432 



APPENDIX 



-ON DRAWING THE 



directing planes 1234, and 1654, be taken to re- 

 present two planes w, their intersection will be the 

 line 1 4, bisecting the axis at o. 



Having drawn the edges of the planes m on the 

 primary planes in fig. 386, we may find their inter- 

 sections with o and o'. by taking a' b', on the vertical 

 edges of o, equal to the portion a b of the ajtis, cut 

 off by the terminal edges of the planes m, and join- 

 ;': : c //, c' b'. 



Fig. 388. 



X? / 



Our next step should be to add the planes/?. As 

 wo shall have subsequently to add the planes ', it is 

 not strictly necessary to find any other intersections 

 of the plane/?, than those which correspond toff, 

 fig. 388, J\o.2. But for the sake of an additional 

 illustration, we shall find the intersections of/;, with 

 /, and their adjacent intersection with each other. 



