The temperature of the atmosphere having about this time become considerably lower than before, the cracking of the timbers was very frequent and loud for a time; but generally ceased altogether in an hour or two after this fall had taken place in the thermometer, and did not occur again at the same temperature during the winter. The wind blowing fresh from the northward, with a heavy snowdrift, made the ship very cold below; so that the breath and other vapour accumulated during the night in the bed places and upon the beams, and then immediately froze; hence it often occupied all hands for two or three hours during the day to scrape the ice away, in order to prevent the bedding from becoming wet by the increase of temperature occasioned by the fires. It was therefore found necessary to keep some of the fires in between decks at night, when the thermometer was below -15° or -20° in the open air, especially when the wind was high. To assist in keeping the lower decks warm, as well as to retard, in some slight degree, the formation of ice immediately in contact with the ships' bends, we banked the snow up against their sides as high as the main chains; and canvass screens were nailed round all the hatchways on the lower deck. The stars of the second magnitude in Ursa Major were just perceptible to the naked eye a little after noon this day, and the Aurora Borealis appeared faintly in the southwest at night. About this time our medical gentlemen began to remark the extreme difficulty with which sores of every kind healed; a circumstance that rendered it the more necessary to be cautious in exposing the men to frostbites, lest the long inactivity and want of exercise during the cure of sores, in other respects trifling, should produce serious effects upon the general health of the patients. During the following fortnight we were chiefly occupied in observing various phenomena in the heavens, the vivid coruscations of the Aurora Borealis, the falling of meteors, and in taking lunar distances; but the difficulty of making observations in this climate is inconceivably great; on one occasion the mercury of the artificial horizon froze into a solid mass. About this part of the winter we began to experience a more serious inconvenience from the bursting of the lemon-juice bottles by frost, the whole contents being frequently frozen into a solid mass, except a small portion of highly concentrated acid in the centre, which in most instances was found to have leaked out, so that when the ice was thawed it was little better than water. This evil increased to a very alarming degree in the course of the winter: some cases being opened in which more than two thirds of the lemon-juice was thus destroyed, and the remainder rendered nearly inefficient.