﻿HYDROLOGY 
  OP 
  NEW 
  YORK 
  107 
  

  

  the 
  nations 
  of 
  the 
  earth 
  being 
  fortunately 
  agreed 
  upon 
  their 
  

   measures 
  of 
  time, 
  have 
  settled 
  upon 
  one 
  second 
  of 
  time 
  as 
  the 
  

   unit 
  to 
  use 
  in 
  measuring 
  water. 
  Nevertheless, 
  the 
  million 
  United 
  

   States 
  gallons 
  in 
  twenty-four 
  hours 
  has 
  become 
  a 
  standard 
  for 
  

   city 
  water 
  supply 
  practice 
  in 
  the 
  United 
  States, 
  and 
  an 
  acre 
  in 
  

   area 
  covered 
  an 
  inch 
  or 
  a 
  foot 
  deep 
  in 
  a 
  month 
  or 
  in 
  a 
  year 
  is 
  

   used 
  in 
  irrigation 
  practice. 
  But 
  I 
  would 
  warn 
  all 
  engineers 
  to 
  

   be 
  very 
  slow 
  to 
  add 
  to 
  the 
  number 
  of 
  such 
  standards 
  of 
  measure 
  

   for 
  flowing 
  water, 
  and 
  to 
  abstain 
  from 
  and 
  frown 
  down 
  such 
  

   absurd 
  standards 
  as 
  cubic 
  yards 
  per 
  day, 
  or 
  tons 
  weight 
  of 
  water 
  

   per 
  day, 
  or 
  even 
  cubic 
  feet 
  per 
  minute 
  (instead 
  of 
  second), 
  and 
  

   other 
  incongruities. 
  . 
  . 
  As 
  exercises 
  in 
  the 
  art 
  of 
  arithmetic 
  

   for 
  children 
  such 
  computations 
  may 
  have 
  value, 
  but 
  in 
  the 
  work 
  

   of 
  civil 
  engineers 
  they 
  become 
  a 
  stumbling 
  block 
  to 
  an 
  advance 
  

   of 
  knowledge, 
  and 
  while 
  unduly 
  magnifying 
  the 
  unessentials, 
  they 
  

   indicate 
  a 
  deplorable 
  lack 
  of 
  appreciation 
  of 
  the 
  essentials 
  of 
  the 
  

   art 
  of 
  the 
  civil 
  engineer. 
  

  

  Cubic 
  measures 
  do 
  well 
  enough 
  for 
  the 
  contents 
  of 
  vessels, 
  or 
  

   as 
  we 
  may 
  express 
  it, 
  for 
  dealing 
  with 
  the 
  science 
  of 
  hydrostatics. 
  

   But 
  so 
  soon 
  as 
  the 
  water 
  to 
  be 
  measured 
  is 
  in 
  motion, 
  or 
  so 
  soon 
  

   as 
  the 
  science 
  of 
  hydraulics 
  has 
  been 
  entered 
  upon, 
  we 
  must 
  get 
  

   clearly 
  in 
  our 
  minds 
  the 
  idea 
  of 
  rates 
  of 
  flow, 
  or 
  of 
  a 
  procession 
  

   of 
  such 
  cubic 
  volumes 
  passing 
  a 
  given 
  point 
  in 
  a 
  certain 
  unit 
  of 
  

   time, 
  as 
  of 
  a 
  flow 
  of 
  so 
  many 
  cubic 
  feet 
  per 
  second. 
  

  

  Very 
  little 
  can 
  be 
  added 
  to 
  what 
  Mr 
  Herschel 
  has 
  here 
  said. 
  

   It 
  is 
  a 
  clear 
  exposition 
  of 
  the 
  whole 
  subject. 
  Such 
  units 
  as 
  cubic 
  

   feet 
  per 
  day 
  and 
  cubic 
  miles 
  have 
  clearly 
  no 
  place 
  in 
  a 
  modern 
  

   paper 
  on 
  hydrology. 
  

  

  The 
  unit 
  of 
  inches 
  on 
  the 
  catchment 
  area 
  may, 
  however, 
  be 
  

   pointed 
  out 
  as 
  an 
  exception 
  to 
  the 
  foregoing 
  general 
  rule. 
  This 
  

   unit 
  is 
  exceedingly 
  convenient 
  because 
  it 
  admits 
  of 
  expressing 
  

   rainfall 
  and 
  runoff 
  in 
  the 
  same 
  unit 
  and 
  without 
  reference 
  to 
  the 
  

   area. 
  It 
  brings 
  out 
  a 
  number 
  of 
  relations 
  not 
  otherwise 
  easily 
  

   shown, 
  as 
  will 
  be 
  exhibited 
  in 
  discussing 
  the 
  tables 
  accompanying 
  

   this 
  report. 
  

  

  Characteristics 
  of 
  the 
  minimum 
  runoff. 
  Since 
  the 
  rainfall 
  varies 
  

   so 
  widely, 
  the 
  runoff, 
  which 
  is 
  a 
  function 
  of 
  the 
  rainfall, 
  will 
  also 
  

   vary 
  widely. 
  On 
  the 
  Hudson 
  river 
  the 
  maximum 
  runoff 
  of 
  33.08 
  

   inches, 
  with 
  a 
  rainfall 
  of 
  53.87 
  inches, 
  occurred 
  in 
  1892. 
  The 
  

   minimum, 
  with 
  a 
  runoff 
  of 
  17.46 
  inches 
  and 
  a 
  rainfall 
  of 
  36.37 
  

   inches, 
  occurred 
  in 
  1895. 
  On 
  the 
  Genesee 
  river 
  the 
  observed 
  maxi- 
  

  

  