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According to incomplete statistics, there are nearly a hundred different methods for measuring logs in North America alone, with as many as 185 different names. Below are some common measuring methods used in various countries around the world, especially those exported to China.
1) JAS measuring
(Full name: Japanese Agricultural Standard)
--Formulated by the Japanese Agriculture and Forestry Agency in 1841 (the second year of the Opium War).
-- Widely applicable to importing countries such as New Zealand, Australia, Chile, and Japan
--Round the length to the next decimeter; measure the shortest diameter at the smaller end. For logs under 14cm, round to the next centimeter (e.g., 11.8cm is recorded as 11cm); for logs over 14cm, round to the next even-numbered centimeter (e.g., 17.8cm is recorded as 16cm). Note that it is "rounding down" not "rounding to the nearest whole number". Although only the shortest diameter at the smaller end is measured, if the log is "too flat", meaning the difference between the length and shortest diameter at the smaller end exceeds 6cm, then add 2cm to the recorded data.
--Formula (different formulas for lengths under 6m and above!)
For heights below 6m: (D² x L) / 10000
For lengths over 6m: add a coefficient of (length - 4) / 2 to the diameter before applying the formula.
2) Russian timber “GOST” measurement (full name Russian GOST 2708-75)
The standard is very similar to the Chinese national standard, with the main differences being:
--Length: China uses 0.2m rounding up, while the Russian standard retains a 3cm margin and rounds up to 0.25m, discarding any insufficient margins, but retaining the special lengths of 3.8/7.6/8m.
--Diameter: For Chinese standards, the average of the shortest diameter and its perpendicular diameter is taken; for Russian standards, the average of the shortest diameter and the longest diameter is taken.
--The results are obtained by consulting the volume table (but the underlying formulas are slightly different).
In summary, the actual measurement results are approximately as follows:
12-24cm: 10% increase; 26-40cm: 5% increase; 42-52cm: 1.5% increase; 54cm and above: starting to decrease in size!
3) SMALIAN measuring instrument
--Measure the size of the large and small ends to calculate the average area
--The BC METRIC from Canada, which we introduced in the last issue, is a typical SMALIAN measuring instrument.
--Formula: (Small end area + Large end area) x Material length / 2
4) HUBER Measurement
--Common in European countries, Gabon, Africa
--At half the length of the timber, the amount of bark included (this rule has some drawbacks).
--The material length is divided into segments in multiples of 2.7-3.0 meters, and the allowance and defects are deducted.
--Formula: Treat it as a cylinder, just like the Smalian, i.e.: cross-sectional area x length of the timber / 2
Therefore, in theory and practice, the same log will yield different results when measured by Smalian and Huber; for example, a log that is 25cm at the narrow end and 31cm at the wide end, and is 5m long.
Smalian's understanding:
Calculation results:
(0.125²+0.305²)*3.1416*5=0.311m3
HUBER's understanding:
Calculation results:
0.14² * 3.1416 * 5 = 0.308 m³
5) ATIBT Standard (Full name: Association Technique Internatinale des Bois Tropicaux)
Commonly found in Africa, South America, Papua New Guinea, etc.
Similar to SMALIAN measuring, the difference is that it measures the length and short diameter of the log to obtain the average of four data points, which is then used as the "average diameter" to calculate the volume.
The above five methods, along with the North American 1000-board measurement (which was introduced in the previous issue), are the most common methods for measuring imported logs.
In tomorrow's episode of the One Minute series, we will introduce some other diverse methods of measuring.