﻿156 



to extend the direction of the magnetic meridian, as indicated by the observations, towards the South 

 Magnetic Pole. 



The result of his work is shown on Chart No. 2, where it will be seen that these lines of direction 

 intersect within a space triangular in form (Plate 18). 



The radius of the circle inscribed in the triangle measures about 38 geographical miles, and the centre 

 of the circle indicates the probable position of the pole, and is in latitude 72° 50' S., longitude 156° 20' E. 



Determination of the Position of the Magnetic Pole by Means of the Inclination 



Results. 



All the Inclination results were plotted on a chart, and lines of equal Inclination drawn (Chart No. 3), 

 from a consideration of which the prol>able position of the pole is indicated to be in latitude 72° 52' S., 

 longitude 156° 30' E. The agreement between this position and that determined by the Declination 

 results is remarkable, and may be considered as corroboration of the results. 



The mean of the two positions, viz., latitude 72° 51' S., longitude 156° 25' E., is in all probability a 

 close indication of the centre of the polar area (Plate 19). 



SECTION XIV. 



Comparison of Results with those given by General Sabine. 



Total Force. 



In Sabine's chart of lines of Total Force the highest value for which a line is drawn is that of 15 B.U. 

 (= 0'6916 c.g.s.). This line passes outside all the positions at which observations were made during the 

 1902-1904 expedition. 



The observation position nearest to Sabine's line is that in latitude 79° 32' S., longitude 176° 1' E., 

 during the south-eastern sledge journey by Mr. Bernacchl 



The result of this observation gives the value of Total Force = • 6896 c.g.s. 



The change of intensity thus indicated is very small. 



, ' Declination. 



To compare the Declination as given on Sabine's chart with present results, the values were obtained 

 from the respective charts at the positions given in the following table : — 



Table XX. 



The change indicated at McMurdo Sound, viz., 23° 45' in 62 years, gives a mean aimual increase of 23'. 

 The yearly difference as derived from the absolute oliservation diagrams (Section IV. for 1902-1903) 

 shows a decrease of 26'. 



