1ſtrument: which difficulty is more ſenſible in it than in thoſe afore

going, foraſmuch as it hath greater Force.

going, foraſmuch as it hath greater Force.

The LEAVER, Vectis.

I Have deferred to ſpeak of the Leaver until the laſt, in regard

that it is of all Engines for raiſing of Weights, the moſt diffi

cult to be explained.

that it is of all Engines for raiſing of Weights, the moſt diffi

cult to be explained.

Let us ſuppoſe that C H is a Leaver, in ſuch manner ſupported

at the point O, (by means of an Iron Pin that paſſeth thorow it

acroſs, or otherwiſe) that it may turn about on this point O, its

part C deſcribing the Semicircle A B C D E, and its part H the

214[Figure 214]

Semicircle F G H I K; and that

the Weight which we would

raiſe by help of it were in H,

and the Force in C, the Line

C O being ſuppoſed triple of

O H. Then let us conſider that

in the Time whilſt the Force

that moveth this Leaver deſcri

beth the whole Semicircle

A B C D E, and acteth accord

ing to the Line A B C D E, al

though that the Weight deſcri

beth likewiſe the Semicircle

F G H I K, yet it is not raiſed to

the length of this curved Line

F G H I K, but only to that of the Line F O K; inſomuch that the

Proportion that the Force which moveth this Weight ought to

have to its Ponderoſity ought not to be meaſured by that which is

between the two Diameters of theſe Circles, or between their two

Circumferences, as it hath been ſaid above of the Wheel, but ra

ther by that which is betwixt the Circumference of the greater,

and the Diameter of the leſſer. Furthermore let us conſider, that

there is a neceſſity that this Force needeth not to be ſo great, at

ſuch time as it is near to A, or near to E, for the turning of the

Leaver, as then when it is near to B, or to D; nor ſo great when

it is near to B or D, as then when it is near to C: of which the rea

ſon is, that the Weights do there mount leſs: as it is eaſie to un

derſtand, if having ſuppoſed that the Line C O H is parallel to the

Horizon, and that A O F cutteth it at Right Angles, we take the

point G equidiſtant from the points F and H, and the point B equi

diſtant from A and C; and that having drawn G S perpendicular

to F O, we obſerve that the Line F S (which ſheweth how much

the Weight mounteth in the Time that the Force operates along

at the point O, (by means of an Iron Pin that paſſeth thorow it

acroſs, or otherwiſe) that it may turn about on this point O, its

part C deſcribing the Semicircle A B C D E, and its part H the

214[Figure 214]

Semicircle F G H I K; and that

the Weight which we would

raiſe by help of it were in H,

and the Force in C, the Line

C O being ſuppoſed triple of

O H. Then let us conſider that

in the Time whilſt the Force

that moveth this Leaver deſcri

beth the whole Semicircle

A B C D E, and acteth accord

ing to the Line A B C D E, al

though that the Weight deſcri

beth likewiſe the Semicircle

F G H I K, yet it is not raiſed to

the length of this curved Line

F G H I K, but only to that of the Line F O K; inſomuch that the

Proportion that the Force which moveth this Weight ought to

have to its Ponderoſity ought not to be meaſured by that which is

between the two Diameters of theſe Circles, or between their two

Circumferences, as it hath been ſaid above of the Wheel, but ra

ther by that which is betwixt the Circumference of the greater,

and the Diameter of the leſſer. Furthermore let us conſider, that

there is a neceſſity that this Force needeth not to be ſo great, at

ſuch time as it is near to A, or near to E, for the turning of the

Leaver, as then when it is near to B, or to D; nor ſo great when

it is near to B or D, as then when it is near to C: of which the rea

ſon is, that the Weights do there mount leſs: as it is eaſie to un

derſtand, if having ſuppoſed that the Line C O H is parallel to the

Horizon, and that A O F cutteth it at Right Angles, we take the

point G equidiſtant from the points F and H, and the point B equi

diſtant from A and C; and that having drawn G S perpendicular

to F O, we obſerve that the Line F S (which ſheweth how much

the Weight mounteth in the Time that the Force operates along