Archimedes Texts

196
Power, or by some Angel, a very great Cannon bullet were carri
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 pro
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-----.

A Cannon bul
let would spend
more than six days
in falling from the
Concave of the
Moon to the cen
tre of the Earth,
according to the o
pinion of that mo
dern Author of the
Conclusions.

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 suffi
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 thou
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
dayes?

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 lit
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 con
fident that if the question had not required some ingenuity in
working it, you would never have applied your minde unto
it.