THEORY or POLYCONIC PROJECTIONS. 



49 



mines the point €[ on the Equator, and OF drawn parallel 

 to PP' locates the center at F; with the radius F^ draw 

 the arc 0(iA; this arc is the projection of the Equator. 



Fig. 12.— Construction of parallels on stereographic horizon projection. 



In a similar manner the projections of any desired parallels 

 can be drawn. It is evident that any two of the points 5', 

 c', and D' wiU be sufficient to determine the circle, since 



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