Or we may adopt the method shown at Fig. 180, by taking quarter base of both outer and inner square, and finding the measurement mn on each side of C, &c.
Fig. 180.
[ XCVI]
The Angle of the Diameter of the Circle in Angular and Parallel Perspective
The circle, whether in angular or parallel perspective, is always an ellipse. In angular perspective the angle of the circle's diameter varies in accordance with the angle of the square in which it is placed, as in Fig. 181, cc is the diameter of the circle and ee the diameter of the ellipse. In parallel perspective the diameter of the circle always remains horizontal, although the long diameter of the ellipse varies in inclination according to the distance it is from the point of sight, as shown in Fig. 182, in which the third circle is much elongated and distorted, owing to its being outside the angle of vision.
