380 APPENDIX II 



again, is dependent on the degree of humidity of the air. (See 

 the diagrams.) These instruments have been in use in Norway for 

 several years, especially at inland stations, where the winter is 

 very cold, and they have shown themselves superior to all others in 

 accuracy and durability; but there was no one ©n the Fram who 

 knew anything about them, and there is therefore a possibility 

 that they were not always in such good order as could be wished. 

 On September 10, especially, the variations are very remarkable; 

 but on October 13 the second instrument, No. 12, was hung out, 

 and there can be no doubt of the correctness of the subsequent 

 observations. 



It is seen that the relative humidity attains its maximum in 

 winter, in the months of July and August, with a mean of 90 per 

 cent. The driest air occurs in the spring month of November, 

 with a mean of 73 per cent. The remaining months vary between 

 79 and 86 per cent., and the mean of the whole ten months is 

 82 per cent. The variations quoted must be regarded as very 

 small. On the other hand, the figures themselves are very high, 

 when the low temperatures are considered, and this is doubtless 

 the result of there being open water not very far away. The 

 daily course of humidity is contrary to the course of the tempera- 

 ture, and does not show itself very markedly, except in January. 



The absolute humidity, or partial pressure of aqueous vapour in 

 the air, expressed in millimetres in the height of the mercury in the 

 same way as the pressure of the atmosphere, follows in the main 

 the temperature of the air. The mean value for the whole period 

 is only 08 millimetre (0'031 inch); December has the highest 

 monthly mean with 2*5 millimetres (0'097 inch), August the 

 lowest with 01 millimetre (0'004 inch). The absolutely highest 

 observation occurred on December 5 with 4 "4 millimetres (0'173 

 inch), while the lowest of all is less than 0'05 milHmetre, and 

 can therefore only be expressed by O'O; it occurred frequently in 

 the course of the winter. 



