zSO 



DE TELESCOPIIS 



vndc fit r/=3-a(^-M). Statimtur crgo q-{i-^n)l\l 

 vt fit a'— 3— a;;M, ct formulae noftrac abibunt in 

 has ; 



ABzra 



<-« -pk c dx 



^ *-' — 1 — c" n ( I — n Ai 



C^ 



/// c(j — aiM) M« 



P I _ c • 3— nM 



#.///// 



( I — n Al) 



c '4 — :nM ^*^ (,_c);t_2aM)- 3 — n k 



c(j-2.nM) Ma y? t? c(! — inM) M a 



*;//// — -_w^^ 



/' — (i-cX+-jnM)* 3-1M 



I —'7 



cum ergo fit M=:&!r=^-r^ erit 



; co 



ET-> C(! in.1 J M g 

 '^ — (i.c)u-2nM)' 3 — iM 



et fcmidiamcter campi apparentis (^~ 



41. ExempL I. Sit multiplicatio w— lo , ac 

 fumatur 7i—i ct f~a, tum vcro fit lcntis obic(fli- 

 vac diftantia foci amddig. crit crgo Mn^, ^rrj 

 et (J) — ^ fcu cp — 3°, 35^ et mcnfurac pro tdcsco- 

 pio conftrucndo crnnt 



ABm5 

 BC= 8 

 CDrz 6} 

 DE= I.V 

 EFzi: ItV 

 AF=:3^.V 



Hic ergo tubus circitcr 33 dig. longns ohic(^a in 

 ratione dccupla multiplicabit , campnni antcm ape- 

 rict , cuins diamctcr 2.I vicibus ma or cft quam in 

 tubis confiictis alhonomicis. 



4-2. Ex' 



p' — 5\ dig. 



;y"" = i,V 



FO— '^""' 



