152 PROPERTIES OF WOOD. 



Navy, and Fig. 62 shows the usual dimensions of such pieces, 

 which were specially valuable. Even now curved pieces are 

 used largely in the construction of barges, and in the Forest 

 of Mormal near Le Quesnoy, in the north-west of France, 

 these curved pieces of oak are still sawn up by pit-saws in 

 the forest and not in sawmills. Knee pieces, used in barge- 

 making, are formed where a bough, or root, parts from its 

 parent stem ; they may be of oak, pine, or spruce (Fig. 63). Tr.] 



Forking of the stem is normal in isolated broadleaved 

 trees at a short distance from the ground. In trees grown 

 in dense crops it is abnormal when the fork is lower down 

 the stem than about 30 feet, as valuable long logs should 

 be over that length. Irrespective of bad silvicultural treatment, 

 soil and climate, in a word, the locality, may cause a tree 

 to fork. It is certain that trees fork most on good soil, though 

 the reason for this is unknown. If we consider individual 

 species, it is found that, in oak and beech, forking is repeated 

 at regular intervals along a tree. Every crop of broadleaved 

 trees affords examples of this, and ash is also specially liable 

 to fork, owing to loss of its terminal bud. 



Beech trees usually swell at a fork, in the angle of which 

 water collects, and this causes incipient decomposition of the 

 wood below it, that is termed Wassertopfe in German (water- 

 cup). 



Silviculture teaches us to remove forked trees in thinnings, 

 but the necessary preservation of the density of the crop often 

 prevents this from being done too radically. [It is not, therefore, 

 always advisable, owing to danger of windfall or of admitting 

 sunlight to the soil, to cut out all forked trees in thinnings. This 

 is especially the case in crops of silver-fir, where there may be 

 many cankered trees that require prior attention. Mr. Ingold, 

 inspector of forests at Ge"rardmer, remarks on the difference 

 between V and U-forked trees. When double leaders are 

 united in a V, there is much bark between the two stems, for 

 their union is being constantly raised as they grow in thick- 

 ness, while in U-shaped stems the two leaders are independent. 

 The V trees are, therefore, very liable to be split by the wind 

 or snow, while the U trees are much more resistant. The 

 former only are, therefore, removed in thinnings. 



