IRON MANUFACTURE. 525 
thin walls in the hearth and boshes, which are protected from destruc- 
tion or from over-heating by means of coil-pipes through which water 
flows, is very general, and is shown in the new furnaces of the Cleve- 
land Rolling Mill Co. at its greatest development, and the probability 
is that this in some cases may be carried too far, some trouble having 
been experienced in some of the newer furnaces from the tendency to 
yield and crack from the pressure and heat of the charge. 
The arrangement of the upper part of the lining is practically the 
same everywhere, consisting of the interior of fire-brick separated 
by a narrow space from an exterior shell of common or red brick, 
placed next the mantle of the furnace; the space between the fire- 
brick and the red brick, as well as the space between the red brick and 
the mantle, is frequently filled with clay or sand, the object of these 
spaces being to permit the expansion of the lining when the furnace is 
heated. 
Tn all these furnaces the lining of the shaft or upper part is sup- 
ported by an iron lintel resting on iron columns; in the majority of 
cases these columns are circular, made of cast-iron and from 18 to 20 
inches in diameter; the height of the columns, varying with the dimen- 
sions of the furnace, may run from 9 to 10 feet to, as in the case of the 
furnace figured, 25 feet, the more moderate dimensions being those 
usually found. 
The substitution of wrought-iron riveted columns for cast-iron, 
found in some cases, gives more lightness with the same strength, an 
arrangement shown in plans of furnaces by Witherow & Gordon and 
the Weimer Machine Company, and other recent designs. 
The foundation and sole of the blast furnace is masonry, generally 
carried down to considerable depth. ‘The sole proper of the furnace is 
built of fire-brick of large size, and occupies a cayity in the stone foun- 
dation corresponding in diameter to the size of the furnace. 
The way in which these bottom brick are set is usually on the plan 
of a flat inverted arch, being set obliquely from the sides in, and keyed 
by a cone-shaped central brick, the object of this arrangement being 
to prevent the bottom from lifting, which would certainly take place 
under an upward pressure produced by the melted iron around the 
brick. Sometimes the brick are made with angles, so arranged that 
each brick catches in the one next to it by a lug. In some cases the 
sole is made of sandstone instead of brick, where obtainable of good 
quality. 
