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  Duane 
  and 
  Lory 
  — 
  Electrical 
  Thermostat. 
  

  

  bath. 
  The 
  boiler 
  was 
  placed 
  in 
  a 
  large 
  wooden 
  box 
  and 
  packed 
  

   in 
  around 
  the 
  sides 
  with 
  wool. 
  A 
  light 
  wooden 
  frame 
  immersed 
  

   in 
  the 
  water 
  served 
  as 
  a 
  rack 
  to 
  hold 
  the 
  wires 
  conveying 
  the 
  

   current. 
  We 
  encountered 
  considerable 
  difficulty, 
  however, 
  owing 
  

   to 
  the 
  wires 
  becoming 
  very 
  brittle 
  and 
  breaking 
  after 
  a 
  few 
  

   days' 
  use. 
  This 
  was 
  the 
  case 
  with 
  wires 
  of 
  copper, 
  iron 
  and 
  

   German 
  silver. 
  A 
  direct 
  current, 
  too, 
  seemed 
  to 
  produce 
  a 
  

   much 
  greater 
  effect 
  than 
  an 
  alternating 
  one 
  of 
  the 
  same 
  heat- 
  

   ing 
  power. 
  

  

  To 
  obviate 
  this, 
  difficulty 
  we 
  constructed 
  a 
  wooden 
  trough 
  

   (80 
  cm 
  x4:0 
  cm 
  x50 
  em 
  ) 
  and 
  filled 
  it 
  with 
  a 
  weak 
  solution 
  of 
  com- 
  

   mon 
  salt 
  in 
  water. 
  The 
  two 
  ends 
  of 
  the 
  trough 
  were 
  com- 
  

  

  A 
  

  

  B 
  

  

  pletely 
  covered 
  inside 
  with 
  sheets 
  of 
  zinc, 
  that 
  served 
  as 
  

   electrodes 
  by 
  means 
  of 
  which 
  an 
  alternating 
  current 
  from 
  the 
  

   110 
  volt 
  electric 
  light 
  circuit 
  passed 
  through 
  the 
  solution. 
  

   This 
  method 
  of 
  heating 
  proved 
  very 
  satisfactory. 
  

  

  The 
  liquid 
  in 
  the 
  bath 
  was 
  kept 
  in 
  continual 
  and 
  rapid 
  circu- 
  

   lation 
  by 
  means 
  of 
  four 
  stirrers 
  operated 
  by 
  a 
  small 
  water 
  

   motor. 
  

  

  The 
  tubes 
  containing 
  the 
  expanding 
  liquid 
  were 
  of 
  thin 
  brass 
  

   about 
  2"5 
  cm 
  in 
  diameter. 
  They 
  were 
  fastened 
  together 
  by 
  

   means 
  of 
  iron 
  joints 
  in 
  the 
  form 
  of 
  two 
  rectangles 
  (A 
  and 
  B, 
  

   fig. 
  1). 
  The 
  tube 
  C 
  connected 
  the 
  two 
  rectangles 
  together. 
  

  

  