54 nature's 



only energy. We do not mean to say that the 

 row of bricks illustrates the exact mode of 

 molecular or atomic motion that takes place in 

 a conductor. What we mean is, that in some 

 way motion is passed along from atom to atom. 

 To give you a better conception of an elec- 

 tric current, let us go back of the galvanic cell 

 to the electric machine. If both poles of the 

 machine are attached to rods terminating in 

 round knobs we can set the machine in action 

 and keep up a steady stream of disruptive dis- 

 charges that will, if their frequency is great 

 enough, perform the function of a current, and 

 we have dynamic electricity from a statical 

 machine; when the acid of the galvanic bat u-ry 

 breaks down a molecule of zinc, energy is set 

 free, and in the battery we have what corre- 

 sponds to a disruptive discharge of infinites- 

 imal proportions. This discharge would have 

 been immediately converted into heat energy 

 if the copper element had been left out of the 

 battery, but as it is, it impresses itself on the 

 atomic "brick" next to it, which establishes 

 a chain of atomic movement throughout the 

 circuit. This may constitute, if you please, a 

 line of electrical force. But as thousands of 

 these disruptive discharges are taking place 

 simultaneously as many different lines of 

 force are established. You must not conceive 

 of these chains of atoms as simply thrown 

 down like the bricks and left lying there, but 



