158 



lower strata of the atmosphere; while, on the contrary, at 

 places'north or south of the belt the changes of temperature 

 are greatest in the lower strata. The details of the results 

 are given in the Paper, and all the temperatures are reduced 

 to Fahrenheit's scale, and the differences of elevation to 

 English feet. 



The great changes of temperature which take place in the 

 higher strata of the atmosphere in the belt, indicate a less 

 capacity for heat and a greater degree of dryness of the air in 

 these strata than in the corresponding strata beyond the belt. 

 The Author was therefore led to conclude that the ratios of 

 the quantities of rain falling on the mountain and on the 

 plain would be less at places in the belt than in other locali - 

 ties ; and the results which he has given of the comparisons 

 of the mean annual amounts of rain-fall at different stations 

 fully bear out this conclusion. Comparisons are also made 

 of the falls of rain during the winter and summer halves of 

 the year ; and it is shown that at places in the belt the ratio 

 of the quantity falling on the mountain to that falling on the 

 plain is greater in the summer than in the winter half of the 

 year, while on the contrary, at places beyond the belt, it is 

 greatest in the winter half. 



The Author then draws attention to some results which 

 appear to indicate that the annual rate of decrease of tempe- 

 rature, on ascending in the atmosphere, is subject to a 

 periodical change. Comparing Geneva and Milan with the 

 Great St. Bernard, the annual rate for the years 1848 — 58 

 exhibits, with but trifling irregularities, a gradual increase 

 up to the beginning of the year 1854, and afterwards a 

 o-radual decrease. The differences of temperature between 

 the two stations By well and Allenheads, in Northumberland, 

 at a difference of elevation of 12T3 feet, also show a progres- 

 sive increase from 4*14° in 1856, to 0-07° in 1860. The 

 Author remarks that the epoch when the rate of decrease was 

 at a maximum, as shown by the Geneva and Great St. Ber- 



