74 THE ANATOMY OF SCIENCE 



this same constant, 300,000 kilometers per sec- 

 ond, was discovered by Weber in his study of 

 electrical charges and magnets. If we had never 

 known light or any other form of radiant 

 energy this constant would still play an impor- 

 tant part in all of mathematical physics. 



Of course the numerical value of this constant 

 depends upon whether we measure velocity in 

 kilometers per second or miles per minute, and 

 it would be a great simplification of many of 

 our equations of physics if units were so chosen 

 as to make this velocity itself equal to unity. 

 This suggestion has been repeatedly made 

 throughout a half -century,* and will certainly 

 be generally adopted before long. It will sim- 

 plify my task if I adopt it here. Thus if we 

 keep the centimeter as the unit of length, we 

 must choose a very small unit of time, which I 

 have somewhat jocularly called the jiffy, — so 

 that the velocity of light becomes one centimeter 

 per jiffy. 



The repeated appearance of a unique ve- 

 locity in the various branches of physics is in no 

 way suggested by that geometry which we have 

 shoAvn to be a counterpart of the Newtonian 

 kinematics, and therefore at once arouses suspi- 



4 See Sundell, Philosophical Magazine, 1882. 



