410 



APPENDIX ON DRAWING THE 



To draw a Right Oblique-angled Prism, 

 Fig. 372. 



The right oblique-angled prism may he drawn in a 

 similar manner, keeping the diagonal a b horizontal, 

 and making the angle a d , and the ratios of the 

 edges d a, d 6, and g m y such as they are found in the 

 prism of which we propose to give the figure. 

 ' The oblique rhombic prism may be drawn in a man- 

 ner similar to the two preceding prisms, but it should 

 have a little more elevation given to the back of the 

 figure, in order to render the character of obliquity 

 of the prism more conspicuous. 



From the necessity of elevating the back of right 

 prisms for the purpose of shewing the terminal plane, 

 it is apparent that the character of obliquity cannot 

 be conferred on a figure so drawn, otherwise than 

 by elevating the back of it rather more than that of 

 the right prism. 



To draw the Doubly-oblique Prism. 

 The double obliquity given to the figure of this 

 primary form in the tables of modifications, is too 

 slight to convey an accurate notion of its general 



