ET Rercuxus Maris. 207 
quà particula D urgetur versüs fruftum planis DIN D, 
Dr RD terminatum. 
Sint enim Vn N'n' duæ ordinatæ ex interiori Ellipfi ad 
Axem D d; fint(a) PM, Pm, P M & P m'refpettivè pa- 
rallelæ re&is D N, Dn, D N'& D »'; fint porro plana 
DNR,DNR,Dnr,Dnr,PMZ,PMZ,Pmz, 
P m2 plano PLIB perpendicularia quæ alteri plano, PzZIT 
occurrantinreétis D R, D R, Dr, Dr,PZ,PZ,Pz,Pz, 
refpe@tivè. His pofitis, quoniam Anguli N DN & MP M, 
n Dr & m P m' ponuntur femper æquales ; & reëtæ 
PM&DN, Pmé& Dn, xqualiter femper inclinantur ad 
P 1 communem planorum Seétionem; fi Angulus V D N° 
& inclinatio planorum P b TB , P Z'IT adfeinvicem con- 
tinuo minui fupponantur donec evanefcant , erunt gravita- 
tes particulæ D , in Pyramides DNN'RK'R,Dnnrr& 
particulæ P in Pyramides PM M Z'Z, Pmm'z zultimo 
in ratione reétarum D N,Dn, P M & Pm refpettivè per 
Lemma 3. Eædemque vires fecundüm reétas Axi 4, per- 
pendiculares æftimatæ erunt ut re&æ D, Dv,P0,P3q 
refpeétivè, Unde cùm P O0 F P 4 = 2 D V per Corol. 4. 
Lem. 1. fequitur vim quà particula P urgetur versüs Axem 
A à, gravitate fuâ in Pyramides P MM Z'Z , Pmmzz 
«zqualem effe vi, quà particula D urgetur gravitate fuà ver- 
sùs Pyramides DNNRR, Dnnrr. Quare fi plana 
DNR, P MZ fibi mutud femper parallela & plano 
P bIB perpendicularia moveantur femper circa punéta D 
& P( rectis fcilicet D N, PM os D femper in 
plano P81IB, & re@is DR, Pzin plano PZ IT) erunt 
vires quibus particula P urgetur versùs Axem ex gravitate 
fua in frufta motu planorum P MZ, P m2 fic defcripta, 
æquales femper viribus ,.quibus particula D urgetur versùs 
eundem Axem gravitate fuà in frufta motu planorum D NR, 
D nr defcripta; unde fequitur particulam P urgeri eâdem 
vifecundüm reétam P K, gravitate fuâ in frufla planis PI, 
(a) In bac Figura defcribenda reûtas NR, N'R’, &c. non duximus fecundüna 
régulas perfpedtivæ , fed eà ratione quà facillimè dignofci poffnt, 
