THE METHOD OF SCIENTIFIC 

 INVESTIGATION 



THE method of scientific investigation is nothing 

 but the expression of the necessary mode of working 

 of the human mind. It is simply the mode at which all 

 phenomena are reasoned about, rendered precise and 

 exact. There is no more difference, but there is just the 

 same kind of difference, between the mental opera- 

 tions of a man of science and those of an ordinary per- 

 son, as there is between the operations and methods of 

 a baker or of a butcher weighing out his goods in com- 

 mon scales, and the operations of a chemist in perform- 

 ing a difficult and complex analysis by means of his 

 balance and finely graduated weights. It is not that 

 the action of the scales in the one case, and the balance 

 in the other, differ in the principles of their construction 

 or manner of working ; but the beam of one is set on an 

 infinitely finer axis* than the other, and of course turns 

 by the addition of a much smaller weight. 



You will understand this better, perhaps, if I give 

 you some familiar example. You have all heard it re- 

 peated, I dare say, that men of science work by means 

 of induction and deduction, and that by the help of 

 these operations, they, in a sort of sense, wring from 

 Nature certain other things, which are called natural 

 laws, and causes, and that out of these, by some cunning 

 skill of their own, they build up hypotheses and theories. 

 And it is imagined by many, that the operations of the 

 common mind can be by no means compared with 

 these processes, and ihat they have to be acquired by a 



