﻿HYDROLOGY 
  OP 
  NEW 
  YORK 
  829 
  

  

  found 
  ill 
  1824, 
  on 
  the 
  same 
  reach 
  of 
  canal 
  as 
  was 
  measured 
  by 
  

   Mr 
  Childs 
  in 
  1841, 
  a 
  total 
  loss 
  of 
  from 
  1.68 
  to 
  1.75 
  cubic 
  feet 
  per 
  

   second 
  per 
  mile. 
  It 
  may 
  be 
  assumed 
  that 
  the 
  springs 
  and 
  

   streams 
  allowed 
  for 
  by 
  Mr 
  Childs 
  were 
  delivering 
  into 
  the 
  canal 
  

   in 
  1824 
  the 
  same 
  as 
  in 
  1841, 
  at 
  least 
  0.17 
  to 
  0.25 
  cubic 
  foot 
  per 
  

   second 
  per 
  mile. 
  We 
  have, 
  then, 
  as 
  the 
  total 
  supply 
  in 
  1824 
  

   from 
  1.92 
  to 
  2.00 
  cubic 
  feet 
  per 
  second 
  per 
  mile. 
  Adopting 
  the 
  

   latter 
  figure 
  as 
  a 
  maximum 
  to 
  compare 
  with 
  Mr 
  Childs's 
  figure 
  

   of 
  1.42 
  cubic 
  feet 
  per 
  second 
  per 
  mile, 
  as 
  found 
  in 
  1841, 
  the 
  con- 
  

   clusion 
  is 
  reached 
  that 
  the 
  decrease 
  in 
  the 
  loss 
  by 
  filtration 
  — 
  due 
  

   presumably 
  to 
  the 
  gradual 
  silting 
  up 
  of 
  the 
  bottom 
  — 
  is 
  some- 
  

   thing 
  like 
  0.58 
  cubic 
  foot 
  per 
  second 
  per 
  mile. 
  

  

  This 
  conclusion 
  could 
  be 
  applied 
  to 
  the 
  conditions 
  of 
  the 
  Erie 
  

   canal 
  improvement 
  of 
  1895 
  in 
  which 
  it 
  was 
  proposed 
  to 
  excavate 
  

   one 
  foot 
  from 
  the 
  bottom 
  of 
  many 
  of 
  the 
  levels. 
  The 
  effect 
  of 
  this 
  

   would 
  be 
  to 
  remove 
  the 
  silt 
  accumulations 
  of 
  many 
  years, 
  thus 
  

   placing 
  the 
  bottom 
  of 
  the 
  canal, 
  as 
  regards 
  porousness 
  and 
  conse- 
  

   quent 
  percolation 
  and 
  filtration 
  loss, 
  in 
  the 
  same 
  condition 
  as 
  

   when 
  first 
  constructed. 
  This 
  consideration 
  alone 
  indicated 
  the 
  

   necessity 
  of 
  making 
  the 
  water 
  supply 
  of 
  the 
  enlarged 
  canal 
  

   liberal 
  in 
  order 
  to 
  answer 
  the 
  demands 
  of 
  the 
  first 
  few 
  years 
  

   while 
  the 
  bottom 
  was 
  again 
  attaining 
  a 
  fixed 
  condition. 
  

  

  The 
  experience 
  of 
  over 
  eighty 
  years 
  in 
  the 
  operation 
  of 
  the 
  

   Xew 
  York 
  State 
  canals 
  has 
  thoroughly 
  shown 
  the 
  futility 
  of 
  any 
  

   attempt 
  at 
  excessive 
  economy 
  in 
  water 
  supply. 
  In 
  the 
  absence 
  

   of 
  systematic 
  information 
  as 
  to 
  yield 
  of 
  streams, 
  the 
  general 
  

   tendency 
  has 
  been 
  to 
  overrate 
  the 
  summer 
  flow, 
  with 
  the 
  result 
  of 
  

   shortage 
  frequently 
  at 
  points 
  where 
  the 
  supply 
  was 
  believed 
  to 
  be 
  

   ample. 
  The 
  chief 
  sources 
  of 
  such 
  shortage 
  may 
  be 
  enumerated 
  

   as 
  follows 
  : 
  

  

  1) 
  The 
  great 
  variation 
  in 
  the 
  yield 
  of 
  catchment 
  areas 
  from 
  

   year 
  to 
  year, 
  by 
  reason 
  of 
  differences 
  in 
  the 
  rainfall, 
  humidity, 
  

   and 
  temperature. 
  

  

  2) 
  The 
  cutting 
  off 
  of 
  forests, 
  which 
  has 
  increased 
  somewhat 
  

   the 
  spring-flood 
  flows 
  and 
  decreased 
  the 
  summer 
  flow. 
  

  

  3) 
  The 
  systematic 
  drainage 
  of 
  large 
  areas, 
  which 
  has 
  also 
  

   tended 
  to 
  increase 
  the 
  flood 
  flows 
  and 
  decrease 
  the 
  summer 
  flows. 
  

  

  