[ 4*4 ] 
admitted Gravity as a Principle; befides that it 
would give the true Caufe of Hardnefs, its Combi- 
nation with the ftrait or projeftile Motion v/ould 
produce a Motion in a Curve ; as Sir Ifaac New- 
ton has demonftrated. But until they will return to 
this Idea of primitive Gravity, and further while they 
will make ufe of no other Matter than one infinitely 
foft, and really unintelligible, it will not be poflible 
to conceive a fingle Vortex formed j far from having 
this infinite Number, which, by-the-bye, ought to 
be diflipated as Waves raifed in the Water, upon 
account of their perfed Homogeneity. 
The famous Cartejians^ always refufing to allow 
this primitive Gravity, and at the fame time plainly 
feeing, that this firfl; Manner of forming the Vortex 
was impoflible, have had recourfe, in order to its 
Formation, to the Motion of Rotation of a folid 
Sphere at the Centre of a fmall Particle of Matter 
at Reft, and they have pretended, that this Sphere 
in its Circulation ought to carry along with it the 
circumambient Matter. 
But this Notion is certainly as unfuftainable as the 
Firft. For, 
jjiy They muft explain to us the mechanical For- 
mation of this Sphere; they muft account for its 
Solidity : But all this manifeftly fuppofes the Vortex 
already formed ; all this fuppofes a Prefllire equal on 
every Side, uniform and concentric. 
idly. This Sphere would never imprint an equal 
Velocity on all the Points of the concave Surface 
which touches and inclofes it, feeing itfelf has not 
an equal Velocity in every Point of its laft Surface; 
and therefore the Vortex would not have as much 
Force 
