﻿8 
  O. 
  V. 
  Maclean— 
  Velocity 
  of 
  Electric 
  Waves 
  in 
  Air. 
  

  

  Euhmkorff 
  coil, 
  tlie 
  nature 
  of 
  the 
  secondary 
  sparks 
  ehanse 
  so 
  

   mucli 
  that 
  the 
  readings 
  must 
  be 
  disregarded. 
  The 
  greatest 
  

   care 
  had 
  to 
  bo 
  exercised 
  to 
  preserve 
  the 
  equahty 
  of 
  the 
  oscil- 
  

   lator 
  sparks, 
  throughout 
  the 
  whole 
  of 
  the 
  measurements 
  

  

  It 
  was 
  further 
  noticed, 
  whenever 
  the 
  key 
  of 
  the 
  oscillator 
  

   circuit 
  was 
  closed 
  (the 
  coherer 
  key 
  being 
  first 
  closed), 
  there 
  

   was 
  always 
  a 
  very 
  distinct 
  increase 
  in 
  the 
  Mille-Ampere 
  meter 
  

   readings 
  even 
  before 
  the 
  sparking 
  at 
  the 
  oscillator 
  began 
  

   However, 
  as 
  soon 
  as 
  the 
  sparking 
  at 
  the 
  oscillator 
  commenced 
  

   this 
  increased 
  reading 
  was 
  augmented 
  more 
  or 
  less 
  according 
  

   to 
  the 
  distance 
  of 
  the 
  coherer 
  from 
  the 
  reflector. 
  This 
  necu 
  

   har 
  motion 
  of 
  the 
  needle 
  before 
  the 
  sparking 
  begins 
  at 
  the 
  

   oscillator 
  seems 
  to 
  point 
  to 
  an 
  electrostatic 
  effect 
  upon 
  the 
  

   coherer 
  globu 
  es, 
  due 
  to 
  electric 
  or 
  magnetic 
  causes 
  proeeedina 
  

   trom 
  the 
  oscillator 
  and 
  preceding 
  those 
  oscillations 
  which 
  giv? 
  

   rise 
  to 
  the 
  stationary 
  waves 
  ; 
  whatever 
  the 
  cause 
  may 
  be, 
  it 
  has 
  

   the 
  effect 
  of 
  lessening 
  the 
  resistance 
  between 
  tlie 
  coherer 
  

   globules. 
  This 
  phenomenon 
  would 
  appear 
  to 
  throw 
  some 
  light 
  

   pon 
  the 
  real 
  cause 
  of 
  the 
  action 
  of 
  a 
  coherer. 
  It 
  shows 
  that 
  

   the 
  nietal 
  particles 
  are 
  attracted 
  nearer 
  to 
  each 
  other 
  and 
  there 
  

   held 
  in 
  contact 
  by 
  the 
  electrostatic 
  effect 
  produced 
  upon 
  tliem 
  

   dfffpifnr'f?/* 
  the 
  electric 
  waves. 
  Such 
  an 
  effect 
  being 
  

   diffeient 
  at 
  differen 
  distances 
  from 
  the 
  reflector, 
  and 
  most 
  

   marked 
  near 
  the 
  oscillator, 
  would 
  very 
  much 
  alter 
  the 
  readings 
  

   as 
  really 
  given 
  by 
  the 
  wires 
  we 
  are 
  endeavoring 
  to 
  measure 
  

   Accordingly 
  this 
  effect 
  had 
  to 
  be 
  eliminated. 
  Tlfe 
  elimina 
  ion 
  

   7nd 
  T. 
  ^'^°°™fl'«''<^d 
  Upon 
  first 
  closing 
  the 
  coherer 
  circuit 
  

   and 
  a 
  lowing 
  the 
  needle 
  to 
  come 
  to 
  rest 
  and 
  then 
  closing 
  the 
  

   oscillator 
  circuit, 
  the 
  above 
  described 
  phenomenon 
  havino- 
  taken 
  

   place, 
  the 
  sparking 
  at 
  the 
  oscillator 
  was 
  continued 
  fo? 
  a 
  few 
  

   seconds 
  causing 
  the 
  needle 
  to 
  creep 
  up 
  to 
  a 
  maximum 
  reading, 
  

   llien 
  the 
  oscillator 
  circuit 
  was 
  opened 
  and 
  the 
  coherer 
  cirenU 
  

   was 
  opened 
  and 
  closed 
  four 
  or 
  five 
  times 
  in 
  succession 
  ; 
  each 
  

   reTdini"' 
  "f^ 
  ^.'•'^'"■■"ed 
  to 
  the 
  above 
  determined 
  maximum 
  

  

  o?rc, 
  'tin. 
  11 
  r. 
  ?'■■'''■ 
  ,°''"''"'' 
  ^^^ 
  °P''"«'' 
  tl'e 
  oscillator 
  

   c 
  rcmt 
  closed, 
  while 
  the 
  sparking 
  was 
  continued 
  for 
  some 
  time, 
  

   ad 
  finally 
  the 
  coherer 
  circuit 
  was 
  closed. 
  The 
  above 
  deter- 
  

   mined 
  maximum 
  reading 
  of 
  the 
  needle 
  is 
  in 
  all 
  cases 
  (except 
  

   ZlZ 
  "f 
  ,'r°'"^':'''' 
  '« 
  '1' 
  a 
  node) 
  augmented, 
  the 
  amount 
  of 
  this 
  

   augmenta 
  ion 
  increasing 
  or 
  decreasing 
  as 
  we 
  move 
  away 
  from 
  

   the 
  reflector 
  towards 
  the 
  oscillator. 
  It 
  is 
  only 
  such 
  waves 
  as 
  

   the 
  vigorous 
  and 
  prolonged 
  sparking 
  at 
  the 
  oscillator 
  sets 
  up 
  

   and 
  maintains 
  hat 
  are 
  able 
  to 
  increase 
  the 
  first 
  determined 
  

   maximum 
  reading 
  Thus 
  the 
  eftects 
  of 
  the 
  above 
  observed 
  

  

  t 
  if,Tr;' 
  "'■' 
  ° 
  ""''"' 
  ' 
  '"""' 
  *'"^.>' 
  '^'-^ 
  Po^verless 
  to 
  alter 
  

   2,ntf 
  i 
  '"f 
  "'"^"n»'" 
  '-eadins- 
  Such 
  a 
  precaution 
  

  

  demanded 
  a 
  great 
  amount 
  of 
  additional 
  time 
  and 
  patience 
  ; 
  

  

  