﻿A. 
  G. 
  Webster 
  — 
  Rapid 
  Break 
  for 
  large 
  Currents. 
  385 
  

  

  striction 
  N, 
  it 
  is 
  suddenly 
  jerked 
  up 
  over 
  into 
  A, 
  the 
  level 
  in 
  

   S 
  rises, 
  and 
  the 
  quantity 
  corresponding 
  to 
  that 
  which 
  has 
  been 
  

   raised 
  runs 
  over 
  into 
  the 
  funnel. 
  The 
  mercury 
  in 
  Y 
  has 
  in 
  

   the 
  mean 
  time 
  run 
  down 
  into 
  K, 
  and 
  the 
  process 
  is 
  repeated. 
  

   The 
  mercury 
  in 
  the 
  funnel 
  runs 
  down 
  through 
  the 
  jet 
  J, 
  

   through 
  the 
  tube 
  B 
  full 
  of 
  water, 
  runs 
  out 
  at 
  the 
  bottom 
  

   through 
  the 
  cock 
  D, 
  and 
  through 
  a 
  rubber 
  tube 
  descends 
  to 
  

   the 
  cup 
  K. 
  The 
  current 
  is 
  introduced 
  by 
  a 
  platinum 
  wire 
  

   sealed 
  into 
  the 
  glass 
  at 
  F, 
  and 
  goes 
  out 
  at 
  the 
  wire 
  carried 
  by 
  

   the 
  fork 
  F, 
  and 
  dipping 
  into 
  the 
  mercury 
  through 
  the 
  short 
  

   standing-tube 
  T. 
  Water 
  is 
  introduced 
  at 
  W 
  around 
  the 
  jet, 
  

   and 
  flows 
  out 
  at 
  E. 
  The 
  tube 
  is 
  kept 
  full 
  of 
  water, 
  so 
  that 
  the 
  

   jet 
  is 
  kept 
  cool 
  ; 
  the 
  jet 
  presents 
  a 
  continually 
  fresh 
  surface 
  of 
  

   mercury, 
  the 
  mercury 
  is 
  washed 
  in 
  the 
  flowing 
  water, 
  and 
  

   comes 
  out 
  perfectly 
  clean. 
  The 
  oxide 
  goes 
  off 
  in 
  the 
  waste 
  

   water 
  at 
  E. 
  The 
  surface 
  of 
  the 
  mercury 
  is 
  kept 
  just 
  below 
  

   the 
  tube 
  B, 
  so 
  that 
  no 
  water 
  goes 
  over 
  into 
  the 
  elevator. 
  The 
  

   cock 
  D 
  is 
  for 
  the 
  purpose 
  of 
  keeping 
  the 
  mercury 
  from 
  all 
  

   running 
  down 
  into 
  the 
  cups 
  K 
  on 
  stopping 
  the 
  action 
  of 
  the 
  

   apparatus, 
  and 
  C 
  is 
  to 
  prevent 
  water 
  from 
  the 
  pump 
  getting 
  

   into 
  A 
  on 
  stopping 
  the 
  aspirator. 
  

  

  The 
  apparatus 
  thus 
  described 
  was 
  very 
  satisfactory, 
  a 
  test 
  

   made 
  of 
  its 
  automatic 
  nature 
  having 
  shown 
  that 
  a 
  current 
  of 
  

   twelve 
  mean 
  amperes 
  was 
  carried 
  for 
  an 
  hour 
  without 
  any 
  

   adjustment 
  of 
  the 
  apparatus. 
  For 
  longer 
  periods 
  it 
  would 
  be 
  

   necessary 
  to 
  occasionally 
  pour 
  in 
  a 
  little 
  mercury 
  to 
  replace 
  

   that 
  lost 
  by 
  oxidation, 
  much 
  of 
  which 
  may 
  be 
  recovered 
  by 
  

   running 
  the 
  waste 
  water 
  through 
  a 
  pail 
  in 
  which 
  it 
  may 
  settle. 
  

   The 
  above 
  arrangement 
  seeming 
  rather 
  unnecessarily 
  compli- 
  

   cated, 
  it 
  occurred 
  to 
  me 
  to 
  try 
  to 
  raise 
  the 
  mercury 
  directly 
  by 
  

   water 
  instead 
  of 
  air 
  pressure. 
  To 
  this 
  end 
  a 
  jet 
  of 
  water 
  was 
  

   introduced 
  into 
  a 
  tube 
  containing 
  the 
  mercury 
  to 
  be 
  raised, 
  

   somewhat 
  in 
  the 
  manner 
  of 
  the 
  Giffard 
  injector. 
  This 
  was 
  

   successful, 
  but 
  the 
  mercury 
  was 
  carried 
  up 
  in 
  a 
  multitude 
  of 
  

   fine 
  globules, 
  which 
  sometimes 
  made 
  the 
  stream 
  discontinuous. 
  

   The 
  arrangement 
  was 
  finally 
  simplified 
  by 
  my 
  assistant, 
  Mr. 
  A. 
  

   F. 
  "Wills, 
  into 
  a 
  simple 
  Y-tube, 
  and 
  the 
  apparatus 
  as 
  now 
  used 
  

   is 
  shown 
  in 
  fig. 
  2. 
  The 
  water 
  is 
  introduced 
  at 
  W 
  into 
  one 
  

   arm 
  of 
  the 
  tube 
  Y, 
  into 
  which 
  the 
  mercury 
  enters 
  through 
  the 
  

   other 
  branch 
  from 
  R. 
  The 
  mercury 
  is 
  carried 
  to 
  the 
  right 
  and 
  

   upwards, 
  and 
  is 
  thrown 
  into 
  the 
  supply 
  tube 
  A 
  in 
  quantities 
  of 
  

   about 
  a 
  tea-spoonful 
  at 
  a 
  time. 
  The 
  water 
  escapes 
  at 
  the 
  top 
  

   of 
  A 
  and 
  descending 
  through 
  the 
  rubber 
  tube 
  S 
  enters 
  around 
  

   the 
  jet 
  and 
  keeps 
  the 
  break 
  cool. 
  The 
  waste 
  water 
  rises 
  

   through 
  the 
  wide 
  tube 
  U, 
  so 
  that 
  any 
  mercury 
  that 
  might 
  be 
  

   carried 
  over 
  settles 
  and 
  falls 
  back. 
  The 
  water 
  escapes 
  through 
  

   the 
  siphon 
  E, 
  which 
  should 
  have 
  a 
  pinch-cock 
  at 
  the 
  end 
  to 
  

  

  