16 BULLETIN 152, U. S. DEPARTMENT OF AGRICULTURE. 
board feet each are reported to have been cut in Tucker County, 
W. Ya. 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 1 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 CHARACTERISTICS. 
BARK. 
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, "Silva of North America," vol. 12, p. 65, 1898. 
