504 REPORT OF THE COMMISSIONERS OF 



River record covers a period of eight years. The other New Jersey data studied 

 cover periods as follows : Ramapo River, 2 years ; Pequamock River, 3 years ; 

 Musconnetcong River, 2 years; Request River, 2 years; Paulins Kill River, 2.5 

 years ; Raritan River, 4 years ; Delaware River, 4 years ; Great Egg Harbor, 3 years. 



For data derived from other States, Mr. Vermeule cites the following : The 

 Sudbury River in Massachusetts, a 16-year record; Croton River, New York, 14 

 years; Connecticut River, 13 years; the Nashaminy Creek, Pa., 7 years; Perkiomen 

 Creek, Pa., 7 years ; Potomac River, 6 years. In regard to the Sudbury and Croton, 

 I shall cite you directly records covering, for the Sudbury, a period of twenty-one 

 years, from 1875 to 1895, inclusive, and for the Croton, records covering a period of 

 twenty-seven years, from 1870 to 1896, inclusive. 



In addition to the Sudbury, in Massachusetts, I shall also cite you two other 

 Massachusetts records — namely, the Lake Cochituate and Mystic Lake records. The 

 Lake Cochituate watershed is adjacent to the Sudbury, and subject substantially to the 

 same meteorological conditions, while the Mystic Lake watershed is distant from 

 twenty to thirty miles, and somewhat nearer the ocean than the Sudbury and 

 Cochituate areas. The Cochituate record covers the period of thirty-three years, from 

 1863 to 1895, inclusive; while the Mystic Lake record covers a period of eighteen 

 years, from 1S78 to 1S95, inclusive. 



As stated by Mr. Desm.ond FitzGerald, the Sudbury River has a drainage area of 

 75.2 square miles; the Mystic, 26.9 square miles, and the Cochituate 18.9 square 

 miles, the three together forming the present source of Boston's water supply. The 

 Sudbury is hilly, with steep slopes and some large swamps within its borders. The 

 Cochituate, although adjoining the Sudbury, is entirely dissimilar. The slopes are flat 

 and sandy with the surface mostly modified drift, while the Sudbury is mostly com- 

 posed of unmodified drift The Sudbury and Cochituate watersheds are northwest of 

 Boston, while the Mystic lies to the north of Boston about thirty miles distant from the 

 Sudbury and Cochituate. The surface of the Mystic watershed is steeper than 

 the Cochituate, and less steep than the Sudbury. In order to determine whether there 

 is any easily traceable relation between mean temperature, rainfall, run-off and 

 evaporation, I have tabulated the records of not only these three drainage areas but 

 of all other drainage areas considered, in the following manner: The months from 

 December to May, inclusive, are taken as the storage period; June to August, 

 inclusive, make the growing period, while September to November, inclusive, make 

 the replenishing period. In the storage period the temperature is low, and the 

 run-off a very large per cent, of the total rainfall. In the growing period vegetation 

 is active and temperature is high, and the run-off is only a very small per cent, of 

 the total rainfall. In the replenishing period vegetation is inert and the temperature 



