162 ONTOLOGY. 



tions of terrestrial magnetism depend upon the nature, 

 character, distribution, number and direction of the 

 metallic veins or beds. 



778. Thus the direction of the magnetic axis of the 

 earth, its mutability, the declination of the magnetic 

 meridian, the inclination or dip of the needle, in short 

 every phenomenon without distinction that concerns 

 magnetism, must be derived from the nature of the 

 metallic veins. Another momentum does not indeed 

 exist for magnetism. 



779. Terrestrial magnetism can only be based upon 

 the polarity of metallic veins, and this upon the ores 

 they contain. It must therefore accommodate itself to 

 the distribution of the chief masses of metals, especially 

 of the idiomagnetic metal. Now it has been ascertained, 

 that the noble metals are accumulated about the equator, 



I such as gold, silver, copper, which may be regarded as 

 ( non-magnetic. In the northern temperate zones, the 

 mountains contain for the most part metals that are non- 

 magnetic and semi-noble, as lead, zinc, antimony, which 

 are usually combined as ores with sulphur. Iron, on 

 I the contrary, being the only magnetic metal, (a fact 

 I which is also determined chiefly by the magnetic needle 

 I in terrestrial magnetism) is accumulated in greater 

 ! quantity towards the north-pole and becomes always 

 rarer in occurrence towards the equator. The southern 

 hemisphere of the earth, is indeed less known in this 

 respect ; but, that towards the south-pole iron rein- 

 creases in quantity, is rendered evident by the magnetic 

 needle when conveyed beyond the equator, inclining to 

 the south-pole. If the cause of the inclination upon the 

 northern hemisphere be sought for in the presence of 

 iron, the same must be done in regard to the southern. 

 The arrangement of the metallic groups from north- to 

 south-pole is thus; iron, lead, silver, lead, iron. 



780. Iron has been deposited at both poles and this 

 in accordance with the genesis of metals, for iron is a 

 half reduced metal, and must consequently be subjected 

 to the demi-action only of light. At or beneath the 



