by that of the east and west Apennine from Naples and south of it, to Spinazzola on the east, in which the clustering of the focal points again is at Melfi, and about Vesuvius and Naples.
The locus line of foci then follows N.W. from about Melfi, through the line of the Great Majella of the central Apennine, by Campobasso and Sulmone; delivering its greater energies towards the Adriatic, at which side of the central ridge therefore the focal cavities must be situated. About the Lago Fucino there is almost a gap; a considerable space here, right across the peninsula, from the Pontine Marshes to Giulia Nuova and Atri, on the Adriatic, being almost free from shocks, originating within it. Northward of this, the locus line of foci divides, one following the eastern, the other the western, great and approximately parallel ridges, of the Apennine. The eastern line includes the band of never-ending shocks, centred along the line, passing through Aquilla, Montereale, Norcia, (of the latest of whose earthquakes, August 1859, Padre Secchi, of Rome, has given so interesting an account,) and Asisi. The western line, is that of the Alban Hills, Rome, Viterbo, and to Orvieto and the Lago Bolsena. Then there comes another breach of continuity, and a wide district about the Lago di Perugia, is almost exempt from shocks originating within it. Still northward of this, the Tuscan earthquake regions, follow generally the line of the western ridge of the Apennine; and the eastern line of foci, by Urbino, Rimini, and Ravenna, that of the mountains inland and more or less parallel with these, runs northward, and with several diminutions of intensity as to focal distribution, connects with the seismic system of the Rhetian Alps, and of Hungary.
