KI SI IKK IKS, (;.\MK .\M> KORESTS. 521 



grass, 15.4 inches ; fallow land, peas, beans, orchards, and niiscellaneons, 12 inches; 

 clover, 12.9 inches; and forest, 3 6 inches. Proceedint,' on this line it was ascertained 

 that in 1850, the total depth of water over the entire area of Wyoming County, 

 required to fully support vegetation as it existed in that year, amounted to 10.17 

 inches; in 1850 it amounted to 11.15 inches; in 1870, to 11.89 inches; in 1880, to 

 13.24 inches; and in 1890, to 13-57 inches. Hence the conclusion seemed to be 

 safely drawn that in 1890, due to changes in forest area and to quality of crops grown, 

 the amount of water required in Wyoming County to support vegetation during the 

 growing season would amount to 3.4 inches more than in 1850. Why a mill stream 

 in Wyoming County, which was ample for all demands in 1850, entirely failed in 1890, 

 seemed, therefore, fully explained. 



In order to determine whether such conclusion was in accord with the rainfall 

 records of Western New York a large number of such were tabulated in periods in the 

 manner already described, with December to May, inclusive, making the storage 

 period: June to August, inclusive, the growing period; and September to November, 

 inclusive, the replenishing period. From a tabulation of the rainfall records kept at 

 Middlebury Academy, in Wyoming County, for certain years — seventeen in all — from 

 1826 to 1848, inclusive, the mean rainfall for the growing period was determined at 

 9.52 inches. In 1832 it was only 6.76 inches. The maximum at Middlebury 

 Academy was 14.36 inches in the growing ])eriod of 1828. Tabulating more recent 

 records it was found that at Arcade, in Wyoming County, from 1891 to 1896, the 

 mean of the growing period was 13.61 inches; the minimum of 9.62 inches occurring 

 in 1S94. At Le Roy, in the adjoining County of Genesee, the mean of the growing 

 period from 1891 to 1895, inclusive, was 10.31 inches; the minimum being 6.61 inches 

 in 1894. At Rochester the records show a mean of the growing period for the years 

 from 187 1 to 1896, inclusive, of 8.29 inches; the minimum of the growing period 

 being only 5.0 inches in 1887. It appeared, therefore, that at the jjresent time, with 

 the drainage areas almost entirely deforested, streams must necessarily be very low 

 during the summer season of nearly every year. Practical observation in Western 

 New York amply confirms this theoretical deduction. 



The foregoing data as to summer rainfall show why it is that even fully forested 

 areas are sometimes subject to drought. When the growing period rainfall sinks to 

 5.0 or 6.9 inches, even a forested area will be dry. The difference is that in a large 

 forest area summer droughts occur only occasionally, while in Western New York, 

 under present conditions of forestation, they occur about every other year. Failure to 

 appreciate just this difTerence has frequently misled investigators. 



