136 THE SAN FRANCISCO EARTHQUAKE AND FIRE. 
walls. Such walls commonly collapsed, and the brick were found 
afterwards with dry, clean surfaces, the mortar having no adhesion. 
(See PL XXI, A.) On the other hand, walls that had been laid 
in Portland-cement mortar, with brick thoroughly wetted and all 
parts well bonded together, stood the trial perfectly and are stand- 
ing to-day. 
Tall, steel-frame, stone-exterior office buildings of the class A type 
that were founded either on well-driven piles or on concrete slabs 
suffered no very serious injury by the earthquake. With the excep- 
tion of a crack here and there in a stone pier, arch, or stairway, or a 
block of veneer loosened or dropped from a front, they remained 
entirely serviceable, so far as the earthquake effect was concerned. 
An excellent example of this class of buildings, and one that is 
exceedingly instructive, as it passed through the earthquake but 
escaped the fire that ravaged San Francisco, is the Union Savings 
Bank, in Oakland, at the corner of Broadway and Thirteenth street. 
This building is a steel-frame, stone-veneered structure, having 11 
stories and a basement. It is founded upon separate concrete blocks 
and piers which rest upon a strong soil of mixed sand and clay. This 
structure was practically uninjured. 
Buildings in San Francisco which rested upon foundations of sand 
in natural place were not injured by the shock, except where the sand 
was on a hillside or had opportunity to spread and flow. In such 
places buildings of either masonry or wood were badly shaken. 
Where the buildings rested upon good, hard soil, as on the hillsides 
or summits, practically no injury was done with the exception of the 
loss of chimneys and, in some buildings, of plaster. A first-class 
building of stone, brick, concrete, or steel frame in such situation 
seems absolutely proof against any earthquake of no greater severity 
than the one under discussion. 
THE FIRE. 
GENERAL DESCRIPTION. 
Immediately after the first shock of the earthquake sixteen alarms 
of fire, from widely separated localities, were turned in to the central 
station. The causes of these fires were directly traceable to earth- 
quake effects, such as the upsetting of oil lamps and oil and gasoline 
stoves, the contact of combustible material with lamps and gas jets, 
the rupturing of chimneys and flues, the scattering of chemicals, such 
as phosphorus, and the upsetting of boilers, furnaces, etc. It is 
claimed that currents of electricity did not originate any fire. Either 
the generators were disabled or the attendants switched off the 
currents. 
