"The sixth, SOME STRIKING FEATURE TO EXEMPLIFY THE PRESENT STATE OF THE SCIENCE OF CONSTRUCTION IN THIS COUNTRY. In order that the building, in which England invites the whole world to display their richest productions, may afford, at least in one point, a grandeur not incommensurate with the occasion, we propose, by a dome of light sheet iron 200 feet in diameter, to produce an effect at once striking and admirable. From calculations which have been made of the cost of so grand a Hall, we have reason to expect that it may be executed for a sum not greatly exceeding the cost of the simplest form of roof likely to be adopted to cover the same area. "It is to be borne in mind that a considerable amount of any such difference may be recovered, should this portion of the building be converted hereafter to other purposes, which is more than probable. This vast dome it is proposed to light mainly from one circle of light in its centre, and thus the sculpture will be pleasingly and suitably lit. "Six out of the eight openings in the cylinder of the dome would be well adapted for the exhibition of stained glass windows of great extent, while the two remaining arches will open to the main central gallery. The lower part of some of the voids will admit the eye to turf and shrubs, and produce a great freshness of effect. "The immense continuity of the Central Avenue will be broken and relieved by a variation in the roof opposite the openings to the second and third sets of refreshment-rooms, and windows for the reception of Stained Glass may be placed at the ends of each transverse gallery, thus terminating the vista for each. "It now only remains to explain the course of action we would recommend for adoption as soon as the principles of the plan, &c., shall be positively decided. "We consider this to be an occasion upon which the greatest amount of intellectual and commercial ingenuity and ability should be called out; and that a generous rivalry among those best fitted to execute the principal portions of this vast structure may lead to results which no amount of detailed study that we could possibly give to this matter would supply. "We would therefore recommend that every advantage should be taken of the accumulated and experimental knowledge and resources of intelligent and enterprising contractors, and that every opportunity should be afforded to them of DISTINGUISHING THEMSELVES. We would therefore recommend as the best means of enlisting their services the following course of action: "Adopting the approved design as a basis, we would proceed immediately to prepare such working-drawings and specifications as may be necessary, and to issue invitations for tenders to execute Works in accordance with them, requesting from competitors, in addition, such suggestions and modifications, accompanied with estimates of cost, as might possibly become the means of effecting a considerable reduction upon the general expense.