Book IV. of Natural Philosophy . 249

It is to be observ’d, when only the Part E F of *300the Line E S is consider’d, that it is to be lo-ok’dUpon as parallel to the Line L /, because of thesmall Angle which these Lines make; from thePoint N draw N Q_ perpendicular to the Line 1301F T, continu’d if need be, in which the Moongravitates towards the Earth, and let the rectan-gular Parallelogram E P N Q^be drawn ; let usconceive the Force along F N resolv’d into twoothers, acting in the Directions F Qand F P, andrepresented by these Lines* ; by the Force along * 192F Q^the Force of Gravity is diminished in theCafe represented by this Figure, but it is increa-sed when the Point falls between F and Tbut by the Force along F P the Moon in its Orbitis drawn towards the next Syzygy L, and theMotion of the Moon is accelerated or retarded,according as this Force conspires with, or actscontrary to the Moon’s Motion.

Near a Syzygy the Gravity of the Moon is di-rninilh’d, and the Line F CL, which follows theProportion of this Diminution, grows less, rece-ding from the Syzygy, till it vanishes at the di-stance of about A4 Deg. 44 Min. from it; at agreater distance of the Moon from the SyzygyQ falls in between F and T, and the Gravity ofthe Moon towards the Earth is increas’d by theSun’s Action; the Force along F P vanishes inthe Syzygy L; receding from it, it increases quiteto the Octant, which is the middle Point betweenthe Syzygy and the Quadrature ; and then it di-minishes again, till it vanishes quite at B.

Between B and I, or I and A, the disturbing ,1302Motions are determin’d in the same manner as inALB, the opposite inferior Part of the Orbit;at E and F the Diminution of Gravity is equal,and in that Position it is drawn in the Orbit with

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