A Discourse Presented to the Most Serene Don Cosimo II., Great Duke of Tuscany, Concerning the Natation of Bodies Vpon, and Submersion In, the Water.Galilei, Galileo
Science
A Discourse Presented to the Most Serene Don Cosimo II., Great Duke of Tuscany, Concerning the Natation of Bodies Vpon, and Submersion In, the Water.
Galilei, Galileo
Hydrostatics; Specific gravity
He passeth next to confute _Democritus_[82], which, by his Testimony would
have it, that some Fiery Atomes, which continually ascend through the
water, do spring upwards, and sustain those grave Bodies, which are
very broad, and that the narrow descend to the bottom, for that but a
small quantity of those Atomes, encounter and resist them.
[82] _Aristot. De Cælo_ lib. 4. cap. 6. text. 43.
I say, _Aristotle_ confutes this position[83], saying, that that should
much more occurre in the Air, as the same _Democritus_ instances
against himself, but after he had moved the objection, he slightly
resolves it, with saying, that those Corpuscles which ascend in the
Air, make not their _Impetus_ conjunctly. Here I will not say, that
the reason alledged by _Democritus_ is true[84], but I will only say, it
seems in my judgement, that it is not wholly confuted by _Aristotle_,
whilst he saith, that were it true, that the calid ascending Atomes,
should sustain Bodies grave, but very broad, it would much more be
done in the Air, than in Water, for that haply in the Opinion of
_Aristotle_, the said calid Atomes ascend with much greater Force and
Velocity through the Air, than through the water. And if this be so,
as I verily believe it is, the Objection of _Aristotle_ in my
judgement seems to give occasion of suspecting, that he may possibly
be deceived in more than one particular: First, because those calid
Atomes, (whether they be Fiery Corpuscles, or whether they be
Exhalations, or in short, whatever other matter they be, that ascends
upwards through the Air) cannot be believed to mount faster through
Air, than through water: but rather on the contrary, they peradventure
move more impetuously through the water, than through the Air, as hath
been in part demonstrated above. And here I cannot finde the reason,
why _Aristotle_ seeing, that the descending Motion of the same
Moveable, is more swift in Air, than in water, hath not advertised us,
that from the contrary Motion, the contrary should necessarily follow;
to wit, that it is more swift in the water, than in the Air: for since
that the Moveable which descendeth, moves swifter through the Air,
than through the water, if we should suppose its Gravity gradually to
diminish, it would first become such, that descending swiftly through
the Air, it would descend but slowly through the water: and then
again, it might be such, that descending in the Air, it should ascend
in the water: and being made yet less grave, it shall ascend swiftly
through the water, and yet descend likewise through the Air: and in
short, before it can begin to ascend, though but slowly through the
Air, it shall ascend swiftly through the water: how then is it true,
that ascending Moveables move swifter through the Air, than through
the water?
[83] _Democritus_ confuted by _Aristotle_, text 43.
[84] _Aristotles_ confutation of _Democritus_ refuted by the
Author.
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