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appendix i.

319

hatersgarth’s

Motion of the Moon aboutEarth is similar to that ofof the Ocean revolving aboutCentre. To shew this, some

T he

the'he

; /jf S Duh be premised; as, first, 'Thatfy tra &i° n of the Earth upon any Par-V ^ ater 2S the fame 01 s 2t would be ,

;f thefame Quantity of Matter con-^ k T i nt0 a p 0 i n t in its Centre. For let^ O be the Earth, C its Centre, P a Fig. 6.i^^e at any Distance P A from its Sur-^' let P G be drawn through P and C,

0 ^ O the Diameter of any Circle B D1^ ' °f Section of the Sphere perpendicu-to Axis PO.

PlateL XVIII.

*8

h

the

N«

0\V put

PN‘ -

PN

, Cl+

X

BPal’— B N\

-x; thenwhich is

t t ^p e ^ rea of the Circle B D O E; the at-|w , ltl § Force whereof is 2 x x, and is pro-l0r *al to the Quantity of Matter or^Un ber °f Particles which act on the Cor-*e P in the Periphery of the Area, and

in