156 THE SAN FRANCISCO EARTHQUAKE AND FIRE. 
Double windows of wire glass in hollow metallic frames are recom- 
mended, or where such material would be objectionable by cutting 
off the view, double plate glass is considered next best. Interior 
doors should be of metal, or at any rate metal covered, in fireproof 
buildings, and the light for corridors and halls should come through 
wire glass. As the installation of wire glass, metallic rolling shut- 
ters, and metal sash involves only a small percentage of the cost of 
the building, and as these materials have proved to be of such excel- 
lent service as fire protection when of the best quality and workman- 
ship, a wise economy demands their use in every important fireproof 
building. 
Capitalists and owners must understand that perfect fire protection 
for structural steel is necessarily expensive. Any so-called fireproof- 
ing that is cheap and flimsy is a delusion and will not serve. The 
application of an effective method insures permanence of the struc- 
ture and at the same time greatly reduces the rates of insurance. 
Steel columns may be well fireproofed by surrounding them with the 
best quality of stone or cinder concrete 4 inches in thickness, or by 
3 inches of either when hollow tiling is put on the exterior. 
A 3-inch porous terra-cotta tiling, wrapped on the outside with 
wire, and with metal mesh used around the bed course of the column, 
has proved efficient. The mortar of the tiles should contain a large 
proportion of cement, and the tiles should be strongly anchored to the 
columns to prevent their falling away in earthquake or fire and so 
leaving the steel exposed. 
In the great fire, decorations, trim, inflammable oil paints and 
varnishes, in office buildings, aided materially in spreading the flames. 
A noninflammable water-color paint that will endure washing has 
been recommended. 
Fire walls of brick, extending above the roofs of buildings, were 
effective in resisting the spread of the fire; but the support derived 
from metal bands and anchors was neglected in many such walls, 
as in much other masonry in San Francisco; a large number of them 
fell, therefore, during both the earthquake and the fire, particularly 
those laid in common mortar. This was also a common fate of 
unsupported gables and towers. Walls that were well anchored, as 
in the Union Trust Building, remained in perfect condition. 
Cast-iron columns in some buildings endured the earthquake and 
the fire fairly well, but undoubtedly would have been broken or 
shattered had cold water been thrown upon them in the midst of the 
great heat. They should no longer be used, for at present they cost 
more than steel for an equal factor of safety, and their connections 
are clumsy and weak. 
Structures made of concrete blocks were as a rule greatly damaged 
