Page:An introduction to linear drawing.djvu/51

 ﻿of the circle, and you have a cone. A cone is, in fact, a pyramid whose base is a circle, and not a pol- ygon. Sugar loaves are canes.

The height of a cone is a perpendicular let fall from the top or apex to the base. If this perpendicular fall exactly upon the centre of the base, the cone is upright.

The perspective, by changing the apparent dimensions of bodies, gives to the base of a cone the form of an ellipse. The cone presents no other difficulty than the ellipse.

16. Draw an upright cone. (fig. 10.)

parallel to the base. (fig. 9.)

18. Draw an oblique cylinder. (fig. 11.)

Draw two horizontal lines parallel to each other. Draw two equal circles, of which these shall be diame- ters. Let a right line go from centre to centre, and it will be the axis. Then draw lines from circumference to circumference, and you have a cylinder. A piece of the funnel of a stove is a cylinder. A cylinder is, in fact, a prism whose bases are circles instead of polygons*