﻿744 
  Prof. 
  McLennan 
  and 
  Mr. 
  McLeod: 
  Measurements 
  on 
  

  

  A 
  set 
  of 
  readings 
  taken 
  with 
  instrument 
  ah 
  Cambrido-e, 
  

   England, 
  is 
  given 
  in 
  Table 
  L, 
  and 
  a 
  curve 
  representing 
  them 
  

  

  Table 
  I. 
  

  

  Time 
  in 
  minutes. 
  

  

  Potential 
  of 
  electrical 
  system. 
  

  

  

  

  221 
  volts. 
  

  

  86 
  

  

  209 
  

  

  164 
  

  

  197-9 
  

  

  257 
  

  

  1855 
  

  

  351 
  

  

  172-1 
  

  

  442 
  

  

  159-5 
  

  

  495 
  

  

  151-3 
  

  

  Volts 
  

   230 
  

  

  210 
  

   £00 
  

  

  (90 
  

  

  ;so 
  

  

  160 
  

  

  400 
  500 
  

  

  AttNUTES. 
  

  

  

  is 
  shown 
  in 
  fig. 
  2. 
  These 
  serve 
  to 
  exhibit 
  the 
  constancy 
  of 
  

   the 
  ionization 
  produced 
  by 
  the 
  penetrating 
  rays 
  at 
  the 
  point 
  

   of 
  observation 
  for 
  a 
  period 
  of 
  time 
  extending 
  over 
  eio-ht 
  

   hours. 
  

  

  