PBEFACE. 



THE OBJECT of the following treatise is to describe the 

 nature of original Scientific Kesearch, the chief personal 

 conditions of success in its pursuit, the general methods 

 by which discoveries are made in Physics and Che- 

 mistry, and the causes of failure ; and thus to elucidate, 

 so far as possible, the special mental conditions and 

 processes by means of which the mind of man ascends 

 from the known to the unknown in matters of science. 

 Some of the conditions described are such as I have in 

 my own experience found to be necessary, and some of the 

 methods are those I have frequently employed in my own 

 researches. 



Many young scientific men hesitate to undertake ori- 

 ginal research from a fear of the great difficulty of the 

 task, and of repeating experiments which others have 

 already made, and also because they do not know how to 

 select suitable subjects ; and, as one of the most effectual 

 preliminary conditions of ensuring success in research is a 

 thorough study of the general and special methods and 

 conditions of discovery, it is hoped that such persons will 



