Secular Variation of the Magnetic Elements. 
183 
Gauss-Carnegie observations. The annual changes recorded in this paper 
vary from an average decrease of l'-5 of westerly declination at Mauritius 
during the period 1900-1909, a change v^hich was turned into an increase 
of 1''4 per year of westerly declination between 1907 and 1909, to an 
annual decrease of about 14' in the neighbourhood of Durban. If we go 
in a north-westerly direction from the latter place the annual decrease 
becomes less, and falls to 5' at Loanda. The decrease in the absolute 
value of the change is quite definite, though not so great as we go west 
or indeed in any direction other than seaward from this centre of greatest 
change. 
A further interesting conclusion which can be drawn from the table 
is that at the present day the absolute value of the change is increasing 
at all stations ; the lines of equal annual change appear to be moving 
inland in an approximately westerly direction. This will be evident from 
msf dec/ins f ion. 
Fig. 1. 
the consideration of the results at the following places : At Beaufort 
West the mean decrease between 1900 and 1912 is 8'*2 per year, between 
1905 and 1912 it is 10'-8 ; at Cape Town between 1901 and 1914 the 
mean decrease is 8'-l, between 1909 and 1914 it is 9'*7 ; at Cradock the 
mean change between 1900 and 1913 is ll'*2, between 1908 and 1913 it is 
13'*8 ; at Hutchinson the mean change between 1900 and 1913 is 9''3, 
between 1908 and 1913 it is ll'-O; at lilovo Eiver between 1903 and 1913 
it is 14'-6, between 1908 and 1913 it is 15'-6 ; Matjesfontein has a mean 
change between 1900 and 1913 of 8'-9, and ll'-O between 1908 and 1913 ; 
Newcastle has a mean change of 9'"4 between 1903 and 1913, which 
increases to 14'-6 between 1908 and 1913. 
In Fig. 1 the change in declination is shown for the whole period at a 
number of places. 
The results for the dip are shown in Plate II. The greatest annual 
