﻿AND 
  BATTERY 
  DISCHARGER, 
  ETC., 
  ETC. 
  367 
  

  

  , 
  JJiv., 
  

  

  rating. 
  Two 
  brass 
  plates, 
  S 
  S, 
  are 
  secured 
  to 
  the 
  pedestal 
  by 
  a 
  screw 
  

   bolt 
  N, 
  which 
  passes 
  through 
  a 
  hole 
  made 
  in 
  each, 
  near 
  one 
  extremity 
  : 
  

   the 
  plates 
  are 
  thus 
  allowed 
  a 
  circular 
  motion 
  about 
  the 
  bolt, 
  so 
  as 
  to 
  be 
  

   set 
  in 
  one 
  straight 
  line, 
  or 
  in 
  any 
  angle 
  with 
  each 
  other. 
  On 
  one 
  of 
  

   the 
  plates 
  near 
  the 
  extremity 
  not 
  secured 
  by 
  the 
  bolt, 
  a 
  brass 
  socket 
  is 
  

   soldered, 
  into 
  which 
  a 
  glass 
  column 
  C 
  is 
  cemented, 
  surmounted 
  by 
  a 
  

   forceps. 
  At 
  the 
  corresponding 
  end 
  of 
  the 
  other 
  plate, 
  there 
  is 
  a 
  brass 
  

   rod 
  R, 
  perpendicular 
  to 
  the 
  plate, 
  and 
  parallel 
  to 
  the 
  glass 
  column. 
  

   This 
  rod 
  is 
  also 
  furnished 
  with 
  forceps. 
  Between 
  these 
  forceps, 
  and 
  

   those 
  at 
  F, 
  supported 
  and 
  insulated 
  by 
  the 
  glass 
  column 
  C, 
  a 
  wire 
  is 
  

   stretched, 
  which 
  may 
  be 
  of 
  various 
  lengths, 
  according 
  to 
  the 
  angle 
  

   which 
  the 
  plates 
  S 
  S 
  make 
  with 
  each 
  other. 
  The 
  pedestal 
  should 
  be 
  

   metallic, 
  or 
  have 
  a 
  metallic 
  plate 
  at 
  bottom, 
  in 
  communication 
  with 
  

   the 
  external 
  coating 
  of 
  the 
  battery. 
  This 
  being 
  accomplished, 
  it 
  is 
  

   only 
  necessary 
  to 
  charge 
  the 
  battery, 
  without 
  subsequently 
  breaking 
  

   the 
  communication 
  between 
  the 
  inner 
  coatings 
  of 
  the 
  jars, 
  and 
  the 
  

   prime 
  conductor, 
  by 
  which 
  the 
  charge 
  is 
  conveyed. 
  In 
  that 
  case, 
  

   touching 
  the 
  conductor 
  is 
  equivalent 
  to 
  a 
  contact 
  with 
  the 
  inner 
  coat- 
  

   ings 
  of 
  the 
  jars, 
  so 
  far 
  as 
  electrical 
  results 
  are 
  concerned. 
  Hence, 
  by 
  

   causing 
  one 
  of 
  the 
  knobs 
  of 
  the 
  discharger 
  D, 
  with 
  glass 
  handles, 
  to 
  be 
  

   in 
  contact 
  with 
  the 
  insulated 
  forceps 
  F, 
  and 
  then 
  approximating 
  the 
  

   other 
  knob 
  to 
  the 
  prime 
  conductor 
  B, 
  the 
  charge 
  of 
  the 
  battery 
  will 
  

   pass 
  through 
  the 
  wire 
  W, 
  as 
  it 
  cannot 
  descend 
  by 
  the 
  glass 
  column, 
  

   nor 
  reach 
  the 
  operator 
  through 
  the 
  glass 
  handles. 
  These 
  should 
  be 
  

   longer 
  than 
  represented 
  in 
  the 
  cut. 
  

  

  LONG 
  ZIGZAG 
  OR 
  ERRATIC 
  SPARK, 
  CONTRASTED 
  WITH 
  THE 
  SHORT 
  

  

  STRAIGHT 
  SPARK. 
  

  

  "The 
  cause 
  of 
  this 
  difference 
  between 
  the 
  lengths 
  of 
  the 
  two 
  electricities, 
  we 
  have 
  no 
  

   means 
  of 
  explaining." 
  — 
  Tliompsori's 
  work 
  on 
  Heat 
  and 
  Electricity. 
  

  

  The 
  object 
  of 
  the 
  engraving 
  on 
  the 
  following 
  page 
  is 
  to 
  represent 
  

   the 
  different 
  forms 
  and 
  lengths 
  of 
  the 
  electric 
  spark, 
  which 
  take 
  place 
  

   between 
  a 
  large 
  and 
  a 
  small 
  ball, 
  accordingly 
  as 
  they 
  are 
  made 
  nega- 
  

   tive 
  or 
  positive. 
  The 
  long 
  and 
  zigzag, 
  or 
  erratic 
  spark 
  A 
  takes 
  place 
  

   between 
  a 
  small 
  ball 
  attached 
  to 
  the 
  positive 
  pole, 
  and 
  a 
  large 
  one 
  

   associated 
  with 
  the 
  negative 
  pole. 
  The 
  short 
  straight 
  spark 
  B 
  is 
  eli- 
  

  

  