296 SCIENCE OF COMMON THINGS. 



Bodies capable of being magnetized. Induction. Magnetic needle. 



1014 What bodies are capable of being magnetized by contact with 

 natural magnets ? 



Iron and steel are the substances most susceptible of 

 tins influence, but brass, nickel, and cobalt can also 

 become magnets. 



1015 Does the magnetism imparted to a piece of soft iron, or steel, by 

 contact with a natural magnet, remain permanent in their substances f 



In the steel it does^ but the soft iron loses its power as 

 soon as it is removed from the magnet. 



1016 Is it necessary that absolute contact should take. place between a 

 magnet and a pwcu of soft iron to render the latter a magnet 1 



No, every piece of soft iron brought near a magnet 

 becomes by induction itself a magnet. 



IS*!*? What dc you mean by induction ? 



It is the production of like effects in contiguous bo- 

 iifs. In electricity or magnetism, it is the influence 

 exerted by an electrified or magnetized body through 

 a non-conducting medium without any apparent com- 

 munication of a current. 



1018 What is meant by the directive power of the magnet f 



It is that power which will cause a magnet, when 

 suspended freely, to constantly turn the same part to- 

 wards the north pole and the opposite part towards the 

 south pole of the earth. 



1010 What are the poles of a magnet f 



They are the ends of the magnet, and are denomi- 

 nated north and south poles, according as they point to 

 the north or south poles of the earth. 



103O What are the poles of the earth ? 



The extremities of the earths axis, or the points on 

 the surface of the globe through which the axis passes. 



1031 What is a magnetic needle ? 



Simply a bar of steel which is a 

 magnet, suspended in such a way 

 that it can freely turn to the north 

 or south. 



1033 What is a mariner's compass f 



It is a delicate steel lar or 



Jig. 92- 



