102 AGRICULTURE OX THE RHI^^:. 



down very exact general calculations as to the return ob- 

 tained from plantations of these kinds of timber, so great 

 is the influence of soil, climate, and position upon the 

 growth and longevity of the trees. Different authorities 

 that have made the same estimate from experience of a 

 forest to be exterminated and renewed in the course of 

 one hundred years, have arrived at the differing conclu- 

 sions noted in the figin-es of the following table. It sup- 

 poses the term of one hundred years divided into five 

 periods for felling, at each of which the number of cubic 

 feet noted in the table shows the growth of the trees 

 and the planter's gain. The calculations differ as much 

 as thirty-three per cent. 



According to the calculation of the first-named writer 

 a morgen of land ought to produce 4655 cubic feet of 

 timber in a hundred years, while the second estimates 

 a growth of 6584 cubic feet in the same inter- 

 val ; this will show the difficulty of treating the subject 

 briefly and satisfactorily. These figures are taken from 

 tables calculated on observations made in different parts of 

 Germany ; it would be as dangerous, however, to assume 

 an average of these results as a practical guide in forest 

 estimates, as it is to attempt to form a general table of 

 mortality from a combination of scattered materials. The 

 calculation will in both cases be a safer one if it be con- 



