Page:Great Neapolitan Earthquake of 1857.djvu/448

358 It is, therefore, obvious that the velocity of the shock was greatly below that that would have been necessary to fracture the column by its own inertia of motion, even if the cohesion which I have assumed for the limestone of which it was formed be much above the truth, as is probably the case. The calculation, however, removes the wonder with which the unaided senses regard so slender a stalk of stone found whole and uninjured, in the midst of bowing roofs and massive walls rent or overthrown.

In what had once been the garden of the palazzo stood a portion of a shaft of an old column—one of six—that had once formed some sort of garden edifice. It had been broken off and overthrown, and afforded a precious admeasurement both for direction of wave-path and velocity of shock.

The columns had all been originally formed of an artificial "beton" or concrete, of broken limestone and brick, and lime mortar, rudely formed enough, without any base moulding but a fillet, and were 17 inches diameter. They stood upon the top course of a continuous base of limestone, running round a large circular raised platform of earth. They had all been broken down and the shafts had disappeared to within a few inches of their bases years since, except this one portion of a shaft, which stood before the earthquake 4 feet 8 inches above its base. For 6 inches in height the shaft was a united block, and fast to the stone base; at this height an old fracture had existed, and a portion of shaft, 2 feet 10 inches in length, had stood upon the lower block, having been replaced upon it, and a little fine mortar interposed in the old fracture. In toppling over, at the north side of the column, the arris was broken out, and the diameter in N. and S. direction reduced to $15 1⁄2$ inches, as shown in Figs. 5 and 6, Diagram No. 221. Upon the