We have seen that, in the three earthquakes of 1828, 1881, and 1883, there is distinct evidence of a second meizoseismal area at Fontana, within which the shock was mainly subsultory. Dr. Johnston-Lavis, though recognising the possibility of the existence of two epicentres, prefers another explanation.[29] But the wide extension of the southern boundary of the area of destruction in 1883, and the limitation of several of the after-shocks to the south of the island, seem to me to favour the existence of a second focus beneath the crater of Epomeo, though, it may be, not entirely detached from the chief focus beneath Casamenella. Again, as Professor Mercalli remarks, all historic eruptions on the flanks of Epomeo were accompanied by very violent earthquakes; while, previously to 1302, only one disastrous earthquake, so far as known, occurred in the island without being attended by an eruption. It should be noticed also that the principal shocks during the recent revival of activity (_i.e._, since 1762) show a continual increase in intensity, whether this be measured by the damage to buildings, the loss of life, or the extent of the area of destruction (Fig. 14). It therefore seems legitimate to conclude that, in the recent Ischian earthquakes, we have merely so many unsuccessful attempts to force a new volcanic eruption. The passages once existing through Epomeo and its parasitic craters having become blocked, the highly heated magma beneath is compelled to find a new outlet. Its tension slowly increasing, the crust above is at last rent, or an incipient rent is enlarged, the fluid rock is injected almost instantaneously with great force into the open fissure, and its sudden arrest by the containing walls is the ultimate cause of an earthquake. With the expansion of the magma, its tension is at once correspondingly reduced, and some time must elapse before it can again reach the critical point at which a further rupture, resulting in a second shock, takes place.[30] Thus, with each great Ischian earthquake, we are, I believe, advancing a step nearer the time, which may be close at hand or may be very remote, when the fracture will at last reach the surface, and above the site of Casamenella a new parasitic cone will rise, from which, as from Cremate in 1302, a stream of lava may flow down towards the sea. REFERENCES. 1. BALDACCI, L.--"Alcune osservazioni sul terremoto avvenuto all' Isola d'Ischia il 28 luglio 1883." _Ital. Com. Geol. Boll._, vol. xiv., 1883, pp. 157-166. 2. DAUBRÉE, A.--"Rapport sur le tremblement de terre ressenti à Ischia le 28 juillet, 1883; causes probables des tremblements de terre." Paris, _Acad. Sci._, _Compt. Rend._, vol. xcvii., 1883, pp. 768-778. 3. DU BOIS, F.--"The Earthquakes of Ischia." _Japan Seism. Soc. Trans._, vol. vii., pt i., 1883-84, pp. 16-42. 4. ---- "Farther Notes on the Earthquakes of Ischia." _Ibid._, vol. viii., 1885, pp. 95-99.