﻿c 
  

  

  r 
  

  

  30 
  

  

  •819 
  

  

  45 
  

  

  •552 
  

  

  60 
  

  

  •355 
  

  

  90 
  

  

  •15 
  

  

  to 
  the 
  Measurement 
  of 
  Short 
  Electric 
  Waves. 
  259 
  

  

  intensity 
  at 
  right 
  angles 
  to 
  that 
  accounted 
  for 
  in 
  the 
  above 
  

   formula, 
  and 
  suggests 
  the 
  addition 
  of 
  a 
  term 
  -15sin 
  2 
  a. 
  

   If 
  this 
  is 
  done 
  we 
  have 
  

  

  Ij/Ig 
  = 
  cos 
  2 
  a 
  + 
  *15siir 
  a. 
  

  

  With 
  this 
  formula, 
  I 
  have 
  calculated 
  the 
  ratio 
  of 
  the 
  intensities 
  

   and 
  placed 
  them 
  in 
  the 
  third 
  column 
  of 
  the 
  following 
  table 
  for 
  

   comparison 
  with 
  the 
  ratio 
  of 
  the 
  deflections 
  : 
  

  

  a. 
  di/do 
  obs. 
  I1/I2 
  calc. 
  

  

  •;y 
  

   •575 
  

   •362 
  

   •15 
  

  

  It 
  is 
  seen 
  that 
  the 
  observed 
  values 
  agree 
  fairly 
  well 
  with 
  

   those 
  calculated 
  from 
  the 
  formula. 
  Though 
  the 
  experiment 
  is 
  

   not 
  conclusive, 
  it 
  seems 
  strongly 
  probably 
  that 
  the 
  deflections 
  

   of 
  the 
  receiving 
  instrument 
  are 
  proportional 
  to 
  the 
  intensity 
  of 
  

   the 
  waves. 
  

  

  The 
  wave-length 
  in 
  this 
  and 
  the 
  next 
  experiment 
  was 
  4*4 
  cm 
  , 
  

   measured 
  by 
  the 
  method 
  of 
  stationary 
  waves. 
  

  

  Transparency 
  of 
  Wood. 
  — 
  Mr. 
  JEfcighi 
  has 
  shown 
  that 
  certain 
  

   woods 
  transmit 
  waves 
  more 
  freely 
  when 
  the 
  grain 
  is 
  in 
  one 
  

   direction 
  with 
  respect 
  to 
  the 
  oscillator 
  than 
  when 
  it 
  is 
  in 
  the 
  

   perpendicular 
  direction. 
  Below 
  is 
  a 
  short 
  table 
  of 
  data 
  con- 
  

   firming 
  Mr. 
  Righi's 
  observation. 
  A 
  piece 
  of 
  pine 
  board 
  2^*4 
  

   centimeters 
  square 
  by 
  4*8 
  centimeters 
  thick 
  was 
  interposed 
  

   between 
  the 
  oscillator 
  and 
  the 
  resonator, 
  and 
  readings 
  were 
  

   taken 
  with 
  the 
  grain 
  perpendicular 
  to 
  the 
  direction 
  of 
  the 
  

   electric 
  oscillation, 
  with 
  the 
  grain 
  parallel 
  to 
  these 
  oscillations, 
  

   and 
  then 
  with 
  the 
  board 
  removed. 
  The 
  readings 
  are 
  in 
  milli- 
  

   meters, 
  and 
  the 
  dashes 
  indicate 
  the 
  order 
  of 
  taking 
  the 
  observa- 
  

   tions. 
  

  

  Out. 
  

  

  Grain 
  perp. 
  

  

  Grain 
  parallel. 
  

  

  

  1 
  "3 
  '4. 
  

  

  p.f| 
  

  

  154 
  

  

  12-8 
  

  

  u 
  

   7*9 
  

  

  15-8 
  

  

  12 
  # 
  2 
  

  

  7-0 
  

  

  17*1 
  

  

  122 
  

  

  7-0 
  

  

  15-0 
  

  

  12-0 
  

  

  6'5 
  

  

  14.5 
  

  

  10-5 
  

  

  6-9 
  

  

  14'2 
  

  

  10-0 
  

  

  7*1 
  

  

  14-2 
  

  

  

  

  15*2 
  

  

  11-9 
  

  

  7*2 
  means. 
  

  

  Percentage 
  transmitted 
  with 
  the 
  grain 
  perp. 
  is 
  78-3. 
  

   " 
  " 
  " 
  " 
  par. 
  is 
  47-4. 
  

  

  