88 Forestry Quarterly 



lumber than called for by the rule, the scale given by the rule 

 ma}^ be correctly bonused by using a scaling stick on which the 

 o point of the measure is somewhat less than i inch from the 

 i-inch point on the stick. The amount of adjustment necessary 

 to meet any given set of local conditions can only be determined 

 by a careful investigation by a competent person of the sawing 

 qualities of logs cut in the locality. It is fortunate that 

 increased roughness in logs is all but invariably accompanied by 

 increased taper and that while the former tends to decrease the 

 lumber product from logs, the latter has the opposite effect. In 

 most cases the one will be found to offset the other more or less 

 completely, and herein lies an advantage of a top-end measuring 

 rule computed for a conservative taper allowance as compared 

 with a caliper rule which being applied at the middle of the log 

 credits the full amount of taper. 



Mill Tests ivith the Intcryiational Rule. In making mill tests 

 with the International Rule it must never be overlooked that the 

 standard scaling score (published herewith) is computed for a 

 kerf allowance of ^-inch and a factor of safety in the thickness 

 of the boards of y\-inch ( for uneven sawing and shrinkage) or a 

 total allowance of y\-inch. The first step in making a test is to 

 determine accurately the corresponding margin for kerf and 

 shrinkage being made by the mill in which the logs are to be 

 sawn. This can be most conveniently and accurately done by 

 observing the loss in width of square timbers (/. e. logs after 

 slabbing all four sides) from cutting any particular number of 

 inch boards from their sides. The larger the number of boards 

 sawn in this test the better will be the average figure for the 

 total allowance. For example, let it be assumed that the cut- 

 ting of 40 "inch" boards cost the square timbers under meas- 

 urement a total of 52.5 inches, thus giving an average of y\-inch 

 total allowance, which corresponds with a ^-inch kerf -\- y^g^-inch 

 for shrinkage. The 40 boards cut under the standard condi- 

 tions (/. e. ^-inch kerf -f yVinch shrinkage) would cost the 

 timbers but 47.5 inches. Therefore the total scale given by the 

 rule for the logs tested must be reduced for that particular mill 

 in the proportion of 52.5 to 47.5, or in other words 9.5 per cent. 

 The next step in the test is to measure the logs sawn together 

 with their product in square-edged lumber after manufacture. 

 In my work I have measured the log diameters, top and butt, 

 twice at right angles correct to tenths of inches, the mean being 



