Color brownish, sapwood lighter, close-grained, compact structure. Structural Qualities of Wood. Hard, heavy, tough. Weight of Seasoned Wood in Pounds per Cubic Foot. 46. Modulus of Elasticity. 740,000. Modulus of Rupture. 10,200. Remarks. [p040] MAPLE. (_Acer_.) The maples grow on all of the continents of the northern hemisphere. Nearly one half of the known species belong in China, Japan, and the Orient. The principal European species (_Acer pseudo-platanus_) is the European sycamore.[25] The hard or sugar maple (_Acer saccharum_) is one of the principal deciduous trees of North America. Maple wood[26] is characterized by its appearance and by its fine compact texture. The first quality is so marked that selected pieces take rank among the most beautiful of cabinet woods; the last is so pronounced as to fit it for carvings and even for type. "Birdseye," "blister," and "curly" maples are not from different species, but are the results of fibre distortions, possible in some form in any tree of any species, but peculiarly liable to occur in the maple; birdseye and blister effects for the most part in the hard maples, curly effects in the hard, but generally in the softer, species. The distortions do not occur in all trees, and it is seldom possible to tell whether the woods are thus figured until after the trees have been cut. Maple wood shrinks moderately, stands well in protected places, is strong, tough, but not durable when exposed. Pores are not arranged in circles, but are scattered irregularly throughout the layers. Maple is used for ceiling, flooring, panelling, car and ship construction, shoe-lasts, shoe-pegs, furniture, school supplies, implements, and machinery. Sugar is principally, although not exclusively, present in the sap of the sugar maple.[27] The softer species are sometimes [p041] tapped, and sugar is also present in the sap of other trees, such as the butternut and birch. A sugar maple will, on an average, produce about twenty-five gallons of sap, containing a total of about six pounds of sugar, in a season. [Illustration: PLATE 8. SUGAR MAPLE (_Acer saccharum_).] [Illustration: "Curly" Maple Wood (_dissection_).] The Boxelder (_Acer negundo_) is a true maple, remarkable in that it is widely distributed from Canada to Mexico and from the Atlantic to the Rocky Mountains, on low bottom lands, and at elevations of five thousand and six thousand feet.[28] The trees are beautiful and, like other maples are valued for ornamental purposes. The soft, light wood is not particularly noted, although occasionally used for woodenware, interior finish, and paper-pulp. Small quantities of sugar are present in the sap of this tree. [Illustration: _a_, Box Elder. _b_, Hard or Sugar Maple. _c_, Soft or Red Maple. _d_, Soft or Silver Maple.]