138 ANNUAL OF SCIENTIFIC DISCOVERY. 



eral animals, &c. I concluded from my experiments that, as I was 

 informed there were only a certain number of bodies apt to determine 

 the oscillations of the pendulum, it might be that, in interposing other 

 bodies between the former and the pendulum, the oscillations would 

 cease. 



" Notwithstanding my presumption, my astonishment was great when , 

 after having taken with my left hand a plate of glass or a cake of res- 

 in, &c., and having placed these bodies between the mercury and the 

 pendulum which oscillated over it, I saw the oscillations diminish in 

 length and then wholly cease. They recommenced when the inter- 

 mediate body was taken away, and again ceased upon its re-interpo- 

 sition. This succession of phenomena was repeated a great many 

 times, with a really remarkable constancy, whether the intermediate 

 body was held by me or by any other person. 



" The more extraordinary these effects seemed to me, the more 

 necessary I felt the importance of verifying that they were foreign to all 

 muscular motion of the arm, as I had been informed they were, in the 

 most positive manner. This induced me to lean my right arm, which 

 held the pendulum, upon a wooden support, which at intervals I grad- 

 ually advanced from my shoulder to my hand, and brought back from 

 my hand to my shoulder. I soon noticed that in the first circumstance 

 the motion of the pendulum decreased in proportion as the support 

 was placed near the hand, and that it ceased when the fingers which 

 held the thread were themselves supported, whereas in the second 

 case the contrary effect took place. 



" This induced me to think that it was very probable that a muscu- 

 lar motion which took place unknown to me determined the phenom- 

 ena ; and I was the more inclined to take this opinion into considera- 

 tion as I had a souvenir, vague in truth, of having been in a certain 

 state when my eyes followed the oscillations described by the pendu- 

 lum which I held in my hand. 



" I made the experiments spoken of above over again, my arm be- 

 ing entirely free, and I convinced myself that the souvenir just spoken 

 of was not an illusion of my mind, for I felt very distinctly that, 

 while my eyes followed the oscillations of the pendulum, there was in 

 me a disposition or tendency to tlie motion, which, involuntary as it 

 seemed to be, was the better satisfied as the pendulum described larg- 

 er arcs ; consequently, I thought that if I had repeated the experi- 

 ments, first taking care to blindfold my eyes, the results would be 

 very different from those observed. It happened so exactly. While 

 the pendulum oscillated above the mercury, a blindfold was placed 

 over my eyes ; the motion soon diminished ; but, although the oscilla- 

 tions were feeble, they were not sensibly diminished by the interpo- 

 sition of the bodies, which seemed to have arrested them in my first 

 experiments. 



" Lastly, from the moment the pendulum was at repose, I still held 

 it for a quarter of an hour over the mercury without its moving. Dur- 

 ing this interval, and totally unknown to me, the plate of glass and 

 cake of resin had been interposed and withdrawn several times by per- 

 sons in the room. 



