Page:A Voyage of Discovery and Research in the Southern and Antarctic Regions Vol 1.djvu/417

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Chap. X.]
MEAN TEMPERATURE OF THE OCEAN.
317
1841

we were getting very near to the line of equal temperature throughout its whole depth, which encircles the globe between the fiftieth and sixtieth degree of south latitude. The temperature at 600 fathoms was 39.8: at 450 fathoms, 39.8: at 300 fathoms, 39.5: at 150 fathoms, 39.: and at the surface 38.5: so that no doubt a few weeks earlier we should have here found the mean temperature to prevail, although at this season of the year it was still a short distance to the northward; but we had no opportunity of determining its place more accurately.

During the 30th and 31st we pursued our course March 30, 31.to the north-eastward, favoured by a moderate north-westerly breeze and fine weather. Between the periods of our observations on the evening of the 30th and evening of the 31st we again crossed the line of no variation, and having been fortunate in getting numerous azimuths, the point where we passed over it may be deduced with great exactness.[1] The Aurora appeared in great brilliancy during the night of the 30th; its various phases are minutely noted in the Log-book, and will be found of great value whenever the reduction of the magnetometrical observations at Van Diemen's Land shall be proceeded with. A few icebergs were seen, but not in sufficient numbers to give us any uneasiness.

Just before midnight of the 31st the wind shifted to the S.W., and we made all sail before it.

  1. See Table of Observations, page 310 of this Volume.