CHAPTER XII 



DEFECTS IN TIMBER AND GENERAL NOTES 



Heartshakes Eingshakes Knots Grain Sap Wany Timber 

 Toughness Flexibility Microscopical Sections of Wood 

 Kesonance Meaning of Durability Judging Timber. 



ALTHOUGH their defects and weak points have been 

 generally dealt with in detail under the different timbers 

 described, it may be well to describe here certain typical 

 defects in detail. 



Heartshakes are splits noticed in the ends of logs ; 



FIG. 42. Heartshake. 



FIG. 43. Starshake. 



they rarely run the full length of the logs of com- 

 merce, but sometimes, as in mahogany, teak, greenheart, 

 and other tropical woods, they are found towards the 

 centre of the log and cannot be detected until it is opened 

 out (Fig. 42). 



Sometimes these splits at the ends, which generally run 

 along the medullary rays, extend the full cross section of 

 the timber, sometimes only a short distance out from the 



