﻿ISO 
  

  

  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  [2] 
  

  

  block 
  of 
  wood 
  perforated 
  so 
  as 
  to 
  allow 
  tlie 
  instruments 
  to 
  pass 
  through 
  

   and 
  to 
  hold 
  them 
  iu 
  place. 
  By 
  agitating 
  this 
  stirrer, 
  which 
  was 
  covered 
  

   with 
  muslin 
  to 
  guard 
  against 
  breakage 
  of 
  the 
  thermometers, 
  up 
  and 
  

   down, 
  the 
  water 
  contained 
  in 
  the 
  vessel 
  was 
  thoroughly 
  mixed, 
  and 
  an 
  

   uniform 
  temperature 
  obtained 
  throughout. 
  

  

  >iii]!arii»«*,].M\ 
  

  

  This 
  simple 
  contrivance 
  answers 
  very 
  well 
  for 
  ordinary 
  thermometers, 
  

   the 
  bulbs 
  of 
  which 
  are 
  exposed 
  directly 
  to 
  the 
  water, 
  but 
  admits 
  only 
  

   two 
  or 
  three 
  instruments 
  at 
  a 
  time, 
  owing 
  to 
  the 
  comparatively 
  small 
  

   volume 
  of 
  water 
  which 
  it 
  contains. 
  A 
  square 
  aquarium 
  tank, 
  with 
  plate 
  

   glass 
  sides 
  and 
  slate 
  bottom, 
  was 
  therefore 
  procured 
  from 
  E. 
  W. 
  Taxis, 
  

   of 
  Philadelphia 
  (received 
  February 
  20, 
  1881). 
  This 
  tank 
  is 
  18 
  inches 
  

   square 
  by 
  1G 
  inches 
  high, 
  and 
  contains 
  about 
  22gallonsof 
  water. 
  Within 
  

   the 
  tank 
  is 
  a 
  circular 
  brass 
  frame, 
  to 
  which 
  a 
  large 
  number 
  of 
  thermom- 
  

   eters 
  may 
  be 
  attached 
  at 
  once, 
  and 
  which 
  may 
  be 
  revolved 
  about 
  a 
  cen- 
  

   tral 
  spindle 
  by 
  means 
  of 
  a 
  winch-handle 
  at 
  the 
  top. 
  The 
  water 
  is 
  stirred 
  

   to 
  an 
  uniform 
  temperature 
  by 
  turning 
  the 
  winch-handle, 
  and 
  is 
  in 
  suffi- 
  

   ciently 
  large 
  volume 
  to 
  maintain 
  a 
  sensibly 
  constant 
  temperature 
  for 
  

   five 
  minutes. 
  The 
  temperatures 
  of 
  the 
  thermometers 
  to 
  be 
  compared 
  

   and 
  of 
  the 
  standard 
  can 
  be 
  read 
  in 
  this 
  apparatus 
  through 
  the 
  plate- 
  

   glass 
  sides, 
  and 
  a 
  full 
  series 
  of 
  readings, 
  from 
  32° 
  to 
  100°, 
  can 
  be 
  taken 
  

   without 
  removing 
  the 
  thermometers 
  from 
  the 
  frame. 
  

  

  For 
  the 
  "zero 
  point," 
  or 
  32° 
  F., 
  the 
  thermometers 
  to 
  be 
  tested 
  arc 
  

   immersed 
  in 
  finely 
  broken 
  ice, 
  contained 
  in 
  large 
  glass 
  percolators, 
  12 
  

   inches 
  wide 
  by 
  12 
  inches 
  deep, 
  with 
  a 
  small 
  opening 
  at 
  the 
  bottom 
  for 
  

   the 
  escape 
  of 
  water 
  as 
  fast 
  as 
  the 
  ice 
  melts. 
  These 
  percolators 
  are 
  sup- 
  

   ported 
  upon 
  suitable 
  iron 
  tripods, 
  and 
  will 
  hold 
  eight 
  thermometers 
  each, 
  

   without 
  so 
  crowding 
  the 
  instruments 
  that 
  one 
  shall 
  affect 
  another. 
  

  

  