Chap. 47.] Olfcrvatims on the Great Crater. 355 

 help of torches it was fcarcely poffible to keep in the 

 high road. On the i6th of July, fignor Guifeppe 

 Sacco went up to the crater, and, according to his 

 account, which has been printed at Naples, the crater 

 is of an irregular oval form, and as he fuppofes (not 

 having been able to meafure it) of about a mile and 

 a half in circumference ; the infide, as ufual, in the 

 fhape of" an inverted cone, the inner walls of which 

 on the eaftern fide are perpendicular} but on the 

 weftern fide of the crater, which is much lower, the 

 defcent was practicable, and Sacco with fome of his 

 companions actually went down one hundred and 

 feventy-fix palms, from which fpot, having lowered 

 a cord with a (tone tied to it, they found the whole 

 depth of the crater to be about five hundred palms. 

 But fuch obfervations on the crater ofVefuvius are 

 of little confequence, as both its form and apparent 

 depth are fubjeft to great alterations from day to day. 



The 22d of July, one of the new craters, which is 

 the neareft to the town of Torre del Greco, threw up 

 both fire and fmoke, which circumftance, added to 

 that of the lava's retaining its heat much longer than 

 ufual, feemed to indicate that there was ftill fome 

 fermentation under that part of the volcano. The 

 lava in cooling often cracks, and caufes a loud explo- 

 fion, juft as the ice does in the glaciers in Swificrland ; 

 fuch reports were frequently heard at this time at the 

 Torre del Greco ; and a vapour was often feen to ifiue 

 from the body of the lava, and taking fire in air, fall 

 like thofe meteors vulgarly called falling flars. 



-The darkncfs occafioned by the fall of the afhes in 

 the Campagna Felice extended itfelf, and varied, ac- 

 cording to the prevailing winds. On the I9th of 

 June it was fo dark at Caferta, which is fifteen miles 

 from Naples^ as to oblige the inhabitants to light can- 

 A a 2 dies 



