4 ANNUAL OF SCIENTIFIC DISCOVERY. 



these the largest that were ever made of sheet glass, each being 49 

 inches long. The iron-master passed his word, in like manner, to cast 

 in due time three thousand three hundred iron columns, varying from 

 fourteen and a half feet to twenty feet in length ; thirty miles of gut- 

 tering tube to join the individual columns together, under the ground ; 

 two thousand three hundred cast-iron girders ; besides eleven hundred 

 and twenty-eight bearers for supporting galleries. The carpenter un- 

 dertook to get ready, within the specified period, two hundred and two 

 miles of sash-bar ; flooring for an area of thirty-three millions of cubic 

 feet ; besides enormous quantities of wooden walling, louvre-work, and 

 partition. 



Dctails.of the Building. The celerity and rapidity of the movements 

 were much facilitated by Mr. Paxton's original details of measurement. 

 Thus everything in the Building is a dividend or multiple of twenty-four. 

 The internal columns are placed twenty-four feet apart, while the ex- 

 ternal ones have no more than eight feet (a third of twenty-four) of 

 separation ; while the distance between each of the transept columns is 

 three times twenty-four, or seventy-two feet. This is also the width 

 of the middle aisle of the building ; the side galleries are forty-eight 

 feet wide, and the galleries and corridors twenty-four. Twenty-four 

 feet is also the distance between each of the traverse gutters under the 

 roof; hence, the intervening bars, which are at once rafters and gut- 

 ters, are, necessarily, twenty-four feet long. The vertical supporters 

 throughout the building are" hollow cast-iron columns, eight inches in 

 diameter ; those on the ground floor being 18 feet high, and those between 

 the galleries and roof 16 feet. These columns have not the ordinary 

 circular form, but each length has four flat faces, standing in relief from 

 its surface, at intervals of 90 degrees. This plan is not only artistically 

 pleasing, but the several flat bands present surfaces best adapted for 

 the connection of the girders which support the roof and galleries. The 

 columns are hollow, and their thickness varies, according to the weight 

 they support, from f of an inch to Ij inch.^ The girders employed 

 were of cast-iron and wrought-iron. The cast-iron girders are employed 

 to span the spaces between the columns, and support the galleries. 

 They are three feet deep, and are cast open, with four struts or stand- 

 ards interposed between their upper and lower flanges, which divide 

 the rectangular space into three open frames, each of which is inter- 

 sected by diagonal trusses. The introduction of wrought-iron into the 

 construction of the roof was necessary in spanning the side aisles of 48 

 feet, and the nave of 72 feet, for which purpose its greater strength 

 rendered it preferable. 



Construction of the Building. One of the peculiarities of the build- 

 ing was, in its being its own scaffolding, or very nearly so. As fast as 

 the columns were raised, they were joined with the girders by connect- 

 ing pieces, or lengths of columns equal to the depth of the girders, 

 which are furnished with the projections requisite for securing them 

 firmly in their places. These connecting pieces terminate in castings 

 adapted to receive the girders, and consisting of perforated flanges, cor- 

 responding with those cast in the ends of the columns ; and, these 

 being paired, a bolt was passed through them, and made fast by a nut 



