SELECTION OF WOOD. 79 



will seldom be durable. Oak, for instance, for building, should 

 not be less than 50 nor more than 200 years old, and Teak not 

 less than 80 years of age. 



Autumn or winter-felled wood, owing to the lower temperature, 

 splits less in drying, and for this reason, and on account of the 

 season being less favourable to fungus-growth, is more durable 

 than that felled in the spring or summer. 



Shakes, knots, especially if disposed in a ring round a stick, 

 upsets, i.e. fibres crippled by compression, or cross-grain are all 

 defects which reduce the strength of timber. Both butt and top 

 should be close, solid, and sound, any sponginess near the pith, 

 discoloration at the top, rind-gall, worm-holes, or splits produced 

 in seasoning being indications of weakness. Bright-coloured and 

 smooth-working wood is generally better than any that is dull or 

 works with a rough surface ; and heavier wood is in all respects 

 stronger than lighter wood of the same species. 



Where lightness and stiffness are desirable, coniferous wood is 

 generally preferable; and, where a steady load has to be supported, 

 the denser coniferous woods equal those of broad-leaved trees, 

 which are costlier and heavier. Where, however, moving or 

 jarring loads have to be sustained, the tougher hard woods should 

 be used. 



Conversion of timber. Split wood is straighter in grain 

 and more easily seasoned than sawn timber; and, when sawn, 

 timber will prove stronger and more durable, will season better 

 and will warp less if sawed as nearly as possible along the radii 

 of the annual rings, or, as it is termed, "quarter" or "rift" 

 sawed. This method is more expensive than tangent sawing; 

 but a little consideration will show how it secures in flooring 

 boards, for instance a more even exposure of the grain (i.e. the 

 hard bands of summer wood) on the surface. It must be borne 

 in mind that in a squared beam with the pith in its centre, whilst 

 we have some complete annual cones of wood appearing as rings 

 at the butt end and tapering to a point or to smaller rings at the 

 top, we shall also have other imperfect cones represented by rings 

 at the top but presenting tangent or " bastard " faces on the sides 



