540 Scientific Proceedings, Royal Dublin Society. 



fragment of the messages in tlieir 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 he 

 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 he 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. 



1. Determinations such as those dealt with in this Paper have 

 a bearing upon almost every study that is occupied either in th& 

 interpretation of material nature, or in 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. One 

 example of this influence upon other studies is the general limita- 

 tion which molecular determinations impose upon the methods 

 employed in dynamical inquiries, as pointed out in a Paper by the 

 present author on "Texture in Media." [These Scientific Pro- 

 ceedings, vol. vi., p. 392 ; Phil. Mag. for June, 1890, p. 467.] 



2. The direct bearing of the inquiry upon chemistry is obvious. 

 It is briefly referred to in the Scientific Transactions of this 

 Society, vol. iv., p. 608, In fact the record of the chemist 

 is not unlike what one often sees upon a tombstone — " Born in 

 such a year ; Died in such another " ; — while the intervening life 

 is passed over in silence. So the chemist submits two or more 

 substances to their mutual influence, and finds that such and such 



