70 Germwny. 



diameter at any height, similar to some more modern 

 ones, was constructed by Eeinhold. 



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 

 (1783). 



In 178,5 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 wa^ estimated 

 as with us, and only the very roughest estimating or 

 rather guessing was in vogue untU near the end of the 

 period. 



The first attempt at closer measurement was made by 

 Beckman (1756), who surroxmded the area to be meas- 

 ured with twine, drove a colored wooden peg into each 

 tree, one color for each diameter class, when, knowing 



