CHAPTER I.
THE REGION OF OBSERVATION—ITS SEISMIC HISTORY—OBSERVATIONS AT AND AROUND NAPLES.
The seismic region to which this Report refers reaches in its most extended sense from Rome to Otranto, in a west and east direction, and from Gargano to Reggio in that north and south; since within the whole of this surface—in fact, over the whole of the peninsula south of the parallel of 42°—was the earthquake of the 16th December, 1857, more or less perceptible. In the more restricted sense, however, in which the seismic area is limited by the effects of the shocks having been forced upon the attention of the inhabitants, and left tangible traces of their advent, and thus determined the scope of the writer's observations and inquiries, it may be said loosely, to be bounded by a line stretching eastward from Sermoneta, at the head of the Pontine Marshes, to Foggia in Capitanata, and thence to the Adriatic; and comprehending all south of that, excepting the peninsula of Otranto, east of a line between Monopoli and Taranto and the peninsula of Calabria Ultra, south of a line from Cape Suvero to Cape Colonna, thus embracing the surface between lat. 39° and 41° 30' and from long. E. 10° 30' to long. E. 15° or more than 200 English miles by above 160.
