12 



S. L. Penfield — Stereographic Projection. 



will span the distance from 0° to 36° on scale No. 2, figure 3 y 

 find the center point on the diameter x y, and draw the small 

 circle, which will intersect the divided circle at 36° from p. 

 Owing to the character of the stereographic projection, the 

 greater part of projected vertical circles will always lie outside 

 the divided circle. 



6, A and B. 



N 



6 



\36° 





^yc A ^ 



\a' 



^90° L 



"ff\^ \ 







a 





^< A 



Vertical circles nearly 90° from p have very long radii, and 

 are best constructed by means of the curved ruler described 

 later on. Thus, a vertical circle 83° from p, figure 6, B, 

 must pass through two points 83° from p on the divided circle, 



