58 THE SAN FRANCISCO EARTHQUAKE AND EIRE. 
per square inch. The writer believes that the higher figure should be 
used, because the essential in satisfactory earthquake-resistant design 
is rigidity, whereby the structure moves as a unit. Unless there 
should be earthquakes of greater severity than the one under discus- 
sion, no fear need be felt for tall buildings. It has been fully 
demonstrated that a steel frame well braced diagonally upon an 
adequate foundation successfully meets the earthquake requirements ; 
not even the masonry being injured to any great extent. 
Concrete, especially reenforced concrete, because of its great ad- 
hesive strength and reenforcing metal, proved more satisfactory 
than any other material. Its solid monolithic structure produces a 
successful earthquake-resisting material, inasmuch as it moves as a 
unit; moreover, it offers a maximum resistance to fire. The great 
concrete dam of the Crystal Springs Lake at San Mateo (PI. XI, B) 
gave abundant proof of the substantial qualities of concrete in a mass, 
for although it lies within a few hundred yards of the fault, it 
suffered no damage. Solid concrete floors proved satisfactory, 
though concrete in San Francisco was of a very poor quality, and 
flimsy concrete stiffened with light metal passed as reenforced con- 
crete. Cinder concrete was used extensively for floors and elsewhere, 
and was of a very inferior grade. Much of it was high in sulphides, 
which had a deleterious effect on the embedded material, especially 
in floors where slight cracks permitted air and moisture to come In 
contact with these sulphides and the metal. For a proper earthquake- 
proof structure, everything — the design, the materials used, and the 
workmanship — must be first-class. Most of the failures resulted 
from bad design, poor workmanship, and poor materials. If reen- 
forced concrete of the quality described could give such satisfactory 
results in meeting the extraordinary conditions of the San Francisco 
earthquake and fire, it is evident that much greater satisfaction would 
have been given by the use of first-class material. 
The causes of the failures in San Francisco may be summarized 
as follows: 
1. The effort on the part of those qualified to design and advise on 
building construction to meet the owners' demands by planning 
structures so that they can be erected for the least possible cost, a 
practice which tends to a departure from the principles of correct 
design, the result being a structure that will carry ordinary loads, 
but that fails when subjected to unusual conditions. Such Avas the 
case at Stanford University, where the poorly constructed stone- 
veneered buildings met ordinary conditions, but failed in the earth- 
quake; while the more substantial structures, like the dormitories — 
one of reenforced concrete and the other of solid stone masonry — 
survived. 
2. Actually dishonest design and construction. 
