presidext's address. 19 



varied condition 100 years ago to compare with what exists to-day, 

 it is obvious that the Botanical Sux'vey will in time throw light 

 on many obscure questions of distribution and their connection 

 with changed conditions of all kinds." Xo doubt much evidence 

 of this sort is to be found in the botanical literature, but I am 

 only able to mention two instances. In a paper read before this 

 Association in 1916 Mr. J. S. Henkel describes the extension of 

 forest over certain areas in the Drakensberg and ascribes it at 

 least in part to protection from fire.^* In his presidential address 

 to Section C in 1920 Dr. T. E. Sim shows that in the limiting 

 region between Karroo and grass-veld the former is gaining, on 

 account of injudicious use of the veld and possiblj^ also on account 

 of drier climatic conditions." The former is a known cause, but 

 the latter is not yet proved as regards the actual amount of 

 rainfall. 



Historical Evidence. 



The written history of the interior of South Africa goes back 

 less than 300 years; the details recorded at an early date about 

 its climate and water supply are naturally meagre, and the condi- 

 tions then prevailing have generally to be surmised from incidents 

 of travel such as the facilities of obtaining water and grazing for 

 animals. Occasionally we find a considered statement about the 

 conditions of the country from the point of view of a Government 

 desirous of increasing the white population ; a valuable statement 

 of this kind is that of Commissary General de Mist in 1801, who 

 said that on a journey from the Olifants' River in the west to the 

 district of Graaff Reinet the line of country traversed would be 

 found to consist of a series of barren deserts and Karroo on which 

 not a morsel of food could be found for man or beast, and that 

 the more valuable country to the east wa-s already occupied by 

 natives.'" De Mist would no doubt be surprised at the farming 

 now done from Van Rhyns Dorp eastward to Middelburg, but 

 his opinion is evidence that the country he mentions had the 

 same kind of climate 120 years ago as it has to-day. 



A general statement of later date, concerning the character 

 of the country granted to the Albany Settlers, is quoted by George 

 Thompson ■,^^ it is pointed out that uncertain rains in the east 

 as compared with the west rendered the district chosen unsuited 

 to the 100 acre allotments made to the poorer class of settlers. 



The diary of Simon van der Stel's journey to Koperberg in 

 1685 gives a very good account of the facilities of travelling in 

 the western districts of the Cape ; the barren nature of the 

 country in what is now called the Harde Veld, which is rather 

 surprising as the journey was made in September, when the veld 

 is generally in good condition now; the frequent finding of brak 

 or salt water and the scarcity of fresh ; the description of the 

 small spring at the Koperberg itself and the dry river beds, just 

 as we find to-day ; and the drying up of various small waters 

 before the return journey in November, when they had to dig 

 for water in Buff el's River, where in October they had found 



