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be made to form an arch with concave soffit, as shown in Fig. 121, the ceiling in which presents the same appearance as an ordinary brick arch.

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This class of construction possesses good fire-proof qualities, is economical in space and weight, as well as reasonable in cost, and it can be safely used in all arches of moderate span, where bricks can be employed alone for fire-proof purposes, and in many places where bricks cannot be so used, without requiring large space and much needless expense.

Hollow tiles as well as solid may also be applied to fireproofing iron and other columns, the disastrous collapses of

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unprotected cast-iron supports during great fires being what has demonstrated the great necessity for a non-conducting material to protect them when they are employed.

In Fig. 122 A and B are perspective views of encased iron columns, one a cylindrical and the other an X-shaped support.

The first is covered with 2-inch hollow tile, laid in cement mortar, and firmly tied around all sides of the column with tile clamps; the air space in the tile being a great help during the heat of a conflagration. The X-shaped column is encased with a solid tile, a sectoral air space being secured between the column and tile.

In this case the tile does not project so far beyond the face of the column, which allows the proportions to be more properly observed, and besides it is cheaper and just as effective.

The tiles are laid so as to break the bond or joints, and are entirely self-supporting, no drilling or tapping of the column being required.

The cut also shows the usual ways in which the columns are finished after the covering is in place, Portland, Keen's, or Parian cement being the ones usually employed. Sectional plans of the encased columns are shown at C and D. Sectional views of E and F show variations in the form of fire-proof casings.

NOTE. For a portion of the matter contained in this chapter, relating to English fire-clays, the author desires to acknowledge his indebtedness to an excellent article on the subject in the Encyclopædia Britannica, 9th edition, vol. ix. p. 238.

CHAPTER VII.

TERRA-COTTA.

SECTION I. GENERAL REMARKS.

TERRA-COTTA is but another name for architectural enrichments of brick-work of various designs and shapes. The term is of Italian derivation, and, literally translated, means cooked or baked clay. This term was more appropriate to the ancient terra-cotta, which was usually less burned, not so homogeneous and coarser in texture than with us, but that is not a true description of the process as now employed in converting the artistically moulded clay into finished terra

cotta.

From the definition, cooked or baked clay, it might be supposed that terra-cotta did not receive so great a degree of heat as is applied to bricks during the process of burning; but this is not true, as terra-cotta requires a greater degree and a more regular distribution of heat during the firing than are either given or generally required for bricks.

The reason for this is that less lime and alkaline fluxes are contained in terra-cotta clays than in brick-clays, and the former being stronger and more refractory, naturally require greater heat to compel them to part with the water chemically combined with them.

Terra-cotta was largely used for architectural decorations

in Greece, Etruria, Pompeii, Rome, and Mediæval Italy, and it was in the clay plains of North Italy that terra-cotta was first predominantly employed over other materials in architectural construction and ornamentation, and the inspiration of modern designs in architectural terra-cotta is largely drawn from these works, especially those structures erected from the middle of the thirteenth until the commencement of the sixteenth century.

In England, the friezes, cornices, and other highly ornamental work in terra-cotta of the Manor House at East Barsham and the Parsonage House at Great Snoring, both in Norfolk, erected during the reign of Henry VIII., are worthy of particular notice, and the use of terra-cotta for decorative panels and bas-reliefs appears to have been popular during his time.

The gateway of York Palace, Whitehall, designed by Holbein, was decorated with four circular terra-cotta panels, which are still preserved at Hatfield Peveril, Hants.

The gateway of the Rectory of Hadleigh Church, Suffolk, erected at the close of the fifteenth century, was very carefully restored about thirty-five years ago, the terra-cotta for the purpose being creditably reproduced, at the Lyham Kilns, near Hadleigh.

From the latter part of the fifteenth century until after the reign of Elizabeth, terra-cotta was used only in large and expensive buildings; but at the beginning of the eighteenth century the use of terra-cotta was by no means uncommon in Great Britain; but soon after the reign of Queen Anne its use was discontinued. Its modern employment is but a

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