OF A NORTH-WEST PASSAGE. 



421 



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



•> . . March; 



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 rc-appearancc 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. 



