﻿the 
  Source 
  of 
  the 
  x-Rays. 
  189 
  

  

  was 
  exhausted 
  to 
  a 
  very 
  high 
  degree, 
  the 
  mirror 
  formed 
  a 
  

   bright 
  fluorescent 
  spot 
  on 
  the 
  bulb, 
  the 
  position 
  of 
  which 
  

   could 
  be 
  readily 
  changed 
  by 
  means 
  of 
  a 
  magnet. 
  When 
  the 
  

   exhaustion 
  was 
  carried 
  to 
  a 
  very 
  high 
  degree, 
  reversing 
  the 
  

   current 
  from 
  a 
  Ruhmkorf 
  coil 
  through 
  the 
  tube 
  caused 
  no 
  

   marked 
  difference 
  in 
  the 
  appearances 
  in 
  the 
  tube 
  ; 
  at 
  a 
  lower 
  

   degree, 
  however, 
  a 
  marked 
  difference 
  resulted. 
  With 
  the 
  

   employment 
  of 
  a 
  powerful 
  Ruhmkorf 
  coil 
  giving 
  sparks 
  of 
  at 
  

   least 
  8 
  inches 
  cc-rays 
  could 
  be 
  detected 
  in 
  this 
  tube 
  ; 
  and 
  when 
  

   the 
  tube 
  was 
  connected 
  to 
  the 
  Plante 
  machine, 
  the 
  #-rays 
  

   gave 
  strong 
  effects 
  in 
  the 
  fluoroscope. 
  

  

  In 
  order 
  to 
  test 
  the 
  question 
  whether 
  the 
  so-called 
  cathode 
  

   rays 
  and 
  the 
  ^-rays 
  are 
  generated 
  primarily 
  only 
  at 
  the 
  

   cathode, 
  a 
  very 
  large 
  resistance 
  of 
  distilled 
  water 
  was 
  inter- 
  

   posed 
  in 
  the 
  circuit 
  with 
  the 
  continuous 
  wire 
  tube 
  (fig. 
  9), 
  in 
  

   order 
  to 
  damp 
  any 
  oscillations 
  which 
  might 
  arise. 
  The 
  

   circuit 
  thus 
  consisted 
  of 
  the 
  tube, 
  the 
  water-resistance, 
  a 
  

   spark-gap, 
  and 
  the 
  secondary 
  coil 
  of 
  a 
  large 
  Ruhmkorf. 
  The 
  

   tube 
  was 
  connected 
  at 
  first 
  permanently 
  to 
  the 
  air-pump. 
  As 
  

   the 
  exhaustion 
  advanced 
  a 
  beam 
  of 
  rays 
  proceeded 
  from 
  the 
  

   mirror 
  on 
  the 
  continuous 
  conductor, 
  which 
  was 
  focussed 
  on 
  

   the 
  wall 
  of 
  the 
  tube. 
  This 
  beam 
  was 
  more 
  brilliant 
  and 
  pro- 
  

   duced 
  a 
  stronger 
  fluorescence 
  on 
  the 
  tube 
  when 
  the 
  wire 
  

   was 
  negative 
  than 
  when 
  it 
  was 
  positive. 
  At 
  a 
  higher 
  stage 
  of 
  

   the 
  vacuum, 
  however, 
  very 
  little, 
  if 
  any, 
  difference 
  could 
  be 
  

   detected 
  in 
  the 
  appearance 
  of 
  the 
  tube, 
  and 
  #-rays 
  could 
  be 
  

   detected 
  outside 
  the 
  tube 
  opposite 
  the 
  fluorescent 
  spot 
  caused 
  

   by 
  the 
  mirror. 
  That 
  is, 
  the 
  #-rays 
  were 
  given 
  off 
  both 
  when 
  

   the 
  wire 
  constituted 
  the 
  cathode 
  of 
  the 
  circuit 
  and 
  also 
  when 
  

   it 
  formed 
  the 
  anode. 
  

  

  It 
  seems, 
  therefore, 
  that 
  the 
  term 
  cathode-rays 
  is 
  not 
  

   a 
  general 
  one. 
  It 
  would 
  seem 
  that 
  electric 
  rays 
  might 
  

   be 
  a 
  more 
  comprehensive 
  one 
  for 
  both 
  cathode-rays 
  and 
  

   #-rays. 
  

  

  Furthermore, 
  the 
  phenomenon 
  of 
  electrostatic 
  induction 
  

   plays 
  an 
  important 
  part 
  in 
  the 
  phenomena 
  of 
  the 
  so-called 
  

   #-rays. 
  When 
  the 
  tube 
  represented 
  in 
  fig. 
  9 
  had 
  reached 
  a 
  

   certain 
  stage 
  of 
  exhaustion, 
  a 
  bit 
  of 
  tinfoil 
  connected 
  to 
  a 
  zinc 
  

   plate 
  20 
  x 
  25 
  cm. 
  and 
  1 
  mm. 
  thick 
  was 
  stuck 
  upon 
  the 
  

   outside 
  of 
  the 
  tube 
  where 
  the 
  mirror 
  formed 
  the 
  fluorescent 
  

   spot. 
  This 
  zinc 
  plate 
  was 
  carefully 
  insulated 
  from 
  the 
  ground. 
  

   It 
  was 
  seen 
  that 
  a 
  bundle 
  of 
  rays 
  was 
  reflected 
  by 
  the 
  tinfoil 
  

   to 
  the 
  opposite 
  wall 
  of 
  the 
  tube, 
  throwing 
  a 
  well-defined 
  

   shadow 
  of 
  the 
  mirror 
  and 
  the 
  continuous 
  conductor 
  on 
  this 
  

   wall. 
  The 
  direction 
  of 
  this 
  shadow 
  could 
  be 
  changed 
  at 
  will 
  

   by 
  changing 
  the 
  position 
  of 
  the 
  tinfoil. 
  This 
  phenomenon 
  

  

  Phil. 
  Mag. 
  8. 
  5. 
  Vol. 
  45. 
  No. 
  273. 
  Feb. 
  1898. 
  P 
  

  

  