18/7.] Refractive Indices of Glass. 295 



should be perfectly achromatic with a flint. The determinations were 

 made on two angles ; density =2' 55255. 



«=O550466. 6=1-5044. c=-093. 





B. 



C. 



D. 



E. 



b. 



F. 



Most probable value of \i 



1-539155 

 1-539152 



1-540255 

 1-540249 



1-543249 

 1-543236 



1-547088 

 1-547074 



1-547852 

 1-547839 



1-550471 

 1-550466 



Mean of observed values 



1-539157 



1-540253 



1-543248 



1-547088 



1-547852 



1-550471 







(G.) G. 



h. 



H r 







Most probable value of fi 



1-556386 ! 1-556830 



1 



1-556407 1-556852 



1-559999 

 1-560015 



1-562392 

 1-562388 



Mean of observed values 



1-556394 



1 -556825 



1-559998 



1-562392 



Extra Light Flint Glass. — Determinations made from three angles, 

 density=2-86636. 



«=0-549123. 6=1-7064. c= -0-198. 





A. 



B. 



1 



C. D. 



E. 



b. 



Most probable value of jj. 





1-536450 

 1-536448 



1-537673 1-541011 

 1-537663 1540993 



1-545306 

 1-545296 



1-546166 

 1-546158 



Mean of observed values 



1-534067 



1-536450 



1-537682 1-541022 



1-545295 



1-546169 



1 



1 R 



I 



(G.) | G. 



h. H r 





Most probable value of [x 1 549 121 



1-555863 1-556372 



1-560010 1-562760 







1-555881 1-556390 



1-560026 1-562760 





Mean of observed values 1-549125 



1-555870 1-556375 



1-559992 1-562760 



1 





