Geological  Society.  421 
thermometers ;  the  phenomena  connected  with  the  change  of 
physical  state  ;  calorimetiy,  hygrometry,  and  heats  of  combination  ; 
the  laws  of  dynamics ;  waves  and  wave-motion ;  hydrodynamics, 
the  dynamics  of  gases,  and  thermodynamics. 
In  a  brief  review  snch  as  the  present,  it  would  be  impossible  to 
do  justice  to  the  wealth  of  learning  contained  in  this  work.  Not 
only  are  full  directions  given  for  the  successful  carrying  out  of  lecture 
experiments  on  a  large  scale  and  the  construction  of  various  forms 
of  apparatus,  but  the  work  abounds  in  most  interesting  passages 
relating  to  the  history  of  physics  and  the  gradual  evolution  of 
different  types  of  instruments.  In  many  instances  defects  are 
pointed  out  in  existing  forms  of  apparatus  as  usually  constructed, 
and  suggestions  are  made  for  improvements  ;  the  work  is  thus  one 
which  may  very  profitably  be  studied  by  manufacturers  of  physical 
apparatus.  Special  mention  must  be  made  of  the  numerous 
excellent  illustrations  which  adorn  the  book.  Teachers  of  physics 
desiring  to  become  proficient  in  the  art  of  lecture  illustration,  or 
having  to  prepare  estimates  of  laboratory  equipment,  would  do 
well  to  turn  to  this  unique  publication  for  information  on  these 
points. 
XXXVII.  Proceedings  of  Learned  Societies. 
GEOLOGICAL  SOCIETY. 
[Continued  from  p.  192.] 
December  20th,  1905.— J.  E.  Marr,  Sc.D.,  F.R.S.,  President, 
in  the  Chair. 
rpiIE  following  communications  were  read  :  — 
1. '  The  Highest  Silurian  Rocks  of  the  Ludlow  District.'  By  Miss 
Gertrude  L.  Elles,  D.Sc,  and  Miss  I.  L.  Slater,  Newnham  College, 
Cambridge. 
After  an  introduction  dealing  with  previous  work  in  the  district, 
the  authoresses  adopt  the  following  classification  of  the  beds : — 
Feet 
III.  Temeside 
f  B.  Temeside  or  Firry-  \  iin  +0  inn  f  Zone  of  Lingula  cornea 
J  pterusSkoXes..         J  {      and  Eurypterus. 
Ghoup.     1  A.  Downton-Castle  or "j     on  ,     r~     f  Zone    of    Lingula 
II.  UrpER 
Ludlow 
Group. 
Yellow  Sandstone.  J     '  }      minima. 
("B.  Upper  Whitcliffe    l1frnf    imfZone    of    Ckonetes 
or  Chonetes-Fhgs.  J  10U  t0  ' ou  \     striatella. 
1  A.  Lower  Whitcliffe  or  |  11A  ,     ,on]  Zone  of  Bhynchonella 
[     B}iync]wnclla-¥\ngs. )  iLUW  *■■--[      nueula. 
[  B.  Mocktreeor_D<yy/<y~  1     ,n       1 -n  f  Zone  of   Dayia   navi- 
I.  Aymestry     I  Shales.  J    4U  t0  iM  {     cxda. 
Group.     1  A.  Aymestry  or  Con-  \    75 +0  050  ■[  ^*one    °^     Gonclddium 
515  to  850 
