378 ACTUAL WORKING IN ORIGINAL RESEARCH. 



which would probably prevent or diminish the expected 

 effect ; and then to arrange the most delicate means of 

 detecting, and, if necessary, also measuring the effect. 



These being provided, a few preliminary experiments 

 may now be made, and as many conclusions drawn from 

 the results of them, and from comparisons of the results 

 with each other, as are proved by the evidence. During 

 these experiments as many hypotheses as possible should 

 be raised by studying the results and conclusions, and 

 notes be kept of all the results, conclusions, remarks, and 

 hypotheses for future reference. 



The sources of error and interference should now be 

 excluded, and the phenomenon be obtained, or the method 

 of working be arrived at, in a pure or perfect state and free 

 from unessential conditions, as soon as possible. This is 

 effected by selecting those hypotheses which bear upon 

 the particular points, and testing them by additional ex- 

 periments and observations, in which each condition is ex- 

 cluded, one only at a time ; and this usually requires very 

 varied experiments and considerable thought and trouble. 



Having at length obtained, by means of these addi- 

 tional experiments, an approximately perfect form of the 

 phenomenon or method of working, the next step is to 

 make a systematic and comparatively exhaustive examina- 

 tion of each condition of the phenomenon or method, and 

 also to make the experiment with, or employ the method 

 upon, every suitable substance. By making the experi- 

 ment with every possible substance, the greatest number 

 of conspicuous and exceptional cases will be included ; 

 exhaustive researches also generally yield the greatest 

 discoveries, because it is the exceptional cases of the ex- 

 ceptional ones which disclose in the greatest degree the 

 most hidden conditions. During this examination every 

 logical conclusion possible should be drawn from the 



