190 



NEW YORK STATE MUSEUM 



is further mostly limited to streams with considerable length of 

 record. 



Description of Muskingum , Genesee, Croton and Hudson rivers. 

 Table 42 gives the rainfall, runoff, and evaporation of the storage, 

 growing and replenishing periods, as well as the total of these 

 three items, on the Muskingum river, for the years 18SS-1S95, 

 inclusive. The minimum year was 1895, the total runoff being 

 4.90 inches. The maximum occurred in 1890, with a total runoff 

 of 26.84 inches. The mean runoff for the entire period is 13.1 

 inches. 



Table 43 gives the same facts for the Genesee river for the years 

 1890-1898, inclusive. In this table, for the years 1890-1892, the 

 record of Oatka creek which was gaged by the writer, has been 

 used. For a portion of 1893 the results are computed. The dam 

 at Mount Morris, at which gagings were taken, was carried away 

 by a flood early in 1897, and for the years 1897 and 1898 the 

 gaging record has been deduced by comparison of the rainfalls 

 with those at Rochester, where gagings are kept by the City Engi- 

 neer. The results, aside from those for the years 1894-1896, must 

 be considered somewhat approximate, although probably within 

 10 per cent of the truth. The mean evaporation for the years 

 1S94-1S96 was 27.21 inches. 



Tables 66 and 67 exhibit the rainfall, runoff, and evaporation of 

 the storage, growing, and replenishing periods for Croton river, 

 from 1S68-1899, inclusive, a period of thirty-two years. This record 

 has been revised as per experiments at Cornell University, described 

 by John R. Freeman, member American Society Civil Engineers, in 

 his report to the Comptroller in 1900. As shown by Mr Freeman, 

 the rainfall record from 1868-1876, inclusive, is not very reliable, 

 and accordingly two sets of means are given. The mean rainfall 

 from 1868-1876, inclusive, was 45 inches, the mean runoff 23.37 

 inches, and the mean evaporation 21.63 inches. For the second 

 period the rainfall from 1877-1S99, inclusive, has been so ration- 

 ally treated by Mr Freeman as to leave nothing to be desired. The 

 means for this second period are: rainfall, 49.33 inches; runoff, 

 22.81 inches, and evaporation, 26.52 inches. A comparison of 

 these two sets of means shows how dangerous it is to draw final 



