52 feature's /HMracleS. 



tablished in the circuit, similar to the closed 

 circuit of magnetic lines of force, only the 

 latter is static, while the former is dynamic. 



You ask what is the difference? Well, it is 

 much easier to ask a question than it is to 

 answer it. You will remember that in the 

 chapter on magnetism it was stated that the 

 molecules of a magnet were little natural mag- 

 nets, and that their attractions were satisfied 

 within themselves; that when their local at- 

 tachments were broken up and all their like 

 poles turned in one direction they could act 

 upon other pieces of iron outside of the mag- 

 net. Outside and between the poles there are 

 magnetic lines of force reaching out from one 

 pole to the other. If we put a piece of iron 

 across the poles these lines of force are 

 gathered up and pass through the iron. This 

 is purely a static condition. Let us go back to 

 the cell of battery. When the elements are in 

 position (the copper, the acidulated water and 

 the zinc), and the two wires attached to the 

 two metals which are the two poles of the bat- 

 tery not yet connected, there is a condition in- 

 duced in these two wires that did not exist be- 

 fore the acidulated water was poured in, al- 

 though the circuit is not yet established. If 

 we test the two wires we find a difference of po- 

 tential a state of strain, so to speak that did 

 not exist before the acid acted on the zinc and 

 liberated what was stored energy. It is in a 



