﻿HYDROLOGY 
  OF 
  NEW 
  YORK 
  373 
  

  

  in 
  which 
  — 
  

  

  B 
  =3 
  the 
  width 
  of 
  the 
  crest 
  in 
  linear 
  feet 
  ; 
  

  

  C 
  = 
  the 
  coefficient 
  for 
  a 
  thin-edged 
  weir, 
  corresponding 
  to 
  a 
  

  

  depth 
  d, 
  as 
  per 
  equation 
  (39), 
  and 
  

   C 
  = 
  the 
  adjusted 
  coefficient 
  corresponding 
  to 
  a 
  given 
  breadth 
  

   B 
  and 
  a 
  depth 
  d. 
  1 
  

  

  In 
  the 
  case 
  of 
  the 
  Mechanicville 
  dam 
  we 
  have 
  a 
  stone 
  crest 
  7 
  

   feet 
  in 
  width 
  and 
  slightly 
  inclined 
  upstream. 
  The 
  width 
  of 
  the 
  

   river 
  a 
  short 
  distance 
  above 
  the 
  dam 
  is 
  considerably 
  over 
  800 
  feet 
  ; 
  

   the 
  depth 
  for 
  some 
  distance 
  back 
  is 
  from 
  16 
  to 
  20 
  feet. 
  In 
  order 
  

   to 
  avoid 
  a 
  correction 
  for 
  velocity 
  of 
  approach, 
  a 
  crest 
  was 
  assumed 
  

   5 
  feet 
  wide 
  and 
  values 
  of 
  C 
  were 
  computed 
  on 
  that 
  basis. 
  

  

  Having 
  obtained 
  values 
  of 
  C 
  for 
  d 
  = 
  0.25, 
  0.50, 
  0.75, 
  1.00, 
  1.25, 
  

   1.50, 
  1.75 
  feet, 
  and 
  so 
  on 
  up 
  to 
  8 
  feet, 
  corresponding 
  values 
  of 
  Q 
  

   were 
  computed 
  and 
  plotted 
  at 
  a 
  large 
  scale 
  as 
  a 
  curve 
  with 
  values 
  

   of 
  d 
  as 
  abscissas 
  and 
  the 
  corresponding 
  flows 
  as 
  ordinates. 
  From 
  

   this 
  curve 
  intermediate 
  values 
  of 
  Q 
  have 
  been 
  read 
  off. 
  

  

  The 
  water 
  wheels 
  at 
  Mechanicville 
  have 
  a 
  capacity 
  when 
  they 
  

   are 
  all 
  running 
  of 
  about 
  2400 
  cubic 
  feet 
  per 
  second. 
  The 
  working 
  

   head 
  varies 
  from 
  15 
  to 
  17 
  feet, 
  depending 
  upon 
  the 
  condition 
  of 
  

   the 
  flashboards. 
  A 
  test 
  of 
  a 
  39-inch 
  Hercules 
  wheel, 
  which 
  has 
  

   been 
  in 
  use 
  about 
  eight 
  years, 
  shows 
  the 
  actual 
  discharge 
  to 
  be 
  

   substantially 
  as 
  given 
  in 
  the 
  manufacturers' 
  tables 
  when 
  running 
  

   at 
  the 
  speed 
  of 
  greatest 
  efficiency. 
  

  

  The 
  crest 
  gage 
  is 
  read 
  twice 
  a 
  day 
  and 
  a 
  mean 
  taken 
  for 
  the 
  

   hight. 
  A 
  continuous 
  record 
  is 
  also 
  kept 
  of 
  the 
  run 
  of 
  the 
  water 
  

   wheels 
  at 
  the 
  mill. 
  

  

  Discharge 
  measurements 
  of 
  Hudson 
  river 
  at 
  Fort 
  Edward. 
  

   This 
  station 
  is 
  located 
  at 
  the 
  dam 
  of 
  the 
  International 
  Paper 
  

   Company, 
  which 
  was 
  established 
  by 
  the 
  writer 
  in 
  1895 
  in 
  connec- 
  

   tion 
  with 
  the 
  upper 
  Hudson 
  storage 
  surveys. 
  The 
  dam 
  is 
  of 
  

   timber 
  on 
  rock 
  foundation 
  and 
  with 
  very 
  little 
  leakage. 
  The 
  

   crest 
  is 
  nearly 
  level, 
  587.6 
  feet 
  in 
  length. 
  Flashboards 
  are 
  main- 
  

   tained 
  on 
  the 
  dam 
  15 
  to 
  18 
  inches 
  in 
  hight. 
  

  

  There 
  are 
  sixty-two 
  water 
  wheels 
  in 
  the 
  adjoining 
  mill. 
  A 
  

   record 
  is 
  kept 
  of 
  the 
  daily 
  run 
  of 
  each 
  in 
  hours, 
  as 
  well 
  as 
  the 
  

   workiug 
  head, 
  which 
  is 
  about 
  19 
  feet. 
  The 
  capacity 
  of 
  the 
  wheels 
  

  

  x 
  The 
  method 
  of 
  deducing 
  equations 
  (39) 
  and 
  (40) 
  may 
  be 
  found 
  in 
  

   Mullin's 
  Irrigation 
  Manual, 
  1890, 
  pp. 
  11, 
  12, 
  138, 
  139, 
  171, 
  172. 
  

  

  