﻿Prof. 
  A. 
  Koiti 
  on 
  the 
  iL-Rays 
  and 
  the 
  Cathodic 
  Beam. 
  507 
  

  

  said 
  to 
  be 
  incapable 
  of 
  producing 
  #-rays, 
  and 
  because 
  they 
  did 
  

   not 
  arise 
  from 
  the 
  impinging 
  pencil 
  either 
  through 
  regular 
  

   reflexion 
  or 
  through 
  diffusion. 
  

  

  11. 
  It 
  must 
  be 
  remembered, 
  however, 
  that 
  photographs 
  

   of 
  the 
  tube, 
  taken 
  with 
  a 
  camera 
  without 
  lens, 
  show 
  that 
  

   some 
  #-rays, 
  weak 
  ones 
  it 
  is 
  true, 
  also 
  start 
  from 
  all 
  the 
  

   surface 
  of 
  the 
  glass 
  rendered 
  fluorescent 
  by 
  the 
  so-called 
  

   internal 
  rays 
  ; 
  and 
  I 
  have 
  already 
  shown 
  that 
  their 
  non- 
  

   observauce 
  of 
  the 
  laws 
  of 
  reflexion 
  does 
  not 
  seem 
  a 
  sufficient 
  

   reason 
  for 
  making 
  a 
  distinction 
  between 
  these 
  rays 
  and 
  the 
  

   cathode-rays 
  properly 
  so-called. 
  And 
  let 
  it 
  be 
  remembered 
  

   that 
  whilst 
  the 
  cathode-rays 
  cause 
  a 
  marked 
  fluorescence 
  in 
  

   glass, 
  I 
  have 
  assured 
  myself 
  that 
  ^-rays 
  cause 
  almost 
  none, 
  

   even 
  when 
  their 
  point 
  of 
  departure 
  is 
  an 
  anticathode 
  of 
  

   aluminium 
  serving 
  as 
  a 
  dividing 
  wall, 
  so 
  that 
  they 
  have 
  not 
  

   already 
  passed 
  through 
  glass. 
  

  

  II. 
  

  

  I 
  pass 
  to 
  the 
  promised 
  experiments, 
  which, 
  as 
  I 
  think, 
  

   would 
  alone 
  suffice 
  to 
  exclude 
  the 
  idea 
  that 
  the 
  #-rays 
  are 
  

   derived 
  from 
  the 
  cathodic 
  pencil 
  by 
  a 
  simple 
  process 
  of 
  sub- 
  

   traction. 
  

  

  The 
  tube, 
  represented 
  by 
  fig. 
  1 
  at 
  one 
  Fig. 
  1. 
  

  

  third 
  the 
  natural 
  size, 
  contained 
  the 
  ordinary 
  

   aluminium 
  cathode, 
  and 
  was 
  closed 
  by 
  a 
  

   disk 
  also 
  of 
  aluminium 
  held 
  tight 
  against 
  

   the 
  glass 
  edge, 
  which 
  had 
  been 
  ground. 
  

   Against 
  the 
  disk 
  was 
  placed 
  a 
  leaden 
  

   diaphragm 
  pierced 
  by 
  a 
  hole 
  of 
  1 
  centim. 
  

   in 
  diameter, 
  so 
  that 
  only 
  the 
  central 
  rays 
  

   given 
  out 
  by 
  the 
  disk, 
  which 
  acted 
  as 
  

   anticathode 
  and 
  as 
  anode, 
  reached 
  the 
  

   actinometer*; 
  and 
  the 
  other 
  face 
  of 
  the 
  

   aciinometer, 
  protected 
  by 
  glasses 
  of 
  cobalt, 
  

   received 
  the 
  light 
  from 
  an 
  incandescent 
  

   lamp. 
  A 
  permanent 
  magnet 
  being 
  advanced 
  

   towards 
  the 
  tube, 
  between 
  cathode 
  and 
  

   anticathode, 
  the 
  cathodic 
  pencil 
  was 
  directed 
  

   on 
  to 
  the 
  lateral 
  wall, 
  and 
  the 
  maximum 
  

   and 
  minimum 
  fluorescence 
  observed 
  by 
  

   Birkenlandf 
  were 
  distinctly 
  visible 
  at 
  F. 
  

  

  The 
  deflexion 
  of 
  the 
  internal 
  pencil 
  wad 
  

   accompanied 
  by 
  a 
  great 
  darkening 
  of 
  the 
  

   face 
  of 
  the 
  actinometer 
  covered 
  with 
  

  

  * 
  L' 
  Elettricista, 
  Year 
  V. 
  p. 
  197. 
  

  

  t 
  " 
  Sur 
  mi 
  Spectre 
  des 
  "Rayons 
  cathodiques," 
  Compt. 
  Rend. 
  vol. 
  cxxiii. 
  

   p. 
  492. 
  

  

  •£;■,..,/'■;« 
  ,./,a 
  iMU 
  

  

  -zm 
  

  

  