138 Accoiint of a Dcfce?it 



traits of the eight Frenchmen who had defccnded. Each 

 then formed a imall colleftion of the difierent volcanic mat- 

 ters which appeared to be new or cunous, and endeavoured 

 to make a few oblervations. 



Had we been allowed to depend on fucccfs, had we not 

 been retarded in our preparations by our timid guides, and 

 if feme of us, having only ju(l arrived at Naples, had not 

 been Itraitened in point of time, our defcent would certainly 

 have been much more ufeful, and the refults more fatisfac- 

 tory. However, though ill furnifhed with means, the fol- 

 lowing are the obfervations we were enabled to make : 



Keaumur's thermometer, the only inftrument we polTefled, 

 flood at 12 degrees, on the fummit of Vefuvius: the air was 

 Gold, and fomtwhat nioifl : in tiie crater the quickiilver rofe 

 to 16 degrees, and we experienced the mildelt temperature. 



The furface of this place, which, when feen by the naked 

 eye, looking down from above, appeared entirely fmooth, 

 exhibited, when we were at the bottom, nothing but a vaft 

 extent of afperities. We were conilanlly obliged to pafs over 

 lava exceedingly poioas, in general pretty hard, but which 

 in fome places, and particularly thofe where we entered, was 

 ftill fofl, and yielded under our feet. The fpettacle which 

 ftruck us moft was the numerous fpiracles, which either at 

 the bottom of the crater or the interior fides of the mountain 

 fuffer the vapours to efcape. When we arrived at the crater, 

 we were deiirous to afcertain whether thele vapours were of a 

 noxious quality : we walked through them, and infpired tliem 

 feveral times, but felt no inconvenience from them. The 

 thermometer placed in one of theie fj/iracles indicated 54 de-^ 

 grees, in another it rofe only to 23. In all thele experiments 

 our inftrument was covered with a humid matter, which was 

 foon difl]j)ated in the open air without leaving any traces. 



In traverfing the iurface of the crater, we perceived a focus 

 half covered by a large mafs of pumice Itone, and which, 

 from its whole circumference, emitted a ftrong heat. The 

 t-hcrmomctcr placed at firft at the entrance of it, and then 

 immerled to as great a depth as the nature of the ground and 

 the heat would admit, never rofe higher than 22 degrees. 

 This fincularitv fiirpriftd us, but wc were not able to ex- 

 plaui It. 



'Hie volcanic produclions which we ohferved in the whole 

 crater were lava, exceedingly porous, and which the fire in 

 certain places had reduced to fcoriae. It was of a dark brown 

 colour, and fomeiimes reddifli, but it is rare to find any 

 white. The fubftanccs neareft the fpiracles are all covered 

 or impregnated 'vith fulpluir. This mineral is found very 



often 



