g
liquor, and the _bigness of the holes_ of the pipes.

_AN ATTEMPT FOR THE EXPLICATION OF THIS EXPERIMENT._

My Conjecture, _That the unequal height of the surfaces of the water,
proceeded from the greater pressure made upon the water by the Air without
the Pipes_ ABC, _then by that within them_[8]; I shall endeavour to confirm
from the truth of the two following _Propositions_:

The first of which is, _That an unequal pressure of the incumbent Air, will
cause an unequal height in the water's Surfaces_.

And the second is, _That in this experiment there is such an unequal
pressure_.

That the first is true, the following _Experiment_ will evince. For if you
take any Vessel so contrived, as that you can at pleasure either _increase_
or _diminish_ the _pressure_ of the Air upon this or that part of the
_Superficies_ of the _water_, the _equality_ of the height of those parts
will presently be _lost_; and that part of the _Superficies_ that sustains
the _greater pressure_, will be _inferior_ to that which undergoes the
_less_. A fit Vessel for this purpose, will be an inverted Glass _Syphon_,
such an one as is described in the _Sixth Figure_. For if into it you put
Water enough to fill it as high as _AB_, and gently blow in at _D_, you
shall _depress_ the Superficies _B_, and thereby _raise_ the opposite
Superficies _A_ to a _considerable height_, and by gently _sucking_ you may
produce clean _contrary_ effects.

Next, That there is such an _unequal pressure_, I shall prove from this,
_That there is a much greater incongruity of Air to Glass, and some other
Bodies, then there is of Water to the same_.

By _Congruity, I mean a property of a fluid Body, whereby any part of it is
readily united with any other part, either of itself, or of any other
Similar, fluid, or solid body: And by Incongruity a property of a fluid, by
which it is hindred from uniting with any dissimilar, fluid, or solid
Body._

This last property, any one that hath been observingly conversant about
fluid Bodies, cannot be ignorant of. For (not now to mention several
_Chymical Spirits_ and _Oyls_, which will _very hardly_, if at _all_, be
brought to _mix_ with one another; insomuch that there may be found some 8
or 9, or more, several distinct Liquors, which _swimming_ one upon another,
will not presently _mix_) we need seek no further for Examples of this kind
in _fluids_, then to observe the _drops of rain_ falling through the _air_
and the _b