U V w 



W 



u 







THE CURVE ON ONE OF THE COORDINATE PLANES. 483 



As x x vanishes only for particular directions of the system a, /3, y, we must 



assume 



WWW 



or briefly 



Let us form also 

 We have 

 First, 



Applying 



and 



we get 



Secondly, 





V.0- 1 \0-V = ? 7 l 0Vv 



Bfa-fy-H** — ^jjk, &c, 



T0\7- / m \ v ^y 



Hence 



Having 

 we get 



It- tfc 



= i r .(V^'0=^.i) 



U> W 



»» 



Hence 



*(^Kf-t)+< : 



w 



mS^(0- 1 i)=-x o S— J 



