1890.] Relations between the Hills and Plains of Northern India. 15 



The following table gives the average humidity of the month of 

 January at the same pairs of stations. 



Names of pau's of stations. 



Quetta 



Jacobabad ... 

 Murree 



Eawalpindi ... 

 Simla 

 Lndhiana 

 Chakrata 

 Roorkee 

 Ranikhet 

 Bareilly 

 Darjeeling ... 

 Dbubri 



Mount Abu ... 

 Deesa 



Pacbmarlii . . . 

 Jubbulpore ... 



::.} 



::} 



Mean relative humidity 

 in January. 



Ratio of average 

 humidity of hill 

 station to that of 



Hill 



station. 



A. 



Plain 



station. 



B. 



plain station. 



A. 

 B. 



67 



47 



1-4 



59 



73 



0-8 



61 



68 



0-9 



63 



65 



10 



63 



67 



0-9 



79 



77 



10 



40 



38 



10 



54 



60 



11 



These tables show that while the amount of cloud is considerably 

 greater at the hill-stations that at the plain stations in Upper India, the 

 air is actually on the average drier or less humid in the former case. As 

 these results are based on day observations chiefly, it is probable if night 

 observations of equal weight were included the difference would be even 

 more marked. 



The following is a brief general summary of the mean temperature 

 conditions at the level of the hill stations in the Himalayas and on the 

 adjacent plains. 



(1.) The rate of decrease with elevation of the average daily tem- 

 perature of the month of January is very approximately 2^° per 1,000 feet 

 or more exactly 1° per 470 feet. The rate of decrease is, however, very irre- 

 gular, varying not only from day to day but also from hour to hour 

 during the day. The rate of decrease of the average minimum or night 

 temperature with elevation in Upper India is only about 1^° per 1,000 

 feet and of the average maximum temperature is 3° per 1,000 feet. 



(2.) The daily range of temperature is much less at the hill 

 stations than in the adjacent plain districts and is little more than half 

 that at the adjacent plain stations. 



It also follows from the previous remarks that any explanation of the 



