36 A JOURNEY TO THE SHORES 



About half a mile from the bend or knee of the lake, there is a small 

 rocky islet, composed of magnetic iron ore, which affects the mag- 

 netic needle at a considerable distance. Having received previous 

 information respecting this circumstance, we watched our compasses 

 carefully, and perceived that they were affected at the distance of 

 three hundred yards, both on the approach to and departure from the 

 rock : on decreasing the distance, they became gradually more and 

 more unsteady, and on landing they were rendered quite useless ; and 

 it was evident that the general magnetic influence was totally over- 

 powered by the local attraction of the ore. When Kater's compass 

 was held near to the ground on the N.W. side of the island, the 

 needle dipped so much that the card could not be made to traverse 

 by any adjustment of the hand ; but on moving the same compass 

 about thirty yards to the west part of the islet, the needle became 

 horizontal, traversed freely, and pointed to the magnetic north. The 

 dipping needle being landed on the S.W. point of the islet, was 

 adjusted as nearly as possible on the magnetic meridian by the sun's 

 bearings, and found to vibrate freely, when the face of the instru- 

 ment was directed to the east or west. The mean dip it gave was 

 80° 37' 50". When the instrument was removed from the N.W. to 

 the S.E. point, about twenty yards distant, and placed on the meri- 

 dian, the needle ceased to traverse, but remained steady at an angle 

 of 60°. On changing the face of the instrument, so as to give a S.E, 

 and N.W. direction to the needle, it hung vertically. The position 

 of the slaty strata of the magnetic ore is also vertical. Their direc- 

 tion is extremely irregular, being much contorted. 



Knee Lake towards its upper end becomes narrower, and its rocky 

 shores are broken into conical and rounded eminences, destitute of 



and of course devoid of trees. We slept at the western extre- 

 mity of the lake, having come during the day nineteen miles and a 

 half on a S.W. course. 



We began the ascent of Trout Kiver early in the morning of the 



