ON THE VOLCANIC PHENOMENA OF VESUVIUS. 



319 



ereab cone it again assumes nearly the same azimuth as at starting, an 

 arrano'emeut winch is quite evident when the Vesuvian cone is regarded 

 from the Punta del Nasone. From that, the highest point of Somma, 

 the lower extremity of the rift lies a little to the right or west, and faces 

 that part of the Sonima ridge which corresponds to the upper extremity 

 of the Vallone Cancherone. 



In the forenoon of June 30 much dust had fallen at the lower railway 



YiG. i. — Plan of the summit of the great cone of Vesuvius, July 31, 1891. 



Limits of the crater of 1872 ; where overflowed by more recent lavas, a, and where 

 still uncovered, a' ; remains of cone of 1885-86, b ; jiart of crater edge of 

 May 1886, c ; part of crater edge nf May 1889, d ; cone of eruption up to 

 June 7, 1891, ef; fissure of May 1889. jr; "yellow patches of decompo.'*ed lava, 

 scoriae, and dust, h ; lissures emitting hot vapour with HCl, i; guides' 

 shelter, y; numerous fissures at the S.E. edge of the crater plain and great 

 cone that the preceding days had increased in size and number, k ; other 

 fissures on the N.E. of great "cone, I ; fissures along the edges of the crater in 

 process of formation, »« ; present crater, u ; dykes seen in section, o ; hoi ow 

 dyke of the eruption of May, 1889-91, and ot anterior ones, p ; same of erup- 

 tion of May 2, 1885, q ; vapour column hiding bottom oi crater, r; fissure 

 of eruption of June 7, 1891, x. 



station, of which we collected some bagfuls. It is the usual fine sandy 

 material of these eraptions, and consists of the pulverised components of 

 the cone of eruption. 



Having passed the night at the lower railway station, the next day we 

 crossed the Atrio, ascended to the western extremity of the ridge of 

 Somma, and followed it along so as to get a general bird's-eye view of 

 the whole scene of the eruption, and take photographs of the more 

 important points. As one stands on the Punta del Nasone and embi-acea 



