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NEW YORK STATE MUSEUM 



an average runoff over a large district of country, including the 

 usual varieties of soil, while Madison brook would probably not 

 differ materially from the general average in this State. 



In his documentary history of the Xew York State canals, 1 

 S. H. Sweet analyzes Mr Jervis's measurements of discharge of 

 Eaton and Madison brooks and points out several probable errors, 

 specially in the Madison brook result, where because the measure- 

 ments indicate only what was actually discharged through the 

 sluice pipes each day instead of what drained off from the valley, 

 he concludes that the real drainage of the Madison brook area in 

 1835 was about 0.518 of the rainfall, instead of 0.449, as given 

 by Mr Jervis. Inasmuch as the Eaton brook and Madison brook 

 measurements have only historical interest at the present time, 

 this branch of the subject is not here pursued at length. So far 

 as can be learned the measurements of these two streams by 

 Mr Jervis were the first systematic measurement of the runoff of 

 streams in the United States. 



Geologically Eaton and Madison brooks lie in the horizon of 

 the Hamilton shales. 



MAXIMUM AND MINIMUM FLOW OF STREAMS 



The maximum flow of a stream is merely another name for 

 flood-flow, and since floods are very destructive in Xew York the 

 general causes may be briefly considered. 



A typical Xew York stream rises in the hills and mountainous 

 country at the sides of the valleys and flows down, with declivities 

 steepest at the headwaters and in its lateral tributaries, the main 

 stream growing flatter toward its mouth. The profile of nearly 

 all New York streams is therefore roughly concave in form. 



Streams having a concave profile are ordinarily divided into 

 three portions, as follows : 



1) The upper or torrential portion, where erosion is active and 

 in excess of deposition. 



2) The normal portion, where erosion and deposition are about 

 equal and the stream is neither lowering nor raising its bed. 



3) The alluvial portion, where deposition exceeds erosion and 

 the bed is gradually being raised, and where also this raising of 



'Ann. rept state Engineer and Surveyor for 1862; 



