i6o Forestry Quarterly. 



in computing the volume of the tree at different periods — is the 

 somewhat laborious and involved method of determining the 

 dimensions of the tops (above the last cross-cut), in preceding 

 decades. These tops are generally regarded as cones (see 

 Graves' "Mensuration," page 292), and their volumes computed 

 as such. The difficulty arises in obtaining the heights of the sev- 

 eral cones as they appeared further and further within the top, 

 or down the stem, with each preceding decade. The method de- 

 scribed by Professor Graves, namely, to take a distance propor- 

 tional to the number of years required to grow the distance be- 

 tween the two sections in question, thus assuming a regular rate 

 of growth for the period, is quite accurate, but it is likely to 

 confuse the student, and has been the cause of more errors in com- 

 putation than any other one factor, according to my observation.* 



In German text books the method described for obtaining the 

 volumes of the tree in preceding decades frequently disregards 

 these small cones, or tips, because the sections into which the tree 

 is divided for analysis are short, — rarely more than 2 meters. 

 The volumes are therefore relatively insignificant. In this coun- 

 try, however, where we have to compute stem analyses from 

 trees where a top of 15, 20, or even 30 feet is left, it becomes 

 necessary to include these tops, and their dimensions at different 

 periods, otherwise the calculated volumes would be inaccurate to 

 such a degree that they would be of no scientific value. Some 

 way must be devised, therefore, which will yield accurate results, 

 and at the same time will be readily understood and applied by 

 the student. 



In the hope of simplifying the work of making and recording 

 stem analyses, and eliminating some of the obvious causes for 

 mistakes in the calculations, the following suggestions are made. 

 Nothing new or original is claimed for these suggestions ; on the 

 contrary, they have all been prompted by a perusal of the stand- 

 ard German text books. They are presented here simply for the 

 purpose of showing how the work may be made more logical, and 



* It has even led to an error in the very example chosen to illustrate the 

 niethod (page 291 in "Forest Mensuration"), where, in the computations 

 for the tree as it was 30 years old, the length ascribed to the tip is 475 

 feet. Since the tip at that age comprised 10/16 of the length of the section 

 (10 feet) it should evidently be 6.25 feet, and not 4.75 feet, as printed. 



