﻿220 
  Notices 
  respecting 
  New 
  Books. 
  

  

  Substituting 
  the 
  values 
  o£ 
  c 
  and 
  dc 
  in 
  terms 
  of 
  c' 
  and 
  dc 
  r 
  

   obtained 
  from 
  (7) 
  we 
  get 
  

  

  ^'= 
  RT 
  ( 
  2 
  -i^feH 
  

  

  Integrating 
  this 
  equation 
  we 
  get 
  p' 
  as 
  a 
  function 
  of 
  c', 
  

   i. 
  e., 
  of 
  yO 
  ; 
  substituting 
  this 
  in 
  (2) 
  we 
  get 
  P 
  and 
  from 
  (6) 
  

  

  — 
  in 
  the 
  form 
  

  

  In 
  order 
  to 
  draw 
  the 
  curve 
  of 
  fig. 
  1 
  the 
  integral 
  was 
  

   evaluated 
  graphically 
  using 
  the 
  constants 
  given 
  by 
  Kraus 
  

   and 
  Bray. 
  

  

  XXV. 
  Notices 
  respecting 
  New 
  Books. 
  

  

  Researches 
  of 
  the 
  Department 
  of 
  TerrdStrial 
  Magnetism. 
  Vol. 
  III. 
  

   Ocean 
  Magnetic 
  Observations 
  1905-1916, 
  and 
  Reports 
  on 
  Special 
  

   Researches. 
  By 
  L. 
  A. 
  Bauer, 
  Director, 
  Washington 
  D.C. 
  

   Published 
  by 
  the 
  Carnegie 
  Institution 
  of 
  Washington, 
  1917. 
  

   Quarto, 
  pp. 
  v 
  + 
  447, 
  with 
  25 
  plates 
  and 
  35 
  figures 
  in 
  the 
  

   text. 
  

  

  r 
  pHIS 
  volume 
  is 
  issued 
  also 
  in 
  three 
  parts, 
  dealing 
  respectively 
  

   -*- 
  with 
  the 
  earlier 
  magnetic 
  observations 
  taken 
  at 
  sea 
  by 
  the 
  

   ' 
  Galilee 
  ' 
  1905-1908, 
  the 
  later 
  sea 
  magnetic 
  observations 
  by 
  

   the 
  ' 
  Carnegie 
  ' 
  1909-1916, 
  and 
  the 
  results 
  of 
  the 
  observations 
  

   on 
  Atmospheric 
  Electricity 
  taken 
  on 
  both 
  vessels. 
  There 
  is 
  a 
  

   very 
  full 
  account 
  of 
  the 
  instruments, 
  the 
  methods 
  of 
  observation 
  

   and 
  the 
  reduction 
  formulae, 
  and 
  elaborate 
  tables 
  of 
  results 
  and 
  

   particulars 
  of 
  the 
  errors 
  in 
  existing 
  charts 
  — 
  American, 
  British, 
  

   and 
  Grerman. 
  The 
  vessels 
  and 
  the 
  instruments 
  are 
  illustrated 
  in 
  

   the 
  plates 
  from 
  a 
  variety 
  of 
  points 
  of 
  view. 
  Ihe 
  observing 
  vessel 
  

   ' 
  Carnegie 
  ' 
  was 
  specially 
  built 
  for 
  magnetic 
  work 
  and 
  is 
  almost 
  

   free 
  from 
  magnetic 
  material. 
  This 
  has 
  proved 
  a 
  great 
  simplification 
  

   in 
  the 
  reduction 
  of 
  the 
  observations. 
  

  

  