A MODEL OF NATURE. 175 



SUCCESSIVE STEPS IN THE ANALYSIS <)V MATTER. 



In dealing, then, with the question of the constitution of matter and 

 the possibility of representing it accurately, we may grant at once 

 that the ultimate nature of things is. and must remain, unknown; hut 

 it does not follow that immediately below the complexities of the 

 superficial phenomena which affect our senses there may not he a 

 simpler machinery of the existence of which we can obtain evidence, 

 indirect, indeed, but conclusive. 



The fact that the apparent unity which we call the atmosphere can 

 be resolved into a number of different gases is admitted; though the 

 ultimate nature of oxygen, nitrogen, argon, carbonic acid, and water 

 vapor is as unintelligible as that of air as a whole, so that the analysis 

 of air may be said to have substituted many incomprehensibles for one. 



Nobody, however, looks at the question from this point of view. 

 It is recognized that an investigation into the proximate constitution 

 of things may be useful and successful, even if their ultimate nature 

 is beyond our ken. 



Nor need the analysis stop at the first step. Water vapor and car- 

 bonic acid, themselves constituents of the atmosphere, are in turn 

 resolved into their elements, hydrogen, oxygen, and carbon, which, 

 without a formal discussion of the criteria of reality, we may safely 

 say are as real as air itself. 



Now, at what point must this analysis stop if we are to avoid cross- 

 ing the boundary between fact and fiction? Is there any fundamental 

 difference between resolving air into a mixture of gases and resolving 

 an elementary gas into a mixture of atoms and ether? 



There are those who cry halt at the point at which we divide a gas 

 into molecules, and their first objection seems to be that molecules and 

 atoms can not be directly perceived, can not be seen or handled, and 

 are mere conceptions, which have their uses, but can not be regarded 

 as realities. 



It is easiest to reply to this objection by an illustration. 



The rings of Saturn appear to be continuous masses separated by 

 circular rifts. This is the phenomenon which is observed through a 

 telescope. By no known means can we ever approach or handle the 

 rings; yet everybody who understands the evidence now believes that 

 they are not what they appear to be, but consist of minute moonlets, 

 closely packed, indeed, but separate the one from the other. 



In the first place, Maxwell proved mathematically that if a Saturn - 

 ian ring were a continuous solid or fluid mass it would be unstable 

 and would necessarily break into fragments. h\ the next place, if it 

 were possible for the ring to revolve like a solid body, the inmost 

 parts would move slowest, while a satellite moves faster the nearer it 

 is to a planet. Now, spectroscopic observation, based on the beautiful 



