The Eruption of Mount Vesuvius 



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or more degrees, covered with hot sand 

 and broken rock fragments, terminated 

 about 1 20 feet (vertically) below by 

 jutting ledges which appeared to be 

 precipitous. Beyond was steam and sul- 

 phurous heat and obscurity. The ledges 

 fumed in places. No noise could be 

 heard above the howling of the wind. 

 The curvature of the crater edge was 

 irregular with embayments, and it 

 showed much irregularity in height. We 

 could not see the opposite side of the 

 cauldron, but from the curvature it was 

 estimated that the crater could not be less 

 than from one-fourth to one-half mile in 

 diameter — unusually large for Vesuvius. 

 The summit was 4,000 feet above the sea 

 by Aneroid, or some 350 feet lower than 

 before the eruption, according to the 

 data furnished us by the officers of the 

 observatory. The east-west diameter is 

 much greater than the north-south. The 

 depth of the crater is at least 150 feet and 

 no one knows how much more. There is 

 a great notch or caving-in on the north- 

 east rim of the crater, where thousands 

 of tons of gravel and sand were hurled 

 clear over the crest of Monte Somma 

 and fell on Ottajano and San Giuseppe 

 with most disastrous results. On the 

 south side of the cave, toward Boscotre- 

 case, a radial rift opened, letting lava 

 escape from different elevations progres- 

 sively, lower until finally the great out- 

 flow came from a mouth or "bocca" only 

 2,000 feet above tidewater, half way 

 down the mountain, and quite below the 

 cone proper. 



The history of the eruption, as gleaned 

 from the accounts of men of science who 

 were on the spot, is briefly as follows : 

 In 1904 there was a lava flow which 

 stopped in September of that year. In 

 May, 1905. lava flowed from a split in 

 the northwest side of the cone and con- 

 tinued in active motion throughout the 

 year. It ceased flowing at the time when 

 the present eruption opened a new vent 

 on the south side of the cone. On April 



4. [906, a splendid black "cauliflower" 

 cloud rose from the crater. On April 4, 



5, 6, and 7 lava mouths opened along the 



southern rift above mentioned, first 500 

 feet below the summit, then 1,300 feet 

 lower, and finally 600 feet lower still, all 

 in the same radial line. The lowest 

 mouth was more than half way down the 

 mountain, and from this orifice came the 

 destructive streams. It should be borne 

 in mind that these flows are not floods of 

 lava which cover the whole slope of the 

 mountain, but relatively narrow snake- 

 like trickles, none the less deadly when 

 they push their way through a closely 

 built town. The molten rock crusted 

 over and cracked, making a tumble of 

 porous boulders at its front. 



At 8 p. m., April 7, a column of dust- 

 laden steam shot up four miles from the 

 crater vertically. The cloud snapped with 

 incessant lightnings. New lava mouths 

 opened and the flows moved forward, 

 crushing and burning and swallowing 

 parts of Boscotrecase, the stream forking 

 so as to spare some portions of the town. 

 Meantime torrents of ashes fell on Otta- 

 jano on the opposite side of the volcano, 

 and many roofs collapsed and lives were 

 lost. At the observatory Dr Matteuci 

 and his colleagues were obliged to re- 

 treat, as the observatory was rocking 

 violently and heavy stones were falling. 



They went only half way down the 

 mountain, however, and returned to their 

 posts next day. The observatory was 

 uninjured, although stones had fallen 

 weighing as much as five pounds. The 

 stones and sand of the eruption are 

 mostly composed of ancient lavas broken 

 up by the steam blast. On April 8 the 

 electrical dust cloud still hung over the 

 volcano, but thereafter through a fort- 

 night the explosions diminished in vio- 

 lence until only quiet steam rose. On the 

 1 8th bad gases were blown downward on 

 the observatory by a strong southeast 

 wind, and some persons nearly lost their 

 lives by asphyxiation. The gases were 

 probably both carbon dioxide and sul- 

 phuretted hydrogen. 



Boscotrecase was ruined wholly by 

 lava; Ottajano by falling gravel. Bosco- 

 trecase is traversed in two places by the 

 clinkery lava stream and in some cases 



