1raiſeth it, and cannot be eſtimated ſave wthin a ſmall matter.

Moreover, it is neceſſary to obſerve, that it is nothing but the

redoubling of the Chord, and not the Pulley, that cauſeth this

Force: for if we faſten yet another Pulley towards A, about

which we paſs the Chord A B C H, there will be required no leſs

Force to draw H towards K, and ſo to lift up the Weight E, than

there was before to draw C towards G. But if to theſe two Pul

leys we add yet another towards D, to which we faſten the Weight,

and in which we make the Chord to run or ſlip, juſt as we did in

the firſt, then we ſhall need no more Force to lift up this Weight

of 200 pounds than to lift up 50 pounds without the Pulley: be

cauſe that in drawing four feet of Chord we lift it up but one

foot. And ſo in multiplying of the Pulleys one may raiſe the great

eſt Weights with the leaſt Forces. It is requiſite alſo to obſerve,

that a little more Force is alwaies neceſſary for the raiſing of a

Weight than for the ſuſtaining of it: which is the reaſon why I

have ſpoken here diſtinctly of the one and of the other.

redoubling of the Chord, and not the Pulley, that cauſeth this

Force: for if we faſten yet another Pulley towards A, about

which we paſs the Chord A B C H, there will be required no leſs

Force to draw H towards K, and ſo to lift up the Weight E, than

there was before to draw C towards G. But if to theſe two Pul

leys we add yet another towards D, to which we faſten the Weight,

and in which we make the Chord to run or ſlip, juſt as we did in

the firſt, then we ſhall need no more Force to lift up this Weight

of 200 pounds than to lift up 50 pounds without the Pulley: be

cauſe that in drawing four feet of Chord we lift it up but one

foot. And ſo in multiplying of the Pulleys one may raiſe the great

eſt Weights with the leaſt Forces. It is requiſite alſo to obſerve,

that a little more Force is alwaies neceſſary for the raiſing of a

Weight than for the ſuſtaining of it: which is the reaſon why I

have ſpoken here diſtinctly of the one and of the other.

The Inclined PLANE.

If not having more Force than ſufficeth to raiſe 100 pounds, one

would nevertheleſs raiſe this Body F, that weigheth 200 pounds,

to the height of the Line B A, there needs no more but to draw

or rowl it along the Inclined Plane C A, which I ſuppoſe to be

twice as long as the Line

210[Figure 210]

A B, for by this means,

for to make it arrive at

the point A, we muſt

there employ the Force

that is neceſſary for the

raiſing 100 pounds twice

as high, and the more inclined this Plane ſhall be made, ſo much

the leſs Force ſhall there need to raiſe the Weight F. But yet there

is to be rebated from this Calculation the difficulty that there is

in moving the Body F, along the Plane A C, if that Plane were

laid down upon the Line B C, all the parts of which I ſuppoſe to

be equidiſtant from the Center of the Earth.

would nevertheleſs raiſe this Body F, that weigheth 200 pounds,

to the height of the Line B A, there needs no more but to draw

or rowl it along the Inclined Plane C A, which I ſuppoſe to be

twice as long as the Line

210[Figure 210]

A B, for by this means,

for to make it arrive at

the point A, we muſt

there employ the Force

that is neceſſary for the

raiſing 100 pounds twice

as high, and the more inclined this Plane ſhall be made, ſo much

the leſs Force ſhall there need to raiſe the Weight F. But yet there

is to be rebated from this Calculation the difficulty that there is

in moving the Body F, along the Plane A C, if that Plane were

laid down upon the Line B C, all the parts of which I ſuppoſe to

be equidiſtant from the Center of the Earth.

It is true, that this impediment being ſo much leſs as the Plane is

more united, more hard, more even, and more polite; it cannot

likewiſe be eſtimated but by gueſs, and it is not very conſide

rable.

more united, more hard, more even, and more polite; it cannot

likewiſe be eſtimated but by gueſs, and it is not very conſide

rable.

We need not neither much to regard that the Line B C being a

part of a Circle that hath the ſame Center with the Earth, the

Plane A C ought to be (though but very little) curved, and to

have the Figure of part of a Spiral, deſcribed between two Circles,

part of a Circle that hath the ſame Center with the Earth, the

Plane A C ought to be (though but very little) curved, and to

have the Figure of part of a Spiral, deſcribed between two Circles,