VI PREFACE. 



be induced to attempt original investigation by the aid of 

 the suggestions contained in this book. 



Although men have during all modern time made dis- 

 coveries in Physics and Chemistry, and many eminent 

 investigators have occupied and are still occupying a large 

 portion of their lives in original scientific research, the 

 conditions of success and failure in the pursuit of original 

 scientific inquiry, and the methods employed in making 

 discoveries, remain for the most part unknown to ordinary 

 persons. 



In nearly all cases investigators, from some cause or 

 other, have not troubled themselves to describe the actual 

 circumstances which gave rise to their discoveries, and 

 have thus failed to leave behind them the ladder by which 

 they ascended, and by which others might, to some extent 

 at least, have been assisted in the pursuit of similar ob- 

 jects. Faraday, and particularly Kepler, did, however, 

 leave an account of a few of the failures as well as the 

 successes of their researches. The biographies of such 

 men, and also some other books, such as Thomson's His- 

 tories of Chemistry and of the Royal Society ; Whewell's 

 ' History of the Inductive Sciences,' and his Philosophy of 

 those sciences ; Archbishop Thomson's ' Laws of Thought ;' 

 Sir John Herschel's ' Discourse on Natural Philosophy ; ' 

 Jevons's ' Principles of Science ; ' Buckley's ' Short History 

 of Natural Science,' and a few other books, contain, in 

 fragmentary portions, a large amount of information of 

 great value to an original scientific investigator. The 

 object of the present treatise, however, is different. It is 

 to describe in a concise form the general course of pro- 



