Chapter 16

tear or damage the bark of trunks of standing timber. If possible, only the trees of unimportant timber species should be cut for making corduroy roads in the forests. This will be a saving of valuable material.

In lumbering operations as practiced in this country, the logs are usually moved to the sawmills on sleds or by means of logging railroads. If streams are near by, the logs are run into the water and floated to the mill. If the current is not swift enough, special dams are built. Then when enough logs are gathered for the drive, the dam is opened and the captive waters flood away rapidly and carry the logs to the mill. On larger streams and rivers, the logs are often fastened together in rafts. Expert log drivers who ride on the tipping, rolling logs in the raging river, guide the logs on these drives.

On arrival at the sawmill, the logs are reduced to lumber. Many different kinds of saws are used in this work. One of the most efficient is the circular saw which performs rapid work. It is so wide in bite, however, that it wastes much wood in sawdust. For example, in cutting four boards of one-inch lumber, an ordinary circular saw wastes enough material to make a fifth board, because it cuts an opening that is one-quarter of an inch in width. Band saws, although they do not work at such high speed, are replacing circular saws in many mills because they are less wasteful of lumber. Although sawmills try to prevent waste of wood by converting slabs and short pieces into laths and shingles, large amounts of refuse, such as sawdust, slabs and edgings, are burned each season. As a rule, only about one-third of the tree is finally used for construction purposes, the balance being wasted in one way or another.