New York State 



41 



15 years have been used in computing the averages. Several 

 of the records cover a period of more than 90 years, a few more 

 than 50 years, and many more than 30 years. Several 

 types of rain gauges have been used in the series, but it is believed 

 that no serious errors have arisen therefrom. 



Precipitation occurring in the form of snow was reduced to its 

 water equivalent by melting the snow and measuring and record- 

 ing the depth of the water thus obtained, as in the case of rain ; or, 

 when it was impracticable to melt the snow, the water equivalent 

 was recorded as one tenth of the actual depth of the unmelted 

 snowfall. When snow is very wet or very dry the error in apply- 

 ing this so-called " 1 to 10 rule " is considerable, but when applied 

 to the snowfall of a season, which includes snowfalls of every char- 

 acter, or to that of many seasons, experience has shown that the 

 error, so far as averages are concerned, is not serious. 



Le3S than 30. 30 to 35. 35 to 40 40 to 45 More than 45. 



Fig. 13. — Normal Annual Precipitation 



