﻿the 
  Cathodic 
  Rays 
  and 
  those 
  of 
  Rontgen. 
  169 
  

  

  This 
  last 
  fact 
  would 
  prove 
  in 
  harmony 
  with 
  the 
  hypothesis 
  

   that 
  the 
  photographic 
  action 
  is 
  due 
  to 
  the 
  cathodic 
  rays 
  them- 
  

   selves 
  forced 
  back 
  by 
  the 
  obstacle 
  or 
  piercing 
  through 
  it. 
  

  

  And 
  next, 
  what 
  could 
  not 
  easily 
  be 
  foreseen, 
  is 
  the 
  other 
  

   conclusion 
  suggested 
  by 
  these 
  experiments, 
  namely, 
  that 
  the 
  

   action 
  of 
  the 
  surface 
  facing 
  the 
  cathode 
  is 
  the 
  more 
  feeble 
  the 
  

   less 
  the 
  thickness 
  of 
  the 
  sheet. 
  It 
  would 
  be 
  difficult 
  to 
  place 
  

   this 
  result 
  in 
  harmony 
  with 
  the 
  hypothesis 
  that 
  the 
  Rontgen 
  

   rays 
  emanating 
  from 
  any 
  substance 
  whatever 
  are 
  generated 
  

   by 
  the 
  cathodic 
  rays 
  which 
  strike 
  that 
  same 
  substance. 
  

  

  10th 
  Experiment. 
  — 
  Two 
  bulbs 
  of 
  equal 
  size 
  were 
  placed 
  

   simultaneously 
  in 
  communication 
  with 
  the 
  air-pump, 
  each 
  

   bulb 
  containing 
  the 
  platinum 
  reflector, 
  and 
  also 
  several 
  

   photographic 
  cylinders 
  disposed 
  as 
  in 
  the 
  1st 
  experiment. 
  

  

  One 
  of 
  these 
  reflectors 
  was, 
  however, 
  surrounded 
  by 
  a 
  

   spherical 
  covering 
  of 
  thin 
  black 
  wove 
  paper 
  of 
  the 
  thinness 
  

   of 
  jf 
  ^ 
  of 
  a 
  millimetre. 
  This 
  covering 
  had 
  a 
  small 
  aperture 
  

   in 
  front 
  of 
  the 
  cathode, 
  through 
  which 
  the 
  small 
  pencil 
  of 
  

   cathodic 
  rays 
  penetrated 
  so 
  as 
  to 
  strike 
  direct 
  on 
  the 
  reflector. 
  

  

  The 
  results 
  obtained 
  with 
  both 
  bulbs 
  were 
  identical, 
  with, 
  

   perhaps, 
  a 
  very 
  slight 
  difference 
  in 
  the 
  intensity 
  of 
  the 
  

   impression. 
  Besides 
  which, 
  in 
  the 
  bulb 
  with 
  the 
  spherical 
  

   covering 
  of 
  black 
  thin 
  wove-paper 
  the 
  fluorescence 
  on 
  the 
  

   inner 
  side 
  of 
  the 
  tube 
  was 
  not 
  altered 
  in 
  its 
  distribution 
  nor 
  

   sensibly 
  so 
  in 
  its 
  intensity 
  ; 
  similarly, 
  the 
  shadow 
  projected 
  

   by 
  the 
  reflector 
  on 
  the 
  aforesaid 
  inner 
  side 
  of 
  the 
  tube 
  remained 
  

   unaltered. 
  

  

  Therefore 
  an 
  object 
  surrounding 
  the 
  reflector 
  does 
  not 
  in 
  

   the 
  least 
  way 
  cause 
  any 
  deviation 
  in 
  the 
  action 
  which 
  may 
  be 
  

   obtained 
  within 
  the 
  tube 
  through 
  the 
  effect 
  of 
  the 
  cathodic 
  

   rays 
  reflected 
  by 
  the 
  reflector 
  itself. 
  

  

  11th 
  Experiment.-— 
  Two 
  bulbs 
  were 
  used 
  in 
  this 
  experi- 
  

   ment 
  prepared 
  in 
  the 
  same 
  way 
  as 
  in 
  the 
  first, 
  both 
  having 
  a 
  

   reflector 
  of 
  aluminium 
  of 
  from 
  three 
  to 
  four 
  thousandth 
  parts 
  of 
  

   a 
  millimetre 
  in 
  thickness. 
  To 
  one 
  of 
  these 
  an 
  electromagnet 
  

   was 
  applied 
  behind 
  the 
  reflector 
  in 
  such 
  a 
  way 
  that 
  the 
  lumi- 
  

   nous 
  mark, 
  which 
  was 
  visible 
  in 
  the 
  direction 
  of 
  the 
  incidental 
  

   cathodic 
  pencil, 
  should 
  strongly 
  shift 
  its 
  position. 
  

  

  In 
  the 
  photographic 
  cylinders 
  placed 
  behind 
  the 
  two 
  reflectors, 
  

   impressions 
  were 
  obtained 
  of 
  very 
  nearly 
  the 
  same 
  intensity. 
  

   i 
  I 
  then 
  placed, 
  in 
  the 
  next 
  experiment, 
  two 
  more 
  photo- 
  

   graphic 
  cylinders 
  respectively 
  behind 
  the 
  two 
  small 
  reflectors, 
  

   but 
  in 
  a 
  lateral 
  position. 
  So 
  soon 
  as 
  the 
  first 
  bulb 
  was 
  excited 
  

   I 
  rapidly 
  pushed, 
  by 
  means 
  of 
  the 
  electromagnet, 
  the 
  centre 
  

   of 
  the 
  luminous 
  mark 
  at 
  the 
  back 
  on 
  the 
  line 
  which 
  joined 
  

   the 
  reflector 
  to 
  the 
  small 
  cylinder. 
  

  

  