Page:A history of architecture on the comparative method for the student, craftsman, and amateur.djvu/349

 ENGLISH GOTHIC. 29I giving the favourite form of the arch, as at Outwell Church. In roofs of steeper pitch the open space above the tie-beam was filled in with perpendicular strutting or carved open work, as at Outwell Church, Norfolk. A pillar or king-post and struts were often supported on .the tie-beam to strengthen the rafters, which gave a pleasing effect, as at Swardstone Church and also as shown in No. 131 a, b. This is an inversion of the use of king-post and tie-beam as adopted in modern roofs, in which the former acts as a suspending piece. A timber arch was sometimes introduced, springing from a wall-piece below the tie-beam, but as the tie-beam always intersected this the result, as seen at Morton Church, Lin- colnshire, and elsewhere, was not satisfactory. (2.) The " Trussed Rafter or Single-framed Roof," of which there are many examples, was probably chosen in order to form a space for the pointed vaults, and having once been used the superiority of its construction and appearance led to its being largely substituted for the tie-beam form. In roofs of large span each rafter had a collar stiffened by braces, which were sometimes passed through the collar, as at Lympenhoe Church, Norfolk, and sometimes stopped on the underside, as at Stowe Bardolph Church (No. 113 a). This type of roof was often boarded on its underside, forming a pentagonal ceiling ornamented with ribs and bosses, as at S. Mary, Wimbotsham, Norfolk. The timbers are halved and held together with wooden pins. As the rafters pitched on the outside of the wall a ledge was left on the inside, and to remove this hollow and unsightly appearance an upright strut was introduced, forming a triangular foot (No. 113 a). This greatly added to the stability of the roof, and is held to be the origin of the hammer-beam roof (No. 113 j). The arched form was obtained by the use of curved braces fixed to the rafters and collar, as at Solihull Church. (3.) The "Hammer-beam Roof" is, as stated, considered to be a natural evolution of the triangular framing adopted at the foot of the trussed rafter roof (No. 113 a), and consists generally of hammer-beam, struts, collars and curved braces, as shown in No. 113 d, e. h, j. The hammer-beam is merely the lengthening and thickening of the " sole-piece " at the foot of the trussed rafter (No. 113 j), the principal rafter being strutted, and the weight of the roof carried lower down the wall by means of a curved brace tenoned into the hammer-beam and wall-piece. Being thus strengthened, it forms a truss which, repeated at intervals of 10 feet or more, supports the intermediate rafters of the bay. It has been supposed by some that the hammer-beam arose from the cutting away of the tie-beam in the centre when a curved brace is used beneath the tie-beam. It is improbable