1890.] Relations lehveen the Hills and Plains of Northern India. 5 



and was the subject of numerous investigations. Hann, in his paper on 

 Die Temperatur Verhaltnisse des Decembers 1879, investigated the 

 matter very thoroughly. He made in that paper a comparison between 

 the temperature of Klagenfurth (in the valley) and Hochober (at an 

 elevation of 5215 ft. above Klagenfurth), and states that from December 

 6th to 18th it was continually warmer on the mountain than in the 

 valley. The mean difference of the 7 A. M. temperatures for these thirteen 

 days was 23'4° in favour of the mountain, at 2 p. m. 212°, and at 9 P. M. 

 19'6° F. Other examples are given in the same memoir of the abnormal 

 vertical temperature conditions which occasionally obtain in Europe and 

 America. Buchan, in a paper published in the Journal of the Scottish 

 Meteorological Society, states that on the 31st December 1883 the tem- 

 perature at the top of Ben Nevis was 4'5° higher than at Fort "William. 

 In this case too pressure was abnormally high. Woeikoff, the Director 

 of the Russian Meteorological Department, on the strength of certain 

 evidence, believes there is a persistent inversion of temperature during 

 the winter in Siberia. Inversion of temperature is also said to be of 

 common occurrence on Mount Washington (in Massachusetts). It is 

 also occasionally shewn by the Pikes' Peak Observations. That moun- 

 tain has an elevation of 14134 feet and is 8,840 feet higher than Denver. 

 Professor Loomis gives 39 examples of higher temperature at the top 

 of Pikes' Peak than at Denver from four years' observations. In the 

 most extreme cases the differences of temperature amounted to 15° and 

 16°. It may be noted that these inversions all occux-red during the 

 winter. 



It is not necessary to quote from the earlier meteorological works 

 of Herschel, Buchan, &c, as they only recognize the occasional oc- 

 currence of lower temperature at night in valleys than on the adjacent 

 hills, and ascribe the effect chiefly to the flow of cold air down the sides 

 of the hills. 



Recent meteorological writings in some cases continue to ascribe the 

 cooling almost entirely to the descent of the air from the mountain sides 

 into the valleys, and state that the inversion of the vertical temperature 

 relations is of comparatively frequent occurrence in mountanous districts. 

 The facts about to be given, however, appear to indicate the probabi- 

 lity that these inverse relations which are exhibited by the mountain 

 observations are due to general conditions that prevail in plains 

 as well as in mountain districts, and hence that similar relations may 

 obtain much more generally and widely than is usually supposed. No 

 distinct statement, however, occurs to this effect, so far as I am aware, 

 and the evidence of inversion of the vertical temperature relations is, in 

 the absence of suitable balloon observations, confined to differences be- 



