﻿WATEE-POWEK 
  DEVELOPMENT 
  IN 
  THE 
  MISSISSIPPI. 
  17 
  

  

  the 
  boat 
  passes 
  over 
  the 
  front 
  wall 
  of 
  the 
  lock 
  which 
  is 
  covered 
  by 
  8 
  

   to 
  14 
  feet 
  of 
  water, 
  according 
  to 
  the 
  stage 
  of 
  the 
  lake. 
  

  

  It 
  should 
  be 
  remarked 
  that 
  the 
  lower 
  gates, 
  which 
  are 
  of 
  heavy 
  

   steel 
  truss 
  construction, 
  swing 
  open, 
  while 
  the 
  upper 
  gate 
  is 
  of 
  a 
  new 
  

   submerging 
  type. 
  This 
  gate 
  is 
  a 
  heavy 
  steel 
  truss 
  containing 
  air 
  

   chambers 
  below 
  and 
  works 
  up 
  and 
  down 
  in 
  vertical 
  slots 
  of 
  steel. 
  

   There 
  is 
  also 
  an 
  emergency 
  gate 
  a 
  short 
  distance 
  in 
  front 
  of 
  the 
  regu- 
  

   lar 
  upper 
  gate 
  which 
  may 
  be 
  used 
  when 
  necessary 
  to 
  repair 
  the 
  latter. 
  

  

  It 
  will 
  be 
  inferred 
  from 
  the 
  above 
  description 
  that 
  the 
  fish 
  would 
  

   not 
  be 
  likely 
  to 
  enter 
  the 
  lock 
  from 
  below 
  during 
  the 
  process 
  of 
  

   emptying, 
  since 
  to 
  do 
  so 
  would 
  be 
  to 
  pass 
  through 
  the 
  deeply 
  sub- 
  

   merged 
  sharp-angle, 
  culverts 
  or 
  tunnels 
  out 
  of 
  which 
  the 
  water 
  is 
  

   discharging 
  apparently 
  at 
  enormous 
  velocity. 
  Correspondingly 
  it 
  

   is 
  not 
  to 
  be 
  expected 
  that 
  they 
  would 
  gain 
  the 
  upper 
  lake 
  from 
  the 
  

   lock 
  dm^mg 
  the 
  process 
  of 
  fiUing, 
  since 
  to 
  do 
  so 
  entails 
  passing 
  down 
  

   through 
  the 
  same 
  tunnels 
  against 
  the 
  rush 
  of 
  water 
  under 
  a 
  40-foot 
  

   head. 
  It 
  is 
  possible 
  that 
  a 
  few 
  might 
  make 
  their 
  exit 
  in 
  this 
  way 
  

   after 
  the 
  lock 
  is 
  nearly 
  filled. 
  

  

  It 
  is 
  also 
  clear 
  from 
  the 
  description 
  of 
  the 
  working 
  of 
  the 
  lock 
  that 
  

   the 
  gate 
  above 
  is 
  not 
  submerged 
  except 
  when 
  the 
  lock 
  is 
  full, 
  nor 
  are 
  

   the 
  gates 
  below 
  opened 
  except 
  when 
  the 
  lock 
  is 
  empty. 
  In 
  other 
  

   words, 
  there 
  is 
  no 
  ingress 
  or 
  egress 
  through 
  the 
  gates 
  for 
  fish 
  that 
  are 
  

   working 
  upstream 
  except 
  when 
  the 
  water 
  in 
  the 
  lock 
  is 
  stationary, 
  

   which 
  is 
  to 
  say, 
  when 
  ascending 
  fish 
  are 
  least 
  tempted 
  to 
  move 
  in 
  

   that 
  direction. 
  

  

  Another 
  feature 
  of 
  the 
  lock 
  construction 
  is 
  significant. 
  The 
  upper 
  

   opening 
  of 
  the 
  lock 
  does 
  not 
  extend 
  down 
  to 
  the 
  bottom, 
  but 
  is 
  

   largely 
  closed 
  from 
  below 
  by 
  a 
  solid 
  concrete 
  wall 
  over 
  30 
  feet 
  high. 
  

   (PI. 
  vi). 
  A 
  fish 
  entering 
  the 
  empty 
  lock 
  from 
  below 
  finds 
  8 
  feet 
  

   of 
  water 
  at 
  the 
  lowest 
  stage 
  of 
  the 
  river; 
  leaving 
  the 
  full 
  lock 
  above 
  

   it 
  finds 
  8 
  to 
  14 
  feet 
  of 
  water 
  between 
  the 
  top 
  of 
  the 
  submerged 
  gate 
  

   and 
  the 
  lake 
  surface 
  according 
  to 
  the 
  stage 
  of 
  the 
  lake. 
  To 
  find 
  its 
  

   way 
  out, 
  therefore, 
  it 
  must 
  make 
  a 
  vertical 
  rise 
  of 
  25 
  to 
  35 
  feet, 
  

   without 
  the 
  presence 
  of 
  any 
  definite 
  current 
  to 
  direct 
  its 
  movements, 
  

   or 
  else, 
  as 
  before 
  mentioned, 
  it 
  may 
  seek 
  its 
  way 
  out 
  through 
  the 
  

   deep 
  tunnels 
  beneath. 
  How 
  wiU 
  this 
  head 
  wall 
  affect 
  the 
  movements 
  

   of 
  bottom-loving 
  fish 
  ? 
  

  

  Parenthetically, 
  it 
  may 
  be 
  said 
  that 
  the 
  effect 
  of 
  the 
  unwonted 
  

   variation 
  in 
  pressure 
  within 
  the 
  lock 
  may 
  have 
  a 
  real 
  (but 
  quite 
  

   unknown) 
  influence 
  on 
  the 
  movement 
  of 
  fishes. 
  The 
  depth 
  of 
  water 
  

   in 
  the 
  lock 
  varies 
  from 
  8 
  to 
  48 
  feet. 
  The 
  possible 
  demoralization 
  of 
  

   the 
  fish 
  by 
  the 
  turbulence 
  of 
  waters 
  suddenly 
  boiling 
  up 
  fi'om 
  below 
  

   under 
  a 
  30 
  to 
  40 
  foot 
  head 
  is 
  perhaps 
  uncertain, 
  though 
  we 
  may 
  

   infer 
  that 
  its 
  effect 
  would 
  not 
  be 
  the 
  happiest. 
  

  

  