﻿Geological 
  Society. 
  679 
  

  

  of 
  the 
  original 
  material. 
  The 
  leak 
  due 
  to 
  the 
  final 
  product 
  

   was 
  2*5 
  scale 
  divs. 
  per 
  minute 
  or 
  nearly 
  40 
  times 
  the 
  normal 
  

   leak 
  of 
  the 
  electroscope. 
  Spectroscopic 
  examination 
  of 
  the 
  

   mineral 
  showed 
  that 
  titanium 
  was 
  present 
  in 
  large 
  quantity. 
  

   The 
  mineral 
  was 
  therefore 
  considered 
  to 
  be 
  anatase 
  or 
  rntile. 
  

  

  Some 
  of 
  the 
  mineral 
  was 
  tested 
  for 
  helium, 
  and 
  was 
  found 
  

   to 
  contain 
  about 
  1*5 
  c. 
  mm. 
  per 
  gram. 
  

  

  The 
  same 
  methods 
  were 
  applied 
  to 
  a 
  gneiss 
  from 
  the 
  

   Inner 
  Hebrides 
  and 
  the 
  radioactivity 
  was 
  found 
  to 
  be 
  con- 
  

   centrated 
  in 
  a 
  very 
  heavy, 
  non-magnetic 
  mineral, 
  occurring 
  

   in 
  very 
  small 
  crystals. 
  Examination 
  under 
  the 
  microscope 
  

   showed 
  this 
  to 
  be 
  zircon 
  ; 
  this 
  was 
  contirmed 
  by 
  spectro- 
  

   scopic 
  examination 
  which 
  showed 
  zirconium 
  to 
  be 
  present. 
  

   About 
  yij 
  gram 
  of 
  the 
  mineral 
  was 
  obtained 
  from 
  1 
  lb. 
  of 
  

   the 
  rock. 
  

  

  These 
  experiments 
  are 
  being 
  continued 
  on 
  other 
  rocks. 
  

  

  I 
  desire 
  to 
  thank 
  Prof. 
  Strutt 
  for 
  suo-oestiuo- 
  these 
  ex- 
  

   periments 
  and 
  for 
  his 
  interest 
  and 
  advice 
  throughout. 
  

  

  LXIX. 
  Proceedings 
  of 
  Learned 
  Societies, 
  

   GEOLOGICAL 
  SOCIETY. 
  

  

  [Continued 
  from 
  p. 
  440.] 
  

  

  March 
  10th, 
  1909.— 
  Prof. 
  W. 
  J. 
  Sollas, 
  LL.D., 
  Sc.D., 
  F.E.S., 
  

   President, 
  in 
  the 
  Chair. 
  

  

  HE 
  following 
  communications 
  were 
  read: 
  — 
  

  

  1. 
  ' 
  Some 
  Xotes 
  on 
  the 
  Xeighbourhood 
  of 
  the 
  Victoria 
  FaUs 
  

   (Khodesia).' 
  By 
  Thomas 
  Codrington, 
  M.Inst.C.E., 
  P.G.S. 
  

  

  The 
  author 
  gives 
  an 
  account 
  of 
  the 
  way 
  in 
  which 
  the 
  basalt 
  lies 
  

   in 
  the 
  valley 
  of 
  the 
  Zambesi 
  below 
  and 
  above 
  the 
  Victoria 
  Falls, 
  

   and 
  points 
  out 
  how 
  that 
  has 
  determined 
  the 
  features 
  of 
  the 
  river. 
  

   The 
  basalt 
  through 
  wliich 
  the 
  Batoka 
  Gorge 
  has 
  been 
  cut 
  ajDpears 
  

   in 
  the 
  course 
  of 
  the 
  Zambesi 
  for 
  2 
  miles 
  above 
  the 
  Victoria 
  Falls, 
  

   causing 
  rapids 
  over 
  rocky 
  bars 
  between 
  many 
  islands. 
  It 
  then 
  

   disappears, 
  and 
  the 
  river 
  above 
  flows 
  quietly 
  between 
  alluvial 
  flats 
  

   for 
  5 
  miles, 
  the 
  basalt 
  being 
  traceable 
  here 
  and 
  there 
  below 
  the 
  

   water 
  until 
  above 
  Caudahar 
  Island 
  it 
  again 
  rises 
  and 
  constitutes 
  

   the 
  bed 
  of 
  the 
  river 
  from 
  bank 
  to 
  bank, 
  causing 
  rapids 
  that 
  extend 
  

   for 
  many 
  miles 
  up 
  the 
  river. 
  Attention 
  is 
  called 
  to 
  a 
  wide 
  

   tributary 
  valley 
  which 
  joins 
  the 
  main 
  Zambesi 
  Valley 
  on 
  the 
  east 
  

   at 
  the 
  Falls 
  ; 
  and 
  to 
  the 
  Maramba 
  Kiver 
  flowing 
  down 
  it, 
  and 
  its 
  

   fluviatile 
  deposits. 
  The 
  discovery 
  of 
  stone-implements 
  and 
  arti- 
  

   ficiaUy-worked 
  stones 
  in 
  the 
  gravel 
  and 
  the 
  bed 
  of 
  the 
  Maramba 
  is 
  

   noted. 
  

  

  T 
  

  

  