74 Germany. 



A considerable amount of mathematical know- 

 ledge was required for this work of forest organization. 

 The mathematical apparatus of the foresters even 

 at the end of this period was rather slender, but its 

 development went hand in hand with the develop- 

 ment of these methods of regulation; and even elabor- 

 ate mathematical formulae for determining felling 

 budgets were not absent. 



Until nearly the middle of the 18th century, sur- 

 veys of exact nature were almost unknown; only 

 when the division into equal or proportionate felling 

 areas became the basis for determining the felling 

 budgets, did the necessity for such surveys present 

 itself. 



Plane table and compass were the instruments 

 which came into use in the beginning of the 18th 

 century. But not until the latter half of that century 

 were extensive forest surveys and maps of various 

 character made, especially in Prussia under Wed ell, 

 Kropff and Hennert. 



The methods of measurement of wood developed 

 still later. Until Oettelt's time no method of precise 

 determination of volumes was known, everything 

 being estimated by cords or by diameter breast-high 

 and height, or by the number of boards which a tree 

 would make (board feet?). 



The diameter was sometimes used as a price maker, 

 the price increasing in direct proportion to the dia- 

 meter increase. Oettelt calculated the volume of 

 coniferous trees as cones, and Vierenklee, who wrote 

 a book on mathematics for the use of foresters, 

 calculated timbers with the top removed by using the 



