﻿Earth's 
  Penetrating 
  Radiation 
  with 
  Waif 
  Electrometer. 
  741 
  

  

  generated 
  in 
  the 
  same 
  vessel 
  on 
  a 
  steamer 
  on 
  the 
  Atlantic 
  was 
  

   only 
  about 
  6*03 
  ions 
  per 
  c.c. 
  per 
  sec. 
  

  

  The 
  readings 
  on 
  the 
  Atlantic 
  were 
  taken 
  with 
  difficulty 
  on 
  

   account 
  of 
  the 
  continued 
  oscillation 
  impressed 
  upon 
  the 
  

   gold-leaf 
  system 
  by 
  the 
  swaying 
  of 
  the 
  steamer. 
  As 
  a 
  result 
  

   these 
  readings 
  were 
  not 
  considered 
  to 
  have 
  the 
  same 
  reliability 
  

   as 
  those 
  taken 
  on 
  land 
  at 
  the 
  different 
  points 
  of 
  observation. 
  

  

  With 
  a 
  view 
  to 
  obtaining 
  more 
  reliable 
  observations 
  on 
  

   the 
  surface 
  of 
  the 
  ocean 
  a 
  second 
  set 
  of 
  readings 
  was 
  taken 
  

   when 
  crossing 
  the 
  Atlantic 
  in 
  September 
  1912, 
  and 
  again 
  a 
  

   third 
  one 
  when 
  crossing 
  in 
  June 
  of 
  the 
  present 
  year. 
  This 
  

   time, 
  however, 
  a 
  Wulf 
  bifihir 
  electrometer 
  was 
  used. 
  The 
  

   instrument 
  behaved 
  admirably, 
  and 
  with 
  it 
  readings 
  were 
  

   taken 
  on 
  board 
  ship 
  with 
  the 
  same 
  ease 
  as 
  on 
  land. 
  

  

  II. 
  Apparatus 
  and 
  theory 
  of 
  Instrument. 
  

   The 
  form 
  of 
  the 
  instrument 
  used 
  is 
  shown 
  in 
  fig. 
  1. 
  It 
  

  

  Fio-. 
  1. 
  

  

  consists 
  of 
  a 
  cylindrical 
  receiver 
  of 
  zinc 
  provided 
  with 
  plane 
  

   sides 
  which 
  had 
  a 
  capacity 
  of 
  about 
  two 
  litres. 
  The 
  electrical 
  

   Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  26. 
  No. 
  154. 
  Oct. 
  1913. 
  3 
  D 
  

  

  