﻿440 
  Mr. 
  C. 
  A. 
  Chant 
  : 
  An 
  Experimental 
  Investigation 
  

  

  It 
  would 
  naturally 
  be 
  suspected 
  that 
  this 
  reversal 
  effect 
  

   was 
  due 
  to 
  the 
  direct 
  action 
  of 
  the 
  coil 
  or 
  the 
  connecting 
  

   wires 
  ; 
  but 
  on 
  removing 
  the 
  cylinders 
  and 
  substituting 
  there- 
  

   for 
  small 
  knobs, 
  no 
  effect 
  was 
  obtained. 
  Indeed, 
  the 
  wings 
  

   of 
  the 
  detector 
  were 
  made 
  at 
  right 
  angles 
  to 
  the 
  wires 
  leading 
  

   from 
  the 
  coil 
  to 
  the 
  oscillator 
  in 
  order 
  to 
  avoid 
  such 
  action. 
  

   Moreover, 
  if 
  it 
  were 
  due 
  to 
  the 
  direct 
  action, 
  the 
  effect 
  would 
  

   have 
  been 
  more 
  pronounced 
  with 
  the 
  spherical 
  oscillators, 
  but 
  

   such 
  was 
  not 
  the 
  case. 
  

  

  The 
  readings 
  in 
  the 
  table 
  show 
  irregularity 
  in 
  the 
  action 
  

   of 
  the 
  oscillators, 
  though 
  I 
  believe 
  it 
  is 
  not 
  so 
  great 
  as 
  in 
  many 
  

   experiments 
  with 
  electric 
  waves, 
  a 
  fact 
  due 
  largely 
  to 
  the 
  

   constancy 
  of 
  the 
  interrupter 
  used. 
  

  

  In 
  Table 
  IV. 
  readings 
  obtained 
  with 
  various 
  cylinders 
  are 
  

   exhibited. 
  Each 
  reading 
  is 
  the 
  mean 
  of 
  the 
  two 
  readings 
  

   obtained, 
  at 
  the 
  distance 
  indicated, 
  by 
  the 
  detector 
  in 
  its 
  two 
  

   positions. 
  An 
  examination 
  of 
  the 
  results 
  will 
  lead 
  to 
  the 
  

   conclusion 
  that, 
  for 
  frequencies 
  as 
  high 
  as 
  those 
  here 
  used, 
  

   the 
  effectiveness 
  of 
  an 
  oscillator 
  is 
  not 
  impaired 
  by 
  using 
  a 
  

   thin 
  shell 
  instead 
  of 
  a 
  solid. 
  

  

  As 
  stated 
  above, 
  the 
  platinum 
  caps 
  were 
  soldered 
  to 
  the 
  

   iron 
  and 
  brass 
  cylinders, 
  and 
  were 
  then 
  given 
  an 
  excellent 
  

   polish. 
  The 
  caps 
  on 
  the 
  gold-leaf 
  and 
  other 
  delicate 
  shells 
  

   could 
  not 
  be 
  polished 
  in 
  this 
  way. 
  They 
  were 
  simply 
  rubbed 
  

   clean 
  with 
  chamois. 
  One 
  would 
  naturally 
  expect, 
  therefore, 
  

   that 
  the 
  solid 
  cylinders 
  would 
  perform 
  best, 
  but 
  such 
  was 
  not 
  

   the 
  case. 
  Indeed 
  the 
  brass 
  and 
  iron 
  oscillators 
  were 
  the 
  

   hardest 
  to 
  adjust 
  and 
  seemed 
  about 
  the 
  least 
  effective 
  ; 
  and 
  

   the 
  gold-leaf 
  acted 
  so 
  continuously 
  better 
  than 
  the 
  solid, 
  that 
  

   I 
  began 
  to 
  think 
  its 
  thinness 
  was 
  a 
  determining 
  factor. 
  The 
  

   average 
  of 
  the 
  readings 
  for 
  gold-leaf 
  given 
  in 
  the 
  table 
  is 
  

   decidedly 
  better 
  than 
  for 
  the 
  brass 
  oscillator, 
  and 
  numerous 
  

   readings 
  accentuated 
  this 
  result. 
  Afterwards, 
  however, 
  the 
  

   platinum 
  shell 
  (No. 
  6) 
  was 
  constructed, 
  and 
  proved 
  the 
  most 
  

   reliable 
  and 
  efficient 
  of 
  all. 
  Now 
  this 
  shell 
  was 
  thicker 
  than 
  

   the 
  calculated 
  * 
  skin 
  ' 
  (Table 
  1.) 
  , 
  and 
  further, 
  on 
  wrapping 
  two 
  

   layers 
  of 
  heavy 
  tinfoil 
  (thickness 
  0*005 
  cm.) 
  about 
  the 
  

   mantle 
  and 
  binding 
  it 
  closely 
  there, 
  no 
  alteration 
  whatever 
  

   was 
  made 
  in 
  its 
  efficiency. 
  The 
  proper 
  conclusion, 
  therefore, 
  

   seemed 
  to 
  be 
  that, 
  within 
  the 
  limits 
  of 
  the 
  experiments, 
  the 
  

   thickness 
  of 
  the 
  metal 
  had 
  no 
  effect. 
  

  

  If 
  one 
  could 
  obtain 
  a 
  thin 
  continuous 
  carbon 
  shell 
  possibly 
  

   more 
  decisive 
  experiments 
  might 
  be 
  made, 
  as 
  the 
  ' 
  skin 
  ' 
  for 
  

   carbon 
  is 
  comparatively 
  thick, 
  but 
  such 
  was 
  not 
  available. 
  

  

  The 
  magnetic 
  nature 
  of 
  the 
  iron 
  made 
  no 
  difference 
  what 
  

   ever 
  ; 
  iron 
  and 
  brass 
  were 
  indistinguishable 
  in 
  their 
  behaviour. 
  

   Silver 
  did 
  not 
  appear 
  equal 
  to 
  platinum 
  as 
  a 
  spark-surface. 
  

  

  