125 



Hydraulic Investigations. 



(Mean •129 = L.1*346-09» = L. 1-254) 



Y. at 60°. 



DlHlAT. 



1388? 

 452100 



747 

 1063 



(Mean -017 = L.1 -041 -009 = L. 1-022 



Tt appears from thi> comparison, that in the forty experi- 

 ments extracted from the collection, which served as a basis 

 lor Dubuat's calculations, the mean error of his formula is 

 ^ T of the whole velocity, and that of mine ^j- only ; but if 

 we omit the four experiments, in which the superficial ve- 

 locity only of a river was observed, and in which I have 

 calculated the mean velocity by Dubuat's rules, the mean 

 error of the remaining 36 is --$-, according to my mode of 

 calculation, and -J T according to Mr. Dubuat's ,• so that, on 

 the whole, the accuracy of the two formulae may be con- 

 sidered as precisely ecjual with respect to these experiments. 

 In the six experiments which Dubuat has wholly rejected, 



the 



