162 



There is no probability that the mean yearly rainfall will be less 

 than 30 inches for the next fifty-seveu years. The mean rainfall 

 from 1836-92 inclusive is #44.05 inches, and twenty-five of the 

 years during this period had a mean rainfall of 44 or more inches, 

 while thirty-two years had a mean below 44 inches. Therefore 

 the probability that the mean yearly precipitation for the next 

 period of fifty-seven years will be equal to the mean of the last 

 fifty-seven years, is as 25 : 32. 



Snovjfall. 

 It is found that the mean snowfall varies greatly from year to 

 year. During the last fifty-two years the annual depth has ranged 

 from 17 to 87 inches. The whole amount recorded is 230.42 feet, 

 or an average of 53.17 inches per year. The curve shows that 

 very seldom does the same depth occur twice during this period. 

 Twenty-seven times the yearly mean was 52 or more inches, and 

 twenty-five times below 52. That is, the probability that at least 

 52 inches of snow may fall each of the next fifty-two years is as 

 27 : 25. If the time be divided into three periods, beginning with 

 1840, it is found that the first seventeen years 923.7 inches of 

 snow, or an average of 54.33 inches per year, was recorded ; the 

 second period of seventeen years, 951.5 inches, or an average of 

 55.9 inches each year ; while the last eighteen years the whole 

 amount is 889.9 inches, or a yearly mean of 49.44 inches. This 

 would seem that for the last eighteen years the mean yearly, 

 snowfall had gradually decreased. 



