OF A NORTH-WEST PASSAGE. 141 



openings of a ship's inhabited deck into the open air, occurring/rom above, '§21. 

 so that besides the tendency to restore an eqnilibriura occasioned by the 

 rarefaction of the air below, that operation must be much assisted by the 

 comparative specific gravities of the two atmospheres ; the warm by its 

 lightness, constantly struggling to ascend through every open crevice, and 

 the cold by its weight, as incessantly forcing itself downwards. A considera- 

 tion of this circumstance will perhaps set in a still stronger light the value of 

 placing cork or some other slow conductor of heat, as a lining for the deck 

 above, while it also points out the necessity of stopping up as far as practi- 

 cable every hole and cranny communicating with the cold superincumbent 

 atmosphere. On the same account there can be little doubt that, at every 

 opening of our hatchway-doors during the winter, a larger volume of warm 

 air rushed out than would have escaped by a door of equal size, placed below, 

 or on a level with the inhabited deck *. 



The sea presented to-day a large open space to the south-eastward, but 

 the temperature of the atmosphere being low it was almost entirely coated 

 with a sheet of young ice. In some clear pools near the point a single flock of 

 more than fifty dovekies were swimming about, besides other smaller ones. 

 "While continuing the experiments on sound this evening, Mr. Fisher and 

 myself remarked that Sirius, which was nearly on the meridian at the time, 

 exhibited the most beautiful violet and blue colours that can be imagined. 

 The violet was to the wcstAvard, which was the direction in which the moon 

 was, and the Aurora was playing about at the time. 1 thought I had never 

 before seen any thing so brilliant ; the play of prismatic colours in a cut 

 diamond comes the nearest to it. 



The concluding month of this year presented more frequent as well as 

 more brilliant displays of the Aurora Borcalis than we had noticed at an 

 earlier period of the winter. On the evening of the 2d, we observed it 

 constantly appearing, from five till ten o'clock, in one quarter of the heavens 

 or another, but entirely confined to the southern side of the zenith. It 

 consisted sometimes of luminous blotches or small clouds, at others of 

 coruscations shooting upwards, and a stationary light always perceptible 

 near the horizon from S.S.E. to S.AV. The light was white or yellowish 

 white, and the compass was not affected. On the evening of the 3d, it 



* The passage to an Esquimaux hut is in this respect better placed than our doors ; for, 

 being rather below the level of the apartment, the warm air constantly floats above it in the 

 dome of the hut, having no outlet but tlirough the materials of which it is constructed. 



