﻿COTTONWOOD IN THE MISSISSIPPI VALLEY. 43 



$13.88, respectively. Unless the owner were assured that the larger 

 proportion of high grades cut from stands of these greater ages and 

 consequently larger average dimensions would give the standing 

 timber this large increase in value, he would not be justified in 

 deferring the final cut. 



A determination of the rotation necessarily involves some knowl- 

 edge of the manner in which an increase in the size of logs affects 

 the proportion of different grades that can be cut from a given stand. 

 One or two concrete examples will probably make this clear. For 

 instance, one millman kept a detailed record of the grades sawed from 

 certain logs representing the yield of a heavily stocked stand in north- 

 western Mississippi cut clear in 1912. This stand was approximately 

 46 years old, and the logs for the most part ranged from 14 to 30 

 inches top diameter inside the bark. The following proportion of 

 different grades, based on a two months' cut of nearly half a million 

 feet, is believed to be fairly typical of normally stocked pure stands : 



Per cent. 



Boxboards 9 



Firsts and seconds IS 



No. 1 common 30 



No. 2 common 42 



No. 3 common : 1 



In contrast to this is the actual mill tally for a mn of unusually 

 large logs from a stand supposed to be at least 90 years old. These 

 high-grade logs ranged from 24 to 48 inches in diameter at the top 

 and cut out approximately the following grades of lumber : 



Per cent. 



Boxboards 7 



Firsts and seconds 40 



No. 1 common 35 



No. 2 common 15 



No. 3 common 3 



This lumber was graded, moreover, in 1901, when grading rules 

 were more rigid than at present. Under present grading rules a 

 large proportion of this material would be put in the next higher 

 grade. In the judgment of some millmen, timber of this quality 

 would run now more nearly as follows : 



Per cent. 



Boxboards 15 



Firsts and seconds 43 



No. 1 common 30 , 



No. 2 common 10 



No. 3 common 2 



Unfortunately, no records of similar tallies for stands as young 

 as 35 years were found. Several millmen of wide experience, how- 

 ever, gave estimates differing but very little on the probable propor- 

 tion of grades that could be cut from logs ranging from 14 to 24 



