192 VOLUME TABLES FOR PIECE PRODUCTS 



1. For trees of larger diameter, to show the number of ties which 

 can be obtained from each bolt, hence from the tree. 



2. To show the number of ties of different grades as determined 

 by size, which can be obtained from each bolt, and from the tree. 



This latter requisite also applies to bolts from which but one tie. 

 can be cut. 



A good example of a tie-volume table is that prepared ' for western larch and 

 Douglas fir, Kootenai National Forest, Idaho, in 1919, for the five standard grade? 

 of hewn railroad ties specified by the U. S. R. R. Administration. The dimensions 

 called for are: 



No. 1. 6 inches by 6 inches by 8 feet. 

 No. 2. 6 inches by 7 inches by 8 feet. 

 No. 3. 7 inches by 7 inches by 8 feet. 

 No. 4. 7 inches by 8 inches by 8 feet. 

 No. 5. 7 inches by 9 inches by 8 feet. 



Each tree was measured at 8-foot intervals for diameter inside bark. The 

 method was to construct a taper table (§ 167) from which the sizes of pole ties 

 which could be cut from each bolt were determined. The steps were: 



1. Determine the average top diameter inside bark required to produce a tie 

 for each standard size. These were: 



For No. 1. 8.5 inches. 

 No. 2. 9.2 inches. 

 No. 3. 9.9 inches. 

 No. 4. 10.6 inches. 

 No. 5. 11.4 inches. 



2. Separate the trees measured into D.B.H. and height classes. The height 

 classes used were the number of 8-foot lengths in the merchantable bole, to a top 

 diarneter of 8.5 inches. 



3. Determine the average diameter at each 8-foot point, for the trees in each 

 of these separate groups. This gives a series of taper measurements and an average 

 form for the tree. 



4. With distance above stump as the independent variable, on the horizontal 

 scale, and top diameter of each tie (each 8-foot point) as the dependent variable 

 on vertical scale, plot the average diameter at each 8-foot point. By connecting 

 these points the form of the tree is shown. These curves are used to smooth out 

 irregularities in values. 



5. From the average upper diameter of each 8-foot bolt, for trees of each D.B.H. 

 class, and separate height classes, as 5-tie trees, 6- tie trees, etc., the class of tie 

 which can be cut from each bolt is indicated, and the number of ties of each grade 

 in the tree is shown. This constitutes the tie-volume table. Instead of recording 

 merely the total number of ties, regardless of grade, which could be done without 

 the table, the estimator now has his products classified. 



The same method can be used for trees whose dimensions permit of sawing or 

 splitting two or more ties from one bolt, but usually trees of this diameter will 

 be measured in part as sawlogs in board feet rather than as sawed or split ties. 



1 James W. Girard and W. S. Schwartz. 



