318 G. p. BIDDER 



Therefore from (2) and (3) 



p'f^^p.Fq, (4) 



= P-'LFx''v. 

 4 



y-^j,l.^.x^v = 2-' (5) 



Z p p 



If I be the length of the oscular jet, I tind by experiment 

 (p. 298 and Note 1) that 



I = Cvx. (6) 



* Substitute -^^ — v in (5), therefore 



l^ - F xH 2P i^. 



c-X' 2 p Vx p 



2 -n F xH 2Px'- .a\ 



(J- Z p L p 



Now I has a maximum or minimum when -j- = 0. DifFeren- 



dx 



tiating (8), 



21 dl TT i^/o 2 7 ■,dl\ 4Pa; 

 C- t/a; 2 pC V dx/ p 



Ihereiore when -^ = 0, - .— ^,* oL ■=■ — . 



dx 2 pC px 



I 8P 



C 'SttFx 



Substitute this value in (7), therefore I has a maximum or 

 minimum when 



/ 8P Y 1 4P_ 2P 



* I have to thank Mr. G. I. Taylor, F.R.S., who has very kindly read 

 the first proof-sheets of this paper, for giving me this simple demonstra- 

 tion of (9), from (5) and (6), to replace my own veiy clumsy differentia- 

 tion.-June 8, 1923. 



