EARTHQUAKES — INFLUENCE IN BUILDING CONSTRUCTION. 767 
With respect to the security of foundations, Professor Milne has 
endeavoured to show by experiments how earthquake action may be 
partially avoided, either by making a seismic survey of the area on 
which it is intended to build, and selecting a site where the motion is 
comparatively small, or by adopting free foundations. But can we bo 
sure that a spot not much shaken by one earthquake will be as mildly 
treated by another ? There is this also to be considered : That where 
ground is cheap and plentiful, the selection of a site is never difficult, 
but in great towns or seaports, where business has centred in restricted 
localities, and the ground is required, we pay from £100 to probably 
£1,000 per front foot, and this regardless of the substratum. The 
problem to be solved is — how to erect a structure on any ground capable 
of withstanding the shock of an earthquake, such as L have described, 
and suitable for any purpose for which it may be built. I may shortly 
note here that the system of iron balls in the foundations to secure 
the safety of the superstructure might for a light isolated building be 
of some use, but for large structures much material and excellent 
workmanship will be required to make this plan effectual. For 
instance, there is the floor whereon the balls and whole weight of the 
building with all its contents are to rest. Over this and under every 
part of the building there must be a strong frame to w hich the cups 
to receive the balls are to be attached. All this would increase the 
cost enormously, besides which, as Dr. Johnston -Lewis points out, 
there is the u special uncertainty of action” to be encountered if in a 
city crowded with buildings. 
It appears to me that this paper would not be complete as an 
introductory document unless some brief but particular notice were 
taken of the Neapolitan earthquake of December, 1857, not only that 
it is classed as the third greatest in extent and severity of which there 
is any record in Europe, but because Robert Mallet, who had already 
distinguished himself in cosmic science, here applied those principles 
to Nature which he had already enunciated, and was afforded an 
opportunity of the highest interest and value for the study of this 
branch of terrestrial physics, lie wrote to the Royal Society of 
London offering his services, which were promptly accepted, and he 
was requested to proceed to Naples and make an investigation. 
lie explains that his observations were to have reference to two 
distinct orders of seismic inquiry — “ By the first to seek to obtain 
information as to the depth beneath the surface of our earth at which 
these forces (whether volcanic or otherwise) are in action, whose 
throbbiugs are made known to us by the earthquake, and thus to make 
one great and reliable step towards the knowledge of the nature of 
these forces themselves.” By the second “ to determine the modify- 
ing and moulding power of earthquakes upon the surface of our world 
as we now 7 find it ; to trace its effects, and estimate its power and 
extent upon man’s habitation and upon himself.” And these are the 
branches of seismology most important to architects. 
Let us briefly state how he succeeded in these objects. 
For the first order of inquiry he found a splendid field. He 
remarks that, “ in the chain of buildings for arriving at the angle of 
emergence from subnormal fixtures, those must be selected that are 
of larger size, with walls of brick, or of rubble masonry of inferior 
quality, or at least of small, short bonded stones, in proportion to 
