82 The Trunk 



is more valued. A thin shaving of wood will show you 

 very nicely the old pipes and fibres lying close together, 

 all growing in the same direction. This direction is what 

 carpenters mean when they speak of the grain of wood. 

 When they use a plane for smoothing planks they work 

 it along these fibres and never across. This is also the 

 only direction in which wood splits. 



Fig. 41. Cross section of an Oak trunk, showing dark heart wood in the 

 centre with lighter sap wood surrounding it. 



As a ring is added to the trunk every year, the older 

 a tree is the thicker it will be, and you can find out its 

 age by counting the number of rings. Not only this, 

 but, by looking at each ring you can tell by its width if 

 the weather during the year when it was added was 

 mild or severe. A warm moist year will produce a 

 thick ring, and a cold or dry year a thin one. If the 

 roots at any time happen to reach an unusually rich 



