Thoughts on Magndifm. 93 



from the deepeft receffes with which we are acquainted contain from 15 to 20 or 25 percent, 

 of iron in the ftate moft favourable to magnetic attra£bion. 



Taking then this aflcrtlon to be as fully proved as its fubjecfl matter is capable of being 

 afcertained, we may deduce from it the following corollaries : 



I ft. That as the ferruginous matter in the globe being by far the moft copious, its 

 univerfal attraftive power is principally feated in the ferruginous part. •; 



2d. That as all terraqueous matter was originally in a foft ftate, its parts were at liberty^ 

 to arrange themfelves according to the laws of their mutual attraction, and in fa£t did coa- 

 lefce and cryftalize in the direflion in which they were leaft impeded by the rotatory motion 

 of the globe, namely in that which extends from North to South, and principally and moft 

 perfectly in the parts leaft agitated by that motion, namely thofe next the centrct 



3d. That this cryftallzation, like that of falts, might have taken place in one or more 

 feparatey&oo//j or as we may here call them, immenfe feparate mafles, each having its poles 

 di£tin£t from thofe of the other, thofe in the fame direction repulfive of and diftant from 

 each other. 



In confequence then of the univerfal law of attraction of the particles of matter to each 

 other, thefe internal magnets exert a double power of attraction ; the firft and moft general, 

 on the particles of all bodies indifcriminately in proportion to their denfity, and the direCt 

 or inverfe ratio of the fquares of their diftances according as thofe bodies are found within 

 or without the earth's furface ; and the fecond, on bodies of their own fpecies in proportion 

 to their homogenity, and to the correfpondence of the arrangement of their integrant 

 particles with that of the integrant particles of thefe internal magnets. 



A magnet therefore is a mafs of iron, or of iron ore, whofe oxygenation does not exceed' 

 20 per cent, or thereabouts, whofe particles are arranged in a direction fimilar to that of the 

 great internal central magnets of the globe. This I call the magnetic arrangement. 



The particles of iron attraCt each other more forcibly than thofe of any other known 

 fubftance. This appears by its cohefion, hardnefs, elafticity, and infufibility, in each of 

 which properties, or at leaft in the combination of moft of them, it exceeds all other known 

 bodies. 



Hence a magnet attradls iron when within the fphere of its action, by forcing, in virtue 

 of its attractive power, a certain proportion of its integrant particles into a difpofition and 

 arrangement fimilar to that of its own. For in this cafe it exerts a double attractive power, 

 that of the particles of iron to each other, which we have feen to be the greateft of all othersj 

 and that of cryftalizing bodies, which we have alfo feen to be indefinitely great. 



The cryftalizing power being at once attractive and repulfive, according to the direCtion 

 of the furfaces, (No. 6.) hence we fee that one part or end of the magnet muft repel that 

 which the other has attracted, as long as the fame difpofition of parts remains. 



The difpofition of parts in a particular magnet, being fimilar to that which obtains in the 

 great internal general magnet, extends in the direction of from North to South. Hence 



magnets,, 



