Notice of Active and Extinct Volcanos. 27 1 



sufficiently terrific to give me an idea of what takes place during 

 an eruption of Etna or Vesuvius, but as the wind did not blow 

 the stones in our direction, we should have incurred no conside- 

 rable risk in approaching it nearer. On expressing however this 

 wish to my guides, I was reminded, by their refusing to accom- 

 pany me, of the remark which Spallanzani makes in respect to 

 the superstitious horror entertained in his time by the Liparotes 

 of the crater of Volcano, which obliged him to procure a Cala- 

 brian for his attendant ; and finding that no one would venture to 

 accompany me nearer, I thought it prudent to abandon the at- 

 tempt." 



Pumice so well known in the arts, abounds in the Lipari isl- 

 ands, whence most of that used in Europe and America is ob- 

 tained, and obsidian is considerably abundant, although it is 

 difficult to say what circumstances determine volcanos to pro- 

 duce these forms of ignigenous materials rather than others. 

 Dr. Daubeny thinks that 



" For the formation of pumice it seems requisite that a con- 

 siderable disengagement of vapor should have taken place, 

 during the time at which the body acted upon was in a plas- 

 tic, though not in an altogether fluid condition." 



The vitreous lavas of Lipari, (obsidian,) are not always 

 loosely ejected, suddenly cooled masses, but they constitute 

 " extensive beds, which ought, it would seem to have been 

 subjected to the same laws of congelation as the lavas of oth- 

 er volcanos." 



The only indications of active volcanic agency now exist- 

 ing in the island of Lipari, are the hot springs, about four 

 miles west of the town, but ancient authors speak of volcanic 

 eruptions and earthquakes as so common in these islands that 

 probably the inhabitants had acquired that degree of familiar- 

 ity with them which is ascribed by Humboldt to the inhabit- 

 ants of Peru : — 



" On the coast of Peru, earthquakes are so frequent, that we 

 become as much accustomed to the undulations of the ground, 

 as the sailor is to the tossings of the ship, caused by the motion 

 of the waves. 



" From our infancy, the idea of certain contrasts fixes itself in 

 our minds ; water appears to us an element that moves ; earth, a 

 motionless and inert mass. These ideas are the eifect of daily 

 experience ; they are connected with every thing that is trans- 

 mitted to us by the senses. When a shock is felt, when the earth 

 is shaken on its old foundations, which we had deemed so stable. 



