THE

ANNUAL OF SCIENTIFIC DISCOVERY.

MECHANICS AND USEFUL ARTS.

THE GREAT INDUSTRIAL EXHIBITION OF 1851.

PROMINENT among the events which have signalized the progress of Science and Art in the course of the nineteenth century, has been the "Great Industrial Exhibition of all Nations," during the year 1851. The conception of the scheme might have originated in any age; its realization could have belonged only to our own. The time, the location selected, the condition of the civilized world, all were propitious to the undertaking; and its results have surpassed the expectations of its designers. A friendly confidence among rival States, a feeling of perfect security, a freedom of commercial intercourse among all nations, facility and cheapness of transportation, the perfection of inventions, and the multiplication of practical applications-all these conditions, as they exist now, were requisite for the success of the Exhibition. That its results have been in the highest degree beneficial, in the diffusion of intelligence, promotion of good taste, and the cultivation of friendly intercourse among different people, none can doubt.

The Exhibition has existed and passed away, but it will remain in history as an exposition and true exponent of the progress and degree of development to which the civilized world had attained, in all branches of science and art, at the close of the first half of the nineteenth century.

In the following pages we propose to present a succinct and intelligible account of the origin, plan, and construction of the Crystal Palace, with the general history and details of the Exhibition.

First Building Proposed. The Exhibition having been fully determined upon, and a site for the necessary building chosen, the Committee advertised for plans for a suitable edifice. In accordance with their wishes, 245 designs from different architects were submitted, none of which, however, were entirely satisfactory. A design was then composed by the Committee themselves, founded upon the most approved

plans submitted. The building thus proposed was to have been 2200 feet long, 450 feet wide, with a huge dome, larger than that of St. Peter's at Rome. The roof and dome were to have been of iron, and not less than fifteen million of bricks were to have been used in the construction of the walls. This design, although at one time fully determined upon, was most violently opposed, both on account of the injury it would do the location, and the almost necessary permanence of such a huge brick and mortar edifice. To such an extent did the objections to the composite design of the Building Committee prevail, that the practicability of the Exhibition itself was jeopardized, when, fortunately, a new design was submitted.

Paxton's Improvements in Horticultural Buildings. Among the practical men to whom the first design appeared objectionable, was Mr. Paxton, the celebrated horticulturist of the Duke of Devonshire's princely seat of Chatsworth. Mr. Paxton had already effected many improvements in horticultural buildings, by discarding, as much as possible, all ponderous and opaque materials in their construction. He pared away all clumsy sash-bars, whose broad shadows robbed plants of the sun's light and heat during the best parts of the day; he abolished dirty and leaking overlaps, by using large panes, and inserting them in wooden grooves, rendered water-tight by a sparing use of putty. Again, in plain lean-to or shed roofs, the morning and evening sun presents its direct rays at a low angle, and consequently very obliquely to the glass. At those periods, most of the rays of light and heat are obstructed by the position of the glass and heavy rafters; it therefore became evident that, by placing the glass more at right angles to the morning and evening rays of the sun, would be removed the obstructions to rays of light entering the house at an early and late hour of the day. This led to the adoption of "the ridge and furrow" principle for glass roofs, which so places the glass that the rays of light in mornings and evenings enter the house without obstruction, and present themselves more perpendicular to the glass when they are the least powerful; whereas at mid-day, when they are most powerful, they present themselves more obliquely to the glass. Upon this principle Mr. Paxton constructed a pine-house in 1833, as an experiment, which continues in successful use to this day. It next became a question of importance how far an extensive structure might be covered in with flat ridge and furrow roofs, that is, the ridge-and-valley rafters placed on a level, instead of at an inclination. Several buildings, embracing more or less of this design, were accordingly constructed by Mr. Paxton, but it was not until 1848 that the plan was fully carried out in the erection of a conservatory for the reception of the gigantic water-lily of South America, the Victoria Regia. This building was 60 feet in length by 46 in breadth, and, although a diminutive structure when compared with the Exhibition building, yet the principles upon which it was constructed are the same, and may be carried out to an unlimited extent. The lily house, however, was so built as to retain as much heat and moisture as possible, and yet to afford a strong and bright light at all seasons; whilst, on the contrary, the Industrial Building, being intended to accommodate a daily assemblage of many

thousands of individuals, and a vast number of natural and mechanical productions, many of which would be destroyed by moisture and heat, is constructed so as fully to answer that end. A sort of twofold econ

omy characterizes the entire building: the walls and foundations are, at the same time, drains and ventilators; the roofs, besides being the most extensive of known skylights, are light-and-heat adjusters; the sash-bars not only hold the glass together, but are self-supporting; and the rafters form perfect drains for both sides of the glass, for draining off internal as well as external moisture; whilst the tops of the girders are conduits also; and the floors are dust-traps and aid in ventilation. Paxton's Plan for the Exhibition Building. The peculiar structure of the leaves of the gigantic water-lily suggested, in some measure, to Mr. Paxton, the principle on which the Exhibition building was afterwards constructed. In a lecture delivered to the Society of Arts upon the details of his design for the Great Exhibition building, he exhibited a specimen of the leaf, five feet in diameter, of only five days' growth; and to prove that not only the house for the flower, but the flower itself, has a striking relation to the Palace of Glass, Mr. Paxton remarked: "The under side of the leaf presents a beautiful example of natural engineering in the cantilevers, which radiate from the centre, where they are nearly two inches deep, with large bottom flanges, and very thin middle ribs, between each pair of which are cross-girders, to keep the ribs from buckling; their depth gradually decreasing towards the circumference of the leaf, where they also ramify." Upon this "natural engineering," Mr. Paxton assured us that he first devised the self-supporting principle, which he has applied in the roof of the Great Building.

The Lily-house was scarcely completed, when the clamorous objections raised to the brick-and-mortar design of the Building Committee first led Mr. Paxton to consider the practicability of applying his novel plan to the construction of a vast Exhibition House; but the circumstance of the Building Committee having invited tenders for the construction of their design was supposed to shut out fresh competitors. The fact proved otherwise. Leave was granted to Mr. Paxton to bring in his plan, which he undertook to complete in nine days. This was on the 14th of June; other business intervened, and it was not until the 18th of June that Mr. Paxton, while presiding at a railroad meeting, first sketched the outline of the proposed building on a sheet of blotting paper. The plans and specifications were, however, completed by the 28th of June, and submitted. After some delay, and various objections, the committee abandoned their own design, and contracted with Messrs. Fox and Henderson to construct Mr. Paxton's building for the sum of £79,800. To this design was added a transept, crossing nearly at its centre, so as to avoid the removal of the largest and loftiest trees within the area. The contractors bound themselves, for a certain sum of money, and in the course of some four months, to cover eighteen acres of ground with a building upwards of a third of a mile long, (1848 feet,) and some 408 feet broad. In order to do this, the glass-workers promised to supply, in the required time, nine hundred thousand square feet of glass (weighing more than 400 tons,) in separate panes, and

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 guttering 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 undertook 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.

Details 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 external 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 gutters, 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 of an inch to 1 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 standards interposed between their upper and lower flanges, which divide the rectangular space into three open frames, each of which is intersected 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 building 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 connecting 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, corresponding 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

and screw. The second tier of columns was then fixed in precisely the same manner on the connecting pieces; and thus were securely joined the girders throughout the building. The peculiar action of the connecting pieces, however, should be further explained. The projections, or snugs, upon their upper and lower portions, act not only as brackets, but likewise hooks; those on the lower ends bending upwards, and those on the upper ends downwards, so as between them to grasp the end struts or standards of the girder. To retain the girder in a vertical position, and prevent any lateral movement, its bottom and face have a tenon, which drops into a mortice-hole in the projection of the connecting piece; while the top end face of the girder, over which the upper connecting piece hook extends, is grooved to correspond with the projection, and the two surfaces are keyed together by a piece of iron. This system of attaching the girders to the projections of the connecting pieces has proved very successful. The principle of the ridge and valley roof, as applied by Mr. Paxton to horticultural buildings, was well adapted from its extreme lightness to buildings of great extent, the whole roof of the exhibition building weighing only upon an average 31 lbs. per superficial foot. This was the result of the subdivision of surface in the light frame-work and rafters. From a roof of such light construction it became important to convey away the rain-water as soon as possible; for it is estimated that were a quantity of water, one-eighth of an inch in depth, suffered to remain upon the roof, an additional pressure of 275 tons, for the time being, would be the consequence. This is prevented by means of cambered or curved beams of wood, which divide the roof into spaces of eight feet each, and are the gutters into which the water runs from off the glass roofs, which slope into them on either side. These cambered gutters run longitudinally, and their entire length is no less than 34 miles. These lines of gutter were made in 24-feet lengths, each cambered upwards, so that the water in the gutter has only to run down one-half its extent, and thus off the roof at one end of the furrow, where it discharges itself through a casting into a second and larger gutter lying transversely to the first, and resting upon the roof girders. The fall of the smaller gutter on either side is 24 inches in 12 feet, or 1 inch in 4 feet 9 inches; so that the water is at once drained into the larger gutter, and thus conveyed to the hollow columns before it can accumulate at any one point throughout the building. Not only is the roof drained externally in the manner described, but small channels are provided in the longitudinal gutters to carry off the condensed vapor from the interior surface of the roof.

The glazing of this vast roof was executed in the following manner. The sash-bars, having been painted, were received upon the roof, where both their grooves were filled with putty, as was also the rabbet in the ridge, and the sill in the furrow; the side edges of the pane were then inserted in the bar grooves, and the glass thus framed at the sides was laid in its place, prised up by the workmen into the ridge, and fastened at the lower end by a nail driven into a drilled hole in the bar; but the larger sash-bars were fastened into the ridge by dowels. As the glazing required to be executed in a very short time, "glazing-wagons