888 JOURNAL OF FORESTRY 



For Pine, site II, the values, under the same conditions, are : 



Per cent. 



Rotation, 60 years, yield tax 8.4 



Rotation, 80 years, yield tax 9- 1 



Rotation, 100 years, yield tax 9-3 



Rotation, 120 years, yield tax 9-5 



Rotation, 140 years, yield tax 9-6 



For Oak, site II, and taking the full values as given by Schwappach, 

 the values run from 10 to 10.8 per cent for rotations from 80 to 200 

 years. 



This comparison may be put into the following general form : 



(A-A(.opjXioX^Xioo 



X- =^^ 



where A := gross income. 



pj = per cent which expenses are of the gross income. 

 Py = per cent of yield tax under the conditions assumed, particularly the 

 12 per 1,000 property tax rate. 



The above general form reduces to : 



(l — O.OPx) 12 = Py 



In a concrete case : If the expenses are 30 per cent of the gross in- 

 come, then [i ^\ 12 = 8.4 as the per cent of yield tax. In 



other words, where the expenses are kept at a certain proportion of the 

 gross income the yield tax remains constant, as per the above method 

 of calculation. 



Since the expenses in any business naturally are adjusted to the gross 

 income as far as possible, and also since the expenses in regular forestry 

 work are commonly stated as a per cent of the gross income, this state- 

 ment is convenient. 



What is the per cent which the expenses make of ordinary gross in- 

 come? 



In farming, it runs from about 50 per cent to 80 per cent and varies 

 much with crop and season. In forestry it is evidently much lower, as 

 shown by the statistics of the German State forests, which are managed 

 economically, but not with any false economies. According to Endres, 

 Graner, and others, the expenses are about 30 per cent of the gross in- 

 come in Wiirttemberg and Saxony and about 50 per cent in Bavaria 

 and Prussia, with a tendency to decrease. For various reasons, it ap- 

 pears doubtful if this per cent will ever go below 30, but it is also quite 

 certain that it will not, should not, and need not go above 50 per cent. 



