( P8 ) 
II. Of the Figure of the Earth, and the Variation 
of Gravity on the Surface, ‘By Mi'. James 
Stirling, F. S. [<SW Tab- Fig. 6.] 
T H E Centrifugal Force, arifing from the Diurnal 
Rotation of the Earth, deprefleth it at the 
Poles, and renders it protuberant at the Equator ; 
as has been lately advanced by Sir Ifaac Newton , 
and long ago by Tolybius , according to Strabo in 
the Second Book of his Geography. But although 
it be of an oblate Ipheriodical Shape, yet the kind 
of that Spheroid is not yet difcovered ; and therefore 
I fhall fuppofe it to be the common Spheroid gene- 
rated by the Rotation of an Ellipfis about its leiTer 
Axis ; although I find by Computation, that it is 
only nearly, and not accurately fuch. I lhall alfo fup- 
pofe the Denfity to be every where the fame, from 
the Center to the Surface, and the mutual Gravita- 
tion of the Particles towards one another to decreafe 
in the duplicate Ratio of their Diftances : And then 
the following Rules will follow from the nature of 
the Spheroid. 
i. Let AD BE be the Meridian of an oblate 
Spheroid, DE the Axis, AB the Diameter of the 
Equator, and C the Center. Take any Point on 
the Surface, as F, from which draw FC to the 
Center, F G, perpendicular to the Surface at F, 
meeting C B in G, and F H cutting the Line C G, 
fo that C H may be to G H as three to two. I fay 
that a Body at F will gravitate injJje DirectionF H j 
and 
