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

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1part but with two onely: but if the ſame bow be uſed, it always
receiveth thence three degrees.
SIMP. It doth ſo; and for this reaſon, ſhooting with the
ſame bow in the chariots courſe, the ſhoots cannot be equal.
SALV. I had forgot to ask, with what velocity it is ſuppoſed in
this particular experiment, that the chariot runneth.
SIMP. The velocity of the chariot muſt be ſuppoſed to be one
degree in compariſon to that of the bow, which is three,
SALV. Very right, for ſo computation gives it. But tell me,
when the chariot moveth, doth not all things in the ſame move
with the ſame velocity?
SIMP. Yes doubtleſs.
SALV. Then ſo doth the ſhaft alſo, and the bow, and the ſtring,
upon which the ſhaft is nock't.
SIMP. They do ſo.
SALV. Why then, in diſcharging the ſhaft towards the courſe
of the chariot, the bow impreſſeth its three degrees of velocity on
a ſhaft that had one degree of velocity before, by means of the
chariot which tranſported it ſo faſt towards that part; ſo that in
its going off it hath four degrees of velocity.
On the contrary,
in the other ſhoot, the ſame bow conferreth its ſame three degrees
of velocity on a ſhaft that moveth the contrary way, with one
gree; ſo that in its departing from the bow-ſtring, it hath no more
left but onely two degrees of velocity.
But you your ſelf have
already ſaid, that the way to make the ſhoots equal, is to cauſe
that the ſhaft be let flie the firſt time with four degrees of velocity,
and the ſecond time with two.
Therefore without changing the
bow, the very courſe of the chariot is that which adjuſteth the

flights, and the experiment doth ſo repreſent them to any one who
is not either wilfully or naturally incapable of reaſon.
apply this diſcourſe to Gunnery, and you ſhall find, that whether the
Earth move or ſtand ſtill, the ſhots made with the ſame force, will
always curry equal ranges, to what part ſoever aimed.
The error
of Ariſtotle, Ptolomey, Iycho, your ſelf, and all the reſt, is
ed upon that fixed and ſtrong perſuaſion, that the Earth ſtandeth
ſtill, which you have not judgment nor power to depoſe, no not
when you have a deſire to argue of that which would enſue,
ſuppoſing the Earth to move.
And thus, in the other argument,
not conſidering that whil'ſt the ſtone is upon the Tower, it doth,
as to moving or not moving, the ſame that the Terreſtrial Globe
doth, becauſe you have concluded with your ſelf, that the Earth
ſtands ſtill, you always diſcourſe touching the fall of the ſtone, as
if it were to depart from reſt: whereas it behooveth to ſay, that
if the Earth ſtandeth ſtill, the ſtone departeth from reſt, and
ſcendeth perpendicularly; but if the Earth do move, the ſtone

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