Notices of Memoirs — Dr. Johnston- Lavis on Vesiwins. 513 



It is also physically identical with the valuable iron ore worked 

 for many years at Westbury in Wiltshire, where it is met with at 

 a lower horizon, being there separated from the Corallian limestones 

 by 4 feet of marls and sands. 



This stratum, although probably of purely local origin, is to be 

 looked for in the beds above the Corallian throughout the whole of 

 Southern England, from Dorset eastwards. Its discovery at Dover 

 is only second in importance to that of the South-eastei-n Coal- 

 field. It will have to be taken into account in the future develop- 

 ment of the Coal-fields in Southern England. 



V. — The Volcanic Phenomena of Vesuvius and its Neigh- 

 bourhood. Eeport of the Committee, consisting of Mr. H. 

 Bauerman, Mr. F. W. Kudler, Mr. J. J. H. Teall, and Prof. 

 H, J. Johnston-Lavis. (Drawn up by Prof. H. J. Johnston- 

 Lavis.) 



SINCE the last report lava has continued to pour forth from the 

 top of the new lava-cone in the Atrio del Cavallo, sometimes 

 in small quantities, at others in considerable abundance. On no 

 occasion, however, did the lava issue beyond the limits that it 

 had reached in the years 1891-92. In fact, the whole of that 

 eastern part of the Atrio known as the Val d'Inferno has not been 

 invaded at all by the new lava during or since its issue in the spring 

 of 1891. The consequence of this has been that it has continued to 

 pile itself up around the line of fissure by which it issued, and still 

 further add to the dimensions of the great lava-cone that it had built 

 up in the Atrio. So great has this cone become that it constitutes 

 a prominent feature in the outline of the volcano as seen from 

 Naples. The eminence of Somma is separated from Vesuvius by 

 the depression of the Atrio. This notch, so to speak, in the general 

 outline was terminated below by an almost horizontal line, which is 

 now replaced by an obtuse cone, so that many people speak of three 

 summits to the Vesuvian volcano. This is rather an exaggeration, 

 for although the new lava-cone is of very considerable dimensions, 

 for the time occupied in its growth, yet it cannot compare with 

 that of the cone of Vesuvius on one side or the ridge of Somma on 

 the other. 



The whole of this new cone is entirely built up of lava, by far 

 the greater part being of the pahoehoe or corded type ; only now and 

 then, during marked activity, has there been produced any lava with 

 a rugged scoriaceous surface. The occasion was therefore a very 

 valuable one to determine the slope of such a lava-cone. This was 

 done only normally to the line of fissure by which the lava issued, 

 and which makes the cone terminate in an elongated ridge rather 

 than in a point. Practically all these clinometric observations, which 

 were taken with great care, gave angles varying from 13° to 15°. 



Comparing this angle with that of such mountains as Etna or 

 Mauna Loa we must consider that both are composite cones, and 

 have experienced many disturbing influences, such as the formation of 

 parasitic eruptive outlets, from which lava streams have issued far 



decade IV. VOL. I. NO. XI. 33 



