138 FORESTS AND MANKIND 



power and capacity before whose saws the forests shrink with 

 appalling rapidity. Last of all when the country has been cut 

 over, these great mills move on, and once again come the 

 smaller mills cleaning up the isolated patches of timber and 

 seeking out whatever discarded material may happen to 

 remain. 



So there has been no permanency either in the mills or in 

 the mill towns that sprang up about them. Everyone knew 

 that after a time, a few years or many, the timber would be 

 exhausted and the mills abandoned or moved to new localities. 

 It was not a tradition that made either for good social environ- 

 ment or for any care in the treatment of the forest region left 

 behind. 



But in later years, within the past decade for the most part, 

 a new note has crept in. Here and there mills are being built 

 with the basic idea of obtaining timber from one locality for 

 all time. This means, of course, that enough timber will be 

 controlled by that mill so that each year's growth of wood will 

 equal each year's cut. Reduced to its simplest terms, the 

 problem might be stated thus: 



A mill has one hundred square miles of timber under its 

 control. It takes one hundred years for the timber to reach a 

 size profitable to cut. If, then, the mill is of such size and capac- 

 ity that it cuts the merchantable timber on a square mile each 

 year, it will take a century for the entire tract of one hundred 

 square miles to be cut over. By that time the timber on the first 

 square mile that was cut one hundred years ago will be again 

 ready for the saws. A mill so situated need never move for lack 

 of timber since such a forest will produce a yearly harvest for 

 all time. If you think of the forest as the lumber capital, the 



