﻿Dr. 
  P. 
  Chappuis 
  on 
  Gas- 
  Thermometry. 
  24H 
  

  

  form 
  as 
  the 
  curves 
  of 
  u 
  charge 
  " 
  and 
  " 
  discharge 
  " 
  of 
  a 
  

   condenser 
  appear 
  fairly 
  obvious. 
  

  

  Lord 
  Kelvin 
  showed 
  long 
  ago 
  in 
  his 
  paper 
  " 
  On 
  the 
  

   Theory 
  of 
  the 
  Electric 
  Telegraph 
  "*, 
  that 
  the 
  potential 
  and 
  

   the 
  current 
  at 
  any 
  point 
  in 
  the 
  wire 
  of 
  a 
  cable 
  can 
  be 
  ex- 
  

   pressed 
  by 
  appropriate 
  solutions 
  of 
  (1) 
  above. 
  In 
  precisely 
  

   the 
  same 
  manner, 
  by 
  use 
  of 
  solutions 
  of 
  (1) 
  we 
  can 
  treat 
  

   the 
  question 
  of 
  the 
  diffusion 
  of 
  electricity 
  into 
  or 
  out 
  of 
  the 
  

   dielectric 
  of 
  a 
  condenser. 
  That 
  such 
  a 
  dielectric 
  has 
  usually 
  

   an 
  enormous 
  resistance 
  per 
  centim. 
  compared 
  with 
  a 
  centim. 
  

   length 
  of 
  the 
  wire 
  of 
  a 
  cable, 
  does 
  not 
  alter 
  the 
  fact 
  that 
  the 
  

   law, 
  according 
  to 
  which 
  electric 
  diffusion 
  goes 
  on 
  in 
  both, 
  is 
  

   the 
  same. 
  Resistance 
  merely 
  affects 
  the 
  magnitude 
  of 
  the 
  

   proportion 
  of 
  distance, 
  or 
  of 
  time, 
  at 
  which 
  corresponding 
  

   states 
  of 
  potential 
  are 
  reached 
  in 
  the 
  dielectric 
  of 
  the 
  con- 
  

   denser 
  and 
  in 
  the 
  wire 
  of 
  the 
  cable. 
  In 
  the 
  case 
  of 
  a 
  distance 
  

   the 
  magnitude 
  of 
  this 
  proportion 
  may 
  be 
  of 
  the 
  order 
  10 
  -1 
  °, 
  

   in 
  the 
  case 
  of 
  a 
  time 
  it 
  may 
  be 
  of 
  the 
  order 
  10 
  20 
  . 
  

  

  The 
  whole 
  argument, 
  then, 
  may 
  be 
  summarized 
  in 
  the 
  

   statement 
  that 
  the 
  motion 
  of 
  the 
  model, 
  and 
  the 
  diffusion 
  of 
  

   electricity 
  in 
  the 
  dielectric 
  of 
  a 
  condenser, 
  are 
  subject 
  to 
  one 
  

   and 
  the 
  same 
  mathematical 
  law 
  expressed 
  by 
  equation 
  (1) 
  

   above. 
  

  

  In 
  conclusion, 
  I 
  would 
  take 
  the 
  liberty 
  of 
  suggesting 
  

   to 
  the 
  inventors 
  of 
  the 
  model 
  to 
  obtain 
  " 
  hysteresis 
  " 
  

   diagrams 
  by 
  cyclical 
  loading 
  of 
  the 
  springs. 
  I 
  feel 
  sure 
  that, 
  

   when 
  published, 
  such 
  diagrams 
  would 
  also 
  prove 
  extremely 
  

   instructive. 
  

  

  Gordon's 
  College, 
  Aberdeen, 
  

  

  3 
  uonege, 
  ADeraeen, 
  jn 
  

  

  Sept. 
  1901. 
  -A 
  [) 
  

  

  XXY. 
  Notes 
  on 
  Gas- 
  Thermometry 
  . 
  — 
  II. 
  By 
  Dr. 
  P. 
  Chappuis, 
  

   Attache 
  an 
  Bureau 
  International 
  des 
  Poids 
  et 
  Mesures, 
  

   Sevres 
  -j\ 
  

  

  MESSRS. 
  Holborn 
  and 
  Day 
  have 
  published 
  recently 
  in 
  

   a 
  research 
  on 
  the 
  air-thermometer 
  f 
  the 
  results 
  of 
  a 
  

   new 
  determination 
  of 
  the 
  expansion 
  of 
  Berlin 
  porcelain 
  

   between 
  0° 
  and 
  1000°. 
  

  

  These 
  experiments 
  are 
  of 
  considerable 
  importance 
  as 
  

  

  * 
  Math, 
  and 
  Phys. 
  Papers, 
  vol. 
  ii. 
  art. 
  lxxiii. 
  

  

  t 
  Communicated 
  by 
  the 
  Physical 
  Society 
  : 
  read 
  November 
  22, 
  1901. 
  

  

  X 
  Annalen 
  der 
  Phys. 
  unci 
  Chem. 
  4th 
  series, 
  vol. 
  ii. 
  1900, 
  p. 
  505. 
  

  

  R 
  2 
  

  

  