Intelligence and Miscellaneous Articles. 159 



sion. Amongst the results of a comparison of the Thiiringian and 

 Swabian types with those near Wurzburg is the discovery of the 

 fauna of Recoaro and Mickelschiitz in the Middle Wellenkalk ; and 

 the author remarks that as the rocks of the Alpine so-called Mus- 

 chelkalk entirely agree with the Wellenkalk of his district, that 

 rock ought henceforth to be called Wellenkalk ; for no representa- 

 tive of the true (Upper) Muschelkalk has hitherto been observed 

 in the Alps. 



The Jurassic rocks occurring in Baden he refers to the Cornbrash 

 and the Inferior Oolite. 



3. " On the Changes rendered necessary in the Geological Map 

 of South Africa, by recent discoveries of fossils." By Dr. R. N. 

 Rubidge, F.G.S. 



Dr. llubidge first called attention to a former paper, in which he 

 pointed out the occurrence of horizontal beds of sandstone resting 

 on the upturned edges of gneiss, and continuous with inclined sand- 

 stone of like kind interstratified with gneiss. He therefore conjec- 

 tured that the Clay-slate and Bokkeveldt schist, which Bain con- 

 sidered distinct, belonged to one formation, that they are of the 

 same age as the gneiss, and that the " Carboniferous rocks " of the 

 Eastern province were not separable from the Clay-slate which Mr. 

 Bain had called Primitive clay-slate. It follows from this, that if 

 the clay-slate proved Devonian, as Dr. Rubidge believed it would, 

 the horizontal quartzite must be much newer, and probably an out- 

 lying mass of the Dicynodon-rocks. He explained these phenomena 

 by supposing that rocks of widely different ages had been metamor- 

 phosed into masses having the same mineralogical characters. 



The discovery of certain fossils has lately verified the conjecture 

 respecting the Devonian age of the clay-slates and Bokkeveldt rocks ; 

 and Dr. Rubidge therefore infers that the rest of the old rocks are of 

 the same age. Finally, the discovery of a Calamite in the sand- 

 stone, not unlike some specimens belonging to the same genus 

 found in the Dicynodon-rocks, renders the probability of the truth 

 of the second conjecture very great. 



XX. Intelligence and Miscellaneous Articles. 



ON AN ELECTRICAL INDUCTION MACHINE* 

 BY M. HOLTZ. 



rpHE object of this apparatus is to excite by means of induction a 

 ■*■ greater quantity of electricity than that which exercises the indu- 

 cing action. In its simplest form it consists of a fixed glass disk, on 

 one side of which an even number of tinfoil sectors are pasted, which 

 receive from a small electrical machine alternately positive and nega- 

 tive electricity. In front of this disk, on the glass side, is a second 

 glass disk provided with the same number of tinfoil sectors, which is 



