THE DIVINING-ROD 395 



elusions. You must find out the details of the nature 

 of A and also of B, and if possible how the one is 

 connected with the other. And if you cannot do that 

 you can still establish your conclusion and confirm your 

 guess by showing that B invariably follows upon A, or 

 that (in a long experience) only when A has been 

 present, and never when A has not been present, has 

 B occurred. If you cannot prove the truth of your 

 guess by this experimental demonstration of the ex- 

 clusion of other causes than A or by the experimental 

 demonstration of the invariable occurrence of B after A 

 has occurred, then you have to seek for evidence of a 

 real connexion between A and B, though not an in- 

 variable one, by collecting a vast number of instances of 

 the occurrence of B and finding out whether A has 

 preceded it in such a large proportion of cases (as 

 compared with those in which B has occurred without 

 the previous occurrence of A) that the cases in which B 

 follows A cannot be considered as accidental, but in- 

 dicate a real causal relation of A to B. 



This is always a difficult undertaking, whether we 

 start with the guess that B is caused by A or that it is 

 not caused by A. In the case of water-finding, water is 

 found at depths of 30 feet to 100 feet and more below 

 the surface by engineers without the aid of " dousers " 

 every day, and this is so frequent and regular a proceed- 

 ing that the percentage of cases in which dousers find 

 water, that is to say in which B — the discovery of water 

 — follows A (A being the employment of a supposed 

 sensitive douser with or without his twig) does not — so 

 far as I am able to judge without strict statistical" 

 evidence — exceed the percentage of successes in search- 

 ing and digging for water by ordinary intelligent men 

 without the introduction of A. 



