260 POPULAR LECTURES AND ADDRESSES. 



" remarks, which are the outcome of considerable 

 " inquiry. 



" The first is the case of our surveying vessel 

 " Meda, at Cossack, in North Australia. Here, 

 " with the visible land three miles off, the Meda, 

 " in eight fathoms of water, running on a line of 

 " two objects on shore, had her compass steadily 

 " deflected 30 for a quarter of an hour during 

 " which she sailed over half a mile. 



" The next instance is that furnished by observa- 

 " tions of the variation of the compass on the east 

 " coast of Madagascar. The normal lines of the 

 " variation for several miles of the coast from St. 

 " Mary's Isle southward should be from about 

 " 11 W. to 12 W.; but instead of this the French 

 " men-of-war, which are frequently running up and 

 " down this part of the coast, find that the varia- 

 " tion near the shore at St. Mary's Isle is only 6 

 " or 7 W. and 12 W. at 80' South : the north end 

 " of the compass being repelled by the magnetic 

 " properties of the bottom. These results are 

 " analogous with those of observations on shore 

 " in Madagascar, New Zealand, and other places." 



