﻿396 
  Prof. 
  J. 
  Joly 
  on 
  the 
  

  

  field, 
  the 
  fact 
  that 
  they 
  are 
  secondary 
  bands 
  being 
  shown 
  by 
  

   their 
  motion 
  relative 
  to 
  the 
  primary 
  spectrum 
  when 
  the 
  

   echelon 
  is 
  given 
  a 
  slight 
  rotation. 
  The 
  secondary 
  bands 
  

   show 
  clearly 
  on 
  the 
  green 
  line 
  when 
  the 
  pressure 
  in 
  the 
  lamp 
  

   is 
  about 
  one 
  atmosphere. 
  

  

  This 
  research 
  was 
  commenced 
  at 
  the 
  request 
  of 
  Professor 
  

   Schuster, 
  and 
  I 
  have 
  much 
  pleasure 
  in 
  acknowledging 
  the 
  

   help 
  I 
  have 
  received 
  from 
  the 
  interest 
  he 
  has 
  taken 
  in 
  its 
  

   progress. 
  

  

  I 
  wish 
  to 
  thank 
  Mr. 
  E. 
  Marsden 
  for 
  assistance 
  in 
  my 
  

   first 
  experiments 
  on 
  the 
  secondary 
  effects, 
  and 
  Mr. 
  W. 
  A. 
  

   Harwood, 
  B.Sc, 
  for 
  measuring 
  several 
  of 
  the 
  photographs. 
  

   My 
  thanks 
  are 
  also 
  due 
  both 
  to 
  Professor 
  Schuster 
  and 
  to 
  

   Professor 
  Rutherford, 
  for 
  placing 
  the 
  resources 
  of 
  the 
  Physical 
  

   Laboratories 
  at 
  my 
  disposal. 
  

  

  XLY. 
  On 
  the 
  Radium- 
  Content 
  of 
  Sea 
  Water. 
  

   BijJ. 
  Joly, 
  F.R.S^ 
  

  

  IN 
  his 
  interesting 
  contribution 
  to 
  the 
  subject 
  of 
  the 
  radium- 
  

   content 
  of 
  sea 
  water 
  t, 
  Dr. 
  Eve 
  quotes 
  the 
  results 
  given 
  

   in 
  a 
  former 
  paper 
  of 
  mine 
  J. 
  The 
  general 
  results 
  of 
  my 
  

   subsequent 
  experiments 
  have 
  appeared 
  elsewhere 
  § 
  , 
  but 
  not 
  

   under 
  conditions 
  permitting 
  their 
  statement 
  in 
  detail 
  or 
  any 
  

   discussion 
  of 
  their 
  claims. 
  Although 
  incomplete 
  they 
  may 
  

   serve 
  to 
  define 
  more 
  fully 
  the 
  nature 
  of 
  the 
  difference 
  between 
  

   Dr. 
  Eve^s 
  observations 
  and 
  mine. 
  But 
  first 
  I 
  would 
  wish 
  to 
  

   call 
  attention 
  to 
  certain 
  points 
  of 
  agreement. 
  

  

  The 
  fact 
  of 
  very 
  considerable 
  differences 
  in 
  the 
  radium- 
  

   content 
  of 
  sea 
  water 
  from 
  one 
  locality 
  to 
  another, 
  seems 
  to 
  

   find 
  increased 
  confirmation 
  as 
  experiments 
  multiply. 
  In 
  my 
  

   paper 
  referred 
  to 
  by 
  Eve 
  these 
  variations 
  range 
  from 
  8 
  to 
  

   39 
  "3 
  (I 
  adopt 
  Eve^s 
  notation, 
  and 
  express 
  the 
  values 
  in 
  

   billion 
  ths 
  of 
  a 
  gram 
  per 
  litre). 
  This 
  variation 
  is 
  found 
  among 
  

   only 
  11 
  samples. 
  It 
  is 
  true 
  that 
  they 
  are 
  from 
  very 
  various 
  

   localities 
  and 
  include 
  harbour 
  water, 
  coastal 
  and 
  oceanic 
  

   waters, 
  and 
  extend 
  to 
  the 
  Arabian 
  Sea. 
  Eve 
  finds 
  even 
  wider 
  

   differences. 
  Here 
  I 
  must 
  point 
  out 
  that 
  by 
  an 
  oversight 
  Eve 
  

  

  * 
  Communicated 
  by 
  the 
  Author. 
  

  

  t 
  Phil. 
  Mag. 
  July 
  1909. 
  

  

  t 
  Phil. 
  Mag. 
  May 
  1908. 
  

  

  § 
  ' 
  Radioactivity 
  and 
  Geology,' 
  p. 
  46. 
  

  

  