1841.
600 fathoms it was 44°·9; at 450 fathoms, 46°·8; at 300 fathoms, 49°·2; at 150 fathoms, 53°·5; and at the surface, 58°; the specific gravity of the surface water, 1·0274; at 150 fathoms, 1·0272, and at 450 fathoms, 1·0268; all tried at the temperature of 60°, and showing that the water beneath was specifically lighter than that of the surface, when brought to the same temperature; our almost daily experiments confirmed these results.
Soon afterwards a breeze sprang up from the northward; heavy showers of rain, and a falling barometer, as usual accompanied the northerly wind; but what surprised us was, that the temperature of the air fell in the course of two hours from 63° to 54°; that of the surface of the sea not being altered by the change of wind. It is probable that this effect was produced by the rain having fallen from a great elevation, and therefore of a very low temperature; but it was unfortunately omitted to be noted.
At eight in the evening of the 29th, we were Nov. 29. only fifty miles distant from the Sister Islets, and a reef of rocks which lies about six leagues to the northward of Chatham Island; but as the night was fine and the wind favourable, we continued our course for its N. W. point, named Point Allison, heaving to occasionally to try for soundings, as we approached these dangerous and almost unknown shores.
Thick weather came on during the night, which rendered these precautions the more necessary.