J. W.Judd—On Volcanos. 207 



outside. On the night of the 31st of May, 1855, as witnessed from 

 the sea, they were 15-3-15-17-11-15-16-3-4-8-16-4-5-3 minutes. 

 On the night of the 14th October in the same year, as seen from 

 the edge of the crater, they were 15-4-3-12-11-14-13-2-3-6-6-3 

 minutes. Of five successive intervals, noted in daylight on the 13th 

 June, 1855, the longest was 21 minutes and the shortest 4 minutes. 



In the latter part of 1864, Mr. Eobert Mallet and Colonel Yule 

 ascended to the crater of Stromboli. They were unable to see the 

 floor on account of vapours which issued from the bottom and 

 sides. Although the actual vents were not visible, Mr. Mallet was 

 led to infer that the explosions took place from different points of 

 its bottom, and he found the intervals between them to vary between 

 30 or even 40 minutes and 2 minutes. Each outburst "was pre- 

 ceded by several distinct low detonations, with intervals between 

 each of from 4 to 5 seconds to as much as 80 seconds : these, though 

 of a far deeper tone, greatly resembled the cracking noises that are 

 heard when steam is blown into the water of a locomotive tender 

 for the purpose of heating it." The outbursts themselves are de- 

 scribed as not being quite instantaneous in character, but as begin- 

 ning with a hollow growl and clattering sound increasing to a roar, 

 which endures for a few seconds to a minute or two, and then 

 rapidly declines. Both the preliminary detonations and the shock 

 of the outburst are stated to have sensibly shaken the ground on 

 which the observers stood. 



During the eruption of Etna in the beginning of 1865, Stromboli 

 is said by the inhabitants of the island to have been in a state of 

 extraordinary activity. The explosions were more violent than 

 usual, liquid lava was emitted from the crater, and showers of ashes 

 during several days covered the entire island. At the time when 

 M. F. Fouque visited the volcano, in the summer of the same year, 

 it had, however, resumed its ordinary condition of subdued eruption. 



In 1867, M. Jannsen made some spectroscopic examinations of the 

 ignited gases within the crater of Stromboli; but his observations 

 on this volcano appear to have been attended with considerable dif- 

 ficulty. In 1870, Dr. Julius Schmidt made some observations on 

 the condition of the volcano. 



On the 18th of April, 1874, after having on preceding days ex- 

 amined the lower portions of the mountain, I climbed up to the 

 summit before sunrise, and descending thence a few hundred feet, 

 spent five hours in examining the phenomena from near the edge of 

 the crater. On this occasion, as in my other journeys in the Lipari 

 Islands and Sicily, I was accompanied by Signor Pasquale Franco, 

 of the University of Naples. During the asGent, I had a lateral view 

 of the crater during one of the explosions, as seen from the side 

 of the Schiarra ; of this explosion I made the accompanying sketch 

 (Fig. 12). On the north side of the crater a fissure is seen thickly 

 encrusted with yellow salts, which is called the " Filo-della-solfre." 

 The explosions appeared to me not to take place from the centre of 

 the crater, but from near its north-western side. 



Like all who have, during at least ten years past, examined the 



