TERRESTRIAL MAGNETISM, ETC. 259 



" localities, situated in different parts of the world, 

 >( where the disturbance of the compass has been 

 " noted by trustworthy observers, and I would raise 

 " a note of warning to navigators, prone to shave 

 " corners on a dark night, guiding their ships solely 

 " by the compass, that the rocks they approach 

 " with ample water over them for the ship to float 

 " and be safe, may be so strongly magnetic as to 

 " deflect the compass, carrying the ship into serious 

 " danger if not destruction. 



" Observations tend to show that magnetic rocks 

 " in the northern hemisphere attract the north end 

 " of the needle, and therefore a ship nearing the 

 " land in moderate depths of water, say under 

 " twenty fathoms, on northerly courses, would be 

 " drawn nearer and nearer to them. In the 

 " southern hemisphere the converse appears to 

 " hold good, the north end of the needle being 

 " generally repelled, and a ship steering on 

 " southerly courses might be liable to close the 

 " land without her officers knowing anything about 

 " it. Two well-established examples of disturbing 

 " localities will help to illustrate the foregoing 



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