[Footnote 3: See Brush, Warren D.: A microscopic study of the mechanical failure of wood. Vol. II, Rev. F.S. Investigations, Washington, D.C., 1912, p. 35.]
[Footnote 4: See Circular No. 18, U.S. Division of Forestry: Progress in timber physics, pp. 13-18; also Bulletin 70, U.S. Forest Service: Effect of moisture on the strength and stiffness of wood, pp. 42, 89-90.]
[Footnote 5: See Bulletin 70, op. cit., p. 129.]