Page:Great Neapolitan Earthquake of 1857.djvu/263

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FIODO'S CLOCK.
213

upon statements of physical facts, so exaggerated and often inconsistent, as those in common circulation, though unaccompanied by intentional deception.

Signor Fiodo, Vico Baglievo, Strada Toledo, chronometer-maker to the Neapolitan Marine (who executed the needful repair and new rating to one of my English chronometers), I found a man of great intelligence, discretion in observation, and accuracy of thought, and from him I derived some of the most useful facts obtained at Naples.

In his "atelier" he has a regulator clock, with a heavy gridiron pendulum vibrating seconds, and, as I found, oscillating in an azimuth 20° E. of N. by compass. Resting upon the bottom of the clock-case, which is of polished chestnut, he had long placed a small steel anvil or parallelopiped of the exact dimensions shown and figured in Fig. 115, five sides of which are smooth, but black as when forged, and the sixth polished. This stood on edge, the polished side being next the pendulum (and behind it as one faced the clock), and the plane of this side, parallel with that of the oscillation—the polished surface being by measurement exactly 0.276 inch horizontally from the adjacent side of the screw at the bottom of the pendulum bob. The chord of oscillation of the pendulum measured at the screw was = 1.87 inch, and less than the parallel dimension of the steel block. A small amount of transverse movement, therefore, would be sufficient at any time to stop the clock by bringing the screw of the pendulum into contact with the face of the steel block.

On the morning of the 17th December, 1857, Signor Fiodo found this clock stopped, and the screw of the pendulum in contact with the south end of the steel block,