330 Prof. W. L. Bragg and Messrs. James and Bosanquet : 

 Taking 



5*30 x 10 17 , 



e =4-77x10- 



/i=10-7 : 



2 \2-81xl0- 8 /' 



c =3xl0 10 , X = 0-615xl0- s , 



B = 4'12, 



this reduces to 



F = 2143./^'a/ sin2 f - 



V I V 1 + cos 2 2^ 



: + 2-06sin2< 



The dotted curves in fig. 2 represent one-half the sum 

 of the ordinates, and one-half the difference between the 

 ordinates, of the upper and lower curves. From these 



Fia\ 4. 



Sin 6 

 Values of F for Sodium. 

 The small circles indicate the observed values. 



dotted curves the absolute value of F a for chlorine, and 

 F^a for sodium, can be calculated directly. They are 

 tabulated below, and the values are plotted against sin 6 

 in figs. 4 and 5. 



