RELATIONS OF WOOD TO WATER. 51 



Thus water is more mobile in broad-leaved trees than in 

 conifers, owing to the differences in the structure of their wood, 

 and especially to the position of the fibres with bordered pits. 

 The presence of resin in coniferous wood (Scotch pine and larch) 

 also causes it to retain more water when air-dried than broad- 

 leaved woods. 



(b) Extent of Surface exposed. — The rapidity of drying is 

 clearly proportional to the extent of woody surface exposed, and 

 it is clear that barked wood dries more rapidly than unbarked 

 wood. According to Koth, split and unsplit Scotch pine fire- 

 wood retain water in the ratio of 8*3 : 100, so that split wood 

 dries up 12 times faster, the surface exposed of the split wood 

 being 11 times greater than that of the unsplit. 



As planks expose more surface to the air than other forms of 

 converted timber, they dry most readily. 



(c) Humidity of the Air. — The humidity of the air varies 

 greatly, according to locality and season, and hence it is clear 

 that the effects of winter- or summer-felling on the drying of 

 timber must be considerable. Good ventilation is also very 

 important, and wood which is required to dry rapidly should 

 be placed in breezy places. Wood while drying should not 

 be in contact with the ground, from which it may absorb 

 moisture. 



(d) Mode of Seasoning Wood. — ^Yood intended for use may be 

 either dried naturally in the air, or artificially. 



Drying logs in the air is a slow process, which may take two 

 or more years. 



Wood in the round is frequently split in half or quartered, 

 or converted into planks and scantling, in order to hasten the 

 drying process ; firewood should be split. All wood intended 

 to be seasoned should be raised above the ground, to allow 

 the air to pass beneath it, and converted wood should be 

 sheltered from the rain and sun, but not so as to exclude the 

 wind. 



Timber in the round will not, a year after felling, have lost 

 much moisture as compared with its green state, and only after 

 three or four years can it be considered seasoned. Floated 

 timber, when landed and exposed on all sides to the air, dries 



E 2 



