A large modulus indicates a stiff material. Thus in green wood tested in static bending it varies from 643,000 pounds per square inch for arborvitæ to 1,662,000 pounds for longleaf pine, and 1,769,000 pounds for pignut hickory. (See Table IX.) The values derived from tests of small beams of dry material are much greater, approaching 3,000,000 for some of our woods. These values are small when compared with steel which has a modulus of elasticity of about 30,000,000 pounds per square inch. (See Table I.) |------------------------------------------------------------------------------| | TABLE I | |------------------------------------------------------------------------------| | COMPARATIVE STRENGTH OF IRON, STEEL, AND WOOD | |------------------------------------------------------------------------------| | | Sp. | Modulus of | Tensile | Crushing | Modulus | | MATERIAL | gr., | elasticity | strength | strength | of | | | dry | in bending | | | rupture | |-------------------------+----- +------------+----------+----------+----------| | | | Lbs. per | Lbs. per | Lbs. per | Lbs. per | | | | sq. in. | sq. in. | sq. in. | sq. in. | | | | | | | | | Cast iron, cold blast | | | | | | | (Hodgkinson) | 7.1 | 17,270,000 | 16,700 | 106,000 | 38,500 | | Bessenger steel, | | | | | | | high grade (Fairbain) | 7.8 | 29,215,000 | 88,400 | 225,600 | | | Longleaf pine, | | | | | | | 3.5% moisture (U.S.) | .63 | 2,800,000 | | 13,000 | 21,000 | | Redspruce, | | | | | | | 3.5% moisture (U.S.) | .41 | 1,800,000 | | 8,800 | 14,500 | | Pignut hickory, | | | | | | | 3.5% moisture (U.S.) | .86 | 2,370,000 | | 11,130 | 24,000 | |------------------------------------------------------------------------------| | NOTE.--Great variation may be found in different samples of metals as well | | as of wood. The examples given represent reasonable values. | |------------------------------------------------------------------------------| TENSILE STRENGTH