10 Jolin Eliot — On the occasional Inversion of the Temperature [No. 1, 



The differences here are small and to some extent undoubtedly depend 

 upon the peculiarities of position of the observatories at the observing 

 stations, Their general uniformity, however, appears to indicate clearly 

 that the lowest minimum temperatures in January in the great Nor- 

 thern or Gangetic plain of India are not found at and near the foot 

 of the hills, but in the midst of the great plain at a distance of 100 to 

 200 miles from the Himalayas, or, as it might be more fully expressed, 

 the axis of minimum or lowest night temperature in Northern 

 India in the month of January runs nearly parallel to the Himalaya 

 mountains at a distance from their southern base varying from 100 to 

 200 miles. This fact seems to be of great importance as it shews that, 

 whatever the rapid cooling in these plains may be due to, it cannot 

 be ascribed to the cause usually assigned for the greater cold in valleys 

 than in hill sides, viz., the sinking of air cooled by contact with the 

 sides of the hills into the valleys. For it is not possible that the 

 cooled air sinking down with a motion which is imperceptible to 

 the anemometer or senses should produce the greatest effects at 

 distance of one or two hundred miles from the foot of the hills and 

 where the temperature is higher by day, as is shewn by the following 

 table : — 





a c^ 





a ^ 



^i-g 



© 





lo 





1-9 



2 5 § 



rQ 







a © 



S © 









Plain stations 





etween 

 are for 

 ons of 



-A.) 





Plain stations 



Mean 

 tempe 

 nuary 



at consider- 



Mean 

 tempe 

 nuary 



'^ ""i 



near hills. 



able distance 

 from hills. 



oil a 













fH a o .^ 



N 2^ 





(A.) 





(B.) 



s 



o += 



Rawalpindi 



63-3° 



Peshawar 



64 0° 



7° 



100 m 



lies 



Sialkot 



66 7° 



Lahore 



67-6° 



0-9° 



75 





Lndhiana 



67-6° 



Sirsa 



70-8° 



3-2° 



100 





Eoorkee 



694° 



Meerut 



70-1° 



0-7° 



60 









C Delhi 



710° 



0-9° 



90 





Bareilly 



70-1° 



I Agra 



73-4° 



3-3° 



120 









C Lucknow 



73-8° 



37° 



125 





Gorakhpur 



73-4° 



f Allahabad 

 1 Benares 



73-6° 



74-7° 



0-2° 

 1-3° 



125 



100 





Dhubri 



73-4° 



Berhampore 



78-2° 



4-8° 



150 





The following table gives mean daily temperature (^^ e., means of the 

 maximum and minimum temperatures) data of the month of January for 

 the same pairs of stations : — 



