72 



= ....-.... (15) 

 a 



R 

 For w we have at our surface: 



a c 

 1-7. = - (16) 



This may be proved e.g. by putling e =z in formula (12) II 

 which holds outside our surface. Also b}' putting r=R we obtain 

 the value (16) at the surface, and formula (9j shows afterwards (as 

 within the surface n = 1 and T/ = 0), that this constant value of 

 IÜ holds also every whei-e inside the material surface. 



Introducing the expressions u^, Uj, and w, we find for the surface 

 tension P 



This formula expresses the relation between the surface-tension, 

 the mass and the radius. Expressed in the usual units, the surface- 

 tension is cP (comp. I p. 1079). The constant of mass « is also con- 

 Jiected with the right-hand side of equation (8). After inti-oduction 

 of the values of u^ and w, this equation gives 



'2 

 a ^ a R^ Urn I 7'. 



dr. ...... (18) 



In the euclidic space inside the material surface we have not the 

 same velocity of light as at an infinite distance from our system, 

 but a smaller velocity 



« 



1 . 



R 



We thus have a representation of Einstein's idea on the influence 



of distant masses on the velocity of light in our part of the world. 



Expanding the expression (17) for P in powers of ajR we obtain : 



P= T hi h-.- .... (17a) 



2yiRy R' ^ R'^ J ^ ^ 



Newton's theory gives for cP: 



where k is the Newtonian gravitation constant: 



8jr 



