﻿Directive 
  System 
  of 
  Wireless 
  Telegraphy. 
  639 
  

  

  arrangements, 
  as 
  well 
  as 
  supplying 
  the 
  necessary 
  informa- 
  

   tion 
  to 
  those 
  who 
  are 
  not 
  familiar 
  with 
  the 
  earlier 
  work, 
  

   which 
  has 
  been 
  fully 
  dealt 
  with 
  elsewhere*. 
  

  

  Part 
  I. 
  

  

  The 
  aerial 
  of 
  the 
  bilateral 
  system 
  is 
  composed 
  of 
  vertical 
  

   closed 
  oscillatory 
  circuits. 
  

  

  The 
  closed 
  oscillatory 
  circuit 
  is, 
  as 
  is 
  known, 
  an 
  oscillatory 
  

   circuit, 
  the 
  metallic 
  portion 
  of 
  which 
  forms 
  a 
  geometrically 
  

   " 
  nearly 
  closed 
  " 
  figure, 
  the 
  electric 
  field 
  of 
  which 
  is 
  concen- 
  

   trated 
  in 
  a 
  very 
  narrow 
  region, 
  and 
  the 
  conditions 
  of 
  

   vibration 
  of 
  which 
  are 
  independent 
  of 
  the 
  position 
  of 
  the 
  

   spark. 
  

  

  Although 
  in 
  such 
  circuits 
  the 
  electric 
  field 
  is 
  situate 
  almost 
  

   exclusively 
  between 
  the 
  armatures 
  of 
  the 
  condenser, 
  none 
  

   the 
  less 
  there 
  always 
  exists 
  an 
  electric 
  field 
  of 
  dispersion 
  

   the 
  lines 
  of 
  force 
  of 
  which 
  go 
  from 
  different 
  points 
  of 
  the 
  

   circuit 
  to 
  neighbouring 
  conductors 
  and 
  to 
  earth. 
  Conse- 
  

   quently, 
  if 
  one 
  of 
  these 
  circuits 
  be 
  vertically 
  placed 
  in 
  

   proximity 
  to 
  the 
  ground, 
  and 
  with 
  the 
  condenser 
  at 
  the 
  

   upper 
  part, 
  a 
  number 
  of 
  lines 
  of 
  force 
  will 
  reach 
  the 
  earth, 
  

   giving 
  rise 
  to 
  an 
  electromagnetic 
  field 
  which 
  propagates 
  

   itself 
  in 
  space. 
  Since 
  one 
  of 
  the 
  armatures 
  of 
  the 
  condenser 
  

   has 
  at 
  the 
  same 
  instant 
  an 
  equal 
  potential 
  of 
  opposite 
  sign 
  to 
  

   that 
  of 
  the 
  other, 
  the 
  electromagnetic 
  field 
  of 
  one 
  side 
  will 
  

   be 
  opposed 
  in 
  phase 
  relative 
  to 
  the 
  field 
  of 
  the 
  other 
  side. 
  

   As 
  a 
  result 
  it 
  is 
  evident 
  that 
  in 
  the 
  direction 
  perpendicular 
  

   to 
  the 
  plane 
  of 
  the 
  circuit 
  there 
  is 
  no 
  radiation 
  whatever 
  ; 
  

   that 
  is 
  to 
  say, 
  the 
  said 
  type 
  of 
  circuit 
  radiates 
  principally 
  in 
  

   its 
  own 
  plane. 
  

  

  An 
  oscillatory 
  circuit 
  placed 
  in 
  an 
  electromagnetic 
  field 
  

   will 
  become 
  the 
  seat 
  of 
  an 
  E.M.F. 
  due 
  to 
  the 
  variation 
  of 
  

   magnetic 
  flux 
  across 
  the 
  surface 
  bounded 
  by 
  the 
  circuit. 
  

   This 
  E.M.F. 
  will 
  vary 
  with 
  the 
  cosine 
  of 
  the 
  angle 
  which 
  

   the 
  plane 
  of 
  the 
  circuit 
  makes 
  with 
  the 
  direction 
  of 
  propa- 
  

   gation 
  of 
  the 
  field. 
  

  

  Using 
  the 
  Duddell 
  thermogalvanometer, 
  the 
  authors 
  have 
  

   determined 
  the 
  diagrams 
  of 
  the 
  energy 
  emitted 
  or 
  received 
  

   by 
  such 
  a 
  circuit. 
  The 
  energy 
  diagrams 
  obtained 
  were 
  

  

  * 
  Electrical 
  Engineering, 
  ii. 
  pp. 
  771-775 
  (1907), 
  and 
  iii. 
  pp. 
  348-351 
  

   (1908). 
  The 
  blocks 
  referring 
  to 
  this 
  part 
  of 
  the 
  paper 
  have 
  been 
  kindly 
  

   lent 
  by 
  the 
  Kilowatt 
  Publishing 
  Company. 
  

  

  