136 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



of sections averaged the more accurate the result will be. If, 

 for instance, we take a sectional area at every 3 feet, i.e. at every 

 inch of diameter from butt to tip of the above log, and take the 

 average of all these sections and multiply by the length, the 

 result will be as follows : — 



Volume calculated from average of Thirteen sections. 



Sect. Ar., Cub. Conts. , 

 Sq. Ft. Cub. Ft. 



A b + A, + A 6 + A.+ A t L 1613-206 _, , 



— 3 ° 9 t x — _ j = -861x36 30-996 



13 144 13 x 144 



Thus the rules of Newton and Hossfeldt are undoubtedly the 

 most accurate. Huber's rule gives a less and Smalian's a 

 greater result, but it should be noted that this difference depends 

 entirely on the degree of taper on the log. If the log has no 

 taper, the results will be the same in every case. On the other 

 hand, the greater the degree of taper, the greater will be the 

 discrepancy between these rules. 



For the ordinary measurement of round timber, however, 

 Huber's rule will be found the most convenient, and provided 

 that two diameters are taken at right angles to each other, and 

 averaged before the sectional area is calculated, a sufficiently 

 accurate result will be obtained for all practical purposes. 



In the writer's opinion, this rule, which is in general use in 

 Europe, should be adopted in our country. It would be a 

 distinct step in advance on the old system, and should prove 

 most satisfactory for forestry work, both scientific and practical, 

 in the future. 



When calculating the volume of standing timber by means of 

 basal area, i.e. the area of the cross-section of the stem taken at 

 breast-height multiplied by the height and form-factor, it is 

 quite absurd to proceed by using the quarter-girth rule, as the 

 result of the following surveyed plot shows. The species dealt 

 with was Scots pine, with a mean height of 49 feet and 93 years 

 of age. The area of the plot surveyed was -184 acres. As the 

 girth measurement only was used when the plot was surveyed, 

 the only comparison which can be made is between the results 

 as calculated from quarter-girth and full girth. The quarter- 

 girth system shows a volume per acre of 41x0 cubic feet, and a 

 basal area per acre of 206 square feet, whereas by calculating 

 from full girth measurements, the volume per acre amounts to 



