﻿HYDROLOGY 
  OF 
  NEW 
  YORK 
  375 
  

  

  is 
  about 
  4000 
  cubic 
  feet 
  per 
  second. 
  They 
  are 
  mostly 
  of 
  modern 
  

   types 
  and 
  have 
  been 
  tested 
  at 
  Holyoke. 
  When 
  the 
  flashboards 
  

   are 
  on, 
  computations 
  at 
  Fort 
  Edward 
  have 
  been 
  made 
  by 
  the 
  

   Francis 
  formula 
  for 
  sharp-crested 
  weir, 
  but 
  when 
  the 
  flashboards 
  

   are 
  off, 
  the 
  flow 
  is 
  computed 
  by 
  means 
  of 
  the 
  East 
  Indian 
  engi- 
  

   neers' 
  formula. 
  

  

  In 
  the 
  winter 
  of 
  1896-97 
  a 
  flood 
  spillway 
  was 
  cut 
  in 
  the 
  rock 
  

   at 
  the 
  south 
  end 
  of 
  the 
  dam 
  over 
  which 
  the 
  water 
  begins 
  to 
  flow 
  

   whenever 
  it 
  reaches 
  the 
  level 
  of 
  the 
  crest 
  of 
  the 
  flashboards. 
  The 
  

   profile 
  of 
  this 
  spillway 
  is 
  irregular 
  and 
  causes 
  a 
  good 
  deal 
  of 
  

   uncertainty 
  in 
  the 
  calculated 
  flows 
  during 
  high 
  water. 
  Indeed, 
  

   the 
  uncertainty 
  is 
  so 
  great 
  that 
  the 
  writer 
  has 
  for 
  a 
  number 
  of 
  

   years 
  been 
  unwilling 
  to 
  publish 
  the 
  record 
  of 
  this 
  dam. 
  He 
  has, 
  

   however, 
  finally 
  reviewed 
  it, 
  recomputing 
  a 
  portion 
  of 
  the 
  same, 
  

   and 
  the 
  figures 
  are 
  given 
  for 
  what 
  they 
  are 
  worth. 
  There 
  is 
  con- 
  

   siderable 
  uncertainty 
  in 
  the 
  high-water 
  flows 
  — 
  perhaps 
  as 
  much 
  

   as 
  25 
  per 
  cent. 
  The 
  entire 
  low-water 
  flow 
  passes 
  through 
  the 
  

   water 
  wheels, 
  and 
  there 
  may 
  be 
  some 
  uncertainty 
  in 
  this, 
  although 
  

   not 
  as 
  great 
  as 
  in 
  the 
  flood 
  flows. 
  

  

  The 
  summer 
  flow 
  of 
  the 
  Hudson 
  river 
  at 
  Meckanicville 
  and 
  Fort 
  

   Edward 
  is 
  materially 
  increased 
  by 
  the 
  outgo 
  from 
  Indian 
  river 
  

   dam, 
  built 
  in 
  1898. 
  A 
  record 
  of 
  the 
  flow 
  at 
  Indian 
  lake 
  has 
  been 
  

   kept 
  since 
  July, 
  1900. 
  

  

  The 
  geology 
  of 
  the 
  Hudson 
  river 
  basin 
  is 
  complicated 
  — 
  from 
  

   its 
  mouth 
  to 
  its 
  extreme 
  headwaters 
  it 
  crosses 
  nearly 
  every 
  

   formation 
  appearing 
  in 
  the 
  State 
  of 
  New 
  York. 
  

  

  Discharge 
  measurements 
  of 
  C 
  rot 
  on 
  river. 
  This 
  stream 
  serves 
  

   as 
  the 
  principal 
  source 
  of 
  water 
  supply 
  for 
  the 
  City 
  of 
  New 
  York, 
  

   Borough 
  of 
  Manhattan. 
  The 
  average 
  daily 
  consumption 
  of 
  water 
  

   in 
  all 
  the 
  Boroughs 
  of 
  the 
  City 
  of 
  New 
  York 
  was, 
  in 
  1899, 
  

   371,778,000 
  gallons, 
  distributed 
  as 
  follows: 
  

  

  Gallons. 
  

  

  Manhattan 
  230,000,000 
  

  

  Bronx 
  21,000,000 
  

  

  Brooklyn 
  102,663,000 
  

  

  Queens 
  12,925,000 
  

  

  Richmond 
  5,190,000 
  

  

  The 
  catchment 
  area 
  of 
  the 
  Croton 
  river 
  lies 
  almost 
  entirely 
  

   in 
  New 
  York, 
  only 
  a 
  small 
  portion 
  being 
  in 
  Connecticut. 
  It 
  

  

  