CONSTRUCTION OF THE BUILDING.

69

On the ground being given up to the contractors, the first work undertaken Hoarding com-was the construction of a hoarding to inclose the whole area of the site. This up t°

hoarding was formed by the insertion into the ground, in pairs, of the timbers contracton "ultimately to be used as joists. Between each pair of uprights were slipped theends of boards, ultimately to be used as floor-boards ; and these were secured byattaching together the two ends of the joists extending above them. Thus theexpense of the hire of waste boarding was avoided; the timber composing thehoarding was completely uninjured; and the celerity with which the whole areawas surrounded was truly remarkable.

The task of setting out the plan of the building was intrusted to Mr. Brounger ; The setting out.and the extreme accuracy with which the situation of every column was fixed, andthe adjustment of every level was performed, reflects credit upon that gentleman.

In order that the measurement of 24 feet, upon which the accuracy of How proceededthe whole plan depended, might be indicated with extreme precision, poles of•thoroughly-seasoned pine were fitted with gun-metal cheeks, or small pro-jecting plates, the ends of the poles extending a few inches beyond the cheeks.

The measurements were taken by laying one pole on the other, so that the inneredges of the gun-metal cheeks, set at precisely 24 feet from one another, mightbe brought into contact. Thus the danger of any error, arising from the ends ofthe poles becoming damaged in use, was avoided. Stakes having been driveninto the ground to indicate approximately the position of the columns, theirprecise centres were ascertained by the use of the theodolite, and marked bydriving a nail into each stake at the exact point. When it became necessary toremove these stakes, in order to dig out holes for the concrete foundations, aningenious method was resorted to, for at any time identifying the position occu-pied by the nail which had been removed. To effect this a right-angled trianglewas framed in deal, at the two ends of which saw-cuts were made. Previous todie removal of the stake, the apex of the triangle was set to the nail indicatingthe situation of the centre of the column. Two other stakes were then drivenbeneath the saw-cuts, and two nails driven in at the ends of the saw-cuts. Thewooden triangle being then removed, the centre stake was withdrawn, the holemade, and the concrete thrown in. The height of the surface of the mortar,varying with almost every column, was regulated by pegs driven to the correctlevel under the direction of Mr. Brounger. Another triangle of a somewhatsimilar character to, and having saw-cuts in the same position as the one alreadydescribed, having two of its angles adjusted to the two stakes remaining in theground, determined the exact position in which the base-plates had to be fixed.

As every casting was delivered on the ground, it received a careful examina- Castings ex-tion, and an immediate coat of paint. The girders, upon the perfect soundness gWmpmteiof which the stability of the galleries and roof mainly depended, were subjected —ho " -to a rigorous test, m a machine arranged for the purpose by Mr. Charles Heard

ild. . One of Mr. Henderson’s patent cranes was so placed that, on a waggoncontaining girdcis being brought beneath its range, a girder was lifted from thewaggon and deposited upon a weighing apparatus. An account having beentaken o its weight, the girder was again lifted by the crane, and carried forwardto an extiemely strong frame, the two ends of which correspond in form anddnnemio ^ connecting pieces with their projections. The girder being

securely confined m these clutches, a force was exerted upon it. at the two pointsupon which the weight of the floors and roofing would have to be carried, that is