Continuity 1 1 



everywhere and always, or whether the 

 Newtonian scheme must be replaced by 

 something more modern, something to 

 which Newton's laws of motion are but 

 an approximation. 



Indeed a whole system of non-New- 

 tonian Mechanics has been devised, 

 having as its foundation the recently 

 discovered changes which must occur in 

 bodies moving at speeds nearly com- 

 parable with that of light. It turns out 

 in fact that both Shape and Mass are 

 functions of Velocity. As the speed 

 increases the mass increases and the shape 

 is distorted, though under ordinary con- 

 ditions only to an infinitesimal extent. 



So far I agree; I agree with the state- 

 ment of fact; but I do not consider it so 

 revolutionary as to overturn Newtonian 

 Mechanics. After all, a variation of Mass 

 is familiar enough, and it would be a 

 great mistake to say that Newton's 

 second law breaks down merely because 

 Mass is not constant. A raindrop is an 

 example of variable mass; or the earth 

 may be, by reason of meteoric dust; or 



