rned in the business of its hardening and tempering: of which somewhat
it said in the Description of _Muscovy-glass_.

So that, these things considered, we need not trouble our selves to find
out what kind of Pores they are, both in the Flint and Steel, that contain
the _Atoms of fire_, nor how those _Atoms_ come to be hindred from running
all out, when a dore or passage in their Pores is made by the concussion:
nor need we trouble our selves to examine by what _Prometheus_ the Element
of Fire comes to be fetcht down from above the Regions of the Air, in what
Cells or Boxes it is kept, and what _Epimetheus_ lets it go: Nor to
consider what it is that causes so great a conflux of the atomical
Particles of Fire, which are said to fly to a flaming Body, like Vultures
or Eagles to a putrifying Carcass, and there to make a very great pudder.
Since we have nothing more difficult in this _Hypothesis_ to conceive,
first, as to the kindling of Tinder, then how a large Iron-bullet, let fall
red or glowing hot upon a heap of Small-coal, should set fire to those that
are next to it first: Nor secondly, is this last more difficult to be
explicated, then that a Body, as Silver for Instance, put into a weak
_Menstruum_, as unrectified _Aqua fortis_ should, when it is put in a great
heat, be there dissolved by it, and not before; which _Hypothesis_ is more
largely explicated in the Description of Charcoal. To conclude, we see by
this Instance, how much Experiments may conduce to the regulating of
_Philosophical notions_. For if the most Acute _Des Cartes_ had applied
himself experimentally to have examined what substance it was that caused
that shining of the falling Sparks struck from a Flint and a Steel, he
would certainly have a little altered his _Hypothesis_, and we should have
found, that his Ingenious Principles would have admitted a very plausible
Explication of this _Phaenomenon_; whereas by not examining so far as he
might, he has set down an Explication which Experiment do's contradict.

But before I leave this Description, I must not forget to take notice of
the Globular form into which each of these is most curiously formed. And
this _Phaenomenon_, as I have elsewhere more largely shewn, proceeds from a
propriety which belongs to all kinds of fluid Bodies more or less, and is
caused by the Incongruity of the Ambient and included Fluid, which so acts
and modulates each other, that they acquire, as neer as is possible, a
_sph