﻿96 
  

  

  Prof. 
  L. 
  R. 
  Ingersoll 
  on 
  Magnetic 
  

  

  R 
  parts 
  of 
  energy 
  which 
  are 
  reflected 
  and 
  go 
  to 
  make 
  up 
  the 
  

   measured 
  quantity 
  I, 
  R' 
  parts 
  are 
  inactive, 
  having 
  suffered 
  

   no 
  rotation 
  and 
  hence 
  should 
  be 
  subtracted 
  from 
  I 
  in 
  computing 
  

   the 
  actual 
  rotation. 
  This 
  is 
  equivalent 
  to 
  multiplying 
  the 
  

   rotation, 
  measured 
  in 
  the 
  ordinary 
  way 
  as 
  dlll^ 
  by 
  

  

  R/(R-R')- 
  

  

  When 
  there 
  is 
  added 
  to 
  this 
  the 
  doubled 
  rotation 
  due 
  to 
  the 
  

   passage 
  twice 
  through 
  the 
  glass 
  the 
  corrected 
  rotation 
  is 
  

   obtained. 
  To 
  take 
  the 
  first 
  case 
  in 
  Table 
  JY. 
  as 
  an 
  example,. 
  

  

  Table 
  lY. 
  

  

  Reflexion 
  rotations 
  from 
  the 
  rear 
  (glass-metaD 
  surfaces 
  

   of 
  pure 
  iron 
  films 
  15, 
  17, 
  22. 
  

  

  X. 
  

  

  Measured 
  

   rotation. 
  

  

  E. 
  

  

  E'. 
  

  

  a 
  . 
  

  

  Double 
  

  

  glass 
  

   rotation. 
  

  

  Corrected 
  

   rotation. 
  

  

  

  

  

  Film 
  15 
  

  

  . 
  

  

  

  

  •63/i 
  

  

  -•262° 
  

  

  •321 
  

  

  •040 
  

  

  -•299° 
  

  

  •143° 
  

  

  -•442° 
  

  

  •74 
  

  

  -•348 
  

  

  •328 
  

  

  •040 
  

  

  -•396 
  

  

  •108 
  

  

  -•504 
  

  

  •94 
  

  

  -•480 
  

  

  •340 
  

  

  •U39 
  

  

  -•543 
  

  

  •070 
  

  

  -•613 
  

  

  1-28 
  

  

  -•610 
  

  

  •335 
  

  

  •039 
  

  

  -•691 
  

  

  •037 
  

  

  -•728 
  

  

  1-71 
  

  

  -•662 
  

  

  •335 
  

  

  •038 
  

  

  -•747 
  

  

  •019 
  

  

  -•766 
  

  

  2-14 
  

  

  -•656 
  

  

  •336 
  

  

  ] 
  

  

  •038 
  

  

  Film 
  17 
  

  

  -•740 
  

  

  •009 
  

  

  -•749 
  

  

  •66/x 
  

  

  -•211° 
  

  

  •257 
  

  

  •040 
  

  

  -•250° 
  

  

  •133° 
  

  

  -•383° 
  

  

  •75 
  

  

  -•312 
  

  

  •259 
  

  

  040 
  

  

  -•369 
  

  

  •100 
  

  

  -•469 
  

  

  •96 
  

  

  -•414 
  

  

  •247 
  

  

  •039 
  

  

  -•492 
  

  

  •066 
  

  

  -•558 
  

  

  1-30 
  

  

  -•517 
  

  

  •229 
  

  

  •039 
  

  

  -•624 
  

  

  •033 
  

  

  -•657 
  

  

  1-74 
  

  

  -•570 
  

  

  •215 
  

  

  •038 
  

  

  -•693 
  

  

  •016 
  

  

  -•709 
  

  

  216 
  

  

  -•567 
  

  

  •191 
  

  

  ] 
  

  

  •038 
  

   Film 
  22 
  

  

  -•708 
  

  

  •009 
  

  

  -•717 
  

  

  ■mil 
  

  

  -•084° 
  

  

  •090 
  

  

  •040 
  

  

  -•152° 
  

  

  •133° 
  

  

  -•285° 
  

  

  •75 
  

  

  -•181 
  

  

  •088 
  

  

  •040 
  

  

  -•332 
  

  

  •100 
  

  

  -•432 
  

  

  •96 
  

  

  -•314 
  

  

  •080 
  

  

  •039 
  

  

  -•613 
  

  

  •066 
  

  

  -•679 
  

  

  1^30 
  

  

  -•414 
  

  

  •081 
  

  

  •039 
  

  

  -•798 
  

  

  •033 
  

  

  -•831 
  

  

  1^74 
  

  

  -•459 
  

  

  •075 
  

  

  •038 
  

  

  -•930 
  

  

  •016 
  

  

  -•946 
  

  

  2-16 
  

  

  -•430 
  

  

  •070 
  

  

  •038 
  

  

  -•940 
  

  

  •009 
  

  

  -•949 
  

  

  the 
  measured 
  rotation 
  ( 
  = 
  45/7r<iI/I) 
  for 
  X 
  = 
  -63yLt 
  was 
  found 
  

   to 
  be 
  — 
  '262°. 
  The 
  reflecting 
  power 
  of 
  the 
  glass 
  and 
  glass- 
  

   metal 
  surfaces 
  was 
  '321 
  and 
  that 
  of 
  the 
  glass 
  alone 
  (there 
  

   being 
  no 
  liquid 
  in 
  this 
  case) 
  was 
  '040. 
  This 
  gives 
  a 
  correcting 
  

  

  