﻿[19] 
  REPORT 
  ON 
  THERMOMETERS. 
  203 
  

  

  In 
  5 
  minutes 
  from 
  62° 
  to 
  35.5° 
  26. 
  5 
  

  

  In 
  6 
  minutes 
  from 
  58° 
  to 
  43° 
  15.0 
  

  

  In 
  7 
  minutes 
  from 
  68° 
  to 
  38.8° 
  29.2 
  

  

  In 
  8 
  minutes 
  from 
  58° 
  to 
  37° 
  21.0 
  

  

  In 
  9 
  minutes 
  from 
  50° 
  to 
  36° 
  14. 
  

  

  In 
  10 
  minutes 
  from 
  60° 
  to 
  37° 
  23.0 
  

  

  In 
  10 
  minutes 
  from 
  72° 
  to 
  32.6° 
  39. 
  4 
  

  

  In 
  1 
  1 
  minutes 
  from 
  58.5° 
  to 
  32.4° 
  20. 
  1 
  

  

  In 
  15.5 
  minutes 
  from 
  60° 
  to 
  32.4° 
  27.6 
  

  

  The 
  change 
  is 
  rather 
  irregular, 
  depending 
  somewhat 
  upon 
  the 
  tem- 
  

   perature 
  marked 
  by 
  the 
  thermometer 
  at 
  the 
  beginning 
  of 
  each 
  experi- 
  

   ment, 
  and 
  partly 
  upon 
  the 
  more 
  or 
  less 
  close 
  coaptation 
  of 
  the 
  melting 
  

   ice 
  to 
  the 
  outer 
  case 
  of 
  the 
  thermometer. 
  The 
  rapidity 
  with 
  which 
  the 
  

   instrument 
  is 
  overset 
  may 
  also 
  sometimes 
  influence 
  the 
  position 
  of 
  the 
  

   breaking 
  point, 
  as 
  in 
  the 
  following 
  instance: 
  Fish 
  Commission 
  No. 
  5157 
  

   (maker's 
  No. 
  52752), 
  immersed 
  in 
  water 
  at 
  45.3°, 
  overturned 
  by 
  a 
  quick 
  

   movement 
  read 
  45.6°, 
  by 
  slow 
  movement 
  46.5°. 
  In 
  water 
  at 
  46°, 
  over- 
  

   turned 
  by 
  quick 
  movement 
  it 
  read 
  46.1°, 
  by 
  slow 
  movement 
  46.3°. 
  

   Even 
  when 
  compared 
  without 
  the 
  investing 
  metallic 
  case 
  now 
  used 
  at 
  

   sea, 
  it 
  seems 
  that 
  the 
  reading 
  cannot 
  be 
  safely 
  depended 
  upon 
  with 
  less 
  

   than 
  ten 
  minutes 
  exposure, 
  in 
  laboratory 
  comparisons. 
  In 
  practice, 
  at 
  

   sea, 
  since 
  the 
  thermometers 
  are 
  changing 
  on 
  their 
  way 
  down, 
  and 
  the 
  

   water 
  in 
  contact 
  with 
  them 
  is 
  continually 
  renewed, 
  it 
  is 
  probable 
  that 
  

   a 
  less 
  time 
  may 
  serve. 
  The 
  use 
  of 
  self-oversetting 
  cases 
  insures 
  uni- 
  

   formity 
  in 
  the 
  quickness 
  of 
  the 
  turn. 
  The 
  present 
  rule 
  in 
  the 
  work 
  of 
  

   the 
  Commission 
  is 
  to 
  leave 
  the 
  thermometers 
  down 
  for 
  ten 
  minutes. 
  

  

  An 
  annoying 
  defect 
  in 
  construction, 
  which 
  might 
  easily 
  be 
  remedied, 
  

   is 
  the 
  wide 
  variation 
  in 
  graduation 
  on 
  the 
  scales. 
  In 
  twelve 
  thermome- 
  

   ters 
  of 
  this 
  pattern, 
  compared 
  September 
  12, 
  1884, 
  for 
  example, 
  the 
  

   range 
  of 
  graduation 
  varied 
  between 
  63° 
  (+32° 
  to 
  +95°), 
  and 
  112° 
  ( 
  — 
  25° 
  

   to 
  +87°). 
  The 
  degree 
  spaces 
  in 
  the 
  first-named 
  instrument 
  are 
  nearly 
  

   twice 
  as 
  wide 
  as 
  those 
  in 
  the 
  last, 
  and, 
  since 
  there 
  is 
  no 
  pointing 
  to 
  

   fractions 
  of 
  a 
  degree, 
  estimations 
  of 
  fractional 
  parts 
  are 
  made 
  much 
  

   more 
  difficult 
  by 
  these 
  inequalities 
  in 
  spacing, 
  the 
  eye 
  gaining 
  nothing 
  

   by 
  practice 
  with 
  one 
  thermometer 
  when 
  another 
  is 
  substituted 
  for 
  it. 
  

  

  The 
  Negretti-Zambra 
  thermometer, 
  as 
  at 
  present 
  constructed, 
  leaves 
  

   little 
  to 
  be 
  wished 
  for 
  as 
  a 
  deep-sea 
  temperature 
  recorder, 
  beyond 
  some 
  

   improvement 
  in 
  the 
  details 
  of 
  construction. 
  The 
  mode 
  of 
  protection 
  

   absolutely 
  does 
  away 
  with 
  pressure 
  error, 
  and 
  the 
  use 
  of 
  mercury 
  in 
  

   the 
  bulb-case 
  has 
  raised 
  its 
  sensitiveness 
  to 
  a 
  point 
  considerably 
  above 
  

   that 
  of 
  the 
  Miller-Casella. 
  With 
  a 
  little 
  greater 
  certainty 
  in 
  the 
  for- 
  

   mation 
  of 
  the 
  column-breaking 
  contrivance, 
  and 
  a 
  good 
  deal 
  more 
  uni- 
  

   formity 
  in 
  the 
  graduation 
  of 
  the 
  stem, 
  there 
  need 
  be 
  no 
  fear 
  of 
  erro- 
  

   neous 
  indications 
  from 
  any 
  depth 
  that 
  the 
  glass 
  protecting 
  tube 
  will 
  

   stand. 
  With 
  due 
  care 
  in 
  noting 
  untrustworthy 
  instruments 
  by 
  labora- 
  

   tory 
  comparisons, 
  there 
  should 
  never 
  be 
  any 
  possibility 
  of 
  recording 
  an 
  

  

  