﻿62 
  Prof. 
  Barton 
  and 
  Miss 
  Browning 
  on 
  

  

  maximum 
  width 
  of 
  spark-gap 
  used 
  was 
  45 
  mm., 
  the 
  spheres 
  

   being 
  31 
  mm. 
  in 
  diameter; 
  so 
  that 
  according 
  to 
  tests 
  made 
  

   by 
  C. 
  Muller* 
  the 
  voltage 
  applied 
  could 
  not 
  have 
  exceeded 
  

   50 
  KV. 
  The 
  K-series 
  could 
  not 
  then 
  have 
  been 
  excited, 
  and 
  

   it 
  is 
  probable 
  that 
  the 
  wave-length 
  excited 
  belonged 
  to 
  the 
  

   L-series 
  of 
  either 
  metal. 
  

  

  I 
  propose 
  to 
  investigate 
  further 
  the 
  wave-lengths 
  and 
  other 
  

   properties 
  of 
  these 
  radiations. 
  A 
  report 
  of 
  such 
  studies 
  will 
  

   be 
  published 
  shortly. 
  

  

  Summary 
  of 
  Results. 
  

  

  1. 
  For 
  the 
  first 
  time 
  the 
  excitation 
  of 
  a 
  penetrating 
  radiation 
  

  

  by 
  positive 
  rays 
  was 
  observed. 
  This 
  effect 
  was 
  retained 
  

   on 
  photographic 
  plates 
  in 
  the 
  case 
  of 
  tin 
  and 
  lead, 
  and 
  

   it 
  is 
  surmised 
  that 
  it 
  is 
  the 
  characteristic 
  X-radiation 
  

   of 
  these 
  elements. 
  

  

  2. 
  A 
  lower 
  limit 
  was 
  found 
  to 
  exist 
  for 
  the 
  voltage 
  necessary 
  

  

  for 
  excitation. 
  

  

  3. 
  Einstein's 
  quantum 
  condition 
  leads 
  to 
  the 
  supposition 
  

  

  that 
  the 
  new 
  effect 
  that 
  has 
  been 
  observed 
  is 
  excitation 
  

   of 
  the 
  L- 
  characteristic 
  rays 
  of 
  either 
  element. 
  

  

  The 
  Physical 
  Laboratory, 
  

   Technical 
  High 
  School 
  of 
  Zurich. 
  

   August 
  1917. 
  

  

  VIII. 
  Variably- 
  Coupled 
  Vibrations: 
  II. 
  Unequal 
  Masses 
  or 
  

   Periods. 
  By 
  Edwin 
  H. 
  Barton, 
  D.Sc, 
  F.R.S., 
  Professor 
  

   of 
  Physics, 
  and 
  H. 
  Mary 
  Browning, 
  B.Sc, 
  Lecturer 
  and 
  

   Demonstrator 
  in 
  Physics, 
  University 
  College, 
  Nottingham^. 
  

  

  [Plates 
  I. 
  & 
  n.] 
  

  

  Contents. 
  

  

  Page 
  

  

  I. 
  Introduction 
  63 
  

  

  II. 
  Theory 
  for 
  Unequal 
  Masses 
  63 
  

  

  Equations 
  of 
  Motion 
  and 
  Coupling. 
  

   Solution 
  and 
  Frequencies. 
  

   Initial 
  Conditions. 
  

   Dampings, 
  Separate 
  and 
  Coupled. 
  

  

  III. 
  Theory 
  eor 
  Unequal 
  Periods 
  69 
  

  

  Equations 
  of 
  Motion 
  and 
  Coupling. 
  

   Solution 
  and 
  Frequencies. 
  

   Initial 
  Conditions. 
  

  

  IV. 
  Relations 
  among 
  Variables 
  72 
  

  

  * 
  C. 
  Muller, 
  Ann. 
  d. 
  Phys. 
  [4] 
  xxviii. 
  p. 
  585 
  (1910). 
  

   f 
  Communicated 
  by 
  the 
  Authors, 
  

  

  