CHAPTEE XII 
DEFECTS IN TIMBER AND GENERAL NOTES 
Heartshakes— Eingshakes— Knots — Grain — Sap — Wnny Timber— 
Toughness— Flexibility— Microscopical Sections of Wood- 
Resonance— 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 rmi 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 
