HYciKoSCOl'K'iTY. G ( .) 



tents at the beginning and end of the drying. As regards the 

 former, sapwood contains more water at daybreak after a period 

 of rainy weather, than at sunset, after dry weather. This varia- 

 tion continues throughout the year, and is not confined to any 

 season; felling in summer or winter, therefore, alters the degree 

 of wetness of wood and the consequent shrinkage only according 

 to the weather that prevails at the time of felling. It is there- 

 fore indifferent as regards the sapwood whether wood is felled 

 in dry weather during either summer or winter. Only the 

 fact that a certain season is drier than another could render 

 it more favourable for felling trees. 



The amount of shrinkage in green wood is the greater 

 the more the wood dries ; it is greater from green wood to 

 air-dry wood than from air-dry wood to wood that is abso- 

 lutely dry. 



2. A wood that is air-dry does not, therefore, cease to warp, 

 but its volume still varies with the relative humidity of the 

 air. This fact is of great technical importance, for wooden 

 objects made in the moister climatic regions, such as the 

 British Isles, or Japan, when imported into drier countries 

 invariably warp and may become completely useless. It is 

 only when they are prevented from drying, or becoming moist, 

 under the opposite conditions of import from drier countries, 

 that they do not warp. If they are lacquered or varnished 

 they will not warp. Similar results follow for all wooden 

 objects that have been made in wet weather (window-fittings, 

 picture-frames, tables, flooring, etc.). 



3. As heartwood is always drier than sapwood, it shrinks 

 less. Heartwood of conifers contains less water than that of 

 broadleaved trees, so is more serviceable when it is necessary 

 to use wood that has been recently felled. 



4. The heavier a wood, the more it shrinks when dried.* 

 II. llartig t found that the hardest and heaviest coniferous 

 wood, at bend^ in the stems of trees that he and Cieslar 

 termed " redwood," shrinks less than normal wood. The 

 following law, as stated by Nordlinger, is, however, correct : 

 Branchwood shrinks jiiore than stemwood, the latter more 



* "Xnn[iii)-<>r," issc,. K. I less, 1SS7. 



f li. Hiiriig, Holzuntersaohangeo, Altes u. Neiies." 11)01. 



