﻿MANUAL 
  OF 
  FISH-CULTURE. 
  43 
  

  

  elapse 
  between 
  the 
  cleauings. 
  The 
  wire 
  — 
  even 
  galvanized 
  — 
  rusts 
  out 
  

   in 
  two 
  or 
  three 
  years, 
  and 
  lately 
  the 
  coarser 
  screens 
  have 
  been 
  made 
  

   of 
  slender 
  rods 
  of 
  oak, 
  which 
  will 
  undoubtedly 
  prove 
  more 
  durable. 
  

  

  None 
  of 
  the 
  filters 
  described 
  will 
  intercept 
  the 
  finest 
  sediment, 
  and 
  

   the 
  water 
  is 
  finally 
  passed 
  through 
  a 
  capacious 
  wooden 
  reservoir, 
  30 
  

   feet 
  long, 
  8 
  feet 
  wide, 
  and 
  5i 
  feet 
  deep, 
  before 
  it 
  reaches 
  the 
  troughs. 
  

   This 
  answers 
  the 
  purpose 
  well 
  for 
  the 
  amount 
  of 
  water 
  supplied 
  by 
  the 
  

   filter 
  last 
  described 
  (about 
  500 
  gallons 
  per 
  minute) 
  and 
  is 
  regarded 
  as 
  

   well 
  worth 
  having, 
  though 
  even 
  this 
  will 
  not 
  insure 
  limpidity 
  in 
  the 
  

   water 
  when 
  the 
  brook 
  is 
  swollen 
  by 
  rains. 
  

  

  It 
  may 
  be 
  mentioned 
  that 
  this 
  reservoir 
  is 
  kept 
  brimful 
  at 
  all 
  times, 
  

   so 
  that 
  all 
  portions 
  of 
  the 
  woodwork, 
  except 
  the 
  railing 
  surrounding 
  it, 
  

   are 
  kept 
  continuously 
  wet 
  and 
  thus 
  insured 
  against 
  decay 
  for 
  a 
  very 
  

   long 
  period 
  of 
  years. 
  

  

  CRAIG 
  BROOK 
  HATCHERY 
  AND 
  ITS 
  EQUIPMENT. 
  

  

  The 
  Craig 
  Brook 
  hatchery 
  derives 
  its 
  water 
  supply 
  from 
  the 
  brook, 
  

   which 
  has 
  its 
  source 
  in 
  Craig 
  Pond, 
  but 
  which 
  receives 
  in 
  the 
  lower 
  

   part 
  of 
  its 
  course 
  many 
  copious 
  springs. 
  This 
  spring 
  water 
  has 
  some 
  

   advantages, 
  but 
  possesses 
  the 
  serious 
  disadvantage 
  of 
  such 
  high 
  tem- 
  

   perature 
  in 
  winter 
  as 
  to 
  unduly 
  hasten 
  the 
  development 
  of 
  the 
  eggs, 
  

   causing 
  them 
  to 
  hatch 
  early 
  and 
  necessitating 
  shipments 
  of 
  eggs 
  in 
  

   December. 
  

  

  Accordingly, 
  an 
  aqueduct 
  from 
  a 
  point 
  on 
  the 
  brook 
  above 
  the 
  springs 
  

   brings 
  to 
  the 
  hatchery 
  a 
  supply 
  of 
  cold 
  water 
  for 
  winter 
  use, 
  in 
  which 
  

   eggs 
  taken 
  the 
  first 
  of 
  November 
  will 
  not 
  hatch 
  until 
  the 
  following 
  

   April. 
  This 
  is 
  important, 
  as, 
  if 
  the 
  i)roduct 
  of 
  the 
  season's 
  hatching 
  is 
  

   to 
  be 
  liberated 
  as 
  fry, 
  the 
  late 
  date 
  of 
  hatching 
  will 
  bring 
  them 
  to 
  the 
  

   feeding 
  stage 
  about 
  the 
  time 
  when 
  suitable 
  food 
  abounds 
  in 
  open 
  waters, 
  

   and 
  if 
  they 
  are 
  to 
  be 
  reared 
  it 
  is 
  well 
  to 
  shorten 
  up 
  the 
  sac 
  stage 
  and 
  

   to 
  have 
  the 
  early 
  feeding 
  stage 
  fall 
  at 
  a 
  date 
  when 
  the 
  temperature 
  of 
  

   the 
  water 
  is 
  rapidly 
  rising, 
  which 
  will 
  get 
  the 
  fish 
  (piickly 
  through 
  

   that 
  most 
  difficult 
  of 
  all 
  stages 
  of 
  growth. 
  

  

  The 
  aqueduct 
  is 
  about 
  1,600 
  feet 
  long, 
  with 
  a 
  bore 
  4i 
  inches, 
  and 
  has 
  

   a 
  nearly 
  uniform 
  descent 
  and 
  total 
  freedom 
  from 
  depressions, 
  and 
  is 
  

   from 
  end 
  to 
  end 
  one 
  single 
  piece 
  of 
  cement 
  concrete. 
  It 
  delivers 
  to 
  the 
  

   hatchery 
  about 
  100 
  gallons 
  of 
  water 
  per 
  minute, 
  which 
  is 
  sufiQcient 
  for 
  

   the 
  development 
  of 
  4,000,000 
  eggs, 
  and 
  possibly 
  many 
  more. 
  It 
  was 
  

   built 
  in 
  place 
  around 
  a 
  slightly 
  tapering 
  core, 
  which 
  was 
  drawn 
  forward 
  

   as 
  fast 
  as 
  the 
  mortar 
  set, 
  and 
  it 
  has 
  now 
  done 
  good 
  service 
  for 
  seven- 
  

   teen 
  years. 
  By 
  this 
  means 
  the 
  temperature 
  of 
  the 
  hatchery 
  water 
  is 
  

   maintained 
  3° 
  below 
  that 
  of 
  the 
  brook 
  modified 
  by 
  the 
  springs. 
  During 
  

   the 
  five 
  months 
  from 
  November 
  1, 
  1895, 
  to 
  April 
  1, 
  1896, 
  the 
  mean 
  tem- 
  

   perature 
  in 
  the 
  hatchery 
  was 
  36.65° 
  F. 
  

  

  