SAGR. I do not very well underſtand the queſtion.
SALV. I will expreſs it better by drawing a Figure: therefore
I will ſuppoſe the line A B [in Fig. 3.] parallel to the Horizon,
and upon the point B, I will erect a perpendicular B C; and after
that I adde this ſlaunt line C A. Underſtanding now the line C
A to be an inclining plain exquiſitely poliſhed, and hard, upon
which deſcendeth a ball perfectly round and of very hard matter,
and ſuch another I ſuppoſe freely to deſcend by the perpendicular
C B: will you now confeſs that the impetus of that which
ſcends by the plain C A, being arrived to the point A, may be
equal to the impetus acquired by the other in the point B, after
the deſcent by the perpendicular C
I will ſuppoſe the line A B [in Fig. 3.] parallel to the Horizon,
and upon the point B, I will erect a perpendicular B C; and after
that I adde this ſlaunt line C A. Underſtanding now the line C
A to be an inclining plain exquiſitely poliſhed, and hard, upon
which deſcendeth a ball perfectly round and of very hard matter,
and ſuch another I ſuppoſe freely to deſcend by the perpendicular
C B: will you now confeſs that the impetus of that which
ſcends by the plain C A, being arrived to the point A, may be
equal to the impetus acquired by the other in the point B, after
the deſcent by the perpendicular C
The impetuoſity of
moveables equally
approaching to the
centre, are equal.
moveables equally
approaching to the
centre, are equal.
SAGR. I reſolutely believe ſo: for in effect they have both the
ſame proximity to the centre, and by that, which I have already
granted, their impetuoſities would be equally ſufficient to re-carry
them to the ſame height.
ſame proximity to the centre, and by that, which I have already
granted, their impetuoſities would be equally ſufficient to re-carry
them to the ſame height.
SALV. Tell me now what you believe the ſame ball would do
put upon the Horizontal plane A B?
put upon the Horizontal plane A B?
Vpon an
tall plane the
able lieth ſtill.
tall plane the
able lieth ſtill.
SAGR. It would lie ſtill, the ſaid plane having no declination.
SALV. But on the inclining plane C A it would deſcend, but
with a gentler motion than by the perpendicular C B?
with a gentler motion than by the perpendicular C B?
SAGR. I may confidently anſwer in the affirmative, it
ing to me neceſſary that the motion by the perpendicular C B
ſhould be more ſwift, than by the inclining plane C A; yet
vertheleſs, iſ this be, how can the Cadent by the inclination
rived to the point A, have as much impetus, that is, the ſame
gree of velocity, that the Cadent by the perpendicular ſhall have
in the point B? theſe two Propoſitions ſeem contradictory.
ing to me neceſſary that the motion by the perpendicular C B
ſhould be more ſwift, than by the inclining plane C A; yet
vertheleſs, iſ this be, how can the Cadent by the inclination
rived to the point A, have as much impetus, that is, the ſame
gree of velocity, that the Cadent by the perpendicular ſhall have
in the point B? theſe two Propoſitions ſeem contradictory.
The veloeity by the
inclining plane
qual to the
ty by the
oular, and the
tion by the
dicular ſwifter
than by the
nation.
inclining plane
qual to the
ty by the
oular, and the
tion by the
dicular ſwifter
than by the
nation.
SALV. Then you would think it much more falſe, ſhould I
ſay, that the velocity of the Cadents by the perpendicular, and
inclination, are abſolutely equal: and yet this is a Propoſition
moſt true, as is alſo this that the Cadent moveth more ſwiftly by
the perpendicular, than by the inclination.
ſay, that the velocity of the Cadents by the perpendicular, and
inclination, are abſolutely equal: and yet this is a Propoſition
moſt true, as is alſo this that the Cadent moveth more ſwiftly by
the perpendicular, than by the inclination.
SAGR. Theſe Propoſitions to my ears ſound very harſh: and
I believe to yours Simplicius?
I believe to yours Simplicius?
SIMPL. I have the ſame ſenſe of them.
SALV. I conceit you jeſt with me, pretending not to
hend what you know better than my ſelf: therefore tell me
plicius, when you imagine a moveable more ſwift than
ther, what conceit do you fancy in your mind?
hend what you know better than my ſelf: therefore tell me
plicius, when you imagine a moveable more ſwift than
ther, what conceit do you fancy in your mind?
SIMPL. I fancie one to paſs in the ſame time a greater ſpace
than the other, or to move equal ſpaces, but in leſſer time.
than the other, or to move equal ſpaces, but in leſſer time.
SALV. Very well: and for moveables equally ſwift, what's
your conceit of them?
your conceit of them?
SIMPL. I fancie that they paſs equal ſpaces in equal times.
zoom in
zoom out
zoom area
full page
page width
set mark
remove mark
get reference
digilib