BASE. AND ITS MODIFICATIONS. 131 



' , 



Class e. Solid angles of the base replaced by tan- 

 gent planes. 



This modification would produce only four sides of 

 a prism. 



Class/. Solid angles of the base replaced by two 

 planes resting on the edges of the summits. 



This modification would produce a series of octa- 

 hedrons more acute than the primary. 



Class g. Solid angles of the base replaced by two 

 planes resting on the edges of the base. 



n 2 



