﻿62 
  

  

  Mr. 
  W. 
  Gr. 
  Hormell 
  on 
  the 
  

  

  experiments 
  have 
  shown 
  that 
  if 
  the 
  column 
  be 
  as 
  much 
  as 
  

   1*5 
  cm. 
  too 
  long 
  or 
  too 
  short, 
  the 
  position 
  of 
  the 
  fourth 
  node 
  

   is 
  not 
  affected. 
  The 
  conclusion, 
  therefore, 
  is 
  that 
  no 
  error 
  

   will 
  be 
  made 
  if 
  the 
  column 
  of 
  paraffin 
  be 
  1*5 
  cm. 
  too 
  long 
  or 
  

   too 
  short, 
  or 
  the 
  end 
  be 
  not 
  against 
  the 
  first 
  bridge. 
  This 
  

   fact 
  makes 
  it 
  very 
  convenient 
  when 
  using 
  the 
  same 
  column 
  

   for 
  different 
  wave-lengths. 
  

  

  This 
  same 
  column 
  of 
  proper 
  length 
  may 
  be 
  used 
  to 
  answer 
  

   the 
  second 
  question. 
  After 
  the 
  position 
  of 
  the 
  fourth 
  node 
  

   has 
  been 
  determined, 
  the 
  column 
  may 
  be 
  removed, 
  and 
  by 
  

   means 
  of 
  the 
  table-saw 
  the 
  section 
  reduced 
  to 
  one 
  6x8 
  cm. 
  

   The 
  process 
  of 
  locating 
  the 
  node 
  and 
  reducing 
  the 
  section 
  

   may 
  be 
  continued 
  until 
  the 
  column 
  is 
  too 
  thin 
  to 
  allow 
  further 
  

   reduction. 
  

  

  Table 
  IV. 
  shows 
  the 
  result 
  of 
  this 
  experiment. 
  From 
  it 
  we 
  

   learn 
  that 
  the 
  effective 
  field, 
  as 
  far 
  as 
  it 
  can 
  be 
  determined 
  by 
  

   means 
  of 
  an 
  argon 
  tube, 
  certainly 
  lies 
  within 
  a 
  column 
  whose 
  

   cross 
  section 
  is 
  5 
  x 
  7 
  cm. 
  By 
  a 
  comparison 
  of 
  the 
  values 
  in 
  

   the 
  fifth 
  column 
  with 
  those 
  in 
  the 
  first, 
  we 
  find 
  that 
  the 
  effect 
  

   on 
  the 
  half-wave 
  varies 
  approximately 
  inversely 
  as 
  the 
  square 
  

   of 
  the 
  distance 
  of 
  the 
  wires 
  from 
  the 
  outer 
  surface. 
  

  

  Table 
  IV. 
  

  

  Size 
  of 
  

   Column. 
  

  

  Area 
  of 
  

   Cross-section. 
  

  

  Position 
  of 
  

   Node. 
  

  

  Change 
  in 
  

  

  Position 
  of 
  

  

  Node. 
  

  

  Effect 
  on 
  

   one-half 
  

  

  Wave-length. 
  

  

  em. 
  

  

  sq. 
  cm. 
  

  

  cm. 
  

  

  cm. 
  

  

  cm. 
  

  

  7X8 
  

  

  56 
  

  

  120-34 
  

  

  

  

  6X8 
  

  

  48 
  

  

  120-20 
  

  

  

  

  5x7 
  

  

  35 
  

  

  12035 
  

  

  

  

  4x6 
  

  

  24 
  

  

  120-28 
  

  

  

  

  3X5 
  

  

  15 
  

  

  120-83 
  

  

  "5 
  

  

  •2 
  

  

  2x4 
  

  

  8 
  

  

  123-60 
  

  

  3-2 
  

  

  1-1 
  

  

  1-5x3-5 
  

  

  5-2 
  

  

  126-68 
  

  

  6-4 
  

  

  2-3 
  

  

  1x3 
  

  

  3 
  

  

  131-14 
  

  

  11-8 
  

  

  4-4 
  

  

  Four 
  specimens 
  of 
  the 
  paraffin 
  were 
  secured 
  from 
  a 
  

   wholesale 
  dealer. 
  They 
  were 
  known 
  as 
  numbers 
  120, 
  125, 
  

   130, 
  and 
  135, 
  their 
  numbers 
  representing 
  their 
  melting-point 
  

   on 
  the 
  Fahrenheit 
  scale. 
  Two 
  columns 
  of 
  each 
  kind 
  were 
  

   prepared, 
  and 
  the 
  melting-point 
  on 
  the 
  Centigrade 
  scale 
  noted. 
  

   The 
  density 
  was 
  determined 
  from 
  four 
  different 
  specimens 
  of 
  

   each 
  column. 
  The 
  total 
  pressure 
  to 
  which 
  the 
  paraffin 
  was 
  

   subjected 
  when 
  in 
  the 
  mould 
  was 
  2140 
  lbs., 
  or 
  7 
  lbs. 
  per 
  sq, 
  in. 
  

   Moulding 
  the 
  columns 
  under 
  pressure 
  was 
  the 
  only 
  way 
  in 
  

   which 
  masses 
  of 
  this 
  size 
  could 
  be 
  secured 
  of 
  anything 
  like 
  

  

  