772 
PROCEEDINGS OF SECTION H. 
ordinarily built in Ischia gives them enormous inertia, so that it is 
some time before the earth’s movements can be communicated to them; 
and as a result, when the foundation is carried forward by the earth, 
the upper part lags behind. When the earth returns the upper part 
has commenced to move forward, but the foundation is going backward, 
so that the walls are fissured and broken by the strain between their 
free and their fixed portions or foundations, often crumbling to pieces, 
since their elasticity and the cohesion of their constituent parts are 
almost nil compared with their weight. We therefore see,” he says, 
u that for buildings to withstand principally undulatory movements 
two methods may be adopted — the first to make them stronger, so 
that they may be able to resist such movements, or they may be 
isolated in some way from the ground.” 
If resort be had to tiebars they should form a complete frame- 
work to all the walls and floors which from their quadrangular form 
require breaking up into triangles by diagonal bars from one corner 
to another. The objections to mixing iron bars and masonry are 
twofold : first, the diagonal bars from the lower corner of a wall on 
one side to the upper one opposite would require a special arrange- 
ment of doors and windows so as not to interfere with them, a 
difficulty which all architects will but too fully realise. Secondly, the 
continual strain produced by change ot‘ temperature in causing 
contraction and expansion of the iron bars running in different 
directions, although slow, would be a sure agent in the gradual disin- 
tegration of the masonry. There is no doubt possible that a moderately 
secure house might be made by combining masonry with a network 
of tiebars or girders in the walls and floors, so that they could resist 
both Bubsultory aud undulatory shocks. Auotber principle that could 
be adopted with greater success is to employ materials with the 
minimum of inertia aud the maximum of adhesion and elasticity. 
Such material is to be had in wood and iron. 
He concludes that for Ischia, the locality under consideration, it 
will be found convenient to construct houses of iron and wood, the 
latter being used for lining. Tor the floor a solid framework of iron 
orwood,with a judicious introduction of hollow tiles and good concrete, 
would be justifiable. The floors, and in some rooms even the walls, 
might be covered by thin Trench tile's ; in fact, if the houses are 
designed in a proper manner they may be made more hygienic, more 
commodious, and pleasanter than those of masonry. 
We have seen that the main cause of destruction in the houses is 
due to the earth’s movements being communicated to the upper parts 
too late, and after the foundations have commenced to move. This 
weakness might be overcome by using strong tiebars attached to the 
iron framework. 
Having now, as far as I am able, explained the different methods 
or so-called earthquake-proof construction in regions where earth- 
quakes are prevalent, permit me to add a few words before I close 
this paper. 
In 1850, Eobert Mallet, with his son, completed a catalogue of 
earthquakes for the British Association. Beginning at the earliest 
accepted chronological time, or 2,000 years before the Christian era, 
they continued on until 1850, thus comprising a period of 3,850 years. 
