DECREMENT OF TEMPERATURE, ETC. 133 



perature and other meteorological elements — a branch of 

 meteorology which has hitherto been almost entirely neg- 

 lected, although it seems likely to yield results of consider- 

 able importance to the future progress of the science. 



In the Tables which accompany this paper, the data for 

 mean monthly temperature, rainfall, and amount of baro- 

 metric oscillation are taken from Mr. Vemon^s paper; 

 but the corresponding mean monthly heights of the baro- 

 meter are from the Milan observations, as I had not access 

 to the barometric observations made at Geneva and the 

 Great St. Bernard; this will, however, not affect the 

 general conclusions, as the variations of the barometer at 

 Milan are generally almost precisely similar to those at 

 Geneva. 



Table I. contains the mean monthly and annual results 

 of the comparisons of the rainfall at Geneva and the Great 

 St. Bernard, with the differences of temperature of the two 

 stations. Taking the mean values for the year, we find 

 that an annual rainfall at Geneva of 19*581 in. gives a 

 difference of temperature between the two stations of 

 I9°'47 ; whilst a rainfall of 52*972 in. gives a difference 

 of I9°'89, or o°*4 greater ; and that a rainfall of 26745 in., 

 on the Great St. Bernard gives a difference of 19°' 38, and 

 a fall of 69*838 in. gives a difference of 20°*09, or o°*7i 

 more. It is evident, therefore, that an increase in the 

 amount of rain, either at Geneva or on the Great St. 

 Bernard, is, on the average of the year, accompanied by 

 an increase of the difference of temperature between the 

 two stations. 



Table II. contains all the monthly differences of tempe- 

 rature which are below the mean value, and the correspond- 

 ing falls of rain, mean temperatures, and amounts of baro- 

 metric oscillation, at both stations, and the mean heights 

 of the barometer at Milan. 



Table III. contains all the monthly differences of tem- 



