STAR- AND HEART-SHAKE. 



69 



the tree is newly felled as to be scarcely perceptible. In such 

 a case they generally widen during seasoning, from the more 

 rapid drying of the outer layers, their sides becoming darker in 

 colour than the rest of the wood. In other instances the clefts 

 may have extended to the circumference of the stem, in which 

 case they may have been so overgrown by new wood as to form 

 a longitudinal rib down the exterior of the bark, a sure sign of 

 the defect to the experienced timber surveyor. Such extreme 

 cases at least seem to be always the result of frost or sun, the 

 latter being specially frequent in the case of smooth thin-barked 

 species, such as Beech and Hornbeam, in which lines of the cortex 

 are killed by sun-burn. 



FIG. 40. Heart-shake. 



Heart-shake. More common than either cup-shake or star- 

 shake is heart-shake, one or two clefts crossing the central rings of 

 the stem and widening towards the centre (Fig. 40). 



This may occur in almost every kind of timber, whether coni- 

 ferous or broad-leaved, and seems to be quite independent of 

 soil or situation. Among species least affected by it Mr. Laslett 1 

 mentions the so-called African Oak or Teak (Oldfieldia africdna), 

 Sabicu, Spanish Mahogany, Common Elm, Dantzic Fir or Redwood 

 (Pinus sylvestris), Canadian Red Pine (Pinus resinosa), and, some- 

 what less free from it, Canadian Yellow Pine (Pinus Strobus) 

 1 Timber and Timber-trees, ed. ii. p. 54. 



