﻿Geological 
  Society. 
  831 
  

  

  to 
  be 
  a 
  book 
  which 
  is 
  destined 
  to 
  take 
  a 
  leading 
  place 
  amongst 
  

   expositions 
  of 
  electromagnetic 
  theory. 
  Mr. 
  Jeans 
  is 
  so 
  thoroughly 
  

   alive 
  to 
  the 
  logical 
  principles 
  at 
  the 
  foundation 
  of 
  his 
  subject 
  that 
  

   he 
  is 
  able 
  to 
  lucidly 
  expound 
  them. 
  Take, 
  for 
  example, 
  the 
  

   question 
  of 
  action 
  at 
  a 
  distance 
  discussed 
  on 
  p. 
  133. 
  Then 
  again 
  

   the 
  numerical 
  illustrations 
  are 
  very 
  strikiug. 
  By 
  no 
  means 
  the 
  

   slightest 
  feature 
  of 
  the 
  book 
  is 
  the 
  large 
  number 
  of 
  examples 
  at 
  

   the 
  ends 
  of 
  the 
  chapters. 
  These, 
  as 
  he 
  says, 
  " 
  may 
  provide 
  problems 
  

   for 
  the 
  mathematical 
  student, 
  but 
  it 
  is 
  hoped 
  that 
  they 
  may 
  also 
  

   form 
  a 
  sort 
  of 
  compendium 
  of 
  results 
  for 
  the 
  physicist, 
  shovving 
  

   what 
  types 
  of 
  problem 
  admit 
  of 
  exact 
  mathematical 
  solution." 
  

  

  LXXII. 
  Proceedings 
  of 
  Learned 
  Societies. 
  

  

  GEOLOGICAL 
  SOCIETY. 
  

  

  [Continued 
  from 
  p. 
  704.] 
  

  

  May 
  20th, 
  1908.— 
  Prof. 
  W. 
  J. 
  Sollas, 
  Sc.D., 
  LL.D., 
  F.B.S., 
  

  

  President, 
  in 
  the 
  Chair. 
  

  

  r 
  piEE 
  following 
  communications 
  were 
  read 
  : 
  — 
  

  

  1. 
  ' 
  On 
  some 
  Fossil 
  Pishes 
  discovered 
  by 
  Prof. 
  Ennes 
  de 
  Souza 
  

   in 
  the 
  Cretaceous 
  Formation 
  at 
  Ilheos, 
  State 
  of 
  Bahia 
  (Brazil).' 
  

   By 
  Arthur 
  Smith 
  Woodward, 
  LL.D., 
  F.R.S., 
  F.L.S., 
  V.P.G.S. 
  

  

  2. 
  ' 
  The 
  Bala 
  and 
  Llandoverv 
  Bocks 
  of 
  Glyn 
  Ceiriog 
  (North 
  

   Wales).' 
  Bv 
  Dr. 
  Theodore 
  Groom, 
  M.A., 
  F.G.S., 
  and 
  Philip 
  Lake, 
  

   M.A., 
  F.G.S* 
  

  

  In 
  the 
  district 
  around 
  Glyn 
  Ceiriog, 
  which 
  the 
  authors 
  have 
  

   mapped 
  on 
  the 
  6-inch 
  scale, 
  the 
  following 
  succession 
  is 
  given 
  : 
  — 
  

   Denbighshire 
  Slates. 
  

  

  Ty-Draw 
  Slates, 
  with 
  Monograptus 
  Marri 
  ") 
  Tarannon 
  

  

  Fron-Frys 
  Slates, 
  with 
  Pentamerus 
  undatus, 
  Meristina 
  cf. 
  crassa, 
  L 
  and 
  

  

  Nidulites 
  favus, 
  etc 
  J 
  Llandovery. 
  

  

  <^.Valle 
  y 
  Series 
  { 
  £> 
  g^' 
  «££°>%™ 
  Jj&Z 
  

  

  Hisingeri, 
  Ramipora 
  Hochstetteri, 
  Trinucleus 
  

   seticornis, 
  species 
  of 
  Cybele, 
  Cheirurus, 
  Bemo- 
  

   pleurides, 
  and 
  numerous 
  cystids, 
  corals, 
  i 
  

  

  brachiopoda, 
  etc 
  

  

  Graptolite-Slates, 
  with 
  Dicellograptus 
  elegans 
  , 
  

  

  Gap. 
  

  

  ((e) 
  Pen-y-Graig 
  Ash 
  

  

  I 
  (d) 
  Bryn 
  Beds, 
  with 
  Tetradella 
  complicata, 
  Phacops 
  

   apiculatics, 
  Trinucleus 
  concentricus, 
  Triplesia 
  

  

  Pandy 
  J 
  spiriferoides, 
  Safinesguina 
  ungula, 
  etc 
  

  

  Series. 
  ] 
  (c) 
  Craig-y-Pandy 
  Ash 
  

  

  I 
  (b) 
  Teirw 
  Beds, 
  with 
  Lingula 
  tenuigranulata, 
  

   Bellerophon 
  nodosus, 
  Asaphus 
  Powisi, 
  etc. 
  ... 
  

   {(a) 
  Cwm-Clwyd 
  Ash 
  ; 
  

  

  Y 
  Bala. 
  

  

  In 
  the 
  Pandy 
  Series 
  the 
  beds 
  a, 
  c, 
  and 
  e 
  cousist 
  essentially 
  or 
  

  

  