( $77 )

r\. If we take in the Consideration of the Airs Resistance ; we are thensor each os the (e Equal Progrelsions, to Substitute a Dec rea fing ProgressumGeometrical ; in like mannet (and for the fame Reasons) as in the Line ofProjection. ^ i

2.5. Hence ariscth for the first Moment

vi

for the lecond 1

m

; for the third

-t-

m

1

vi

m

1

Gc. And such is m5 m t

6 'c.

therefore the Descent of a Heavy Body falling by its own VVeight. The se- ^4veral Impulses ot Gravity being suppoled Equal. &c.

a 6. That -is, as E L, E ^ 1 , FH, Gc. in the Lineos Descent, answering _to E L, LM, MN, Gc. in the Line of Projection.

- ay. But though the Progreslions for the Line of Projection, are like toeach of those many in the Line of Descent : it is not to be thence interred,

that therefore-in the one, is equal to - in the other : But in the

nt

i

nt 1

6r.

m

Line of Projection (seppose) -— /, (such a part of the Force Impresied,

and a Celerity answerable : ) in the Line of Descent —* g, (such a part of

m a r

the Impulse of Gravity.)

a 8. Those for the Line of Descent (of the sime Body) are ali equal eachto other: Because g, (the new Impulse of Gravity) in each Moment is lup-posed to be the sime.

2.9. But what is the Proportion of / to g, (that is, of the Force Impres-sed, to the Impulse of Gravity, in each Body) remains to be cnquired byExperiment.

30. This Proportion being found as to one Known Force ; the fame isthence Known as to any other Force (whose Proportion to this is given) inthe lanie Uniform Medium.

31. And this being Known as to one Medium, the sime is thence Knownäs to ahy other Medium , the Proportion of whose Resistance to that of thisis Known.

31. If a Heavy Body be Projected Downward in a Pendiculär Line, it

Defcends therefore at .the rate ——-—, ——, & c . of / (the Imprefled

m m z m 3

Force) increascd by -, —

m m

I

I

m

I

&c.

of g, the Impulse of Gravity : (byare here United.

Vol. I.

Prop. 5. and P. 2.5.) because both Force*

E e ec

33 - If