For constructing sidewalks over areas or vaults, concrete may, in most localities, be used to better advantage as regards quality and economy than any other material or form of construction, as the concrete not only furnishes the necessary strength, but also the finished walk.
* Mr. G. W. Percy, in Building.
Fig. 247 shows a section of monolithic sidewalk construction designed to obtain the maximum benefit from the glass discs built in the walk. No iron whatever is used in the construction of this walk, except for the twisted bars and the columns supporting the beam A. As such sidewalks are usually constructed a beam is placed under the wall to support the inner edge of the walk. This beam naturally obstructs much of the light dispersed by the glass discs. In the construction shown the weight of the sidewalk is supported entirely by the area wall, the beam A and the columns beneath. The beams B are made to act as cantilevers, ¼-inch twisted bars being imbedded in the top of the beams and crossways between the lights. The bars in the top of beams B are carried 5 or 6 feet beyond the beam A, and the beams B are placed opposite those marked C. The beams A and C have ¾ or 1 inch bars imbedded near the bottom to furnish the tensile strength.