|Galilei, Galileo Dialogues on two world systems 1661, tr. Salusbury, Thomas|
ments, and rea
sons against the
cause of the moti
on of projects, as
signed by Aristotle.
SALV. And was you so credulous, as to suffer your self to be
perswaded to believe these fopperies, so long as you had your
senses about you to confute them, and to understand the
truth thereof? Therefore tell me, that great stone, and that
Canon bullet, which but onely laid upon a table, did continue
immoveable against the most impetuous winds, according as you a
little before did affirm, if it had been a ball of cork or other light
stuffe, think you that the wind would have removed it from its
SIMP. Yes, and I am assured that it would have blown it
quite away, and with so much more velocity, by how much the
matter was lighter, for upon this reason we see the clouds to be
transported with a velocity equal to that of the wind that drives
SALV. And what is the Wind?
SIMP. The Wind is defined to be nothing else but air moved.
SALV. Then the moved air doth carry light things more
swiftly, and to a greater distance, then it doth heavy.
SIMP. Yes certainly.
SALV. But if you were to throw with your arm a stone, and a
lock of cotton wool, which would move swistest and farthest?
SIMP. The stone by much; nay the wool would fall at my
SALV. But, if that which moveth the projected substance, af
ter it is delivered from the hand, be no other than the air moved
by the arm, and the moved air do more easily bear away light
than grave matters, how cometh it that the project of wool flieth
not farther, and swifter than that of stone? Certainly it argu
eth that the stone hath some other impulse besides the motion of
the air. Furthermore, if two strings of equal length did hang
at yonder beam, and at the end of one there was fastened a bul
let of lead, and a ball of cotton wool at the other, and both
were carried to an equal distance from the perpendicular, and
then let go; it is not to be doubted, but that both the one and
the other would move towards the perpendicular, and that being
carried by their own impetus, they would go a certain space be
yond it, and afterwards return thither again. But which of these
two pendent Globes do you think, would continue longest in mo
tion, before that it would come to rest in its perpendicularity?
SIMP. The ball of lead would swing to and again many times,
and that of wool but two or three at the most.
SALV. So that that impetus and that mobility whatsoever is
the cause thereof, would conserve its self longer in grave sub
stances, than light; I proceed now to another particular, and de
mand of you, why the air doth not carry away that Lemon
which is upon that same Table?