﻿364 
  Mr. 
  N. 
  E. 
  Gilbert 
  : 
  Experiments 
  upon 
  the 
  

  

  The 
  final 
  readings 
  were 
  made 
  on 
  the 
  night 
  of 
  May 
  29, 
  

   1899, 
  when 
  the 
  galvanometer 
  was 
  reasonably 
  steady. 
  The 
  

   switch 
  S 
  was 
  so 
  placed 
  that 
  the 
  currents 
  in 
  the 
  two 
  coils 
  in 
  

   the 
  case 
  B 
  maintained 
  magnetic 
  fields 
  in 
  the 
  same 
  direction 
  

   and 
  the 
  bridge 
  was 
  balanced 
  by 
  means 
  of 
  the 
  shunt 
  R. 
  The 
  

   direction 
  of 
  flow 
  of 
  the 
  current 
  in 
  one 
  of 
  the 
  coils 
  in 
  B 
  was 
  

   then 
  reversed, 
  causing 
  the 
  two 
  fields 
  to 
  oppose 
  each 
  other, 
  

   and 
  the 
  bridge 
  was 
  balanced 
  again. 
  The 
  current 
  was 
  then 
  

   reversed 
  again 
  and 
  the 
  bridge 
  balanced 
  once 
  more. 
  From 
  

   fifteen 
  to 
  thirty 
  seconds 
  were 
  required 
  to 
  balance 
  the 
  bridge 
  

   between 
  readings. 
  Thirty 
  readings 
  were 
  taken 
  in 
  this 
  way, 
  

   the 
  mean 
  of 
  which 
  showed 
  the 
  shunt 
  resistance 
  to 
  be 
  3*4 
  ohms 
  

   less 
  when 
  the 
  magnetic 
  field 
  was 
  maintained 
  in 
  B. 
  The 
  

   shunt 
  was 
  so 
  placed 
  (see 
  fig 
  1) 
  that 
  this 
  indicates 
  a 
  smaller 
  

   resistance, 
  in 
  the 
  coils 
  in 
  B, 
  by 
  one 
  part 
  in 
  1,200,000 
  when 
  

   maintaining 
  a 
  field 
  than 
  when 
  not 
  maintaining 
  a 
  field. 
  

  

  The 
  above 
  result 
  is 
  not 
  in 
  the 
  direction 
  to 
  indicate 
  that 
  any 
  

   energy 
  is 
  used 
  in 
  maintaining 
  the 
  field. 
  The 
  difficulty 
  may 
  

   lie 
  in 
  the 
  fact 
  that 
  the 
  galvanometer, 
  though 
  used 
  at 
  night, 
  

   was 
  unsteady 
  at 
  best, 
  the 
  probable 
  error 
  of 
  the 
  mean 
  being 
  

   1*9 
  ohms 
  ; 
  or 
  it 
  may 
  be 
  due 
  to 
  leakage. 
  The 
  resistance 
  of 
  

   the 
  coils 
  was 
  100 
  ohms, 
  while 
  the 
  insulation 
  resistance 
  was 
  

   11,000,000 
  ohms. 
  If 
  the 
  leakage 
  is 
  symmetrical 
  along 
  the 
  

   doubled 
  wire, 
  it 
  will 
  not 
  affect 
  the 
  galvanometer 
  upon 
  reversing 
  

   the 
  current 
  in 
  one 
  coil, 
  but 
  the 
  assumption 
  that 
  it 
  is 
  sym- 
  

   metrical 
  may 
  not 
  be 
  justified. 
  

  

  Relative 
  motion 
  of 
  JEther 
  and 
  Matter. 
  — 
  Another 
  important 
  

   question 
  to 
  be 
  decided 
  by 
  experiment 
  concerns 
  the 
  relative 
  

   motion 
  of 
  asther 
  and 
  matter. 
  Does 
  the 
  sether 
  immediately 
  

   surrounding 
  a 
  mass 
  of 
  matter 
  move 
  with 
  the 
  matter 
  in 
  its 
  

   excursions 
  through 
  space, 
  or 
  does 
  it 
  allow 
  r 
  the 
  matter 
  to 
  pass 
  

   unopposed 
  ? 
  Experiments 
  upon 
  this 
  subject 
  give 
  discordant 
  

   results. 
  If, 
  as 
  the 
  above 
  experiment 
  seems 
  to 
  show, 
  the 
  aather 
  

   offers 
  no 
  frictional 
  or 
  viscous 
  resistance, 
  we 
  might 
  expect 
  it 
  

   to 
  remain 
  stationary, 
  allowing 
  the 
  free 
  passage 
  of 
  matter 
  

   through 
  it. 
  The 
  phenomenon 
  of 
  aberration 
  and 
  the 
  shift 
  of 
  

   spectrum 
  lines 
  in 
  accordance 
  with 
  Doppler's 
  principle 
  are 
  

   explained 
  on 
  this 
  hypothesis, 
  as 
  well 
  as 
  the 
  fact 
  that 
  no 
  comet 
  

   has 
  yet 
  shown 
  any 
  acceleration 
  due 
  to 
  aathereal 
  resistance. 
  

   The 
  elaborate 
  experiments 
  of 
  Oliver 
  Lodge*, 
  in 
  which 
  he 
  

   passed 
  a 
  beam 
  of 
  light 
  several 
  times 
  around 
  the 
  space 
  between 
  

   two 
  rapidly 
  rotating 
  disks, 
  failed 
  to 
  show 
  any 
  difference 
  in 
  

   the 
  velocity 
  of 
  the 
  beams 
  passing 
  round 
  in 
  opposite 
  directions. 
  

  

  On 
  the 
  other 
  hand, 
  the 
  fact 
  that 
  a 
  vibrating 
  molecule 
  can 
  

  

  * 
  Phil. 
  Trans, 
  vol. 
  clxxxiv. 
  p. 
  727 
  (1893). 
  

  

  