Jack River is only eight miles long but, being full of bad rapids, it detained us considerably.  At seven in the morning of the 24th we crossed the Long Portage where the woods, having caught fire in the summer, were still smoking.  This is a common accident owing to the neglect of the Indians and voyagers in not putting out their fires, and in a dry season the woods may be seen blazing to the extent of many miles.  We afterwards crossed the Second, or Swampy, Portage and in the evening encamped on the Upper Portage, where we were overtaken by an Indian bringing an answer from Governor Williams to a letter I had written to him on the 15th in which he renewed his injunctions to the gentlemen of the boats accompanying us to afford us every assistance in their power.  The Aurora Borealis appeared this evening in form of a bright arch extending across the zenith in a North-West and South-East direction.  The extent of our voyage today was two miles.

Knee lake and magnetic islet.

About noon on the 25th we entered Knee Lake which has a very irregular form and near its middle takes a sudden turn from whence it derives its names.  It is thickly studded with islands and its shores are low and well wooded.  The surrounding country as far as we could see is flat, being destitute even of the moderate elevations which occur near the upper part of Hill River.  The weather was remarkably fine and the setting sun threw the richest tints over the scene that I remember ever to have witnessed.

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 magnetic 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 overpowered by the local attraction of the ore.  When Kater’s compass was held near to the ground on the North-West 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 South-West 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 instrument was directed to the east or west.  The mean dip it gave was 80 degrees 37 minutes 50 seconds.  When the instrument was removed from the North-West to the South-East point about twenty yards distant and placed on the meridian the needle ceased to traverse but remained steady at an angle of 60 degrees.  On changing the face of the instrument so as to give a South-East and North-West direction to the needle it hung vertically.  The position of the slaty strata of the magnetic ore is also vertical.  Their direction is extremely irregular, being much contorted.