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

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1Earth, doth not onely follow the courſe of that perſon, but doth
much out go him.
Which Problem is connexed with this, that
the moveable being thrown by the projicient above the plane of
the Horizon, may acquire new velocity, greater by far than that
confer'd upon it by the projicient.
The which effect I have with
admiration obſerved, in looking upon thoſe who uſe the ſport of
tops, which, ſo ſoon as they are ſet out of the hand, are ſeen to
move in the air with a certain velocity, the which they afterwards
much encreaſe at their coming to the ground; and if whipping
them, they rub at any uneven place that makes them skip on high,
they are ſeen to move very ſlowly through the air, and falling
gain to the Earth, they ſtill come to move with a greater velocity:
But that which is yet more ſtrange, I have farther obſerved, that
they not onely turn always more ſwiftly on the ground, than in
the air, but of two ſpaces both upon the Earth, ſometimes a
tion in the ſecond ſpace is more ſwift than in the firſt.
Now what
would Simplicius ſay to this?
Sundry curious
Problems,
ing the motions of
projects.
SIMP. He would ſay in the firſt place, that he had never made
ſuch an obſervation.
Secondly, he would ſay, that he did not
lieve the ſame.
He would ſay again, in the third place, that if
you could aſſure him thereof, and demonſtratively convince him of
the ſame, he would account you a great Dæmon.
SAGR. I hope then that it is one of the Socratick, not infernal
ones.
But that I may make you underſtand this particular, you
muſt know, that if a perſon apprehend not a truth of himſelf, it
is impoſſible that others ſhould make him underſtand it: I may
deed inſtruct you in thoſe things which are neither true nor falſe;
but the true, that is, the neceſſary, namely, ſuch as it is impoſſible
ſhould be otherwiſe, every common capacity either comprehendeth
them of himſelf, or elſe it is impoſſible he ſhould ever know them.
And of this opinion I am confident is Salviatus alſo: and
fore I tell you, that the reaſons of the preſent Problems are known
by you, but it may be, not apprehended.
SIMP. Let us, for the preſent, paſs by that controverſie, and
permit me to plead ignorance of theſe things you ſpeak of, and try
whether you can make me capable of underſtanding theſe
blems.
SAGR. This firſt dependeth upon another, which is, Whence
cometh it, that ſetting a top with the laſh, it runneth farther, and
conſequently with greater force, than when its ſet with the
gers?
SIMP. Ariſtotle alſo makes certain Problems about theſe kinds
of projects.
SALV. He doth ſo; and very ingenious they are:
ly, That, Whence it cometh to paſs that round tops run better than
the ſquare?