412 Leigh Page, 



unit force on a like mass at unit distance. The dimensions of m 

 are evidently those of length, and a simple calculation gives the 

 value of this constant for the sun as 1.47 kilometers. 



Integrating (65), it is found that Einstein's theory gives in 

 place of Kepler's law of constant areas the relation 



•6 = cj^(^i-4j), (67: 



where p is the constant of integration. 



To find the equation of a planetary orbit, write {66) in the 

 form 



Substituting the values of 6 from {6y) and writing u for the 

 reciprocal of r, 



= —A/r^ 2Bu-C (68) 



where 



P 



Put 



Then 



2tn / m\ 



B ^ B^- AC 





which gives, on integration 



I _ B^ VB''- AC cos (4/^^ + 8) 

 r~ A 



Substituting for A, B and C their values. 



r_'+V'-^iM{--'>+'\ 



r 



(69) 



