REPORT OF THE ARCHITECTS. loiJ 



8. Covering of the flat roofs. — These metal roofs are supported prima- 

 rily by tlie wrought-iron trusses laid 13 feet between centers ; these 

 again are subdivided and cross-laid by wrought beams of lighter sec- 

 tions so as to cut up the ceilings into spaces of 4 by 13 feet in size. At 

 the suggestion of General Meigs these spaces were bridged by gratings 

 formed in two thicknesses of light tapered wooden strips and fire-proofed 

 by being filled in and inclosed with a non-conducting mixture composed 

 of plaster of Paris, lime, coal-ashes, and cinders. Before actual use we 

 have made ample tests in order to reduce the weight of the gratings and 

 of the composition to a minimum, and on the other hand to increase its 

 rion-conductibility. The greater part of this work is done and the metal 

 laid upon it iu sheets of 14 by 20 inches in size, having flat joints. Each 

 sheet is clamped down to the gratings by eight clamps of sheet metal, 

 two on each side, in such a manner that each sheet, independent of all 

 others, can expand and contract, which in such large roofs is an im- 

 portant consideration. 



9. Wooden floors. — All the flooring required has been secured of 

 Florida yellow pine, by contract, at very reasonable terms. 



10. Plastering. — No scaffolding material being kept on hand by the 

 tradesmen for reaching high walls or ceilings of buildings like this, the 

 poles and lumber of the scaffolds for the brick- work were purchased at a 

 reasonable rate from the contractors for that branch and are now on hand. 



11. Glass, glazing, and painting. — With the sudden stimulus which the 

 industries of this country received last fall, home-made glass came to 

 be a scarce article, as the proposals received under extensively published 

 advertisements show ; the lowest bids were for Belgian glass, imported 

 free of duty, with the approval of the Treasury Department. This glass 

 is shortly expected to arrive, after which the sash will be glazed at an 

 early date. The painting has so far been mostly confined to the metal 

 cornices and piping, the iron- work and window-frames having been fur- 

 nished, by the respective contractors, all primed. 



12. Carpenter's icork. — This has so far been mostly directed to the 

 making of roof-gratings, described under another head. But, besides, 

 a large amount of centers has been made and put up for turning arches 

 in the brick-work and floor-arches. In the concrete above the floor- 

 arches the thin sleepers have been laid to which the flooring is to be 

 nailed. The setting of door-jambs is about to be commenced and to be 

 followed by all the minor details required for getting the building in 

 readiness for the plasterer 



13. Sewerage, drainage, and plumbing. — In the early part of the spring 

 the main sewer on B street was cut out and a 12-inch glazed terra 

 cotta sewer connected with it for the drainage of the new building 

 The numerous branch sewers within the building leading to some sixty 

 conductors from the roofs, and to soil-pipes of closets and basins, were 

 under a decision of the commission delayed until the completion of the 

 Avails, but have lately been completed, as also most of the extra heavy 



