272 



Mr. A. S. Percival : Method of 

 ■Fig. 8.; 

 H 





/m 







» N. 



/ "^ — — "" 



^^\ » 











-. 



^"*~"*~"~-»^ ^"""^-O 







- V* ^""^^s^ 





H" 



C 



* 

 * 



c 



Eef raction of a plane wave-front by a planoconvex lens. 



1-523 



0i- 



*i' 



/?i- 2 - 



* 2 '. 



P t P 2 . 







30° 



41° 2' 28" 



60° 







19° 9' 56" 

 25° 32' 20" 

 34° 39 r 17" 



-14-5602 ; 

 -11-8685 |-10° 50' 4" -16° 38' 9" 

 -10-0001 -15° 30' 8"|-24° 1' 13" 

 -6-8447 I -25° 20' 43"! -40° 41' 20" 



3 



-2-3724 

 -1-8380 

 - -5532 



/P 2 . 



Pt> 



v. 



i°- 



-11-5602 

 -9-4961 

 -8-1621 

 -62915 







1-7103 

 1-9925 

 2-0421 



-7-5904 

 - 5-9337 

 -4-8151 

 -2-9081 





 -3-1366 

 -3-9438 

 -5-2245 



The geometry of fig. 9 shows that 



(i.) sin 'CiPiS = — l sin C^SPx, or sin <f>i= - sin 6 X ; 



(ii.) C 2 N = M , G 1 -MC 1 = C 1 C 2 sinC 1 C 2 M'-C I P 1 sinC l P 1 M, 

 and as C 1 C 2 M' = C 2 TP 1 =^ 1 -^) 1 4-^/ ? 



r 2 sin ^ 2 = (r 1 -\-t — r 2 ) sin (0 l — $\ + <f>i) — n sin 9/ ; 



(iii.) P^sBinCsTPsrrCaPjsinLCjPs-CiPrsinSdP! : 

 or P X P 2 sin (<9 : - fa + £/) = r 2 sin (4> 2 + X - fc + 0/) 



— r!sin((9, — </>!) ; 



