** No part of an element has gravity or levity within its own element. / ** Gravity and levity is caused - they are 2 equal and contrary powers in their motions - they are 2 contrary actions, equal in power and various in their motions, which are caused by one element being drawn into another. / ** The central line is a potential straightness that extends between the center of the suspended heavy body and the center of the world. / ** The mathematical plane is so conditioned that, a straight line being drawn upon it, that line is wholly contingent (touching) with that plane. / ** The natural plane has every part of it of equal height, and it does not touch the mathematical plane except at a point, and the straight line extended over it joins with it at a point. / ** The mathematical plane has every part of it of unequal height, and the straight line that touched its extremities comes to touch that plane along its whole length. / ** The spheric body will not come to rest except upon the middle of the mathematical plane. / ** The junction of the natural plane with the mathematical is made at a point. / ** The spheric body will come to rest at every point of the natural plane. / ** That thing is higher which is more remote from the center of the world, and the lower one is nearer to that center. / ** The spheric body will come to rest at that point of the mathematical plane which is nearest to the center of the world. / ** The heavy spheric body will not rest upon the natural plane unless the central line passes through the point of its contact. / ** No part of an element has gravity or levity within its own element. / ** Gravity and levity are two actions equal in power and contrary in their motions, and are caused by one element being drawn into another. / ** 9. - The central line is a potential straightness that extends between the natural or accidental center of the suspended heavy body and the center of the world. / ** 10. - Every body of irregular figure has 3 centers, of which one is the center of natural gravity, another of accidental gravity, and the third is of magnitude and ... / ** Every uniform body has the center of natural and accidental gravity and of magnitude in one same point. / ** 11. - In bodies of uniform figure the center of natural gravity and of magnitude are concentric. / 3. - That thing is higher which is more distant from the center of the world, and the lower one nearer to that center. / 4. - The natural plane has every part of it of equal height (** and the contact it has with the straight line is made at a point). / 5. - The mathematical plane has every part of it of unequal height (** and it touches along the whole line that touches it at the extremities). / ** The contact of the natural plane with the mathematical plane is made at a point. / 7. - The spheric body, placed at the extremity of the mathematical plane, will run at once to the middle of that plane and there come to rest, so as to be nearer the center of the world. - And this addition is put as commentary. / 6. - The spheric body, placed upon any part of the natural plane, will immediately come to rest, and this it does because it is always equally distant from the center of the world. - Commentary. / 8. - The spheric body will not come to rest upon the mathematical plane unless its central line passes through the point of contact. / 1. - No part of an element has gravity or levity within its own element. / 2. - Gravity and levity are two accidental actions, equal in power and contrary in their motions, created by one element being drawn or pushed into another. / 9. - The central line is a potential straightness that extends between the natural or accidental center of the suspended heavy bodies and the center of the world. / 10. - Every body of irregular figure has 3 centers, of which one is the center of natural gravity, another of the accidental, and the third of magnitude. / 11. - In bodies of uniform figure the center of natural gravity and of magnitude are concentric. / The spheric body is a figure contained by a single surface, and that is bounded by an equal curve on every part ... and is in every ... / The spheric body is a figure contained by a single surface, and that from every part bounds ... that sphere with equal curvature, and its intrinsic middle is called [the center], from which straight lines drawn to its surface will all be of equal length.

Draw a vessel of water through the air: all that water weighs in the air, and no part of that water has gravity within its whole. / Draw air beneath the water: all the air will be light, and in itself no part has levity or heaviness.

21-21

12-12. Power of greater levity against lesser levity.