266,166. Robertson, T. E., (Power Specialty Co.). April 10, 1926. Walls; linings; cooling.- In a fluid-cooled furnace wall comprising bare metal tubes e, Fig. 3, having substantially vertically disposed body portions and transverse wall - penetrating end portions connected to external inlet and outlet headers E<1>, E<2>, plate metal ribs or fins K are welded to the convex side of the upper elbow portions of the tubes c and refractory material M fills the spaces between adjacent ribs. The material M may be fire brick or tile. but preferably is a " plastic firebrick " composed of ground firebrick and a clay binder, so that it may be placed in position in a plastic condition and set rigid by the heat absorbed from the furnace. The upper edges of the ribs K extend into contact with an overhanging bridge wall A<2>, their front edges are substantially flush with the front of the wall, and they may have registering apertures to receive horizontal reinforcing bars L. Whilst the tubes e are straight perforated cast-iron blocks E<5> may be shrunk in position, and, after the end portions have been bent, iron sections E<6>, E' may be cast in position, and to prevent deformation stiffening bars F may be connected by bolts to lugs welded to the backs of some of the blocks E<5>. Platelike iron or steel ribs I mav be welded to the under sides of the horizontal upper end portions of the tubes e so as to support them on an I-beam G on the top of a wall A<3>, the tubes passing through transverse beams H supporting the bridge wall A<2>. Alternatively the beam may be replaced by an angle-bar P, Fig. 7, bolted to the upper cast-on section E<6> and resting on a metal plate Q arranged between the wall A<3> and a masonry portion A<31>. The lower ends of the tubes e pass through transverse beams h and sufficient clearance is left between the lower caston section E' and the subjacent portion A<30> of the wall A<3> to allow of expansion and contraction of the tubes. Gas leakage may be prevented by a packing O of kieseiguhr or a yielding cement composed principally of mineral wool, asbestos, and a suitable binder. In the form shown in Fig. 8, the end portions of the tubes e pass through perforations in open cast-iron boxes HA, ha having central webs for retaining in position packing O<1> which may be similar to the packing 0. The boxes HA are supported by beams GA and the boxes have cover plates HA', ha<1> for supporting respectively the bridge wall A<2> and a short wall A<3>. Gas leakage is prevented by an outer layer R of refractory cement which also may be similar to the packing O. When adjacent tubes c and casing members are separated by any considerable distance, such as when the outlet header E<2> is divided into sections, the intervening space may be filled with material HA which may be similar to the material M, and which may be reinforced as by means of a bar S suspended from one of the bars L and centred bv means of bars S<1>. In a further form shown in Fig. 10, a packing RA, which may be similar to the packing O, is arranged between the back of the tubes and an outer metal sheathing. The lower casing blocks E<7> rest directly on the portion A<30> of a masonry wall A<3>, and the welded ribs KA project above the lower edge of the wall A<2>.