FIRE-RESISTING QUALITIES OF STRUCTURES, ETC. 51 
of modern protective devices, and the prevailing high winds, made 
the probability feature alarmingly great. 
They advised that the inadequate force of four building inspectors 
be at least doubled, and that the building laws be rigidly and im- 
partially enforced. 
They found the fire department to be an efficient force, well organ- 
ized under an exceptionally competent chief, and though weak in 
powerful engines, otherwise fairly well equipped, the number of 
engine companies being particularly large. 
In their report the board summarized the situation in San Fran- 
cisco as follows : 
While two of the five sections into which the congested-value district is 
divided involve only a mild conflagration hazard within their own limits, they 
are badly exposed by the others, in which all the elements of the conflagration 
hazard are present to a marked degree. Not only is the hazard extreme 
within the congested-value district, but it is augmented by the presence of a 
compact surrounding, great-height, large-area, frame-residence district, itself 
unmanageable from a fire-fighting standpoint by reason of adverse conditions 
introduced by the topography. In fact, San Francisco has violated all under- 
writing traditions and precedents by not burning up ; that it has not done so is 
largely due to the vigilance of the fire department, which can not be relied upon 
indefinitely to stave off the inevitable. 
FIRE-RESISTING QUALITIES OF STRUCTURES AND STRUCTURAL 
MATERIALS. 
The fire which has practically destroyed San Francisco has more 
than fulfilled this prophecy. The destruction was greater than in 
the Baltimore fire because the fire was hotter, owing, as has been 
pointed out, to the inflammable surroundings and the unprotected 
openings, and to the unchecked sway of the flames. The heat was 
so intense that sash weights and glass melted and ran together freely. 
In some places the edges of broken cast-iron columns softened, the tin 
coating in piles of tinned plate volatilized, even in the middle of the 
piles, and nails were softened sufficiently to weld together. (See also 
PL LI, A.) The maximum temperature, lasting for a few minutes 
in each locality, was probably 2,000° or 2,200° F., while the average 
temperature did not exceed 1,500° F. 
Nearly all the so-called " fireproofs " were gutted and their con- 
tents destroyed, the fire damage done to these buildings being fully 
60 per cent. The early collapse of protected steel frames owing to 
the failure of the fireproofing was of common occurrence. The 
extent of the damage to a building from fire can be determined 
only after the debris and wreckage have been removed and will 
then be found to be much greater than was at first supposed. This 
is particularly true of steel structures in which the effect of fire is 
partly hidden by the debris. 
