﻿44 
  

  

  Mr. 
  R. 
  F. 
  D'Arcy 
  on 
  the 
  

  

  The 
  dish 
  was 
  connected 
  by 
  means 
  of 
  a 
  wire 
  s 
  with 
  one 
  pair 
  

   of 
  quadrants 
  of 
  a 
  quadrant-electrometer, 
  the 
  other 
  quadrants 
  

   being 
  earthed. 
  The 
  needle 
  had 
  an 
  independent 
  positive 
  

   charge. 
  The 
  following 
  experiments 
  required 
  the 
  instrument 
  

   to 
  be 
  in 
  a 
  comparatively 
  insensitive 
  condition. 
  

  

  The 
  only 
  part 
  of 
  the 
  apparatus 
  of 
  which 
  a 
  detailed 
  descrip- 
  

   tion 
  need 
  be 
  given 
  is 
  the 
  insulating 
  stand. 
  A 
  vertical 
  section 
  

   of 
  this, 
  drawn 
  to 
  scale, 
  is 
  given 
  in 
  fig. 
  2. 
  Here 
  a 
  is 
  a 
  disk 
  

   of 
  varnished 
  wood 
  supported 
  by 
  bb 
  an 
  ebonite 
  rod 
  held 
  in 
  

  

  Fig. 
  2. 
  

  

  J 
  ACTl/AL 
  S/Z£ 
  

  

  position 
  by 
  being 
  cemented 
  with 
  sulphur 
  c 
  to 
  the 
  base 
  board 
  

   d. 
  Let 
  into 
  the 
  sulphur 
  also 
  are 
  the 
  drying-bottles//' 
  (of 
  

   which 
  there 
  are 
  four, 
  all 
  containing 
  sulphuric 
  acid), 
  and 
  the 
  

   tall 
  glass 
  gas-jar 
  <?, 
  which 
  was 
  cleaned 
  so 
  as 
  to 
  have 
  a 
  good 
  

   insulating 
  surface 
  internally 
  when 
  dry, 
  this 
  jar 
  being 
  cemented 
  

   on 
  with 
  melted 
  sulphur. 
  An 
  ebonite 
  disk 
  h 
  was 
  sealed 
  to 
  the 
  

   top 
  of 
  the 
  jar 
  through 
  a 
  hole 
  in 
  the 
  centre 
  of 
  which 
  the 
  

   ebonite 
  rod 
  passed; 
  this 
  hole 
  was 
  about 
  6 
  mm. 
  wider 
  than 
  

  

  