58 FOREST UTILIZATION 



2. Specific gravity times 8,000 times cordwood 



reducing factor equals the weight of a. 

 cord of wood. Reason — 128 cubic feet 

 of water weigh 8,000 lbs. ; a cord of wood 

 contains from 20 % to 85 % of wood, the 

 balance being air. 



3. Specific gravity air dry times 5,200 times 23.. 



equals the weight of 1,000 feet b. m, in 

 the log. Reason — a green log has about 

 10 % bark, about 27 % of water, to be 

 removed by drying, and loses 33 % for 

 slabs and kerf in band sawing. Hence the 

 weight in 1,000 feet b. m. air dried and 

 band sawed lumber is only o.g times 

 0.73 times 0.67 of the weight of a log- 

 scaling 1,000 feet b. m. Doyle. The 

 -weight of a green log is 2.3 times the 

 weight of air dried lumber obtainable 

 from it by the band saw. For broad- 

 leafed species and for circular saws the . 

 figure is higher than for conifers and 

 band saws. 



(f) Heavy planks do not dry as thoroughly as thirt 



boards. 



(g) Weight determines freight and customs charges. 



Also adaptability to packages, floatability in. 

 flumes and rafts and possibility of loose driving. 

 Lumber freight rates from Asheville, N. C, are : 

 29c per 100 lbs. to New York. 

 235/2C per 100 lbs. to Philadelphia. 

 I2>^c per 100 lbs. to Atlanta. 

 i8c per 100 lbs. to Washington. 

 14c per 100 lbs. to Norfolk. 

 Lumber freight rate from Portland, Ore., lo Chi- 

 cago is about 50C per 100 lbs. 

 Steamer rate to Europe from Norfolk is 14c per 



100 lbs. of lumber. 

 The freight rate on logs for 50 miles is at least 

 $S per carload ; for 100 miles at least $6. 

 n. Hardness. 



By hardness is understood the resistance of the fibre to axe 



and saw worked vertically to the fibre. 

 Factors of hardness are : 



(a) Density; wide rings in oak and narrow rings in pine 



increase the hardness. 



(b) Incrustation ; heartwood is harder than sapwood. 



(c) Moisture contents ; dry wood is, on the whole,. 



harder- than green- wood. With some broad- 

 leafed species of loose tissue (willows and cot- 



