CLAYS OF NEW YOEK 677 



regards the price of fuel. The great majority of the yards along 

 the Hudson use wood, a few use coal and two or three use oil. 

 With coal and oil the heat can be better regulated than with wood. 

 Another important point is the amount of pale brick produced. In 

 scove-kilns there is sometimes a loss of as much as 50,000 to 75,000 

 in a clamp of 500,000 bricks, while in a permanent kiln such as the 

 Wingard or one similar, the amount of pale brick is said to be not 

 usually over 25,000. Again in the case of permanent kilns, it 

 takes no more, if not less, time to set the bricks and there is less 

 daubing to be done. Regarding the amount of labor required in 

 burning, one man is supposed to tend three arches. 



TTp-draft permanent kilns. These differ from scove-kilns only 

 in having permanent side walls. They are open at the tops and 

 ends, and the latter have to be walled up before the burning com- 

 mences. Kilns of this type are used to a large extent for burning 

 common brick, but they are little used for front, stock, or orna- 

 mental brick, as the percentage of salmon brick produced usually 

 amounts to from 20^ to 35^. The brick are set in the same man- 

 ner as in scove-kilns, and the burning proceeds on the same 

 principle. 



In up-draft kilns the bricks forming the arches are exposed 

 to the direct action of the flames, and are usually overburned, so 

 that they are twisted or crushed out of shape, and often covered 

 by a layer of ashes which have stuck to their surface. They are 

 known as " arch " or " eye " brick. The salmon brick are gen- 

 erally to be found in the upper courses of the kiln, and they together 

 with the arch brick may at times form an appreciable percentage 

 of the product. 



Up-draft kilns are cheaper to construct, and easier to keep in 

 repair than the down-draft kilns, for the latter have the bag walls 

 on the interior and usually an arched roof, both of which require 

 constant attention, and at times may necessitate expensive repairs. 



Down-draft kilns. In these the fire is conducted along the in- 

 terior to the top of the kiln by means of bags, or " pockets " as they 



