Volcanos. 1 1 ! 



number already known is supposed very much within that which 

 really exists, for many reasons, but particularly because the 

 intervals of rest between eruptions are often of such long du- 

 ration that the former activity of the vent is unrecorded, and 

 again because it is probable that numerous vents exist under 

 the sea, whose activity however frequent, cannot be made 

 known to us till the peak of the volcano rises to within a short 

 distance of the surface. Volcanic phenomena are classed into sub- 

 aerial, or those which take place in the open air, and subaqueous. 

 Of the former class, which is more open to study than the lat- 

 ter, some take place from new, others from habitual vents. The 

 last are most common, and most accessible to observation. The 

 condition of all habitual volcanos, or sources of erupted mat- 

 ter, appears to belong to one or other of the three following 

 phases : 



" 1. In which the eruption is permanent (as in Stromboli, &c.) 



" 2. In which eruptions are frequent, prolonged, and of 

 moderate violence, and the intervals of repose short. 



" 3. In which intense eruptive paroxysms, of brief duration, 

 alternate with lengthened intervals of quiescence. 



" These phases are separately considered, and examples giv- 

 en of the phenomena of each, as well as a particular descrip- 

 tion of all the remarkable circumstances which accompany 

 and characterize a volcanic paroxysmal eruption, and which 

 appear to the author to present so great an uniformity in all pla- 

 ces, and at all times, as to warrant the conclusion that the main 

 phenomena are invariably the same ; ' no farther discrepancies 

 existing, than what are fairly referable to the modifications 

 produced by local accidents, or by differences in the intensity of 

 volcanic force developed, and in the mineral quality of the 

 erupted substances.' " 



Stromboli appears to have been in ceaseless activity for at 

 least twenty centuries, throwing out, not flames nor lava, but 

 scoriae. It is most violent before and during stormy weath- 

 er, especially in winter, when lava is said to burst occasional- 

 ly from its side into the sea, heating it to such a degree as to 

 boil the fish, which are cast on shore ready cooked. 



This volcano is viewed by the fishermen as a weather glass, 

 by which they auger the approach of tempests. 



The volcano in the Island of Nicaragua, called, by the sai- 

 lors, the Devil's Mouth, is said to be constantly active, and this 

 appears to be nearly the case also, with that of Kirauea in the 

 Island of Owyhee, (Hawaii,) but these instances are very rare. 



Many volcanos are in a state of moderate activity, with 



