THE CORRELATION OP THE PHYSICAL FORCES 8> 



they fall. What can show you better than such an ex- 

 periment as this the magnetic attraction with which we have 

 endowed these portions of iron? Here, again, is a fine 

 illustration of this strong power of magnetism. It is a mag- 

 net of the same sort as the one you have just seen. I am 

 about to make the current of electricity pass through the wires 

 which are round this iron for the purpose of showing you 

 what powerful effects we get. Here are the poles of the 

 magnet; and let us place on one of them this long bar 

 of iron. You see, as soon as contact is made, how it rises in 

 position (Fie. 54) ; and if I take such a piece as this cylinder, 



FIG. 54 



and place it on, woe be to me if I get my finger between ; I 

 can roll it over, but if I try to pull it off, I might lift up the 

 whole magnet, out I have no power to overcome the magnetic 

 power which is here evident. I might give you an infinity of 

 illustrations of this high magnetic power. There is that long 

 bar of iron held out, and I have no doubt that if I were to ex- 

 amine the other end I should find that it was a magnet. See 

 what power it must have to support not only these nails, but 

 all those lumps of iron hanging on to the end. What, then, 

 can surpass these evidences of the change of chemical force 

 into electricity, and electricity into magnetism ? I might show 

 you many other experiments whereby I could obtain elec- 

 tricity and chemical action, heat and light from a magnet, but 

 what more need I show you to prove the universal cor- 

 relation of the physical forces of matter, and their mutual 

 conversion one into another i. 



