EXAMPLES OP THE FOUR METHODS. 471 



and prolongation of the cadaveric rigidity. This investigation 

 places in a strong light the value and efficacy of the Joint 

 Method. For, as we have already seen, the defect of that 

 Method is, that like the Method of Agreement, of which it is 

 only an improved form, it cannot prove causation. But in the 

 present case (as in one of the steps in the argument which led 

 up to it) causation is already proved ; since there could never 

 be any doubt that the rigidity altogether, and the putrefaction 

 which follows it, are caused by the fact of death : the obser- 

 vations and experiments on which this rests are too familiar to 

 need analysis, and fall under the Method of Difference. It 

 being, therefore, beyond doubt that the aggregate antecedent, 

 the death, is the actual cause of the whole train of con- 

 sequents, whatever of the circumstances attending the death 

 can be shown to be followed in all its variations by variations 

 in the effect under investigation, must be the particular feature 

 of the fact of death on which that effect depends. The degree 

 of muscular irritability at the time of death fulfils this con- 

 dition. The only point that could be brought into question, 

 would be whether the effect depended on the irritability itself, 

 or on something which always accompanied the irritability : 

 and this doubt is set at rest by establishing, as the instances 

 do, that by whatever cause the high or low irritability is pro- 

 duced, the effect equally follows ; and cannot, therefore, depend 

 upon the causes of irritability, nor upon the other effects of 

 those causes, which are as various as the causes themselves ; 

 but upon the irritability, solely. 



5. The last two examples will have conveyed to any 

 one by whom they have been duly followed, so clear a concep- 

 tion of the use and practical management 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 a place in any of the pre- 

 ceding investigations, I shall quote 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 



