THEORY OF COMPOUND CURVES IN FIELD ENGINEERING 1 45 



of one of the pencils with the normal pencil of the other, i. e., consists of 

 two circles which both pass through M and O, which also follows as a 

 special case of the theorem under 2. 



or 



Fig. 3 



The equation of the line V t is 



xk + y — ak — b — o, 



xk y ak + b 



+ 



1 7 1 + k 2 i 1 + k 2 V 1 + k'- 



o, 



