246 TRANSACTIONS OF SOCIETIES. 



Geological Society of South Africa. — Monday, January 20th : Mr. 

 H. S. Harger, President, in the chair. — " Some features associated with 

 the denudation of the South African continent" (Presidential address): . 

 H. S. Harger. In order that the vast extent of denudation to which the 

 subcontinent has been subjected might be fully grasped, the first portion 

 of the address was devoted to a description of the configuration of South 

 Africa at the close of the Karroo period — that of a huge table land, 

 varying in altitude between 8,000 and 13.000 feet above sea level. In 

 Jurassic times the Karroo sediments had reached an altitude of fully 

 8.000 feet (resulting from the degradation of a vast unknown area) when 

 the great volcanic outbursts of the Drakensberg piled about 5,000 feet of 

 basic lavas over the southern portion of the continent. After the close 

 of the Karroo period and cessation of igneous activity, an era of continuous 

 denudation ensued, and in the course of ages the huge peneplain was dis- 

 sected downwards by rivers which have cut through ranges to depths of 

 3,000 feet, or carved through at least 1,000 feet of hard dolomite and 

 diabase. During the earlier stages of denudation the country passed 

 through much heavier rainfall than is now experienced, and river beds 

 now perennially dry have banks fifty feet high and are strewn with 

 boulders of considerable size. In addition to aqueous denudation, wind 

 erosion has in some places carved great valleys out of the rock formations, 

 and scarified not only basalt dykes but even quartz, jasper, agate, and 

 chalcedony. Incidentally the author expressed the view that millions of 

 diamonds from the upper Kimberlite occurrences must have been carried 

 into the Atlantic, not only by the Orange River, but also into the ocean 

 facing Luderitzland by other rivers which have ceased to exist. 



Monday, February 24th : A. L. Hall, B.A., F.G.S., President, in the 

 chair. — "' Structural features of the Western Witwatersrand " : Dr. E. T. 

 Mel lor. A comprehensive description of the geology of the country 

 extending westward from the neighbourhood of Roodepoort as far as the 

 furthest outcrops of the Witwatersrand System in that direction which can be 

 directly connected, with the main Witwatersrand area, including the whole 

 of the West Rand, extending south-westwards as far as the neighbourhood 

 of Bank, on the Potchefstroom railway line, and embracing an area of over 

 400 square miles. 



South African Institute of Electrical Engineers. — Thursday, 

 February 20th: Mr. J. W. Kirkland. President, in the chair. — "Notes on 

 three-phase winding equipments " : L. B. Woodworth. In view of the 

 interdependence of the various items constituting the chain of the winding 

 system, various points were mentioned to which attention should be 

 given in the design and installation of feeder, main control and reversing 

 switches, in the regular and systematic inspection of contacts, operating 

 and trip gear, and in the testing, frequent cleaning, and changing of oil. 

 Recommendations were made regarding the type of switch gear to be 

 employed for solution and circulating pump motors, the provision and 

 arrangement^ of terminal panels, the range of overload trips on 

 feeder and main control panels, the location of the electrically-operated 

 over-winding device. The rotor circuit was then more fully discussed, and 

 the question of static dischargers considered in this connection, particular 

 attention being given to the occurrence of flash-overs at various points. 



Cape Chemical Society. — Friday, February 28th: Dr. C. F. Juritz, 

 M.A.. F.I.C., President, in the chair. — " Determination of nicotine Jn 

 tobacco and tobacco extracts " : Prof. P. D. Hahn. A series of deter- 

 minations made by the distillation method yielded results differing very 

 considerably from those obtained when the nicotine was extracted by 

 means of ether, and it was suggested that other substances than nicotine 

 were dissolved out when the ether extraction method was employed, and 

 thus the proportion of nicotine was made to appear higher than it actually 

 was. — " Note on the occurrence of Tantalite and Columbite " : Prof. P. D. 

 Hahn. Descriptions ( with analytical results ) were given of minerals 

 occurring in the north-west of the Cape Province, near the Orange River 

 mouth. 



