Blind roaster

Besides firebricks, tiles made of similar refractory material are frequently used in furnaces and similar constructive work. They are particularly useful for covering spans of more than 6 inches, such as occur in flues and small fireplaces. Thus we have seen in Chapter IY. that the bed of a blind roaster is made of tiles, the reason for this being that we are thus enabled to make the flues wider. If we were to use ordinary or fire bricks for the purpose, we could not place the side walls forming the flue more than 5 or 6 inches apart, otherwise the 9-inch brick would not rest on them securely. By using tiles we can therefore span distances which are too large to be covered by brick, and too small to be covered by arches, or where, for other reasons, it would be inconvenient to use an arch. 

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