THEORY OF POLYCONIC PROJECTIONS. 



By substituting these values, we obtain 



77 



cos ip du _ n 

 vF^ Zp~~2 



du —n dip 



W 



1 2 cos (p 



1/ du du \ n 



dip 



sm I t: 



1/ du du \ n 



2sin(| + |)cosQ + |) 



sin ( j+|) cos 



"7 ^ "<^ i 



or 



du du 



= n 





COS 



sin 



u+1 u— 1 

 By integration 



loge ^ITl =^ L^Oge sin (1 + -loge COS (| + 1) J +Ioge ^r 



loge h being the constant of integration. Passing ta 

 exponentials we obtain 



u + 1 

 u-1 



= lc tan' 



•(M) 



