288 



a) A // > O 



A F^O 



L H'yO 



A r' > 



aLH' - (1 + 6) A //>0 



6) LHya AF^O 



a A //•' — (! -\-b) LIK^O 



c) Ai/>0 AF^O 



a A /i' - (I + /.) A /^<0 



(24) 



(25) 



a A F' - (1 + 6) A F>0 



L/i'yo A F' > 



a A F' — (1 -f 6) A F > 



A//'<0 AF'>0 j (26) 



a A F' — (1 + 6) A F>0 



111 eacli of tlie three cases, mentioned ahove, is in (21) the coef- 

 ficient of ./', negative and of c, positive; conseqnentiy we liave: 



(1 + a) A V' 



{dl\ > when ~ ^ 



(27) 



x^<~aL F' — (1 + ft) A F 



As A V' is very large with respect to A V it follows from this 

 approximately with tiie aid of (23): 



(dT)^>Q when ^>?— ^ 



(28) 



In the case, mentioned snb h in (22) tiie ooefficieiils of .c, and ,r, 

 are negative, so that {dP)x is also negative ; conseqiientij the pressnre 

 is lowered. 



In order to examine more in detail the sign of [dP)x we write 

 for (22) 



LH' 1+a 



M{dP)x = 



1+6 a 



LH' — Afi 



^ . 



(29) 



wherein : 



Nizza A ƒƒ'- (1 + 6) A// 



When we put herein the value of a from (23) then we may write 

 for (29): 



M.(dP)x 



LH' 



y—;u 



lh'-^-^lh"^ 



Nx, 



(30) 



When we consider the three cases a, b and c mentioned above, 

 then we may write for (30) : 



a) 



(dP), = 

 (,/P), = _ 



{dP).,- 





X, 



+ K 



y—Vi- 

 ,y—y^ 





• (31) 

 . (32) 



• (33) 



