CONDUCTION OF ELECTRICITY AND HEAT. 123 



electricity is gone at once dispersed on the 

 instant, in a manner wonderful to think of. 



I must now take up a little of your time in 

 showing you the manner in which these powers 

 are transferred from one thing to another ; for 

 the manner in which force may be conducted 

 or transmitted is extraordinary, and most es- 

 sential for us to understand. Let us see in what 

 manner these powers travel from place to place. 

 Both heat and electricity can be conducted ; and 

 here is an arrangement I have made to show 

 how the former can travel. It consists of a bar 

 of copper (fig. 42), and if I take a spirit-lamp 



Fig. 42. 



(this is one way of obtaining the power of heat) 

 and place it under that little chimney, the flame 

 will strike against the bar of copper and keep it 



