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stories, consist of glass in wooden sash-frames, inserted between columns 8 feetfrom centre to centre, and louvre frames for ventilation, surmounting the sash- 'frames. On the ground story, boarding takes the place of the glass; and theheight being 24 feet instead of 20 feet, an additional tier of ventilators isinserted. The columns at 24 feet apart being of iron, the intermediate ones,dividing that width into 8-feet compartments, are of wood.
As no less than 1,500 sash-frames have been used, they may justify a few The sash-frames,words of description. To quote again from the “Transactions of the Institution ofCivil Engineers, ” we learn that “ the sash-frames are 2^ inches thick, with seven“bars in their width; the bars being 2| inches deep, double grooved for glass.
“ W rought-iron bolts, f inch diameter, pass completely through the sash-bars and“ sash-frames, at the points where they are attached to the columns ; and thus a“ chain tie is kept up all round the building, in order to prevent displacement of“ the sashes, either bodily or in portions, by the pressure of the wind. To further“guard against the same action, timber bridges, 3g inches by 1£ inch in the centre,
“are fixed across the middle of the length of the sash; and at the internal“ angles, where the wind will exert its greatest force, iron rods, half an inch in“ diameter, are fastened from column to column, pressing against the wooden“ bridge, and converting it into a continuous strut, bearing up against any force“applied to the exterior of the sash. In order to glaze the sashes, the glass“is slipped, down between the bars, and provision is made for mending, by“ causing one groove to be cut deeper than the other, so that the glass may be“ slipped in from one side, and puttied into its exact place. A similar pro-“ vision is made for mending the roof glass.”
As whatever lateral force the wind may exert upon the building will be The action of
• • Ti . , . n . J « . L . • * 1 * wind on them,
principally received, by these sashes, it may not be inappropriate, m considering ami on the nuii.i-tliem, to advert briefly to the general question of the action of wind upon the ms ’building.
On the 15th of January, 1851, a meeting was held at the Society of Arts, atwhich Mr. Fox, one of the contractors for the building, attended, to afford themembers of that Society an opportunity of asking any questions as to the generalpoints of stability and durability on which they might desire information.
One of the questions proposed was, “ What would be the effects of the wind i, ow described by“ on such an extensive surface as the building presented, and what means were Mr ' l ' ox '
“ taken to counteract them?” and as Mr. Fox’s reply embraced with remarkableclearness the principal facts connected with the argument, we shall give it atlength, Mr. Fox replied “ that the building rested on 1,060 columns on theground floor, and the most likely direction for the wind to have any injuriousettect on the building, must of course be in the direction of its greatest width,tt was 1;800 feet as compared with 400 in the opposite direction. These
(( c ?.. umn * rest ® c l on cast-iron plates based upon concrete ; and there was no possi-t( 1 0 roc king about without the base-plates being broken. Above
{ tiese p ates were sleepers, that carry the floor. They were 13 inches in depth,
“ and fitted accurately up against the two sides of the column, and runningtransverse y rom one side of the building to the other; so that it woulde very i cu t to conceive that one of these columns could be possibly upset“until it was actually broken in two. And again, at the top the columns are“ united together by cast-iron girders 3 feet deep, and four columns are framed“ together, very much as they would frame a tabic. Now, to break the column,
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