THE SIX G A TEW A YS OF KNOWLEDGE. 263 



that would annul practically the action, due to 

 the electric force, in the interior; and this sur- 

 face action would be a definite sensation which 

 we could distinctly trace to the sense of touch. 

 Any one putting his hand, or his face, or his hair, 

 in the neighbourhood of an electric machine, per- 

 ceives a sensation, and on examining it he finds 

 that there is a current of air blowing and that his 

 hair is attracted ; and if he puts his hand too near, 

 he finds that there are sparks passing between his 

 hand or face, and the machine ; so that before we 

 come to any subtle question of a possible sense of 

 electric force, we have distinct mechanical agencies, 

 which give rise to senses of temperature and force. 

 But that this mysterious wonderful magnetic force, 

 due, as we now know, to rotations of the molecules, 

 could be absolutely without effect without per- 

 ceptible effect on animal economy, seems a very 

 wonderful result, and at all events it is a subject 

 deserving careful investigation. I hope no one 

 will think that I am favouring the superstition of 

 mesmerism in what I have said. 



I intend to explain a little more fully our 



