58 Sir william Hamilton’s Account of 
The black cloud in-creafing greatly once bent towards 
Naples, and feemed to threaten this fair city with fpeedy 
deftrudtion ; for it was charged with electrical matter, 
which kept conftantly darting about it in ltrong and 
bright zig zags, juft like thofe defcribed by pliny the 
younger in his letter to tacitus, and which accompa- 
nied the great eruption of Vefuvius that proved fatal to 
his uncle- This volcanic lightning, however, as I par- 
ticularly remarked, very rarely quitted the cloud, but 
ufually returned to the great column of fire towards the 
crater of the volcano from whence it originally came n> . 
Once or twice, indeed, I faw this lightning (or ferilii as it 
is called here) fall on the top of Somraa, and fet fire to 
fome dry grafs and bullies (m) . 
Fortunately 
( k ) <c Ab altero latere, nubes atra, et horrenda, ignei fpiritus tortis vi 
il bratifque difcurfibus rupta, in longas fiammarum figuras dehifcebat; fulgoribus 
(e illae, et fimiles et majores.” plin. Epifl* 
(l) sorrentino mentions the like obfervation, which he made during an 
eruption of Vefuvius in 1707, when the fame kind of black cloud bent over 
Naples; thefe are his words. u Alle ore 19. tutti i cittadini nelle ofcure tenebre 
u li trovarono in mezzo delle Saett€, delle quali, alcune vedeanfi ufcirdalla for- 
cc nace del Vefuvio, e fcorrere fino al capo di Paulilipo, d^onde non paiTando 
* 6 piu inanzi fuor la nuvola delle ceneri, o divertirfi altronde, indietro per 
(( Fiftefla linea tornarono a fcopiar fu lafornace, onde ufcirono : qual moto re- 
Si trogrado mai hopotuto intendere.” 
(m) Some time after the eruption had ceafed, the air continued greatly im- 
pregnated with elettrical matter. The Duke of Cotrofiano, a Neapolitan 
nobleman (who, from his fuperior knowledge in experimental philofophy and 
5 mechanics, 
