52. If it be a Perpendicular upwards; then the difference of these two represents the Motion; which so long as _KQ_ is the greater, is Ascendent; but Descendent, when _hQn_ becomes greater; and it is then at the highest when they be equal. 53. If the Projection be not in the same Perpendicular, (but Horizontal, or Oblique) then _KQ_ represents the Tangent of the Curve; and _hQn_ the Ordinates to that Tangent, at the given Angle. 54. But the Computation before given, I take to be of better use than this Representation in Figure. Because in such Mathematical Enquiries, I choose to separate (as much as may be) what purely concerns Proportions; and consider it abstractly from Lines, or other Matter wherewith it is incumbred. As to the Question proposed; whether the resistance of the _Medium_ do not always take off such a proportional part of the Force moving through it, as is the specifick Gravity of the _Medium_ to that of the Body moved in it: (For, if so, it will save us the trouble of Observation.) I think this can by no means be admitted. For there be many other things of Consideration herein, beside the intensive Gravity (or, as some call it, the specifick Gravity) of the _Medium_. A viscous _Medium_ shall more resist, than one more fluid, though of like intensive Gravity. And a sharp Arrow shall bore his way more easily through the _Medium_, than a blunt-headed Bolt, though of equal Weight, and like intensive Gravity. And the same Pyramid with the Point, than with the Base forward. And many other like Varieties, intended in my ¶ 48. But this I think may be admitted, namely, That different _Mediums_, equally liquid, (and other Circumstances alike,) do in such proportion resist, as is their intensive Gravity. Because there is, in such proportion, a heavier Object to be removed, by the same Force. Which is one of the things to which ¶ 33 refers. And again: The heavier Project once in Motion, (being equally swift, and all other Circumstances alike) moves through the same _Medium_ in such proportion more strongly, as is its intensive Gravity. For now the Force is in such proportion greater, for the removal of the same resistance. And this Part of what my ¶ 32, insinuates. But where there is a Complication of these Considerations one with another, and with many other Circumstances, whereof each is severally to be considered; there must be respect had to all of them. [14] R - 1_V_) _R_ (_V_ + _V/R_, _V/RR_, &c. _VR_ - V -------- + V + V/VR ------- + V/R + VV/RRR -------- + V/RR _&c_.