Anticyclones and S.A. Weather. 57 



The rainfall of the Port Nolloth division is the smallest 

 of all the Cape Colony divisions, viz., under 10 ins. a year. The 

 Damara-Namaqua Plateau of German S.W. Africa is over 4000 ft. 

 above sea level. Its mean annual rainfall is 3 to 10 inches, and the 

 station with the least percentage of cloud in South Africa is Spring- 

 bokfontein in Namaqualand, with only 16.9 per cent. 



In the Cape Report for 1901, pp. 183-4, Mr. Stewart has given 

 us a paper on the "Hot Winds of Namaqualand," and has shown that 

 in the months of June, July, and August, 1900, the East wind was 

 the prevalent wind, while from October to March the South was the 

 most frequent. In 1901 winter is reported to have set in at the end 

 of May, and strong, dry and cold East winds followed in June. 

 Mr. Stewart is led to account for the hot east winds by placing an 

 anti-cyclone over the interior of South Africa, and a cyclonic system 

 sea-wards. 



All the facts above recorded support the view that I wish to 

 advocate as a first approximation to the truth, and as a working 

 hypothesis, that the core of the Atlantic system has during recent 

 years been passing across Namaqualand along Lats. 26°-2 7° S., and 

 has then gone slightly N.E., so as to reach the Kalahari region about 

 April. From the Cape reports 1898- 1902 the rainfall during those 

 years was found to be a minimum over the area lying from Lat. 23° 

 S. to Lat. 28°-30 S., which points to the core passing approximately 

 along Lats. 26°-27° S., or some 3° to the North of Port Nolloth. 

 Following the path eastwards from Beersheba in Great Namaqualand, 

 we find from observations made at Morokweng in Bechuanaland in 

 1898, that there was practically no rain from April to October, or 

 somewhat less during these months than fell at Vryburg, Taungs, or 

 Maf eking. In 1899 the records from April to September show the 

 same thing, and a remark that horse-sickness still continued there in 

 April, but was over in May, shows that fros-s had begun in the 

 latter month. 



The District of Vryburg, Taungs, and Mafeking is, on the whole, 

 the driest during winter of which we have records, the mean fall for 

 the 6 months being Vryburg 3.85ins. and Mafeking 3.57ins. The 

 Mafeking records from 1888 to 1904 show that little or no rain falls 

 from April to October inclusive. And this brings us to the Transvaal, 

 in which we are now fortunate in possessing an excellent 

 Meteorological Observatory, with 290 Rainfall stations, and nearly 

 300 observers. Twenty-seven stations contribute barometer records. 

 By the courtesy of the Director of the Meteorological Department, 

 Mr. R. T. A. Innes, and thanks to the information afforded bv him, I 

 am able to give you (Appendices I. -IV.) the first charts that have been 

 made of the isobars over the Transvaal. They are for the four 

 months February, May, August, and November, and are based upon 

 the four official charts for the same months issued by the 

 Meteorological Council in 1887 for South Africa. They must be 

 considered as provisional only, but they will prove of great assistance 

 to anyone who wishes to test the views that have been advanced in this 

 paper, or to follow them up till they have been proved or disproved. 



