840 Handbook of Nature-Study 



child, during play time, should have a chance to test the action of the 

 magnets on these objects, and thus be able to answer for himself the ques- 

 tions which should be given a few at a time. 



Observations i. How do we know that an object is a magnet ? How 

 many kinds of magnets do you know? Of what substance are the objects 

 made which the magnets can pick up ? Does a magnet pick up as many iron 

 filings at its middle as at its ends ? What does this show ? 



2 . How far away from a needle must one end of the magnet be before 

 the needle leaps toward it? Does it make any difference in this respect, if 

 the magnet approaches the needle toward the point or along its length? 

 Does this show that the magnetic force extends out beyond the magnet? 

 Does it show that the magnetic force works more strongly where it has 

 more surface to act upon? 



3 . Take a tack and see if it will pick up iron filings or another tack. 

 Place a tack on one end of the magnet, does it pick up iron filings now? 

 What do you think is the reason for this difference in the powers of the tack? 



4. Are some magnets stronger than others? Will some magnets pull 

 the iron filings off from others? In the game of "stealing tacks," which 

 can be played with two magnets, does each end of the magnet work equally 

 well in pulling the tacks away from the other magnet ? 



5. Pick up a tack with a magnet. Hang another tack to this one end 

 to end. How many tacks will it thus hold ? Can you hang more tacks to 

 some magnets than to others? Will the last tack picked up attract iron 

 filings as strongly as the first next to the magnet? Why? Pull off the 

 tack which is next to the magnet. Do the other tacks continue to hold 

 together? Why? Instead of placing the tacks end to end, pick up one 

 tack with the magnet and place others around it. Will it hold more tacks 

 in this way ? Why ? If a magnet is covered with iron filings will it hold as 

 many tacks without dropping the filings? 



6. Take two horseshoe magnets and bring their ends together. Then 

 turn one over and again bring the ends together. Will they cling to each 

 other more or less strongly than before? Bring two ends of two bar mag- 

 nets together; do they hold fast to each other? Change ends with one, 

 now do the two magnets cling more or less closely than before? Does this 

 show that the force in the two ends of a magnet is different in character? 



7. Magnetize a knitting needle or a long sewing needle by rubbing one 

 end of a magnet along its length twelve times, always in the same direction, 

 and not back and forth. Does a needle thus treated pick up iron filings? 

 Why? 



8. Suspend this magnetized needle by a thread from some object 

 where it can swing clear. When it finally rests does it point north and 

 south or east and west? 



9. Bring one end of a bar magnet or of a horseshoe magnet near to the 

 north end of the suspended needle; what happens? Bring the other end 

 of the magnet near the north end of the needle ; what happens ? 



10. Magnetize two needles so that their eyes point in the same direction 

 when they are suspended. Then bring the point of one of these needles 

 toward the eye of the other, what happens? Bring the eye of one toward 

 the eye of the other, what happens ? When a needle is thus magnetized the 

 end which turns toward the north is called the north pole, and the end 

 pointing south is called the south pole. 



