THE CORRELATION OF THE PHYSICAL FORCES 81 



battery, and bring the points in contact. See what an 

 exhibition of force we have! We have exhausted the air 

 so that the charcoal can not burn, and therefore the light 

 you see is really the burning of the zinc in the cells behind 

 me; there is no disappearance of the 

 carbon, although we have that glori- 

 ous electric light; and the moment 

 I cut off the connection it stops. 

 Here is a better instance to enable 

 some of you to see the certainty 

 with which we can convey this 

 force, where under ordinary circum- 

 stances, chemical affinity would not 

 act. We may absolutely take these 

 two charcoal poles down under 

 water, and get our electric light 

 there. There they are in the wa- 

 ter, and you observe, when I bring 

 them into connection, we have the 

 same light as we had in that glass 

 vessel. 



Now besides this production of 



light, we have all the other effects and powers of burning zinc. 

 I have a few wires here which are not combustible, and I am 

 going to take one of them, a small platinum wire, and suspend 

 it between these two rods which are connected with the 



FIG. 48 



battery, and when contact is made at the battery see what 

 heat we get (FiG. 48). Is not that beautiful? It is a 

 complete bridge of power. There is metallic connection 



