was computed on this supposition. The results agreed with the actual 

 masses as experimentally determined. That the mass of a small body 

 electrically charged greatly increases as its velocity approaches that 

 of light is an experimental fact. As matter is made up of such small, 

 rapidly moving, charged, corpuscles, part at least of its mass must 

 be electrical in origin. But the scientist infers that its mass is entirely 

 electrical in origin; for if it were entirely electrical in nature, its mass 

 would be just what its mass in fact is. In other words, the scientist 

 takes mass to be the distinguishing characteristic of matter; he then 

 finds that an electrical charge has exactly this same characteristic. It 

 may be that matter is not electrical in nature and that this correspon- 

 dence is accidental. Yet the theory that matter is electrical has 

 strength; for in our experience such an accidental correspondence 

 would be an anomaly. Here again the scientist has made an as- 

 sumption which so strikingly fits a place in an evidential chain, that 

 its validity seems a credible inference. 



Thus far, we have attempted to state the theories which we wish 

 to study ; to reveal the important steps in the procedure by which each 

 was derived ; and to note the dominant characteristics of the resulting 

 theories. In the succeeding chapter we shall compare and classify the 

 theories in question. 



[12] 



