SEPTEM. LENTIVM. 



^55 



long^tuJinc adipiscamur; lcutcm fccundam bBb iii 

 ipfo foco a lcncis obicdiuae couftituamus , tertianv 

 Ycro cCc' ibi , ■vbi obiedum iu A pofitum pcr 

 lcntcm B Tuam imajincm cflct proiccflurum. Qiia- 

 tuor autcm rcliqu.irum binas D, E antc imagincm' 

 ercdam I podrcmas vcio F et G pone eam coUa- 

 cari fumamus. Habcbimus ergo pro his lentibus : 



B=:-i; Cr.-^,; D-^a^ Ezit^^; Fr^^; G-<\5 



r—q'^i e^''— owi 0^^^--wi ^'''--i^; e^r-u; e^^n-o) 



liincque fcmidiamctcr campi Cj)rrsrEr?w. Ponatur 

 ^^^r=M vt lit Cp— .?Vlu crit 



n^=~oo; n^^zz((7- M)w; n^''^r:+(</+^-M)u) 

 Il////4-(e_i_l_^_M)w; n^ir -(/-{- 2-9 + Mjaj et 

 n^'--(4-^-V-M)o). 



50. His pofitis dctcrminationcs tclcscopii funt 

 fcqueatcs : 



ABrra 



^/// — '^'^ ^^ . 



P — 1 — c d-H.;— M 1 



^//// lil^ "== 



^^-' (i-c)' [q-y[Ad 



Wa 



■ i) e. 



^i^E^CT 



-H'7-M) 



c d (p— ■ — d) M «) 



-./— M Ij-'^-^ {i_cj(,-+-d) (d-(_,j_.M(e- i-+-,j-rt"l 



/> — (,-c\'i-Hd;('-t-^)-/-f-=-'J-t-M il'^'^ — (,_c.;.-+-d;:.-^.)- ('— '-H.;-M)(/T--,-t-M) 



yj c def H g | ^. p c J <■ / (.f — ;) Ma 



/> (.-cX.-Ki)(>-h^,(/-.J- ♦-5-hM^^ ^— (i-c;f,-+-*(;j+.eX;-'; (;-f-:-I+MM-9+M; 



lct GOz::,-!^^. 



51.4 



