424 Dr. G. J. Stoney on the 



to them, comparable with some such period as twenty or 

 thirty thousand years in its relation to man's slow thoughts, 

 or the driftings about of those accumulations of molecules 

 which are the only kind of objects he can perceive even 

 with the highest powers of his microscope. These visible 

 objects, these armies of molecules massed together, seem to 

 him sometimes at rest and sometimes in motion ; but in 

 either case strenuous activity within and between the mole- 

 cules themselves never ceases, nor the perpetual response 

 between them and the aether through which they keep up a 

 communication with one another at a distance. The magni- 

 tude of the consequences throughout all Nature of this 

 unflagging intercourse between molecules cannot be ap- 

 proached by the utmost thought we can give to it. It is 

 quite impossible for us to appreciate it adequately. The 

 human eye placed anywhere intercepts a small fragment of 

 the messages in their transit, and is thus a detector of their 

 presence. But it does so roughly. It jumbles up the 

 immense detail which even our spectroscopes can show to be 

 included within this fragment. Yet even so, how much our 

 eyes show us wherever we turn them, and with what seems 

 to us such marvellous promptness ! The spectroscope in 

 some respects penetrates farther as a detector. Even it, 

 however, fails to reach much detail that we know to be 

 present, e. g, it cannot tell us the innumerable interruptions 

 or the various orientations or the phases of the actual motions. 

 And, at the best, both these detectors together can give us 

 but a very slender notion of the real activity that is going on, 

 and of the precision and fulness with which the molecules 

 everywhere about us are energetically exchanging many 

 millions of different messages with one another every second. 

 Such is Nature as it really is. 



XI. On the Bearing of these Determinations on other 

 Branches of Study. 



Determinations such as those dealt with in this paper have 

 a bearing upon almost every study that is occupied either in 

 the interpretation of material Nature, or investigating the 

 relation between the thoughts of animals and the operations 

 that go on in their brains ; inasmuch as the whole of material 

 Nature is found, on careful analysis, to rest on molecules — 

 on their mutual relations and motions, on the events going on 

 within the molecules, and on those which they excite in the 

 medium in which they move. 



1. One example of this influence upon other studies is the 

 general limitation which molecular determinations impose 



