MODE VI. SERPENTINE. 343 



about Mount Rosa are owing to a peculiar and 

 local circumstance. 



" One of the most remarkable hills of serpen- Magnetic 



Dill* 



tine, on account of the phenomena which it pre- 

 sents, is that observed by Humboldt, in 1793, in 

 the chain of mountains which separates the mar- 

 graviate of Bareith from the Upper Palatinate. 



" This hill is only elevated fifty fathoms above 

 the neighbouring plains: it extends in length 

 from east to west, its skirts consequently are to 

 the north and south. 



" The rocks which crown its summit are of a 

 very pure serpentine, which, by its colour and 

 foliated fracture, approaches schistose chlorite. 

 It is divided into tolerably distinct beds, and re- 

 poses on a veined granite, mixed with horn- 

 blende. 



" Humboldt having brought his compass near 

 these rocks of serpentine, saw with surprise, that 

 the north pole flew round quickly to the south. 

 He farther observed, that the rocks of the north 

 declivity, and those of the southern, have their 

 poles directly contrary. In the former are only 

 found south poles, and in the latter north poles. 

 The eastern and western extremities of the hill 

 are in a state of indifference, and do not mani- 

 fest any action on the magnetic needle, though 

 otherwise the rock affords the same appearance. 



