ON ABERRATION AT A CURVED SURFACE. 



Ditto by Potter's Formula (second approximation) . 



2»' 1 2 2 \(i) 2 J \ 2 / V 2 / 



. J_ _ 3 a _ 1-23954. 



"17 ~ T y s 



.•. u' = 6*452 inches, 

 but Qq = 5 942, as found above. 

 .-. Error by approximation = -51 inches in excess. 



ARITHMETICAL WORKING. 

 AD = 



•G4279 

 •64279 



»«QA. 





QE 



578511 

 449953 

 128558 

 257116 

 385674 



AD»= -41317S9841 



2-23396 

 QD= 2-23396 



1340376 

 2010564 

 670188 

 670188 

 446792 

 446792 



QD 2 = 4-9905772816 

 AD 2 = -4131789841 



QA 2 = QD 2 + AD a 



5-4037562657(2-32459S 

 4 



43)140 

 129 



462)1137 

 924 



4044)21356 

 18576 



464S5)278026 

 232425 



464909)4560157 

 41S4181 



4649188)37597600 



37193504 



404096 



