Intelligence and Miscellaneous Articles. 71 



M. Bigot). These have been correlated with others near Cher- 

 bourg, and described as underlying the " gres Armoricain." The 

 Alderney grits, therefore, form part of a series which can be traced 

 over 30 miles, and which belongs to the Upper Cambrian (of Lap- 

 worth). 



Remarks were made on the Jersey conglomerates (Ansted's con- 

 jectural identification of these with the Alderney grits being ap- 

 proved), on the resulting evidence that the Jersey rhyolites are not 

 Permian, but Cambrian at the latest, on the still earlier age of the 

 Guernsey syenites and diorites, and on the antiquity of the 

 Guernsey gneisses. 



2. " On the Ashprington Volcanic Series of South Devon." By 

 the late Arthur Champernowne, Esq., M.A., E.G.S. 



The author described the general characters of the volcanic rocks 

 that occupy a considerable area of the country around Ashprington, 

 near Totnes. They comprise tuffs and lavas, the latter being some- 

 times amj-gdaloidal and sometimes flaggy and aphanitic. The 

 aphanitic rocks approach in character the porphyrinic " schalsteins " 

 of Nassau. Some of the rocks are much altered : the felspars are 

 blurred, as if changing to saussurite, like the felspars in the Lizard 

 gabbros. In other cases greenish aphanitic rocks have, by the de- 

 composition of magnetite or ilmenite, become raddled and earthy in 

 appearance, so as to resemble tuffs. The beds are clearly inter- 

 calated in the Devonian group of rocks, and the term Ashprington 

 Series is applied to them by the author. Although this series pro- 

 bably contains some detrital beds, there are no true grits in it. 

 Stratigraphically the series appears to come between the Great 

 Devon Limestone and the Cockington Beds, the evidence not being 

 discussed by the author, however, so fully as he had intended, as 

 the paper was not completed. 



X. Intelligence and Miscellaneous Articles. 



ON A POSSIBLE GEOLOGICAL ORIGIN OF TERRESTRIAL MAGNE- 

 TISM. BY PROFESSOR EDWARD HULL, M.A., LL.D., F.R.S., 

 DIRECTOR OF THE GEOLOGICAL SURVEY OF IRELAND.* 



rpHE author commenced by pointing out that the origin and cause 

 -*- of terrestrial magnetism were still subjects of controversy 

 amongst physicists ; and this paper was intended to show that the 

 earth itself contains within its crust a source to which these 

 phenomena may be traced, as hinted at by Grilburt, Biot, and 

 others ; though, owing to the want of evidence regarding the 

 physical structure of our globe in the time of these observers, 

 they were unable to identify the earth's supposed internal 

 magnet. 



The author then proceeded to show cause for believing that 

 there exists beneath the crust an outer and inner envelope or 



* Communicated by the Author, being an Abstract of a paper commu- 

 nicated to the "Royal Society, 10 May, 1889. 



