STRUCTURAL STEEL AND STEEL-FRAME BUILDINGS. 149 
mesh, etc., was used than with the double wrapping. But even the 
latter proved to be too weak and disintegrable to pass successfully 
through a severe earthquake or a fire and a strong stream of water 
from a fire hose. The plaster quickly cracks and falls away from the 
metal. No doubt these materials will be used in the future by owners 
demanding cheapness of construction, but they will satisfy the 
requirements only in cases of mild exposure. Good gravel concrete 
in place of the plaster, if of considerable thickness, has been found to 
give better results. 
The failure of the plaster and metal method and some other meth- 
ods of fireproofing in San Francisco is directly traceable to the 
commands of owners to their architects to cheapen as far as practi- 
cable the fireproofing and the construction generally, in order to 
receive greater interest on their investments. Much of this cheapen- 
ing has been done in spite of the protests of the designer, and it is 
in an entirely w T rong direction ; for rates of insurance are largely 
reduced with improvements in fireproofing, and as the cost of the 
steel frame and its proper fireproofing seldom exceeds 27 per cent 
of the cost of the building, it seems wise to protect the other 73 
per cent with adequate materials. 
BRICKWORK. 
In some buildings in San Francisco, brick laid in rich. Portland- 
cement mortar has been found to be an excellent fireproof covering; 
but it is objectionable on account of the bulkiness of the brick and 
the rusting of the steel, as in basement stories. Good brick withstood 
the severe fire well, and where laid in rich cement afforded a strong 
fireproof wall or pier. At least 4 inches of brickwork was found 
necessary, and a layer of concrete 3 inches in thickness between that 
and the steel was a great improvement and served well to protect 
the steel from rust. But this method will probably not be followed 
in general, on account of weight, bulk, 'and expense. Hollow brick 
and tiling were efficient also when properly and liberally used, porous 
tiles proving to be the better. 
The well-known Palace Hotel w T as built about thirty years ago, 
a few years after the earthquake of 1868, and before the introduction 
of steel-frame structures and concrete steel. It was intended to be 
earthquake proof as well as fireproof, and was built with very heavy 
walls of brick, most of them being 2 feet or more in thickness, laid 
in cement mortar, and strongly braced by many cross and partition 
walls. In the brickwork, at every 3 or 4 feet in height, were laid 
bands of iron, riveted together at their ends and crossings. This 
building, although of the old type, successfully endured the great 
earthquake, its walls being practically uninjured (PI, XXX, B) ; 
7171— Bull. 324—07 11 
