﻿140 
  Scientific 
  Intelligence. 
  

  

  volume 
  is 
  undoubtedly 
  a 
  valuable 
  contribution 
  to 
  all 
  of 
  the 
  fields 
  

   to 
  which 
  it 
  relates. 
  h. 
  s. 
  u. 
  

  

  10. 
  Elements 
  of 
  the 
  Electromagnetic 
  Theory 
  of 
  Light; 
  by 
  

   Ludwik 
  Silberstein. 
  Pp. 
  vii, 
  48. 
  London, 
  1918 
  (Longmans, 
  

   Green 
  and 
  Co.). 
  — 
  "This 
  little 
  volume, 
  whose 
  object 
  is 
  to 
  present 
  

   the 
  essentials 
  of 
  the 
  electromagnetic 
  theory 
  of 
  light, 
  was 
  rewrit- 
  

   ten 
  . 
  . 
  . 
  from 
  my 
  Polish 
  treatise 
  on 
  Electricity 
  and 
  Magnetism 
  

   . 
  . 
  . 
  ." 
  This 
  text 
  affords 
  a 
  striking 
  example 
  of 
  the 
  elegance 
  

   and 
  compactness 
  of 
  presentation 
  which 
  may 
  be 
  attained 
  by 
  the 
  

   use 
  of 
  vectorial 
  notation 
  for, 
  in 
  less 
  than 
  fifty 
  pages, 
  the 
  author 
  

   has 
  condensed 
  all 
  the 
  salient 
  points 
  which 
  fall 
  under 
  the 
  follow- 
  

   ing 
  headings 
  : 
  1, 
  The 
  Origin 
  of 
  the 
  Electromagnetic 
  Theory 
  ; 
  2, 
  

   Advantages 
  of 
  the 
  Electromagnetic 
  over 
  the 
  Elastic 
  Theory 
  of 
  

   Light; 
  3, 
  Maxwell's 
  Equations. 
  Plane 
  Waves; 
  4, 
  Reflection 
  

   and 
  Refraction 
  at 
  the 
  Boundary 
  of 
  Isotropic 
  Media, 
  E 
  in 
  Plane 
  

   of 
  Incidence 
  ; 
  5, 
  Reflection 
  and 
  Refraction 
  ; 
  E 
  ± 
  Plane 
  of 
  Inci- 
  

   dence. 
  Note 
  on 
  the 
  Transition 
  Layer; 
  6, 
  Total 
  Reflection; 
  7, 
  

   Optics 
  of 
  Crystalline 
  Media: 
  General 
  Formulae 
  and 
  Theorems; 
  

   8, 
  The 
  Properties 
  of 
  the 
  Electrical 
  Axes 
  of 
  a 
  Crystal 
  ; 
  9, 
  Optical 
  

   Axes; 
  and 
  10, 
  "Uniaxial 
  Crystals. 
  Not 
  only 
  does 
  this 
  volume 
  

   merit 
  the 
  attention 
  of 
  the 
  general 
  scientific 
  reader 
  but 
  it 
  may 
  

   be 
  safely 
  and 
  especially 
  recommended 
  to 
  graduate 
  students 
  for 
  

   purposes 
  either 
  of 
  review 
  or 
  of 
  introduction. 
  h. 
  s. 
  u. 
  

  

  II. 
  Geology 
  and 
  Mineralogy. 
  

  

  1. 
  Thirty-Ninth 
  Annual 
  Report 
  of 
  the 
  Director 
  of 
  the 
  United 
  

   States 
  Geological 
  Survey, 
  George 
  Otis 
  Smith, 
  for 
  the 
  year 
  

   ending 
  June 
  30, 
  1918. 
  Pp. 
  163, 
  pis. 
  4.— 
  The 
  efficiency 
  of 
  the 
  

   Survey 
  organization, 
  the 
  reliability 
  of 
  its 
  work, 
  its 
  knowledge 
  

   of 
  the 
  resources 
  of 
  the 
  country, 
  and 
  the 
  ability 
  of 
  its 
  staff 
  have 
  

   been 
  put 
  to 
  the 
  test 
  during 
  the 
  past 
  year 
  with 
  results 
  that 
  are 
  

   highly 
  satisfactory. 
  From 
  a 
  peace 
  organization 
  engaged 
  in 
  

   scientific 
  research 
  it 
  was 
  converted, 
  as 
  it 
  were, 
  overnight 
  into 
  a 
  

   group 
  of 
  officers 
  engaged 
  in 
  military 
  surveys 
  and 
  in 
  searching 
  

   for 
  and 
  developing 
  methods 
  of 
  utilizing 
  war 
  minerals. 
  By 
  June 
  

   30, 
  322 
  members 
  of 
  the 
  Survey 
  were 
  enrolled 
  in 
  the 
  Army, 
  and 
  

   the 
  entire 
  topographic 
  branch 
  was 
  at 
  work 
  on 
  military 
  maps 
  at 
  

   home 
  and 
  in 
  France. 
  Another 
  large 
  group 
  was 
  engaged 
  in 
  

   searching 
  for 
  oil 
  and 
  developing 
  water 
  supplies; 
  and 
  problems 
  

   associated 
  with 
  the 
  discovery, 
  estimation, 
  and 
  development 
  of 
  

   manganese, 
  potash, 
  graphite, 
  chromium, 
  pyrite, 
  and 
  other 
  "war 
  

   minerals" 
  ^ 
  were 
  in 
  the 
  hands 
  of 
  special 
  committees. 
  The 
  

   amount 
  of 
  work 
  was 
  enormous; 
  for 
  example, 
  iron 
  and 
  steel 
  

   alloy 
  ores 
  were 
  examined 
  in 
  1580 
  localities 
  in 
  23 
  States 
  and 
  the 
  

   West 
  Indies. 
  The 
  country 
  is 
  indeed 
  fortunate 
  in 
  having 
  at 
  

   hand 
  this 
  large 
  force 
  of 
  highly 
  trained 
  men. 
  

  

  Although 
  pressing 
  war 
  needs 
  restricted 
  the 
  normal 
  activities 
  

  

  