CRUISING WITH THE AID OF A VOLUME TABLE 53 



Each distinct total for oach species should then be multiplied bj' 5, since the 

 strips tallied covered 20 per cent of the total area. These totals should then be 

 reduced by the percentage estimated in the field for hidden defect and breakage. 

 The total of each species and the grand total of all species for each forty should 

 then be computed by adding together the totals on each tally sheet included in 

 the forty. 



Should any acre tallied be of full size but the tract it represents of irregular 

 size, the area of the fractional tract should be obtained before the estimate is 

 calculated. This can be done with a planimeter by measuring the plat made in 

 the field, or by estimating the number of squares on the plat included in the 

 irregular tract and calculating their equivalent area. The volume of this tract 

 is then secured by multiplying the volume of the acre tallied by the number of 

 acres in the irregular tract. For example, in a 20 per cent cruise each acre 

 talhed represents 5 acres and the total cruise were the area perfectlj^ regular, 

 would be secured by multiplying the volume of the acre tallied by 5. Suppose, 

 however, that one cornev of the tract is logged ofT and from the plat it is found 

 that 2 acres contain no timber. The volume of the acre sheet would then be 

 multiplied by 3 instead of 5. 



If neither the acre tallied nor the tract it represents were complete the 

 volume of the equivalent full acre should be found by dividing the volume of the 

 fractional acre by its area expressed in tenths of an acre. The volume of the 

 fractional tract would then be found as explained above. For example, the last 

 tally sheet coveis but 0.8 of an acre and it represents but 3 acres instead of 5 as 

 normally. The volume of the fractional acre would then be divided by 0.8 to 

 reduce the fractional acre to terms of a whole acre. This volume would then be 

 multii^lied by 3 to find the volume of the tract. The same method might also 

 be applied to the forty as a unit instead of the acre. 



Each party, upon the completion of the work, should hand in all tally sheets 

 and a summary sheet showing the total stand by species for each forty and the 

 grand total for the whole area. 



D. References.— lumbers 37, 55, 57, 59, 61 and 63. 



E. Discussion. 



1. How would the method of procedure outlined above be modified if 



the volume tables to be used were based upon merchantable lengths 

 instead of total heights? 



2. How would the method of procedure be modified if the heights of the 



individual trees were not tallied but the trees on each forty were 

 given one of three height classifications and the volume tables used 

 were constructed with similar height classifications. 



3. Discuss the respective merits of deducting for defect by a percentage 



for each individual tree or by a lump percentage to cover all defects 

 for each acre cruised. 



4. What is the advantage in changing tally sheets at the end of each acre 



rather than at the end of each forty? 



