Salusbury, Thomas, Mathematical collections and translations (Tome I), 1667

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1been partaker, as part of the ſhip, at the time that it was upon
the Maſt; the other is the new motion of deſcent, which alſo
muſt needs be an hinderance of that other progreſſive motion.
SALV. As to the impediment of the Air, I do not deny it
you; and if the thing falling were a light matter, as a feather,
or a lock of wool, the retardation would be very great, but in
an heavy ſtone is very exceeding ſmall.
And you your ſelf but
even now did ſay, that the force of the moſt impetuous wind
ſufficeth not to ſtir a great ſtone from its place; now do but
ſider what the calmer air is able to do, being encountred by a
ſtone no more ſwift than the whole ſhip.
Nevertheleſſe, as I ſaid
before, I do allow you this ſmall effect, that may depend upon
ſuch an impediment; like as I know, that you will grant to me,
that if the air ſhould move with the ſame velocity that the ſhip
and ſtone hath, then the impediment would be nothing at all.
As to the other of the additional motion downwards; in the firſt
place it is manifeſt, that theſe two, I mean the circular, about
the centre, and the ſtreight, towards the centre, are not
ries, or deſtructive to one another, or incompatible.
Becauſe that
as to the moveable, it hath no repugnance at all to ſuch motions,
for you your ſelf have already confeſt the repugnance to be
gainſt the motion which removeth from the centre, and the
nation to be towards the motion which approacheth to the centre.
Whence it doth of neceſſity follow, that the moveable hath
ther repugnance, nor propenſion to the motion which neither
proacheth, nor goeth from the centre, nor conſequently is there
any cauſe for the diminiſhing in it the faculty impreſſed.
And
aſmuch as the moving cauſe is not one alone, which it hath
tained by the new operation of retardation; but that they are
two, diſtinct from each other, of which, the gravity attends
ly to the drawing of the moveable towards the centre, and the
vertue impreſs't to the conducting it about the centre, there
maineth no occaſion of impediment.
SIMPL. Your argumentation, to give you your due, is very
probable; but in reality it is invelloped with certain intricacies,
that are not eaſie to be extricated.
You have all along built upon

a ſuppoſition, which the Peripatetick Schools will not eaſily grant
you, as being directly contrary to Aristotle, and it is to take for
known and manifeſt, That the project ſeparated from the
cient, continueth the motion by vertue impreſſed on it by the
ſaid projicient, which vertue impreſſed is a thing as much
ſted in Peripatetick Philoſophy, as the paſſage of any accident
from one ſubject into another.
Which doctrine doth hold, as I
believe it is well known unto you, that the project is carried by
the medium, which in our caſe happeneth to be the Air. And