( 99 ) 
Sit > / + = / & ~rr ^ Et fi velocttas corporis 
fit ea quas ab infinite cadendo acquiritur, erit f 
A X v> ~ 1 
b z 
A X 
i * — i 
feu p~ — - — • 
At fi velocitas major fit aut minor hac velocitatc, fist uti 
e 2 = 
fT P 1 V Tn '~ 1 
Unde 
rV 
/ 4 z -L 
oftenfum eft _ 
zp z m — i x m ~’ 1 
P ro?/ 4 & ponendo carum valores £ e z & b z c z , erir 
m — i 
4V **«’ + «**—,. <■* — 
— — — feu — = , & net p = 
f x m ~ l p a ;-- 1 
a z x m ~ l 
b z 4“ 
x 
f»— !*• 
Adeoque fi Vis centripeta fit reciproce ut cubus diftantiar. 
a 1 x z 
hoc eft, fi fit m = 3 8tm — 1 — *• Erie p z — , vef/> 1 
0 
a~ X 1 
^ >vdd ^ ue ? . = __, 
Tn primocafu conftat Gurvam efle Spiralem Logarithmicam : 
ax 
nam fit p = ~~ 18c b: a : : x : p. adeoque ob conftantem ra- 
b 
tionem b ad a, erit angulus C IP ubique conftans. 
a z x z 
Fonamus jam efle f — & cx hac fuppofitione tres 
oriuntur diverfae Curvarum fpecies, prout a major eft quam b 9 
aut ei cequalis, aut minor. Fig. HI. 
Et primo fit a major quam b. Centro C & ad diftantiam 
quamvis datam defcribatur circulus HT X, cui re&xC ft, Cl 
produ&ae occurrant in T &X. Et eft IN 1 : K :: I ? z : P C z 
F & ita 
