﻿"Fluting* 
  in 
  a 
  Sound- 
  Wave. 
  481 
  

  

  influence 
  the 
  forces 
  between 
  two 
  spheres, 
  a 
  cover-glass 
  was 
  

   mounted 
  on 
  the 
  end 
  of 
  a 
  glass 
  rod, 
  and 
  was 
  made 
  to 
  approach 
  

   the 
  spheres 
  from 
  below. 
  It 
  was 
  found 
  that 
  when 
  the 
  cover- 
  

   glass 
  was 
  very 
  close 
  to 
  the 
  spheres, 
  the 
  attraction 
  parallel 
  and 
  

   repulsion 
  transverse 
  to 
  the 
  stream-lines 
  was 
  increased. 
  

  

  IV. 
  Discussion 
  of 
  the 
  Data. 
  

  

  The 
  data 
  here 
  presented 
  have 
  experimentally 
  verified 
  the 
  

   presence 
  of 
  the 
  forces 
  deduced 
  from 
  the 
  theory 
  of 
  a 
  perfect 
  

   fluid, 
  and 
  make 
  manifest 
  other 
  forces. 
  The 
  presence 
  of 
  these 
  

   new 
  forces, 
  which 
  are 
  opposite 
  in 
  direction 
  to 
  the 
  perfect 
  

   fluid 
  forces, 
  were 
  indicated 
  in 
  the 
  experiments 
  with 
  different 
  

   gases, 
  but 
  in 
  the 
  observations 
  with 
  spheres 
  the 
  effect 
  of 
  these 
  

   forces 
  has 
  not 
  only 
  been 
  seen, 
  but 
  the 
  relative 
  magnitude 
  of 
  

   the 
  two 
  forces 
  has 
  been 
  roughly 
  measured, 
  so 
  that 
  the 
  function 
  

   of 
  the 
  distance 
  apart 
  of 
  the 
  spheres 
  varies 
  more 
  rapidly 
  than 
  

   the 
  perfect 
  fluid 
  function. 
  

  

  The 
  experiments 
  with 
  different 
  gases, 
  whose 
  coefficient 
  of 
  

   viscosity 
  varies, 
  the 
  increase 
  of 
  these 
  forces 
  on 
  the 
  approach 
  

   of 
  a 
  plane, 
  and 
  the 
  fact 
  that 
  they 
  are 
  opposite 
  in 
  direction 
  to 
  

   the 
  perfect 
  fluid 
  forces, 
  indicate 
  that 
  these 
  forces 
  are 
  due 
  

   to 
  internal 
  friction 
  or 
  viscosity 
  of 
  the 
  fluid 
  used 
  as 
  medium. 
  

  

  V. 
  Formation 
  of 
  Lamina'. 
  

  

  As 
  has 
  already 
  been 
  stated, 
  Koenig 
  considered 
  the 
  two 
  

   forces, 
  and 
  the 
  moment 
  deduced 
  from 
  the 
  theory 
  of 
  a 
  perfect 
  

   fluid, 
  sufficient 
  to 
  explain 
  the 
  formation 
  of 
  the 
  lamina) 
  pro- 
  

   duced 
  in 
  the 
  ventral 
  segment 
  of 
  a 
  Kundt's 
  resonance-tube. 
  

   If 
  no 
  other 
  than 
  the 
  attractive 
  force 
  existed 
  between 
  particles 
  

   whose 
  line 
  of 
  centres 
  is 
  perpendicular 
  to 
  the 
  stream-lines, 
  the 
  

   particles 
  would, 
  in 
  the 
  transverse 
  plane, 
  only 
  be 
  in 
  stable 
  

   equilibrium 
  when 
  they 
  are 
  in 
  actual 
  contact. 
  But 
  this 
  

   condition 
  is 
  not 
  in 
  accord 
  with 
  the 
  most 
  careful 
  observation 
  

   both 
  of 
  particles 
  and 
  spheres. 
  If, 
  however, 
  there 
  is 
  a 
  repulsive 
  

   force 
  which 
  is 
  only 
  effective 
  when 
  the 
  particles 
  are 
  not 
  more 
  

   than 
  one 
  half 
  their 
  diameter 
  apart, 
  there 
  will 
  be 
  a 
  position 
  in 
  

   the 
  transverse 
  plane 
  in 
  which 
  two 
  particles 
  are 
  in 
  stable 
  

   equilibrium, 
  and 
  this 
  position 
  is 
  the 
  position 
  in 
  which 
  the 
  

   particles 
  will 
  be 
  found 
  in 
  the 
  laminae. 
  

  

  And 
  if 
  in 
  the 
  direction 
  parallel 
  to 
  the 
  stream-lines 
  we 
  

   consider 
  only 
  a 
  repulsive 
  force, 
  all 
  particles 
  having 
  their 
  

   lines 
  of 
  centres 
  parallel 
  to 
  the 
  stream-lines 
  would 
  be 
  repelled 
  

   from 
  each 
  other 
  regardless 
  of 
  their 
  distance 
  apart 
  ; 
  but 
  this 
  

   does 
  not 
  agree 
  with 
  observation 
  for 
  particles 
  or 
  spheres 
  lying 
  

   within 
  about 
  *8 
  mm. 
  apart. 
  Particles 
  thus 
  situated 
  act 
  as 
  a 
  

  

  