﻿434 
  Mr. 
  0. 
  A. 
  Chant 
  : 
  An 
  Experimental 
  Investigation 
  

  

  tried, 
  but 
  they 
  were 
  entirely 
  useless, 
  the 
  reflected 
  waves 
  

   apparently 
  destroying 
  completely 
  the 
  direct 
  waves 
  *. 
  

  

  3. 
  The 
  Receiver. 
  

  

  As 
  a 
  receiver 
  I 
  used 
  the 
  magnetic 
  detector 
  devised 
  by 
  

   Rutherford 
  f 
  and 
  described 
  by 
  him 
  in 
  1896. 
  A 
  few 
  inches 
  

   of 
  iron 
  wire 
  0*14 
  mm. 
  in 
  diameter 
  were 
  dipped 
  in 
  melted 
  

   paraffin 
  and, 
  after 
  cooling, 
  the 
  wire 
  was 
  cut 
  into 
  about 
  20 
  

   pieces. 
  Holding 
  these 
  together, 
  about 
  90 
  turns 
  o£ 
  fine 
  

   (No. 
  40) 
  insulated 
  copper 
  wire 
  were 
  wound 
  upon 
  about 
  

   1 
  cm. 
  of 
  their 
  length 
  ; 
  and 
  after 
  the 
  protruding 
  ends 
  of 
  the 
  

   iron 
  wire 
  had 
  been 
  cut 
  off 
  and 
  the 
  fine 
  wire 
  had 
  

   been 
  soldered 
  to 
  heavier 
  copper 
  wires, 
  the 
  helix 
  Fig. 
  5. 
  

   with 
  its 
  iron 
  core 
  was 
  mounted 
  in 
  the 
  end 
  of 
  

   a 
  small 
  glass 
  tube, 
  the 
  connecting 
  wires 
  being- 
  

   drawn 
  through 
  the 
  other 
  end 
  of 
  the 
  glass 
  tube. 
  

   The 
  helix 
  was 
  kept 
  in 
  place 
  by 
  simply 
  dipping 
  

   the 
  tube 
  in 
  melted 
  paraffin 
  and 
  then 
  allowing 
  

   it 
  to 
  cool. 
  The 
  entire 
  arrangement 
  is 
  shown 
  

   (half 
  size) 
  in 
  fig. 
  5. 
  The 
  helix 
  is 
  seen 
  at 
  H 
  and 
  

   the 
  ends 
  of 
  the 
  wire 
  are 
  shown 
  at 
  e, 
  e, 
  curved 
  as 
  

   they 
  were 
  used. 
  

  

  On 
  a 
  wooden 
  rod 
  about 
  65 
  cms. 
  long 
  tw 
  r 
  o 
  wires 
  (fig. 
  6) 
  

  

  Fig. 
  6. 
  

  

  *=t 
  

  

  were 
  fastened 
  with 
  soft 
  wax, 
  their 
  near-together 
  ends 
  termi- 
  

   nating 
  in 
  small 
  mercury 
  cups. 
  The 
  bar 
  was 
  cut 
  out 
  at 
  its 
  

   central 
  portion 
  so 
  that 
  the 
  detector 
  could 
  hang 
  vertically 
  

   with 
  its 
  ends 
  in 
  the 
  mercury 
  cups. 
  Thus 
  the 
  wings 
  became 
  

   electrically 
  a 
  portion 
  of 
  the 
  wire 
  of 
  the 
  helix. 
  The 
  wooden 
  

   bar 
  was 
  mounted 
  in 
  a 
  parabolic 
  reflector 
  so 
  that 
  the 
  wire 
  lay 
  

   along 
  a 
  focal 
  line 
  (fig. 
  7). 
  

  

  The 
  method 
  of 
  using 
  was 
  as 
  follows. 
  The 
  iron 
  of 
  the 
  

   detector 
  was 
  first 
  magnetized 
  to 
  saturation 
  by 
  being 
  thrust 
  

   into 
  a 
  helix 
  in 
  which 
  a 
  current 
  was 
  made 
  to 
  circulate. 
  The 
  

   detector 
  was 
  then 
  hung 
  so 
  as 
  to 
  connect 
  with 
  its 
  wings,, 
  and 
  

   on 
  placing 
  it 
  in 
  the 
  field 
  of 
  an 
  electric 
  oscillator, 
  the 
  surgings 
  

  

  * 
  I 
  had 
  forgotten 
  Hertz's 
  experience. 
  ' 
  See 
  Electric 
  Waves/ 
  pp. 
  ] 
  72, 
  175. 
  

   t 
  Phil. 
  Trans. 
  A 
  1897, 
  vol. 
  clxxxix. 
  pp. 
  1-24. 
  

  

  