Following an earlier article, it is claimed that the height/diameter curve, in the “main stem” of all normally grown forest trees, is parabolic; so that for this length, the height/sectional area relationship is linear. Other than the variation in the height/diameter ratio of different trees, variation of “taper” results chiefly from differences of stem profile in the crown and at the butt. The “taper line” is defined as the graphical linear relation, in the main stem, between height and sectional area. Projection of the taper line to intercept the vertical and horizontal axes at “parabolic height” and “parabolic base” respectively, gives a triangle, from which “parabolic volume,”— vp—, can be computed, from the formula: — vp = ½ height x base. The units of measurements used in this article are feet, square feet and cubic feet, for height, sectional area and volume respectively. (Metric, or other units, can course be used if desired.) For plantation grown coniferous trees, and for “second growth” crops in general, experience suggests that parabolic volume will ordinarily be found to be a close approximation to total stem volume; and in such crops therefore, to be a universal unit for comparative purposes. (For very large, old, umbrageously crowned and irregularly shaped trees, precise estimation of volume is not possible by any practicable method. Often when it is practicable, it may not be warranted, because of hidden defects, etc.). Other important uses of the taper line method of measurement are detailed, e.g.:-