THU MEASUBEMENT OF EAIIf. 21 



In the preceding table, the last column, which is the mean 

 of all the rain observations, omitting Bruslies on account of 

 its being in another valley, may be taken as the mean fall 

 of rain for the year 1847 in the Longdendale district, so 

 fer at least as the gauges may be supposed to indicate the 

 real quantity. 



The measurements of the streams, hovrever, lead to the 

 belief that more rain has fallen than the rain gauges show. 

 They are placed in the valleys, and at mean heights, none 

 being quite on the tops of the hills; and it is probable that 

 there heavy rain has fallen, and contributed to swell the 

 streams, which has been beyond the range of the rain gauges. 



The next table exhibits the depth of water flowing off 

 tl)e ground, as measured in various streams in the Longden- 

 dale valley. It shows also the drainage or collecting ground 

 to the point of measurement on each stream, and the mean^^ 

 flow as deduced from all the observations. 



