Forest Mensuration 203 



acres evenly, but it is just as well for each man to make 

 up one to suit himself. 



If the area of the tract is not definitely known, and it 

 is not desirable to go to the trouble of a survey, a fairly 

 accurate percentage may be secured by the proper spacing 

 of the four-rod strips. If the strips are four rods apart, 

 they will contain 50 per cent, twelve rods apart 25 per cent, 

 sixteen rods apart 20 per cent, 36 rods apart 10 per cent, 

 76 rods apart 5 per cent and 156 rods apart 2| per cent. 

 The larger the percentage taken, the more accurate the 

 estimate will be, and less than 25 per cent should never 

 be taken on any woodlot. 



When this data has been obtained, the field work is 

 completed and the remainder of the work must be done 

 in the office. This work consists of converting the logs 

 into board measure by means of a log scale. The most 

 widely used log scales are printed in the appendix. The 

 process is as follows : first, look up the log scale used in 

 that district in which the logs are to be sold. Turning to 

 the column of the log scale representing the logs of the 

 length in the first column of the tally sheet, look up the 

 first diameter appearing on the tally sheet and write down 

 opposite to it the number of board feet given in the scale 

 for that diameter. This represents the number of board 

 feet that may be cut from a log of this length and diameter. 

 Multiply this by the number of logs of this class and write 

 it down in the next column to the right. This must be 

 done for every diameter of the different lengths appearing 

 on the tally sheet. The sum of each column will represent 

 the total number of board feet in the logs of certain length 

 and species. The sum of the totals of all the columns will 



