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THE BELL SYSTEM TECHNICAL JOURNAL, OCTOBER 1951 



photographs taken before the attempt was made to pole the crystals. 

 Whereas a Laue photograph of a perfect single crystal would show a pat- 

 tern of single spots, crystal a shows a pattern of groups of spots joined by 



Fig. 3 — A. Crystal a after the application of a high field at elevated temperature. 

 Edges at 45° to polarization directions of crossed nicols 



B. Crystal h after application of a high field at elevated temperature. Edges at 45° 

 to polarization directions of crossed nicols. 



Fig. 4 — A. Same as Fig. 3A, but at extinction position. 

 B. Same as Fig. 3B, but at extinction position. 



fainter streaks and crystal b shows a pattern of short streaks. In both cases, 

 the streaks indicate crystal material of continuously varying orientation, 

 but in the case of crystal a it is transitional in orientation between two or 



