﻿Relation* 
  between 
  ^Ether, 
  Matter, 
  and 
  Electricity. 
  365 
  

  

  set 
  up 
  vibrations 
  in 
  the 
  aether 
  may 
  indicate 
  that 
  there 
  is 
  some 
  

   sort 
  of 
  frictional 
  connexion 
  between 
  the 
  molecule 
  and 
  the 
  

   aether. 
  Fizeau 
  * 
  has 
  shown 
  that 
  when 
  two 
  beams 
  of 
  light, 
  

   passing 
  in 
  opposite 
  directions 
  through 
  a 
  tube 
  of 
  water, 
  are 
  

   made 
  to 
  interfere, 
  the 
  fringes 
  are 
  displaced 
  when 
  the 
  water 
  

   is 
  set 
  in 
  motion, 
  indicating 
  that 
  the 
  aether 
  is 
  carried 
  with 
  the 
  

   water. 
  His 
  measurements 
  indicated 
  that 
  the 
  water 
  moves 
  a 
  

   little 
  faster 
  than 
  the 
  aether. 
  This 
  experiment 
  has 
  been 
  repeated 
  

   and 
  the 
  results 
  confirmed 
  by 
  Michelson 
  and 
  Morley 
  f 
  . 
  Again, 
  

   Michelson 
  and 
  Morley 
  J 
  have 
  made 
  an 
  elaborate 
  series 
  of 
  

   experiments 
  with 
  their 
  interferometer, 
  and 
  have 
  been 
  able 
  to 
  

   detect 
  no 
  displacement 
  of 
  the 
  fringes 
  as 
  the 
  instrument 
  was 
  

   rotated 
  through 
  different 
  angles 
  with 
  respect 
  to 
  the 
  direction 
  

   of 
  motion 
  of 
  the 
  earth, 
  thus 
  seeming 
  to 
  show 
  that 
  the 
  aether 
  

   moves 
  with 
  the 
  earth. 
  Sutherland 
  § 
  tried 
  to 
  explain 
  this 
  by 
  

   showing 
  that 
  the 
  displacement, 
  while 
  perfectly 
  possible, 
  would 
  

   be 
  too 
  small 
  to 
  be 
  detected 
  by 
  the 
  adjustment 
  of 
  their 
  

   experiment; 
  but 
  Lodge 
  || 
  dismisses 
  this 
  explanation 
  and 
  sug- 
  

   gests, 
  with 
  Fitz 
  Gerald 
  1[ 
  and 
  Lorentz 
  **, 
  that 
  the 
  molecules 
  of 
  

   the 
  instrument 
  and 
  of 
  the 
  heavy 
  stone 
  slab 
  on 
  which 
  it 
  rests 
  

   may 
  bear 
  such 
  a 
  relation 
  to 
  the 
  aether 
  that 
  they 
  are 
  compressed 
  

   along 
  the 
  line 
  of 
  motion 
  and 
  so 
  distort 
  the 
  instrument 
  just 
  

   enough 
  to 
  balance 
  the 
  effect 
  of 
  the 
  relative 
  motion. 
  Whether 
  

   or 
  not 
  this 
  explanation 
  is 
  valid, 
  it 
  remains 
  for 
  future 
  experi- 
  

   ments 
  to 
  decide. 
  

  

  Another 
  method 
  by 
  which 
  this 
  problem 
  may 
  be 
  attacked 
  is 
  

   to 
  study 
  the 
  nature 
  of 
  electricity 
  and 
  its 
  relation 
  to 
  matter- 
  

   Maxwell 
  tf 
  made 
  two 
  interesting 
  experiments 
  along 
  this 
  line. 
  

   One 
  of 
  these, 
  in 
  which 
  he 
  showed 
  that 
  a 
  coil 
  of 
  wire, 
  carrying 
  

   a 
  current, 
  had 
  no 
  angular 
  momentum 
  due 
  to 
  the 
  current, 
  has 
  

   already 
  been 
  mentioned. 
  In 
  the 
  other, 
  he 
  showed 
  that 
  

   electricity 
  has 
  no 
  linear 
  momentum, 
  since 
  a 
  delicately 
  sus- 
  

   pended 
  coil 
  showed 
  no 
  tendency 
  to 
  rotate 
  in 
  its 
  own 
  plane 
  

   when 
  a 
  current 
  was 
  started 
  or 
  stopped 
  in 
  it. 
  It 
  was 
  while 
  

   discussing 
  these 
  experiments 
  that 
  Professor 
  Rowland 
  suggested 
  

   the 
  experiment 
  which 
  has 
  since 
  been 
  carried 
  out. 
  The 
  

   experiment 
  consisted 
  in 
  trying 
  to 
  detect 
  a 
  current 
  generated 
  

   in 
  a 
  wire 
  wound 
  on 
  the 
  periphery 
  of 
  a 
  wheel 
  in 
  such 
  a 
  way 
  

   that 
  it 
  would 
  move 
  in 
  the 
  direction 
  of 
  its 
  length 
  when 
  the 
  

  

  * 
  Ann. 
  de 
  Chimie 
  et 
  Physique, 
  tome 
  lvii. 
  p. 
  385 
  (1859). 
  

  

  t 
  Am. 
  Journ. 
  of 
  Sc. 
  (3) 
  vol. 
  xxxi. 
  p. 
  377 
  (1886). 
  

  

  % 
  Phil. 
  Mag. 
  xxiv. 
  p. 
  449 
  (1887); 
  Am. 
  Journ. 
  of 
  Sc. 
  (3) 
  p. 
  475 
  (1897). 
  

  

  § 
  Phil. 
  Mag. 
  xlv. 
  p. 
  23 
  (1898). 
  

  

  || 
  Phil. 
  Mag. 
  xlvi. 
  p. 
  343 
  (1898). 
  

  

  *] 
  Public 
  Lectures 
  in 
  Trinity 
  College, 
  Dublin. 
  

  

  ** 
  Versuch 
  einer 
  Thcorie 
  (lev 
  Electrkchen 
  Korpern. 
  

  

  ft 
  Elec. 
  and 
  Mag. 
  vol. 
  ii. 
  arts. 
  574, 
  575. 
  

  

  