﻿168 
  Prof. 
  A. 
  Battelli 
  on 
  the 
  Analogy 
  between 
  

  

  The 
  impression 
  on 
  the 
  photographic 
  cylinder 
  in 
  front 
  of 
  

   the 
  sheet 
  of 
  aluminium 
  was 
  very 
  slightly 
  more 
  intense 
  than 
  

   on 
  the 
  cylinder 
  placed 
  in 
  front 
  of 
  the 
  sheet 
  of 
  black 
  paper. 
  

   Whereas 
  in 
  the 
  cylinder 
  placed 
  behind 
  the 
  first 
  reflector 
  the 
  

   impression 
  appeared 
  sensibly 
  weaker 
  than 
  that 
  at 
  the 
  back 
  of 
  

   the 
  second. 
  

  

  8th 
  Experiment. 
  — 
  Still 
  the 
  same 
  arrangement 
  as 
  in 
  the 
  

   preceding 
  experiments. 
  The 
  reflector 
  of 
  one 
  of 
  the 
  bulbs 
  

   was 
  of 
  sheet 
  aluminium 
  of 
  t 
  ] 
  q 
  of 
  a 
  millimetre, 
  and 
  the 
  

   other 
  was 
  also 
  of 
  sheet 
  aluminium 
  of 
  yoVo 
  ^° 
  10V0 
  °f 
  a 
  

   millimetre. 
  

  

  The 
  electrical 
  discharge 
  was 
  sent 
  alternately 
  in 
  the 
  two 
  

   bulbs 
  with 
  intervals 
  of 
  two 
  seconds 
  each 
  time. 
  

  

  Of 
  the 
  films 
  in 
  front, 
  the 
  one 
  that 
  was 
  the 
  more 
  strongly 
  

   acted 
  on 
  was 
  the 
  one 
  facing 
  the 
  thicker 
  sheet, 
  and 
  the 
  reverse 
  

   effect 
  was 
  obtained 
  on 
  the 
  films 
  on 
  the 
  back. 
  

  

  Besides 
  this, 
  the 
  two 
  impressions 
  in 
  front 
  and 
  behind 
  the 
  

   very 
  thin 
  sheet 
  of 
  aluminium 
  were 
  very 
  nearly 
  of 
  the 
  same 
  

   intensity. 
  And, 
  lastly, 
  at 
  the 
  back 
  of 
  the 
  thin 
  sheet 
  the 
  usual 
  

   shadow 
  projected 
  in 
  the 
  focus-tube 
  by 
  the 
  reflector 
  was 
  no 
  

   longer 
  discernible. 
  

  

  Shortly 
  after 
  the 
  action 
  of 
  the 
  bulb, 
  the 
  sheet 
  of 
  aluminium 
  

   was 
  pierced 
  through 
  by 
  the 
  cathode 
  rays, 
  but 
  we 
  still 
  had 
  

   sufficient 
  time 
  to 
  complete 
  the 
  experiment. 
  

  

  The 
  same 
  experiment 
  with 
  similar 
  results 
  was 
  performed 
  

   w 
  T 
  ith 
  two 
  bulbs, 
  the 
  first 
  of 
  which 
  had 
  as 
  reflector 
  a 
  sheet 
  

   of 
  black 
  paper 
  of 
  the 
  thickness 
  of 
  -j§ 
  - 
  of 
  a 
  millimetre, 
  and 
  the 
  

   other 
  a 
  small 
  sheet 
  of 
  black 
  paper 
  even 
  thinner 
  than 
  t 
  Jq 
  of 
  a 
  

   millimetre. 
  

  

  9th 
  Experiment. 
  — 
  In 
  one 
  of 
  the 
  bulbs, 
  with 
  the 
  preceding 
  

   arrangement, 
  a 
  reflector 
  of 
  black 
  wove-paper 
  was 
  placed 
  of 
  the 
  

   thinness 
  of 
  less 
  than 
  T 
  ^ 
  (T 
  of 
  a 
  millimetre, 
  and 
  in 
  the 
  other 
  a 
  re- 
  

   flector 
  of 
  sheet 
  platinum 
  covered 
  with 
  the 
  same 
  thin 
  wove 
  paper. 
  

  

  In 
  front 
  of 
  the 
  two 
  surfaces 
  facing 
  the 
  cathode 
  an 
  impres- 
  

   sion 
  was 
  received 
  slightly 
  more 
  intense 
  on 
  the 
  film 
  facing 
  

   the 
  sheet 
  of 
  platinum, 
  whereas 
  in 
  front 
  of 
  the 
  opposed 
  surfaces 
  

   a 
  much 
  stronger 
  impression 
  was 
  naturally 
  received 
  on 
  the 
  

   other 
  film 
  belonging 
  to 
  the 
  sheet 
  of 
  the 
  thin 
  wove 
  paper. 
  

  

  The 
  experiments 
  from 
  5th 
  to 
  9th 
  included 
  prove, 
  not 
  only 
  

   that 
  the 
  photographic 
  action 
  on 
  the 
  sheet 
  struck 
  by 
  cathodic 
  

   ravs 
  is 
  much 
  more 
  intense 
  on 
  the 
  side 
  facing 
  the 
  cathode 
  than 
  

   on 
  the 
  contrary 
  one 
  (which 
  was 
  already 
  known), 
  but 
  they 
  

   demonstrate, 
  moreover, 
  that 
  the 
  agent 
  to 
  which 
  such 
  an 
  effect 
  

   is 
  due 
  is 
  the 
  more 
  fully 
  transmitted 
  from 
  the 
  first 
  face 
  to 
  the 
  

   second 
  the 
  thinner 
  the 
  stratum 
  is 
  which 
  is 
  to 
  be 
  penetrated, 
  

   and 
  the 
  less 
  dense 
  the 
  substance. 
  

  

  