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

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SALV. I have aſſumed for a truth, that the velocities of
bles
deſcending naturally, vvill follovv the proportion of their
vities
, with the favour of Simplicius, and of Ariſtotle, who doth
in
many places affirm the ſame, as a propoſition manifeſt: You,
in
favour of my adverſary, bring the ſame into queſtion, and ſay
that
its poſſible that the velocity increaſeth with greater
tion
, yea and greater in infinitum than that of the gravity; ſo that
all
that hath been ſaid falleth to the ground: For maintaining
whereof
, I ſay, that the proportion of the velocities is much leſſe
than
that of the gravities; and thereby I do not onely ſupport
but
confirme the premiſes.
And for proof of this I appeal unto
experience
, which will ſhew us, that a grave body, howbeit thirty
or
fourty times bigger then another; as for example, a ball of
lead
, and another of ſugar, will not move much more than twice
as
faſt.
Now if the projection would not be made, albeit the
locity
of the cadent body ſhould diminiſh according to the
portion
of the gravity, much leſſe would it be made ſo long as the
velocity
is but little diminiſhed, by abating much from the
ty
.
But yet ſuppoſing that the velocity diminiſheth with a
tion
much greater than that wherewith the gravity decreaſeth, nay
though
it were the ſelf-ſame wherewith thoſe parallels conteined
between
the tangent and circumference do decreaſe, yet cannot I
ſee
any neceſſity why I ſhould grant the projection of matters of
never
ſo great levity; yea I farther averre, that there could no ſuch
projection
follow, meaning alwayes of matters not properly and
abſolutely
light, that is, void of all gravity, and that of their own
natures
move upwards, but that deſcend very ſlowly, and
have
very ſmall gravity.
And that which moveth me ſo to think
is
, that the diminution of gravity, made according to the
tion
of the parallels between the tangent and the circumference,
hath
for its ultimate and higheſt term the nullity of weight, as thoſe
parallels
have for their laſt term of their diminution the contact it
ſelf
, which is an indiviſible point: Now gravity never diminiſheth
ſo
far as to its laſt term, for then the moveable would ceaſe to be
grave
; but yet the ſpace of the reverſion of the project to the
circumference
is reduced to the ultimate minuity, which is when
the
moveable reſteth upon the circumference in the very point of
contact
; ſo as that to return thither it hath no need of ſpace:
and
therefore let the propenſion to the motion of deſcent be

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