﻿2 
  G. 
  V. 
  Maclean 
  — 
  Velocity 
  of 
  Electric 
  Waves 
  in 
  Air. 
  

  

  Poincare^ 
  and 
  Bjerknes,f 
  independent 
  of 
  each 
  other, 
  con- 
  

   tended 
  that 
  the 
  oscillator 
  and 
  resonator 
  each 
  set 
  up 
  their 
  own 
  

   vibrations, 
  which 
  are 
  not 
  necessarily 
  related, 
  and 
  that 
  the 
  varia- 
  

   tion 
  of 
  the 
  wave-length, 
  when 
  different 
  resonators 
  are 
  used 
  

   with 
  the 
  same 
  oscillator, 
  is 
  not 
  due 
  alone 
  to 
  multiple 
  resonance, 
  

   as 
  stated 
  by 
  Sarasin 
  and 
  de 
  la 
  Rive, 
  but 
  to 
  the 
  unequal 
  rate 
  of 
  

   damping 
  of 
  the 
  waves 
  by 
  the 
  resonator 
  and 
  oscillator. 
  If 
  the 
  

   rate 
  of 
  damping 
  in 
  the 
  resonator 
  is 
  small 
  in 
  comparison 
  with 
  

   that 
  of 
  the 
  oscillator, 
  then 
  Sarasin 
  and 
  de 
  la 
  Hive's 
  theory 
  

   holds 
  ; 
  if, 
  however, 
  the 
  rate 
  of 
  damping 
  of 
  the 
  resonator 
  is 
  great 
  

   in 
  comparison 
  with 
  that 
  of 
  the 
  oscillator, 
  Sarasin 
  and 
  de 
  la 
  

   Rive's 
  theory 
  fails. 
  The 
  length 
  of 
  the 
  internode 
  does 
  not 
  

   alter 
  when 
  the 
  same 
  oscillator 
  is 
  used 
  with 
  resonators 
  of 
  differ- 
  

   ent 
  sizes, 
  but 
  it 
  varies 
  with 
  the 
  dimensions 
  of 
  the 
  oscillator 
  

   when 
  the 
  same 
  resonator 
  is 
  employed 
  ; 
  the 
  wave-length 
  being 
  

   the 
  same 
  as 
  is 
  found 
  when 
  a 
  method 
  is 
  employed 
  in 
  which 
  no 
  

   resonator 
  is 
  needed. 
  " 
  If 
  the 
  rates 
  of 
  damping 
  of 
  the 
  oscilla- 
  

   tor 
  and 
  resonator 
  are 
  almost 
  the 
  same, 
  the 
  lengths 
  of 
  the 
  

   waves 
  they 
  produce 
  exercise 
  the 
  same 
  influence 
  upon 
  the 
  

   length 
  of 
  the 
  internode 
  measured." 
  

  

  Sarasin 
  and 
  de 
  la 
  Hive 
  had 
  also 
  pointed 
  out 
  the 
  necessity 
  of 
  

   having 
  the 
  oscillator 
  and 
  resonator 
  in 
  tune 
  with 
  each 
  other, 
  

   and 
  more 
  particularly 
  so 
  was 
  this 
  needful 
  when 
  the 
  waves 
  in 
  

   air 
  without 
  wires 
  were 
  measured. 
  

  

  In 
  the 
  experiment 
  about 
  to 
  be 
  described, 
  a 
  new 
  method 
  

   was 
  employed 
  by 
  which 
  the 
  direct 
  determination 
  of 
  the 
  period 
  

   of 
  the 
  oscillator 
  was 
  found. 
  The 
  oscillator 
  and 
  resonator 
  were 
  

   tuned 
  by 
  using 
  a 
  special 
  form 
  of 
  self-induction 
  and 
  capacity 
  

   and 
  balancing 
  them. 
  The 
  resonators 
  used 
  by 
  Hertz, 
  and 
  by 
  

   the 
  other 
  physicists 
  to 
  whom 
  reference 
  alone 
  has 
  been 
  made, 
  

   were 
  simple 
  loops 
  of 
  copper 
  wire 
  which 
  acted 
  as 
  the 
  self- 
  

   induction, 
  while 
  the 
  capacity 
  was 
  two 
  small 
  metal 
  spheres. 
  

   The 
  oscillators 
  had 
  very 
  large 
  capacities 
  in 
  comparison 
  with 
  

   those 
  of 
  the 
  resonators. 
  

  

  In 
  our 
  experiment 
  the 
  form 
  and 
  size 
  of 
  oscillator 
  and 
  resona- 
  

   tor, 
  as 
  also 
  the 
  dimensions 
  of 
  their 
  self-inductions 
  and 
  capacities, 
  

   are 
  identical. 
  The 
  resonator 
  here 
  used 
  is 
  a 
  specially 
  devised 
  

   coherer. 
  Many 
  attempts 
  of 
  late 
  have 
  been 
  made 
  to 
  success- 
  

   fully 
  employ 
  the 
  coherer 
  to 
  measure 
  electric 
  waves. 
  The 
  

   results 
  have 
  generally 
  been 
  to 
  stamp 
  the 
  coherer 
  as 
  an 
  instru- 
  

   ment 
  too 
  capricious 
  for 
  such 
  work. 
  In 
  this 
  connection 
  may 
  

   be 
  mentioned 
  the 
  work 
  of 
  Professor 
  Murani.;}: 
  He 
  used 
  a 
  

  

  * 
  Poincare, 
  Elektricitat 
  und 
  Optik, 
  1891. 
  Archives 
  des 
  sc. 
  pliys. 
  et 
  nat, 
  xxv, 
  

   p. 
  609, 
  1891. 
  

  

  f 
  Bjerknes, 
  Wiedemann's 
  Annalen. 
  Baud 
  xliv, 
  p. 
  75, 
  1891. 
  

  

  \ 
  Studio 
  della 
  onde 
  stazionarie 
  di 
  Hertz 
  col 
  mezzo 
  di 
  un 
  coherer, 
  del 
  Prof. 
  0. 
  

   Murani 
  del 
  R. 
  Istituto 
  Lombardo. 
  Milano, 
  1898. 
  

  

  