. Report upon the forestry investigations of the U. S. Department of agriculture. 1877-1898. Forests and forestry. 96 FORESTRY INVESTIGATIONS U. S. DEPARTMENT OF AGRICULTURE. Since the proportion of sap and heart wood varies with size, age, species, and individual, the following figures must be regarded as mere approximations: Pounds of water lost in drying 100 pounds of green wood in the Jcihi. v (1) Pines, cedars, spruces, and firs (2) Cypress, extremely variable (3) Poplar, Cottonwood, basawood (4) Oak, beech, ash, elm, maple, birch, hickory, chestnut, walnut, and sycamore Sapwood or outer
. Report upon the forestry investigations of the U. S. Department of agriculture. 1877-1898. Forests and forestry. 96 FORESTRY INVESTIGATIONS U. S. DEPARTMENT OF AGRICULTURE. Since the proportion of sap and heart wood varies with size, age, species, and individual, the following figures must be regarded as mere approximations: Pounds of water lost in drying 100 pounds of green wood in the Jcihi. v (1) Pines, cedars, spruces, and firs (2) Cypress, extremely variable (3) Poplar, Cottonwood, basawood (4) Oak, beech, ash, elm, maple, birch, hickory, chestnut, walnut, and sycamore Sapwood or outer part. 45-65 50-G5 50-65 40-50 Heartwood or interior. 16-25 18-60 40-60 30-40 The lighter kinds have the most water in the sapwood, thus* sycamore has more than hickory. Since the shrinkage of our woods has never been carefully studied, and since wood, even from the same tree, varies within considerable limits, the figures given in the following table are to be regarded as mere approximations. The shrinkage along the radius and that along the tangent (parallel to the rings) are not stated separately in the following table, and the figures represent an average of the shrinkage in the two directions. Thus, if the shrinkage of soft pine is given at 3 inches per hundred, it means that the sum of radial and tangential shrinkage is about 0 inches, of which about 4 inches fall to the tangent and 2 inches to the radius, the ratio between these varying from 3 to 2, a ratio which practically prevails in most of our woods. Since only an insignificant longitudinal shrinkage takes place (being commonly less than inch per hundred), the change in volume during drying is about equal to the sum of the radial and tangential shrinkage, or twice the amount of linear shrinkage indicated in the table. Thus, if the linear average shrinkage of soft pine is 3 inches per hundred, the shrinkage in volume is about 6 cubic inches for each 100 cubic inches of fresh wood. Approximate shrinkage of a hoard,
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