[40] The noxious vapours which Lucan mentions to have prevailed at Nisida, favour my opinion as to its origin: "--Tali spiramine Nesis "Emittit stygium nebulosis aera saxis." Lucan. lib. vi. [41] Giulio Cesare Capaccio, in his account of this island, says, that there are eleven springs of cold water, and thirty-five of hot and mineral waters. [42] By having remarked, that all the implements of stone brought by Mess. Banks and Solander from the new-discovered islands in the South-Seas, are evidently of such a nature as are only produced by Volcanos; and as these gentlemen have assured me, that no other kind of stone is to be met with in the islands; I am induced to think, that these islands (at so great a distance from any continent) may have likewise been pushed up from the bottom of the sea by like explosions. [43] Any one, the least conversant in Volcanos, must be struck with the numberless evident marks of them the whole road from the lake of Albano to Radicofani, between Naples and Florence; and yet, though this soil bears such fresh and undoubted marks of its origin, no history reaches the date of any one eruption in these parts. [44] May not the air in countries replete with sulphur be more impregnated with electrical matter than the air of other soils? and may not the sort of lightning, which is mentioned by several ancient authors to have fallen in a serene day, and was considered as an omen, have proceeded from such a cause? Horace says, Ode xxxiv. "--Namque Diespeter "Igni corusco nubila dividens "Plerumque per purum tonantes "Egit equos volucremque currum." "Non alias coelo ceciderunt plura sereno "Fulgura----" Virgil. Georgic. i. "Aut cum terribili perculsus fulmine civis "Luce serenanti vitalia lumina liquit." Cic. i. de Divin. n. 18. "--Sabinos petit aliquanto tristior, quod sacrificanti hostia aufugerat: quodque tempestate serena tonuerat." Sueton. _Tit._ cap. 10. [45] This letter was not received by Dr. Maty in its present form: and is rather the substance of an explanatory catalogue, which was sent to that gentleman with sundry specimens of the different materials that compose the soil described in the preceding letter; which catalogue remains, with the specimens, in the Museum of the Royal Society, for the inspection, and, I flatter myself, the satisfaction, of the curious in natural history. [46] See p. 103 of this collection. [47] See Letter I. p. 18.