NATURALISTS CABINET. 



Rheaumur's exposition. 



feels nothing: if he touch it with a stick, he 

 feels a faint effect: if he touch it through the. 

 interposition of any pretty thin body, the numb- 

 ness is felt very considerably ; if the hand be 

 pressed very strong against it, the numbness is 

 the less, but still strong enough to oblige a man , 

 speedily to let go. 



Rheaumur accounts for this phenomenon in 

 the following manner : the torpedo, like other 

 flat-fish, is not absolutely flat; but its back, or 

 rather all the upper parts of its body, a little con- 

 vex : when it did not, or would not produce any 

 numbness in such as touched it, its back he 

 found, always preserved its natural convexity ; 

 but whenever it would dispose itself to resent a 

 touchj or thrust, it gradually diminished the con- 

 vexity of the back parts of the body, sometimes 

 only rendering them flat, and sometimes con- 

 cave. The next moment the numbness always 

 begins to seize the arm ; the fingers that touched 

 were obliged to give back, and the flat and con- 

 cave part of the body was seen again convex, and 

 where as it only became flat insensibly, it returned 

 to its convexity so swiftly that one could not per- 

 ceive any passage from the one to the other state. 



The motion of a ball out of a musket is not 

 perhaps much quicker than that of the fish re- 

 assuming its situation ; at least the one is not 

 more perceivable than the other. It is from this 

 sudden stroke that the numbness of the arm 

 arises; and accordingly the person, when he be- 



