CHAPTER XVI 



TWO BELATED FORCES MAN HAS HARNESSED 

 MAGNETISM AND ELECTRICITY 



Magnetism. So much were some of the ancients im- 

 pressed with the property of loadstones (page 37) for attract- 

 ing iron that one of them suggested building a great arch 

 of this material in a temple so that the iron statue of the 

 goddess would remain suspended in the air without resting 

 upon any support. There is an old legend that the iron 

 coffin of Mahomet rose and remained near the ceiling of the 

 mosque in which it was buried. 



Experiment 147. Touch with each end of a bar magnet small 

 pieces of paper, copper, zinc, iron, sawdust, and any other materials 

 that may be handy. Which substances are attracted by the 



magnet ? Does it make any difference which end is 



used ? Take a knife blade that has no such attrac- 

 tive power and rub it several times along one end 

 of the magnet ; then touch the different substances 

 with it. Has it acquired any new power? 



Experiment 148. Suspend a bar magnet hori- 

 zontally in a sling made from a bent piece of wire 

 (Figure 148). Bring one of the ends of another bar 



magnet toward it. What is the effect ? Reverse the 



, , , . , , . , , FIGURE 148 



ends of the magnet ; is there any change in the posi- 

 tion of the suspended magnet? Bring a large, soft iron nail toward 

 either end of the suspended magnet. What is the effect? Reverse 

 the ends of the nail. (Be careful that the nail has not become 

 permanently affected by the magnet.) Is the effect the same as 

 when the ends of the magnet were reversed ? 



475 



