﻿Rotation 
  hi 
  Iron 
  Cathode 
  Films. 
  

  

  81 
  

  

  one 
  o£ 
  the 
  two 
  beams 
  being 
  used. 
  It 
  was 
  mounted 
  in 
  a 
  

   massive 
  brass 
  conical 
  bearing 
  B, 
  and 
  could 
  be 
  rotated 
  bj 
  a 
  

   micrometer 
  tangent 
  screw 
  to 
  produce 
  an 
  accurately 
  known 
  

   mechanical 
  rotation 
  o£ 
  the 
  plane 
  of 
  polarization, 
  as 
  mentioned 
  

   above. 
  The 
  analyser, 
  A, 
  was 
  a 
  slightly 
  larger 
  double 
  image 
  

   prism 
  of 
  5 
  cm. 
  aperture. 
  

  

  Spectrometer. 
  — 
  The 
  two 
  images 
  (o£ 
  the 
  glower) 
  from 
  the 
  

   analyser, 
  each 
  about 
  1 
  cm. 
  long, 
  fell 
  vertically 
  over 
  one 
  

   another 
  on 
  the 
  two 
  parts 
  into 
  which 
  the 
  slit 
  was 
  divided 
  by 
  

   the 
  diaphragms 
  D, 
  I) 
  (fig. 
  2) 
  ; 
  and 
  shutters, 
  Sh, 
  allowed 
  

  

  Fig. 
  2. 
  — 
  The 
  slit 
  and 
  its 
  accessories. 
  

  

  each 
  beam 
  to 
  be 
  cut 
  ojBF 
  separately. 
  The 
  sliding 
  shade, 
  SI, 
  was 
  

   necessary 
  for 
  the 
  following 
  reason: 
  — 
  It 
  was 
  required 
  that 
  

   the 
  initial 
  intensities 
  of 
  the 
  two 
  spectra 
  as 
  they 
  fell 
  on 
  the 
  

   bolometer 
  strips 
  should 
  be 
  equal. 
  This 
  was 
  accomplished 
  by 
  

   Phil 
  Mag. 
  S. 
  6. 
  Vol. 
  18. 
  Xo. 
  103. 
  July 
  1909.' 
  G 
  

  

  