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XLII. On the Measiireme7it of Timber. By Mr. W. Wise- 

 man. 



To the Editors oj" the Philosophical Magazine andjournal. 



"POINDING lately, in your Philosophical Magazine and 

 ■*■ Journal for December last*, a letter by Mr. William Gut- 

 teridge, in which he reprobates, urges a change in, and pro- 

 poses a substitute for, the customary method of timber-mea- 

 suring; I cannot refrain from offering a few observations on 

 the occasion. 



Experience teaches that suggested plausible alterations are, 

 when adopted, not always improvements. 



Mr. Gutteridge evidently proceeds on the supposition that 

 the timber of these kingdoms, when measured for sale, is al- 

 ways in the round state (for, in his new scheme, the only trans- 

 verse dimension he dii'ects to be taken is the diameter at the 

 midlength, and the only content is the cylindric); whereas the 

 fact is, that the far greater part is (what may be called) semi- 

 squared ; that is, the transverse section is brought nearly to 

 the figure of an octagon ; consequently Mr. G.'s plan cannot, 

 with any propriety, be applied to any timber of this descrip- 

 tion. And here, I am of opinion that a better or fairer me- 

 thod for semi-squared timber cannot be devised than the old 

 quarter-girt; for, the nearer the timber is to a perfect square 

 the nearer truth will be the content; and the further from a 

 square, though the purchaser gets a larger quantity, he incurs 

 greater expense in reducing it (as in general he must at using) 

 to a square. The same observation extends to all round tim- 

 ber which is to be converted to the square form at using. But 

 timber being, without doubt, sometimes used in the round 

 state, it is necessary to lay clown rules for ascertaining the true 

 content thereof. 



Again, gi-anting argumcnti cmisu, that timber in general is 

 in the round form, Mr. G. evidently proceeds on the supposi- 

 tion that no rules have hitherto been promulgated by which 

 the true content of such round timber can be determined. 

 This is not the fact. To my knowledge, sliding rules accom- 

 panied by precepts have been in circulation and constant use 

 above 25 years, by which (having either the diameter or quar- 

 ter girt at the middle) not only the cylindric, but also (having 

 any two of the three diameters or quarter girts of the middle 

 and ends) the true conical content of round tapering timber is 

 found with the greatest "ease and brevity." So that the 



* Vol. LX. p. 418. 



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