APPLICABLE TO MATHEMATICS, &C. 361 



+ Pj m'j = '^ — '^ — ? the effective attracting or 



repelling force according as m P is greater or less 

 than m^ P3 . Hence, if the attractive force is 

 greater than the repelling force at any one point 

 it will always remain greater. Therefore, this 

 supposition of force will not account for the ex- 

 tension of material bodies. 



If we suppose m f(^) = P + P, ^ and ni^ <^{cc) 



= P2 + P3 00 without the conditional equations, 

 then we shall have 



m f(.r) « m' <D(a;) P , Pi / Pj , P3 



^+^^ (28) 



The effective attractive or repulsive force of 



P P 



A on B according as -^ + -^ is greater or less 



than ^ + ^ 



X^ X 



These forces are equal when 



4 + 4- = -5- + 4 • Multiply by cv and 

 we have P + P.x = P^ + V^x 

 3 a 



