RAIN ON THE ALPS. 239 



cially on the side of Italy, where the greatest 

 quantity may be expected from the west winds. 



How far a ridge of hills extends its influence 

 over a plain in regard to the weight of water 

 precipitated, it is not easy to form a decided 

 opinion. It can scarcely be doubted, that the 

 greatest influence will be confined to two or 

 three miles from the ridge ; but some influence 

 may be found in all probability at the distance 

 of ten or even twenty miles or more, according 

 to the greater or less elevation of the moimtains. 



It is matter of curious observation, that the 

 falls at St. Bernard for the four first months of 

 the year, are all greater than for any other 

 months; and that the falls for the next four 

 months, are all less than for any other, thus 

 leaving the four last months to yield about the 

 average monthly quantity. A series of twelve 

 years can scarcely leave a doubt as to the 

 general accuracy of the fact. Possibly there 

 may be some uncertainty as to quantity in 

 regard to the snow; the observers estimate 

 one foot in depth of snow to be equal to one 

 inch in depth of rain ; and the weight of the 

 falls for six or eight months in the year, is snow. 



