672 Transactione of the Royal Society of South Africa. 
there are only three repeats — one at Bulawayo, one at the Victoria Falls, and 
one at Beira. Between longitudes 28° E. and 34° E., and north of latitude 
24° S., it was not found convenient to reoccupy a station. In Damaraland 
no station has been reoccupied. In these two regions the reductions applied 
leave something to be desired. 
In the 1903 maps no results, except in the extreme south, were given for 
the Cape Province west of 20° E., and none west of 25° E. in the country 
north of the Orange Eiver. In the present maps results are given for 
practically all the region south of the Orange Eiver, a considerable part of 
Damaraland, a region extending from the Orange River to the Molopo, and 
from 25° E. to 23° E. In addition, the declination and the dip are given for 
a considerable number of additional stations in the Orange Free State, the 
Western Transvaal, and the Cape Colony. 
The declination, which is westerly (Map I), show throughout a decrease. 
In the south-west, in the neighbourhood of Cape Town, the decrease amounts 
to roughly a degree and a half in ten years. On the eastern coast, from 
East London to Durban and Beira, the change is as much as two degrees in 
the same period. Thus in the 1903 map the 28° 30' isogonic occupies roughly 
the same position as the 27° line in the present map. The 25° isogonic in 
the 1913 map passes close to Port Alfred and inland through G-raaff Reinet,. 
following approximately the direction of the 27° line in the earlier map. 
Farther inland the lines open outwards more than was the case at the 
previous epoch, the result of a small secular change towards the north. 
The greatest anomalies in the declination are shown at G-lenallen, where 
the magnet points about 20° more west than is to be expected there, and at 
Bretby, where the anomaly is about 12°. Both these stations are in regions 
where magnetic ores are present. There are other smaller anomalies in 
various parts, particularly in the East Transvaal and in the district around 
Gemsbokfontein, Britstown, De Aar, and Nelspoort. Additional stations 
in this region will probably throw considerable light on the disturbance 
which undoubtedly exists. 
The southerly (Map II) dip has increased in the period 1903-1913. In 
the 1903 map the 62° S. isoclinal just appears at Port St. Johns ; in 1913 the 
dip at that place is 62° 59'. The increase in the east is between 50' and 60' 
in the ten years. At Cape Town the increase in the same period has been 
between 80' and 90'. The most striking anomaly is again at Grienallen, 
where the southerly dip is approximately 15° less than the mean value for that 
neighbourhood. The other anomalies are small and particularly numerous 
in the East Transvaal. 
