RARITY OF GREAT DISCOVERIES. 195 



facts, forces, conditions, or principles, must in every science 

 be much less numerous than those of their quantitative 

 variations. The more complex the nature of a science, 

 also, the greater must be the number of truths of which it 

 is composed and of discoveries effected in finding them. 

 It is clear, then, that great discoveries are far more rare 

 and unlikely to be made than small ones. 



CHAPTER XXI. 



ON UNEXPLAINED PHENOMENA. 



4 IT is well known to chemists that of late years new 

 elementary bodies, new interesting compounds have often 

 been discovered in residual products, in slags, flue-dusts, 

 and waste of various kinds. In like manner, if we care- 

 fully scrutinise the processes either of the laboratory or of 

 nature, we may occasionally detect some slight anomaly, 

 some unanticipated phenomenon which we cannot account 

 for, and which, were received theories correct and suffi- 

 cient, ought not to occur. Such residual phenomena 

 are hints which may lead the man of disciplined mind and 

 of finished manipulative skill to the discovery of new 

 elements, of new laws, possibly even of new forces ; upon 

 undrilled men these possibilities are simply thrown away. 

 The untrained physicist or chemist fails to catch the 

 suggestive glimpses. If they appear under his hands, he 

 ignores them as the miners of old did the ores, cobalt and 

 nickel. . . . This great lesson the importance of residual 

 phenomenefe must be pronounced of the highest moment 

 to the student, and interesting, surely, even to the multi- 

 tude.' 1 



1 Crookes, ' Another Lesson from the Radiometer,' Nineteenth Cen- 

 tivry, July 1877, p. 887. 



o 2 



