﻿714 
  Mr. 
  H. 
  B. 
  Keene 
  on 
  the 
  

  

  The 
  same 
  narrow 
  pencil 
  of 
  X 
  rays 
  was 
  allowed 
  to 
  fall 
  

   normally 
  upon 
  thin 
  sheets 
  of 
  various 
  metals. 
  The 
  photo- 
  

   graphic 
  plate 
  was 
  placed 
  in 
  the 
  path 
  of 
  the 
  emergent 
  beam, 
  

   and 
  in 
  a 
  plane 
  parallel 
  to 
  that 
  of 
  the 
  absorbing 
  metal 
  sheet 
  

   (see 
  fig. 
  2). 
  The 
  distance 
  of 
  the 
  plate 
  from 
  the 
  sheet 
  was 
  

  

  Fig. 
  2. 
  

  

  -j: 
  

  

  w 
  

  

  ^JL 
  

  

  MM 
  MST&L 
  SHE6T 
  

   VP 
  PHOTOGRAPHIC 
  T»UT£ 
  

  

  25 
  mm. 
  In 
  all 
  cases 
  the 
  metal 
  sheets 
  were 
  so 
  thin 
  that 
  

   the 
  greater 
  part 
  of 
  the 
  radiation 
  passed 
  directly 
  through 
  

   them, 
  and 
  gave 
  rise 
  to 
  an 
  intense 
  circular 
  spot 
  on 
  the 
  photo- 
  

   graphic 
  plate. 
  A 
  portion 
  of 
  the 
  remainder 
  gave 
  rise 
  to 
  

   drawn 
  out 
  spots 
  or 
  other 
  markings 
  surrounding 
  the 
  central 
  

   spot 
  due 
  to 
  the 
  primary 
  beam. 
  

  

  As 
  many 
  of 
  the 
  negatives 
  are 
  unsuitable 
  for 
  reproduction 
  

   owing 
  to 
  the 
  fogging 
  produced 
  by 
  the 
  general 
  scattering, 
  

   the 
  nature 
  of 
  the 
  results 
  are 
  indicated 
  in 
  the 
  accompanying 
  

   diagrams, 
  jrjp- 
  3. 
  

  

  Fig. 
  3 
  shows 
  the 
  result 
  obtained 
  w 
  T 
  ith 
  t 
  

  

  Russian 
  sheet-iron 
  (thickness==0'4mm.). 
  ^ 
  y»f 
  V 
  '/'/'f 
  ^ 
  

  

  It 
  will 
  be 
  seen 
  that 
  the 
  streaks 
  are 
  - 
  n^ 
  v 
  j^ 
  

  

  radial, 
  the 
  majority 
  of 
  them 
  lying 
  on 
  a 
  "^ 
  

   circle 
  representing 
  a 
  deflexion 
  from 
  the 
  "^T 
  

   direction 
  of 
  the 
  primary 
  beam 
  of 
  about 
  ^// 
  1 
  o*^ 
  

  

  10°. 
  The 
  interior 
  of 
  this 
  halo 
  is 
  quite 
  ' 
  VmV 
  v 
  ^ 
  

  

  clear, 
  while 
  outside 
  it 
  fainter 
  streaks 
  f 
  * 
  

  

  are 
  visible. 
  An 
  attempt 
  to 
  distort 
  the 
  Fig. 
  4. 
  

  

  pattern 
  by 
  placing 
  the 
  specimen 
  between 
  ^ 
  | 
  t« 
  v 
  // 
  

  

  the 
  poles 
  of 
  a 
  powerful 
  electromagnet 
  *v 
  ^\nv\iW 
  ^y 
  > 
  

   during 
  another 
  exposure, 
  gave 
  a 
  nega- 
  ^o^ 
  v 
  * 
  *+&Ja 
  

   five 
  result. 
  ; 
  *-"5^r 
  

  

  Fig. 
  4 
  shows 
  the 
  distribution 
  of 
  the 
  'J-5!" 
  

   emergent 
  radiation 
  from 
  cobalt 
  (0*25 
  mm. 
  <§§' 
  

   thick). 
  In 
  this 
  case 
  the 
  streaks 
  are 
  ^A/iil^V 
  

   smaller 
  and 
  more 
  closely 
  packed. 
  vM'r 
  ■ 
  , 
  ^ 
  

  

  