416 APPENDIX ON DRAWING THE 



Divide the circumference of this circle into six 

 equal parts, by the points a b c d f /, as in the figure, 

 and draw the lines a d, / 6, g o, e c, within the circle. 

 Draw k I parallel to f b. Draw the oblique lines 

 shewn in the figure, from the several points on the 

 circumference of the circle, and from its centre, to 

 the line k /; and from the several points in that line 

 where it is cut by the oblique lines, raise the per- 

 pendiculars as they appear in the figure. On the 

 middle perpendicular line, take a portion 3' 3', equal 

 to the length we have determined on for the axis of 

 the rhomboid, and after dividing this portion into 

 three equal parts, draw the lines m n : p q^ r s, through 

 the upper point 3, and through the points of division, 

 and parallel to the line k I. 



The oblique lines are to be drawn more or less 

 obliquely, according as we would have the rhomboid 

 appear more or less turned round. To elevate the 

 back of the rhomboid, so as to render a plane trun- 

 cating its terminal solid angles visible, draw d i 

 parallel to e c, and join a i. The line d i is the quan- 

 tity of elevation intended to be given to the solid 

 angle a 1 of the rhomboid; and the lines 12, 3, 4 5. 

 are the proportional quantities which the other solid 

 angles require to be elevated in order to preserve 

 the symmetry of the figure. This imaginary elevation 

 of the back of the figure, is thus produced in the 

 drawing. On the perpendicular lines 4', i 1 , and 

 4', which pass through the line m n, take V a! equal 

 to di\ and 4' jf, 4' b', each equal to the line 4 5. 

 On the perpendiculars, I' and I', which pass through 

 the line p <?, take 1' e, 1' c', each equal to the line 

 1 2. And on the perpendicular 3', which passes 

 through the lines k /, and r s, take 3' 0', and 3' 0", 

 each equal to the line 3 0. From the several points 



