H. HAGA AND F. M. JAEGER. ON THE SYMMETRY OF THE RöNTGEN-PATTERNS 



OF TRIGONAL AND HEXAGONAL CRYSTALS, AND ON NORMAL AND ABNORMAL 



DIFFRACTION-IMAOES OF BIREFRINGENT CRYSTALS IN GENERAL. 



Fig. 12. 

 Apatite. Plate parallel to (loTo). 



# 



Fig. 13. 



Quarz. Plate parallel to (r2r0). 



(Normal Pattern). 



Fig. /•/. 



Quarz. Plate parallel to (T2T0). 



(Abnormal Pattern). 



Proceedings of the Acad, of Sciences, Amsterdam, Vul. XVIII. A" 1915/1916. 



