﻿Notices 
  respecting 
  New 
  Books. 
  201 
  

  

  The 
  lines 
  of 
  the 
  tin 
  spectrum 
  are 
  very 
  feeble. 
  With 
  the 
  

   magnetic 
  field 
  off, 
  the 
  lines 
  indicated 
  in 
  the 
  table 
  all 
  clearly 
  

   appeared 
  on 
  the 
  negative 
  after 
  an 
  exposure 
  of 
  15 
  minutes. 
  

   Exposing, 
  however, 
  with 
  the 
  field 
  on, 
  only 
  the 
  first 
  two 
  lines 
  

   were 
  on 
  the 
  plate, 
  notwithstanding 
  that 
  the 
  time 
  of 
  exposure 
  

   was 
  prolonged 
  to 
  23 
  minutes, 
  the 
  other 
  circumstances 
  being 
  the 
  

   same 
  as 
  before. 
  Apparently 
  the 
  first 
  and 
  the 
  last 
  two 
  lines 
  

   undergo 
  a 
  magnetic 
  change 
  ; 
  the 
  last 
  lines 
  (being 
  the 
  feeblest) 
  

   did 
  not 
  impress 
  their 
  components 
  on 
  the 
  plate. 
  The 
  com- 
  

   ponents 
  of 
  4585 
  were 
  so 
  feeble 
  that 
  they 
  disappeared 
  if 
  looked 
  

   at 
  through 
  the 
  microscope. 
  For 
  this 
  reason 
  I 
  have 
  made 
  a 
  

   scratch 
  at 
  each 
  of 
  the 
  components 
  by 
  means 
  of 
  a 
  needle, 
  and 
  

   have 
  measured 
  the 
  distance 
  of 
  these 
  scratches. 
  

   Amsterdam, 
  December 
  31, 
  1897. 
  

  

  XXII. 
  Notices 
  respecting 
  New 
  Books. 
  

  

  The 
  'Opus 
  Magus' 
  of 
  Roger 
  Bacon, 
  edited, 
  with 
  Introduction 
  and 
  

   Analytical 
  Table, 
  by 
  Johx 
  Henry 
  Bridges 
  (vol. 
  i. 
  pp. 
  188 
  + 
  404, 
  

   vol. 
  ii. 
  pp. 
  568). 
  Oxford 
  : 
  Clarendon 
  Press. 
  

  

  u 
  T>OGKEB 
  BACON, 
  Tun 
  des 
  plus 
  puissants 
  genies 
  du 
  Moyen 
  

   -■-V 
  age, 
  occupe 
  le 
  premier 
  rang 
  parmi 
  les 
  promoteurs 
  de 
  la 
  

   renaissance 
  generale 
  des 
  lettres 
  et 
  des 
  sciences. 
  II 
  contribua 
  

   particulierenient 
  aux 
  progres 
  des 
  Mathematiques 
  en 
  montrant, 
  

   dans 
  plusieurs 
  de 
  ses 
  ouvrages 
  {Op. 
  Maj.\ 
  quatrieme, 
  cinquieme 
  et 
  

   sixieme 
  parties), 
  le 
  rang 
  qu'elles 
  tiennent 
  dans 
  l'ensemble 
  des 
  con- 
  

   naissances 
  humaines, 
  et 
  les 
  secours 
  qu'elles 
  peuvent 
  procurer 
  dans 
  

   toutes 
  les 
  recherches 
  scientifiques, 
  dont 
  elles 
  sont 
  le 
  fondement. 
  

   Son 
  Optique 
  contient, 
  comme 
  tout 
  le 
  monde 
  le 
  sait, 
  de 
  savants 
  

   apergus 
  et 
  des 
  de'couvertes 
  reelles 
  en 
  theorie, 
  et 
  l'mvention 
  de 
  plu- 
  

   sieurs 
  instruments 
  devenus 
  de 
  la 
  plus 
  haute 
  utilite. 
  Ses 
  connais- 
  

   "sances 
  en 
  Astronomie 
  lui 
  firent 
  reconnaitre 
  les 
  erreurs 
  du 
  calen- 
  

   drier, 
  dont 
  il 
  concut 
  la 
  reformation. 
  Le 
  calendrier 
  qu'il 
  calcula, 
  et 
  

   qui 
  est 
  reste 
  manuscrit, 
  se 
  distingue 
  par 
  sa 
  correction 
  et 
  par 
  

   l'usage 
  des 
  chiffres 
  arabes, 
  qui 
  sont 
  les 
  memes 
  que 
  ceux 
  de 
  Sacro 
  

   Bosco." 
  So 
  writes 
  Chasles 
  in 
  his 
  Apercu 
  (p. 
  517), 
  and 
  the 
  same 
  

   verdict 
  is 
  pronounced 
  by 
  Hallam 
  and 
  other 
  writers 
  whom 
  we 
  have 
  

   consulted. 
  

  

  " 
  The 
  13th 
  century, 
  an 
  age 
  peculiarly 
  rich 
  in 
  great 
  men, 
  pro- 
  

   duced 
  few, 
  if 
  any, 
  who 
  can 
  take 
  higher 
  rank 
  than 
  Boger 
  Bacon. 
  

   He 
  is 
  in 
  every 
  way 
  worthy 
  to 
  be 
  placed 
  beside 
  such 
  thinkers 
  as 
  

   Albertus 
  Magnus, 
  Bonaventura, 
  and 
  Thomas 
  Aquinas 
  '*'* 
  (Encyc. 
  

   Britannica). 
  The 
  same 
  writer 
  quotes 
  Diihring 
  to 
  the 
  effect 
  that 
  

   Bacon 
  was 
  not 
  appreciated 
  by 
  his 
  age 
  because 
  he 
  was 
  so 
  completely 
  

   in 
  advance 
  of 
  it; 
  he 
  is 
  a 
  16th 
  or 
  17th 
  century 
  philosopher, 
  w 
  7 
  hose 
  

   lot 
  has 
  been 
  by 
  some 
  accident 
  cast 
  in 
  the 
  13th 
  century 
  ; 
  he 
  is 
  no 
  

   schoolman, 
  but 
  a 
  modern 
  thinker, 
  whose 
  conceptions 
  of 
  science 
  

   are 
  more 
  just 
  and 
  clear 
  than 
  are 
  even 
  those 
  of 
  his 
  more 
  celebrated 
  

  

  