Geological Society. 151 



editions the new matter should be worked up in such a manner as to 

 become capable of being incorporated with the older portion of the 

 book, to maintain homogeneity of treatment. One cannot help 

 feeling, for instance, in reading the practical hints on the ballistic 

 method of measurement contained in the last chapter, that the 

 most logical arrangement would have been to append these hints 

 to the account of the ballistic method given in Chapter III. As 

 it is, a reader desirous of information regarding this method of 

 measurement naturally turns to Chapter III., and in the account 

 there given he fails to find what are — from the experimenter's 

 point of view — exceedingly useful practical hints, such, e.g., as 

 the one regarding the extreme convenience of using a ballistic 

 galvanometer of the D'Arsonval type. We trust that in future 

 editions this suggestion may be adopted. 



La Rivista Tecnica clelle Scienze, delle Arti applicate aW Industria e 

 delV Insegnamento Industricde. Anno I. Eascicolo 3-4. Editori 

 Roux e Viarengo : Torino. 

 This very readable periodical contains a number of interesting 

 articles dealing with various technical and scientific subjects. The 

 first article is devoted to a discussion of alternating currents : 

 this is followed by another in which the scientific foundations of 

 electro-chemistry are dealt with. Next comes one on the subject 

 of toothed gearing, and the remaining articles deal with a large 

 variety of topics interesting from an industrial standpoint. Most 

 of the articles are well illustrated, and are not too technical to 

 be beyond the understanding of a reader with a moderate 

 knowledge of the practical applications of science. The new 

 periodical should appeal to a wide circle of readers. 



X. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 

 [Continued from vol. 1. p. 670.] 

 December 1.9th, 1900.— J. J. H. Teall, Esq., M.A., F.R.S., 

 President, in the Chair. 



r PHE following communications were read : — 

 *- 1. ' On the Igneous Rocks associated with the Cambrian Beds 

 of the Malvern Hills.' By Prof. T. T. Groom, M.A., D.Sc, F.G.S. 



The Cambrian beds of the Southern Malverns are associated with 

 a series of igneous rocks which have commonly been regarded as 

 volcanic, but are probably all intrusive. They consist of a series 

 of bosses, dykes, sills, and small laccolites intruded into the Upper 

 Cambrian Shales and into the Hollybush Sandstone. The dykes 

 appear to be confined to the sandstones, the sills and laccolites 

 chiefly to the shales, while the bosses are found in both. The rocks 

 consist of a series of ophitic olivine-diabases, a related series of 

 porphyritic olivine-basalts, and a series of porphyritic amphibole- 

 bearing rocks of andesitic habit, but probably to be classed with 



