No building showed the different kinds of evidence on which Mallet relied as clearly as the cathedral church at Potenza, the plan of which is given in Fig. 5, and the vertical section along its axis in Fig. 12. This is a modern work, nearly 200 feet long, with its axis directed east and west. The walls are composed of fairly good rubble masonry and brick; and the arches in the nave and transepts, the semi-cylindrical roof and the central dome are made of brick. The fissures represented in both diagrams were drawn to scale by the cathedral architect before Mallet's arrival, and, as the work of an unbiassed observer, are of special value. Most of those in the roof, it will be seen, were transverse to the axial line of the church; but there were others parallel to this line, one in particular running right along the soffit of the nave and chancel. There were also numerous small fissures in the dome, due to local structural causes and therefore of varying direction, and a large portion of the dome slipped westward, leaving open fissures of seven to eight inches in width. The mean direction of the wave-path, as deduced from nine sets of fissures, none of which differs more than four degrees from the mean, is W. 2-1/2° S. and E. 2-1/2° N., which corresponds precisely with the direction of throw on the displaced portion of the dome. The great east and west fissures in the arch of the nave and chancel Mallet attributed to a second shock, of the existence of which there is ample evidence. [Illustration: FIG. 6.--Fallen gate-pillars near Saponara. (_Mallet._)] Next to fissures, Mallet made most use of overthrown objects, such as the two gate piers near Saponara, represented in Fig. 6. They were made of rubble ashlar masonry, three feet square and seven feet in height. Both were fractured clean off at the level of the ground, the mortar being poor, and fell in directions that were accurately parallel, indicating a wave-path towards S. 39-1/2°E. A few observations were also made on projected stones, fissures in nearly level ground, and the swinging of lamps and chandeliers; but their value was small, except as corroboration of the more important evidence afforded by fissures in the walls and roofs of buildings.