(^8iO; ) ' 
t^mnendum harum Curvarum privilegiujm, quod in iis . 
omnibus Vis centripeta tendons ad S fit uc aliqua reci- 
proca diftantise dignitas, quse^fimpliciflima eft, & utiliC- . 
iima in Naturse indagine, Virium Centripetarum lex. 
• • n H 
iT.,V. Curvarum quarum i : y .a : r proxime con* 
fiderandajcnic ( qqse Curva quidem improprie dicitur) 
ip(a Linea recfta, exiftence S extra redam. > In hac li- 
Jifa,, obrfimilia crianguia P /» », PBS erit C H B Srz= a & 
S^^r) / : y :.vr : 4. Ex linea reda mechodo diredi a 
nihil nifi pundum B conftrui poteft, Mechodo veto in- v 
versi>' perpendicularium nimirum P L,r pi concurfu. con- 
ftfui 4 >Qceft .Cutva, cujus Index .( fi m fit Index Curvae 
B-P ) sequalis erit — ^ ; nam fi Index Curvse B L fit #, 
eric ac proinde Unde in hoc cafu, 
cum «i£= — I erit & ;^quacio Curvse B L eric 
. ^ . i , i ■ 
5 : r‘ : 4*, quse xquatio eft Parabolse ad Focum. Ex 
hac <onftrue aliam, conftituendo anguJum- L S N=2;L S B 
6 erigendo ,L N normalem in S L occurrentem ipfi SN 
inN..Quoniam vero«w=~ erit & sequatio Cur- 
• • * I RN I 
& B =iBN — LN, ergo 
