EVOLUTION AND MUTABILITY OF 'MATTER; 269 



movement far away from cities, where the mercurial 

 mirror of a seismoscope showed no subterranean 

 vibration. It does not increase when the vibrations 

 occur and become quite appreciable. Neither is it 

 changed by variation in light, magnetism, or electric 

 influences ; in a word, by any external occurrences. 

 The result of observation is to place before us the 

 paradox of a phenomenon which is kept up and 

 indefinitely perpetuated in the interior of a body 

 without known external cause. 



The Broivnian Movement must be tJie First Stage of 

 Molecular Motion. — When we take in our hands a 

 sheet of quartz containing a gaseous inclusion, we 

 seem to be holding a perfectly inert object. When 

 we have placed it upon the stage of the microscope, 

 and have seen the agitation of the bubble, we are 

 convinced that this seeming inertia is merely an 

 illusion. 



Repose exists only because of our limited vision. 

 We see the objects as we see from afar a crowd of 

 people. We perceive them only as a whole, without 

 being able to discern the individuals or their move- 

 ments. A visible object is, in the same way, a mass 

 of particles. It is a molecular crowd. It gives us 

 the impression of aji indivisible mass, of a block in 

 repose. 



But as soon as the lens brings us near to this 

 crowd, as soon as the microscope enlarges for us the 

 minute elements of the brute body, then they appear 

 to us, and we perceive the continual agitation of those 

 elements which are less than four thousandths of a 

 millimetre in diameter. The smaller the particles 

 under consideration, the more lively are their move- 

 ments. From this we infer that if we could perceive 



