40 



TERMINOLOGY. 



Fig. 78, exhibits the right square Prism with its lateral edges re- 

 placed by tangent planes. 



Fig. 79, the same, with the terminal edges replaced by tangent 

 planes. 



Fig. 78. f Fig. 79. 



1C 



Fig. 80, the same, with the solid angles replaced by tangent planes. 



In the right rectangular Prism the lateral edges are similar, 

 likewise the solid angles; but the adjoining terminal edges are dis- 

 similar. According to the law of symmetry, therefore, the modifi- 

 cations take place in the following manner. 



Fig. 81 presents the right rectangular Prism with its lateral edges 

 replaced by tangent planes. 



Fig. 80. Fig. 81. 



i P 



ct\ 



JM 



Fig. 82, the same with its solid angles replaced by single scalene 

 triangular planes, which incline on the three adjacent, primary planes 

 at unequal angles. 



Fig. 83, the same, with the lesser terminal edges replaced by 

 single planes. 



Fig. 82. Fig. 83. 



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