254 LOGGING 



small isolated tracts, which do not warrant the expense of 

 building a railroad to them. Where a snaking system is used 

 and the aim is to log all parts of the tract by this system, spurs 

 should be placed approximately parallel to each other and 1800 

 or 2000 feet apart, for the maximum efficient radius of the ma- 

 chine does not exceed 1000 feet. In cypress and other forests 

 where the area is logged by the cableway system, the spurs are 

 placed parallel and from 1200 to 1400 feet apart. In mountain- 

 ous sections, spur roads chiefly follow secondary drainage. 

 On the Pacific Coast some operators build their spur roads to 

 the yarding engines. A geared locomotive then drags the logs 

 over the ties to the landing or the logs may be loaded on cars at 

 the yarding engine and transported to destination. Where spur 

 construction is costly the logs may be brought to the main line 

 by road engines, animals, slides or flumes. In the Appalachian 

 region spur construction is limited, and railroads are confined to 

 the larger branches of the streams. 



The grades and curves permissible on spurs are greater than 

 on main lines because a slow speed is maintained, and lighter 

 motive power is used. For the sake of efficiency and safety it 

 is always desirable to keep grades and curves as low as possible, 

 although short spurs may have grades as high as 6 per cent for 

 loaded cars, and from 8 to 10 per cent for empty ones, and curves 

 as high as 40 degrees. 



Geared locomotives, only, are suitable for excessive grades and 

 curves since the short wheel base permits the locomotive to 

 make sharp turns, and because of the increased power secured 

 through the gearing; on steep grades and sharp curves however, 

 a geared locomotive can haul only a few cars at one time. 



Methods of Location. — Topographic maps are now considered 

 an essential part of the equipment of the modern logger operating 

 in a rough region. These often are prepared in connection with 

 the timber cruise, but if they are not available previous to rail- 

 road location, engineers prepare them, using contour intervals of 

 20 or 50 feet depending on the accuracy required and the rough- 

 ness of the country. A successful engineer operating in Washing- 

 ton, on his reconnaissance survey preliminary to location, runs 



