HARMONIZED CURVES BASED ON HEIGHTS 



173 



and the new values then replotted from this table. In this case, the 

 values from each curve will be read horizontally from the table instead 

 of from the vertical 

 column as in the first ^ 

 instance. 



"Strip" Method of 

 Replotting. A rapid 

 method of replotting 

 direct from the curve is 

 by means of a strip of 

 paper. The zero or end 

 of strip is placed on the 

 base or abscissa, and 

 held in a vertical posi- 

 tion, so that the edge 

 lies on the ordinate re- 

 presenting the diameter 

 class to be transferred; 

 a mark is then made 

 where the curve of vol- 

 ume for each successive 

 height class intersects 

 the strip. These marks 

 may be numbered or 

 otherwise designated, 

 but their mere order is 

 a sufficient identifica- 

 tion. Transferring this 

 paper to the second 

 sheet, the vertical or 

 ordinate distance (which 

 represents volume in 

 each set of curves) for 

 the first height class, 

 is plotted on the ordi- 

 nate intersecting the 

 abscissa representing 

 that height. The strip 

 is then moved to the 

 right, to intersect the 

 next' height on the scale 

 and the corresponding 

 volume point transferred 



to the sheet. When plotted thus, these volumes indicate the position of the 

 curve of volume for different heights, for trees of the given diameter class. ^ 



6 40 



3 35 



Height-, Peefe 



Fig. 29. — Curves of volume based on height. Original 

 curves, dotted, from curves shown in Fig. 28, or 

 values from Table XXIX. Harmonized curves 

 drawn. 



1 This method is described by W. B. Barrows, "Reading and Replotting Curves 

 by the Strip Method," Proc. Soc. Am. Foresters, Vol. X, 1915, p. 65. 



