﻿452 
  Prof. 
  0. 
  W. 
  Richardson 
  on 
  the 
  

  

  Whatever 
  the 
  value 
  "of 
  x, 
  the 
  smallest 
  negative 
  root 
  of 
  this 
  

   equation 
  lies 
  between 
  t=— 
  20 
  and 
  t=— 
  22 
  ; 
  so 
  that 
  

  

  at 
  i 
  = 
  \{0 
  — 
  t) 
  = 
  x 
  — 
  r 
  ; 
  

   i 
  e 
  ,r+ 
  9 
  

  

  h 
  = 
  mM> 
  = 
  10 
  ~ 
  3 
  sec 
  - 
  nearly 
  ' 
  

  

  if 
  w 
  is 
  not 
  greater 
  than 
  about 
  20 
  cm., 
  and 
  t 
  is 
  of 
  the 
  same 
  

   order. 
  

  

  It 
  is 
  evident 
  that 
  the 
  value 
  of 
  t 
  x 
  cannot 
  greatly 
  vary 
  with 
  x. 
  

   The 
  reason 
  for 
  the 
  appearance 
  of 
  x 
  in 
  this 
  equation 
  is 
  that 
  

   \{& 
  — 
  t) 
  was 
  treated 
  as 
  large 
  in 
  forming 
  the 
  approximate 
  

   values 
  of 
  x 
  and 
  t 
  in 
  equations 
  (17"). 
  

  

  The 
  result 
  t 
  l 
  = 
  10~' 
  6 
  lends 
  weight 
  to 
  the 
  hypothesis 
  that 
  a 
  

   very 
  shrill 
  note, 
  e. 
  g. 
  a 
  hiss, 
  is 
  not 
  propagated 
  in 
  the 
  same 
  

   manner 
  as 
  an 
  ordinary 
  sound-wave. 
  

  

  When 
  conductivity 
  of 
  heat 
  and 
  viscosity 
  are 
  taken 
  into 
  

   account, 
  it 
  has 
  been 
  shown 
  by 
  Gr. 
  I. 
  Taylor 
  * 
  that 
  the 
  motion 
  

   in 
  an 
  ordinary 
  sound-wave 
  does 
  not 
  become 
  discontinuous. 
  

   The 
  present 
  paper 
  is 
  to 
  be 
  taken 
  merely 
  as 
  an 
  attempt 
  to 
  

   follow 
  out 
  the 
  motion, 
  before 
  discontinuity 
  ensues, 
  on 
  the 
  

   assumption 
  that 
  equation 
  (1) 
  takes 
  account 
  of 
  all 
  the 
  facts. 
  

   With 
  what 
  happens 
  in 
  tlie 
  neighbourhood 
  of 
  a 
  discontinuity, 
  

   when 
  viscosity 
  and 
  conductivity 
  are 
  both 
  zero, 
  we 
  are 
  not 
  

   here 
  concerned, 
  and 
  the 
  problem 
  is 
  one 
  of 
  little 
  physical 
  

   importance, 
  though 
  from 
  a 
  purely 
  mathematical 
  point 
  of 
  

   view 
  it 
  possesses 
  a 
  certain 
  interest. 
  

  

  XXXV. 
  The 
  Ions 
  from 
  Hot 
  Salts. 
  By 
  0. 
  W. 
  RlCHABDSON, 
  

   M.A., 
  Jj.Sc.j 
  F.P.S., 
  Professor 
  of 
  Pltysics, 
  Princeton 
  

   University 
  j\ 
  

  

  J'l^HIS 
  paper 
  describes 
  the 
  results 
  of 
  experiments 
  which 
  

   A 
  form 
  a 
  continuation 
  of 
  earlier 
  work 
  carried 
  out 
  in 
  this 
  

   laboratory, 
  partly 
  by 
  the 
  writer 
  % 
  and 
  partly 
  by 
  Dr. 
  C. 
  

   J. 
  Davisson 
  §. 
  Some 
  of 
  the 
  main 
  points 
  have 
  already 
  been 
  

   briefly 
  indicated 
  ||. 
  The 
  chief 
  object 
  of 
  the 
  investigation 
  

   has 
  been 
  the 
  measurement 
  of 
  the 
  specific 
  charge 
  or 
  the 
  

   electric 
  molecular 
  weight 
  of 
  the 
  emitted 
  ions 
  ; 
  but 
  in 
  certain 
  

   cases 
  other 
  points 
  which 
  seemed 
  to 
  be 
  of 
  interest 
  or 
  importance 
  

  

  * 
  Proceeding's 
  of 
  the 
  Royal 
  Society, 
  A. 
  vol. 
  lxxxiv. 
  1910, 
  pp. 
  371-7. 
  

  

  t 
  Com 
  mimical 
  ed 
  bv 
  the 
  Author. 
  

  

  % 
  Phil. 
  Mag. 
  vol. 
  xx. 
  pp. 
  981, 
  999 
  (1910) 
  ; 
  vol. 
  xxii. 
  p. 
  6G9 
  ^1911). 
  

  

  § 
  Phil. 
  Mho-, 
  vol. 
  xxiii. 
  pp. 
  121, 
  139 
  (1912). 
  

  

  |i 
  Phys. 
  Rev. 
  vol. 
  xxxiv. 
  p. 
  386 
  (1912). 
  

  

  