260 POPULAR LECTURES AND ADDRESSES. 



possess, in anything like the same degree as copper 

 and silver, the quality I am now going to call 

 attention to. 



The quality I refer to is " electric conductivity," 

 and the result of that quality, in the experiment I 

 am now going to describe, is that a piece of 

 copper or a piece of silver, let fall between the 

 poles of a magnet, will fall down slowly as if it 

 were falling through mud. I take this body and 

 let it fall. Many of you here will be able to 

 calculate what fraction of a second it takes to fall 

 one foot. If I took this piece of copper, placed it 

 just above the space between the poles of a power- 

 ful electro-magnet and let it go, you would see 

 it fall slowly down before you ; it would perhaps 

 take a quarter of a minute, to fall a few inches. 



This experiment was carried out in a most 

 powerful manner, by Lord Lindsay (now Lord 

 Crawford), assisted by Mr. Cromwell F. Varley. 

 Both of these eminent men desired to investigate 

 the phenomena of mesmerism, which had been 

 called animal magnetism ; and they very earnestly 

 set to work, to make a real physical experiment. 





