left behind, after the Spark was gone out, I purposely struck fire over a
very white piece of Paper, and observing diligently where some conspicuous
sparks went out, I found a very little black spot no bigger then the point
of a Pin, which through a _Microscope_ appeared to be a perfectly round
Ball, looking much like a polisht ball of Steel, insomuch that I was able
to see the Image of the window reflected from it. I cannot here stay
(having done it more fully in another place) to examine the particular
Reasons of it, but shall only hint, that I imagine it to be some small
parcel of the Steel, which by the violence of the motion of the stroke
(most of which seems to be imprest upon those small parcels) is made so
glowing hot, that it is melted into a _Vitrum_, which by the ambient Air is
thrust into the form of a Ball.

A Fifth thing which I thought worth Examination was, Whether the motion of
all kind of Springs, might not be reduced to the Principle whereby the
included _heterogeneous fluid_ seems to be moved; or to that whereby two
Solids, as Marbles, or the like, are thrust and kept together by the
_ambient fluid_.

A Sixth thing was, Whether the Rising and Ebullition of the Water out of
Springs and Fountains (which lie much higher from the Center of the Earth
then the Superficies of the Sea, from whence it seems to be derived) may
not be explicated by the rising of Water in a smaller Pipe: For the
Sea-water being strained through the Pores or Crannies of the Earth, is, as
it were, included in little Pipes, where the pressure of the Air has not so
great a power to resist its rising: But examining this way, and finding in
it several difficulties almost irremovable, I thought upon a way that would
much more naturally and conceivably explain it, which was by this following
Experiment: I took a Glass-Tube, of the form of that described in the sixth
Figure, and chusing two _heterogeneous fluids_, such as Water and Oyl, I