10 MR. G. V. VERNON ON THE IRREGULAR BAROMETRIC 



above the average, in the months of January, February, 

 March, April, May, August, September, and November, 

 is accompanied by a larger amount of rain-fall than a 

 number of oscillations below the average. In the months 

 of June, July, October, and December, the converse of 

 this holds good. 



On the mean of the year, a number of oscillations above 

 the average at the Great St. Bernard is accompanied by 

 a larger amount of rain-fall than when the number is 

 below the average. 



We now come to the effect of the rain-faQ. A rain-fall 

 above the average at Geneva, in every month of the year, 

 is accompanied by a larger amount of oscillation than a 

 rain-fall below the average. 



At the Great St. Bernard, a fall of rain above the 

 average, in the months of January, February, March, July, 

 November, and December, is accompanied by a larger 

 amount of oscillation than when the rain-fall is below the 

 average. During the remaining months of the year the 

 converse of this holds good. 



Upon the mean of the year, a rain-fall below the 

 average is accompanied by a less amount of oscillation 

 than when the rain-fall is above the average : this agrees 

 with what has been deduced for Geneva ; but still, during 

 some of the months, it appears as if some disturbing cause 

 existed at the higher elevation which did not exist at the 

 lower. 



The mean readings of the barometer for each month, 

 reduced to 32*^ F., during the period 1848- 1858, were as 

 follows : — 



