Normal Stock Methods. 109 



Carl Heyer (Pelling budget =Ia ). Based 



upon the normal forest idea, a number of methods were 

 elaborated which, because of their employing a mathe- 

 matical formula for the determination of the felling 

 budget, are known as the formula methods; they are, in- 

 deed modified rational volume divisions. Hundeshagen 

 has the merit of having clearly explained the basis of 

 these methods and himself developed a formula, of the 

 correctness of which he was so convinced as to designate 

 his method as "the rational" one. Two other formulae 

 were brought into the world by Koenig (1838-1851), but 

 the credit of the most complete elaboration both of the 

 principles of the normal forest idea and of its practical 

 application belongs to Carl Heyer. The principles of *^ 

 his method are briefly : First determine upon the period 

 of regulation, during which the abnormal forest is to be 

 brought nearly to normal conditions ; the length of this 

 period to be determined with due regard to the financial 

 requirements or ability of the owner and to the condi- 

 tions of the forest. The actual stock on hand is then 

 determined and the increment which will take place dur- 

 ing this period added. Deducting what has been calcu- 

 lated as the proper normal stock requisite for a sus- 

 tained yield management, the balance is available for 

 felling budgets which may be utilized in annual or 

 periodic instalments during the period of regulation. A 

 working plan is provided which takes care of securing an 

 orderly progress of fellings and proper location of age 

 classes, to be revised every ten years. 



Although this is undoubtedly the most rational 

 method yet devised, it has remained largely unused, and A 



