MEASUREMENT OF TIMBER 199 



Where a single tree is measured two diameters at right angles 

 should be taken, and the average between the two is the 

 diameter of the tree. This is necessary, as trees may be, and 

 often are, larger in diameter in one direction than they are 

 in another. Where large numbers of trees are measured the 

 average is obtained by measuring each tree in a different 

 direction, the first being taken say north and south, the next 

 east and west, and so on. By doing this, about half the trees 

 will be taken on the long diameter and the other half on the 

 short diameter, and no great inaccuracy will be obtained in 

 the total volume of the wood. 



When measuring whole woods it is not necessary to take 

 the diameter accurately to the tenth part of an inch. All trees 

 between 7^ and 8| inches diameter are taken as 8 inches ; all 

 between 8J and 9^ as 9 inches, and so on ; this reduces the 

 work, and it is found in practice that doing this makes no 

 perceptible difference to the volume of the wood, as there will 

 be about as many trees from 8J to 9 inches as there are from 

 9 to 9f , and the average diameter of all the trees from 8| to 9^ 

 will in fact be practically 9 inches. There are several slightly 

 different ways of measuring a wood when using callipers, but 

 the most convenient for the woodman for all ordinary purposes 

 is as follows. 



A party of three or more men work up and down the wood, 

 taking narrow strips at a time. One man books the measure- 

 ment, the others take the diameters of all the trees, with 

 callipers, calling out the result to the booker. The calliper 

 men should place a chalk mark on each tree as it is measured 

 to prevent its being taken again, all chalk marks being made 

 on the side of the tree which will be visible when they return 

 on the next strip. The booker enters the trees in his note- 

 book, as they are called out, as follows : 



