﻿148 
  Scientific 
  Intelligence. 
  

  

  11. 
  Velocity 
  and 
  susceptibility 
  to 
  magnetic 
  action 
  of 
  the 
  Cathode 
  

   rays. 
  — 
  In 
  the 
  same 
  field 
  which 
  Professor 
  J. 
  J. 
  Thomson 
  has 
  

   worked,* 
  E. 
  Wiechert 
  has 
  made 
  an 
  elaborate 
  investigation 
  and 
  

   believes 
  that 
  the 
  discoveries 
  of 
  Lenard 
  and 
  Rontgen 
  show 
  the 
  

   existence 
  of 
  an 
  electrical 
  atom 
  of 
  smaller 
  dimensions 
  than 
  the 
  

   chemical 
  atom. 
  This 
  electrical 
  atom 
  has 
  a 
  negative 
  charge. 
  It 
  

   is 
  reasonable 
  to 
  suppose 
  also 
  that 
  there 
  are 
  positive 
  atoms 
  of 
  cor- 
  

   responding 
  size. 
  The 
  deviation 
  of 
  the 
  cathode 
  rays 
  by 
  magnetic 
  

   influence 
  seems 
  to 
  the 
  author 
  far 
  greater 
  than 
  if 
  they 
  consisted 
  of 
  

   streams 
  of 
  ordinary 
  chemical 
  atoms. 
  On 
  the 
  emission 
  hypothesis, 
  

   therefore, 
  it 
  is 
  necessary 
  to 
  suppose 
  atoms 
  of 
  smaller 
  size. 
  The 
  

   method 
  of 
  experimenting 
  consisted 
  largely 
  in 
  the 
  use 
  of 
  Lecher's 
  

   arrangement 
  of 
  circuits 
  for 
  determining 
  wave 
  lengths 
  of 
  electrical 
  

   oscillations. 
  A 
  table 
  of 
  the 
  values 
  of 
  the 
  velocity 
  v 
  of 
  the 
  nega- 
  

   tive 
  atoms 
  is 
  given 
  in 
  comparison 
  with 
  the 
  velocity 
  V 
  of 
  light. 
  

   From 
  this 
  table 
  it 
  appears 
  that 
  the 
  velocity 
  v 
  is 
  about 
  -J- 
  of 
  that 
  of 
  

   light. 
  The 
  ratio 
  of 
  the 
  electrical 
  charge 
  to 
  the 
  mass 
  of 
  the 
  atom 
  

   is 
  of 
  the 
  order 
  4-64.10 
  17 
  or 
  3-04.10 
  17 
  .— 
  Wied. 
  Ann., 
  No. 
  12, 
  1899, 
  

   pp. 
  739-766. 
  j. 
  t. 
  

  

  12. 
  On 
  the 
  limits 
  of 
  hearing. 
  — 
  R. 
  Koenig 
  continues 
  his 
  investi- 
  

   gations* 
  of 
  the 
  upper 
  limit 
  of 
  hearing 
  and 
  discusses 
  the 
  applicabil- 
  

   ity 
  of 
  different 
  methods 
  of 
  study. 
  These 
  methods 
  consist 
  in 
  the 
  

   use 
  of 
  rods 
  vibrating 
  transversely, 
  rods 
  vibrating 
  longitudinally, 
  

   vibrating 
  plates 
  and 
  organ 
  pipes, 
  strings 
  and 
  membranes. 
  By 
  

   the 
  use 
  of 
  Kundt's 
  dust 
  figures, 
  the 
  notes 
  of 
  tuning 
  forks 
  from 
  

   c* 
  to 
  above 
  f 
  v 
  , 
  or 
  to 
  90,000 
  vibrations, 
  can 
  be 
  determined 
  with 
  

   great 
  accuracy. 
  Strings 
  and 
  membranes 
  are 
  unsuitable 
  for 
  the 
  

   determination 
  of 
  high 
  notes. 
  The 
  paper 
  concludes 
  with 
  a 
  full 
  

   summation 
  of 
  the 
  results 
  obtained. 
  — 
  Wied. 
  A?in.,J$o. 
  12, 
  1899, 
  

   pp. 
  721-738. 
  j. 
  t. 
  

  

  13. 
  Method 
  of 
  showing 
  periodic 
  current 
  curves. 
  — 
  Two 
  papers 
  

   have 
  appeared 
  on 
  this 
  subject 
  in 
  which 
  the 
  deviation 
  of 
  the 
  

   cathode 
  rays 
  by 
  an 
  electromagnet 
  is 
  employed 
  as 
  the 
  method 
  of 
  

   measurement. 
  A 
  bundle 
  of 
  cathode 
  rays 
  forms 
  a 
  luminous 
  spot 
  

   on 
  a 
  fluorescent 
  screen 
  and 
  the 
  position 
  of 
  this 
  spot 
  moves 
  as 
  the 
  

   bundle 
  is 
  deviated 
  periodically 
  by 
  the 
  influence 
  of 
  an 
  electro- 
  

   magnet. 
  In 
  fact 
  this 
  bundle 
  constitutes 
  an 
  index 
  of 
  no 
  weight 
  

   and 
  is 
  well 
  calculated 
  to 
  exhibit 
  the 
  periodical 
  changes 
  of 
  the 
  cur- 
  

   rent 
  which 
  excites 
  the 
  electromagnet. 
  The 
  method 
  is 
  due 
  to 
  

   F. 
  Braun 
  (Wied. 
  Ann., 
  lx, 
  p. 
  553, 
  1897). 
  It 
  is 
  elaborated 
  by 
  

   J. 
  Zenneck. 
  The 
  same 
  number 
  of 
  Wiedemann's 
  Annalen 
  also 
  

   contains 
  a 
  paper 
  on 
  the 
  same 
  method 
  by 
  A. 
  Wehnelt 
  and 
  B. 
  

   Donath, 
  who 
  described 
  a 
  simple 
  arrangement 
  of 
  the 
  Braun 
  

   cathode 
  tube 
  in" 
  combination 
  with 
  a 
  photographic 
  camera. 
  The 
  

   method 
  is 
  applied 
  by 
  the 
  last-named 
  writers 
  to 
  an 
  investigation 
  

   of 
  the 
  Wehnelt 
  electrolytic 
  interrupter, 
  and 
  they 
  conclude 
  that 
  

   the 
  Braun 
  tube 
  is 
  suitable 
  for 
  quantitative 
  measures 
  of 
  current 
  

   and 
  electromotive 
  force 
  curves. 
  — 
  Wied. 
  Ann., 
  No. 
  12, 
  1899, 
  

   8 
  61-870. 
  ' 
  J. 
  t. 
  

  

  * 
  See 
  this 
  volume, 
  p. 
  66. 
  

  

  