56 NOTES ON FORESTRY. 



slabs are of little value, but in logs of 8 to 12 ft. 

 girth, such as are commonly sold by this Depart- 

 ment, the loss to the seller is considerable. But 

 it must be borne in mind that, as logs approach 

 the four-sided form, the girth increases its propor- 

 tion to the diameter, and the square of the quarter 

 girth gives truer results than the method for 

 determining the contents of cylindrical bodies, 

 which method, if pursued with squared timber, 

 would result in a loss to the seller of 22 per cent. 

 But as the Department generally sells round logs, 

 I would recommend that, when the diameter is 

 over 18 inches, the contents should be determined 

 by multiplying the square of the mean diameter by 

 7854 and by the length. If the mean circumfer- 

 ence is taken, then the square of this multiplied by 

 07958. 



There is yet another source of error and of 

 consequent loss to the seller in this mode, the 

 area of the middle of a tapering log being always 

 less than the mean area. In ordinary timber 

 sales the loss is trifling, as the logs sold rarely vary 

 more than 6 inches in their extreme diameters, 

 on which difference the loss is only 3 inches 

 on the average area, or of one cubic foot in 48 

 feet of length. With 12 inches of difference 

 in the extreme diameters, the loss is 12 inches on 

 average area, or a cubic foot in 12 feet of length; 



