184 



VOLUME TABLES FOR BOARD FEET 



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coincide with the portion of the tree which is actually used, and the 

 average top diameter with that which is actually cut. 



But the variable practice of sawing and the arbitrary standards 

 set by saw crews as to waste in the tops, differing with different crews, 

 logging jobs, regions and seasons, is a strong 

 argument for adopting a fixed standard for 

 top diameters for saw timber. This stand- 

 ard may either conform to the average 

 diameter utilized, or may depart from it 

 and be smaller; e.g., as at B7. 



Where a fixed top diameter is chosen, 

 instead of the variable one coinciding with 

 utilization practice, the last taper measure- 

 ment will usually fall above or below this 

 diameter, as before. Here the same rule 

 of give and take can be applied; but if the 

 diameter limit is small the top tapers rap- 

 idly and it may be preferable to take no 

 measurement of less than the minimum top 

 diameter. The last top measurements will 

 then fall always either at or below the 

 point. 



Where 16-foot measurements only are 

 made, it is necessary to take an 8-foot 

 length at the top whenever the last cut 

 falls more than 4 feet distant from the last 

 16-foot taper. This is another reason for 

 taking 8-foot tapers throughout. 



156. Defective Trees, Measurement. 

 Frequently one or two top logs in certain 

 trees will not be utilized because of defects 

 in the upper portion of the bole. Where 

 the table is based on actual utilization, 

 such trees should be rejected for measure- 

 ment or else the defective logs should be 

 measured, since the cull is not due to form 

 but to defect. Where the top diameter is 

 fixed independent of the last cut, these defective trees should be 

 measured. All trees are suitable for volume measurements except 

 forked-topped trees, those with abnormal D.B.H. dimensions due 

 to butt swelling and frequently caused by fire scars, and trees 

 deformed in such a manner that a series of normal taper measure- 

 ments cannot be obtained. Abnormalities at a given taper point 



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