[ 97 2 ] 
diffipatior.es radiorum heterogeneorum circa focot 
i 
conjugatos A et A. Quaeratur earum relatio. 
Quoniam B et B funt foci conjugati radio- 
rum maxime refrangibilium, quorum ratio re- 
fradtionis eft N 4- n ad i, erit ^ 4- = 
1 v a PB 
— ' i 
N-fw — i . - — f- — . Similiter quoniam pundtaC et C 
funt foci conjugati radiorum minime refrangibilium, 
quorum ratio refradtionis eft N — n ad i, erit 
i 
Fc 
+ 
r 
PC 
N — n 4- i . - 4- 7 . Subtrahatur ha:c 
* a 1 b 
pofterior cequatio a priore, et habebitur 
PB 
PC 
-j — -7 — r* = in . - + five conjungendo binos 
PB PC a b 
PC — PB , PC — PB 
terminos : H ; r 
PB x PC 
PBxPC 
' quae 
pro PBxPC etPB x PC, fcribendo P A q et 
i r 
PA v, et pro - + r fcribendo zr=r ~= — , evadit - 2 ^. 
J F a b N X . P PA^r 
= — - - — j- exhibens relationem inter dif- 
N — i . P 
i i 
fipationes conjugatas B C et B C. 
His pracmiffis, intelligantur lentes quotcunque P, P, 
n in 
P, P, &c. quarum diftantiae focorum principalium 
refpedlu radiorum mediocriter refrangibilium fint 
i ii hi 
P, P, P, P, &c. refpcdtive, ordine difpofitas in axe 
earum 
