THEORY OF POLYCONIC PROJECTIONS. 



55 



on 



and q^ 

 f'q^ as 



in the line of 

 diameter 



^ 



measures. A circle constructed 

 is the required projection, since 



q; is the projection of the diameter of the circle on the 

 e of measures. This circle can be determined in another 

 way by locating 'p and f' as before; then at 'p draw the 



Fig. 17.— Projection of circle whose pole projection lies on the primitive circle on stereo* 

 graphic projection. 



tangent pQ meeting OP produced at Q; then WQ locates 

 C the center of the required circle. With C as center and 

 with Cp' as the radius, we can construct the circle. If P' 

 lies on the primitive circle, P and P' will coincide, and the 

 construction is evident from figure 17. 



