276 TIMBER MEASURING 



OTHER METHODS OP COMPUTING CONTENTS. 



As regards other methods of measuring timber for various 

 purposes, there are besides the quarter girth method just 

 described, the following : 



(1) True Contents Method. 



(2) Calliper Method. 



(3) Die Square Method. 



(4) Board Measure Method. 



True Contents. This is the method almost universally 

 adopted on the Continent when measuring " round " timber. 

 It gives the true mathematical contents. It should be noted 

 that on the Continent the contents of standing crops are 

 nearly always calculated over bark. 



To arrive at the contents, the length in feet is multiplied 

 by the superficial area of the mean section in feet. 



This mean sectional area is found, when timber is felled, 

 by finding the mean diameter, and then : 



(i) by reference to tables ; 

 or (2) by the formula : area = fV 



when r = radius 

 and TT = 3- 14159* 

 which gives the same result as 



^-5, when d = diameter. 

 4 



The diameter is taken in inches, and must be reduced to 

 feet before being multiplied by the length in feet. 



In order to take the diameter, the use of callipers is 

 resorted to ; or sometimes a tree compass. In as much as 

 the section of the majority of trees is not circular, but some- 

 what elliptical, it is advisable to take two diameters at right 

 angles to each other, and then to take the average of the 

 two and calculate as for a circle. By this latter method the 

 error in the true sectional area will only average about I or 

 ij per cent, whereas if one diameter only be taken, the error 

 may amount to as much as 4 per cent. 



By the formula the contents of a log are found thus : 



4 

 (Mean diameter in inches) 2 x length in feet 



~^3~ 

 For x 144 (to reduce to feet) = 183. 



