14G Prof. A. M e Aulay on Spontaneous Generation 



or restoring the meanings of m, m", and e 



-SV^(S 2 V^ + SVViV 2 Vw 2 -V 2 V^)] I 

 + f(±l-2/>)[SV^(S 2 V^ + 2SW l V 2 V^ 2 [ ' * l } 



-Y>~Vv)-2S(YVv)x(yVy)] J 

 For free aether the strains are small compared with b, and 

 we have 



(free aether) v/A=(2b + ic)$ 2 W-§°V s Vy. . . (50) 



This equation is known to give wave propagation of curl with 

 velocity ^/[(A/ft^] and wave propagation of divergence 

 with velocity N /[(A/n)(46 + -|c)]. The first is necessarily 

 less than the second, and familiar considerations incline us 

 to put it as very much less by supposing, as is necessary for 

 the purpose, that b is very much less than c. We now make 

 this assumption ; partly, of course, because otherwise (49) 

 seems intractable. With c/b thus large there is always the 

 possibility some time of explaining gravitation as due to c. 



The discussion above, by aid of the diagram, shows that 

 in the middle of a web or thread or knot we must suppose 

 south valley conditions to hold. As we pass in space from 

 the middle, the representing point on the diagram passes by 

 some path near the saddle towards the lake bottom, and the 

 mean condition of matter in bulk will be represented by a 

 point probably between the lake bottom and the saddle. 

 Thus in (49) in the neighbourhood of an electron we must 

 suppose Y\jv an d % to be of the order b, while ^>\Jrj is of a 

 neolioibly smaller order such as b 2 /c. Rejecting all but the 

 most important terms thus given we get 



v/A= -#Y 2 V^ + |S(YV77)x(YV^), SV?? = 0. (51) 



The condition $XJr) = must be taken account of by inde- 

 terminate multipliers when applying the principle 8§Idt> 

 It is easy to see that this gives a term — Vi-> in ny, p being 

 a scalar, that is we must include the effect of a hydrostatic 

 pressure in our equation of motion. 



We digress here to comment on the general nature of (51). 

 It was above asserted that the elastic solid theory had not 

 been so much as tried in the light of modern views concerning 

 the aether. (51) has been arrived at in a most inartificial 

 manner. We have simply examined the general nature of 

 the modern views, and have then postulated as simple a con- 

 stitution as can be well thought of for our solid, with no 



