﻿MANUAL 
  OF 
  FISH-CULTURE. 
  37 
  

  

  in 
  other 
  respects 
  will 
  this 
  answer, 
  and 
  even 
  then 
  it 
  is 
  only 
  admissible 
  

   where 
  there 
  is 
  an 
  ample 
  supply 
  of 
  aerated 
  water 
  and 
  the 
  troughs 
  are 
  

   very 
  short 
  and 
  there 
  is 
  absolutely 
  no 
  danger 
  of 
  inundation; 
  and 
  this 
  

   fall 
  has 
  the 
  disadvantages 
  of 
  the 
  impracticability 
  of 
  introducing 
  any 
  

   aerating 
  apparatus 
  and 
  the 
  necessity 
  of 
  having 
  the 
  troughs 
  sunk 
  below 
  

   the 
  floor 
  of 
  the 
  hatching-house, 
  which 
  makes 
  the 
  work 
  of 
  attending 
  the 
  

   eggs 
  and 
  fish 
  very 
  laborious. 
  

  

  A 
  fall 
  of 
  1 
  foot 
  will 
  do 
  fairly 
  well 
  if 
  there 
  is 
  entire 
  safety 
  from 
  inun- 
  

   dation, 
  as 
  this 
  will 
  permit 
  the 
  troughs 
  being 
  placed 
  on 
  the 
  floor, 
  which 
  

   is 
  a 
  better 
  position 
  than 
  below 
  it, 
  though 
  still 
  an 
  inconvenient 
  one, 
  

   and 
  some 
  of 
  the 
  simpler 
  aerating 
  devices 
  can 
  be 
  introduced. 
  Better 
  is 
  

   a 
  fall 
  of 
  3 
  feet, 
  and 
  far 
  better 
  a 
  fall 
  of 
  6 
  feet. 
  The 
  latter 
  permits 
  the 
  

   placing 
  of 
  the 
  lowest 
  hatching-troughs 
  2 
  feet 
  above 
  the 
  floor 
  and 
  leaves 
  

   ample 
  room 
  for 
  complete 
  aeration. 
  The 
  necessities 
  of 
  the 
  case 
  are 
  

   dependent 
  largely 
  upon 
  the 
  volume 
  and 
  character 
  of 
  the 
  water, 
  and 
  

   if 
  there 
  is 
  plenty 
  of 
  it, 
  well 
  aerated 
  before 
  reaching 
  the 
  hatching-house, 
  

   there 
  is 
  no 
  occasion, 
  in 
  a 
  small 
  establishment, 
  of 
  additional 
  aeration 
  in 
  

   the 
  house, 
  and 
  therefore 
  no 
  need 
  of 
  more 
  than 
  3 
  feet 
  fall. 
  

  

  Inspection 
  of 
  the 
  premises 
  at 
  time 
  of 
  floods 
  will 
  suggest 
  the 
  safe- 
  

   guards 
  necessary 
  to 
  j)rovide 
  against 
  inundation. 
  If 
  located 
  by 
  a 
  brook- 
  

   side, 
  the 
  hatching-house 
  should 
  not 
  obtrude 
  too 
  much 
  on 
  the 
  channel, 
  

   and 
  below 
  the 
  house 
  there 
  should 
  be 
  an 
  ample 
  outlet 
  for 
  everything 
  that 
  

   may 
  come. 
  By 
  clearing 
  out 
  and 
  enlarging 
  a 
  natural 
  watercourse 
  much 
  

   can 
  often 
  be 
  done 
  to 
  improve 
  an 
  originally 
  bad 
  site. 
  

  

  In 
  a 
  cold 
  climate 
  it 
  is 
  an 
  excellent 
  plan 
  to 
  have 
  the 
  hatching- 
  house 
  

   partly 
  under 
  ground, 
  for 
  greater 
  protection 
  against 
  outside 
  cold. 
  When 
  

   spring 
  water 
  is 
  used 
  there 
  is 
  rarely 
  any 
  trouble, 
  even 
  in 
  a 
  cool 
  house, 
  

   from 
  the 
  formation 
  of 
  ice 
  in 
  the 
  troughs; 
  but 
  water 
  from 
  lake, 
  river, 
  or 
  

   brook 
  is, 
  in 
  the 
  latitude 
  of 
  the 
  northern 
  tier 
  of 
  States, 
  so 
  cold 
  in 
  winter 
  

   that 
  if 
  the 
  air 
  of 
  the 
  hatching-house 
  is 
  allowed 
  to 
  remain 
  much 
  below 
  

   the 
  freezing-point 
  ice 
  will 
  form 
  in 
  the 
  troughs 
  and 
  on 
  the 
  floor 
  to 
  such 
  

   an 
  extent 
  as 
  to 
  be 
  a 
  serious 
  annoyance, 
  and 
  if 
  not 
  watched 
  will 
  form 
  

   in 
  the 
  hatching-troughs 
  so 
  deeply 
  as 
  to 
  freeze 
  the 
  eggs 
  and 
  destroy 
  

   them. 
  Stoves 
  are 
  needed 
  in 
  sach 
  climates 
  to 
  warm 
  the 
  air 
  enough 
  

   for 
  the 
  comfort 
  of 
  the 
  attendants: 
  but 
  the 
  house 
  should 
  be 
  so 
  located 
  

   and 
  constructed 
  that 
  it 
  may 
  be 
  left 
  without 
  a 
  fire 
  for 
  weeks 
  without 
  

   any 
  dangerous 
  accumulation 
  of 
  ice, 
  and 
  if 
  the 
  site 
  does 
  not 
  permit 
  of 
  

   building 
  the 
  house 
  partly 
  under 
  ground 
  the 
  walls 
  must 
  be 
  thoroughly 
  

   constructed 
  and 
  banked 
  well 
  with 
  earth, 
  sawdust, 
  or 
  other 
  material. 
  

   In 
  warmer 
  climates 
  no 
  trouble 
  will 
  be 
  experienced 
  from 
  this 
  source. 
  

  

  DAMS 
  AND 
  CONDUITS. 
  

  

  The 
  requisite 
  head 
  of 
  water 
  can 
  often 
  be 
  had 
  by 
  throwing 
  a 
  dam 
  

   across 
  the 
  stream 
  and 
  locating 
  the 
  hatching 
  house 
  close 
  to 
  it. 
  The 
  

   dam 
  will 
  form 
  a 
  small 
  pond, 
  which 
  will 
  serve 
  the 
  triple 
  purpose 
  of 
  cool- 
  

   ing, 
  aerating, 
  and 
  cleansing 
  the 
  water. 
  But 
  unless 
  the 
  character 
  of 
  

   the 
  bed 
  and 
  banks 
  of 
  the 
  stream 
  are 
  such 
  as 
  to 
  preclude 
  any 
  danger 
  

  

  