FOREST EXPLOITATION-" DBS COMPARTIMENTS." 4? 



these trees, the rate of their annual increase at different 

 ages, the age or ages at which they respectively attain 

 their maximum of growth, and at which they attain their 

 maximum of value these, and twenty other points, must 

 be determined to furnish the data necessary to determine 

 equivalent partitions ; and such partitions are necessary 

 in order to ensure the full benefits of this method of 

 forest management being secured. 



If by a tentative process, based on superficial extent, as 

 it necessarily must be, modified in accordance with the 

 number of trees, and with the cubic contents of these, it 

 be sought to arrive at a division of a forest into equivalent 

 partitions, it will be found that constant modifications of 

 the division first made are seen to be necessary. And 

 the substitution of equivalent for equal partitions led to 

 other devices to secure what was wanted, equal annual, 

 decennial, centennial, or other periodical supplies of pro- 

 ducts. To secure this, successive thinnings of different 

 portions were made to contribute to the supply along 

 with what was obtained by definitive fellings ; and while 

 in one division of the cycle this might be secured by the 

 produce of the first thinning of the partition A, and the 

 produce of a second thinning of partition F, and the defini- 

 tive felling of partition W ; in another it might be obtained 

 by the definitive felling of F, and a second thinning of A, 

 and the first felling or thinning of a secondary crop grow- 

 ing on partition N ; and like equivalent supplies might 

 have been in intervening periods, and afterwards in suc- 

 ceeding ones, obtained by other combinations. 



The combinations which occur in practice are numerous, 

 to the tyro they might seem complicated, and a fuller 

 statement in regard to them confusing. All that is con- 

 templated here is to show wherein La Methode des Com- 

 partiments differs from La Methode a tire et aire, and to 

 show that that may be considered a development of this, 

 with the history of which we are at present occupied. 



