[Sidenote: A Piramide or Cone, demitted with the Point downwards shal swim, with its Base downward shall sink.]
_A Piramide or Cone put into the Water, with the Point downward shall swimme, and the same put with the Base downwards shall sinke, and it shall be impossible to make it float._
Now the quite contrary would happen, if the difficulty of Penetrating the water, were that which had hindred the descent, for that the said Cone is far apter to pierce and penetrate with its sharp Point, than with its broad and spacious Base.
And, to demonstrate this, let the Cone be _A B C_, twice as grave as the water, and let its height be tripple to the height of the Rampart _D A E C_: I say, first, that being put lightly into the water with the Point downwards, it shall not descend to the bottom: for the Aeriall Cylinder contained betwixt the Ramparts _D A C E_, is equall in Mass to the Cone _A B C_; so that the whole Mass of the Solid compounded of the Air _D A C E_, and of the Cone _A B C_, shall be double to the Cone _A C B_: And, because the Cone _A B C_ is supposed to be of Matter double in Gravity to the water, therefore as much water as the whole Masse _D A B C E_, placed beneath the Levell of the water, weighs as much as the Cone _A B C_: and, therefore, there shall be an _Equilibrium_, and the Cone _A B C_ shall descend no lower. Now, I say farther, that the same Cone placed with the Base downwards, shall sink to the bottom, without any possibility of returning again, by any means to swimme.
[Illustration]
Let, therefore, the Cone be _A B D_, double in Gravity to the water, and let its height be tripple the height of the Rampart of water L B: It is already manifest, that it shall not stay wholly out of the water, because the Cylinder being comprehended betwixt the Ramparts _L B D P_, equall to the Cone _A B D_, and the Matter of the Cone, beig double in Gravity to the water, it is evident that the weight of the said Cone shall be double to the weight of the Mass of water equall to the Cylinder _L B D P_: Therefore it shall not rest in this state, but shall descend.
[Illustration]
