THE RATE OF DECREASE OF TEMPERATURE, ETC. 95 



I. Stations beyond the Belt. 



Winter ratio. Summer ratio. 



Allenheads and Bywell ^J^ =178 ^ili =1-37 



13-40 15-50 



Great St. Bernard and Geneva ^^'^^^ = r%o ^^'^^^ = 1-21 



1 7.-207 19-406 



Dodabettaandmeanof Madras and "1 27*200 ., 57*520 



I^ombay J 76^^^^^" "^ ^8^^^^ 



At all these stations, therefore, the ratio is greater in 

 the winter than in the summer half of the year. 



2. Stations in the Belt. 



Winter ratio. Summer ratio. 



Madrid and Lisbon -AJ — =0-235 • =Q'559 



23-453 7-228 



Alagir and Koutais -2 — ? = o-275 — -^^=1-16 



33*426 24-518 



Alexandropol and Lenkoran ^ ^^^ =0- 1 go ^ ° ^=o' q -? 6 



31-196 ^ 18-285 



We see, then, that at stations within the belt the ratio 

 is greatest in the summer half of the year; and it would 

 therefore appear that at these stations the quantity of rain- 

 forming moisture in the higher strata of the air, as compared 

 with that in the lower, is relatively greater in the summer 

 than in the winter half of the year; while, on the con- 

 trary, at stations beyond the belt it is greatest in the winter 

 half. 



Before concluding this paper, I may take the opportunity 

 of drawing attention to some results which appear to 

 indicate a periodical change in the annual value of the 

 rate of decrease of temperature for a given ascent in the 

 atmosphere. In the following Table I have given the 

 mean annual temperatures, and the differences, for the 

 two stations Geneva and the Hospice on the Great St. 

 Bernard, for the years 1848-1858 : — 



