( 7^3 ) 
a^ignli rcfra^i, Linde conftat ratio qaam qu^rinius 
Hiiji^i rei cape Exemplum. In Cuttula olei Terebin- 
thina^ oblcrvatur diftantia Iridis Frimari^ ab Oppofico 
Solis 25^:40', quatitur ratio reiraaxonis. 
c Tang: 12'^ , 5.0' = 0,2278063 
f= Secant; ejafdcia== i.oi^^i^j 
ti; l = 0^01182217 
f—r in 211=0,01167265 
DiffiCubrminor 0,00014952. . 0,0550775; 
Summa 0,02549482 
4trr 0,91122525 
Cubus major 0,93472007 o, (^^j-j^^S 
to, 2278063; 
T= Tang-Incid. 5I0 .32' r, 2586322 
iT= Tang. Refr: 52 . 11. o, 6293161 
Denique ut T T -j- 4 ad V T T -j— i :: ita r ad^ 
sw ita I ad ,68026. Quse quidem ratio proxime ac- 
cedit ad illam, quam in Vitro ac plurimis Solidis pdlu* 
cidis experimento inelle conftat. Adarnas aiitem noa 
tantutn duritie ac pretio Diaphana omnia pr.Tcellit, fed 
etiam hac vi Refradiva 5 ciim fit ratio ejus ut 5 ad 2^ 
proxime, vel reftius ut 100 ad 41, Sed de his fortaf- 
fe fuo loco uberius. 
Dum in his fcribendis occupatus tenerer,meohortata 
peritiffimus Geometra Dominus^^eM<?/Vefimilem sequa- 
tionem pro inveftiganda ratione e data Iridis Secunda* 
rise femidiametro inquifivit ^ qua quidem paulo aceurati- 
us determinatur ratio, fed cum Biquadratica fit, pari fa* 
cilitate fi^lculus rion abfolvitur: H^c autem eft 
