Sin & adhuc pundtum tradi u breviore lo c e tu r,
Inter fc radii tumido de corpore vitri
Disjungentur, erit ncc j;un , quo tendere poffint,
Conjungique , focus ; led erit tamen , unde videntur 133$
Diredi effugere , cx alia jam parte receptus:
Certe fictus is eft , diciquc vicarius idem
Poffit propterea , fcu forte precarius , ipfis
Ut quoque de fpcculis non mu lto diximus ante .
Aii ea fi 1 fuerit lens aeque concava u trinque ,
134©
Lumiiuque inter fe parili d ilian tia tradlu
Excipiat * faciet porro mage lata meare
Perpetuo, ut citra focus ille precarius extet ,
Atque cavi didet quantum medium illius orbis •
Hic focus eft itidem medius; venien tia nam fi
13 4$
Lumina latclcan t, magis egredienda v itro
Latefccnt, facientquc focum hunc accedere le n t i.
Paulum accedere fin ad fe ven ien tia fingas ,
Ut tamen a fe cgrcflfa recedant , fit focus ille
A vitro abdu&us nimium > longcque remotus.
1 3 5 0
Jam nunc finge m.ts^is m u lto ad Ic accedere p r im a ,
D ir e *
L I B E R O C T A V U S .
i Sr
accedente in im m e n fu m ad f o
cu m ra d io ru m p a r a lle lo r u m . h i c
recedat in im m e n f u m a b ip fa le n
te , donec illo a b e u n t e in c u m
fo cum , h ic a b e a t in i n f i n i t u m ,
radiis
e m e r g e n t ib u s p a ra lle lis .
Q u o d (i d e m u m p u n d u r n ra d ia n s
adhuc m a g is a cced a t ad le n t e m ,
radii jam p r o d e u n t d i v e r g e n t e s
a q u e d a m f o c o v irtu uii p o fit o c i
tra ip f u m , q u e m h i c , uc fu p r a
in fp c c u lis , a p p e lla t fo c u m fid iu m ,
v icarium , p r e c a r iu m .
1 K u c u fc u ic dc le n tib u s c o n
vexis : q u o d fi lens fu e rit u t r i n -
que x q u e c o n c a v a ,
te
radii in e a m
incidant p a r a lle li axi j h a b e b i t u r
focus v i r t u a i i s , radiis d i v e r g e n
tibus polt c g r c l f u m itid e m a c e n
tro priixix u ip c rfic ie i, q u o d ip ( u m
ut i b i , d eb ee in t e llig i d c v itr is e t
iam , & ra d iis ,p r o q u ib u s ra tio illa
fin uum in in g r e flu fit j a d x ,
nec a ccu rate n t v e r u m , n ifi p r o
radiis axi p r o x i m i s ,
te
n e g l c & a
c r a r t it u d in e l e n t i s . Q u o d fi r a d i i
a d v e n i a n t d iv e r g e n t e s , q u o d N o
ft e r e x p r i m i t p e r v o c e m
la t c fc c r t
,
n a m c o n i r a d io fi a m p l i o r e s
fi
v c la t io r e s fiu n t d i v e r g e n d o
pro»-
d i b u n t a d h u c m a g is d i v e r g e n t e s ,
n i m i r u m a f o c o v i i c u a f i a d h u c
p r o p i o r e ip fi le n ti: fi a u t e m a d v e
n i a n t c o n v e r g e n t e s a d p u u & u r n
q u o d d a m r e m o t u m , p r o d i b u n t d i
v e r g e n t e s a f o c o v irc u a li r e m o t i o r e ,
q u a m fit f o c u s r a d io r u m p a r a lle lo
r u m : fi p u n & u i n c o n v e r g e n d a e a c -
c e d a c a d l e n t e m , fo c u s v ir t u a iis a b
e a r e c e d e t , d o n e c illo r e c id e n t e i n
f o c u m r a d i o r u m p a r a lle lo r u m , h i c
a b e a t in i n f i n i t u m
,te
ra d ii p r o d e a n t
p a r a lle li . D e m u m fi r a d ii a d v e n i
a m a d h u c m a g i s c o n v e r g e n t e s , n i
m i r u m a d p u n & u m le n t i a d h u c
p r o p i u s ; j a m e m e r g e n t c o n v e r g e n
tes a d f o c u m r c a lc tn , q u i c o m a g i s
a c c e d e t ad l e n t e m i p f a m , q u o m a
g is a d ip f a m
a c c e d e t
p u n d t u m
c o u Y c r g e n t i x
praecedentis.
