﻿56 
  

  

  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  The 
  troughs 
  are 
  supported 
  by 
  a 
  suitable 
  framework 
  at 
  a 
  couveuient 
  

   height 
  from 
  the 
  ground 
  aud 
  arranged 
  in 
  pairs 
  with 
  their 
  heads 
  against 
  

   a 
  long 
  feed-trough, 
  constructed 
  of 
  pine 
  boards 
  and 
  perforated 
  on 
  the 
  

   side 
  by 
  the 
  feed-pipes, 
  over 
  each 
  of 
  which 
  is 
  a 
  capacious 
  screen 
  to 
  pre- 
  

   vent 
  clogging 
  by 
  leaves 
  or 
  other 
  floating 
  debris. 
  A 
  frame 
  6 
  by 
  12 
  

   inches, 
  covered 
  on 
  its 
  outer 
  side 
  by 
  wire-cloth 
  of 
  ^ 
  inch 
  square 
  mesh, 
  

   answers 
  the 
  purpose 
  of 
  a 
  screen 
  so 
  well 
  that 
  water 
  from 
  an 
  ordinary 
  

   brook 
  can 
  be 
  admitted 
  to 
  the 
  feed-trough 
  without 
  previous 
  filtering 
  or 
  

   screening 
  and 
  with 
  little 
  or 
  no 
  danger 
  of 
  a 
  stoppage 
  of 
  water 
  in 
  any 
  

   of 
  the- 
  fish-troughs. 
  Such 
  screens 
  over 
  the 
  feed-pipes 
  might 
  be 
  made 
  

   the 
  sole 
  dependence, 
  were 
  it 
  not 
  that 
  the 
  labor 
  attending 
  their 
  cleaning 
  

   would 
  be 
  greater 
  than 
  that 
  required 
  by 
  a 
  separate 
  filter 
  or 
  screen. 
  

  

  CoThduxt 
  to 
  lower 
  level. 
  

  

  )| 
  Fish 
  trough 
  

  

  sf, 
  

  

  Scale 
  or 
  feet. 
  

  

  Stand 
  of 
  Troughs 
  for 
  Rearing 
  Atlantic 
  Salmon. 
  

  

  The 
  system 
  represented 
  here 
  by 
  12 
  troughs 
  in 
  two 
  series 
  may 
  be 
  

   extended 
  to 
  many 
  hundreds 
  of 
  troughs 
  in 
  four 
  (or 
  more) 
  series, 
  each 
  

   series 
  on 
  a 
  different 
  level 
  and 
  receiving 
  water 
  from 
  the 
  series 
  next 
  

   above, 
  the 
  fall 
  from 
  one 
  to 
  another 
  being 
  about 
  4 
  feet. 
  In 
  the 
  drawing 
  

   the 
  series 
  of 
  6 
  troughs 
  on 
  the 
  left 
  is 
  supplied 
  with 
  water 
  directly 
  from 
  

   the 
  upper 
  "feed-trough" 
  (i. 
  e., 
  supply-trough), 
  and 
  they 
  discharge 
  into 
  

   a 
  catch-trough, 
  from 
  which 
  the 
  water 
  is 
  carried 
  to 
  the 
  supply-trough 
  

   ("feed-trough") 
  of 
  the 
  lower 
  level. 
  If 
  the 
  aqueduct 
  supplies 
  more 
  

   water 
  than 
  the 
  upper 
  series 
  of 
  troughs 
  can 
  use, 
  the 
  surplus 
  passes 
  by 
  

   way 
  of 
  the 
  "overflow" 
  directly 
  to 
  the 
  catch-trough 
  and 
  thence 
  to 
  the 
  

   supply-trough 
  of 
  the 
  second 
  series. 
  With 
  a 
  fall 
  of 
  4 
  feet, 
  the 
  catch- 
  

   trough 
  and 
  the 
  conduits 
  that 
  lead 
  from 
  it 
  are 
  below 
  the 
  walks 
  which 
  

   give 
  access 
  to 
  the 
  troughs 
  on 
  both 
  sides 
  and 
  at 
  the 
  lower 
  end. 
  

  

  The 
  number 
  of 
  fish 
  assigned 
  to 
  a 
  single 
  trough 
  is 
  ordinarily 
  2,000, 
  

   and 
  the 
  volume 
  of 
  water 
  given 
  them 
  is 
  commonly 
  5 
  gallons 
  per 
  minute. 
  

   Generally 
  the 
  water 
  is 
  used 
  but 
  once 
  in 
  troughs 
  and 
  is 
  discharged 
  

  

  