THE MEASUREMENT OF EAm. 



^ 



By uniting the Swineshaw observations with those in 

 Longdendale, the mean rain and flow would be as follows :— 



1847. 



January ... 

 February.. 



March 



April 



May 



June 



July 



August 



September 

 October... 

 November. 

 December . 



Raik. 



111. Dec. 

 2 36 



30 



70 

 22 

 48 

 40 

 62 

 32 

 38 

 66 

 48 

 74 



53 56 



Flow. 



In. Dec. 



85 

 10 

 30 

 12 



75 

 65 



99 



24 

 12 



67 

 25 



8 55 



46 59 



On examining the last Tables, it will be found that in 

 many months, particularly during October, November, and 

 December, the quantity of water flowing off the ground 

 appears to be larger than the rain which fell during the 

 same period. 



During months in which little rain fell, this would be ac- 

 counted for by the produce of the springs ; but in periods of 

 excessive rain, such as the last four months of 1847, in which 

 the rain was 24^ inches, and that which flowed off the 

 ground 25^ inches, although it is reasonable to suppose that 

 the ground would be so saturated that very nearly all the 

 rain would flow down the streams in torrents, yet we could 

 scarcely calculate upon more. The produce of springs from 

 water previously stored up would no doubt add something 

 to the quantity, but not enough to account for the whole. 



It is most likely, therefore, that either the streams have 

 been over-estimated, or the rain under-measured. 



On a careful examination of all the returns from which the 

 tables have been constructed, it seems probable that the 

 latter supposition is the correct one. Every stream bears the 



