We have now traced the erection of the building up to the level of the roof, in which it will be readily conceived the operation of glazing was one of extreme difficulty, there being no scaffolding to aid the workmen in conducting their operations. When the glazing was first commenced a light scaffolding was suspended from the rafters; but this was found to be too tedious and troublesome a method of proceeding for so large an extent of roofing. It was, moreover, of great importance that some means should be devised for completing this part of the construction independently of the weather; a matter of some moment, when it is remembered that the work had to be done in the winter, when in our climate such operations are liable to be very much impeded by heavy rain. The arrangements made to meet this difficulty, as well as some others for carrying on the works, are very clearly described in a paper by Mr. Digby Wyatt, read at the Institution of Civil Engineers, on the 14th January, 1851, from which we quote some passages, by permission, for the benefit of our readers. With reference to the means employed for glazing the roof he says: "To effect this purpose, a travelling stage was devised by Mr. Fox, which superseded the necessity of any scaffolding for glazing, and by means of seventy-six of these machines nearly the whole of the work has been executed. The stage was about eight feet square, and rested on four small wheels travelling in the Paxton's gutters. It thus embraced a width of one bay of eight feet of the roof, with one ridge and two sloping sides. Each bay in width required, therefore, a separate stage." "Each stage was occupied by two workmen, and was covered by an awning of canvass stretched over hoops, to protect them in bad weather, and was further provided with a box on each side to contain a supply of glass. The sash-bars and other materials were piled upon the stage itself, the centre of the platform being left open for the convenience of hoisting up materials, for which purpose there was a small iron arm with a single block pulley." [Illustration: GLAZING-WAGGON, FOR FLAT ROOF.] "Whilst working, the men sat at one end of the platform (the ridge having been previously fixed in position by means of the extra-strong sash-bars), and they fixed the glass in front of them, pushing the stage backwards as they completed each pane. On coming to the strong sash-bars previously fixed, they temporarily removed them to allow the stage to pass. In this manner each stage travelled, uninterruptedly, from the transept to the east and west ends of the building, and the glaziers were enabled to follow up the previously-fixed work very closely. The average amount of glazing done by one man per day was fifty-eight squares, or about 200 superficial feet; and the largest amount done by any one man in a working-day was 108 squares, or 367 superficial feet."