Page:Aspects of nature in different lands and different climates; with scientific elucidations (IA b29329668 0002).pdf/242

 his uncle's death, it may be clearly seen that the renewal of volcanic outbursts, or what might be called the revival of the slumbering volcano, began with an eruption of ashes. The same thing was observed at Jorullo when, in September 1759, the new volcano, breaking through beds of syenite and trachyte, rose suddenly in the plain. The country-people took flight on finding their huts strewed with ashes which had been emitted from the everywhere opening ground. In the ordinary periodical manifestations of volcanic activity, on the contrary, the shower of ashes marks the termination of each particular eruption. There is a passage in the letter of the younger Pliny which shews clearly that, at a very early stage of the eruption, the dry ashes which had fallen had reached a thickness of four or five feet, without accumulation from drift or other extraneous cause. He writes, in the course of his narrative, "the court which had to be crossed to reach the room in which Pliny was taking his noon-day repose was so filled with ashes and pumice, that, if he had longer delayed coming forth, he would have found the passage stopped." In an enclosed space like a court, the action of wind in drifting the ashes can scarcely have been very considerable.

I have interrupted my general comparative view of volcanos by a notice of particular observations made on Vesuvius, partly on account of the great interest excited by the recent eruption, and partly on account of those recollections of the catastrophes of Pompeii and Herculaneum, which are almost involuntarily recalled to our minds by the occurrence of any considerable shower of ashes. I have