Triode Generator ivith Two Degrees of Freedom. 717 



how originally both vibrations build up simultaneously but 

 also that the initial rate of increase of b 2 is smaller than that 

 of a 2 . Further, as follows directly from (9), l> 2 reaches its 



Fiir. 6. 



maximum when b 2 = b 2 — 2a 2 . and thereupon it goes back 

 asymptotically to zero while a 2 increases up to a 2 , its 

 stationary value. 



Summing up, our results can be described in short with 

 the aid of the schematic fig. 7. Mode I. is stable for 



H 



Fiff- 7. 



B 



MODE II 

 MODE I 



CO 



"i 



o) 2 2 < <* 2 (AB), Mode II. for co 2 2 > a* (EF). Mode I. is 

 metastable for a> 2 2 >a> 1 2 but only up 1o the point C (BC) ; 

 Mode II. is metastable for w 2 2 > Wl 2 up to the point G (FGr). 

 The part CD is unstable for Mode L, and the part GH for 

 Mode II. DK represents the part where Mode I. is 



