16 BULLETIN 152, U. S. DEPAETMEXT OF AGBICULTX7BE. 



board feet each are reported to have been cut in Tucker County, 

 W. Va. Such dimensions sometimes are found to correspond to an 

 age of 500 or 600 years. 



The average contents in cubic feet and board feet of hemlock trees 

 of different heights and diameters are given in Tables 12 to 17, 

 Appendix. In addition, Tables 21 and 22, Appendix, show the diam- 

 eters, inside bark, at different heights from the ground corresponding 

 to the small ends of 8 and 16 foot logs. 



THE WOOD. 



Hemlock wood is soft, light, stiff, but brittle, not strong, splintery, 

 and commonly cross-grained. Its worst defect, aside from a tendency 

 to decay, is "shake," which is the tearing apart of the wood between 

 annual rings caused by the tree bending in the wind. This condition 

 is very common, especially in old trees. "Shaky" lumber splits so 

 easily as to be worthless for many purposes. 



In color the wood is light buff with a red-brown tinge. In structure 

 it differs from pine and spruce wood in the more abrupt transition 

 between the hard, dark summerwood and the soft, light, spring- 

 wood, a contrast which gives the lumber a handsome figure. The 

 fuel value of hemlock is low, though slightly higher than that of 

 white pine. The per cent of ash is 0.46. Sargent * computes the 

 specific gravity of absolutely dry hemlock wood at 0.4239, a cubic 

 foot weighing 26.42 pounds. The shipping weight per thousand 

 board feet of ordinary seasoned rough lumber varies from 2,400 

 pounds for 1-inch board to 3,500 pounds for heavy timbers. 



BOTANICAL CHAEACTEEISTICS. 



The bark of merchantable trees in the Lake States comprises about 

 19 per cent of the total cubic volume, and this proportion varies but 

 little with the size of the tree. In the Southern Appalachians the 

 proportion varies from 15 per cent for 6-inch trees to 19 per cent for 

 trees 26 inches and over. When 15 or 20 years old the bark begins 

 to break up into thin, partly loosened flakes, or scales, and still later 

 becomes traversed by deep, longitudinal fissures. In old trees the 

 bark is often 2 or 3 inches thick at the stump, gradually decreasing 

 with height to a thickness of from 0.3 to 0.5 of an inch at the point 

 where the tree is 6 inches in diameter. It consists of two distinct 

 layers, the inner relatively very thin, white, and fibrous, the outer 

 thick, deep red, and brittle. 



ROOTS. 



Seedlings form a slender taproot during the first year, which is later 

 lost in the development of lateral branches. These are numerous, 



i C S. Sargent, "Suva of North America," vol. 12, p. 65, 1898. 



