Besults of further Experiments on Table Mountain. 105 



observations on their occurrence on the Zwartebergen, kindly made 

 at my request by the Eev. J. Whaits at Prince Albert during the 

 summer of 1904. This list will show how numerous the cloudy days 

 are on those mountains, and of what importance these clouds must 

 be to the water supply of the streams rising in these and other 

 ranges of South-Western Africa. 



It is interesting to see that a view quite similar to that which 

 I hold concerning the important function of the vegetation on our 

 mountains in connection with the water supply of the springs has been 

 expressed by such an eminent authority as Professor Cleveland Abbe, 

 of the Weather Bureau of the United States Department of Agricul- 

 ture, with regard to the Island of Ascension. The principal water 

 supply of the Naval Station on the island comes from the summit of 

 Green Mountain, which is several miles away. The upper portion 

 of the mountain is covered with vegetation, and nearly all the water 

 on the summit comes from slight showers and the steady dripping 

 from trees which are enveloped in the clouds. These trees simply 

 mechanically collect the water-drops which are produced from the 

 condensation of the water vapour in the ascending cooling air. 



In conclusion, I wish to point out once more, that I do not consider 

 the measurements given in these communications to represent real 

 rainfall. In my previous paper a quantity of 75 inches was men- 

 tioned for a certain period, and the Table on page 102 of this paper 

 shows a record of 48 inches for one month. Even if we discard 

 90 per cent, of these quantities, the remaining one-tenth is still so 

 largely in excess of the rainfall recorded in the ordinary gauge, that 

 I think even the most sceptical critic will recognise, that this quan- 

 tity of water, gathered during the dry season of the year, must 

 exercise a considerable influence on the vegetation of the moun- 

 tains, as well as on the springs. 



