﻿Duane 
  and 
  Lory 
  — 
  Electrical 
  Thermostat. 
  

  

  181 
  

  

  The 
  whole 
  system 
  of 
  tubing 
  was 
  placed 
  in 
  the 
  bath 
  with 
  the 
  

   planes 
  of 
  the 
  rectangles 
  horizontal 
  and 
  the 
  tube 
  C 
  vertical. 
  

   The 
  portion 
  G 
  D 
  E 
  is 
  the 
  regulating 
  device. 
  After 
  the 
  tubes 
  

   had 
  been 
  tilled 
  through 
  a 
  small 
  hole 
  in 
  the 
  top 
  of 
  the 
  tube 
  E 
  a 
  

   brass 
  cap 
  was 
  screwed 
  on 
  the 
  end 
  of 
  E, 
  pressing 
  a 
  small 
  disk 
  

   of 
  lead 
  tight 
  down 
  over 
  the 
  hole. 
  This 
  formed 
  a 
  perfectly 
  

   air-tight 
  stopper. 
  The 
  form 
  of 
  the 
  stopper 
  and 
  regulating 
  

   device 
  finally 
  adopted 
  is 
  shown 
  in 
  fig. 
  2. 
  The 
  portions 
  of 
  the 
  

   tube 
  marked 
  a 
  c 
  and 
  d 
  were 
  of 
  iron 
  ; 
  b 
  was 
  of 
  brass, 
  and 
  e 
  of 
  

   glass, 
  a 
  and 
  the 
  whole 
  system 
  of 
  tubes 
  A, 
  JB 
  and 
  C 
  were 
  filled 
  

   with 
  alcohol, 
  and 
  b, 
  c, 
  d 
  and 
  e 
  up 
  to 
  the 
  2 
  

  

  platinum 
  wire 
  at 
  f 
  with 
  pure 
  mercury. 
  

   The 
  alcohol 
  in 
  the 
  large 
  system 
  of 
  tubes 
  

   expanding 
  and 
  contracting 
  forced 
  the 
  mer- 
  

   cury 
  up 
  and 
  down, 
  making 
  and 
  breaking 
  

   the 
  contact 
  aty. 
  At 
  the 
  joints 
  between 
  a 
  

   and 
  b, 
  b 
  and 
  c, 
  and 
  d 
  and 
  e 
  were 
  rubber 
  

   washers; 
  and 
  screw 
  clamps, 
  not 
  shown 
  in 
  

   the 
  figure, 
  pressed 
  the 
  several 
  parts 
  firmly 
  

   together. 
  

  

  The 
  reason 
  for 
  inserting 
  the 
  small 
  brass 
  

   reservoir 
  b 
  in 
  the 
  portion 
  of 
  the 
  tube 
  con- 
  

   taining 
  the 
  mercury 
  was 
  this. 
  Without 
  

   it 
  we 
  found 
  that 
  the 
  temperature 
  at 
  which 
  

   contact 
  was 
  made 
  and 
  broken 
  at 
  ykept 
  

   gradually 
  rising, 
  indicating 
  a 
  small 
  leakage 
  

   of 
  alcohol. 
  Since 
  the 
  insertion 
  of 
  an 
  

   easily 
  amalgamated 
  metal 
  in 
  part 
  of 
  the 
  

   tubing 
  containing 
  the 
  mercury 
  completely 
  corrected 
  this 
  fault, 
  

   we 
  surmised 
  that 
  the 
  leakage 
  must 
  have 
  taken 
  place 
  along 
  the 
  

   contact 
  surface 
  between 
  the 
  mercury 
  and 
  the 
  iron 
  tubing. 
  No 
  

   appearance 
  of 
  alcohol 
  2Xf 
  was 
  noticed, 
  but 
  it 
  could 
  easily 
  have 
  

   evaporated 
  too 
  rapidly. 
  

  

  The 
  binding 
  posts 
  at 
  g 
  and 
  h 
  were 
  connected 
  to 
  a 
  circuit 
  

   containing 
  a 
  dry 
  cell 
  and 
  a 
  relay. 
  The 
  relay 
  opened 
  and 
  

   closed 
  a 
  second 
  circuit 
  containing 
  an 
  electromagnet, 
  which 
  in 
  

   turn 
  controlled 
  the 
  main 
  heating 
  circuit. 
  

  

  For 
  temperatures 
  only 
  a 
  few 
  degrees 
  above 
  that 
  of 
  the 
  room 
  

   the 
  makes 
  and 
  breaks 
  at 
  f 
  may 
  open 
  and 
  close 
  the 
  heating 
  

   circuit 
  completely 
  ; 
  but 
  for 
  temperatures 
  30° 
  or 
  40° 
  C. 
  above 
  

   that 
  of 
  the 
  room 
  it 
  is 
  better 
  to 
  arrange 
  the 
  circuits 
  so 
  that 
  the 
  

   makes 
  and 
  breaks 
  at 
  /'throw 
  an 
  extra 
  resistance 
  into 
  and 
  out 
  

   of 
  the 
  main 
  circuit. 
  In 
  this 
  case, 
  of 
  course, 
  the 
  larger 
  of 
  the 
  

   two 
  main 
  currents 
  must 
  be 
  sufficient 
  to 
  heat 
  the 
  bath 
  up 
  to 
  a 
  

   higher 
  temperature 
  than 
  the 
  required 
  one, 
  and 
  the 
  smaller 
  

   insufficient 
  to 
  maintain 
  it 
  at 
  that 
  temperature. 
  

  

  