FALLACIES OF TESTIMONY. 251 



"man of thorough integrity, has for many years enjoyed the 

 " reputation of being specially skilled in the finding of places to 

 " dig wells by means of the * divining rod.' His fame has spread 

 *' far ; and the accounts that are given by him, and of him, must 

 " be to those who place an implicit reliance on human testimony 

 "overwhelmingly convincing. He consented to allow me to 

 " experiment with him, and I found that only a few moments 

 "were required to prove that his fancied gift was a delusion. In 

 " his own yard there was known to be a stream of water running 

 "a few feet below the surface, through a small pipe. As he 

 " marched over and near this, the rod continually pointed 

 " strongly downwards, and several times turned clear over. 

 "These places I marked, and then blindfolded him, and 

 "marched him about until he knew not where he was, taking 

 "him over the same ground over and over again ; and although 

 " the rod went down a number of times, // did not once point to 

 " or near the places indicated." 



3. About twenty-five years ago, when the old phenomena of 

 the oscillations of suspended buttons, developed by Dr. H. Mayo 

 into a pseudo-scientific theory of od-force, were strongly exciting 

 public attention, a medical friend of great intelligence, then 

 residing in the south of France, wrote me long letters giving the 

 results of his surprising experiences, and asking what I regarded 

 as their rationale. My reply was simply, — " Shut your eyes, and 

 let some one else observe the oscillations." In a short time I 

 heard from him again, to the effect that his re-investigation of 

 the matter under this condition had satisfied him that there was 

 no other agency concerned than his own involuntary muscular 

 movement, directed by his mental expectancy of the results which 

 would ensue. 



In the foregoing cases, the honest beliefs of the agents them- 

 selves brought about the results ; in the following, these beliefs 

 were taken up by the witnesses to the performances of others, in 

 spite of all common-sense probability to the contrary, under the 

 influence of their own strong "prepossessions." 



4. At a spiritualistic seance at which I was present, at an early 

 stage of the present epidemic, the " medium " pressed down one 



