. ( 200^) 
thesi, and the Solids spade by their Canverfion about an 
Axe : In many of which, the Magnitude of the Vngk or 
Solidh ihcWd to be but F//?//, where the Magnitude of the 
refpe&ive Plain (on which they ftand, or by whofe conver- 
fion they be made) h I^/fin/t: and (contrary wife) in Other?, 
the Magnitude of the VvgJe or SoUd to be Irjfinit , where 
that of the P/^i« is but Finit 
He gives alfo General Methods^ How. from the Center of 
Gravity oi a ?lain (or of defcribed in a Plain) whofe 
Magnitude is alfo known 5 to find the Magnitude of the 
Vngles, ^nd Solids made by Converfion thereof about af- 
figned Axes V and, from Thefe^, to find That : with other like 
Proceflei, from- Pfo/»/ to Solids^ and fo onward. He fliews 
, notonly (withy^r^i^i/^/e^/e/J the Solidity 2ind Surface o( the 
Sphere and Cylinder but of x\\<:\r Segments and Portions ^ 
^ cut ofFby a Plairij or any numberof Plains, in what man- 
ner foeveri apd the Center of Gravity of the fiime : moft of 
which (as to the Solidity and Center 6f Gravity) is in like 
manner applicable to the iS*/?/)er^/(:/; ufefui in Gnaging Vcf" 
fels, and otherwife. He fhews particularly 5 that the Sea* 
lene Cylindric^ Surface^ xs to the EreU^ as the Perimeter of am 
Elliffe to that of a Circle, " J'^^^ v^^ 
He fhews the Center of v5t^* all' Arthes of Circles, 
with their StiperfieialUnguh^ and the Surfaces made by the 
Converfion p£ (mh Arches about affigned Axes^ And the 
like, of the SeSors^ Segment s^2ind other Portions of Circles^ 
(which are applicable alfo to thofe of Ellipfes > ) with the 
Vnguts^ and Solids made by fuch Converfion ; and their Cen^ 
iers of Gravity. He doth the like in the Cycloid^ fhewing 
the length of the Ti^re»^, and of the P^r//Vz?/ thereof , with 
then Centers of Gravity^ and their feveral SnperficialVnguls^ 
and Snrfaces^ made by Converfion ^z^d the Centers of Gravity 
of all thefe. As like wife the Magnitude of the Plain, as well 
of the Primary Cycloid^z$o( th^ Secundary, whether f(?/i?^r4- 
Bedox Protra&ed '^ with their feveral Tl^age»// / and of the 
Segments and Portions thofe Plains 5 with their feveral 
Vngnls^ and Solids mnde by their Converfion ( Perfeft 3 or 
Imperfefr J aod the Cenitrs of Gravity of all thefe : Where- 
