70 Germany. 
diameter at any height, similar to some more modern 
ones, was constructed by Reinhold. 
Determination of the real wood contents in a cord of 
wood and of the volume of bark by measurement was 
taught by Oettelt, and the method of immersion in 
water and measuring the displaced volume, by Hennert 
(1782). 
In 1785 Krohne first called attention to the variation 
of the accretion in different age classes and the need of 
determining the accretion for each separately. 
In 1789 Trunk taught how to determine average fell- 
ing age accretion, and also the method of determin- 
ing the change of diameter classes, which is now used 
by the United States Forestry Bureau: “On good soil 
a tree grows one inch in three years, on medium soil in 
four years, on poor soil in five years.” With this knowl- 
edge the attainment of a given diameter, or the change 
from one diameter or age class to the next could be 
calculated. 
Volume tables were at Trunk’s command, and Paulsen 
in 1787, Kregting in 1788, mention periodic yield 
tables; but generally speaking “ocular taxation” or esti- 
mating was the rule, checked by experience in actual 
fellings, the method of the American timber looker. 
Generally, of course, only the log timber was estimated 
as with us, and only the very roughest estimating or 
rather guessing was in vogue until near the end of the 
period. 
The first attempt at closer measurement was made by 
Beckman (1756), who surrounded the area to be meas- 
ured with twine, drove a colored wooden peg into each 
tree, one color for each diameter class, when, knowing 
