467 



between 40 and 60 S. Lat. is certainly higher in the winter than in the corresponding part of the 

 northern hemisphere, and this may tend to prevent the occurrence of such low temperatures at the South 

 as at the North Pole. Possibly, however, a greater supply of heat from the tropics may be carried by the 

 upper currents to the south, but we are as yet so entirely ignorant of the movement of the layers of air 

 which lie above the cirrus, that is to say roughly of half the atmosphere, that speculation on the subject 

 is useless. 



DAILY TEMPERATURE CURVES. 



Professor MOHN, discussing the results obtained by the voyage of the "Fram," finds during the dark 

 months in the Arctic circle a daily variation of temperature. It is of course obvious that, since the sun 

 is far below the horizon, the effect must be an indirect one, and he considers that it is due to a diurnal 

 change in the direction of the wind. Dr. CHKEE has discussed the question with reference to the 

 observations made by the " Discovery," but the matter is one of considerable interest, and hence I trust 

 I may bo pardoned for going over somewhat the same ground, and I have drawn the curves of fig. 2. 



6A.M. 



Noon 



6P.M. 



January 



February 



March 



April 



May 



June 



6A.M. Noon 



6P.M. 



January 



February 



July 



August 



March September 



April 



May 



June 



October 



November 



December 



July 



August 



September 



October 



November 



December 



6A.M. Noon 



Vertical Scale 



6P.M. 

 in. to 8F. 



6A.M. Noon 6P.M. 



Vertical Scale %in. fco 8F. 



Fig. 2. 



The amount of material hardly suffices to make these curves trustworthy, especially when the very rapid 

 changes of temperature which the figures, and more particularly the self-recording instruments, show 

 are taken into account. This is fairly obvious when we compare the daily course of the temperature in 

 August, 1902, with a variation of barely I" F., with that of August, 1903, showing a difference of 3 F. 

 between 8 a.m. and 8 p.m. In the sunny months the oscillation is perfectly clear and distinct, although 

 the amplitude is small, being less than 5 F. for January, 1902, the month in which it is most marked. 

 The warmest time in summer appears to be about 4 p.m., but the number of observations only allows 



3 O 2 



