precede the final crash and rupture that produces the shock, or whether volcanic action going on in the unseen depths below may give rise to powerful disturbances of electric equilibrium, and hence to the development of light; just as from volcanic mountains in eruption lightnings continually flash, from the huge volumes of steam and floating ashes above the crater.
Atena, which in Pliny's time gave its name to the whole valley (campi Atenati), is a town of extreme antiquity, its name indicating its Greek foundation. It is situated upon the east side of the great valley, and stands upon the crest, of a spur of absolutely bare rock, jutting from the lateral range, and having a small transverse valley or gorge to the north of it. The slope or angle of emergence of the rock, to the north of the town, from beneath the deep alluvium is about 30° with the horizon at a (Fig. 187); the bedding ill-defined but apparently with a general east and west strike and steep dip.
Don Vincenzio Jachetti, an inhabitant, an intelligent man, who had been appointed a Deputy Sotto Intendente since the earthquake, accompanied me over the town, which has suffered terribly; its streets, especially upon the north and south sides, are choked with rubbish of fallen buildings to a depth of 10 or 15 feet above the former level, and encumbered with fractured and entangled beams and joists.
The Photog. No. 189 (Coll. Roy. Soc.) shows the east end of the cathedral church, and various adjoining buildings, looking nearly westward. The general evidence of the wave-path with steep emergenee from the north, is observable in the thrown and shattered north and south walls, and in the wedge-like mass, projected from the S. E. quoin of
