r Surfaces;
for taking a small Wine-glass, or such like Vessel, and pouring water
gently into it, you shall perceive the _surface_ of the water all the way
_concave_, till it rise even with the top, when you shall find it (if you
gently and carefully pour in more) to grow very _protuberant_ and _convex_;
the reason of which is plain, for that the _solid_ sides of the containing
body are no longer extended, to which the water does more readily adhere
then the air; but it is henceforth to be included with air, which would
reduce it into a _hemisphere_, but by reason of its _gravity_, it is
flatted into an _Oval_. _Quicksilver_ also which to _Glass_ is more
incongruous then _Air_ (and thereby being put into a _Glass-pipe_, will not
adhere to it, but by the more _congruous air_ will be forced to have a very
_protuberant_ surface, and to rise higher in a greater then a lesser Pipe)
this _Quicksilver_ to clean _Metal_, especially to _Gold_, _Silver_, _Tin_,
_Lead_, &c. _Iron_ excepted, is more _congruous_ then _Air_, and will not
only stick to it, but have a _concave_ Surface like _water_, and rise
higher in a less, then in a greater Pipe.

In all these Examples it is evident, that there is an _extraordinary_ and
_adventitious force_, by which the _globular_ Figure of the contained
_heterogeneous_ fluid is altered; neither can it be imagined, how it should
otherwise be of any other Figure then _Globular_: For being by the
_heterogeneous_ fluid equally _protruded_ every way, whatsoever part is
_protuberant_, will be thereby _deprest_. From this cause it is, that in
its effects it does very much resemble a _round Spring_ (such as a _Hoop_.)
For as in a _round Spring_ there is required an additional _pressure_
against two opposite sides, to reduce it into an _Oval_ Form, or to force
it in between the sides of a _Hole,_ whose _Diameter_ is less then that of
the _Spring_, there must be a considerable force or _protusion_ against
_the concave_ or inner side of the _Spring_; So to alter this _spherical_
constitution of an included fluid body, there is required more pressure
against opposite sides to reduce it into an _Oval_; and, to press it into
an _Hole_ less in _Diameter_ then it self, it requires a greater
_protrusion_ against all the other sides, What degrees of force are
requisite to reduce them into longer and longer _Ovals_, or to press them
into less and less _holes_, I have not yet experimentally calculated; but
thus much b