125 



Radius faciel anterioris Lentis .P', . , 



I/ P' P 



== >.' _L ' _i_ 7T> **/' P osterloris = <7 - ; - ',7, TT/ 

 h + x + p.(h - k) k - x - p . (h - k) 



Et his continetur constructio vitri duplicis, radios inciden- 



tes axi parallelos colligentis in foco sine aberratione. 



\ 



Nota, Si distantiae focales et radii facierum per for- 

 mulas . 4. 5, 6. 7, computali prodeunt positivi, designant 

 Lentes et facies convexas^ si negativi, concavas. 

 ^ I'-Vjia,', 



^C"ii .i 



-. &. Si per C et F intelligantur species vitrorum 

 Crown -Glass et Flint -Glass dictorum, et statualur secun- 



duin Dollondum, N = t .S3, N' = 1.58, et -- = , erit 

 riw* 



H ------- 



- i 



xF e.74'38 



P = -- = - (i . jyo^ - - J x P. Item 



WJ -p I 



3 ? ttl I rjriii'jrir.) ( r. 



/" =s 4.5567$; g = 2.3*719; h =a i.66ou; k =: 0.226 ft. 

 f = ^.^y<fj;g'= z.zfygz; h' = 7.51274; ^' = 0.14140, 

 & aequatio definiens relationem Indicum 5; Sc ': 

 VOL. vni^w^ 17; 



