RECAPITULATION. 465 



5. When two magnets approach each other, 

 their poles of the same names, that is, both their 

 north poles, or both their south poles, repel each 

 other 



6. But poles of different names attract each 

 other. 



7. The earth itself appears to be a great 

 magnet, having its poles near to, but not coincid- 

 ing with the ends of the imaginary axis, on which 

 it turns. 



8. Its poles act upon every small magnet at- 

 tracting its contrary pole. 



9. From this theory the dip, or inclination of a 

 magnet to the plane of the horizon is easily ex- 

 plained. 



10. The deviation of the direction of a magnet 

 from due north and south, is owing to the situation 

 of the magnetic poles of the earth, and is called 

 the declination of the magnet. 



11. The magnetic poles of the earth are not 

 stationary, but are continually changing their 

 places. 



12. This occasions a constant change of the 

 declination, and this is called the variation of the 

 compass. 



13. The loadstone is an iron ore naturally pos- 

 sessing magnetism. 



14. Magnetism, may be communicated to iron 

 and steel. 



1.5. Pure iron most easily receives magnetism, 

 but loses it immediately. 



16. Iron combined with carbon, as hard iron or 

 steel, retains the magnetic properties when com- 

 municated to it. 



17- A steel bar rendered magnetic, and fitted 



vol. 1. h H 



