608 PHILOSOPHICAL TRANSACTIONS. [aNNO 1755. 



of the fabric. The figure was a conoid, or an acuminated oval; its longer dia- 

 meter 20 inches, the shorter near the base 12. It was perforated on 2 opposite 

 sides, for the wasps to enter and go out at. The shell was composed of paper; the 

 sheets of which at its upper end were larger and more distinct. They were of an 

 ash-colour, of different shades, and streaked or marbled, and, being lightly laid 

 on each other, formed a wall of from 1-J^ to 4 inches thickness in the several parts 

 of it. The lax hollow manner, in which they were joined to each other, ren- 

 dered them a more effectual security from rain; as they attracted water in com- 

 mon with all other substances, made of the same materials; and would have been 

 more easily soaked through, if they had been closer compressed together. For 

 the same reason the apex of the cone was of the greatest thickness, and the base 

 of a stiffer and more cellulose texture. This substance appeared to be a true 

 paper; but, by the exact economy of nature, wrought to that degree of perfec- 

 tion only, which was necessary to serve the single purpose it was intended for. 

 Being examined by the microscope, it appeared to be of a coarser grain, a shorter 

 staple, and of a much looser texture; and was a rare, though not a singular in- 

 stance, of a natural production falling far short of the artificial one of the same 

 kind. The inside structure of these nests, is well described by M. de Reaumur. 



XXXIII. Abstract of a Letter from the Magistrates of the City of Mascali, 

 in Sicily, concerning a late Eruption of Mount Etna. From the Italian, p. 209. 



On Sunday, March 9, 1755, about noon, mount Etna began to emit a great 

 quantity of flame and smoke, with a most horrible noise. At 4 o'clock the air 

 became totally dark, and covered with black clouds ; and at 6 a shower of stones, 

 each of which weighed about 3 oz. began to fall, not only all over the city of 

 Mascali, and its territory, but all over the neighbourhood. This shower con- 

 tinued till a quarter after 7, that by the darkness of the air, the fall of stones, 

 and the horrible eructations of the mountain, the day of judgment seemed to 

 some to be at hand. After the stones had ceased falling, there succeeded a 

 shower of black sand, which continued all the remainder of the night. The 

 next morning, at 8 o'clock there sprung from the bottom of the mountain, as it 

 were, a river of hot water, which in the space of half a quarter of an hour, not 

 only overflowed to a considerable distance the rugged land, near the foot of the 

 hill, but, on the waters suddenly going off, levelled all the roughness and ine- 

 qualities of the surface, and made the whole a large plain of sand. The stones 

 and sand, which remain where-ever the inundation of the water reached, differ 

 in nothing from the stones and the sand of the sea, and have even the same 

 saltness. After the water had ceased flowing, there sprung from the same open- 

 ing 9. small stream of fire, which lasted for 24 hours. On Tuesday, about a 

 mile below this opening, there arose another stream of fire, in breadth about 



