﻿448 
  

  

  Mr, 
  T. 
  Mizuno 
  on 
  the 
  Function 
  of 
  

  

  communicate 
  the 
  results 
  of 
  my 
  investigations 
  on 
  the 
  con- 
  

   denser, 
  which 
  seem 
  to 
  me 
  to 
  throw 
  some 
  new 
  light 
  on 
  its 
  

   action. 
  The 
  object 
  of 
  my 
  investigation 
  was 
  to 
  examine 
  the 
  

   effect 
  which 
  variations 
  of 
  the 
  capacity 
  of 
  the 
  condenser 
  

   inserted 
  in 
  the 
  primary 
  circuit 
  produced 
  upon 
  the 
  maximum 
  

   spark-lengths 
  of 
  the 
  secondary, 
  when 
  the 
  primary 
  current 
  

   was 
  kept 
  constant. 
  

  

  Experiments. 
  

  

  An 
  induction-coil 
  11 
  centim. 
  in 
  diameter, 
  21 
  centim. 
  in 
  

   length, 
  and 
  having 
  a 
  mercury 
  interruptor 
  was 
  used 
  for 
  

   experiment. 
  The 
  condenser 
  of 
  the 
  coil 
  was 
  removed, 
  and 
  an 
  

   adjustable 
  condenser 
  was 
  put 
  in 
  its 
  place. 
  The 
  primary 
  

   circuit 
  was 
  fed 
  by 
  nine 
  accumulators, 
  the 
  strength 
  of 
  the 
  

   current 
  being 
  regulated 
  by 
  means 
  of 
  a 
  rheostat. 
  

  

  The 
  arrangement 
  of 
  the 
  experiment 
  is 
  shown 
  in 
  the 
  annexed 
  

   figure 
  : 
  — 
  ■ 
  

  

  P 
  S 
  

  

  P 
  and 
  S 
  denote 
  the 
  primary 
  and 
  the 
  secondary 
  circuits 
  

   respectively. 
  Q 
  is 
  the 
  mercury 
  interruptor, 
  and 
  the 
  inter- 
  

   ruption 
  was 
  effected 
  by 
  hand. 
  C 
  is 
  the 
  condenser, 
  whose 
  

   capacity 
  could 
  be 
  varied 
  between 
  0*05 
  and 
  1*00 
  microfarad. 
  

  

  The 
  maximum 
  spark-lengths 
  between 
  the 
  terminals 
  of 
  the 
  

   secondary 
  circuit 
  were 
  determined 
  by 
  a 
  point- 
  plate 
  spark 
  

   micrometer 
  R, 
  each 
  measurement 
  being 
  made 
  five 
  times, 
  and 
  

   the 
  primary 
  current 
  was 
  measured 
  by 
  a 
  Lord 
  Kelvin's 
  graded 
  

   current-meter 
  G. 
  

  

  Since 
  the 
  spark-length 
  depends, 
  to 
  a 
  large 
  extent, 
  upon 
  the 
  

   surface 
  conditions, 
  especially 
  on 
  that 
  of 
  the 
  point, 
  the 
  latter 
  

   was 
  each 
  time 
  thoroughly 
  polished 
  with 
  sand-paper. 
  Even 
  

   with 
  this 
  precaution 
  the 
  spark-lengths 
  occasionally 
  showed 
  

   some 
  irregularities. 
  The 
  results 
  of 
  observation 
  are 
  given 
  in 
  

   the 
  following 
  table 
  : 
  — 
  

  

  