The lower storey of columns in every case stands upon base-pieces of which the upright portion is a continuation of the column, with "snugs" at the top, to correspond with those of the column, and standing on a horizontal bed-plate, from which "shoulders" rise to strengthen the upright portion. These bed-plates vary in size from three feet by two feet to one foot six inches by one foot, in proportion to the weight which the several superincumbent columns have to sustain. The longest dimension of the bed-plate is in the transverse direction of the building, in which the greatest overturning strain might be expected to act upon the columns. From the vertical portion of the base-pieces, sockets six inches in diameter project, in the direction of the length of the building, into which are fitted the cast-iron drain-pipes, which convey away the water brought down by the columns from the roof. The height of the base-pieces varies to suit the different levels at which the floor is supported above the ground. These levels had therefore to be determined in every individual instance previous to the castings being made. It was done, however, with such precision that, when they came to be used, they were all found to be of the exact length required for their situation. Of these base-pieces, 1,074 were required for the building. [Illustration: BASE-PIECE.] Cast-iron Girders. It has been mentioned that the columns supported girders at three different heights, dividing the greatest altitude of the building into three storeys; and that the lower tier of girders, where the building consisted of more than one storey, served to support a gallery. These gallery girders are all twenty-four feet long and three feet deep, the upper and lower "flanges" or rails having a [T section] formed section with standards at the ends of similar section. The rectangular space between them is then divided into three equal parts, by uprights having a [+ section] form of section, and the three smaller spaces thus obtained have diagonal "struts" in each direction. The girder thus described forms a double truss, in which the diagonal braces are subjected both to the strain of compression and tension. At the top and bottom of the end-standards small projections are cast on, by which the connecting-pieces hold the girders; and at each end of the flat portion of the top and bottom rails small sinkings are cast, by means of which the girder is keyed up to its position. The flat portion of the upper and lower "flanges" of the girder is swelled out in width from the ends towards the centre, in order to increase the quantity of metal in that part where the strain is greatest.