VOL. LVII.] PHILOSOPHICAL TRANSACTIONS. 4J7 



standing all their skill ar^d care, received the whole or part of the shock. To 

 remove this inconvenience entirely, the discharging frame is contrived, which, at 

 the same time that it prevents the wasting of the electrical fire, leaves no possi- 

 bility of the operator's ever receiving any shock. 



XX. Two Letters from the Hon. fVilliam Hamilton,* Envoy Extraordinary at 



Naples, containing an Account oj the last Eruption of Mount Fesuvius. Dated 



Naples, June 10, 1766, and Feb. 3, I767. 



Sir W. H. generally observed the smoke from the mouth of the Volcano was 

 much more considerable in bad weather than when it was fair ; and he often 

 heard (even at Naples, 6 miles from Vesuvius) in bad weather, the report of the 

 interior explosions of the mountain. When at the top of Mount Vesuvius in 

 fair weather, he sometimes found so little smoke that he could see far down the 

 mouth of the volcano, the sides of which were incrusted with salts and minerals 

 of various colours, white, green, deep and pale yellow. The smoke that issued 

 from the mouth of the volcano in bad weather was white, very moist, and not 

 near so offensive as the sulphureous steams from various cracks on the sides of 

 the mountain. Towards the month of September last, the smoke was more con- 

 siderable, continued even in fair weather ; and in October he perceived sometimes 

 a puff of black smoke shoot up a considerable height in the midst of the white, 

 which symptom of an approaching eruption became daily more frequent ; and 

 soon after, these puffs of smoke appeared in the night tinged like clouds with the 

 setting sun. 



About the beginning of November, he went up the mountain ; it was then 

 covered with snow, and he perceived a little hillock of sulphur had been thrown 

 up since his last visit there, within about 40 yards of the mouth of the volcano , 

 it was near 6 feet high, and a light blue flame constantly issued from its top. 

 While examining this phenomenon, he heard a violent report, and saw a column 



• Sir W. Hamiltoii was born in Scotland, of the noble family of that natne, in 1730 j and he 

 died at London the 6"th of April, 1803, in the 7-1 th year of his age. His education was liberal, and 

 he possessed an enlightened mind. And having been appointed ambassador to the court of Naples 

 in 1764, he there distinguished himself by his exei-tions in promoting the fine arts, in cc^lecting 

 antiquities, and advancing the interests of science, till his recal in 1800. He was indefatigable in 

 examining the volcanic mountains of Vesuvius and Etna, his valuable observations on which have 

 enriched many of the volumes of the Pbilos Trans, from which they have also been collected, and 

 republished with notes, in 1772, 8vo. And he greatly enriched the British Museum by his presents 

 of antiquities and other curiosities. His Campi Phlegroei, 2 vols, folio, is considered as a most in- 

 teresting and splendid performance. He was the chief promoter of the publication of that elegant and 

 magnificent work, Antiquiies Etrusques, Grecques, et Rumaines, tirees du Cabinet de M. Hamil- 

 ton, iheeditor of which was D'Hancarville. See other particulars of Sir W. H. in the Literary 

 Journal. 



VOL. XII. 3 H 



