﻿Trowbridge 
  and 
  Duane 
  — 
  Velocity 
  of 
  Electric 
  Waves. 
  299 
  

  

  would 
  meet 
  at 
  the 
  point 
  G 
  one 
  of 
  negative 
  electricity 
  that 
  had 
  

   previously 
  started 
  from 
  F 
  and 
  traveled 
  around 
  F 
  H 
  JG, 
  

   another 
  at 
  the 
  point 
  J, 
  and 
  still 
  another 
  at 
  the 
  point 
  H. 
  Sta- 
  

   tionary 
  vibrations 
  in 
  the 
  circuit 
  EG 
  JKF 
  were 
  thus 
  set 
  up 
  

   with 
  nodes 
  at 
  the 
  points 
  G, 
  J 
  and 
  H, 
  and 
  ventral 
  segments 
  

   halfway 
  between 
  them 
  at 
  K 
  and 
  L. 
  The 
  method 
  of 
  dis- 
  

   covering 
  when 
  the 
  circuits 
  were 
  in 
  tune, 
  and 
  of 
  investigating 
  

   the 
  shape 
  of 
  the 
  waves 
  will 
  be 
  described 
  later. 
  The 
  point 
  to 
  

   be 
  noticed 
  here 
  is 
  that 
  the 
  vibrations 
  were 
  sufficiently 
  power- 
  

   ful 
  to 
  cause 
  a 
  luminous 
  discharge 
  on 
  the 
  surface 
  of 
  the 
  wire 
  at 
  

   points 
  where 
  the 
  accumulation 
  of 
  electricity 
  was 
  a 
  maximum, 
  

   i. 
  e. 
  at 
  K 
  and 
  L, 
  while 
  at 
  the 
  nodal 
  points 
  G, 
  J 
  and 
  H 
  the 
  wire 
  

   was 
  entirely 
  dark. 
  Still 
  further 
  the 
  wave 
  formation 
  could 
  be 
  

   made 
  apparent 
  to 
  the 
  sense 
  of 
  hearing 
  as 
  well 
  as 
  that 
  of 
  sight 
  ; 
  

   for 
  placing 
  the 
  ear 
  within 
  a 
  few 
  centimeters 
  of 
  the 
  wire 
  and 
  

   walking 
  along 
  it, 
  a 
  distinct 
  crackling 
  sound 
  could 
  be 
  heard 
  at 
  

   the 
  points 
  K 
  and 
  L 
  whereas 
  no 
  such 
  sound 
  could 
  be 
  heard 
  at 
  

   G, 
  J 
  and 
  H. 
  By 
  placing 
  bits 
  of 
  glass 
  tubing 
  on 
  the 
  wire 
  the 
  

   sound 
  was 
  much 
  intensified 
  at 
  the 
  points 
  K 
  and 
  L, 
  and 
  the 
  

   phenomena 
  made 
  more 
  striking. 
  It 
  might 
  be 
  supposed 
  that 
  

   by 
  decreasing 
  the 
  capacity 
  of 
  the 
  primary 
  condenser, 
  and 
  there- 
  

   fore 
  the 
  period 
  of 
  its 
  oscillation, 
  the 
  secondary 
  circuit 
  could 
  

   be 
  broken 
  up 
  into 
  a 
  new 
  set 
  of 
  shorter 
  stationary 
  waves, 
  with 
  

   nodes 
  at 
  J 
  and 
  at 
  points 
  somewhere 
  near 
  K, 
  L, 
  G 
  and 
  H, 
  and 
  

   ventral 
  segments 
  between 
  them. 
  This 
  we 
  tried 
  with 
  perfect 
  

   success 
  except 
  that 
  it 
  was 
  not 
  possible 
  to 
  cause 
  the 
  light 
  at 
  K 
  

   and 
  L 
  to 
  actually 
  disappear. 
  There 
  was 
  decidedly 
  less 
  light 
  at 
  

   these 
  points 
  however 
  than 
  on 
  either 
  side 
  of 
  them. 
  The 
  light 
  

   of 
  course 
  is 
  simply 
  that 
  which 
  always 
  appears 
  around 
  wires 
  

   carrying 
  very 
  high 
  potential 
  currents, 
  the 
  interesting 
  point 
  

   being 
  that 
  it 
  appears 
  in 
  some 
  places 
  on 
  the 
  circuit 
  and 
  not 
  in 
  

   others. 
  The 
  experiment 
  showing 
  how 
  the 
  circuit 
  breaks 
  up 
  in 
  

   several 
  different 
  ways 
  would 
  form 
  a 
  most 
  beautiful 
  lecture 
  

   experiment. 
  

  

  As 
  a 
  means 
  of 
  ascertaining 
  when 
  the 
  circuits 
  were 
  in 
  reso- 
  

   nance, 
  and 
  of 
  investigating 
  the 
  form 
  of 
  the 
  wave 
  in 
  the 
  second- 
  

   ary 
  circuit 
  a 
  bolometer 
  similar 
  to 
  that 
  designed 
  by 
  Paalzow 
  and 
  

   Rubens* 
  was 
  used. 
  The 
  bolometer 
  was 
  used 
  in 
  this 
  present 
  

   investigation 
  to 
  detect 
  electrical 
  disturbances 
  in 
  a 
  conductor 
  

   and 
  to 
  measure 
  their 
  magnitudes 
  ; 
  but 
  it 
  did 
  not 
  indicate 
  either 
  

   the 
  direction 
  or 
  sign 
  of 
  the 
  quantities 
  measured. 
  Its 
  use 
  for 
  

   this 
  purpose 
  is 
  described 
  in 
  the 
  paper 
  of 
  Mr. 
  St. 
  John 
  already 
  

   referred 
  to. 
  

  

  The 
  conductors 
  that 
  were 
  electrically 
  connected 
  to 
  the 
  arm 
  

   of 
  the 
  bridge, 
  and 
  that 
  were 
  brought 
  near 
  the 
  circuit 
  consisted 
  

  

  * 
  Anwendung 
  des 
  bolometrischen 
  Princips 
  auf 
  Electrische 
  Messungen, 
  Wied. 
  

   Ann., 
  xxxvii, 
  529. 
  

  

  