﻿Chemistry 
  and 
  Physics. 
  137 
  

  

  In 
  general, 
  the 
  reproductions 
  of 
  the 
  photographs 
  show 
  the 
  

   following 
  characteristics 
  of 
  the 
  air 
  column 
  within 
  the 
  liquid 
  

   and 
  above 
  the 
  descending 
  shot. 
  Immediately 
  after 
  the 
  sphere 
  

   has 
  entered 
  the 
  liquid 
  the 
  boundary 
  of 
  the 
  air 
  column 
  resembles 
  

   a 
  paraboloid 
  of 
  revolution 
  with 
  the 
  axis 
  vertical. 
  A 
  small 
  frac- 
  

   tion 
  of 
  a 
  second 
  later 
  the 
  elongated 
  column 
  begins 
  to 
  contract 
  

   in 
  horizontal 
  cross-section 
  at 
  a 
  short 
  distance 
  above 
  the 
  top 
  of 
  the 
  

   shot. 
  As 
  the 
  depth 
  of 
  the 
  shot 
  increases 
  this 
  contraction 
  con- 
  

   tinues, 
  thus 
  causing 
  the 
  vertical 
  plane 
  section 
  of 
  the 
  trailing 
  air 
  

   column 
  to 
  roughly 
  resemble 
  an 
  elongated 
  viscous 
  droplet 
  sus- 
  

   pended 
  from 
  the 
  apex 
  of 
  a 
  fluted 
  inverted 
  cone, 
  the 
  base 
  of 
  

   which 
  coincides 
  with 
  the 
  free 
  surface 
  of 
  the 
  liquid. 
  Next 
  the 
  

   air 
  column 
  is 
  severed, 
  leaving 
  opposing 
  points 
  oil 
  the 
  inverted 
  

   cone 
  and 
  on 
  the 
  fish-shaped 
  air 
  recess 
  which 
  has 
  the 
  shot 
  at 
  its 
  

   lower 
  or 
  head 
  end. 
  Finally 
  the 
  tail 
  of 
  this 
  recess 
  contracts 
  and, 
  

   at 
  the 
  same 
  time, 
  rings 
  or 
  flutings 
  appear 
  just 
  above 
  the 
  shot. 
  

   Simultaneously 
  the 
  cone 
  shrinks 
  toward 
  the 
  free 
  surface 
  of 
  the 
  

   liquid 
  and 
  becomes 
  lumpy 
  near 
  the 
  vertex. 
  The 
  configurations 
  

   assumed 
  by 
  the 
  liquid 
  at, 
  and 
  above, 
  its 
  free 
  surface 
  are 
  similar 
  

   to 
  the 
  ones 
  photographed 
  by 
  A. 
  M. 
  Worthington 
  and 
  beautifully 
  

   illustrated 
  both 
  in 
  the 
  ''Phil. 
  Trans." 
  (1897) 
  and 
  in 
  his 
  fasci- 
  

   nating 
  little 
  book 
  entitled 
  "The 
  Splash 
  of 
  a 
  Drop." 
  

  

  With 
  regard 
  to 
  the 
  acoustical 
  aspect 
  of 
  the 
  problem 
  the 
  fol- 
  

   lowing 
  quotation 
  from 
  the 
  original 
  paper 
  will 
  be 
  sufficient. 
  ' 
  ' 
  The 
  

   note 
  which 
  a 
  cavity 
  of 
  continually 
  varying 
  volume 
  would 
  give 
  

   when 
  acting 
  as 
  a 
  resonator 
  would 
  have 
  its 
  gravest 
  pitch 
  just 
  

   before 
  the 
  sides 
  coalesce. 
  The 
  predominant 
  pitch 
  would 
  be 
  of 
  

   the 
  same 
  order 
  as, 
  but 
  lower 
  than, 
  that 
  of 
  an 
  open 
  pipe 
  of 
  the 
  

   length 
  of 
  the 
  cavity, 
  that 
  is, 
  the 
  predominant 
  wave-length 
  would 
  

   be 
  more 
  than 
  four 
  times 
  the 
  depth 
  of 
  the 
  cavity. 
  The 
  larger 
  of 
  

   the 
  two 
  sizes 
  of 
  shot 
  used 
  in 
  the 
  experiments, 
  when 
  striking 
  with 
  

   a 
  velocity 
  of 
  16 
  feet 
  per 
  second, 
  sometimes 
  left 
  an 
  open 
  cavity 
  

   more 
  than 
  4 
  inches 
  deep 
  ; 
  this 
  would 
  make 
  the 
  predominant 
  

   wave-length 
  about 
  1-5 
  feet, 
  but 
  only 
  a 
  few 
  (3 
  or 
  4) 
  vibrations 
  of 
  

   this 
  length 
  would 
  have 
  time 
  to 
  be 
  formed, 
  so 
  that, 
  incidentally, 
  

   the 
  present 
  experiments 
  show 
  what 
  a 
  small 
  number 
  of 
  vibrations 
  

   can 
  give 
  rise 
  to 
  the 
  sensation 
  of 
  pitch. 
  ' 
  ' 
  It 
  should 
  be 
  remarked, 
  

   in 
  conclusion, 
  that 
  the 
  paper 
  contains 
  the 
  elementary 
  quantita- 
  

   tive 
  theory 
  of 
  the 
  formation 
  of 
  the 
  air 
  column 
  and 
  an 
  approxi- 
  

   mate 
  equation 
  of 
  the 
  plane 
  generating 
  curve 
  of 
  the 
  aqueous 
  

   envelope 
  of 
  the 
  cavity. 
  Proc. 
  Boy. 
  Soc., 
  95 
  A, 
  138, 
  1918. 
  

  

  h. 
  s. 
  u. 
  

  

  7. 
  Polarization 
  and 
  Intensity 
  of 
  Light 
  Scattered 
  hy 
  Gases. 
  — 
  

   The 
  present 
  paper 
  by 
  R. 
  J. 
  Strutt 
  gives 
  a 
  detailed 
  account 
  of 
  

   his 
  second 
  series 
  of 
  experiments 
  on 
  the 
  scattering 
  of 
  light 
  by 
  the 
  

   molecules 
  of 
  gases 
  and 
  vapors. 
  The 
  most 
  important 
  results 
  

   obtained 
  may 
  be 
  briefly 
  summarized 
  in 
  the 
  following 
  sentences. 
  

  

  The 
  light 
  scattered 
  at 
  right 
  angles 
  to 
  the 
  axis 
  of 
  the 
  primary 
  

   beam 
  by 
  gases 
  and 
  vapors 
  is 
  not 
  completely 
  polarized. 
  The 
  

  

  