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BELL SYSTEM TECHNICAL JOURNAL 



The section is then examined through the ruled window of a matching arm, 

 one of which is shown in use in Fig. 5.18. The section is rotated on the table 

 until the etch-figure seen in the quartz is properly aligned with the Unes on 

 the window. Without moving the sections, the viewing arm is replaced with 

 a marking arm, one of which is shown in place in Fig. 5.16. The section is 



t+x +x t 



LHQ RHQ 



B 



+ x 



IN LHQ MATCHING WINDOW 



MARKING 

 TEMPLATE 



+ 



IN RHO MATCHING WINDOW 



Fig. 5.17 — Etch- figures obtained with the pin-hole oriascope in Z-cut sections; A for a 

 line ground surface and B for a coarse grind. The relation of the etch-figures to the struc- 

 ture orientation of the section is shown in C. 



marked through the template of this arm with the desired axes or cutting 

 directions. 



Figure 5.17A, B shows the etch-figures obtained with the pin-hole oria- 

 scope, on Z-cut sections. Figure 5.17A is for a fine ground surface (600 

 carborundum) while Fig. 5.17B is for a coarse ground surface (100 carborun- 



