BARK. 



51 



Table 21. — Volume of bark per tree and trees per cord — Continued. 



Where bark is peeled from trees cut for lumber it is frequently 

 the custom to reckon the yield by the amount produced to the thou- 

 sand feet of logs, board measure. In the East half a cord to the 

 thousand is considered a fair average, and is equivalent to about 112 

 pounds of tannic acid. On the Pacific coast the thinness of the bark 

 and less economical logging practices unite t'o reduce this proportion, 

 and a quarter of a cord to the thousand is all that can be relied on, but 

 this will average 90 pounds of tannin. The yield per acre is necessa- 

 rily exceedingly variable. For example, Table 11 represents regions 

 where Hemlock forms a given per cent of the total stand of mature 

 timber. Table 16 is for second growth. No figures were obtained for 

 pure, mature Hemlock. The examples given compare favorably with 

 the yield of pure Hemlock land in the East, where the best seldom 

 exceeds 20 cords an acre and the average is about 5. Good authorities 

 place the average crop for Pennsylvania at 7£ cords, for New York 4, 

 and for Maine only 3 cords per acre. Taking a pure 55-year-old stand 

 at South Bend, Wash., as a basis, together with cruising* and meas- 

 urements in other young timber, it lias been possible to figure with 

 approximate accuracy the yield which may be expected from an aver- 

 age well-stocked acre of pure young Hemlock at a given age. The 

 results are shown in Table 22. Only trees 14 inches and over in 

 diameter breasthigh have been considered, and these peeled to a point 

 L2 inches in diameter in the tops. 



