MR. A. W. RUCKER AND DR. T. E. THORPE ON A MAGNETIC 
Re.suIts of the Observations and Descriptions of Stations. 
Calculation of the Isomagnetic Lines. 
The Isogonal Lines. 
Data for the Calculation of the District Lines . . - . 
Declinations Calculated from the District Lines. 
Equations to Terrestrial Isogonals. . 
Declinations Calculated from Tei'restrial Isogonals. 
Calculated and Observed Values at Central Stations. 
Comparison of District and Terrestrial Isogonals. 
Lines of Equal Horizontal Force. 
Data for the Calculation of the District Lines. 
Horizontal Forces Calculated from the District Lines. 
Equations to Terrestrial Lines of Equal Horizontal Force. 
Horizontal Forces Calculated from Terrestrial Lines. 
Calculated and Observed Values at Central Stations. 
Comparison of District and Terrestrial Lines. 
Isoclinal Lines. 
Data for the Calculation of the District Lines. 
Equations to Tei'restrial Isoclinal Lines. 
Dips Calculated from the District Lines. 
Dips Calculated from Terrestrial Lines. 
Calculated and Observed Values at Central Stations. 
Comparison of District and Terrestrial Inncs. 
Local and Regional Disturbances Deduced from the 1891 Survey.. • 
Comparison with 1886 Survey. 
Secular Change between 1886 and 1891. 
(1) Deduced from Central Stations. 
(2) Deduced from Rejieat Stations. 
(3) From Magnetic Observatories.. 
Table of Secular Change. 
Comparison with Observations. 
Comparison with Conclusions in 1890 Memoir. 
Reduction of the Observations of the 1886 Survey to the Epoch of the New Survey . 
Comparison between the Tei'restrial Isomagnetics Obtained from the two Surveys of 
1886 and 1891 when Reduced to the same Epoch. 
Final Tables of Calculated Values of the Magnetic Elements for January 1, 1891, 
Deduced from Both Surveys. 
Comparison of the Vei'tical Force Disturbances at the Repeat Stations as Deduced from 
the Two Surveys. 
Similar Comparison of the Directions of the Horizontal Disturbing Forces. 
Comparison of the Isomagnetics Deduced from the 1891 Survey, and from the j\lean of 
the 1886 and 1891 Surveys respectively.. 
Local and Regional Disturbances. 
Table of Declinations, Inclinations, Horizontal and Vertical Forces Observed and 
Calculated with Dih'erences. 
Local and Regional Disturbing Forces Obtained from the two Surveys Separately and 
Combined. . 
Table of the same. 
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