Proceedings of the SoutJi African Philosox>hical Society. Ixxxi 



was interrupted for several days. On this assumption the time of 

 passage would be 18 days, which, though 5f days longer than the 

 average, is 2 or 3 days within the maximum period within which 

 such a storm might be expected to reach here. The success of this 

 warning renders the subject one which should be pursued further in 

 view of the importance of storm warnings, particularly to the 

 shipping and farming community. 



Mr. A. W. EoGEES, F.G.S., gave an exhibition of lantern slides 

 illustrating some of the recent work of the Geological Survey. 



The slides were prepared from photographs selected from the 

 collection made during the past three years by the field geologists of 

 the survey. Five views illustrated the types of country occupied by 

 the ancient (Pre-Table Mountain sandstone) rocks of Prieska and 

 Van Ehyn's Dorp. The occurrences of the Table Mountain sand- 

 stone in the divisions of Clanwilliam and Van Ehyn's Dorp and in 

 Pondoland, were depicted in several slides, which showed the simi- 

 larity of the country formed by that rock in these far distant parts of 

 Cape Colony. The views taken in Clanwilliam and Van Ehyn's 

 Dorp also demonstrated the fact that the Table Mountain sandstone 

 thins out northwards from the Cedarbergen, and that the thickness 

 of rock separating the denuded surface of the Pre-Table Mountain 

 sandstone rocks from the Dwyka Conglomerate constantly diminishes 

 in the same direction, a state of things due to the denudation of the 

 Witteberg, Bokkeveld, and Table Mountain sandstone groups before 

 the deposition of the Dwyka Conglomerate. The succession of rocks 

 from the Table Mountain sandstone to the Witteberg in the country 

 east of the Cedarbergen was shown in several slides. The charac- 

 teristic features of the Dwyka Conglomerate, and the glaciated 

 surface of the underlying rocks in the neighbourhood of Prieska, 

 were shown in many slides, and for the sake of comparison a view of 

 the Conglomerate as it occurs near Karroo Poort was thrown upon 

 the screen. The rest of the slides illustrated the rocks above the 

 Ecca Beds. An interesting comparison between the dry Karroo 

 type of country, composed of sedimentary rocks of Karroo age and 

 intrusive dolomite, and the well-watered district in Pondoland 

 formed by the same rocks, was made by throwing upon the screen 

 several views taken in the two districts. The two last views were 

 illustrations of the Cretaceous rocks of eastern Pondoland, and the 

 consolidated sand-dunes of Bredasdorp. 



Professor J. C. Beattie read some " Observations of Atmospheric 

 Electricity at Cape Town," by W. H. Logeman, Esq., B.A. 



