_Mallet's Determination of the Epicentre._--Within the third isoseismal line Mallet made altogether 177 measurements of the direction of the wave-path at 78 places. These are plotted on his great map of the earthquake; but, owing to the small scale of Fig. 9, it is only possible to represent, by means of short lines, the mean or most trustworthy direction at each place.[14] Producing these directions backwards, he found that those at sixteen places passed within five hundred yards of a point which is practically coincident with the village of Caggiano; those at sixteen other places passed within one geographical mile (1.153 statute miles) of this point; the directions at sixteen more places within two and a half geographical miles; while those at twelve places passed through points not more than five geographical miles from Caggiano. As the direction of the shock at places near the epicentre must have been influenced by the mere size of the focus, this approximate coincidence is certainly remarkable, and there can be little doubt, I think, that the epicentre, or, at any rate, _an_ epicentre must have been situated not far from the position assigned to it by Mallet's laborious observations. _Existence of Two Epicentres._--It is difficult, however, to realise that the impulse at the focus corresponding to Mallet's epicentre was the origin of all the destruction of life and property that occurred. The position of the epicentre close to the north-west boundary of the meizoseismal area, the extraordinary extension of that area towards the south-east, and especially the great loss of life at Montemurro and the adjoining towns, can hardly be accounted for in this manner. Mallet himself recognised that these facts required explanation, and he suggested that the situation and character of the towns were in part responsible for their ruin, and the physical structure of the country for the course of the isoseismal lines. But the comparative escape of places much nearer Caggiano, and the wide extent of the meizoseismal area, embracing many towns and villages of varied character and site and many different surface-features, point unmistakably to a different explanation. [Illustration: FIG. 10.--Distribution of death-rate within meizoseismal area of Neapolitan earthquake.]