﻿34 
  Dr. 
  A. 
  C. 
  Crehore 
  on 
  the 
  Formation 
  of 
  the 
  

  

  The 
  purpose 
  in 
  view 
  was 
  to 
  produce 
  if 
  possible 
  a 
  set 
  

   of 
  figures 
  exactly 
  similar 
  to 
  those 
  in 
  the 
  calculated 
  Table 
  I., 
  

   and 
  the 
  means 
  by 
  which 
  this 
  was 
  accomplished 
  were 
  con- 
  

   sidered 
  of 
  secondary 
  importance. 
  Exact 
  measurements 
  may 
  

   be 
  made 
  afterwards. 
  This 
  is 
  proceeding 
  upon 
  the 
  principle 
  

   that 
  if 
  the 
  proper 
  series 
  of 
  figures 
  were 
  obtained, 
  the 
  proba- 
  

   bility 
  is 
  that 
  the 
  laws 
  of 
  force 
  assumed 
  when 
  those 
  figures 
  

   were 
  calculated 
  would 
  be 
  fairly 
  closely 
  approximated, 
  and 
  

   the 
  results 
  seem 
  to 
  show 
  that 
  this 
  is 
  correct. 
  

  

  With 
  this 
  source 
  of 
  power 
  it 
  is 
  not 
  possible 
  to 
  avoid 
  

   a 
  continual 
  vibration 
  of 
  the 
  supporting 
  wires, 
  and 
  this 
  is 
  so 
  

   great 
  that 
  the 
  figures 
  cannot 
  be 
  obtained 
  when 
  the 
  sus- 
  

   pension 
  is 
  in 
  free 
  air. 
  The 
  spheres 
  only 
  were 
  immersed 
  in 
  

   a 
  bath 
  of 
  oil. 
  There 
  is 
  a 
  two-fold 
  advantage 
  in 
  this 
  : 
  first, 
  

   the 
  spheres 
  come 
  to 
  their 
  equilibrium 
  positions 
  without 
  

   oscillation 
  and 
  remain 
  at 
  rest 
  in 
  these 
  positions; 
  and 
  second, 
  

   by 
  using 
  the 
  proper 
  oil 
  the 
  specific 
  inductive 
  capacity 
  of 
  

   the 
  medium 
  is 
  increased 
  several 
  fold, 
  and 
  the 
  charge 
  on 
  the 
  

   spheres 
  increased 
  in 
  greater 
  proportion 
  than 
  that 
  upon 
  the 
  

   supporting 
  wires 
  which 
  are 
  in 
  the 
  air. 
  This 
  makes 
  the 
  effect 
  

   of 
  the 
  supporting 
  wires 
  more 
  negligible, 
  and 
  approximates 
  

   nearer 
  to 
  the 
  desired 
  condition. 
  In 
  the 
  tables 
  the 
  specific 
  

   inductive 
  capacity 
  of 
  castor-oil 
  is 
  given 
  as 
  4*7, 
  and 
  this 
  was 
  

   used 
  partly 
  because 
  of 
  its 
  large 
  value, 
  and 
  also 
  because 
  it 
  is 
  

   viscous 
  at 
  ordinary 
  temperatures 
  and 
  quite 
  transparent, 
  

   which 
  is 
  better 
  for 
  securing 
  photographs. 
  The 
  temperature 
  

   was 
  controlled 
  by 
  a 
  spirit-lamp 
  under 
  the 
  oil-bath, 
  and 
  the 
  

   viscosity 
  of 
  the 
  oil 
  kept 
  at 
  any 
  desired 
  point. 
  At 
  21° 
  C. 
  it 
  

   is 
  about 
  right. 
  

  

  A 
  series 
  of 
  photographs 
  secured 
  with 
  the 
  0*794 
  cm. 
  steel 
  

   balls 
  suspended 
  in 
  castor-oil 
  is 
  shown 
  in 
  fig. 
  4 
  (PI. 
  II.). 
  The 
  

   figures 
  are 
  seen 
  to 
  resemble 
  those 
  of 
  the 
  first 
  set, 
  fig. 
  3, 
  in 
  

   that 
  the 
  rings 
  are 
  formed 
  in 
  the 
  centre 
  for 
  a 
  smaller 
  number 
  

   of 
  spheres 
  than 
  either 
  those 
  with 
  magnets 
  or 
  the 
  calculated 
  

   table. 
  

  

  The 
  next 
  process 
  was 
  to 
  control 
  the 
  figures, 
  which 
  was 
  

   accomplished 
  by 
  surrounding 
  the 
  spheres 
  and 
  suspension 
  

   wires 
  by 
  conductors 
  connected 
  to 
  the 
  opposite 
  terminal 
  of 
  

   the 
  power 
  from 
  the 
  spheres. 
  The 
  final 
  arrangement 
  was 
  

   to 
  surround 
  the 
  whole 
  system 
  by 
  an 
  iron 
  wire 
  screen 
  about 
  

   30*5 
  cm. 
  in 
  diameter 
  and 
  53 
  cm. 
  high 
  resting 
  upon 
  a 
  flat 
  

   steel 
  plate, 
  the 
  distance 
  of 
  which 
  below 
  the 
  spheres 
  was 
  

   adjustable. 
  By 
  this 
  means 
  it 
  was 
  found 
  that 
  the 
  exact 
  

   figures 
  calculated 
  in 
  Table 
  I. 
  could 
  be 
  reproduced. 
  The 
  

   exact 
  distribution 
  of 
  the 
  charge 
  has 
  not 
  as 
  yet 
  been 
  measured. 
  

   When 
  there 
  is 
  only 
  a 
  single 
  ring 
  of 
  spheres, 
  it 
  may 
  be 
  said 
  

  

  