SPAULDING LOG RULE, 1868 75 



instance a similar but worse confusion might have resulted, but was avoided by the 

 adoption of a single standard of values prepared by the U. S. Forest Service about 

 1905, and published in the Woodsman's Handbook, 1910 edition. The extension 

 (made by E. A. Ziegler) was based on a comparison of the curve formed by the 

 plotted values of the rule with similar curves for the formula rules such as the 

 International, and for the Spaulding rule. Ziegler states, "It might be described 

 as an extension built on an old rule by graphic methods checked with the correct 

 mathematical formula in which the slab waste varies with D and the kerf with D^, 

 and compared with the accepted rules in the Northwest, notably the Spaulding." 

 The extension was built up on a 12-foot log, and applied to lengths of from 8 to 

 16 feet. As a concession to logging methods in the Northwest, logs up to 32 feet 

 were scaled without taper by this rule. 



No such difficulties in extension are encountered with rules constructed by the 

 use of correct formulae, since the values of logs of all sizes are in this way determined. 



Attempt to Improve the Rule. Further efforts to modify this log rule have been 

 made in order to even off the irregularities of value between contiguous sizes. 

 Examples of this are the Hanna log rule, 1885 (John S. Hanna, Lock Haven, Pa.), 

 the White rule, 1898 (J. A. White, Augusta, Mont.) and a local rule used by M. E. 

 Ballou & Son, Becket, Mass., 1888, adopted from Scribner rule, for small logs. Such 

 modifications unquestionably improve the rule, but the minor irregularities do not 

 appreciably modify the scale of a large number of logs of different sizes. The con- 

 fusion which would result in attempting to secure universal agreement on any change 

 in accepted values for this rule has prevented their adoption, and the values still 

 stand as they were originally determined, subject only to the conversion to decimal 

 form. 



The Scribner Decimal " C " log rule in spite of its imperfections 

 comes the nearest at present to fulfilling the demand for a universal 

 commercial log rule, because of its present wide acceptance and use 

 (§ 13), and reasonable consistency in over-run. The latter reason alone 

 makes it preferable to the Doyle rule. " Not even this rule, however, 

 does justice to logs below 12 inches in diameter; and in regions of second 

 growth and small logs, a closer and more accurate rule is preferable. 



69. Spaulding Log Rule, 1868. Synonym: California Rule. The 

 Spaulding Log Rule was adopted by statute in 1878 as the standard for 

 California, and the values were given. It was constructed by N. W. 

 Spaulding of San Francisco in 1868 from diagrams of logs from 10 to 96 

 inches in diameter, using an ^-inch saw kerf, and 1-inch lumber, and 

 afterwards tested by sawing logs of each size in two mills. The size of 

 the slab (width of minimum board) was varied according to the size of 

 the log. This error of construction tends to increase the over-run in 

 large logs. The values were given for lengths from 12 to 24 feet. The 

 author directed that longer logs be scaled by doubling the values in the 

 table, and this practice was incorporated in the statute. Thus the 

 rule neglects taper altogether. In scaling, this principle is not applied 

 to logs longer than 40 feet. It constitutes the most serious defect of the 

 rule at present. Owing to the large saw kerf considerable over-run is 



