Archimedes Texts

156
bubbles, the greater they will grow, be
cause having the less weight and pressure
upon them, the Expansion of that Air
which makes them, can be the less resisted
by the pressure of the incumbent Water
and Air; as seems probable from hence,
that upon the letting in a little external
Air, those bubbles immediately shrink.

It may indeed, as we lately intimated,
be conjectur'd, that these bubbles pro
ceed not so much from any Air pre-exi
stent in the Water, and lurking in the
Pores of it, as from the more subtle parts
of the Water it self; which by the expan
sion allow'd them upon the diminish'd
pressure of the ambient Bodies may gene
rate such bubbles. And indeed, I am not
yet so well satisfied that bubbles may not
(at least sometimes) have such an Origina
tion: but that which makes me suspect
that those in our tryals contain'd real Air
formerly latitant in the Pores of the Wa
ter, is this, That upon the inletting of
the external Air, the Water was not
again impell'd to the very top of the
Tube whence it began to fall, but was
stopt in its ascent near an Inch beneath
the top. And since, if the upper part of
the Tube had been devoyd of any other