D.  VAN  NOSTRAND.  31

Rogers’  G-eology  of  Pennsylvania.
3  Yols.  4to,  with  Portfolio  of  Maps.  Cloth.  $30.00.
THE  GEOLOGY  OF  PENNSYLVANIA.  A  Government  Survey.
  With  a  general  view  of  the  Geology  of  the  United  States,
Essays  on  the  Coal  Formation  and  its  Fossils,  and  a  description
of  the  Coal  Fields  of  North  America  and  Great  Britain.  By
Henry  Darwin  Hogers,  Late  State  Geologist  of  Pennsylvania.
Splendidly  illustrated  with  Plates  and  Engravings  in  the  Text.
It  certainly  should  be  in  every  public  library  „nroughout  the  country,  and
likewise  in  the  possession  of  all  students  of  G-eology.  After  the  final  aale  of
these  copies,  the  work  will,  of  course,  become  more  valuable.
The  work  for  the  last  five  years  has  been  entirely  out  of  the  market,  but  a
few  copies  that  remained  in  the  hands  of  Prof.  Rogers,  in  Scotland,  at  the
time  of  his  death,  are  now  offered  to  the  public,  at  a  price  which  is  eren
below  what  it  was  originally  sold  for  when  first  published.

Morfit  on  Pure  Fertilizers.
With  28  Illustrative  Plates.  8vo.  Cloth.  $20.00.
A  PEACTICAL  TEEATISE  ON  PUEE  FERTILIZERS,  and
the  Chemical  Conversion  of  Eock  Guanos,  Marlstones,  Coprolites,
and  the  Grude  Phosphates  of  Lime  and  Alumina  Generally,  into
yarious  Valuable  Products.  By  Campbell  Morfit,  M.D.,  F.C.S.

Sweet’s  Report  on  Coal.
8vo.  Cloth.  $3.00.  ■
SPECIAL  EEPORT  ON  COAL  ;  showing  its  Distribution,  Classification, ­
  and  Cost  delivered  over  different  routes  to  yarious  points
in  the  State  of  New  York,  and  the  principal  cities  on  the  Atlantic
Coast.  By  S.  H.  Sweet.  With  maps.

Colburn’s  Gas  Works  of  London.
lämo.  Boards.  60  Cents.
.  GAS  WORKS  OF  LONDON.  By  Zekah  Colbukn.