﻿Magnetic 
  Elements 
  at 
  the 
  Cape 
  of 
  Good 
  Hope. 
  

  

  Date. 
  

  

  Observers. 
  

  

  Dip. 
  

  

  Authority 
  

  

  533 
  

  

  Remarks. 
  

  

  1751. 
  LaCaille 
  -43 
  

  

  1770. 
  Ekeberg 
  -44 
  

  

  1774. 
  Bavlev 
  —45 
  

  

  1774. 
  Ekeberg 
  -44 
  

  

  1775. 
  Wales 
  r 
  -45 
  

  

  1775. 
  Abercrombie 
  —46 
  

  

  1776. 
  Baylev 
  -46 
  

  

  1780. 
  Bayley 
  -46 
  

  

  1791. 
  Vancouver 
  —48 
  

  

  1792. 
  Dentrecasteaux 
  —47 
  

  

  1818. 
  Freycinet 
  -50 
  

  

  1836. 
  Fitzroy 
  -52 
  

  

  1839. 
  Du 
  Petit 
  Thouars. 
  -53 
  

  

  1840. 
  Ross 
  -53 
  

  

  1841. 
  R.A. 
  Detachment. 
  . 
  -53 
  

  

  1842. 
  R.A. 
  „ 
  ... 
  -53 
  

  

  1843. 
  R.A. 
  „ 
  ... 
  -53 
  

  

  1844. 
  R.A. 
  „ 
  ... 
  -53 
  

  

  1845. 
  R.A. 
  „ 
  ... 
  -53 
  

  

  1846. 
  R.A. 
  „ 
  ... 
  -53 
  

  

  1847 
  -53 
  

  

  1848 
  -53 
  

  

  1849. 
  ,. 
  -53 
  

  

  1850 
  -53 
  

  

  6, 
  1851. 
  Sir 
  Thomas 
  Maclear. 
  —54 
  

  

  1852 
  -54 
  

  

  1853 
  -54 
  

  

  1854 
  -54 
  

  

  1855 
  -54 
  

  

  1856 
  -54 
  

  

  1857 
  -54 
  

  

  1857 
  -54 
  

  

  1858 
  -54 
  

  

  1871. 
  Stone 
  —55 
  

  

  1871. 
  Stone 
  -55 
  

  

  Not. 
  1873 
  -55 
  

  

  Sept. 
  30, 
  1874 
  -56 
  

  

  Jan. 
  31, 
  1890. 
  Preston 
  -57 
  

  

  1894. 
  Combe 
  -57 
  

  

  1895. 
  Finlay 
  -57 
  

  

  1897. 
  Finlay 
  -58 
  

  

  1899. 
  Beattie 
  & 
  Morrison. 
  -58 
  

  

  1900. 
  Beattie 
  & 
  Morrison. 
  - 
  58 
  

   1900. 
  Beattie 
  & 
  Morrison. 
  -58 
  

   1900. 
  Beattie 
  & 
  Morrison. 
  -58 
  

  

  From 
  Sabine's 
  ' 
  Magne- 
  

   tical 
  and 
  Meteorolo- 
  

   gical 
  Observations 
  at 
  

   the 
  Cape 
  of 
  Good 
  

   Hope,' 
  Vol. 
  I. 
  Mag- 
  

   netism. 
  

  

  Admiralty 
  hyclrogra- 
  

   phic 
  records. 
  

  

  Sabine. 
  

  

  Dip-book 
  Royal 
  Observ. 
  

   C. 
  of 
  Gr. 
  Hope. 
  

  

  The 
  results 
  for 
  1S41 
  to 
  

   1846 
  inclusive 
  are 
  the 
  

   mean 
  of 
  observations 
  

   taken 
  as 
  a 
  rule 
  twice 
  

   weekly, 
  four 
  hours 
  

   before 
  and 
  four 
  hours 
  

   after 
  noon, 
  

  

  The 
  results 
  for 
  1852- 
  

   1857 
  inclusive 
  are 
  the 
  

   mean 
  of 
  observations 
  

   taken 
  twice 
  weekly, 
  

   morning 
  and 
  after- 
  

   noon. 
  

  

  Reise 
  der 
  Novara. 
  

  

  Dip-book 
  R. 
  O., 
  C. 
  of 
  

   G. 
  Hope. 
  

  

  ' 
  Challenger 
  ' 
  Report, 
  

  

  Narrative 
  ii.. 
  

   Voyage 
  of 
  the 
  'Gazelle.' 
  

   U.S. 
  Coast 
  and 
  Geodetic 
  

  

  Survey, 
  Bull. 
  23. 
  

  

  R. 
  O. 
  Records, 
  C. 
  of 
  G. 
  

   Hope. 
  

  

  ). 
  With 
  Dip 
  Circle 
  9, 
  

  

  ^ 
  ^ 
  -r. 
  ■, 
  '^ 
  r 
  ^ 
  hv 
  Dover. 
  

  

  R. 
  O. 
  Records, 
  C. 
  of 
  G. 
  

  

  Hope. 
  J 
  

  

  With 
  Dip 
  Circle 
  

   142, 
  by 
  Dover. 
  

  

  From 
  the 
  above 
  results 
  the 
  secular 
  variation 
  of 
  inclination 
  

   is 
  as 
  follows 
  : 
  — 
  

  

  Period. 
  

  

  Secular 
  Variation. 
  

  

  1751 
  to 
  1840 
  6*94 
  annual 
  increase 
  of 
  south 
  inclination. 
  

  

  1841 
  „ 
  1846 
  5-45 
  

  

  1843 
  „ 
  1854 
  5-10 
  

  

  1854 
  „ 
  1873 
  5-20 
  

  

  1873 
  „ 
  1890 
  4-90 
  

  

  1890 
  „ 
  1900 
  7-80 
  

  

  