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  XVII. 
  Notices 
  respecting 
  New 
  Books. 
  

   Lehebuch 
  deb. 
  Photochromie 
  {Photographie 
  der 
  natiirlichen 
  

   Farben). 
  Von 
  Wilhelm 
  Zenker. 
  -Neu 
  herausgegeben 
  von 
  

   Prof. 
  I)r. 
  B. 
  Schwalbe. 
  Mit 
  einein 
  Bildniss 
  des 
  Verfassers. 
  

   Braunschweig: 
  F. 
  Vieweg 
  und 
  Sohn, 
  1900. 
  Pp. 
  xiv+157. 
  

  

  IN 
  1810, 
  Seebeck 
  made 
  the 
  discovery 
  that 
  a 
  thin 
  layer 
  of 
  silver 
  

   chloride 
  when 
  exposed 
  to 
  the 
  light 
  of 
  the 
  spectrum 
  acquired 
  

   colours 
  which 
  to 
  some 
  extent 
  resembled 
  those 
  of 
  the 
  spectrum 
  

   itself. 
  This 
  highly 
  important 
  and 
  interesting 
  discovery, 
  published 
  

   in 
  Goethe's 
  Farbenlehre, 
  seems 
  to 
  have 
  attracted 
  very 
  little 
  

   attention 
  at 
  the 
  time, 
  and 
  was 
  consigned 
  to 
  oblivion, 
  until 
  John 
  

   Herschel 
  re-discovered 
  it 
  in 
  1841. 
  Herschel 
  carried 
  out 
  a 
  

   number 
  of 
  experiments 
  on 
  the 
  behaviour 
  of 
  silver 
  chloride 
  when 
  

   under 
  the 
  influence 
  of 
  the 
  light 
  of 
  a 
  spectrum, 
  and 
  his 
  work 
  was 
  

   continued 
  by 
  Edmond 
  Becquerel, 
  who 
  ultimately 
  succeeded 
  in 
  

   producing 
  photographs 
  in 
  colours. 
  Becquerel's 
  work 
  did 
  not 
  meet 
  

   with 
  the 
  recognition 
  which 
  it 
  merited, 
  and 
  many 
  of 
  his 
  results 
  

   appear 
  to 
  have 
  been 
  regarded 
  with 
  suspicion, 
  if 
  not 
  incredulity. 
  

   In 
  Germany, 
  however, 
  there 
  was 
  at 
  least 
  one 
  man 
  who 
  was 
  able 
  

   to 
  appreciate 
  to 
  the 
  full 
  the 
  practical 
  importance 
  of 
  Becquerel's 
  

   researches. 
  This 
  was 
  Wilhelm 
  Zenker, 
  who 
  in 
  1868 
  published 
  a 
  

   work 
  on 
  colour-photography 
  of 
  which 
  the 
  volume 
  under 
  review 
  is 
  

   a 
  reprint. 
  Zenker 
  repeated 
  most 
  of 
  Becquerel's 
  experiments, 
  and 
  

   a 
  photograph 
  in 
  colours 
  obtained 
  by 
  him 
  formed 
  a 
  frontispiece 
  to 
  

   his 
  work. 
  The 
  present 
  volume 
  contains 
  a 
  short 
  biographical 
  

   notice 
  of 
  Zenker 
  by 
  Dr. 
  Krech, 
  a 
  reprint 
  of 
  the 
  1868 
  edition 
  of 
  

   Zenker's 
  Photochromie, 
  and 
  an 
  appendix 
  on 
  recent 
  developments 
  

   by 
  E. 
  Tonn. 
  The 
  publishers 
  have 
  been 
  unable 
  to 
  reproduce 
  the 
  

   original 
  frontispiece, 
  as 
  in 
  the 
  copy 
  of 
  the 
  work 
  at 
  their 
  disposal 
  

   the 
  colours 
  were 
  so 
  faded 
  as 
  to 
  be 
  unrecognizable. 
  

  

  To 
  all 
  interested 
  in 
  the 
  subject 
  of 
  colour-photography, 
  the 
  book 
  

   may 
  be 
  recommended 
  as 
  a 
  simply 
  and 
  clearly 
  written 
  account 
  of 
  

   the 
  consecutive 
  steps 
  by 
  which 
  the 
  art 
  has 
  advanced 
  to 
  its 
  present 
  

   state 
  of 
  development. 
  

   La 
  Serie 
  de 
  Taylor 
  et 
  son 
  prolongement 
  analytique. 
  Par 
  Jacques 
  

  

  Hadamard. 
  Paris: 
  G. 
  Carre 
  et 
  C. 
  Naud, 
  1901. 
  (" 
  Scientia" 
  

  

  Series, 
  No. 
  12.) 
  Pp. 
  viii 
  f 
  102. 
  

   The 
  study 
  of 
  functions 
  of 
  a 
  complex 
  variable 
  has 
  given 
  rise 
  to 
  a 
  

   new 
  and 
  important, 
  branch 
  of 
  mathematics, 
  which 
  has 
  been 
  de- 
  

   veloping 
  with 
  phenomenal 
  rapidity, 
  and 
  has 
  already 
  furnished 
  the 
  

   key 
  to 
  many 
  interesting 
  problems 
  in 
  physics. 
  The 
  expansion 
  of 
  

   such 
  functions 
  by 
  Taylors 
  theorem, 
  and 
  the 
  discussion 
  of 
  the 
  

   regions 
  within 
  which 
  such 
  an 
  expansion 
  is 
  valid, 
  are 
  problems 
  of 
  

   considerable 
  complexity, 
  and 
  involve 
  the 
  consideration 
  of 
  many 
  

   nice 
  points. 
  The 
  little 
  book 
  before 
  us 
  is 
  a 
  concise 
  account 
  of 
  the 
  

   most 
  recent 
  work 
  on 
  this 
  subject, 
  and 
  should 
  prove 
  extremely 
  

   useful 
  to 
  mathematicians 
  interested 
  in 
  the 
  theory 
  of 
  functions. 
  

   The 
  value 
  of 
  the 
  book 
  is 
  enhanced 
  by 
  the 
  copious 
  bibliography 
  

   compiled 
  bv 
  the 
  author 
  for 
  the 
  use 
  of 
  readers 
  wishing 
  to 
  refer 
  to 
  

   original 
  sources 
  of 
  information. 
  

  

  