68 



II. S. COAST AND GEODETIC SURVEY. 



point of intersection, since the inclination is equal to the 

 angle between the given circles. The method of the 

 problem can, however, be applied to any circles, either 

 great or small. Even with small circles we may draw 

 the projections of the parallel great circles and then deter- 

 mine their inclination with respect to each other by the 



Fig. 27. — Determination of the inclination of the planes of two great circles on 

 stereographic projection. 



radii dravni to the point of intersection. In figure 27 

 let SEN be the projection of a great circle, with C as the 

 center for the arc; also let E'WW^ be the projection of 

 another great circle with C as the center for the arc. 

 The angle between the arcs is then equal to CK"C\ since 

 the angle between the radii is equal to the angle between 

 the tangents, and, the projection being conformal, the 

 angle between the circles is preserved in their representa- 

 tions. Locate the projection of the pole of each of the 

 given great circles; K is the projected pole of the first 

 circle and K' is that of the second circle. A great circle 



