﻿PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  24 
  1 
  

  

  author 
  described 
  the 
  results 
  of 
  experiments 
  made 
  in 
  December 
  1881 
  

   on 
  some 
  lava 
  flowing 
  across 
  the 
  Atrio 
  del 
  Cavallo. 
  Favourable 
  cir- 
  

   cumstances 
  enabled 
  him 
  to 
  gain 
  a 
  position 
  above 
  a 
  perfectly 
  molten 
  

   stream, 
  the 
  surface 
  of 
  which 
  was 
  protected 
  from 
  radiation 
  by 
  the 
  

   heated 
  walls 
  of 
  a 
  tunnel 
  which 
  the 
  lava 
  had 
  already 
  formed 
  by 
  

   cooling 
  of 
  the 
  crust. 
  On 
  to 
  this 
  were 
  dropped, 
  from 
  a 
  height 
  of 
  

   1 
  1 
  yard 
  : 
  — 
  (a) 
  light 
  scoria 
  ; 
  this 
  floated 
  on 
  the 
  surface 
  until 
  lost 
  to 
  

   view 
  (the 
  stream 
  could 
  be 
  watched 
  for 
  150 
  yards 
  or 
  so) 
  : 
  (b) 
  fairly 
  

   solid 
  lava, 
  with 
  some 
  vesicular 
  cavities 
  ; 
  this 
  slowly 
  sank, 
  until 
  

   after 
  some 
  distance 
  it 
  disappeared 
  ; 
  (c) 
  the 
  most 
  compact 
  lava 
  that 
  

   could 
  be 
  found, 
  in 
  which, 
  however, 
  were 
  a 
  few 
  small 
  cavities 
  ; 
  this 
  

   sank 
  rapidly, 
  the 
  molten 
  rock 
  welling 
  up 
  round 
  it. 
  The 
  author 
  

   considered 
  that 
  these 
  experiments 
  demonstrate 
  that 
  the 
  cooled 
  lava 
  

   is 
  more 
  dense 
  than 
  the 
  molten, 
  and 
  that 
  the 
  apparently 
  contra- 
  

   dictory 
  results 
  obtained 
  by 
  Prof. 
  Palmieri 
  were 
  due 
  to 
  the 
  fact 
  that 
  

   the 
  surface 
  of 
  the 
  stream, 
  by 
  loss 
  of 
  heat, 
  had 
  become 
  viscid, 
  so 
  

   that 
  the 
  solid 
  material 
  floated, 
  though 
  of 
  greater 
  density. 
  The 
  

   author 
  concluded 
  by 
  citing 
  other 
  confirmatory 
  evidence 
  of 
  his 
  view. 
  

  

  The 
  following 
  specimens 
  were 
  exhibited 
  : 
  — 
  

  

  Specimens 
  of 
  Corals 
  from 
  the 
  Inferior 
  Oolite, 
  exhibited 
  by 
  

   R. 
  F. 
  Tomes, 
  Esq., 
  in 
  illustration 
  of 
  his 
  paper. 
  

  

  Specimens 
  of 
  Crinoids, 
  exhibited 
  by 
  P. 
  H. 
  Carpenter, 
  Esq., 
  in 
  

   illustration 
  of 
  his 
  paper. 
  

  

  Antlers 
  of 
  Cervus 
  &c, 
  exhibited 
  by 
  John 
  Gunn, 
  Esq. 
  

  

  The 
  original 
  of 
  Hybodus 
  Beclii, 
  Charlesworth, 
  a 
  specimen 
  of 
  the 
  

   rare 
  fish 
  Macropoma 
  Mantelli, 
  and 
  various 
  other 
  fossils, 
  exhibited 
  

   by 
  E. 
  Charlesworth, 
  Esq. 
  

  

  May 
  24, 
  1882. 
  

  

  J. 
  W. 
  Hulke, 
  Esq., 
  F.R.S., 
  President, 
  in 
  the 
  Chair 
  

  

  The 
  List 
  of 
  Donations 
  to 
  the 
  Library 
  was 
  read. 
  

  

  Four 
  models 
  were 
  presented 
  by 
  Dr. 
  Reyer, 
  illustrating 
  his 
  me- 
  

   moirs 
  on 
  the 
  Karst, 
  Predazzo, 
  tfec. 
  

  

  The 
  following 
  communications 
  were 
  read 
  : 
  — 
  

  

  1. 
  "On 
  the 
  Geology 
  of 
  Costa 
  Rica." 
  By 
  George 
  Attwood, 
  Esq., 
  

   F.G.S., 
  F.C.S., 
  Assoc. 
  Memb. 
  Inst.C.E. 
  ; 
  with 
  an 
  Appendix 
  by 
  W. 
  

   H. 
  Hudleston, 
  Esq., 
  M.A., 
  F.G.S., 
  F.C.S. 
  

  

  