﻿Notices 
  respecting 
  New 
  Boohs. 
  547 
  

  

  conception 
  of 
  \/-l 
  as 
  a 
  rotator 
  to 
  the 
  expression 
  o£ 
  the 
  same 
  

   idea 
  by 
  exponentials 
  of 
  imaginary 
  quantities. 
  Then 
  follow 
  

   developments 
  regarding 
  circular 
  motion, 
  damped 
  spiral 
  motion, 
  

   and 
  simple 
  harmonic 
  motion, 
  with 
  applications 
  to 
  various 
  types 
  of 
  

   circuit, 
  and 
  in 
  later 
  chapters 
  the 
  phenomena 
  of 
  the 
  oscillatory 
  

   discharge 
  and 
  mutual 
  induction 
  of 
  interlinked 
  circuits. 
  There 
  is 
  

   a 
  little 
  bit 
  of 
  criticism 
  of 
  Maxwell's 
  use 
  of 
  the 
  terms 
  lines 
  of 
  

   induction 
  and 
  lines 
  of 
  force, 
  which 
  might 
  mislead 
  the 
  reader 
  

   otherwise 
  unaware 
  of 
  the 
  fact 
  that 
  it 
  was 
  pre-eminently 
  Maxwell 
  

   who 
  brought 
  quantitative 
  clearness 
  into 
  the 
  relations 
  between 
  

   induced 
  electromotive 
  force 
  and 
  lines 
  of 
  induction. 
  The 
  term 
  

   Flux 
  takes 
  the 
  place 
  of 
  Maxwell's 
  lines 
  of 
  induction 
  or 
  Faraday's 
  

   lines 
  of 
  force. 
  Now 
  Professor 
  Patterson 
  begins 
  paragraph 
  60 
  

   with 
  these 
  words 
  : 
  " 
  To 
  show 
  that 
  it 
  is 
  flux 
  (Faraday's 
  lines 
  of 
  

   force) 
  and 
  not 
  field 
  strength 
  (Maxwell's 
  lines 
  of 
  force), 
  which 
  

   determines 
  electromotive 
  force, 
  we 
  may 
  consider, 
  etc." 
  The 
  

   author 
  does 
  not 
  mean 
  it, 
  but 
  the 
  inexperienced 
  reader 
  might 
  easily 
  

   imagine 
  that 
  Maxwell 
  regarded 
  flax 
  as 
  corresponding 
  to 
  his 
  lines 
  

   of 
  force. 
  Paragraphs 
  59 
  and 
  60 
  should 
  be 
  rewritten 
  so 
  as 
  to 
  

   make 
  quite 
  impossible 
  a 
  misunderstanding 
  on 
  this 
  point. 
  Maxwell 
  

   himself 
  was 
  perfectly 
  clear 
  and 
  perfectly 
  accurate. 
  

  

  Optical 
  Geometry 
  of 
  Motion 
  : 
  a 
  new 
  View 
  of 
  the 
  Theory 
  of 
  

   Relativity. 
  By 
  Alfred 
  A. 
  Eobb, 
  M. 
  A., 
  Ph.D. 
  Heffer 
  and 
  Sons. 
  

   Cambridge, 
  1911. 
  

   The 
  fundamental 
  idea 
  of 
  the 
  writer 
  of 
  this 
  pamphlet 
  is 
  that 
  

   the 
  axioms 
  of 
  geometry 
  are 
  the 
  formal 
  expression 
  of 
  certain 
  optical 
  

   facts. 
  The 
  most 
  elementary 
  experiment 
  of 
  vision 
  tells 
  us 
  when 
  

   three 
  points 
  lie 
  in 
  one 
  straight 
  line. 
  On 
  the 
  assumption 
  that 
  

   light 
  travels 
  from 
  particle 
  to 
  particle 
  in 
  straight 
  lines 
  with 
  a 
  

   definite 
  speed, 
  Mr. 
  Eobb 
  finds 
  in 
  the 
  difference 
  of 
  time 
  taken 
  by 
  a 
  

   flash 
  of 
  light 
  to 
  pass 
  in 
  different 
  directions 
  round 
  a 
  triangle 
  

   a 
  criterion 
  for 
  absolute 
  rotation. 
  The 
  system 
  is 
  worked 
  out 
  in 
  an 
  

   original 
  and 
  suggestive 
  manner, 
  and 
  leads 
  to 
  an 
  interesting 
  

   comparison 
  between 
  Euclidean 
  and 
  Lobatschefskijian 
  geometries. 
  

  

  Electromagnetic 
  Radiation 
  and 
  the 
  Mechanical 
  Reactions 
  arising 
  

   from 
  it. 
  Being 
  an 
  Adams 
  Prize 
  Essay 
  in 
  the 
  University 
  of 
  

  

  Cambridge. 
  By 
  G. 
  A. 
  Schott, 
  B.A., 
  D.Sc. 
  Cambridge 
  

  

  University 
  Press, 
  1912. 
  

   By 
  the 
  addition 
  of 
  seven 
  appendices 
  Professor 
  Schott 
  has 
  nearly 
  

   doubled 
  the 
  length 
  of 
  the 
  original 
  Essay, 
  for 
  which 
  the 
  Adams 
  

   Prize 
  was 
  awarded 
  in 
  1909. 
  Apart 
  altogether 
  from 
  the 
  value 
  of 
  

   the 
  author's 
  own 
  contributions 
  to 
  the 
  theory 
  of 
  moving 
  electrons, 
  

   the 
  mere 
  presentation 
  of 
  this 
  rapidly 
  growing 
  subject 
  in 
  a 
  

   connected 
  form 
  is 
  of 
  the 
  utmost 
  importance, 
  not 
  only 
  to 
  the 
  

   student 
  engaged 
  on 
  a 
  first 
  study 
  of 
  modern 
  electric 
  theory, 
  but 
  

   also 
  to 
  the 
  investigator 
  who 
  will 
  be 
  able 
  to 
  refresh 
  his 
  memory 
  on 
  

   many 
  difficult 
  points 
  without 
  having 
  recourse 
  to 
  the 
  scattered 
  

   memoirs 
  of 
  the 
  day. 
  It 
  would 
  be 
  impossible 
  in 
  a 
  short 
  review 
  to 
  

  

  