40 Government Forestry Abroad. [224 



light enough through the leaf-canopy to sustain an undergrowth 

 until the trees are nearly ready to give place to their descendants. 

 Such shrubs or seedlings as still appear, thanks to a shade-bearing 

 temperament, are systematically cut out. It may be strongly doubted 

 whether such a policy might safely be applied on soil less moist 

 than that of the Sihlwald; but here, at least, the trees reach the age 

 of sixty years, tall, straight, clean-boled, and in condition to make 

 the best of the last part of the period of maximum growth, which 

 a large number of measurements have shown to occur in general 

 between the ages of seventy and ninety years. A heavy thinning 

 now comes to the assistance of the best specimens of growth, and 

 they are left to profit by it until seven years before the date fixed 

 for their fall. Then begin the regeneration cuttings, whose object 

 is to admit through the leaf-canopy an amount of light, varying 

 with the temperament of each species, whose mission is to give 

 vitality to the seedlings which the trees, stimulated themselves by 

 their more favorable situation, now begin to produce in consider- 

 able quantities. To this end the light which falls from above has 

 a powerful auxiliary in that which the system of felling each year 

 in a long, narrow strip admits from the side, and so admirable is 

 this double method that the time which elapses between the begin- 

 ning and the end of a regeneration is but half the average for less 

 favored localities. This applies only to the deciduous trees. The 

 time required by the conifers is much longer, and the incomplete 

 regeneration which they furnish is supplemented by planting in the 

 blanks already mentioned. But for the self-sown seedlings of both 

 classes the amount of light is gradually increased, the trees which 

 sheltered them are at length wholly removed, and the cycle of 

 growth repeats itself. 



"With an average stand of timber of 2,800 cubic feet per acre, 

 the annual yield of wood, almost half of which is from thinnings 

 alone, reached last year 377,023 cubic feet, an amount which may 

 be taken as slightly above the average. 



" Under the management of Forstmeister Meister the 2,400 acres 

 of the Sihlwald gave last year (1889) a net return of something over 

 $8 per acre, or a total contribution to the treasury of the city of 

 about $20,000. This sum, large as it is in relation to the area of 

 forest which produced it, promises to be materially increased. 



"But with the climate of northern Europe indicated by a mean 

 temperature of forty-eight degrees Fahrenheit, and with the condi- 

 tions of soil and moisture which it enjoys, the exceptional produc- 

 tiveness of the Sihlwald would still remain partly unexplained were 

 it not possible to add that the land which it covers has been unin- 

 terruptedly under forest for something over a thousand years. That 



