Page:Great Neapolitan Earthquake of 1857.djvu/454

level and smooth, and the arrises perfect; and the upper and lower parts had been merely laid together, without any cementing material.

All the parts, like those of the column, &c. preceding, had remained untouched since their fall by the earthquake.

The centre of gravity of the upper part of each vase, (that projected off,) I found by trial was at 10 inches above the joint $e$, and the weight by trial, was 94 rotuli = 183 lbs. avoir. nearly.

The vase $\mathrm {A}$ had been thrown so, that its centre of gravity had been displaced 6.50 feet in the horizontal, and 3.60 feet in the vertical direction. We get the velocity of projection from the equation

$\mathrm {V} ^{2}={\frac {a^{2}g}{2\cos ^{2}e\left(b+a\tan e\right)}}$

in which $a=6.50$, $b=3.60$, $e=25^{\circ }30'$, as before.

Then

$\mathrm {V} ^{2}={\frac {42.25\times 32.2}{1.629\times \left(10.1\times 0.4769\right)}}={\frac {1360.50}{7.85}}$

$\mathrm {V} ^{2}=173\therefore V=13.152$ feet per second,

which only differs from the velocity given by the fallen column, by 0.566 foot, or a little more than 6 inches per second.

As respects horizontal direction, the vase A had been thrown in precisely the same path as the column preceding, viz., 15° W. of north towards the south; and its axis of symmetry was twisted as it lay, about 12° in a horizontal plane, from the vertical plane of projection, as seen in diagram, and it was obvious, from examination of the truf beneath, that it had not rolled after it struck the ground.