﻿60 
  Z. 
  DeForest 
  — 
  Reflection 
  of 
  Hertzian 
  Tf 
  

  

  aves. 
  

  

  centered 
  at 
  a 
  focus 
  of 
  the 
  ellipse 
  together 
  v/ith 
  the 
  leading-in 
  

   wires. 
  Thus 
  reflections 
  from 
  every 
  part 
  of 
  the 
  edges 
  of 
  the 
  

   plates 
  were 
  concentrated 
  simultaneously 
  at 
  the 
  gap. 
  

  

  The 
  spark 
  gap 
  between 
  these 
  two 
  balls 
  varied 
  from 
  l™"" 
  to 
  

   2™". 
  About 
  this 
  primary 
  oscillator 
  a 
  similar 
  zinc 
  strip 
  32*='" 
  

   long 
  was 
  bent 
  to 
  form 
  the 
  secondary. 
  The 
  whole 
  was 
  im- 
  

   mersed 
  in 
  a 
  glass 
  vessel 
  containing 
  kerosene 
  oil. 
  But 
  0*5^"^ 
  

   separated 
  the 
  primary 
  from 
  secondary, 
  and 
  without 
  the 
  oil 
  

   violent 
  spark 
  discharges 
  passed 
  between 
  all 
  parts 
  of 
  the 
  system. 
  

   The 
  petroleum 
  was 
  decomposed 
  by 
  the 
  electrical 
  action, 
  carbon 
  

   being 
  deposited 
  upon 
  the 
  zincs. 
  This 
  oil 
  was 
  renewed 
  from 
  

   time 
  to 
  time. 
  

  

  This 
  particular 
  arrangement 
  combines 
  advantages 
  of 
  both 
  

   the 
  Lecher 
  and 
  Blondlot 
  exciters. 
  By 
  the 
  use 
  of 
  plates 
  all 
  the 
  

   elements 
  of 
  the 
  primary 
  and 
  secondary 
  may 
  be 
  brought 
  closer, 
  

   the 
  loss 
  of 
  energy 
  found 
  in 
  the 
  Lecher 
  exciter 
  obviated 
  ; 
  and 
  the 
  

   uninterrupted 
  form 
  of 
  the 
  secondary 
  connects 
  the 
  two 
  parallel 
  

   wires 
  as 
  in 
  the 
  Blondlot, 
  allowing 
  perfect 
  reflection 
  or 
  inter- 
  

   changing 
  of 
  the 
  back-coming 
  waves 
  from 
  DD^ 
  Moreover, 
  the 
  

   damping 
  of 
  this 
  oscillator 
  was 
  such 
  that 
  its 
  individual 
  period 
  

   had 
  little 
  effect 
  upon 
  the 
  resonator 
  system 
  of 
  the 
  wires. 
  I 
  

   could 
  by 
  judicious 
  bridging 
  get 
  almost 
  any 
  wave-length 
  from 
  

   50^"" 
  to 
  3 
  meters. 
  The 
  case 
  was 
  analogous 
  to 
  that 
  of 
  any 
  

   acoustic 
  vibrating 
  system 
  when 
  struck 
  by 
  a 
  body 
  of 
  any 
  period 
  

   whatsoever 
  — 
  the 
  primary 
  oscillation 
  caused 
  by 
  the 
  spark 
  dis- 
  

   charge 
  serving 
  merely 
  to 
  excite 
  surgings 
  in 
  D 
  B 
  D', 
  the 
  period 
  

   of 
  which 
  is 
  determined 
  by 
  the 
  location 
  of 
  the 
  first 
  bridge 
  on 
  

   DD^ 
  

  

  When 
  the 
  length 
  of 
  the 
  wires 
  DD' 
  is 
  properly 
  proportioned 
  

   to 
  the 
  period 
  of 
  the 
  exciter, 
  we 
  have 
  of 
  course 
  the 
  st]'ongest 
  

   possible 
  action. 
  With 
  a 
  first 
  bridge 
  at 
  36^"" 
  from 
  S, 
  and 
  suc- 
  

   ceeding 
  ones 
  43-44"='" 
  apart, 
  the 
  vacuum 
  tube, 
  laid 
  across 
  the 
  

   ends 
  of 
  the 
  wires 
  to 
  serve 
  as 
  a 
  detector, 
  was 
  found 
  to 
  glow 
  with 
  

   eight 
  bridges 
  on 
  the 
  wires. 
  

  

  For 
  any 
  other 
  wave-length 
  so 
  great 
  a 
  number 
  of 
  bridges 
  

   quite 
  extinguished 
  the 
  effect 
  of 
  the 
  primary 
  vibrations. 
  I 
  

   regarded 
  then 
  86-88*='" 
  as 
  the 
  primary 
  wave-length 
  ; 
  the 
  

   natural 
  period, 
  calculated,"^" 
  is 
  60*='" 
  in 
  oil, 
  giving 
  86-4*='" 
  in 
  air. 
  

  

  A 
  certain 
  dim 
  glow 
  persisted 
  in 
  the 
  tube, 
  no 
  matter 
  how 
  

   many 
  bridges 
  were 
  on 
  the 
  wires 
  or 
  where 
  placed. 
  This 
  was 
  

   found 
  due 
  to 
  the 
  oscillations 
  of 
  the 
  coil, 
  of 
  enormous 
  wave- 
  

   length, 
  and 
  relatively 
  gradual, 
  unreflected 
  by 
  any 
  form 
  of 
  

   bridge 
  used, 
  whereas 
  the 
  shorter 
  ones 
  due 
  to 
  the 
  sudden 
  oscil- 
  

   lations 
  across 
  S 
  are 
  cut 
  oft' 
  very 
  sharply. 
  With 
  practice 
  there 
  

   was 
  no 
  difficulty 
  in 
  distinguishing 
  the 
  different 
  characters 
  of 
  

   the 
  glow 
  produced 
  by 
  these 
  Efertzian 
  oscillations. 
  

  

  To 
  allow 
  of 
  work 
  in 
  daylight 
  this 
  vacuum 
  tube 
  was 
  completely 
  

   enclosed 
  in 
  a 
  light-tight 
  box, 
  and 
  viewed 
  through 
  a 
  slot 
  and 
  

  

  * 
  By 
  Drude's 
  metliod, 
  Wied. 
  Ann., 
  Iv, 
  p. 
  634. 
  

  

  