FOREST MENSURATION. 187 



log. Usually the cut exceeds the scale. Take, for ex- 

 ample, a log sixteen inches in diameter at the small end, 

 eighteen inches at the middle, twenty inches at the large 

 end, and twelve feet long. Such a log contains about 

 21.2 cubic feet. The official scale gives 119 feet B. M., 

 which is equal to 9.9 cubic feet. The actual cut should 

 give 155.75 feet B. M., or thirteen cubic feet of lumber, 

 the slab would be about 5.3 cubic feet, and the kerf (saw- 

 dust) about 2.9 cubic feet. From this it would appear 

 that the Minnesota official scale (i.e. Scribner's Rule) 

 gives the seller 46.7 per cent, of his log, while the mill 

 turns out 61.3 per cent, in lumber, 13.7 per cent, in sawdust, 

 and 25 per cent, in slab. The producer loses 53.3 per cent, 

 of the scaled log; but that is not all his loss. In marking 

 logs to be cut the undercutter allows at least three inches 

 over the required length to cover loss in checking; that 

 is, a log scaled at twelve-foot length would really measure 

 twelve feet and three inches or more. 



The Percentage of the Logs on which the seller or pro- 

 ducer gets returns by Scribner's Rule varies with different 

 sizes and shapes. The table on p. 188 will serve as a com- 

 parison : 



In practice these discrepancies are equalized as the 

 result of the ordinary trade relations, and are not liable to 

 work serious injustice under present conditions, and are 

 here stated only to call attention to our crude methods 

 of measuring timber. 



INSTRUMENTS USED IN FOREST MENSURATION. 



The Equipment of a Forester, while not extensive, must 

 be complete for the work in hand. He surveys the land, 

 lays out roads and ditches, cuts down trees and saws them 

 into logs, measures diameters of logs and growing trees, 

 takes heights of trees, determines rates of growth, estimates 

 and measures timber and cordwood, and maps and plats 



