﻿188 
  Messrs. 
  Trowbridge 
  and 
  Burbank 
  on 
  

  

  tube 
  ; 
  in 
  addition, 
  a 
  brilliant 
  fluorescence 
  filled 
  tbe 
  side 
  tube, 
  

   which 
  appeared 
  to 
  flow 
  in 
  or 
  flow 
  out 
  of 
  the 
  narrow 
  tube 
  which 
  

   ended 
  in 
  the 
  small 
  bulb. 
  We 
  were 
  reminded 
  by 
  this 
  phe- 
  

   nomenon 
  of 
  Poynting's 
  hypothesis 
  of 
  the 
  flow 
  of 
  energy 
  into 
  a 
  

   wire. 
  This 
  form 
  of 
  tube 
  was 
  replaced 
  by 
  a 
  straight-wire 
  tube 
  

   which 
  is 
  represented 
  in 
  fig. 
  4 
  and 
  fig. 
  5 
  (side 
  view). 
  A 
  straight 
  

   wire 
  passed 
  completely 
  through 
  the 
  tube, 
  and 
  was 
  in 
  circuit 
  

   with 
  a 
  line 
  on 
  which 
  there 
  was 
  a 
  rapid 
  change 
  of 
  potential. 
  

   At 
  one 
  end 
  of 
  this 
  tube 
  opposite 
  a 
  thin 
  bulb 
  blown 
  on 
  the 
  

   tube 
  was 
  a 
  piece 
  of 
  platinum 
  foil 
  inclined 
  like 
  the 
  ordinary 
  

   focus-plane 
  in 
  a 
  focus-tube. 
  At 
  first 
  we 
  connected 
  this 
  focus- 
  

   plane 
  with 
  the 
  ground, 
  and 
  having 
  ascertained 
  that 
  #-rays 
  

   were 
  given 
  off 
  very 
  strongly 
  from 
  this 
  platinum, 
  we 
  removed 
  

   the 
  ground 
  connexion 
  and 
  substituted 
  for 
  it 
  a 
  sheet 
  of 
  zinc. 
  

   The 
  tube 
  still 
  gave 
  off 
  #-rays. 
  We 
  then 
  removed 
  the 
  sheet 
  

   of 
  zinc 
  and 
  found 
  that 
  #-rays 
  were 
  given 
  off 
  with 
  undiminished 
  

   strength. 
  This 
  tube 
  was 
  then 
  modified 
  into 
  the 
  form 
  repre- 
  

   sented 
  in 
  fig. 
  6, 
  fig. 
  7 
  (side 
  view). 
  The 
  straight 
  wire 
  occupied 
  

   the 
  middle 
  of 
  a 
  tube 
  ; 
  in 
  one 
  end 
  of 
  this 
  tube 
  was 
  placed 
  a 
  

   focus-plane 
  of 
  platinum, 
  and 
  at 
  the 
  other 
  there 
  was 
  a 
  long 
  

   narrow 
  tube 
  which 
  ended 
  in 
  a 
  thin 
  bulb. 
  In 
  this 
  bulb 
  was 
  a 
  

   crystal 
  of 
  calcite, 
  which 
  was 
  confined 
  in 
  the 
  tube 
  by 
  the 
  

   narrowness 
  of 
  the 
  bore 
  of 
  the 
  connecting 
  tube. 
  The 
  tube 
  

   showed 
  that 
  #-rays 
  were 
  given 
  off 
  at 
  right 
  angles 
  to 
  the 
  

   straight 
  wire, 
  for 
  the 
  calcite 
  fluoresced 
  a 
  brilliant 
  red, 
  and 
  

   the 
  fluoroscope 
  showed 
  ^?-rays 
  proceeding 
  from 
  the 
  inclined 
  

   piece 
  of 
  platinum. 
  This 
  form 
  of 
  tube, 
  moreover, 
  showed 
  that 
  

   the 
  #-rays 
  are 
  reflected, 
  so 
  to 
  speak, 
  from 
  the 
  interior 
  surface 
  

   of 
  the 
  glass, 
  for 
  there 
  were 
  multiple 
  shadows 
  of 
  the 
  wire 
  on 
  

   the 
  sides 
  of 
  the 
  tube 
  which 
  were 
  produced 
  by 
  the 
  #-rays 
  of 
  

   varying 
  intensity 
  which 
  were 
  developed 
  on 
  the 
  surface 
  of 
  the 
  

   glass, 
  and 
  which 
  in 
  turn 
  proceeding 
  from 
  this 
  surface 
  at 
  

   different 
  angles 
  produced 
  elongated 
  shadows. 
  In 
  the 
  next 
  

   form 
  of 
  tube 
  the 
  wire 
  passing 
  through 
  the 
  tube 
  was 
  no 
  longer 
  

   straight, 
  but 
  was 
  bent 
  in 
  the 
  manner 
  represented 
  in 
  fig. 
  8. 
  In 
  

   this 
  form 
  of 
  tube 
  there 
  was 
  a 
  brilliant 
  caustic 
  formed 
  on 
  the 
  

   side 
  of 
  the 
  tube 
  opposite 
  the 
  concave 
  side 
  of 
  the 
  wire, 
  and 
  

   this 
  brilliant 
  caustic 
  threw 
  distorted 
  shadows 
  of 
  the 
  bent 
  wire 
  

   on 
  the 
  opposite 
  side 
  of 
  the 
  tube. 
  It 
  was 
  evident 
  that 
  the 
  

   .y-rays 
  were 
  given 
  off 
  at 
  right 
  angles 
  to 
  the 
  surface 
  of 
  this 
  

   wire, 
  and 
  therefore 
  coincided 
  in 
  direction 
  with 
  the 
  lines 
  of 
  

   electrostatic 
  force. 
  

  

  We 
  next 
  experimented 
  with 
  the 
  form 
  of 
  tube 
  represented 
  

   in 
  fig. 
  9. 
  This 
  consisted 
  of 
  a 
  large 
  thin 
  bulb 
  5 
  inches 
  in 
  

   diameter, 
  enclosing 
  a 
  continuous 
  conductor, 
  the 
  centre 
  of 
  

   which 
  consisted 
  of 
  an 
  aluminium 
  mirror. 
  When 
  this 
  tube 
  

  

  