No. II. 



APPENDIX. 



323 



The mean monthly diurnal fluctuations of temperature in autumn and 

 winter do not exceed 3 ; whereas in spring and summer — the sun then 

 being generally above the horizon — it amounts to 9 . 



Even during mid-winter, when the sun is absent, the diurnal variation 

 does not altogether disappear. 



The effect of the moon during winter, in producing a clear sky and 

 fall of temperature, has long been known. From the observations of the 



1 Fox,' it appears that the temperature is lower at full moon than at new 

 moon by about 7 . 



The effect of a calm is also to lower the temperature. 



At Port Kennedy the most windy months were October and November ; 

 the calmest months were March and April. 



In Baffin's Bay, Februaiy, March, and April, were the most windy 

 months, and June and July the calmest. 



On 30th Sept., 1858, a tube, containing a Thermometer, was sunk 



2 ft. 2 inches into the ground ; the earth for the first six inches was not 

 frozen, but all below that depth had evidently never thawed. In a few 

 days this spot was covered to a depth of 5 ft. with snow, and remained 

 so until the middle of June, 1859. During this period the buried 

 Thermometer indicated the following temperatures : — 



Dates. 



Buried 

 Thermometer. 



1858. 

 13th November 



nth December 



1859. 

 8th January 



1 2th February. 



I Oth March 



7th April . . . 



7th May . . . . 



4th June . . 



Mean Temperature of the Air 



during the seven days preceding 



each observation. 



o 



- I07 



-29-8 



- 36-8 



-34'i 



- 17 



+ 5'9 

 + 26-5 



It may, therefore, be assumed that the earth at that depth reached its 

 minimum temperature — zero — on 1 6th March. 



I subjoin an abstract of the ' Fox ' temperatures ; also one of mean 

 annual temperatures at various stations where arctic expeditions have 



Y 2 



