952 



THE BELL SYSTEM TECHNICAL JOURNAL, OCTOBER 1951 



shadowgraph of the reciprocal lattice, illuminated by a point source of 

 light at the origin, as indicated by the dashed lines in Figs. 8A and 8B. 



TWINNING 

 PLANE "^ 



NORMAL TO 

 TWINNING PLANE 



Fig. 7 — Diagram of zonal relations between the two parts of a twinned crystal, 

 o 





y ////I r ! 

 // //ri 6 I 



<W- C^-^-d—^ 



• 



/ / / / > \\ 



/ / / I 



FILM 



/ / / / / 



/ / / 



/ / / / ; 



an 



1 1 



■UJ- 



(a] 



(b) 



Fig. 8 — A. Section of the reciprocal lattice of a twinned crystal and its Laue photo- 

 graph. 



B. Section of the reciprocal lattice of a strained crystal and its Laue photograph. 



From these figures the second point of difference between Laue photo- 

 graphs 5A and 5B becomes clear, namely, that in the case of the bent 

 crystal viewed normal to the bending axis the streaks appear rather uni- 

 form in length, whereas the streaks from the inter-twin oriented material 



