_Grain_--The grain of wood is not a definite quality. The word does not mean the same thing to all who use it. It sometimes refers to rings of yearly growth, and in that sense a narrow-ringed wood is fine grained, and one with wide rings is coarse grained. A curly, wavy, smoky, or birdseye wood does not owe its quality to annual rings, yet with some persons, all of these figures are called grain. The term sometimes refers to medullary rays, again to hardness, or to roughness. Some mahogany is called “woolly grained” because the surface polishes with difficulty. The pattern maker designates white pine as “even grained”, because it cuts easily in all directions. The handle maker classes hickory as “smooth grained”, because it polishes well and the sole idea of the maker is smoothness to the touch. There are other grains almost as numerous as the trades which use wood. In numerous instances “figure” is a better term than “grain.” Feather mahogany, birdseye birch, burl ash, are figures rather than grains. There is no authority to settle and decide what the real meaning of grain is in wood technology. It has a number of meanings, and one man has as much authority as another to interpret it in accordance with his own ideas, and the usage in his trade. It is a loose term which covers several things in general and nothing in particular. _Weight_--The weight of wood is calculated from different standpoints. It has a green weight, an air-dry weight, a kiln-dry weight, and an oven-dry weight. All are different, but the differences are due to the relative amounts of water weighed. Sawlogs generally go by green weight; yard lumber by air-dry or partly air-dry weight; while the wood used in ultimate manufacture, such as furniture, is supposed to be kiln-dry. The absolute weight of wood, with all air spaces, moisture, and other foreign material removed, is about 100 pounds per cubic foot, which is 1.6 times heavier than water; but that is not a natural form of wood. It is known only in the laboratory.