﻿200 
  

  

  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  [16] 
  

  

  pivoted 
  near 
  its 
  center, 
  upon 
  a 
  frame, 
  and 
  a 
  small 
  rudder 
  or 
  fan 
  was 
  

   geared 
  to 
  the 
  pivot. 
  This 
  rudder 
  pointed 
  upward 
  during 
  the 
  descent 
  

   of 
  the 
  instrument, 
  and 
  downward 
  during 
  its 
  ascent, 
  making 
  a 
  half 
  revo- 
  

   lution 
  at 
  the 
  moment 
  of 
  reversing 
  the 
  di- 
  

   rection 
  of 
  motion, 
  which 
  produced 
  a 
  com- 
  

   plete 
  revolution 
  of 
  the 
  thermometer. 
  The 
  

   broken 
  part 
  of 
  the 
  mercurial 
  column 
  in 
  

   the 
  tube 
  dropped 
  first 
  into 
  the 
  enlarge- 
  

   ment 
  at 
  the 
  bend, 
  and 
  then 
  passed 
  over 
  

   into 
  the 
  other 
  leg, 
  where 
  its 
  height, 
  and 
  

   the 
  temperature 
  at 
  the 
  time 
  of 
  reversal, 
  

   could 
  be 
  read 
  on 
  the 
  scale. 
  The 
  bulb 
  was 
  

   protected 
  as 
  in 
  the 
  Miller-Casella 
  instru- 
  

   ment. 
  

  

  Subsequently 
  a 
  frame 
  was 
  constructed 
  

   carrying 
  a 
  screw-propeller 
  (Fig. 
  10), 
  which 
  

   revolved 
  freely 
  during 
  the 
  descent 
  of 
  the 
  

   instrument 
  but 
  engaged 
  a 
  train 
  of 
  ratchet- 
  

   work 
  as 
  soon 
  as 
  the 
  direction 
  was 
  changed 
  

   to 
  ascent, 
  and 
  .caused 
  the 
  thermometer 
  to 
  

   revolve 
  once 
  upon 
  an 
  axis 
  near 
  its 
  center, 
  

   first 
  to 
  bulb 
  uppermost, 
  catching 
  the 
  sep- 
  

   arated 
  column 
  of 
  mercury 
  in 
  the 
  bend 
  of 
  

   the 
  siphon, 
  and 
  then 
  to 
  bulb 
  downward 
  

   again, 
  allowing 
  the 
  mercury 
  to 
  flow 
  into 
  

   the 
  other 
  limb 
  of 
  the 
  tube, 
  where 
  the 
  

   temperature 
  was 
  read. 
  A 
  specimen 
  of 
  

   this 
  form 
  was 
  purchased 
  by 
  the 
  Coast 
  

   Survey 
  and 
  tried 
  by 
  the 
  Blake 
  in 
  1875, 
  

   "but 
  it 
  was 
  so 
  cumbersome, 
  expensive 
  (the 
  

   advertised 
  price 
  was 
  10 
  guineas), 
  and 
  left 
  

   so 
  much 
  open 
  to 
  doubt 
  in 
  its 
  indications, 
  

   that 
  it 
  was 
  reported 
  on 
  adversely 
  to 
  the 
  

   Superintendent."* 
  Several 
  were 
  also 
  

   sent 
  out 
  to 
  the 
  Challenger 
  and 
  tried 
  dur- 
  

   ing 
  the 
  cruise. 
  At 
  first, 
  Staff 
  Commander 
  

   Tizard 
  reports 
  thatt 
  "it 
  was 
  found 
  in 
  

   practice 
  that 
  the 
  propeller 
  being 
  arrested 
  

   over 
  the 
  thermometer, 
  after 
  it 
  had 
  over- 
  

   turned, 
  brought 
  such 
  a 
  strain 
  on 
  the 
  cog- 
  

   wheel 
  as 
  to 
  twist 
  it 
  off 
  its 
  spindle 
  and 
  

   cause 
  its 
  loss." 
  This 
  difficulty 
  was 
  reme- 
  

   died 
  by 
  the 
  chief 
  engineer 
  of 
  the 
  Chal- 
  

   lenger, 
  Mr. 
  Ferguson, 
  but 
  the 
  record 
  of 
  

   the 
  instruments 
  was 
  not 
  found 
  to 
  be 
  satisfactory. 
  Four 
  that 
  were 
  tried 
  

  

  Fig. 
  10.— 
  Early 
  form 
  of 
  Negretti-Zambra 
  

   self-registing 
  deep-sea 
  thermometer. 
  

  

  Sigsbee, 
  op. 
  cit., 
  p. 
  114. 
  

  

  t 
  Narrative, 
  vol. 
  1, 
  p. 
  89. 
  

  

  