EARTHQUAKES — INFLUENCE IN BUILDING- CONSTRUCTION. 771 
safely bear 20,000 lb. per square inch, and that the walls, if of good 
brick masonry, would stand safely 30,000 lb. per square foot of this 
kind of strain. 
Previous to 1868 it had been a general custom to make use of 
cast-iron for the first story fronts of business premises. Now, there 
were sometimes cases where the cost of a building was not the first 
consideration. In these the use of cast iron was to be carried a little 
further. There was no doubt of its fitness, as in no instance bad a 
cast-iron column or lintel been broken by an earthquake. The bear- 
ings and supports throughout the buildings were made wholly of this 
material. Brickwork was used in such a manner that, although the 
brick formed the bulk of the walls, the dependence or support was 
entirely with the iron ; the brick forming the muscles of the struc- 
tures, so to speak, and the iron the articulation. Iron girders and 
joists were introduced to support the doors, so as to render them, in 
some measure, proof against earthquakes, and also against fires. The 
cost of this system prevented its use, and few examples were built. 
A simpler system than any of these is now practised. The walls 
are built of brick, bedded in cement mortar tempered with lime so as 
to slow the setting, and also to bring it as nearly as possible to the 
consistency of the brick when set. The buildings are girt at the 
foundations, door, and roof with bond iron. These are complemented 
with the usual adjunct of hoop iron built in the brickwork. The 
flooring joists are broad and of more than the usual thickness, and 
carefully budged so as to be capable of resisting lateral thrust. The 
ends of the joists at intervals of five or six feet have anchors with 
cross-heads firmly attached to them, and these run through the walls. 
The same precautions are applied to the roofing timbers. It will be 
seen that these buildings mainly depend on the adhesiveness of the 
brickwork, which if properly executed will resist an enormous force. 
Brick chimneys are a fruitful source of danger in wooden build- 
ings, and in this earthquake of 186S the fact was well illustrated. There 
were whole rows of wooden buildings to be seen with the chimney- 
stacks chopped off at their juncture with the roofs, only proving what 
was known before — that the two materials having different periods of 
vibration, injury at their connection was sure to follow if not provided 
for in some adequate way. The stability of buildings is mainly due to a 
combination of strength and elasticity, and they must be constructed 
so that when a shock occurs they may vibrate as one whole. Having 
these considerations in view, and to ensure greater security in case of 
future disturbances, an iron tube the size of the flue is sometimes set 
up, and outside t hat another 4 inches larger ; the space between is 
then filled up with plaster of Paris, and from where the stack leaves 
the roof a moulded top of galvanised iron of any preferred form is 
fixed. Another method is to enclose the inner tube with brickwork 
and finish the exterior as usual. In the latter case the tube is formed 
with a thicker plate of iron. Both methods appear to fulfil the 
requirement. 
Prom California, let us return again to Italy, and hear what Dr. 
Johnston-Lewis has to say on the construction of buildings for Ischia 
after the earthquakes of 1881 and 1883 : — 
“ The destruction produced on buildings is due to their incapa- 
city to follow the earthquake movements. Their great weight as 
