EARTHQUAKES — INFLUENCE IN BUILDING CONSTRUCTION. 765 
In the case of vorticose earthquakes the earth is whirled round 
and back in something like the motion describing the figure 8. The 
most conspicuous example of this kind was the great Calabrian 
earthquake of 1783. In it the blocks of stone forming obelisks were 
twisted one above another. The earth was broken and twisted, so 
that straight rows of trees were left as interrupted zigzags. This kind 
of motion was observed, too, in the earthquake of Eiobamba already 
referred to, and also in a mild way in the Californian earthquake of 
In order that the buildings to be erected in regions where earth- 
quakes occur, whether for public or private use, may be steadfast, suitable 
for their purpose, and such that the occupants may have a positive feel- 
ing of security — notwithstanding any movement (which is inevitable) 
that the buildings may have while uuder earthquake influence — to the • 
people of these disturbed regions must ever be an important problem. 
By continuing the investigation we may hope to arrive at a solution in 
the discovery of a mode of construction to at least secure perfect safety 
from the effects of these so-called horizontally progressive earth- 
quakes. Happily for mankind, the explosive and vorticose examples 
are of rare occurrence. 
It has always been recognised that to secure steadfastness the 
foundation of a building plays an important part. Thus Vitruvius 
says: — £ ‘If ground be loose or marshy, the place must be excavated, 
cleared, and piles must be driven with a machine as close to each 
other as^ possible, and the intervals between the piles filled with 
charcoal.” This, he says, will carry the heaviest foundation. I 
cannot find that he used any precautions against earthquakes. 
Pliny implies that the Greeks studied the effects of earthquakes 
upon buildings. Thus in his description of the Temple of Diana, at 
Ephesus, he tells us that a marshy soil was selected for its site, in order 
that it might not suffer from earthquakes or the chasms which they 
produce ; and that the foundation of so vast a pile might not have to 
rest upon a loose shifting bed, layers of trodden charcoal were first 
placed as a foundation, and fleeces covered with wool were then laid 
upon the top of them. 
This looks like a reliable account, but scarcely agrees with Woods 
in his work on “ The Discoverer at Ephesus.” He, having Pliny’s 
description in view, and to test the accuracy, caused holes to be sunk 
in different places, and found a layer four inches thick, and below 
that another layer of putty-like composition. This, when analysed, 
was found to consist of carbonate of lime, 65*91 ; silica, 26T0 • water, 
&c. (volatile), and a trace of nitrogen, 7*99 ; so that, in fact, there 
was nothing but a species of mortar. 
In Pliny’s chapter, under the head of “ Preservation against Earth- 
quakes,” he says : — “ Where there is a number of caverns they afford 
a protection, as they give vent to confined vapours, which has been 
proved in certain towns which have been less shaken when they have 
been excavated by many sewers, and in the same town those parts that 
are excavated are safer than the other parts, as is understood to be 
the case in Naples, the part of it which is solid being more liable to 
injury.” He also tells us that “ the capitol of Eome was saved by 
