Page:Great Neapolitan Earthquake of 1857.djvu/140

 was prostrate. This tower was, however, also aided by iron chain bars, built in at each story. The great viaduct carrying the military road at Campostrina is another example. Indeed, it was evident, that had the towns generally been substantially and well built, or, rather, the materials scientifically put together, very few buildings would have been actually shaken down, even in those localities where the shocks were most violent, and their directions the most destructive. Thus the frightful loss of life and limb, were as much to be attributed to the ignorance and imperfection displayed, in the domestic architecture of the people, as to the unhappy natural condition of their country, as respects earthquake.

In a wall of parallelopipedal blocks, properly overlapping and breaking joint, the aggregate tenacity, of a vertical serrated transverse line of joints, may be represented, as Professor Rankine has shown, by an equation of the form $\mathrm{T}=n\frac{n+1}{2}f,\delta$ x $bht$ the last letters being the dimensions of the wall at the serrated section: $$n$$, the number of courses; $$f$$, the co-efficient of friction, which may equally be taken as the co-efficient of adherence of the mortar, irrespective of its own coherence, and $$d$$, the specific gravity of the stone or brick. Unfortunately, we still need better experimental data as to the adhesion of mortar, in directions both parallel, and transverse, to the bed surfaces, to enable us to apply the numerical results to earthquake-applied strains producing vertical or inclined serrated fissures. The like