84 THE ANATOMY OF SCIENCE 



equation for the shortening of moving objects. 

 Another of the most important and certainly 

 the most startling consequences of the principle 

 of relativity will be mentioned in the fifth chap- 

 ter. 



All of the illustrations that I have chosen 

 are such as can be represented in plane dia- 

 grams, but a full appreciation of the wonder- 

 ful parallelism between the new kinematics and 

 the new geometry can only be obtained after 

 examining the complete four-dimensional mani- 

 fold of space and time. There it is possible to 

 build up a body of geometrical propositions 

 which prove to be identical in every detail with 

 the complex theorems of the science of electric- 

 ity and magnetism. 



I am afraid that I have made but a dull busi- 

 ness of this explanation. The principle of rela- 

 tivity is now an old story? but I wish that I 

 could have imparted to you a little of that thrill 

 of excitement which came to us when we first 

 heard the strange but alluring doctrine. I re- 

 member one long summer night through which 

 Richard Tolman and I raised one objection 

 after another, but always in vain, until we were 

 convinced of the truth of relativity, and when 

 with this conviction I, a young chemist, had the 



