; . C m ] 
the Ellipfe with their Ordinates, and the circumfcribed 
Parallelogram ; parallel Lines in the Plane of this Circle 
are projected by Parallels in the Plane of the Ellipfe 
that are in the fame Ratio ; any Area in the former is 
projected by an Area in the latter, which is in an 
invariable Ratio to it; and concentric Circles give 
fimilar concentric Ellipfes.. It is likewife fhewn how 
Properties of a certain kind are briefly transferred from . 
the Circle to any conic Se&ion with the fame Facility. 
After demonftrating the Properties of the Ellipfe, 
it is^fhewn, that if the Gravity of any Particle of a 
Spheroid being refolved into two Forces, one perpem 
dicular to the Axis of the Solid, the other perpen- 
dicular to the Plain of its Equator, then all Particles, 
equally diflant from the Axis, muft tend towards it 
with equal Forces ; and all Particles at equal Diftances 
from the Plain of the Equator, gravitate equally to- : 
wards this Plain ; but that the Forces with which Par- 
ticles at different Diftances from the Axis tend towards - 
it, are as the Diftances ; and that the fame is to be 
faid of the Forces with which they tend towards the . 
Plain of the Equator. 
From this it is demonftrated, that when the Par- 
ticles of a fluid Spheroid of an uniform Denfity gra- 
vitate towards each other with Forces that are in- 
verfely as the Squares of their Diftances, and at the 
fame time any other Powers a ft on the Particles, either 
in right Lines perpendicular to the Axis, that vary in 
the fame Proportion as the Diftances from the Axis, ; 
or in right Lines perpendicular to the Plain of the. 
Equator, that vary as their Diftances from it,, or when ^ 
any Powers ad on the Particles of the Spheroid, that , 
may be refolved into Forces of this kind ; then the. 
' ' Fluid.; 
