410 

 Consequently, 



Dr. L. Vegard 



Fig. 5. 



% C atoms 

 • H „ 



Thus, if we have 



(15) 



the small prism constructed on the atoms should have 

 exactly the same form as the elementary lattice. Now the 

 approximate values found for the two parameters give 



X =35 and a' = 33°, or the condition (15) is very nearly 



fulfilled. In fact, the difference between ~ and «' is found 

 to be so small that we may equally well satisfy the obser- 

 vation on the supposition that condition (15) is exactly 

 fulfilled, so that we have 



5^=* =0-722. 



a' a 



(16 a) 



It might be of interest to find the ratio c"\a" on the 

 supposition that the C atoms were placed at the corners of a 



