EXAMPLES OF THE FOUR METHODS. 501 



to a superficial view. It is unnecessary to subjoin 

 Sir John Herschel's summary of the result, as it does 

 not contain all the proofs which I have given, and 

 our more detailed analysis of each step of the process 

 renders such a recapitulation unnecessary. 



5. This admirable example will have conveyed 

 to any one by whom it has been duly followed, so 

 clear a conception of the use and practical manage- 

 ment of three of the four methods of experimental 

 inquiry, as to supersede the necessity of any further 

 exemplification of them. The remaining method, 

 that of Residues, not having found any place either 

 in this or in the two preceding investigations, I shall 

 extract from Sir John Herschel some examples of 

 that method, with the remarks by which they are 

 introduced. 



" It is by this process, in fact, that science, in its 

 present advanced state, is chiefly promoted. Most of 

 the phenomena which Nature presents are very com- 

 plicated; and when the effects of all known causes 

 are estimated with exactness, and subducted, the 

 residual facts are constantly appearing in the form of 

 phenomena altogether new, and leading to the most 

 important conclusions. 



" For example : the return of the comet predicted 

 by Professor Encke, a great many times in succession, 

 and the general good agreement of its calculated with 

 its observed place during any one of its periods of 

 visibility, would lead us to say that its gravitation 

 towards the sun and planets is the sole and sufficient 

 cause of all the phenomena of its orbitual motion : 

 but when the effect of this cause is strictly calculated 

 and subducted from the observed motion, there is 



