210 Wisconsin Academy of Sciences, Arts and Letters. 



Form points A„, a, and b„, draw ordinates to diameter B, B,. These 

 ordinates intersect diameter B, B, in a common point g, and C a g is an 



B* 



elliptic angle, a g=B, cos $■, A,, g=A, cos S; and b,, g=-T-^ cos S-. 



Diagram 6. 



The ordinate A„ g being parallel to to A, C (A,), the angle C A^ g is equal 

 to the angle A, C A„ or the angle that A, makes with A„. Also b,, g being 

 parallel to b, C, the angle C b„ g is equal to the angle that b, makes withb„. 



Draw A„ n and h„ m perpendicular to diameter B, B^. Then 90° plus or 

 minus the angle g b„ m or g A„ n (a) equals the angle that A, makes with 

 B,. Draw g d and g f each equal in length to g C, having angles d g C and 

 f g C each equal to angle a. Then from the right angled triangles d A„ g 

 and f b„ g having perpendicular d g equal to f g, : 



tam d A, g : tan f b„ g : : ~ cos 5 : A, cos 3- : : B,^ : A,^ 



.A., 



