560 



Fi?. 1. 



the directions CY and ('Z, wliile n is some integer. If Kz' is 



equally such a zone-axis, then just in the same way —'-=?« — , 



■ CK c 



where m is also an integer. The projected spots ,S' and ,,S", corre- 

 sponding witli the reticukr planes jlUij and \Oll\ of the crystal, 

 are therefore in the directions C'A' and CT of the stereographical 



projection situated in distances from the central spot (', of: 2.4 — 



c 

 . 2^ . lOOa lOü 



and --, or in our case of: and — uim. In the same way for 



c c c • 



spots corresponding with the reticular planes of the symbols \hol\ 



and \on \, these distances from C, become : — . ^-^~, resp —. — mm 



he k c ' ' 



The point of intersection M of both zone-circles, corresponding 

 with the zone-axes K:, resp. Kz' , possessing the symbols [/uü] and 

 [ok\ ], represents the stereographical projection of a spot, corresponding 

 with a plane of the structure with the symbol \/ikl\; etc. In this 

 way it is possible to deteruiine the indices of every spot in the 



