MAGNETS AND THEIR PROPERTIES 



345 



Electricity in the home. Your father and mother can 

 doubtless remember the first time they saw the trolley car 

 or the incandescent light ; it was only a few years ago that 

 the wireless was first used. So we see that the harnessing 

 of this great power, electricity, has been comparatively 

 recent, and that we are just at the beginning of an era of 

 electricity and electrical devices. Modern households, 

 if well equipped, may have many of these labor saving and 

 useful instruments. There are three general types of elec- 

 tric devices. Examples of them are the electric door- 

 bell, the motor which drives the machine, and the elec- 

 tric iron. The bell and the motor depend upon electro- 

 magnetic action to do their work, while the iron depends 

 upon the heating effect of the electric current. In order 

 to understand even a little about these devices, it is neces- 

 sary for us to know something of the properties of elec- 

 tricity, particularly in its relation to magnetism. Every 

 boy and girl has 

 played with a magnet 

 or some toy in which 

 a magnet was used 

 and yet may not know 

 just what a magnet 

 is. 



Magnets and their 

 properties. A great The magnetic strength is greatest near the ends> 

 many years ago, iron ore was found in Magnesia, Asia Minor, 

 which had the property of attracting to it other pieces of 

 iron. This ore was called magnetite, and the name magnet 

 was thus derived from the name of the country in which it 

 was first found. We can make artificial magnets, either by 

 rubbing a piece of steel with a natural magnet, or by hold- 



