CAUSES OF DIMINISHED SUPPLY OF WOOD. 149 



Cases have come under my notice in which the revolu- 

 tion or cycle had been determined thus : a year's supply 

 of fuel would clear a certain area of forest ; the entire 

 forest contains a hundred times that area ; it is divided 

 into ten sections, and a decade is assigned to the exploita- 

 tion of each section. The only factors here are the require- 

 ment and the area, without regard to the annual or centen- 

 nial production of wood, which should have been treated as 

 the most important factor of the three. In consequence of 

 this all may go well for a hundred years ; but it will be 

 otherwise in the hundred years which follow these ; and 

 again in the hundred years which follow them. 



It would have been more reasonable to have ascertained 

 what was the measurement of the annual or centeuial pro- 

 duction of wood, and to have divided the area in accord- 

 ance with this produce instead of in accordance with the 

 demand. Nor is it any objection to this that in that case 

 the work for which the fuel is required must be limited 

 accordingly. The limitation must come sooner or later, 

 and it is bad economy to kill the goose that lays the 

 golden egg. 



A like principle is applicable to forests yielding timber; 

 but it is in connection with forests yielding fuel that the 

 subject comes under consideration here. And in connection 

 with this it falls to be mentioned that the determination 

 of the measurement of wood produced in a year, a decade, 

 or a century, is more complicated than may at first be 

 supposed. 



The relative increase in cubic measurement varies in a 

 tree at different ages. It does so to such an extent that 

 in trees which grow vigorously to the age of 150 years 

 more wood may be obtained in the course of 300 years 

 from three fellings, a hundred years apart, than from two 

 fellings 150 years apart. And in coppice, possibly more 

 wood may be obtained in 300 years by felling once in forty 

 years than by felling only once in sixty years. The age at 

 which trees should be felled with a view to procure from 

 them tho maximum of produce, whether of timber or of 



