﻿HYDROLOGY 
  OF 
  NEW 
  YORK 
  125 
  

  

  Cochituate 
  and 
  Mystic 
  rivers 
  have 
  been 
  deduced, 
  it 
  is 
  believed, 
  by 
  

   Mr 
  Francis's 
  formula 
  for 
  the 
  Merriniac 
  dam. 
  As 
  to 
  the 
  Desplaines 
  

   river, 
  a 
  discharge 
  curve 
  determined 
  by 
  current 
  meter 
  has, 
  it 
  is 
  

   believed, 
  been 
  applied. 
  1 
  The 
  English 
  streams 
  cited, 
  Lea, 
  Wandle, 
  

   Thames, 
  etc. 
  have 
  probably 
  been 
  gaged 
  by 
  a 
  sharp-crested 
  weir, 
  

   and 
  the 
  others 
  mostly 
  by 
  the 
  current 
  meter 
  and 
  a 
  rating 
  table. 
  

  

  Russell's 
  formulas. 
  Mr 
  Thomas 
  Eussell 
  2 
  gives 
  the 
  following 
  

   formulas 
  for 
  the 
  runoff 
  of 
  the 
  Ohio, 
  Upper 
  Mississippi, 
  and 
  Upper 
  

   and 
  Middle 
  Missouri 
  valleys, 
  in 
  terms 
  of 
  the 
  annual 
  rainfall. 
  For 
  

   the 
  Ohio 
  river 
  the 
  formula 
  is 
  as 
  follows: 
  

  

  0=0.600+0.95 
  R— 
  0.90 
  R 
  (0.975 
  e— 
  0.421 
  e 
  2 
  +0.626 
  e 
  3 
  ). 
  (27) 
  

   For 
  the 
  Upper 
  Mississippi 
  it 
  is 
  : 
  

  

  0=0.50+0.93 
  R— 
  0.88 
  R 
  (1.131 
  e— 
  0.383 
  e 
  2 
  ). 
  (28) 
  

  

  For 
  the 
  Upper 
  and 
  Middle 
  Missouri 
  it 
  is 
  : 
  

  

  0=0.12+0.98 
  R— 
  0.93 
  R 
  (0.91 
  e— 
  0.220 
  e 
  2 
  +0.009 
  e 
  3 
  ). 
  (29) 
  

  

  In 
  these 
  formulas 
  R 
  is 
  the 
  rainfall 
  for 
  the 
  month 
  in 
  cubic 
  miles 
  ; 
  

   e 
  is 
  the 
  quantity 
  of 
  water 
  required 
  to 
  saturate 
  the 
  air 
  at 
  any 
  time, 
  

   equal 
  to 
  the 
  difference 
  between 
  what 
  the 
  air 
  contains 
  and 
  the 
  

   amount 
  if 
  it 
  was 
  saturated 
  ; 
  and 
  O 
  is 
  the 
  < 
  utflow 
  or 
  runoff. 
  

  

  These 
  formulas 
  are 
  interesting 
  in 
  the 
  present 
  connection, 
  

   because 
  they 
  recognize 
  the 
  fact 
  that 
  every 
  stream 
  must 
  have 
  its 
  

   own 
  formula. 
  The 
  variation 
  in 
  runoff 
  on 
  the 
  Ohio, 
  Mississippi 
  

   and 
  Missouri 
  rivers 
  will 
  be 
  observed 
  on 
  inspection 
  of 
  the 
  formulas. 
  

   Like 
  all 
  formulas 
  of 
  this 
  class 
  they 
  are 
  subject 
  to 
  considerable 
  

   variation. 
  In 
  the 
  month 
  of 
  October, 
  1881, 
  the 
  computed 
  outflow 
  

   of 
  the 
  Missouri 
  river 
  was 
  4.9 
  culbic 
  miles 
  and 
  the 
  observed 
  flow 
  

   was 
  1.6 
  cubic 
  miles, 
  a 
  difference 
  of 
  3.3 
  cubic 
  miles. 
  

  

  Relation 
  "between 
  catchment 
  area 
  and 
  maximum, 
  minimum 
  and 
  

   mean 
  runoff. 
  It 
  is 
  quite 
  common 
  for 
  hydrologists 
  to 
  assume 
  that 
  

   there 
  is 
  a 
  relation 
  between 
  catchment 
  area 
  and 
  maximum, 
  mini- 
  

   mum 
  and 
  mean 
  runoff, 
  the 
  general 
  proposition 
  being 
  that 
  mean 
  

  

  1 
  Data 
  Pertaining 
  to 
  Rainfall 
  and 
  Stream 
  Flow, 
  by 
  Thomas 
  T. 
  Johnston: 
  

   Jour. 
  Western 
  Soc. 
  Engrs., 
  Vol. 
  I, 
  No. 
  3, 
  June, 
  1896. 
  

  

  2 
  Rainfall 
  and 
  River 
  Outflow 
  in 
  the 
  Mississippi 
  Valley, 
  by 
  Thomas 
  Rus- 
  

   sell: 
  Ann. 
  Rept. 
  Chief 
  Signal 
  Officer 
  for 
  the 
  year 
  1889, 
  Part 
  I, 
  Appendix 
  14. 
  

  

  