anfc nature of dfcagnetfsm. 35 



can move freely, and pass a current of elec- 

 tricity through it, the helix will arrange itself 

 north and south the same as a magnetic needle. 

 Its attractive properties are feeble in com- 

 parison with that of the iron, but it obeys the 

 laws of a magnet. The earth is probably a 

 magnet of this kind, consisting mostly of lines 

 of force. 



However, the iron in the earth is affected 

 magnetically, as we have evidence in the load- 

 stone. The earth has the power also to mag- 

 netize iron through the medium of its mag- 

 netic field, that reaches out in lines of force 

 from pole to pole like those of the artificial 

 magnet. If we hold a bar of iron in line with 

 the magnetic axis of the earth and dip it in 

 line with the dipping needle and then strike it 

 a few blows on the end, it will be found to be 

 feebly magnetic. The blows have partly 

 loosened the molecules and during the moment 

 that they unclasped themselves the earth's 

 magnetism has through its lines of force 

 caught them for a time and held them a little 

 out of their natural position as they are in a 

 state of rest. The peculiar changing light 

 that we sometimes see in the northern sky, 

 tluit is railed the Aurora Borealis (Northern 

 Li.L'lii ). is indirectly duo to intense magnetic 

 lines of force that radiate from the north mag- 

 netic polo of the earth. Those lines of force 

 are able to cause the rarified air molecules to 



