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PLAN OF CLERKSTORT.

Char. IV.
PRINCIPLES OF PROPORTION.

1061 nave, we have three perfect cubes of 24 feet in each severy up to the bottom of the trifa rium story, and the same number from thence to the top of the vaulting of the navc.

The main pillars are 7 feet, and 7 feet 2 inches in diameter, composed of a large cylindrical column, with others attached for the support of the vaulting. Towards the nave there are three columns which are carried up to the height of about the middle of that of the clerestory windows; on the capi. tals which terminate them rest the cross springers and diagonal ribs of the vaulting. The arches of each division are 4 feet 9 inches in thick. ness, and rest on the side columns, of

Fig. 1329. 18 inches diameter. The faint line on the plan fig. 1329. represents the pier and mullions of the division of the clerestory window.

1.6 The seven circles shown in fig. 1328. exhibit the proportion each pier bears to the opening, namely, that of twosevenths for piers, and five-serenths for the space between them.

The dimensions vary a little as taken throughout the six severies, as in some instances the diameter of the piers varies as above stated.

It may be remarked that the contour of the torus and scotia in the base, are not sections of cylinders or their portions, but partakes of the elliptical. The mouldings below, are contoured differently to those above, the eye, and consideration is given to their position, Fig. 1550. to produce proper effect.

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PLAN OF COLUMNS; AMIEXS.

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The base and capital of the main pillars, as here shown with their dimensions, is the same as the front view towards the nave, with the exception that the two 7-inch columns at the side of that in the middle are omitted.

The piers that divide the side chapels, and the original outer buttresses, have been changed probably from their original design; they are now 8 fvet wide

.2'6".

The clerestory window with its piers and mullions being already given (fig. 1329.) ir remains to show the plan of the piers and mullions of the triforium, and its gallery or passage, which has a clear width of 20 inches between the main pier and the outer wall, which is about 10 inches in thickness (fig. 1334.) The middle mullion, or that which divides the triforium into two principal arches, is 2 feet 6 inches in width, and composed of seven sırall columns, as shown attached to the main pillar, which has a depth of 6 feet 8 inches.

The ordinary decoration in this ca. thedral is very simple, consisting of a circle, comprising either three, four, five, six, or eight others ; the centres of which and their portions may be understood by reference to the five diagrams figs. 1335. to 1339. Sculptured foliage ocours in the capitals and along the string inouldings; figures, however, of the most elaborate execution and design decorate the exterior, and particularly around the chief entrances; perhaps few buildings excel the Cathedral of Amiens in the richness of these portions, or the magnificence of its porches. In describing the figs. 1292. and 1294., an attempt was made to convey an idea of the geometrical style of the tracery in the rose windows, as well as those of the side chapels,

We cannot quit this part of our subject without regretting the want of further space for the treatment of this very interesting reference to the arts as displayed by the builders of this period, particularly as the principles upon which they practised are so little known. Simple as they were, their system seems to have been forgotten after the lodges of the freemasons were broken up, and the new era appeared. The renaissance, or the return to the Greek models, at once set aside all knowledge of that architecture which bad attained such perfection in Europe for four centuries.

Fig. 1334.

PLAX OY TRIYORUM.

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Fig. 1538.

Fig. 1339. THE BUILDING FOR THE EXHIBITION OF THE INDUSTRY OF ALL NATIONS, 1851. This building was stated to have been suggested to the Society of Arts in June 1845 by his Royal Highness Prince Albert, and it was not long ere the plan for its adoption was developed. The public quickly responded to an appeal by subscribing 75,0001. to enable the commissioners to erect a suitable building, to be completed by the 1st of May 1851; the site being granted by Her Majesty, on the south side of Hyde Park ; and all Chat was required of the exhibitors was, to deliver their various specimens of art and

manufacture at the building which would be provided for them. Mr. Paxton, after some other designs had been set aside, submitted a design composed chiefly of glass and iron, which Messrs. Fox, Henderson, & Co. tendered to construct for 79,8001. This was immediately carried into effect.

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TUE BUILDING FOR THE EXHIBITION OF ALL NATIONS, 1851, COMOXONLY CALLED THE CRYSTAL PALACL

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The site for the building contained about 26 acres, being 2,300 feet in length, and 500 feet in breadth; the principal front extending from west to east. The total area of the ground-floor was 772,784 superficial feet, and that of the galleries 217,100 square feet. The length of these galleries extended nearly a mile. The cubical contents of the building were estimated at 33,000,000 feet.

There were used in its construction 2,300 cast iron girders, 358 wrought iron trusses iur supporting the galleries and roof, 30 miles of gutters for carrying water to the columns which served as water-pipes, 202 miles of sash-bars, and 900,000 superficial feet of glass.

On the ground-floor, 1,106 columns of cast iron, rested on cast iron plates, based upon concrete ; these columns were 8 inches in diameter, and 18 feet 54 inches in height; they were cast hollow, the thickness of the metal varying from to 1} in., according to the weights they were destined to support. The sectional area was increased by four broad fillets or faces, 3} inches in width, and a little more than a sixth of an inch in thickness.

The principal entrance was in the centre of the south side ; passing through a vestibule 72 feet by 48, the transept was entered, which was covered by a semi-cylindrical vault 72 feet in diameter, springing from a height of 68 feet from the foor; and this vault of iron and glass was in length 408 feet from north to south. On each side of the transept was an aisle 24 feet wide.

Standing in the middle of the transept, the vista or nave, at right angles, extended easi and west 900 feet in each direction; the total length being 1,848 feet. This nave was 72 feet wide, and 64 feet high ; and on each side was an aisle 24 feet in width ; and above, at a height of 24 feet from the floor, were galleries which surrounded the whole of the nave and transept.

Beyond these side aisles and parallel with them, at a distance of 48 feet, were second side aisles, of an equal width to those already mentioned, and also covered with galleries on a similar level to the others. Bridges of communication were made at convenient distances, to allow of an unbroken promenade, and from which a view of the several courts might be obtained. These courts were roofed in, at the height of 2 stories, and were 48 feet in width. Ten double staircases 8 feet wide gave access to the several galleries.

After the transept and nave were marked out, the general arrangement consisted of a series of compartments 24 feet square, and as much in height; these bays or cubes were each formed of 4 columns, supporting girders put together very ingeniously. One of these bays or gallery-floors, 24 feet square, containing 576 superficial feet, was calculated to support as many cwts., or 30 tons.

The symmetry and strength of this vast building depended upon the accuracy with which the simple plan was drawn out, and much credit is due to Mr. Brounger, who superin. tended this portion of the work. He had to establish a series of squares of 24 feet, and this was admirably effected by rods of well-seasoned pine, fitted with gun-metal cheeks.

Stakes were driven into the ground to mark the position of the columns, their precise centres being afterwards found by the theodolite, and marked by a nail on the top of the stake or pile; and when the digging commenced for the foundations, and there was a necessity to move the pile, a right-angled triangle was formed in deal, and previous to the removal of a stake, a nail indicating the position of the column was placed at the apex of the triangle; two other stakes were driven in, and the first withdrawn. The entire ground plan may be considered as composed of 1,453 squares, each containing 576 superficial feet. The south front occupied 77, the east and west fronts each 17, so that the entire parallelogram contained 1,309 of these squares; on the north side were 48 others, 3 divisions in depth, making an additional 144, thus completing the number stated. The nave, transept, and courts were formed by the omission of the columns, where their width required to be either 48 or 72 feet, and girders of sufficient strength were substituted to span the space where such columns were omitted. Had each of the 1,387 squares of which the plan consists had its compleinent of columns to have perfected each cube, 1,502 would have been required; but the formation of the wider openings occasioned only 1,106 to be employed, so that, by the omission of a third, the courts, nave, and transepts acquired their admired proportions. Each of the 1,387 squares was 576 superficial feet, or a total of 798,912 superficial feet. The columns being 8 inches in diameter, the area of the section of the whole 1,106 was 380 superficial feet, or the points of support were a trifle more than a 2,000th of the entire area, for 2012 - 2,102.

When we compare the Crystal Palace with one of the lightest constructed basilicas of ancient Rome, we are astonished at the difference in the proportions. For instance, the total area of the basilica of St. Paul without the walls of Rome, was 108,000 superficial teet ; while the points of support were 12,000, or one ninth. The Crystal Palace, which was seven times the area of the basilica of St. Paul, had it been constructed in a similar manner, would have required 84,000 superficial feet for the points of support, instead of 380 superficial feet.

In the Saxon cathedrals, one third of the entire area was employed for walls and piers; in the Pantheon at Rome, one quarter ; in St. Paul's, London, one sixth ; and in most of the cathedrals constructed from the 12th to the 15th century, the same proportions are practised; but we have never hitherto seen any attempt to lessen the proportions of the supports beyond a twentieth of the entire area, when the ordinary building materials, as brick or stone, have been employed, whilst in this instance iron columns are found sufficiently strong, when they have the proportion of a 2,000th part of the whole, or are one hundred times less in section than their points of support, estimated as a twentieth of the whole, and which we have considered as the lightest of the constructions hitherto practised; the round Temple of Claudius at Rome being the example. Tredgold calculated that an iron column of cast iron 8 inches in diameter, and 24 feet higli, will carry nearly 50 tons, or 1,106, 55,300 tons; so that, if each of 1,387 squares had to sustain 30 tons, there would be ample strength, this not amounting to more than 41,610 tons.

In preparing the foundations for the columns, great care was taken to arrive at the gravel, upon which a bed of concrete was thrown ; and it was estimated that a pressure per superficial foot of 2 tons should be provided for. The concrete varied in depth from 3 to 4 feet, and was finished by covering the top with a surface of fine mortar, worked even and with a level face. On this was laid a base plate for each column, the lower part consisting of a horizontal plate having attached to it a vertical tube of the form of the column it was to carry. The length of these base plates was from north to south, so that the water brought down by the columns from the roof might run in the direction from east to west. Into the sockets, cast iron pipes 6 inches in diameter were inserted, for the purpose of conveying the water into the cisterns and tanks provided to receive it.

At the upper portion of the base plate four holes were cast, in as many projections, which answered to others at the foot of the column to be placed upon it, which, when fixed, was secured by nuts. Between the shaft and its base, pieces of canvas dipped in white lead were introduced before the joints were secured, which were thus rendered water. tight. The columns were 8 inches in diameter, and those on the ground floor 18 feet 5 inches in height, being cast hollow to allow of a current for the rain water ; the strength of these columns was increased by four projecting ribs, and by the form of angular additions made to receive the nuts and screws. The Crystal Palace at Sydenham had also the simple cube as the nucleus of which this vast

edifice was composed; and the simplicity of its form enabled the constructors, by a small variety of castings, to execute the whole. It was to this locality that the materials of the Hyde Park building were removed and readapted to a much

extensive erection, Three cubes, placed one on the other, formed the side galleries, as seen in the section, fig. 1342 The omission of six such cubes ineasures the width and height of the nave to the level of the springing of the arched covering; such are the sim. ple proportions composing this vast structure. On the ground-floor is laid board

ing 1; inches in thickness, Fig. 1342.

an inch apart, upon joists 7 inches by 2 inches, which rest upon sleepers 13 inches by 31 inches, placed 8 feet apart. The second tier of columns are 16 feet 7 inches long, with connecting pieces 3 feet 4 inches deep, and a similar girder to those below. The third tier of columns and connecting pieces in every case are the same as the second.

SPRINGING

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SECTION OF THE CRISTAL PALACE, SYDENHAX.

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