( 2J0 ) 
“ C f D C» may be eafily prov’d from the Confideration 
or inclin d I lanes) but the Centrifugal Force at C 
being to the Centrifugal Force at d, as C D is to O Q, 
“ (that is, as jy is to r) the Centrifugal Force at C will 
“ be e d ual t0 n ~~ i and becaufe the Centrifugal Force of 
each Particle is as its Diflance from the Point D 
which is the Center of the Circle that the Fluid in 
“ tbe Canal C D defcribes, and therefore the Centrifugal 
“ ^ o^ces, in counting from the Point D, mull encreafe 
in an Arithmetical Progreflion, the greatefl of which 
“ 18 — > and therefore the Sum of all the Centrifugal 
“ Forces in C D muft be equal to n -Al y therefore the 
• i r 
“ Weight of the Canal O C isf== / 1 
<c n yy 
= fr — i nr, which Equation exprefles the 
“ Nature of the Curve that is made by the Se&ion of 
the Earth with a Plane through its Poles, and by this 
<c the Proportion of the Axis of the Earth, to the Dia- 
meter of the fEquator, may beealily determin’d ; for 
“ when C O coincides with O P, then C D or ^ be- 
comes equal to nothing, and the Equation is/ -y/ x z 
“ ==fr — \nr or / * =/ r — \ nr, and therefore 
ct b y the i6th of the 6th, /has the fame Proportion to 
“ that r has to ^orOQ.toO D, but / is to 
— \n as 289 is to 288*, or as 578 is to 577, which 
“ therefore is the Proportion of the greatefl Diameter of 
u *b e ^ ar th to the lead ; but this is upon Suppolition, 
) that Gravity is the fame at all Dillances from the 
Center ^ but if we will fuppofe, that the Gravity of 
Bodies without the Earth is in a Proportion reciprocal 
“ to the Squares of their Diflances from the Center, the 
a 
