SUPERSTRUCTQEES. Ill 



4. Cloven Timber. 



Cloven timber comprises all those sorts of timber in which the 

 wood is split, or cloven, along the direction of the fibres ; it com- 

 prises staves for casks, park-palings, laths, shingles for roofing, 

 spokes for wheels, rungs for ladders, hurdle-wood, &c. This 

 class of wood is characterised by the fact that the fibres not being 

 severed, the wood preserves its natural elasticity and strength, 

 and is much less permeable by liquids, and less liable to warp 

 and crack than sawn timber. The work of cleaving timber is 

 also more expeditious, and requires simpler implements than 

 sawing, and there is scarcely any waste of material involved. 



In cleaving wood, it is advisable, whenever possible, to work 

 from the centre of the piece of wood outwards. 



Section II. — Timber used in Superstructures. 



(a) Different Kinds of Superstructure. — The term superstruc- 

 ture includes all parts of buildings which are above ground or 

 water, so that the timber used in their construction may be 

 exposed to the external air and to atmospheric influences, but 

 not to moisture from the soil or in water-courses. Building- 

 timber may be distinguished into sawn timber (beams, planks 

 and scantlings), which is fitted by a carpenter, and planed 

 timber used for floors, doors and windows, and fitted by a 

 joiner. 



According to the demands on the durability, strength, beauty, 

 cVc. of the timber used, and to its local value, different modes of 

 building are employed, some of which use timber in lar^e 

 quantities, and others much more sparingly. 



These modes of building may be distinguished by the nature 

 of the walls erected. Thus, block-houses, or log-huts, have 

 entirely wooden walls ; the wooden framework sometimes em- 

 ployed for the walls of houses may be filled-in with planks, 

 bricks, or lath and plaster ; the walls of other superstructures 

 are built of mud, stone, or brick masonry. 



In the case of log-huts, the walls of the whole building are 

 made of round logs or squared balks, the necessary firmness of 

 the building being secured by dovetailing their ends into beams 



