﻿232 
  Notices 
  respecting 
  New 
  Books. 
  

  

  Summary. 
  

  

  1. 
  X-rays 
  " 
  reflected" 
  from 
  crystals 
  have 
  the 
  general 
  

   properties 
  of 
  ordinary 
  X-rays. 
  

  

  2. 
  The 
  radiation 
  from 
  an 
  X-ray 
  tube 
  with 
  platinum 
  target 
  

   is 
  of 
  two 
  kinds, 
  (A) 
  radiation 
  of 
  indefinite 
  wave-length, 
  

   analogous 
  to 
  white 
  light, 
  (B) 
  five 
  types 
  of 
  monochromatic 
  

   radiation, 
  probably 
  characteristic 
  of 
  the 
  platinum. 
  

  

  3. 
  The 
  radiation 
  (A) 
  is 
  reflected 
  at 
  all 
  angles 
  of 
  incidence. 
  

   The 
  reflexion 
  has 
  been 
  studied 
  at 
  different 
  angles, 
  and 
  the 
  

   results 
  have 
  been 
  interpreted. 
  

  

  4. 
  Each 
  of 
  the 
  radiations 
  (B) 
  is 
  reflected 
  only 
  at 
  special 
  

   angles. 
  These 
  angles 
  have 
  been 
  measured 
  with 
  three 
  crystals, 
  

   and 
  the 
  results 
  are 
  in 
  good 
  agreement 
  with 
  the 
  simple 
  theory 
  

   deduced 
  from 
  the 
  principle 
  of 
  interference. 
  

  

  5. 
  The 
  wave-lengths 
  of 
  these 
  radiations 
  have 
  been 
  cal- 
  

   culated 
  to 
  be 
  1-642, 
  1-397, 
  1-375, 
  1-194, 
  1-157 
  x 
  K* 
  x 
  lO" 
  8 
  cm. 
  

   where 
  K 
  is 
  probably 
  either 
  1, 
  J, 
  or 
  J, 
  

  

  6. 
  Their 
  homogeneity 
  has 
  been 
  examined. 
  

  

  7. 
  An 
  attempt 
  has 
  been 
  made 
  to 
  estimate 
  the 
  distribution 
  

   of 
  energy 
  in 
  the 
  wave-lengths 
  for 
  the 
  general 
  X-rays. 
  

  

  We 
  wish 
  to 
  express 
  our 
  warmest 
  thanks 
  to 
  Prof. 
  Bragg 
  

   for 
  the 
  information 
  which 
  he 
  has 
  given 
  us 
  from 
  time 
  to 
  time 
  

   about 
  his 
  work 
  on 
  this 
  subject. 
  This 
  information 
  has 
  been 
  of 
  

   great 
  value 
  to 
  us. 
  

  

  We 
  also 
  wish 
  to 
  thank 
  Prof. 
  Rutherford 
  for 
  the 
  very 
  kind 
  

   interest 
  which 
  he 
  has 
  taken 
  in 
  our 
  work. 
  

  

  XY. 
  Notices 
  respecting 
  New 
  Books. 
  

  

  Results 
  of 
  Observations 
  made 
  at 
  the 
  Coast 
  and 
  Geodetic 
  Survey 
  

   Magnetic 
  Observatory 
  near 
  Tucson, 
  Arizona. 
  Washington. 
  

   Government 
  Printing 
  Office, 
  1913. 
  

  

  Tucson- 
  (32° 
  14'-8 
  N. 
  lat., 
  110° 
  50'-01 
  E. 
  long.) 
  is 
  a 
  new 
  magnetic 
  

   station 
  of 
  the 
  U.S. 
  Coast 
  and 
  Geodetic 
  Survey, 
  taking 
  the 
  place 
  

   of 
  Baldwin, 
  Kansas, 
  which 
  has 
  been 
  discontinued. 
  The 
  present 
  

   volume 
  describes 
  the 
  site, 
  and 
  the 
  construction 
  of 
  the 
  buildings, 
  

   which 
  were 
  built 
  in 
  1909, 
  and 
  gives 
  particulars 
  of 
  the 
  results 
  

   obtained 
  from 
  the 
  magnetographs 
  and 
  the 
  principal 
  earthquakes 
  

   recorded 
  by 
  a 
  Bosch-Omori 
  seismograph 
  down 
  to 
  the 
  end 
  of 
  

   1910. 
  The 
  volume 
  resembles 
  in 
  its 
  contents 
  and 
  the 
  order 
  of 
  their 
  

   presentation 
  the 
  biennial 
  volumes 
  issued 
  for 
  the 
  older 
  observatories 
  

   of 
  the 
  Survey. 
  

  

  