Читать книгу The Journey to the Polar Sea - Franklin John - Страница 35

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.

Knee Lake towards its upper end becomes narrower and its rocky shores are broken into conical and rounded eminences, destitute of soil, and of course devoid of trees. We slept at the western extremity of the lake, having come during the day nineteen miles and a half on a South-West course.