The Philosophical magazine; a journal of theoretical, experimental and applied physics . Archipelago, Madeira, Teneriffe,the Azores, Bourbon, St. Helena, Barren Island, the LeewardIsles, &c.), will see numerous unquestionable examples of thislaw by which crater is formed within crater, and new cones uponthe ruins of old ones. History of Vesuvius.—At the risk of repetition, I must be per-mitted to illustrate this law by the trite, but instructive, exampleof Vesuvius,—which only comes so often before us because fromits proximity to Naples it has been open to more constant andaccuiate observation
The Philosophical magazine; a journal of theoretical, experimental and applied physics . Archipelago, Madeira, Teneriffe,the Azores, Bourbon, St. Helena, Barren Island, the LeewardIsles, &c.), will see numerous unquestionable examples of thislaw by which crater is formed within crater, and new cones uponthe ruins of old ones. History of Vesuvius.—At the risk of repetition, I must be per-mitted to illustrate this law by the trite, but instructive, exampleof Vesuvius,—which only comes so often before us because fromits proximity to Naples it has been open to more constant andaccuiate observations than any other known volcanic , in brief, is the history of this volcano during the last cen-tury ? Precisely one hundred years ago, in the year 1756,Vesuvius possessed no less than three cones and craters, onewithin the other, like a nest of boxes, besides the great encir-cling crater and cone of Somma (fig. 1). Sir W. Hamiltongives us a drawing of its appearance in this state. Fig. 1.—Outline-sketch of Vesuvius as it existed in 1756.(After Sir W. Hamilton.). By the beginning of the year 1767, the continuance of mode-rate eruptions had obliterated the inmost cone and increased theintermediate one, until it very nearly filled the principal crater(fig. 2, A, b). An eruption in October of that year, 1767, com-pleted the process, and re-formed the single cone into one con-tinuous slope all round from the apex downwards (fig. 2, c).The dotted lines in fig. 2 (after Hamilton) represent the shapeof the outer and inner cones before this eruption, and the spacebetween them and the firm outline repiesents the amount bywhich the cone was in the intervening ten years augmented inbulk and height by the ejectameata of that eruption. An in-terval of comparative tranquillity followed, until, in 1794, theparoxysmal eruption occurred, described by Breislak, which com-pletely gutted this cone, then solid, lowered its height, and left 140 Mr. G. P. Scrope on the Formation of
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