J. W. Judd — On Volcanos. 151 



nearly the same time, but quite independently, by the two geologists 

 who, in Germany and France respectively, have done more perhaps 

 than any others for the promotion of the study of volcanic phenomena, 

 more especially by combating errors, which in those countries so 

 long retarded its progress. I refer to Friedrich Hoffmann and 

 Constant Prevost. The former author has given us a detailed 

 account of his researches, and the latter has borne witness to its 

 substantial accuracy. 



Hoffmann remained for three weeks in Stromboli at the end of 

 1831 and the beginning of 1832 ; he on three different occasions 

 spent a considerable time on the edge of the crater, and minutely 

 describes what he witnessed. He was convinced both from what he 

 heard and saw, that the openings at the bottom of the crater vary in 

 size, number and condition from time to time ; shortly before his 

 visit there were no less than seven openings in the crater, but when 

 he examined it himself, there were but three : but these were seen to 

 be quite distinct from one another both in position and in the nature 

 of their action. 



The largest of the openings occupied the centre of the crater floor, 

 and gave forth vapours only, which produced yellow crusts on its 

 sides. To the south-west of this, on the same level with it, and 

 nearly under the crater-wall, another mouth about 20 feet in 

 diameter was seen, which discharged abundant white clouds, and gave 

 origin to constant smaller or greater explosions. In the interior of 

 the glowing red throat of this chimney, a fluid column of lava could 

 be seen moving up and down, and perhaps sinking to a depth of 20 

 or 30 feet below its summit. Through this column of liquid lava 

 bubbles of steam burst with a noise which resembled that of a fur- 

 nace when the door is opened ; the puffs taking place regularly at 

 intervals of about a second, and giving rise to the formation of globes 

 of vapour, which, in issuing from the mouth of the aperture, carried 

 up bladders of the liquid lava. This action continued often for 

 more than a quarter of an hour, and then suddenly a louder detona- 

 tion would be heard, which was followed by a violent escape of 

 steam from the aperture and the ejection of a thousand fragments 

 of glowing lava to a great height. Where the crater joins the steep 

 slope of the Sciarra, a third and much smaller opening was seen, 

 from which a little stream of lava, like a perennial fountain, was 

 constantly issuing; it flowed down the Sciarra towards the sea, 

 which, however, it did not reach, becoming solid before it arrived 

 at the bottom ; some portions, however, of the congealed mass were 

 continually becoming detached and rolling down into the water. 

 The position of this lava- stream on the Sciarra is represented in 

 Hoffmann's drawing of Stromboli. 



On the 25th of July, 1836, Abich visited the crater of Stromboli. 

 He saw in the midst of the crater a throat 60 or 70 feet in diameter, 

 in which glowing lava could be perceived moving up and down ; 

 and several smaller openings were also visible by the side of it. 

 Another mouth at the junction of the crater with the Sciarra dis- 

 charged showers of stones at intervals of 6 or 7 minutes ; the latter 

 had formed a miniature cone about 20 feet high on the depressed edge 



