of the Elliptical or Tide-Plate
_abcd_, with the four small Plates _ABCD_, _EFGH_, _IKLM_, _NOPQ_ upon
it: each of which has two slits as _TT_, _SS_, _RR_, _UU_ sliding on two
Pins as _nn_, fixed in the elliptical Plate. In the four small Plates
are fixed four Pins at _W_, _X_, _Y_, and _Z_; all of which work in an
elliptic Groove _oooo_ on the cover of the Box below the elliptical
Plate; the longest Axis of this Groove being in a right line with the
Sun and Full Moon. Consequently, when the Moon is in Conjunction or
Opposition, the Pins _W_ and _X_ thrust out the Plates _ABCD_ and _IKLM_
a little beyond the ends of the elliptic Plate at _d_ and _b_, to _f_
and _e_; whilst the Pins _Y_ and _Z_ draw in the Plates _EFGH_ and
_NOPQ_ quite under the elliptic Plate to _g_ and _h_. But, when the Moon
comes to her first or third Quarter, the elliptic Plate lies across the
fixed elliptic Groove in which the Pins work; and therefore the end
Plates _ABCD_ and _IKLM_ are drawn in below the great Plate, and the
other two Plates _EFGH_ and _NOPQ_ are thrust out beyond it to _a_ and
_c_. When the Moon is in her Octants the Pins _V, X, Y, Z_ are in the
parts _o, o, o, o_ of the elliptic Groove, which parts are at a mean
between the greatest and least distances from the Center _q_, and then
all the four small Plates disappear below the great one.
[Sidenote: The ECLIPSAREON.