298 



Miss Marian Baxter on the Dispersion 



The wave-lengths of these points having been obtained 

 from the wave-length curve the set of eight curves shown in 

 fig. 1 was then plotted. The parts of the curves which lie 



Fia:. 1. 



4000 Wstse Length. 



Observed values 0. 



Calculated vaiues -\ — \-.] 



between wave-lengths 4046 aiid 4200 are shown on an 

 enlarged scale in fig. 2. 



For photographs 1 and 2 the values of a 1 and a 2 are calcu- 

 lated from summations taken over a wide wave-length range 

 (4058-5600), for the remaining six photographs a shorter 



