MAGNETISM. 99 



CHAPTER IV. 



ELECTRICITY AND MAGXETISM. 

 237. NATIVE MAGNETS. The native mag- 



What proper- 

 ties has the na- net, or loadstone, is a mineral which has 



tive magnet? the remar j c able property of attracting me- 

 tallic iron to itself, and of taking north and south di- 

 rection, when suspended and free to move. Particles 

 of iron brought near, rush toward it, and remain at- 

 tached to its surface, without any visible cause. It ex- 

 erts this attractive force just as well through wood, 

 stone, or any other material, as through the air. 



23$. ARTIFICIAL MAGNET. The same 



Describe an . 1-1 



artificial mag- properties may be imparted to a piece of 

 steel, by a process to be hereafter described. 

 Such a piece of steel thereby becomes itself 

 a magnet. Magnets are often made of a shape 

 approaching that of a horse-shoe, the two 

 poles being brought near to each other. A 

 piece of soft iron, called an armature, is placed across 

 the end to prevent the loss of magnetic power, which is 

 found otherwise to occur. 



239. MAGNETIC NEEDLE. If a steel bar 



What is the 



magnetic nee- be made into a magnet, and then balanced 

 on a pivot, it will turn, until one end points 

 north and the other south. That which ^ 

 moves toward the north is called the north 

 pole, and the other end the south pole. 

 A small bar thus balanced is called a mag- 



