THE MINING AND QUARRY INDUSTRY I9I3 21 



where the temperature does not rise high enough for the thorough 

 vitrification required in paving brick. They are never repressed and 

 the roughened surface is secured by means of a wire placed near 

 the die of the machine so that it drags over the surface of the 

 clay ribbon as this comes from the machine. The dry-pressed front 

 brick constitute the fourth class. All varieties are burned in cir- 

 cular or rectangular down-draft kilns. The total production of 

 front brick in 1913 was 9,355,000 valued at $99,736, a slightly 

 smaller number than was reported for 1912. 



COMMON HOLLOW BRICK 



The common hollow brick were made by nine producers last year 

 who reported an output of 7,631,000 valued at $44,265. The meth- 

 ods of manufacture are practically the same as those used for hol- 

 low building blocks. Clays or shales are employed in a stiff mud 

 machine, the brick being end cut. At one place the bricks are 

 formed with a tile press. There are two forms — headers and 

 stretchers. They are used chiefly for the construction of an inside 

 veneer over common building brick or fi reproofing. The demand 

 comes mostly from the larger cities and is supplied in most cases by 

 local plants. 



FIREPROOFING 



Fireproonng, which has come into such favor among architects 

 T-nd builders during late years, has had in the State of New York a 

 fairly constant growth since 1907. As reported to this office, the 

 product is known under the various names of terra cotta lumber, 

 fireprcofing, hollow tile and hollow buildmg block. • It includes 

 m.any different shapes and sizes that are used in the construction of 

 side walls, floors, arches and partitions, but not common hollow 

 brick. This last article is used mostly as a veneer and not in the 

 main construction. The shapes and sizes of the blocks vary, though 

 it is the usual case to make one face with an area of one square foot. 

 The product is sold mainly by the ton, but in small construction work 

 the prices may be quoted by the square foot. The number of air 

 spaces varies from one to nine. 



On account of fire protection, comparative great strength, low 

 repair costs, low first cost as compared with the present prices of 

 lumber, and its control of sudden changes in outside temperature, 

 the product has lately been used to a great extent as a material in 

 the construction of private dwellings. Faced with cement, stucco or 

 a veneer of front brick, a building of this material is practically in- 



