﻿116 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

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

   determined 
  by 
  gagings. 
  

  

  1= 
  constant 
  = 
  /_^00><12\ 
  

   \640x43560/' 
  

  

  C^constant^/ 
  8 
  ^ 
  QQ 
  X 
  12X305 
  > 
  | 
  

   \ 
  640x43560 
  /■ 
  

  

  C 
  3 
  = 
  constant 
  = 
  ( 
  I 
  

  

  \7.48x640x435t>0/' 
  

  

  C 
  4 
  = 
  constant 
  =(— 
  

  

  The 
  constants, 
  C 
  1? 
  C 
  2 
  , 
  C 
  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 
  versa. 
  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=eatchment 
  area 
  in 
  square 
  miles. 
  

  

  rj 
  9. 
  (12) 
  

  

  a 
  ~ 
  20.81) 
  A 
  v 
  ; 
  

  

  and 
  Q 
  = 
  26.89 
  Ax 
  d. 
  (13) 
  

  

  This 
  formula 
  is 
  convenient 
  for 
  use 
  in 
  considering 
  floods. 
  1 
  

  

  Maximum 
  discharge 
  formulas. 
  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 
  the 
  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 
  ^M 
  3 
  ; 
  and 
  (14) 
  

  

  Ryves's 
  formula, 
  D 
  = 
  C 
  /W. 
  (15) 
  

  

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

   Government), 
  1890. 
  

  

  