lllj 



NEW YORK STATE MUSEUM 



Q=cubic feet per second flowing from the catchment area, as 

 determined by gaarings. 



C,= constant = / 86400 X 12 ) 

 ^640x43560/' 



C<= constant = /?6400><12x^\ 

 V 640x43560 /• 



C 3 — constant = / ±? ^ 



V7.48X 640x43560/' 



C,= constant = 



\640y ' 



The constants, C 1? C 2 , 3 , and C 4 , are left in form for log- 

 arithmic computation. For a given case, catchment area is con- 

 stant, and A, in the final logarithmic form, will be combined 

 with these. 



It is sometimes convenient to have a formula for converting 

 discharge in cubic feet per second into inches draining from an 

 area in 24 hours and vice rasa. The following formulas answer 

 to these conditions. In these formulas, 



Q=discharge in cubic feet per second. 



d=discharge over catchment, in depths in inches in 24 hours. 

 A=catchment area in square miles. 



and Q = 26.89 Axd. (13) 

 This formula is convenient for use in considering Hoods. 1 

 Maximum discharge formula*. A considerable number of such 

 have been worked out, but the authors have taken into account 

 so few of the controlling conditions, that they are, at the best, 

 mostly only crude guides, and Hie writer long ago gave up their 

 use, except in cases where only the roughest approximation was 

 required. Two exceptions may. however, from the peculiar form 

 of the coefficient, be briefly noted, viz: 



Dickens's formula, D = C *<5P; and (14) 

 Ry ves's formula, D = C /Ml (15) 



i Irrigation Manual, by Lieut. Gen. J. Mulllns (published for .Madras 

 Government), 1890. 



