﻿Inversion 
  Temperature 
  of 
  Kelvin 
  Effect 
  in 
  Hydrogen. 
  535- 
  

  

  From 
  the 
  above 
  results 
  the 
  secular 
  variation 
  of 
  declination 
  

   is 
  as 
  follows 
  : 
  — 
  

  

  Period. 
  t 
  Secular 
  Variation. 
  

  

  1605 
  to 
  1839 
  7*56 
  increase 
  of 
  westerly 
  declination. 
  

  

  1841 
  „ 
  1850 
  130 
  

  

  1843 
  „ 
  1866 
  2-30 
  

  

  1866 
  „ 
  1869 
  Very 
  nearly 
  constant. 
  

  

  1870 
  ,, 
  1890 
  2-80 
  decrease 
  of 
  westerly 
  declination. 
  

  

  1890 
  „ 
  1900 
  3-91 
  

  

  § 
  4. 
  The 
  observations 
  for 
  intensity 
  are 
  fewer. 
  The 
  first 
  

   recorded 
  trustworthy 
  observation 
  was 
  made 
  in 
  1843. 
  So 
  far 
  

   as 
  is 
  known 
  to 
  us, 
  the 
  results 
  of 
  all 
  observations 
  made 
  since 
  

   that 
  date 
  are 
  contained 
  in 
  the 
  following 
  list. 
  The 
  results 
  are 
  

   given 
  in 
  c.G.S. 
  units. 
  

  

  Horizontal 
  Total 
  

  

  Date. 
  Observer. 
  Intensity. 
  Intensity. 
  Authorities. 
  

  

  1843. 
  E. 
  A. 
  Detachment... 
  -2089 
  -3498^ 
  

  

  ]lf- 
  » 
  » 
  - 
  |°|| 
  *W> 
  Sabine, 
  'Magnetical 
  and 
  Me- 
  

  

  }lta 
  q 
  " 
  11 
  " 
  "•* 
  onsn 
  L 
  teorological 
  Observation* 
  

  

  1846. 
  bmalley 
  -2080 
  Y 
  at 
  Cape 
  of 
  Good 
  Hope,' 
  

  

  t»47. 
  :, 
  -U/< 
  i 
  • 
  

  

  1848. 
  ., 
  -2072 
  V01 
  * 
  1 
  - 
  

  

  1850. 
  „ 
  -2066 
  ) 
  

  

  1852. 
  Maclear 
  -2059 
  "3506 
  1 
  

  

  1853. 
  „ 
  -2056 
  -3511 
  ! 
  

  

  I2& 
  " 
  fX2 
  SIS 
  ^Magnetic 
  Records, 
  E. 
  Obs. 
  

  

  1856: 
  :; 
  ::::::::::::::: 
  l>£ 
  Sill 
  c 
  aP 
  eofGo 
  aHo 
  P 
  e. 
  

  

  1857, 
  „ 
  -2041 
  -3507 
  J 
  

  

  Sept. 
  1857 
  -2056 
  -3684 
  Eeise 
  der 
  ' 
  Gazelle.' 
  

  

  1Q7Q.Q 
  oqcq 
  .oKKi 
  / 
  'Challenger' 
  Eeport, 
  Narra- 
  

  

  18739 
  1989 
  oj51 
  I 
  tive,Tol.ii. 
  

  

  1890-1. 
  Preston 
  -1916 
  -3542 
  { 
  U 
  &^b^»*^ 
  

  

  }®*f 
  « 
  "}!£2r 
  'US* 
  I 
  Magnetic 
  Eecords, 
  E. 
  Obs. 
  

  

  wit 
  %*&• 
  *'•£"" 
  '«?? 
  '? 
  Cape 
  of 
  Good 
  Hope. 
  

  

  1901-0. 
  Beattie 
  & 
  Morrison. 
  -1851 
  -3^59 
  ) 
  v 
  

  

  Secular 
  Variation. 
  

  

  Horizontal 
  Intensity. 
  Total 
  Intensity. 
  

  

  1843 
  to 
  1855 
  -00035 
  annual 
  decrease. 
  -00016 
  annual 
  increase. 
  

  

  1855 
  „ 
  1901 
  -00043 
  „ 
  „ 
  -00009 
  „ 
  

  

  1890-1 
  ,, 
  1901 
  -00059 
  „ 
  „ 
  ? 
  

  

  Capetown, 
  February 
  1902. 
  

  

  LXII. 
  Determination 
  of 
  Inversion 
  Temperature 
  of 
  Kelvin 
  

   Effect 
  in 
  Hydrogen. 
  By 
  K. 
  Olszewski 
  *. 
  

  

  IN 
  1854, 
  Kelvin 
  and 
  Joule 
  showed 
  that 
  during 
  an 
  irre- 
  

   versible 
  expansion 
  hydrogen 
  behaves 
  differently 
  from 
  all 
  

   other 
  gases 
  : 
  — 
  while 
  air 
  in 
  expanding 
  from 
  a 
  higher 
  to 
  a 
  

   lower 
  pressure 
  without 
  the 
  performance 
  of 
  external 
  work 
  is 
  

   * 
  Communicated 
  by 
  the 
  Author. 
  

  

  