424 APPENDIX ON DRAWING THE 



Fig. 383. 



Iff! 



But it would frequently be inconvenient, if not 

 impracticable, when several modifications are to 

 be represented on the same crystal, to trace the 

 requisite intersections within the crystal, on account 

 of the minuteness of the secondary planes, and the 

 number and proximity of the lines which must be 

 drawn in order to exhibit them. We may, under 

 such circumstances, resort to a construction, of the 

 character of that exhibited in fig. 383. Let us sup- 

 pose we have to draw a doubly-oblique prism modi- 



