OF A NORTH-WEST PASSAGE. 



421 



stant darkness to constant day ; and this is of course the more sudden and 

 striking in proportion to the height of the latitude. Even in this compara- 

 tively low parallel the change seemed sufficiently remarkable ; for soon after 

 the middle of March, only ten weeks after the sun's re-appearance above 

 the horizon, a bright twilight appeared at midnight in the northern heavens. 



The annexed abstract contains a comparative view of the mean tempera- 

 ture of the atmosphere during six months of each of the three winters passed 

 in the polar regions, by this and the preceding Expedition. 





Mean temperature of the Atmosphere at 





Months. 



— — — — . __ 



Melville Island, 

 lat. 74fO, 

 1819-20. 



Igloolik, 

 lat. 69\°, 

 1822-23- 



Winter Island, 

 lat. 66{°, 

 1821-22. 



REMARKS. 



October . . . 

 November 



December . . . 

 January- 

 February 

 March 



O 



— 3.46 

 -20.60 

 -21.79 



30.09 

 -32.19 



- 18.10 



■+ 12.79 



- 19.37 



- 27.80 



- 17.07 

 -20.41 



- 19.75 



, O 

 + 12.51 



+ 7.75 



- 12.94 



- 22.96 



- 24.97 



- 11.64 



The " corrected temperature" in the 

 lower line of each column of this 

 Table is the " registered temperature" 

 with a deduction of 3° for the warm 

 atmosphere of the ship. 



Mean registered temperature 



-21.04 



- 15.27 



.~ 8 - 71 





Mean corrected temperature 



_ 24 



— 18.3 



- 11.7 





