258 POPULAR LECTURES AND ADDRESSES. 



" The mariner's compass has yet another enemy 

 " to contend with in the magnetic disturbance 

 "caused by proximity to land. This reported 

 " disturbing effect is not now brought forward as a 

 " novelty, in fact it is an old story often told and 

 " discredited by many whose opinions were well 

 " worthy of consideration. Well-authenticated 

 " reports of recent years show that both those 

 " who doubted and those who reported were both 

 " partly right and partly wrong. The facts are 

 " these : it is seldom, if ever, that the visible land 

 " disturbs the compasses of a ship, as her distance 

 " from the shore would almost in every case 

 " entirely keep her out of its magnetic influence. 

 " It is the submerged land near the ship's bottom 

 " which, possessed of magnetic properties, produces 

 " the observed effects, sometimes of attraction, 

 " sometimes of repulsion, on the north point of 

 " the compass. 



" Now, I have brought this part of the subject 

 " forward in order to place a clearly proved fact 

 " on a proper basis, and not with the view of 

 " alarming the seaman. We have now a list of 



