﻿the 
  Cathodic 
  Rays 
  and 
  those 
  of 
  Rontgen. 
  171 
  

  

  penetrated 
  in 
  it 
  likewise 
  through 
  the 
  vertical 
  tube 
  C. 
  But 
  

   on 
  the 
  part 
  of 
  the 
  bulb 
  facing 
  the 
  said 
  reflector 
  was 
  soldered 
  

   a 
  large 
  tube 
  M 
  closed 
  by 
  a 
  bimetallic 
  disk, 
  composed, 
  

   namely, 
  half 
  of 
  an 
  aluminium 
  sheet 
  of 
  the 
  thickness 
  of 
  half 
  

   a 
  millimetre, 
  and 
  the 
  other 
  half 
  also 
  of 
  a 
  sheet 
  of 
  aluminium 
  

   of 
  the 
  thickness 
  of 
  one 
  millimetre. 
  On 
  the 
  diameter 
  along 
  

   which 
  the 
  two 
  sheets 
  fitted 
  together 
  a 
  thick 
  sheet 
  of 
  zinc 
  was 
  

   soldered 
  perpendicularly 
  to 
  the 
  plane 
  of 
  the 
  disk. 
  

  

  In 
  front 
  of 
  both 
  the 
  two 
  sheets 
  that 
  formed 
  the 
  disk 
  a 
  small 
  

   photographic 
  cylinder 
  was 
  placed, 
  on 
  the 
  extremities 
  of 
  which 
  

   two 
  figures 
  were 
  respectively 
  fixed 
  ; 
  one 
  made 
  with 
  the 
  thinner 
  

   aluminium 
  sheet 
  (J 
  millimetre) 
  and 
  the 
  other 
  with 
  the 
  thicker 
  

   sheet 
  (1 
  millimetre). 
  

  

  Naturally 
  the 
  two 
  sides 
  of 
  the 
  cylindrical 
  surfaces, 
  wherein 
  

   the 
  figures 
  showed, 
  were 
  turned 
  towards 
  the 
  disk. 
  

  

  In 
  the 
  region 
  of 
  the 
  film 
  which 
  stood 
  opposite 
  the 
  two 
  thin 
  

   sheets 
  (the 
  thin 
  disk 
  and 
  figure 
  of 
  the 
  thin 
  sheet) 
  a 
  strong 
  

   impression 
  was 
  received 
  ; 
  whereas 
  on 
  the 
  points 
  placed 
  in 
  a 
  

   line 
  with 
  the 
  two 
  thicker 
  sheets 
  a 
  rather 
  feeble 
  one 
  was 
  

   obtained. 
  But 
  the 
  parts 
  where 
  the 
  figure 
  of 
  the 
  thin 
  sheet 
  

   fronted 
  the 
  thicker 
  half-disk 
  were 
  impressed 
  in 
  an 
  equal 
  

   degree 
  to 
  the 
  parts 
  placed 
  under 
  the 
  figure 
  of 
  the 
  thicker 
  

   sheet 
  and 
  the 
  thinner 
  half-disk. 
  

  

  The 
  same 
  results 
  were 
  obtained 
  when 
  the 
  tube 
  M 
  of 
  the 
  

   bulb 
  was 
  closed 
  by 
  disks 
  formed 
  (a) 
  half 
  of 
  aluminium 
  and 
  

   half 
  of 
  glass 
  of 
  the 
  same 
  thickness, 
  (b) 
  consisting 
  half 
  of 
  

   magnesium 
  and 
  half 
  of 
  glass 
  still 
  of 
  the 
  same 
  thickness. 
  

  

  1 
  also 
  tried 
  to 
  use 
  aluminium 
  and 
  zinc 
  ; 
  but 
  the 
  difference 
  

   between 
  the 
  impressions 
  derived 
  from 
  the 
  rays 
  emanating 
  from 
  

   both 
  the 
  one 
  and 
  the 
  other 
  metal 
  (of 
  equal 
  thickness) 
  was 
  so 
  

   great 
  that 
  no 
  decisive 
  result 
  was 
  obtainable. 
  

  

  15th 
  Experiment. 
  — 
  The 
  preceding 
  experiment 
  was 
  repeated, 
  

   the 
  cathodic 
  rays 
  striking 
  directly 
  on 
  the 
  metallic 
  disk. 
  

  

  The 
  result 
  was 
  the 
  same. 
  

  

  These 
  four 
  last 
  experiments 
  show 
  at 
  any 
  rate 
  very 
  approxi- 
  

   mately 
  that 
  the 
  transparencies 
  of 
  those 
  substances 
  which 
  are 
  

   photographically 
  efficacious 
  for 
  the 
  cathodic 
  rays 
  and 
  the 
  

   Rontgen 
  rays 
  have 
  the 
  same 
  value. 
  

  

  Conclusions. 
  

  

  From 
  the 
  bulk 
  of 
  the 
  experiments 
  above 
  described 
  it 
  seems 
  

   to 
  me 
  that 
  the 
  following 
  deductions 
  can 
  principally 
  be 
  drawn: 
  — 
  

  

  (a) 
  It 
  cannot 
  be 
  asserted 
  that 
  the 
  cathodic 
  rays 
  are 
  reflected, 
  

   as 
  a 
  whole, 
  according 
  to 
  the 
  laws 
  of 
  regular 
  reflexion. 
  

  

  (b'\ 
  The 
  rays 
  thrown 
  back 
  from 
  the 
  reflector 
  of 
  a 
  focus-tube 
  

  

  