BUILDING OF SHIPS AND BOATS. 



581 



to extend any further, the decision of the admissibility of the 

 affected wood must be left to an expert. Large heart-shakes, 

 frost-cracks, twisted fibre, deep-going black and brown marks 

 rotten places descending from branches, are defects, which 

 naturally exclude the timber possessing them from use in 

 shipbuilding. 



4. Shape and Dimensions. 



All shipbuilding timber is either wood for construction, or 

 for masts or spars. 



(a) Timber used in Construction. This comprises curved 

 and long wood. 



Curved or compass timber is used chiefly in the framework 



''I. I'liiformly curved piece. 





/met. 

 Fig. 332. Knee-piece. 



Fig. 331. Curvature one 

 third from end. 



of ships. As a rule, the curvature should be uniform through- 

 out the piece (Fig. 330), or greatest at one-third from one of its 

 ends, and when this is one-third the distance from its larger 

 end (Fig. 331), the piece is most valuable. Some of these 



