830 Dynamic Theory. 



affected by the same illusion. If these lines of force could be reflected 

 from a mirror it would seem possible they could be seen by a second 

 person. I have not, however, met with any report of such a case. The 

 scarcity of this sort of illusions with the necessary accompaniments*of 

 mirror, second party on hand in the proper position, &c. , may account 

 for this. 



It would further seem possible to get a photograph from these lines of 

 force. Twenty years ago there was a great interest excited by what 

 was called spirit photography. Very much of it was palpably fraudu- 

 lent. If any were genuine, the phenomena would be accounted for un- 

 der this hypothesis : that the objects photographed were cerebral ideas 

 whose organs projected their agitations into the environment, develop- 

 ing lines of force similar to those which would have been reflected from 

 a solid body. For we are to remember that it is the ra}^s of force that 

 do the business in photography, regardless of their origin, and if we 

 can prove the development of such rays by the action of the brain, the 

 possibility of their decomposing the film on the plate, and making a 

 picture of something, can be conceded without difficulty. 



But if the agitations of internal sight organs are ( under some condi- 

 tions ) competent to set up action in the environing ether, why not those 

 also of other organs ? From what was said in chapter 36 it would ap- 

 pear that wherever there is either polar tension or polar motion, there is 

 a field of force extending in all directions, across which, or in which, 

 the influence of induction is communicated. That the organs of the 

 brain are polar bodies, and the nerve currents, polar currents, hardly ad- 

 mits of doubt. It follows that they may be surrounded by fields of 

 force, across which they may send their inductive influence. ( See figs. 

 143, 144.) There are many facts going to show that this is the case. 

 The different sensations set up in us by the action of different brain or- 

 gans, may be supposed to indicate differences in pitch in the movements 

 peculiar to the organs. When these influences, projected into the envi- 

 ronment of the brain, come into contact with the brain of another per- 

 son which may be within the same field, the corresponding* organs of 

 the latter brain are affected so as to take up a motion like that of the 

 first, so that a sensation is aroused in the second brain similar to that in 

 the first. As it is stated rather inaccurately in common language, there 

 has been a transference of thought. (See chapter 79.) 



That illusions are due to a$i unequal stimulation of organs, is shown 

 where spectral illusions arise from the fatigue of overstimulation of a 

 part of the organs concerned. Darwin performed this experiment. Upon 

 a yellow paper, four inches square, he wrote in blue capitals the word 

 BANKS. Then, with his back to the sun, he gazed a minute exactly 

 on the middle letter. Then closing his e}-es, he could see the word in 



