TERRESTRIAL MAGNETISM, ETC. 261 



Captain Wharton, in the discussion following 

 the reading of this paper, said : 



" Captain Creak has brought forward the ques- 

 " tion of the disturbance of the compass on 

 " approaching shore. For a long time it was 

 " thought not possible that the compass could 

 " really be disturbed. By well-known magnetic 

 " laws the sphere of influence of any disturbing 

 " forces is so small that it was thought quite im- 

 " possible that the compass passing a point of 

 " land should ever be disturbed by the magnetic 

 " character of the rock. But in some extraordinary 

 " manner it has been overlooked, that while a ship 

 " is a long distance horizontally from land, she 

 " may be passing very closely vertically over it 

 " in shallow water, and it has only been recently 

 " recognised that this is the true explanation, and 

 " that there really is a danger in certain places, the 

 " majority of which are quite unknown, in passing 

 " over shallow water, of the compass being seriously 

 " deflected. I believe now that it is known it will 

 " be borne in mind." 



The statement regarding the Meda's observation 



