Detail of a Truss. 97
was entrusted with the control of the work, to enroll men of the various trades from all parts of England, excepting in the fee of the Church, and to " arrest and imprison any contrariants."1
The timbers of the Hall roof are of Sussex oak, Qucrcus pcdunculata, chiefly from the King's forest or wood of Pettelwode. The assertion that chestnut was used for the timbering could only have been made by those who had either not inspected the roof at close quarters, or had been deceived by the surface colour or bloom which the timbers now exhibit, the result of a superficial surface rot.
Elevations of a principal truss, and a bay are illustrated in Figs, go and gi, together with a plan of the Hall. A general view is also given in the illustration facing this page. It is impossible, here, to give more than a brief description of this wonderful roof. To begin with, it was obviously impossible to obtain timbers of sufficient length to act as main tie-beams or principal rafters. The roof, therefore, begins with an upper triangulated framed structure, formed by the main and upper collar beams, the ridge with its bracing, the collar-post and the compound main and upper purlins, and the crown-post supporting the heavy ridge, together with the principal and common rafters down to main purlin level. This upper structure is carried on triangulated cantilevers, formed by the hammer-posts, the hammer-beams, the wall-posts with their arch-braces, the lower principal rafters and the compound wall-plate. To tie the whole roof together, the great curved rib or arch-brace is introduced, springing from the stone corbels at the feet of the wall-posts and rising to its apex at the centre of the main collar, intersecting both the hammer-beam and the hammer-post on its way.
Those who have read and understood the construction principles of the various roofs which have already been described, will see that in Westminster Hall several types have been compounded into the one. Sections of the various roof members are given here, necessarily to a minute scale. The following list of sizes and scantlings
139\ Jan. 21. Patent Rolls.
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