298 Dr. Donati on the 



lower part of the funnel, resounded in a manner which showed 

 that the ground was hollow ; the lava forming only a super- 

 ficial volcanic crust. Signer Monticelli, who, together with 

 Professors Corelli, Petagno and Costa *, was a spectator of 

 my adventurous exploit, gave an account of it to the Royal 

 Academy of Sciences. I was able to measure, by approxima- 

 tion, the depth of the interior of the crater, which was the same 

 as I have already indicated (one hundred and sixty-six toises). 

 A large quantity of materials rolling from the inside of the crater 

 had filled the funnel at the bottom the volcanic aperture to the 

 north Was exhausted, and that to the east had so far diminished 

 in activity, that scarcely any vapour proceeded from it, But 

 towards the end of 1827, others broke out on the southern 

 side of the interior of the crater, which produced much per- 

 oxide of iron, in brilliant laminae of a fine deep red colour ; 

 muriate of copper resembling lichen, and large stalactites of 

 muriate of soda. The sides of the crater were much split 

 near this part ; and after a few months these, also, were pre- 

 cipitated into the bottom of the abyss. 



On the 14th of March, 1828, suddenly, and without any 

 previous notice, either by the disappearance of water or 

 trembling of the earth, at about two o'clock in the after- 

 noon, the above mentioned aperture near the bottom of 

 the crater on the eastern side, although apparently exhausted, 

 gave a tremendous shock, which not only shook the cone 

 of the volcano, but was felt as far as the Hermitage the 

 forerunner of a new eruption | ! The air now resounded 

 with thunder and hollow bellowings ; and from time to time 

 shocks succeeded each other with increasing violence. All 

 kinds of loose and detached substances which formed the 

 covering of the aperture, were projected into the air; and 



* Signer Costa found at the same time, near the mouth which produced the 

 bisulphuret of copper, some insects of the family Cloteropti, which existed in a 

 temperature of 60 Reaumur, and in an atmosphere loaded with scorching dust. 



-j- On the 14th of March, occupied in mineralogical researches, I traversed the 

 Fossa Grande, after having visited the Atrio del Cavallo, where a stratum of 

 vitreous trachyte occurs, in which small laminae of brown mica are disseminated. 

 This rock is exactly similar to that called by the Italians Occhi di Pernici ; and 

 to another found in the Isle of Paneira. Scarcely had I felt the first shock, 

 when, expecting an eruption, I mounted the very summit of the cone ; and was a 

 spectator of the first changes which took place. 



