THE LIFE OF THE TREES 15 



in a forest early divest themselves of their lower branches. 

 These die for lack of sun and air, and the trunk covers 

 their stubs with layers of straight-grained wood. Such 

 timbers arc the masts of ships, telegraph poles, and the best 

 bridge timbers. Yet buried in their heart wood are the 

 roots of every twig, great or small, that started out to 

 grow when the tree was young. These knots are mostly 

 small and sound, so they do not detract from the value of 

 the lumber. It is a pleasure to work upon such a "stick 

 of timber." 



A tree that grows in the open is clothed to the ground 

 with branches, and its grain is found to be warped by 

 hundreds of knots when it reaches the sawmill. Such a 

 tree is an ornament to the landscape, but it makes inferior, 

 unreliable lumber. The carpenter and the wood chopper 

 despise it, for it ruins tools and tempers. 



Besides the natural diversion of straight grain by knots, 

 there are some abnormal forms to notice. Wood some- 

 times shows wavy grain under its bark. Certain trees 

 twist in growing, so as to throw the grain into spiral lines. 

 Cypresses and gum trees often exhibit in old stumps a 

 veering of the grain to the left for a few years, then sud- 

 denly to the right, producing a "cross grain" that defies 

 attempts to split it. 



"BirdVeye" and "curly maple" are prizes for the 

 furniture maker. Occasionally a tree of swamp or sugar 

 maple keeps alive the crowded twigs of its sapling for 

 years, and forms adventitious buds as well. These 

 dwarfed shoots persist, never getting ahead further than a 

 few inches outside the bark. Each is the centre of a wood 

 swelling on the tree bod}^ The annual layers preserve all 

 the inequalities. Dots surrounded by wavy rings are 



