effect was secured by the mere repetition of a column and a girder which, although striking and simple, was certainly monotonous ; and, moreover, in consequence of the great length of the building, the columns and girders succeeded one another so rapidly that the eye had no means of measuring the actual length. At Sydenham pairs of columns and girders are advanced eight feet into the nave at every seventy-two feet, thus breaking the uniform straight line, and enabling the eye to measure and appreciate the distance.

The building above the level of the floor is entirely of iron and glass, with the exception of a portion at the north front, which is panelled with wood. The whole length of the main building is 1608 feet, and the wings 574 feet each, making a length of 2756 feet, which with the 720 feet in the colonnade, leading from the railway station to the wings, gives a total length of 3476 feet; or nearly three-quarters of a mile of ground covered with a transparent roof of glass. The length of the Hyde Park building was 1848 feet, so that, including the wings and colonnade, the present structure is larger than its predecessor by 1628 feet; the area of the ground floor, including the wings, amounts to the astonishing quantity of 598,396 superficial feet; and the area of gallery flooring of building and wings to 245,260 superficial feet, altogether 843,656 superficial feet. In cubic contents the Palace at Sydenham exceeds its predecessor by nearly one-half. The width of the nave, or main avenue, is 72 feet, which is also the width of the north and south transepts; and the height of all three from the floor to the springing or base of the arch, is 68 feet; the height from the flooring to the crown or top of the arch being 104 feet, just the height of the transept at the old building. The length of the north and south transepts, is 336 feet respectively. The length of the central transept is 384 feet; its width 120 feet; its height from the floor to the top of the louvre, or ventilator, 168 feet; from the floor to the springing of the arch, 108 feet; and from the garden front to the top of the louvre, 208 feet, or 6 feet higher than the Monument.

The floor consists of boarding one inch and a half thick, laid as in the old building, with half-inch openings between them, and resting on joists, placed two feet apart, seven inches by two and a half inches thick. These joists are carried on sleepers and props eight feet apart. The girders which support the galleries and the roofwork, and carry the brick arches over the basement floor, are of cast-iron, and are 24 feet in length. The connexions between the girders and columns are applied in the same manner as in the building of 1851. The principle of connexion was originally condemned

by some men of standing in the scientific world; but experience has proved it to be sound and admirable in every respect. The mode of connexion is not merely that of resting the girders on the columns in order to support the roofs and galleries, but the top and bottom of each girder are firmly secured to each of the columns, so that the girder preserves the perpendicularity of the column, and secures lateral stiffness to the entire edifice. Throughout the building the visitor will notice, at certain intervals, diagonally placed, rods connected at the crossing, and uniting column with column. These are the diagonal bracings, or the rods provided to resist the action of the wind: they are strong enough to bear any strain that can be brought to bear against them, and are fitted with screwed connexions and couplings, so that they can be adjusted with the greatest accuracy. The roof, from end to end, is on the Paxton ridge-and-furrow system, and the glass employed in the roof is of an inch in thickness (21 oz. per foot). The discharge of the rain-water is effected by gutters, from which the water is conveyed down the inside of the columns, at the base of which are the necessary outlets leading to the main-drains of the building. The first gallery is gained from the ground-floor by means of a flight of stairs about 23 feet high; eight such flights being distributed over the building. This gallery is 24 feet wide, and devoted to the exhibition of articles of industry. The upper gallery is 8 feet wide, extending, like the other, round the building; it is gained from the lower gallery, by spiral staircases, of which there are ten : each stair-case being divided into two flights, and each flight being 20 feet high. Round this upper gallery, at the very summit of the nave and transepts, as well as round the ground floor of the building, are placed louvres, or ventilators, made of galvanized iron. By the opening or closing of these louvres-a service readily performed the temperature of the Crystal Palace is so regulated that on the hottest day of summer, the dry parching heat mounts to the roof to be dismissed, whilst a pure and invigorating supply is introduced at the floor in its place, giving new life to the thirsty plant and fresh vigour to man. The coolness thus obtained within the palace will be sought in vain on such a summer's day outside the edifice.

The total length of columns employed in the construction of the main buildings and wings would extend, if laid in a straight line, to a distance of sixteen miles and a quarter. The total weight of iron used in the main building and wings amounts to 9,641 tons, 17 cwts., 1 quarter. The superficial quantity of glass used is 25

acres; and, if the panes were laid side by side, they would extend to a distance of 48 miles; if end to end, to the almost incredible length of 242 miles. To complete our statistics, we have further to add that the quantity of bolts and rivets distributed over the main structure and wings weighs 175 tons, 1 cwt., 1 quarter ; that the nails hammered into the Palace increase its weight by 103 tons, 6 cwt., and that the amount of brick-work in the main building and wings is 15391 cubic yards.

From the end of the south wing to the Crystal Palace Railwaystation, as above indicated, is a colonnade 720 feet long, 17 feet wide, and 18 feet high. It possesses a superficial area of 15,500 feet, and the quantity of iron employed in this covered passage is 60 tons; of glass 30,000 superficial feet.

HOT-WATER APPARATUS.

Vast as are the proportions of the Crystal Palace, novel and scientific as is the principle of construction, we are in some degree prepared for this magnificent result of intellect and industry by the Great Exhibition of 1851. One arrangement, however, in the present structure, admits of no comparison; for, in point of extent, it leaves all former efforts in the same direction far behind, and stands by itself unrivalled. We refer to the process of warming the atmosphere in the enormous Glass Palace to the mild and genial heat of Madeira, throughout our cold and damp English winter.

The employment of hot water as a medium for heating apartments, seems to have been first hinted at in the year 1594, by Sir Hugh Platt, who, in a work entitled "The Jewell House of Art and Nature," published in that year, suggests the use of hot water as a safe means of drying gunpowder, and likewise recommends it for heating a plant-house. In 1716, Sir Martin Triewald of Newcastle-on-Tyne, proposed a scheme for heating a green-house by hot water; and a Frenchman, M. Bonnemain, a short time afterwards invented an apparatus for hatching chickens by the same means. In the early part of this century Sir Martin Triewald's plan of heating was applied to conservatories, at St. Petersburgh; and a few years later, Bonnemain's arrangement was introduced into England, where it has undergone several improvements, and occupied the attention of scientific men. Its application to the heating of churches, public libraries, and other buildings, has been attended with considerable success, and

it is now looked upon as the safest, as well as one of the most effectual artificial methods of heating.

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The simple plan of heating by hot water is that which Sir Joseph Paxton has adopted for the Crystal Palace. But simple as the method undoubtedly is, its adaptation to the purposes of the Palace has cost infinite labour and anxious consideration for hitherto it has remained an unsolved problem how far, and in what quantity, water could be made to travel through pipes-flowing and returning by means of the propulsion of heat from the boilers. At Chatsworth, the seat of the Duke of Devonshire, the principle has been carried out on a large scale, and the experiment there tried has yielded data and proof: but in the present building, a greater extent of piping has been attached to the boilers than was ever before known, or even contemplated. In order to give the visitor some idea of the magnitude of the operation in question, it will be sufficient to state that the pipes for the conveyance of the hot water, laid under the floor of the main building, and around the wings, would, if placed in a straight line, and taken at an average circumference of 12 inches, stretch to a distance of more than 50 miles, and that the water in flowing from and returning to the boilers, travels one mile and three-quarters. But even with these extraordinary results obtained, the question as to the distance to which water can be propelled by means of heat, is far from being definitely settled. Indeed, Sir Joseph Paxton and Mr. Henderson have invented an ingenious contrivance, by means of which, should it ever be required, a much larger heating surface may be called forth at any time in any particular portion of the building.

The general arrangement of the Heating Apparatus may be described as follows:-Nearly twenty-four feet below the surface of the flooring of the main building, and leading out of "Sir Joseph Paxton's tunnel "* (the name given to the roadway in the

*The formation of tunnels, for the passage of water especially, and for drainage, was well known to the ancient Greeks and Romans, and the remains of many of their great works of this kind possess an extreme interest. In the tunnel or underground canal of the Abruzzi in Italy, formed by the Roman Emperor Claudius, and lately cleared out by the Neapolitan Government, nearly the same means appear to have been used for its excavation and construction as are employed in forming tunnels at the present day. Amongst other remarkable tunnels of antiquity may be cited that of Posilipo at Naples, nearly three-quarters of a mile long, probably constructed about the time of Tiberius (circa A.D. 30), and the Greek tunnel, 4200 Greek feet in length, excavated through a mountain for the purpose of conveying water to the city of Samos. One of the earliest tunnels of modern times was made at Languedoc in

basement story, extending the whole length of the building on the side nearest the Gardens), are placed, at certain intervals, boilerhouses, each containing two boilers capable of holding 11,000 gallons of water. The boilers are twenty-two in number, and are set in pairs. In addition to these, a boiler is placed at the north end of the building, on account of the increased heat there required for the tropical plants. There are also two boilers set in the lower stories of each wing, and two small boilers are appropriated to the water in the fountain basins at each end of the building, which contain Victoria Regias and other aquatic plants of tropical climes. Four pipes are immediately connected with each boiler; two of such pipes convey the water from the boiler, and the other two bring it back; they are called the main pipes, and are nine inches in diameter.

Of the two pipes that convey the water from the boiler, one crosses the building transversely-from the garden-front to the opposite side. Connected with this pipe, at certain distances, and in allotted numbers, are smaller pipes, five inches in diameter, laid horizontally, and immediately beneath the flooring of the building. These convey the water from the main pipe to certain required distances, and then bring it back to the return main pipe, through which it flows into the boiler. The second main pipe conveys the water for heating the front of the building next to the Garden; and connected with this, as with the other main pipe, are smaller pipes through which the water ramifies, and then, in like manner, is returned to the boiler. Thus, then, by the mere propulsion of heat, a vast quantity of water is kept in constant motion throughout the Palace, continually flowing and returning, and giving out warmth that makes its way upwards, and disseminates a genial atmosphere in every part.

To ensure pure circulation throughout the winter, ventilators have been introduced direct from the main building into each furnace, where the air, so brought, being consumed by the fire, the atmosphere in the Palace is continually renewed.

THE ARTESIAN WELL, AND THE SUPPLY OF THE FOUNTAINS.

In July, 1852, the supply of water for the fountains and other great works in connexion with the Crystal Palace, first seriously

France, A.D. 1666: since that period they have become general. The great labour required in their formation, is likely to be obviated by the invention of a machine by an American, which is said to be capable of cutting a rapid way even through masses of rock.