. Canadian forest industries January-June 1923. Lumbering; Forests and forestry; Forest products; Wood-pulp industry; Wood-using industries. THE GREAT NATIONAL LUMBER JOURNAL Pioneer and Leader ##I11/T/1/T IllfTI l\A1*tTl/W Recognized Authority in the InduStry lUllUUU I llllljjfcl 111U11 <°r Fort? Yea s â * M * ybundcd 1880 Vol. 43 Toronto, January 15, 1923 No. 2 The Effect of Growth Rate on Strength of Softwoods By J. D. Hale and M. J. Brophy Dominion Forestry Branch Forest Products Laboratories of Canada, Montreal Everyone, who has used an axe, knows the layered structure of wood. From t
. Canadian forest industries January-June 1923. Lumbering; Forests and forestry; Forest products; Wood-pulp industry; Wood-using industries. THE GREAT NATIONAL LUMBER JOURNAL Pioneer and Leader ##I11/T/1/T IllfTI l\A1*tTl/W Recognized Authority in the InduStry lUllUUU I llllljjfcl 111U11 <°r Fort? Yea s â * M * ybundcd 1880 Vol. 43 Toronto, January 15, 1923 No. 2 The Effect of Growth Rate on Strength of Softwoods By J. D. Hale and M. J. Brophy Dominion Forestry Branch Forest Products Laboratories of Canada, Montreal Everyone, who has used an axe, knows the layered structure of wood. From the beginning of its life as a seedling until its vital activity ceases, a tree increases the girth of its trunk, (branches and roots every year by covering its previously-formed wood with a new layer. In the wood of Canadian trees, the successive layers are dis- tinctly visible on a transversely-cut log as a series of concentric rings. As each ring represents the amount of wood added during a year's growth the layers are commonly termed "annual ; (See Fig- !)⢠Wood is composed of cells which are chiefly fibres. The fibres vary in length from about one millimetre to six or even eigiht milli- metres. This length may be from twenty-five to one hundred and fifty times the diameter of the fibres. Wood-fibres are hollow tube- like structures with ends which are closed and more or less blunt. Packed close together with their long axes parallel to the axis of the trunk or branch whose wood they compose, the fibres and other wood-cells, by the combination of their own properties, determine the properties of wood. If wood-cells were all of uniform dimension, wood-structure would appear homogeneous and the different annual layers would not be distinguished from each other. The seasonal changes in northern latitudes, however, exert a marked effect upon the cell growth, an effect manifested by a decrease in size of those wood- cells which are formed near the latter hal
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectforests, bookyear1923
