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

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1Power, or by ſome Angel, a very great Cannon bullet were
ed up thither, and placed in our Zenith or vertical point, and from
thence let go at liberty, it is in his, and alſo in my opinion, a moſt
incredible thing that it, in deſcending downwards, ſhould all the
way maintain it ſelf in our vertical line, continuing to turn round
with the Earth, about its centre, for ſo many dayes, deſcribing
under the Equinoctial a Spiral line in the plain of the great circle
it ſelf: and under other Parallels, Spiral lines about Cones, and
under the Poles falling by a ſimple right line.
He, in the next
place, ſtabliſheth and confirmeth this great improbability by
ving, in the way of interrogations, many difficulties impoſſible to
be removed by the followers of Copernicus; and they are, if I do
well remember-----.
The firſt
ction of the
dern Author of
the little tract of
A Cannon
let would ſpend
more than ſix days
in falling from the
Concave of the
Moon to the
tre of the Earth,
according to the
pinion of that
dern Author of the
SALV. Take up a little, good Simplicius, and do not load me
with ſo many novelties at once: I have but a bad memory, and
therefore I muſt not go too faſt.
And in regard it cometh into
my minde, that I once undertook to calculate how long time ſuch a
grave body falling from the concave of the Moon, would be in
paſſing to the centre of the Earth, and that I think I remember
that the time would not be ſo long; it would be fit that you ſhew
us by what rule this Author made his calculation.
SIMP. He hath done it by proving his intent à fortiori, a
cient advantage for his adverſaries, ſuppoſing that the velocity of
the body falling along the vertical line, towards the centre of the
Earth, were equal to the velocity of its circular motion, which it
made in the grand circle of the concave of the Lunar Orb.
Which by equation would come to paſſe in an hour, twelve
ſand ſix hundred German miles, a thing which indeed ſavours of
impoſſibility: Yet nevertheleſſe, to ſhew his abundant caution,
and to give all advantages to his adverſaries, he ſuppoſeth it for
true, and concludeth, that the time oſ the fall ought however to
be more than ſix dayes.
SALV. And is this the ſum of his method? And doth he by
this demonſtration prove the time of the fall to be above ſix
SAGR. Me thinks that he hath behaved himſelf too modeſtly,
for that having it in the power of his will to give what velocity he
pleaſed to ſuch a deſcending body, and might aſwell have made it
ſix moneths, nay, ſix years in falling to the Earth, he is content
with ſix dayes.
But, good Salviatus, ſharpen my appetite a
tle, by telling me in what manner you made your computation, in
regard you ſay, that you have heretofore caſt it up: for I am
fident that if the queſtion had not required ſome ingenuity in
working it, you would never have applied your minde unto

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