XXX11 PREFACE. 



From the moment that we begin to look earn- 

 estly and conscientiously for the true answers 

 to our questions ; that we take the trouble, 

 by means of weight and measure, to fix our 

 observations, and express them in the form of 

 equations, these answers are obtained without 

 difficulty. 



However numerous our observations may be, 

 yet, if they only bear on one side of a ques- 

 tion, they will never enable us to penetrate the 

 essence of a natural phenomenon in its full 

 significance. If we are to derive any advan- 

 tage from them, they must be directed to a 

 well-defined object ; and there must be an or- 

 ganized connexion between them. 



Mechanical philosophers and chemists justly 

 ascribe to their methods of research the greater 

 part of the success which has attended their 

 labors. The result of every such investigation, 

 if it bear in any degree the stamp of perfec- 

 tion, may always be given in few words ; but 

 these few words are eternal truths, to the dis- 

 covery of which numberless experiments and 

 questions were essential. The researches them- 

 selves, the laborious experiments and compli- 

 cated apparatus, are forgotten as soon as the 

 truth is ascertained. They were the ladders, 

 the shafts, the tools, which were indispensable 

 to enable us to attain to the rich vein of ore ; 



