﻿the 
  Cathodic 
  Rays 
  and 
  those 
  of 
  Rontgen. 
  165 
  

  

  Finally, 
  the 
  tube 
  D 
  was 
  kept 
  in 
  permanent 
  communication 
  

   with 
  the 
  air-pump. 
  

  

  Fiar. 
  1. 
  

  

  By 
  means 
  of 
  this 
  arrangement 
  the 
  conditions 
  of 
  the 
  

   apparatus 
  could 
  rapidly 
  be 
  changed, 
  and 
  on 
  the 
  other 
  hand 
  

   the 
  closure 
  of 
  the 
  tube 
  C 
  and 
  the 
  communication 
  of 
  the 
  tube 
  

   D 
  with 
  the 
  air-pump 
  were 
  established 
  in 
  a 
  perfect 
  manner 
  

   and 
  with 
  much 
  rapidity, 
  by 
  means 
  of 
  joints 
  surrounded 
  with 
  

   mercury, 
  as 
  indicated 
  in 
  the 
  figure. 
  With 
  these 
  tubes 
  I 
  

   performed 
  the 
  following 
  series 
  of 
  experiments 
  : 
  — 
  ■ 
  

  

  1st 
  Experiment. 
  — 
  The 
  small 
  reflector 
  was 
  a 
  plate 
  of 
  pla- 
  

   tinum, 
  and 
  besides 
  the 
  two 
  small 
  cylinders 
  c 
  and 
  d 
  situated 
  

   in 
  front 
  and 
  at 
  the 
  back 
  of 
  the 
  same 
  small 
  reflector, 
  other 
  

   three 
  were 
  placed 
  in 
  front 
  laterally 
  to 
  c 
  distributed 
  at 
  equal 
  

   intervals 
  between 
  c 
  and 
  the 
  surface 
  of 
  the 
  reflector, 
  all 
  at 
  

   nearly 
  the 
  same 
  distance 
  from 
  the 
  point 
  struck 
  by 
  the 
  small 
  

   pencil 
  of 
  cathodic 
  rays. 
  The 
  experiment 
  was 
  conducted 
  

   under 
  the 
  influence 
  of 
  both 
  high 
  and 
  medium 
  rarefaction, 
  

   and 
  an 
  impression 
  was 
  invariably 
  obtained 
  on 
  all 
  the 
  films 
  

   placed 
  in 
  front 
  of 
  the 
  platinum 
  reflector, 
  which 
  impression 
  

   gradually 
  diminished 
  in 
  strength 
  from 
  the 
  film 
  c 
  towards 
  

   the 
  one 
  placed 
  in 
  the 
  plane 
  of 
  the 
  reflector 
  *. 
  In 
  this 
  last 
  

  

  * 
  Whenever 
  I 
  speak 
  of 
  a 
  photographic 
  impression 
  on 
  a 
  film 
  placed 
  in 
  

   front 
  or 
  at 
  the 
  back 
  of 
  the 
  reflector 
  of 
  a 
  focus-tnbe, 
  I 
  mean 
  to 
  indicate 
  

   the 
  impression 
  on 
  that 
  part 
  of 
  the 
  film 
  that 
  was 
  facing 
  the 
  reflector, 
  

   because 
  in 
  any 
  other 
  part 
  of 
  the 
  same 
  film 
  the 
  impression 
  was 
  always 
  

   very 
  faint 
  or 
  small. 
  

  

  