LIV. DISCUSSION. 



tion can be recovered by means of boring, so bringing it to 

 the surface again, if the physical features of the district lend 

 themselves to such treatment. Whilst it is most important, 

 under the former heads, to know the maximum rainfall, under 

 this head the mean and minimum rainfall, the latter both in 

 amount and duration, should be ascertained. The maximum 

 period, during which the demand for water exceeds the natural 

 yield, determines the amount of storage required. 



To properly deal with this branch of the paper in a thorough 

 manner would occupy too much time. These few remarks will, 

 however, sufficiently indicate how far its treatment differs from 

 the other branches of the subject. 



Discussion. 



(Brief Abstract). 

 Mr. C. O. Burge said that as his name had been mentioned 

 as the author of one of the formulae quoted, he wished to say a 

 few words about it, more especially as it had been included in a 

 standard work — Jackson's " Hydraulic Manual " — as one of the 

 three best-known formulae in connection with flood discharge. He 

 had been enabled, when in charge of about 100 miles of open line 

 railway maintenance in India, to measure the maximum flood 

 discharge for many years of a great number of large openings ; 

 and from this, and the data of the several basins, he had put 

 together the formula in question. This, after publication in an 

 article in the " Professional Papers on Indian Engineering, ,, had 

 been quoted in the Manual, with a criticism with which he 

 was disposed to agree, and from there had got into Moles- 

 worth's Pocket-Book. That was nearly 30 years ago, but his 

 experience since led him to distrust all formulae on this subject. 

 In all of them the constant had too much to bear. For instance, 

 in the formula in question the constant had to include maximum 

 rainfall in a given time, concentration of rainfall, percolation, 

 evaporation, dissimilarity of tributaries from main stream, the 

 influence of ponds or waterholes, <fcc, all of which varied so 



