On the Mcasiinnnciit of Timber. 421 



But it may be observed, tliat the greater the disparity of 

 the bases, the greater the loss to the grower ; there being a 

 constant fluctuation ; and which, however higli, as before ob- 

 served, is never so lo'do as 20 per centum. 



I will therefore show two original methods of ascertaining 

 the ci/Jindrical content of any log. 



First original Method. 

 1st. Measure the length as usual. 



2d. Measure the diameter at the half length with a pair of 

 sliding-ride callipers, which I have constructed for this sole 

 purpose. And 



3dly. (Upon this new instrument) Set the diameter on C 

 to the same on D ; and against the length on A stands the 

 content on B. 



The operation for the figure Avill be, 

 on C. on D. on A. on B. 

 As 2 : 2 : : 40 : 125-66 = feet in a cylinder, 

 diam. diani. length, content. 



And if from 1 25*66 feet, the cylindrical content, 

 we take 98*70 feet, the eiistomarj/ content. 



there are left 26*96 feet, gained to the grower by the method 



here ])r<)posed. 



And if tio)n 136*136 fiict, the real content, 



be taken 1 25*660 feet, the cylindrical content. 



there are left 10*476 feet in favour of the purchaser, as a 

 compensation for irregularities of growth. But where timber 

 is regularly grown, and there is so great a dis})arity between 

 the extreme diameters as 3 to 1, according to the figure, and 

 the timber be of the more valuable species, the same allowance 

 does not seem just ; and in such case the log should be mea- 

 sured in \wo frusta of c(iual length, thus : 



Take the diameter of the larger frustum at h, of the figure, 

 or a quarter the length of the entire log, for the one-half length; 

 and at d, or three-quarters the length, take the diameter for 

 the other half length, which, to follow the precept before laid 

 down, will give as follows ; viz. 



on C. on I), on A. on B. 

 As 2-5 : 2*5 :: 20 : 98*175 fecf. 

 diam. diam. half content of 

 length, larger trust, 

 on ('. on D. on A. on H. 

 and as 1 *5 : I *5 : : 20 : 35*343 feet, 

 diaui. dinui. half content of 



length, smaller trust. 



Here 



