XI.] MILD WEATHER FOLLOWED BY SEVERE COLD. 399 



women, and children. Many passed here the greater part of 

 the day, cheerful and gay in a temperature of —40° C, gossiped, 

 helped a little, but always only a little, at the work on board, 

 and so on. The mild weather, the prospect of our getting free, 

 and of an abundant fishing for the Chukches, however, soon 

 ceased. The temperature again sank below the freezing-point, 

 that is of mercury, and the sea froze so far out from the shore 

 that the Chukches could no longer carry on any fishing. Instead 

 we saw them one morning come marching, like prisoners on an 

 Egyptian or Assyrian monument, in goose-march over the ice 

 toward the vessel, each with a burden on his shoulder, of whose 

 true nature, while they were at a distance, we endeavoured in 

 vain to form a guess. It was pieces of ice, not particularly 

 large, which they, self-satisfied, cheerful and happy at their new 

 hit, handed over to the cook to get from him in return some of 

 the kaulri (food) they some days before had despised. 



The first time the temperature of the air sank under the 

 freezing-point of mercury, was in January. It now became 

 necessary to use instead of the mercury the spirit thermometers, 

 which in expectation of the severe cold had been long ago hung 

 up in the thermometer case. When mercury freezes in a 

 common thermometer, it contracts so much that the column of 

 mercury suddenly sinks in the tube, or if it is short, goes wholly 

 into the ball. The position of the column is therefore no 

 measure of the actual degree of cold when the freezing takes 

 place. The reading of —89°, or even of —150°, which at a 

 time when it was not yet known that mercury could at a low 

 temperature assume the solid furm, was made on a mercurial 

 thermometer in the north of Sweden,^ and which at the time 

 occasioned various discussions and doubts as to the trustworthi- 

 ness of the observer, was certainly quite correct, and may be 

 repeated at any time by cooling mercury under its freezing-point 

 in a thermometer of sufficient length divided into degrees under 

 0°. The freezing of mercury - takes place from below upwards, 



1 And. Hellant, Arnndrhninrjar om en lielt ovanliq hold i Tome {Remarks 

 on a Quite Unusual Cold in Tome), Vet.akad. Handl. 1759, p. 314, and 

 1760, p. 312. In the latter paper Hellant himself sho\vs that the oolimin 

 of mercury in a strongly cooled thermometer for a few moments sinks 

 farther when the ball is rapidly heated. This is caused by the expansion 

 of the glass when it is warmed before the heat has had time to com- 

 municate itself to the quicksilver in the ball, and therefore of course can 

 happen only at a temperature above the freezing-point of mercury. 



^ That mercury solidifies in cold was discovered by some academicians 

 in St. Petersburg on the 25th December, 1759, and caused at the time a 

 great sensation, because by tliis discovery various erroneous ideas were 

 rooted out which the chemists had inherited from the alchemists, and 

 which were based on the supposed property of mercury of being at the 

 same time a metal and a fluid. 



