﻿808 
  

  

  Mr. 
  H. 
  L. 
  P. 
  Jolly 
  on 
  the 
  

  

  The 
  deflexion 
  was 
  taken 
  as 
  ° 
  ^ 
  ° 
  — 
  r. 
  

  

  Readings 
  

   for 
  press. 
  

  

  Means. 
  

  

  Number 
  

   cc 
  press. 
  

  

  Current. 
  

  

  Thermopile. 
  

  

  Pi 
  

  

  V 
  

  

  P 
  

  

  a 
  x 
  

  

  a 
  2 
  

  

  a 
  

  

  \ 
  

  

  r 
  o 
  

   r 
  ^ 
  

  

  r 
  

  

  r 
  o 
  

  

  

  T-2 
  

  

  

  

  b 
  i 
  

  

  G 
  i 
  

   d 
  x 
  

  

  C 
  2 
  

   d 
  2 
  

  

  b 
  

  

  c 
  

   d 
  

  

  1 
  

  

  }-Mean 
  

   1 
  

   J 
  

  

  r 
  2 
  

  

  r 
  3 
  

  

  r- 
  

  

  

  

  R. 
  

  

  The 
  results 
  of 
  one 
  series 
  o£ 
  such 
  readings 
  are 
  plotted 
  in 
  

   Curve 
  1 
  (PL 
  XIV.), 
  but 
  all 
  that 
  can 
  be 
  determined 
  from 
  it 
  

   (and 
  from 
  others 
  of 
  a 
  similar 
  nature) 
  is 
  a 
  general 
  increase 
  of 
  

   radiation 
  with 
  current, 
  the 
  relation 
  being 
  not 
  far 
  from 
  linear. 
  

  

  In 
  the 
  course 
  of 
  the 
  work 
  various 
  forms 
  of 
  discharge-tube 
  

   were 
  tried, 
  some 
  of 
  which 
  are 
  depicted 
  in 
  fig. 
  3 
  (PI. 
  XJIL). 
  

  

  A 
  plan 
  of 
  the 
  apparatus 
  used 
  in 
  the 
  foregoing 
  experiments 
  

   is 
  given 
  in 
  fig. 
  2 
  (PI. 
  XIII.) 
  . 
  

  

  4. 
  Experiments 
  with 
  a 
  Paschen 
  Galvanometer. 
  

  

  In 
  the 
  summer 
  of 
  1911 
  a 
  visit 
  was 
  paid 
  by 
  the 
  writer 
  to 
  

   the 
  laboratory 
  of 
  Prof. 
  Paschen 
  in 
  Tubingen, 
  for 
  the 
  purpose 
  

   of 
  procuring 
  a 
  sensitive 
  galvanometer. 
  

  

  The 
  galvanometer 
  is 
  essentially 
  of 
  the 
  Thomson 
  astatic 
  

   type, 
  and 
  every 
  conceivable 
  modification 
  tending 
  towards 
  

   increased 
  sensitiveness 
  has 
  been 
  made. 
  One 
  of 
  the 
  great 
  

   objects 
  in 
  view 
  is 
  the 
  decreasing 
  of 
  the 
  weight 
  and 
  moment 
  

   of 
  inertia 
  of 
  the 
  suspended 
  system, 
  

   so 
  that 
  a 
  given 
  sensitiveness 
  may 
  be 
  

   accompanied 
  by 
  as 
  small 
  a 
  period 
  of 
  

   oscillation 
  as 
  possible. 
  Fig. 
  4 
  repre- 
  

   sents 
  the 
  two 
  back 
  coils 
  with 
  the 
  

   suspended 
  system 
  when 
  the 
  front 
  pair 
  

   of 
  coils 
  has 
  been 
  removed. 
  A 
  section 
  

   through 
  these 
  coils 
  by 
  a 
  plane 
  at 
  

   right-angles 
  to 
  the 
  paper 
  is 
  drawn 
  at 
  

   the 
  side. 
  It 
  will 
  be 
  noticed 
  that 
  the 
  

   central 
  portion 
  of 
  the 
  coils 
  is 
  elliptical, 
  

   and 
  fits 
  exactly 
  the 
  outlines 
  of 
  the 
  

   magnet 
  systems. 
  The 
  other 
  concen- 
  

   tric 
  lines 
  mark 
  off 
  regions 
  in 
  which 
  

   different 
  thicknesses 
  ot 
  wire 
  are 
  used, 
  

  

  the 
  principle 
  being 
  that 
  for 
  every 
  increment 
  of 
  resistance 
  a 
  

   proportional 
  increase 
  is 
  made 
  in 
  the 
  galvanometer 
  constant. 
  

  

  