ROOT ( no ) 



brought on the market. It is an ever expanding line of 

 business, one largely supplied in the twentieth century by 

 Canadian birch. In instances where one of a pair is hard- 

 wood " lignum vitae " is used. See "Wringing Machine 

 Rollers." 



Roller Bearings. Bearings in which steel rollers are used to 

 reduce the friction. In some cases the rollers are hollow, 

 but the best types have short rollers of hardened steel, 

 accurately ground to size and running between two hardened 

 steel concentric rings. 



Roller-feed Benches. Circular saw benches fitted with power 

 rollers to grip the wood being operated upon and force it 

 to the saw. They have largely replaced the earlier " rope- 

 feed benches." 



Rolling Machine for Band Saws. A machine in which the saws 

 are squeezed between hardened steel rollers, so as to expand 

 the steel in the centre, and to put into the saw what is 

 known as tension. 



Rood-beam. A horizontal beam, usually the capping of a church- 

 screen, on which the holy-rood is fixed, where a stage or 

 gallery is formed at its level. The term is merged into 

 " rood-loft," of which it forms part. 



Roof. In architecture, the cover of a building, irrespective of 

 the material of which it is composed. The forms are numer- 

 ous : amongst them are house, barn, shed, gable, hip, conical, 

 ogee, curb, wagon, pent-house (ivhich see), span, saddle, 

 hammer-beam (which see), also mansard (which see) and 

 ' Pitch (of a Roof)." 



Roof-tile. Roof covering of earthenware tiles varied in form, 

 ; 'flat" or "concave," and in colour "buff," "red" or 

 " black," " glazed " or otherwise. A mixed colour is termed 

 " brindled." See "Tile." 



Roof-timbers.- Consist of the main and minor parts ; the former 

 being " the principals," each of which, as frames, is called 

 "a pair." The most common is the "king-post" form, 

 with one central post ; the less common and usually the 

 largest span is the " queen-post " form, with two posts and 

 " a loft " or space between. 



Roof-timber Terms. Tie-beam, hammer-beam, king-post, queen- 

 post, principal rafters, braces or struts, ridge piece, tree or 

 board, purlins, collar beams or collars, common rafters, pole 

 plates, wall plates, hammer brace, side-post, straining- 

 beam, etc. See " Hammer-beam," " Collar-beam," " Bang- 

 post," " Queen-post," " Principals," " Struts," " Ridge- 

 piece," " Purlin," " Common Rafter," " Pole Plate," 

 "Roof" and "Roof Timbers." 



