no 



ENGINEERING ON THE FARM 



arc rolled down steep slopes, slid down timbered chutes, 

 and floated down on water confined in timber flumes. In 

 countries where the topography docs not permit of the 

 hauling to streams on ice roads or the temperature does 

 not go low enough to form such roads, special narrow- 

 gauge railroads are built for hauling the logs, which may 

 be brought to the loading place by long cables and winding 

 engines and loaded with derricks and other power appli- 

 ances. In the earlier days, and to a limited extent at the 

 present time, rafts were formed on large streams by means 

 of logs placed side by side and held in position by timbers 

 and wooden pins. These are floated or towed to the mill, 

 which is asually at the site of the final disposition of the 

 lumber. 



From the time the log reaches the mill until it is ready 

 to be piled in the yard in the form of commercial lumber, 

 it is handled almost entirely by mechanical means, the mill 

 men giving their attention to the operation and care of the 

 machinery. The log, if it is to be cut in thin lumber, may 

 be sawed in two ways: by slash or straight sawing (Fig. 

 in), in which the entire log is cut by passages of the saw 

 parallel to the long axis; and by quarter sawing, in which 

 the log is first divided into quarters by the saw, each quarter 



being cut into planks either radially 

 from the center or parallel to one side. 

 By the first method the greatest width 

 of boards can be secured, but each will 

 have sapwood at the edges and heart- 

 wood at the center, will not dry uni- 

 formly, and is therefore liable to warp 

 and shrink. This is considered the 

 Fig. in Boards pro- poorest method of sawing. The 



duced bv straight . 



sawing greater part of the gram or annular 



rings are parallel to the face, and the lumber is known as 

 flat, slash, or straight-grained. In the second method 

 shrinking and warping are reduced to a minimum and the 



