234 Of the SOLIDS 
1 
der the radius, and an arch A, fuch that’ cof : A 
pL aah ae ©; if A be computed, the attraction 
4colta.cofté. cof + 
ha DN 
In the cafe of a circular plane, our general propofition agrees 
with what SirIs aac NewrTon has demonftrated. IfCFD (Fig. 13.) 
be a circle, BA a line perpendicular to the plane of it from its 
centre B; A, a particle anywhere in that line; the force with 
which A is attracted, in the direction AB, is 29 G-s ane *, 
in which the multiplier 2 7 is fupplied, being left out in the 
inveftigation referred to, where a quantity only proportional 
to the attraction, is required: ‘Now. AD! is the cofine of, the, 
angle BAD, and, theréfore, 1 01 AEB 29 is its ebb fine § and, 
AD 
therefore, if the arch:GEK. be deferibed. FiO the centre. Asi 
with the radius 1, and if the fine, GH, andthe. chord,-EG: be: 
drawn, HE is the -verfed fine: off BAD, and the attraction 
=27EH.. But 2.EH = EG’, becanfe 2 is the diameter of 
the circle GEK ; therefore the attraction = x. EG? = the area 
of the circle of which EG is the radius, or the f{pherical furface) 
included by the’ cone, which hasiA for ‘its Magee and. the 
circle CFD. for its bafe. to : {3 i lev 
XXI. 
* Princip, Lib. i. Prop. go. 
