Outside of food products, no material is so universally used and so indispensable in human economy as wood. (Fernow, _Econ._, p. 21.) The importance of forest products may also be learned from a mere list of the varied uses to which they are put. Such a list would include: fuel, wood and charcoal; houses (over half the population of the United States live in wooden houses); the wooden parts of masonry and steel buildings; scaffolding; barns, sheds and outhouses; ships, with all their parts, and the masts and trim of steel ships, boats and canoes; oars and paddles; railway ties (annual expenditure $50,000,000), railway cars, a million in number; trestles and bridges (more than 2,000 miles in length); posts and fencing; cooperage stock (low estimate, $25,000,000 annually); packing crates, including coffins; baskets; electric wire poles (annual cost about $10,000,000); piles and submerged structures, like canal locks and water-wheels; windmills; mining timbers (yearly cost, $7,500,000), indispensable in all mining operations (for every 100 tons of coal mined, 2 tons of mining timber are needed); street paving; veneers ($5,000,000.00 worth made annually); vehicles, including carriages, wagons, automobiles and sleighs; furniture; machines and their parts; patterns for metal molding; tools and tool handles; musical instruments; cigar boxes; matches; toothpicks; pencils; (315 million a year in the U. S., requiring over 7 million cubic feet of wood); engraving blocks; shoe lasts, shoe trees and parts of shoes; hat blocks; agricultural implements; hop and bean poles; playthings and toys, for both children and adults; Christmas trees and decorations; pipes; walking sticks; umbrella handles; crutches and artificial limbs; household utensils; excelsior. Products other than wood: Turpentine and resin (worth $20,000,000 a year); tar; oils; tan-bark, 1-1/2 million cords (worth $13,000,000 a year); wood alcohol; wood pulp (worth $15,000,000 a year); nuts; cellulose for collars, combs and car wheels; balsam, medicines; lampblack; dyes; paper fiber (xylolin) for textiles; shellac and varnish ($8,500,000 worth imported in 1907); vinegar and acetic acid; confections (including maple sugar and syrup at $2,500,000 a year). (3) The _Esthetic_ and sentimental uses of the forest, tho not to be estimated in dollars and cents, are nevertheless of incalculable benefit to the community. They would include the use of the forest as pleasure grounds, for hunting, fishing, camping, photography, and general sightseeing. Notable instances of the growing appreciation of these uses of the forest are the reservation of the Yellowstone and Yosemite Parks as pleasure grounds. PRESERVATION. The second object of forestry is the preservation of the forest, or continued reproduction. In addition to obtaining crops of trees, the forester plans to keep the forest in such condition that it will constantly reproduce itself and never become exhausted.