[ XCIII]
How to Draw a Circle in Perspective more Correctly, by Using Sixteen Guiding Points
First draw square ABCD. From O, the middle of the base, draw semicircle AKB, and divide it into eight equal parts. From each division raise perpendiculars to the base, such as 2 O, 3 O, 5 O, &c., and from divisions O, O, O draw lines to point of sight, and where these lines cut the diagonals AC, DB, draw horizontals parallel to base AB. Then through the points thus obtained draw the circle as shown in this figure, which also shows us how the circumference of a circle in perspective may be divided into any number of equal parts.
Fig. 175.
[ XCIV]
How to Divide a Perspective Circle into any Number of Equal Parts
This is simply a repetition of the previous figure as far as its construction is concerned, only in this case we have divided the semicircle into twelve parts and the perspective into twenty-four.