344 



NATUJ^E 



[August 8, 1S95 



phenomena of the \olcano during the early months of the I 

 present year, and has recorded the changes in La .\>t/uri\ \ 

 June S ( Fig. l). It appears from his interesting descrip- 

 tion that in January of this year the apex of the cone of 

 eruption overtopped the edge of the 1S91 crater. Lava [ 

 even flowed out in the crescentic depression between 

 eruptive cone and crater ring. This was followed by a 

 little repose of some days, to be succeeded by powerful 

 ejections of lava cakes to a considerable height i8o to 100 

 m.i, which rapidly added to the growth of the erupti\e 

 cone. In May, this new cone was from 15 to 20 m. above 

 the 1891 crater, and at the commencement of July was 

 considerably more, as is shown by Fig. 2, taken I 

 from San (liorgio a Cremano, as the others- and ■ 

 also notes — by Mrs. T. R. Guppy.' This sketch shows 

 that on the day preceding the eruption, central activity 

 with cone-forming stage was vei-y active, attaining the 

 fifth degree on my scale. 



M. Bourdariat's plan of the summit of the great cone, 

 constructed on one of mine of earlier date, shows the axis | 

 of the new eruptive cone is not concentric, but to the nortli- 

 west of the 1S91 crater. This he attributed to the wind, 

 no doubt one of the causes at w ork, but 1 had seen such 

 displacement to be the case in November last, when from 

 the depth of the cone top within the enclosing crater walls 

 these sheltered the falling cakes from the wind. There 

 was evidently even then the radial fissure directed to the 

 north-west in process of formation, which has now been ' 

 the point of issue of this new eruption. | 





Fic. 2.— Vesuvius a.s seen from San (icorgio a Cremano before the eruption 

 (commencement of July). 



The first indication of the final splitting of the great 

 cone was at midnight, when the crater became quiet. In 

 half an hour that is, on July 3 at 12.30 o'clock— when 

 the guardian of the upper railway station of .Mr. G. M. 

 Cooks railroad, which is but a very short distance 

 from the rift, was awakened by a strong shock of 

 earthquake that produced some slight cr.uks in the 

 masonry foundation of the building. The shocks. 

 though slighter, continued during the night. .\t eight the 

 stronger shocks were again repeated, and the activity, 

 which had recommenced at the chimney, had again 

 ceased. This was due to the filling f)f the fissure as it 

 extended outwards by the lava, the level of the surface of 

 which naturally sunk. When this takes place, support 

 is removed from the inner sides of the chimney in the 

 cone, which crumbles in and chokes the vent. The whole 

 top of the mountain had by this lime become fissured, in 

 consequence of which, at nine o'clock, seven or eight 

 large blocks of rock, besides a quantity of small ones, 

 were detached from the top of the cone, crashed and 

 ploughed down its side, leaving a scar described as 

 looking like a mud stream, and marked by a number of 

 pits at equal distances, due to the bounding of some of 

 these boulders. This scar is seen in Fig. 3, close by the 



''''"■ Mr,, r.iipny tnt imtc^ iind 

 Y tM-. ttlated A\ my fliv[N>^.il. 



'■1 know, .'til the chiin^es o( 



*' ' ' •" ' ■"'•.: '"• ■Ti..',>, ,..,.- .rir rt.i. r.^i>l.:H in N.iplro. 



NO. 1345, VOL. 52] 



side of the right of the new lava stream. .Mr. Ticibcr, 

 Mr. Cook's engineer, calculates one of these blocks to be 

 at least 20 cm. The point of detachment and the re- 

 sulting scar was h\ the side of the upper part of the new 

 fissure, but a little to the south-west, and the traces left 

 by the rolling masses are parallel to it. 



.■\t 10.18, the radial dyke reached the surface of the great 

 cone and formed an eruptive mouth on a level with and 

 to the north of the upper railway station, from which a. 

 copious outflow of lava took place, running down the 

 cone, as seen in the figure below. 



.•\t 10.30, about 70 m. low cr dow n. a fresh erupti\ e mouth 

 was opened, and is well seen in Fig. 3, having an oblique 



f 



Fh;. 3. — Vesuvius as seen on July 3, .it 10 a,m. 



cralerifonn appearance, as in the case of the upper one, 

 and on other similar occasions a Jet of steam, that con- 

 stitutes the excavating agent, was converted into a blackish 

 column by the lapilLe, sand, and dust dislodged and 

 carried up with it from the side of the mountain. There 

 is certainly some discrepancy in Mr. Treiber's report, for 

 Mrs. Guppy's sketch, made at ten o'clock, shows this low er 

 docctt already in existence. Her sketch likewise exhibits 

 the progress of truncation of the central eruptive cone by 

 the formation within it of a crater. Such a crater is 

 entirely due to the crumbling in of the edges and their 

 fall down the chimney, as no explosions were going on by 

 the top part of the main chimney. Lava continued to pour 

 forth from ilie low er end of the low er craleret, and probably 

 from a part of the radial fissure that reached the surface 

 below it, IhiI which of course is hidden by the flowing 

 lava. The stream reached the bottom of the g^e,^t com.- 

 at the junction of the .Vtrio del Cavallo and the I'iano di 

 Genista, and then extended towards the upper end of the 

 ridge of the Lion's Paw, or I Canteroni, where w as once 

 the old Crocelle. Here it soon formed a fine stream 60 m. 

 in bre.adth. Besides the two iiifiin craterets. already 



Vu.. 4 -Vcsuviun tu seen on July s, at 10 .i.m. 



described, two minor ones also were formed on the same 

 line of rift. 



< )n July 4. the craterets quieted down, little la\a flowcil, 

 so that during twenty-four hours the face of tlie stream 

 only .advanced 12 m. This corresponded with a slight 

 return of .activity at the main chimney, so as to relieve the 

 accumulating vapour tension of the lava below, wlili li ihe 

 mountain will not resist for long. 



The ejections w ere, of course, of the mci'ssory type thai 

 is, not csscii/ia/ to the eruption, but simply the remnants 

 of ihc ( rumhled-in porlion iif the eruptive cone. ICach 



