414 



EXHIBITION, BKITISH INDUSTRIAL. 





in the centre, in which latter is the main en- 

 trance to the Picture Galleries ; being about as 

 long as the gallery of the Louvre, in Paris. 

 The exterior is chiefly brickwork, relieved with 

 semicircular-headed panels, separated by pilas- 

 ters, and between the arches are circular niches ; 

 in the lower portion of each panel being a win- 

 dow, to admit light and air to the ground floor, 

 and to ventilate the Picture Galiery above. 

 The panels are plastered in cement, and it is 

 proposed to ornament them with English mo- 

 saics, dependent on the funds. The East and 

 West Fronts, though differing from the South, 

 are not less imposing. They are, in all respects, 

 similar to each other in their general aspect. 

 Here the huge domes, rising to a height* of 260 

 feet, show to most advantage, and the transept 



roof, with its lofty clerestory windows, is in 

 full view. To the observer below, the form of 

 each dome appears nearly that of a semicircle ; 

 this effect is obtained by making its height 11 

 feet more than its semi-diameter, which fully 

 allows for the loss by prospective diminu- 

 tion. 



From the crown of each dome rises the pin- 

 nacle to the height of 55 feet. Each dome is 

 in the middle of each facade ; its centre is the 

 point formed by the intersection of the centre 

 lines of the nave and transept, and the front 

 of the building is advanced from it 108 feet. 

 Under each noble arched recess is the main 

 entrance to the Industrial Courts, the effect of 

 which forms one of the most pleasing exterior 

 parts of the building. 



Each of the porches contains a deep semi- 

 circular arched recess, 68 feet span and 80 feet 

 high, in the tympan of which is the great rose- 

 window, visible from end to end within. The 

 window is one closing the vista as the spectator 

 looks from a standing point beneath the other. 



At the extreme north and south are two 

 auxiliary picture galleries, each 247 feet long. 

 The main and auxiliary picture galleries afford 

 available wall space covered by pictures, equal 

 to 7,600 square yards, or about one and a half 

 acres. 



The two duodecagonal domes are of glass, 

 with an outer and inner gallery, 160 feet in 

 diameter, and 250 feet high.* The dome of the 

 Pantheon is 142 feet in diameter and 70 feet 

 high ; the dome in the Baths of Caracalla was 

 111 feet; Brunelleschi's, at Florence, is 139 

 feet in diameter and 133 feet high ; the dome 

 of St. Peter's is 158 feet in diameter, and 263 

 feet high from the external plinth ; the dome 

 of St. Paul's Cathedral is 112 feet in diameter, 

 and 215 feet high. 



The Annexes are engineering works of great 

 merit. 



The western Annexe is 975 feet long, and 200 

 feet and 150 feet wide. The east side is en- 

 closed by the back wall of the west arcade of 

 the Gardens, and the west side, which adjoins 

 the road, has a plain lath-and-plaster front. 

 It is covered by a ridge-and-valley roof, sup- 



* The dome of the old Ilallc au B16, at Paris, of timber, 

 was 200 feet diameter; and after its destruction by fire was 

 replaced by the wrought iron and zinc dome, still in exis- 

 tence, of the same dimensions. 



ported on light wooden ribs, similar in con- 

 struction to those of the nave ; that is, they are 

 formed of planks nailed together. The circular 

 portion springs at ten feet above the ground 

 line. Its elevation is nearly half of a regular 

 polygon, described about a semicircle whose 

 diameter is 50 feet ; it consists of three planks 

 nailed together. The principal rafters, which 

 are 'composed of two f inch planks, rise from 

 a point 28 feet above the ground, and meet 

 above the curved ribs, so as to make the ridge 

 five feet above the crown of the arch. The 

 upright, which has its foot mortised into a 

 sleeper resting on piles, is formed of 1J inch 

 centre plank, with a inch plank on each side, 

 having a strengthening piece four inches by 

 three inches spiked to it on either side to pre- 

 vent its bending. The principal rafter and up- 

 right are connected with the curved rib by radial 

 pieces of lj inch plank, which are brought 

 rather below the inner line of the curve, and 

 finished off, for the sake of ornament, by a 

 spear head. The roof frames are therefore 

 merely planks nailed together, and so disposed 

 that the weight comes on their edge. One 

 half of the roof is covered with boards and 

 felt ; and the other half has a glazed skylight, 

 with louvres for ventilation throughout the 

 whole length. 



The western Annexe, is devoted to the exhi- 

 bition of machinery in motion, for which pur- 

 pose steam pipes, water pipes, and shafting are 

 led through it. Its superficial extent is about 

 four and a half acres. The entrance is through 

 the north end of the west transept, from which 



