viii.] Table-Tippers. 121 



no warrant whatever, save in a general a priori hypo- 

 thesis, handed down to us from barbarous times, 

 which has been uniformly discredited wherever there 

 has been an opportunity for testing it. Even to 

 describe such a " force " as " psychic " is to beg the 

 whole question ; for until we have subjected it to a 

 long course of experimentation, like that which has 

 built up our scientific knowledge of heat and light, 

 we can have no means of knowing whether it is 

 " psychic " or not. 



It is, however, very unphilosophical at the outset 

 to appeal to any new or unknown force until we 

 have thoroughly exhausted all means of explanation 

 furnishable by forces that have already been de- 

 fined ; and by the advocates of spiritualism no such 

 preliminary inquiry has ever been made or even 

 attempted. When, therefore, Mr. Crookes finds 

 himself unable to explain the way in which Mr. 

 Home causes the index of a spring-balance to de- 

 scend without exerting any apparent pressure on 

 the lever, it is a very violent stretch of inference to 

 call in an imaginary " psychic force " by way of 

 simplifying the matter. This is appealing from the 

 known to the unknown, and it is in no such way that 

 discoveries are made in those physical sciences which 

 Mr. Crookes has so carefully studied. Dr. Hammond 



