20?
In fundo fpeculum quod diximus dfe cavatum,
In medio terebratur , ibique foramine parvo
180$
Panciitur in gyrum : fummo at quod vertice parvum
Huic tunc oppofitum eft molis regione patentis
In media fpeculum , non plana , at fronte cavata e ft,
Et multo magis ipfa cavata e ft, interioris
Quam fpcculi frons fit ; parvi focus interiore
181«
Pnutcrca a fpeculo p lu s , quam fuus ip fc , recedit.
Interiori itidem rima: fubnedlitur alter
A t parvus tubus, intus habet qui non nifi binas
Sic pofitas lentes, minus ut convexa f i t i l l a ,
Q u x propior fpeculo , pauloque tumentior altera , i8 ip
Atque inter fefe fpatio breviore locantur,
Exquirunt quam quod gemina intervalla focorum»
Jamne v ides, quod ite r peragant , qui a corpore vifo
M ittuntur radii ? fubeunt illi agnfinc magno
Os
L I B E R O C T A V U S .
cu lu m f p h x r ic u m c a v u m ,
te
m u l
to m agis c a v u m , q u a m illu d p r i u s :
id a u te m ita a p p l i c a t u r
,
u t d ift e t
a p riore p a u llo p l u s , q u a m p e r
fu m m a m d ifta n tia ru m f o c a l i u m ,
n im ir u m ut e x c ip ia t r a d io s d i g r e f -
f o s ^ a d iftan tia p a u llo m a j o r e ,
q u a m fit ejus fo ca lis d i f t a n t ia :
in fra fo r a m e n p rim i f p c c u li a p -
plicarur tu b u lu s c u m b in is l e n
tibu s c o n v e x i s , q u a r u m c a , q u x
e ft p r o p io r ipfi (p e c u lo , e f t m a
j o r ,
&c
m in u s c o n v e x a : e x b i n x
Jentes d ifta n t a fc in v ic e m m i n u s ,
q u am p ro fu m m a fu a r u m d i f t g n -
tia ru m fo c a liu m ,
J am v e r o radii d ig re d i a b o b j e -
£to , in g r e d iu n tu r p er illa m a p e r
tu ram in g e n te m to ta lem f u m m i
tubi , S rin cu rru n t in fp c c u lu m m a
ju s . A b
illo r e f l e x i ,
te
c o l l c & i
in ejus fo c o , tu m ita d i v e r g e n
tes , u t tam e n a d h u c fatis d c n f i
in cu rra n t in fp e c u lu m m i n u s , rcr
fte<ftuntur a b h o c ad f o r a m e n f p c
culi p r i o r i s , per q u o d t r a d u t t i ,
te
refradti a b in is o c u la r ib u s d o
Jabuntur d e m u m ad o c u lu m . P o r
ro radii d igre fli a q u o v is u n i c o
o b je fti p u n f t o , a q u o r u m d i r o
d tio n c p e n d e t d iftin dH o v i f i o n i s ,
c o e u n t p r im o in fo c o fp c c u li m a
jo ris , ubi p r im o p in g it u r im a g o
o b j c & i : ip fo s ja m in d e d iv e r g e n te s
e x c ip it fp e c u lu m m in u s ,
te
c u m
id p u n d tu m d iv e r g e n t ix d ifte t ab
ip f o m a g i s , q u a m ejus fo c u s ra
d io r u m p a r a lle lo r u m > re d d it cos
c o n v e r g e n te s ad p u n & u m p o fitu m
u ltr a p r im a m
o c u la r e m , q u x
id c ir c o ip fo s c o l l i g i t ,
te
n o v a m
o b j e r i i im a g in e m e ffo r m a t in lo
c o p r o p i o r e , q u a m fit e ju fd e m
le n tis fo cu s r a d io r u m p a r a lle lo
r u m : id p u n d tu m e ft fo c u s ra
d io r u m p a r a lle lo r u m f c c u n d x len
tis , q u x c u m co s radios e x c ip ia t
d iv e r g e n te s a fu o f o c o , re d d it
p a r a llc lo s ,q u o d re q u iritu r a d hoc>
u c a b o cu li h u m o r ib u s r e d d a n tu r
c o n v e r g e n te s ad^ fu n d u m i p f i u s ,
te
in c o i m a g in e m d iftin d ta m
e f f o r m e n e . U t a u te m c o n fu la t u r
d ive rfis o c u lo r u m c o n ft it u t io n i-
b u s , id p r x f t a t u r , u t fp c c u lu m
illu d m in u s re m o v e r i p o ffit a m a
jo r e ,
te
ipfi a d m o v e r i , q u o pa-
£ lo im a p o a p r im a le n te e ffo r -
n ia t u r c i t i u s , vej f e r i u s , a d e o
q u e p r o d e u n t ii radii a fe c u n d a
