MERCHANTABLE HEIGHTS WITH TOP DIAMETERS 



187 



This tree, if measured to 6 inches, has the additional length of 1| logs, whose 

 volume is 



The recording of this tree as a four-log tree was probably based on the fact 

 that it would actually be cut at 9 inches in the top instead of at 6 inches. But 

 the cruiser, if he uses this volume table, does not obtain from it the volume of a 

 tree with a 9-inch top, but of one with a 6-inch top. The initial error for this tree 

 consists in not tallying it as a S^-log tree with a 6-inch top. If the full contents 

 of the four actual logs which it contains could be obtained from the table, the 

 error would be the loss of 40 feet in the I5 logs not measured. This is 8 per cent 

 of the total tree volume. But instead, a much greater additional error is incurred. 

 The volume given in the table is for a four-log tree with a 6-inch top containing 

 355 board feet instead of one measuring 9 inches at top. This error, due to differ- 

 ence in top diameter not only of the last log but of the remaining logs, is 95 board 

 feet (450-355) or 21 per cent. 



If the purpose of the estimate is to obtain, not the volume of all trees to 6 inches, 

 but the volume actually to be cut, the attempt to obtain this by dropping the 

 merchantable length of this tree to the 9-inch point, 1^ logs below the 6-inch point, 

 has made the use of the above volume table impossible, for in place of a correct 

 deduction of 8 per cent from the true volume of a 52-log tree, which would give 

 the true volume merchantable, the use of the table has lowered the estimate by 

 27 per cent, which is fff of the desired estimate or 21 per cent too low. Errors 

 of this magnitude and even greater may and have been made in use of volume tables, 

 solely from this source. 



The coordination evidently demands: 



The estimation of height to the same point which has been used 



in constructing such a table. 

 The deduction of the requisite per cent, representing the small 

 top log or logs, to obtain net merchantable volume, in case 

 utilization falls short of this point. 

 Errors in estimating merchantable heights, if consistently too great 

 or too small, incur both the above errors when the tally is applied to 

 the volume table. Other methods of avoiding these errors are: 

 To use total height as a basis. 

 To measure a few heights carefully instead of guessing at many 



or all heights. 

 To construct the table so as to coincide with used top diameters, 

 and then exercise care in employing this same standard in 

 estimating.^ 



' The writer's initial experience in timber cruising was with W. R. Dedon, in 

 Minnesota. Mr. Dedon did not believe in the use of volume tables, claiming that 



