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B L: But the conſidering that this Grave deſcending, and ſuſtained

by the Semidiameters B F and B L is one while leſs, and another

while more conſtrained to paſs along the Circumference C F L, is

no other, than if we ſhould imagine the ſame Circumference

C F L I to be a Superſicies ſo curved, and put under the ſame

Moveable: ſo that bearing it ſelf thereon it were conſtrained to

deſcend along thereby; for if in the one and other manner the

Moveable deſcribeth the ſame Courſe or Way, it will nothing im-

port whether, if ſuſpended at the Center B, it is ſuſtained by the

Semidiameter of the Circle, or elſe, whether that Fulciment being

taken away, it proceed along the Circumference C F L I: So that

we may confidently affirm, that the Grave deſcending downwards

from the point C along the Circumference C F L I, its Moment

of Deſcent in the point C is total and entire, becauſe it is not in

any part ſuſtained by the Circumference: And there is not in that

firſt point C, any indiſpoſition to Motion different from that, which

being at liberty, it would make along the Perpendicular and Con-

tingent Line D C E: But if the Moveable ſhall be placed in the

point F, then its Gravity is in part ſuſtained, and its Moment of

Deſcent is diminiſhed by the Circular Path or Way that is placed

under it, in that proportion wherewith the Line B K is overcome

by B C: But if when the Moveable is in F, at the firſt inſtant of

ſuch its Motion, it be as if it were in the Plane elevated according

to the Contingent Line G F H, for that reaſon the inclination of the

Circumference in the point F differeth not from the inclination of

the Contingent Line F G any more ſave the inſenſible Angle of

the Contact. And in the ſame manner we ſhall find the Moment

of the ſaid Moveable to diminiſh in the point L, as the Line BM

is diminiſhed by B C; ſo that in the Plane contingent to the Circle

in the point L, as for inſtance, according to the Line N L O, the

Moment of Deſcent diminiſheth in the Moveable with the ſame

proportion. If therefore ^{*} upon the Plane HG the Moment of the

Moveable be diminiſhed by the total Impetus which it hath in its

Perpendicular D C E, according to the proportion of the Line K B

to the Line B C, and B F, being by the Solicitude of the Triangles

K B F and K F H the ſame proportion betwixt the Lines K F and

F H, as betwixt the ſaid K B and B F, we will conclude that the

proportion of the entire and abſolute Moment, that the Moveable

hath in the Perpendicular to the Horizon to that which it hath up-

on the Inclined Plane H F, hath the ſame proportion that the

Line H F hath to the Line F K; that is, that the Length of the

Inclined Plane hath to the Perpendicular which ſhall fall from it

unto the Horizon. So that paſſing to a more diſtinct Figure, ſuch

as this here preſent, the Moment of Deſcending which the Move