1the ſaid Moveable doth naturally deſcend; whereupon there reſults a
mixture of certain contrary Affections, to wit, that degree of Celerity
acquired in the precedent Deſcent, which would of it ſelf carry the Move
able uniformly in infinitum, and of Natural Propenſion to the Motion of
Deſcent according to that ſame proportion of Acceleration wherewith it
alwaies moveth. So that it will be but reaſonable, if, enquiring what
accidents happen when the Moveable after the Deſcent along any incli
ned Plane is Reflected along ſome riſing Plane, we take that greateſt de
gree acquired in the Deſcent to keep it ſelf perpetually the ſame in the
Aſcending Plane; But that there is ſuperadded to it in the Aſcent the
Natural Inclination downwards, that is the Motion from Reſt Accelerate
according to the received proportion: And leſt this ſhould, perchance, be
ſomewhat intricate to be underſtood, it ſhall be more clearly explained by a
Scheme.
mixture of certain contrary Affections, to wit, that degree of Celerity
acquired in the precedent Deſcent, which would of it ſelf carry the Move
able uniformly in infinitum, and of Natural Propenſion to the Motion of
Deſcent according to that ſame proportion of Acceleration wherewith it
alwaies moveth. So that it will be but reaſonable, if, enquiring what
accidents happen when the Moveable after the Deſcent along any incli
ned Plane is Reflected along ſome riſing Plane, we take that greateſt de
gree acquired in the Deſcent to keep it ſelf perpetually the ſame in the
Aſcending Plane; But that there is ſuperadded to it in the Aſcent the
Natural Inclination downwards, that is the Motion from Reſt Accelerate
according to the received proportion: And leſt this ſhould, perchance, be
ſomewhat intricate to be underſtood, it ſhall be more clearly explained by a
Scheme.
Let the Deſcent therefore be ſuppoſed to be made along the Declining
Plane A B, from which let the Reflex Motion be continued along another
Riſing Plane B C: And in the firſt place let the Planes be equal, and
elevated at equal Angles to the Horizon G H. Now it is manifeſt, that
the Moveable ex quiete in A deſcending along A B acquireth degrees of
Velocity according to the increaſe of its Time, and that the degree in B
is the greateſt of thoſe acquired and by Nature immutably impreſſed, I
mean the Cauſes of new Acceleration or Retardation being removed:
of Acceleration, I ſay, if it ſhould paſſe any farther along the extended
Plane; and of Retardation, whilſt the Reflection is making along the
Acclivity B C: But along the Horizontal Plane G H the Equable Mo
tion according to the de-
120[Figure 120]
gree of Velocity acquired
from A unto B would ex
tend in infinitum. And
ſuch a Velocity would
that be which in a Time
equal to the Time of the
Deſcent along A B would paſſe a Space in double the Horizon to the ſaid
A B. Now let us ſuppoſe the ſame Moveable to be Equably moved with
the ſame degree of Swiftneſſe along the Plane B C, in ſuch ſort that alſo
in this Time equal to the Time of the Deſcent along A B a Space may be
paſſed a long B C extended double to the ſaid A B. And let us under
ſtand that as ſoon as it beginneth to aſcend there naturally befalleth the
ſame that hapneth to it from A along the Plane A B, to wit, a certain
Deſcent ex quiete according to thoſe degrees of Acceleration, by vertue
of which, as it befalleth in A B, it may deſcend as much in the ſame
Time along the Reflected Plane as it doth along A B: It is manifeſt, that
by this ſame Mixture of the Equable Motion of Aſcent, and the Acce
lerate of Deſcent the Moveable may be carried up to the Term C along
the Plane B C according to thoſe degrees of Velocity, which ſhall be
Plane A B, from which let the Reflex Motion be continued along another
Riſing Plane B C: And in the firſt place let the Planes be equal, and
elevated at equal Angles to the Horizon G H. Now it is manifeſt, that
the Moveable ex quiete in A deſcending along A B acquireth degrees of
Velocity according to the increaſe of its Time, and that the degree in B
is the greateſt of thoſe acquired and by Nature immutably impreſſed, I
mean the Cauſes of new Acceleration or Retardation being removed:
of Acceleration, I ſay, if it ſhould paſſe any farther along the extended
Plane; and of Retardation, whilſt the Reflection is making along the
Acclivity B C: But along the Horizontal Plane G H the Equable Mo
tion according to the de-
120[Figure 120]gree of Velocity acquired
from A unto B would ex
tend in infinitum. And
ſuch a Velocity would
that be which in a Time
equal to the Time of the
Deſcent along A B would paſſe a Space in double the Horizon to the ſaid
A B. Now let us ſuppoſe the ſame Moveable to be Equably moved with
the ſame degree of Swiftneſſe along the Plane B C, in ſuch ſort that alſo
in this Time equal to the Time of the Deſcent along A B a Space may be
paſſed a long B C extended double to the ſaid A B. And let us under
ſtand that as ſoon as it beginneth to aſcend there naturally befalleth the
ſame that hapneth to it from A along the Plane A B, to wit, a certain
Deſcent ex quiete according to thoſe degrees of Acceleration, by vertue
of which, as it befalleth in A B, it may deſcend as much in the ſame
Time along the Reflected Plane as it doth along A B: It is manifeſt, that
by this ſame Mixture of the Equable Motion of Aſcent, and the Acce
lerate of Deſcent the Moveable may be carried up to the Term C along
the Plane B C according to thoſe degrees of Velocity, which ſhall be