﻿484 
  Mr. 
  B. 
  S. 
  Cohen 
  on 
  Production 
  of 
  Small 
  

  

  in 
  the 
  make 
  contact 
  position 
  connects 
  a 
  battery 
  to 
  a 
  capacity 
  

   in 
  parallel 
  with 
  an 
  inductance 
  and 
  transformer 
  primary. 
  

  

  On 
  the 
  break 
  between 
  the 
  cap 
  and 
  contact 
  an 
  oscillation 
  

   occurs 
  in 
  the 
  circuit. 
  

  

  By 
  this 
  method 
  a 
  series 
  of 
  damped 
  trains 
  of 
  oscillations 
  o£ 
  

   any 
  frequency 
  can 
  be 
  produced, 
  the 
  trains 
  following 
  each 
  

   other 
  with 
  the 
  frequency 
  of 
  the 
  wire 
  vibrations. 
  

  

  Theory 
  of 
  Action. 
  — 
  Oscillations 
  will 
  occur 
  whe 
  n 
  jj 
  \^ 
  3 
  

  

  1 
  f~\ 
  IP 
  - 
  

   their 
  frequency 
  being 
  given 
  by 
  ~- 
  \f 
  j^. 
  — 
  7-^2 
  ' 
  With 
  the 
  

  

  values 
  of 
  L/ 
  K 
  and 
  B, 
  used, 
  the 
  last 
  term 
  can 
  be 
  neglected 
  and 
  

  

  i 
  rr~ 
  

  

  ttV 
  LK' 
  

  

  formula 
  becomes 
  n 
  

   Air 
  

  

  The 
  total 
  output 
  in 
  watts, 
  excluding 
  all 
  losses, 
  will 
  be 
  the 
  

   energy 
  stored, 
  divided 
  by 
  the 
  interval 
  of 
  time 
  between 
  each 
  

   succeeding 
  train 
  of 
  waves. 
  

  

  The 
  equation 
  to 
  the 
  line 
  joining 
  the 
  peaks 
  of 
  the 
  damped 
  

  

  waves 
  is 
  Y 
  = 
  e 
  2L 
  , 
  so 
  that 
  for 
  small 
  damping 
  L 
  must 
  be 
  

   large 
  and 
  R, 
  small, 
  which 
  also 
  gives 
  the 
  maximum 
  output. 
  

  

  In 
  one 
  of 
  the 
  circuits 
  used 
  the 
  inductance 
  is 
  '037 
  henry, 
  

   and 
  its 
  effective 
  resistance 
  which 
  is 
  practically 
  invariable 
  

   over 
  the 
  range 
  of 
  frequency 
  used 
  is 
  10 
  ohms. 
  (These 
  figures 
  

   include 
  the 
  resistance 
  and 
  inductance 
  of 
  the 
  primary 
  of 
  

   transformer.) 
  

  

  Fig. 
  7 
  (PI. 
  XVII.) 
  shows 
  an 
  oscillogram 
  of 
  damped 
  wave 
  

   trains 
  produced 
  in 
  the 
  manner 
  just 
  described. 
  

  

  The 
  three 
  frequencies 
  are 
  490~, 
  959~, 
  and 
  2880^- 
  pro- 
  

   duced 
  by 
  using 
  the 
  three 
  capacities, 
  2*88 
  mfd, 
  *8 
  mfd, 
  and 
  

   *1 
  mfd 
  respectively. 
  

  

  The 
  frequency 
  of 
  the 
  vibrating 
  wire 
  was 
  90^ 
  in 
  all 
  three 
  

   cases. 
  It 
  will 
  be 
  observed 
  that 
  only 
  part 
  of 
  a 
  complete 
  train 
  

   is 
  utilized 
  in 
  the 
  lower 
  frequency 
  waves. 
  

  

  Problem 
  of 
  Output. 
  — 
  The 
  transformer 
  used 
  in 
  this 
  circuit 
  

   is 
  a 
  small 
  one 
  of 
  the 
  telephone 
  type, 
  with 
  a 
  few 
  turns 
  and 
  a 
  

   somewhat 
  loose 
  coupling. 
  By 
  reason 
  of 
  this, 
  variations 
  in 
  

   the 
  frequency 
  and 
  damping 
  of 
  the 
  output 
  caused 
  by 
  variations 
  

   of 
  the 
  load 
  on 
  the 
  secondary 
  affecting 
  the 
  effective 
  self- 
  

   induction 
  of 
  the 
  oscillating 
  circuit 
  are 
  rendered 
  small, 
  but 
  at 
  

   the 
  same 
  time 
  the 
  output 
  is 
  reduced. 
  

  

  In 
  cases 
  where 
  the 
  load 
  is 
  constant 
  it 
  is 
  possible 
  to 
  use 
  a 
  

   more 
  efficient 
  transformer 
  and 
  so 
  obtain 
  a 
  considerable 
  increase 
  

   in 
  the 
  output. 
  

  

  It 
  is 
  worthy 
  of 
  mention 
  that 
  in 
  the 
  apparatus 
  as 
  constructed, 
  

   the 
  chief 
  storage 
  of 
  energy 
  occurs 
  in 
  the 
  coil 
  and 
  not 
  in 
  the 
  

  

  