THE FOUR EXPERIMENTAL METHODS. 479 



laws of the succession of phenomena. Before pro- 

 ceeding to point out certain circumstances, by which 

 the employment of these methods is subjected to an 

 immense increase of complication and of difficulty, it 

 is expedient to illustrate the use of the methods, by 

 suitable examples, drawn from actual physical inves- 

 tigations. These, accordingly, will form the subject 

 of the succeeding chapter. 



