a68 Mathematical Elements Book IV.

* 976 dies*, therefore the Axis P P is 3,393,261, and

the equatorial Diameter Ee is 3,408,078 Perches,which exceeds the Axis by 14,817 Perches (viz.)

1368 - 2 ~- t and the Equator is more elevated by 7408,5.

In this Computation, as we have said, we havey look’d upon the Earth as homogeneous ; but if itbe more dense towards the Center, the Matterwhich is added to it may be look’d upon as a se-parate Body, from whose Center the Points P andE are unequally distant, and towards which there-fore the Bodies P and E have a different Gravi-

*1226 ty* ; and the difference is so much the greater asthese differences are greater ; and it will be alsoso much the greater in respect of the whole Gra-vity, as the Quantity of Matter which is added,or which is the fame, as the Density is greater to-wards the Center.

It is plain that the Forces of Gravity at thePoles and the Equator differ from one anothermore than a-f? Part, by comparing together Ex-periments made at several Distances from theEquator by the help of Pendulums, by which theForces of Gravity may be compar’d together, as

* 164 we have shewn*, and which difference is truly165 nearly double that which is found by Computa-

1370 tion ; whence it follows, that the Elevation of theEquator is nearly double that which we have deter -

*1368 inin’d to be 7408,5 Perches*.

Now if we consider the spheroidical Figure of

1 37 1 the Earth, we shall see that heavy Bodies do not tenddirectly to the Earth’s Center, unless at the Polesand the Equator, but every where perpendicularly tothe Surface of the Spheroid ; for a Liquid will notbe at rest unless its upper Surface forms a right

* 272 Angle with the Direction of heavy Bodies* ; an< *

the Figure of a Spheroid is form’d by the Surface

of a quiescent Fluid. We also deduce this Di re<

ction