FIRST REPORT OF COMMISSIONERS.

xxix

sasli bars and 896,000 square feet of glass were required for the roof, the aggregateweight of glass being about 400 tons.

The outer enclosure of the Building is formed by dividing the 24-fect spacesbetween the iron columns into three panels; those on the lower story are filled in

with boarding, in the upper stories with glazed sashes. Metal louvres lixed in

frames 3 feet high are introduced at the top of each story round the entire circuit ofthe Building, and in the lower story similar ventilating frames form a plinth of 4 feethigh immediately above the floor. The total ventilating surface thus obtained

amounts to 40,800 square feet, or very nearly one acre. (The results of the measures

taken to ensure the proper ventilation of the Building, will be seen by reference tothe return in Appendix No. X., which shows its temperature on eacli day duringthe Exhibition.) Each story is crowned externally with a cornice and crestingornament, and over the columns posts are carried up, to which flag-stalls were fixed.

Three entrances were provided, one in the centre of the south side, and one ateach end of the Edifice ; and in order to facilitate the egress of large crowds, 17other doors were provided for exit only. The lioor is entirely boarded; on theground lioor an interval of about half an inch is left between the boards to allowdirt from the feet to pass through; the Gallery floor, on the contrary, is closeboarded and tongued to prevent the passage of dust.

The roof of the transept Inis been mentioned as being semi-cylindrical insteadof flat like that of the remainder of the Building. This roof is supported by archedtimber ribs placed 24 feet apart, or one over every column, the tops formingsockets into the end of which the leet of the ribs arc fixed. Horizontal timbers orpurlines between these support minor ribs at distances of 8 feet, and upon these aridge and furrow roof is constructed in a manner similar to that already described,but following the curve of the arched ribs, instead of being worked on a horizontalplane. A narrow gallery is constructed along the ridge of the arched roof to affordaccess for repairs. The ends of the transept are filled in with Jim-like tracery andglazed sashes. The only portion of untransparent roofing in the whole Buildingoccurs on either side of the arched roof just described, where there is a lead flat24 feet wide, which afforded the opportunity of giving some additional strength toresist any tendency in the arched ribs to spread outwards at the springing.

It has been estimated that no less than 700 tons of wrought iron and 3,800 tonsof cast iron were used in the construction of this Building, as well as 600,000 cubicfeet of timber.

During the progress of the works many important additions to the Building, asoriginally undertaken by Messrs. Fox and Henderson for the sum of £79,800,were made. The quantity of ventilation was increased ; the galleries were doubledhi extent. The external railing, the gas-lighting, both external and internal,extra offices, staircases, and refreshment accommodation were provided, and a con-siderable extent of additional area was enclosed. The planing of the floor, theornamental painting, both inside and outside, the boiler-house and its connectionswith the main building, provisions of water for fountains, and increased provisions