[ 9+5 ] 
fin. ADG = fin.KDG, erit componendo DAxGK 
: G A x D I( ; : fin. D G A : fin. D G K. Quas ratio, 
fi ponatur ut i ad r, erit /.GAxDK = r .GKxDA. 
§ *• 
Incidat radius luminis A G in fuperficiem fphreri- 
cam LG, G 
cujus cen- 
trum eft D, a *xTe *“5 
et refringatur fecundum redum G K, quaeritur con- 
curfus K radii refradi G K cum axe fphaeras A L D, 
poftto arcu LG fatis parvo. 
A pundo incidentias G cadat GE normalis ad 
axem A D, ducaturque radius fphaerae G D. His 
fadis eft per elementa, AG q = AD q -j- D G <7 
— 2 AD x DE = AD^-j-DL^— 2 AD xDL-LE 
— AD ■ — DL^-f iADxLE = AL^/-f 2 AD 
xLE, adeoque AGr=r\/AL^-f- 2 ADxLE = 
(ob LE fatis parvam) AL -f- A E quampro- 
xime. Similiter KG^ = KD^-E-DG^-f aKD x DE 
= KDHDL^2KDxDL-LE=:KDTDL ? 
— 2 D K x L E K L^ — 2 K D x L E, adeoque 
KG = /KL; — 2 K D x LE = KL — ? DxLE 
quamproxime. 
Jam vero eft (§ i .) /. G A x D K = r . G K x D A, 
quare fubfti- CL 
tutis valori- 
busmodoin- K Et; 35 b 
vends ipfarum GA et GK, habetur i.KDx (AL 
X L E \ _ a . /tz t K D x L E' 
AL 
;) = r. A D X (K L - 
KL 
:), et 
tranf- 
